WO2007053852A2

WO2007053852A2 - Cementitious composites having wood-like properties and methods of manufacture

Info

Publication number: WO2007053852A2
Application number: PCT/US2006/060455
Authority: WO
Inventors: Simon K. Hodson; Per Just Andersen
Original assignee: E. Khashoggi Industries, Llc
Priority date: 2005-11-01
Filing date: 2006-11-01
Publication date: 2007-05-10
Also published as: CN101346321A; EP1954645A2; CA2627717A1; WO2007053852A3; AU2006308536A2; AU2006308536A1; EP1954645A4; MX2008005688A; BRPI0618052A2

Abstract

A method of manufacturing a cementitious composite includes: (1) forming mixing an extrudable cementitious composition by first forming a fibrous mixture comprising fibers, water and a rheology modifying agent and then adding hydraulic cement; (2) extruding the extrudable cementitious composition into a green extrudate, wherein the green extrudate is characterized by being form-stable and retaining substantially a predefined cross-sectional shape; (3) removing a portion of the water by evaporation to reduce density and increase porosity; and (4) causing or allowing the hydraulic cement to hydrate to form the cementitious composite. Such a process yields a cementitious composite that is suitable for use as a wood substitute. The wood-like building products can be sawed, nailed and screwed like ordinary wood.

Description

CEMENTITIOUS COMPOSITES HAVING WOOD-LIKE PROPERTIES AND METHODS OF MANUFACTURE

BACKGROUND OF THE INVENTION I. The Field of the Invention The present invention relates generally to cementitious building products that contain reinforcing fibers, more particularly, to extrudable cementitious compositions for use in manufacturing cementitious building products having wood-like properties. H. The Related Technology

Lumber and other building products obtained from trees have been a staple for building structures throughout history. Wood is a source for many different building materials because of its ability to be cut and shaped into various shapes and sizes, its overall performance as a building material, and its ability to be formed into many different building structures. Not only can trees be cut into two-by-fours, one-by-tens, plywood, trim board, and the like, but different pieces of lumber can be easily attached together via glue, nails, screws, bolts, and other fastening means. Wood lumber can be easily shaped and combined with other products to produce a desired structure.

While trees are a renewable resource, it can take many years for a tree to grow to a usable size. As such, trees may be disappearing faster than they can be grown, at least locally in various parts of the world. Additionally, deserts or other areas without an abundance of trees either have to import lumber or forgo constructing structures that require wood. Due to concerns regarding deforestation and other environmental issues relating to the cutting of trees, there has been an attempt to create "lumber substitutes" from other materials such as plastics and concretes. While plastics have some favorable properties such as moldability and high tensile strength, they are weak in compressive strength, are generally derived from non-renewable resources, and are generally considered to be less environmentally unfriendly than natural products.

On the other hand, concrete is a building material that is essentially un-depletable because its constituents are as common as clay, sand, rocks, and water. Concrete usually includes hydraulic cement, water, and at least one aggregate, wherein the water reacts with the cement to form cement paste, which binds the aggregates together. When the hydraulic cement and water cure (i.e., hydrate) so as to bind it, aggregates and other solid constituents together, the resulting concrete can have an extremely high compressive strength and flexural modulus, but is a brittle material with relatively low tensile strength compared to its compressive strength, with little toughness or deflection properties. Nevertheless, by adding strengtheners such as rebar or building massive structures, concrete is useful for constructing driveways, building foundations, and generally large, massive structures.

Previous attempts to create lumber substitutes with concrete have not provided products with adequate characteristics. In part, this is because of the traditional approaches to fabricating concretes that require mixtures to be cured in molds, and have not provided products with the proper toughness or fiexural strength to be substituted for lumber. One attempt to manufacture wood substitutes from concrete involves the "Hatschek process", which is a modification of the process used to manufacture paper.

In the Hatschek process, building products are made from a highly aqueous slurry containing up to 99% water, hydraulic cement, aggregates and fibers. The aqueous slurry has an extremely high water-to-cement ("w/c") ratio and is dewatered to yield a composition that is capable of curing to form solid building products. The aqueous slurry is applied in successive layers to a porous drum and dewatered between subsequent layers. The fibers are added to keep the solid cement particles from draining off with the water and impart a level of strength. When still in a moist, unhardened condition, the dewatered material is removed from the drum, optionally shaped, and allowed to cure. The resulting products are layered. While adequately strong when kept dry, they tend to separate or delaminate when exposed to excessive moisture over time. Because the products are layered, the components, particularly the fibers, are not homogeneously dispersed. Other building products manufactured using hydraulically settable binders include gypsum wallboard and cement board. Gypsum wallboard is used extensively in the building industry as a structural material for walls. Because it is very sensitive to moisture, it is general unsuitable for use in showers and other areas having high moisture. Cement board is more resistant to the effects of water and can be used as a substitute for gypsum board. Wallboard is typically made by placing an aqueous slurry between sheets of paper. Both gypsum board and cement board are highly brittle, which allows them to be scored and broken to yield boards of a desired size. While it is possible to inserts nails and screws in such wallboards, they have low nail and screw hold. That is because they easily fracture under the point load of nails and screws because they lack toughness. Thus, while wallboard can be nailed or screwed into underlying wood or metal boards, wallboard is not a good structural material on its own. Indeed, when attaching appliance or other fixtures to wallboard, it is generally necessary to use a molly anchor or toggle bolt, since a nail or screw by itself will easily pull out of wallboard.

While the current inventors previously invented methods for manufacturing flexible paper-like sheets using cement and fibers, such sheets were flexible like paper and could be bent, folded or rolled into a variety of different food or beverage containers much like paper. Such sheets would not be suitable for use as a building material. For one thing, such sheets were made by quickly drying a moldable composition on a heated Yankee roller within seconds or minutes of formation, which resulted in the hydraulic cement particles becoming mere fillers, with the rheology-modifying agent providing most, if not all, of the binding force. Because the cement particles were acting merely as fillers, they were eventually replaced with cheaper calcium carbonate filler particles.

It would therefore be advantageous to provide a cementitious composition and method for preparing wood-like building products that can be used as a substitute for lumber products and that could be manufactured without having to dewater a highly aqueous slurry. Moreover, it would be beneficial to provide cementitious building products that could be used as a substitute for wood, including a wide variety of wood building products, such as structural and decorative products currently made from wood.

SUMMARY OF THE INVENTION The present invention relates to cementitious building materials that can function as a substitute for lumber. Accordingly, the present invention involves the use of extrudable cementitious compositions that can be extruded or otherwise shaped into wood-like building product that can be used as a substitute for many known lumber products. The fibrous cementitious building products can have properties similar to wood building products. In some embodiments, the fibrous cementitious building products can be sawed, cut, drilled, hammered, and affixed together as is commonly done with wood building products and described in more detail below.

Ordinary concrete is generally much denser and harder than wood and therefore much harder to saw, nail or screw into. In general, the ability of cementitious building to be sawed using ordinary wood saws, nailed using a hammer, or screwed using a common driver is a function of hardness, which is approximately proportional to the density (i.e., the lower to density, the lower the hardness as a general rule). In cases where it will be desirable for the cementitious building products to be sawed, nailed and/or screwed using tools commonly found in the building industry when using wood products, the cementitious building products will generally have a hardness that approximates that of wood (i.e., so as to be softer than conventional concrete). The inclusion of fibers and rheology modifying agent assist in creating products that are softer than conventional concrete. In addition, the inclusion of a substantial quantity of well-dispersed pores helps reduce density which, in turn, helps reduce hardness. Though not strictly a measurement of hardness, the flexural modulus of a material has been found to correlate with hardness as it relates to the ability to saw, nail and/or screw cementitious building products. Ordinary concrete typically has a flexural modulus with an order of magnitude measured in hundreds of gigapascals (10^π Pa), which translates into an order of magnitude of about 10⁷psi. In contrast, the flexural modulus of wood ranges from about 500,000 psi up to about 5,000,000 (about 3.5 to 35 gigapascals). Concrete is typically about 5 to 100 times harder than wood. Softer woods, like pine, which are more easily sawed, nailed and screwed than harder woods, are up to 100 times softer than concrete, as approximated by flexural modulus. In one embodiment, the present invention includes a cementitious composite product for use as a lumber substitute. Such a product can include a cured cementitious composite comprised of hydraulic cement, a rheology-modifying agent, and fibers. The cured cementitious composite can be characterized by the following: being capable of being sawed by hand with a wood saw; a flexural modulus in a range of about 200,000 psi to about 5,000,000 psi; a flexural strength of up to about 4,000 psi; a preferred density less than about 1.2 g/cm³, more preferably less than about 1.15 g/cm³, even more preferably less than about 1.1 g/cm³, and most preferably less than about 1.05 g/cm³, and fibers substantially homogeneously distributed through the cured cementitious composition, preferably at a concentration greater than about 10% by dry weight. The building products manufactured according to the present invention are much stiffer than cement-containing paper-like products. Because the fibers are substantially homogeneously dispersed (i.e., are not layered as in the Hatschek process), the building products do not separate or delaminate when exposed to moisture.

The cured cementitious composition is prepared by mixing an extrudable cementitious composition including water at a concentration from about 25% to about 75% by wet weight, hydraulic cement at a concentration from about 25% to about 75% by wet weight, a rheology-modifying agent at a concentration from about 0.25% to about 5% by wet weight, and fibers at a concentration greater than about 5% by wet weight. The extruded compositions are characterized as having a clay-like consistency with high yield stress, Binghamian plastic properties and immediate form stability. After being mixed, the extrudable cementitious composition can be extruded into a green extrudate having a predefined cross-sectional area. The green extrudate is advantageously form-stable upon extrusion so as to be capable of retaining its cross-sectional area and shape so as to not slump after extrusion and so as to permit handling without breakage. After being extruded, the hydraulic cement within the green extrudate can be cured so as to form the cured cementitious composite.

According to one embodiment, the amount of water that is initially used to form an extrudable composition is reduced by evaporation prior to, during or after hydration of the cement binder. This may be accomplished by drying in an oven, typically at a temperature below the boiling point of water to yield controlled drying while not interfering with cement hydration. There are at least two benefits that result from such drying: (1) the water to cement ratio can be reduced, which increases the strength of the cement past and (2) the removed water leaves behind porosity, which can substantially reduce the density and hardness of the resulting product without a concomitant reduction in strength.

The nominal or apparent water/cement ratio of the extrudable composition can initially be in a range of about 0.8 to about 1.2. However, the effective water/cement ratio based on water that is actually available for cement hydration is typically much lower. For example, after removing a portion of the water by evaporation, the resulting water/cement ratio is typically in a range of about 0.1 to about 0.5, e.g., preferably about 0.2 to about 0.4. more preferably about 0.25 to about 0.35, and most preferably about 0.3. It has been found that not all of the added water can be removed by evaporation by heating in an oven at a temperature of 145°F (63°C), which indicates that some of the water is able to react with and hydrate the cement even while heating, making it chemically bound water rather than free water that can be evaporated off. This process differs from processes that utilize steam curing, in which no water is removed, or that heat a material above the boiling point of water, wherein water is removed too rapidly to permit significant hydration of the cement particles.

The fibers used in the cementitious composites according to the invention can be one or more of hemp fibers, cotton fibers, plant leaf or stem fibers, hardwood fibers, softwood fibers, glass fibers, graphite fibers, silica fibers, ceramic fibers, metal fibers, polymer fibers, polypropylene fibers, and carbon fibers. The amount of fibers that are substantially homogeneously distributed through the cured cementitious composition is preferably greater than about 15% by dry weight, more preferably greater than about 20% by dry weight. Some fibers, such as wood or plant fibers, have a high affinity for water and are able to absorb substantially quantities of water. That means that some of the water added to a cementitious composition to make it extrudable may be tied up with the fibers, thereby reducing the effective water/cement ratio as water tied up by the fibers is not readily available to hydrate the cement binder. The hydraulic cement binder used in the cementitious composites according to the invention can be one or more of Portland cements, MDF cements, DSP cements, Densit-type cements, Pyrament-type cements, calcium aluminate cements, plasters, silicate cements, gypsum cements, phosphate cements, high alumina cements, micro fine cements, slag cements, magnesium oxychloride cements, and combinations thereof. The cement binder contributes at least about 50% of the overall binding strength of the building product (e.g., in combination with binding strength imparted by the rheology modifying agent). Preferably, hydraulic cement will contribute at least about 70% of the overall binding strength, more preferably at least about 80%, and most preferably at least about 90% of the binding strength. Because the hydraulic cement binder contributes substantially to the overall strength of the building materials, they are much stronger and have much higher flexural stiffness compared to paper-like products that employ hydraulic cement mainly as a filler (i.e., by virtue of heating to 150⁰C and above to rapidly remove all or substantially all of the water by evaporation). The rheology modifying agent can be one or more of polysaccharides, proteins, celluloses, starches such as amylpectin, amulose, seagel, starch acetates, starch hydroxyethers, ionic starches, long chain alkyl-starches, dextrins, amine starches, phosphate starches, dialdehyde starches, cellulosic eithers such as methylhydroxyethylcellulose, hydroxymethylethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and clay. The rheology modifying agent is preferably included in an amount in a range of about 0.25% to about 5% by wet weight of the cementitious composition, more preferably in a range of about 0.5% to about 4% by wet weight, and most preferably in a range of about 1% to about 3% by wet weight. Like the fibers, the rheology modifying agent can bind with water, thereby reducing the effective water/cement ratio compared to the nominal ratio based on actual water added rather than water that is available for hydration. While the rheology modifying agent can act as a binder, it will typically contribute less than about 50% of the overall binding force.

Optionally, a set accelerator at a concentration from about 0.01% to about 15% by dry weight can be included, wherein the set accelerator can be one or more of Na₂OH, KCO3, KOH, NaOH, CaCl2, CO2, magnesium chloride, triethanolamine, aluminates, inorganic salts of HCl, inorganic salts of HNO₃, inorganic salts of H2SO4, calcium silicate hydrates (C-S-H), and combinations thereof. Set accelerators may be especially useful in the case where rapid strength is desired for handling and/or where a portion of the water is removed by evaporation during initial hydration. An aggregate material can also be included, which is one or more of sand, dolomite, gravel, rock, basalt, granite, limestone, sandstone, glass beads, aerogels, perlite, vermiculite, exfoliated rock, xerogels, mica, clay, synthetic clay, alumina, silica, fly ash, silica fume, tabular alumina, kaolin, glass microspheres, ceramic spheres, gypsum dihydrate, calcium carbonate, calcium aluminate, and combinations thereof.

Tn one embodiment, the cured cementitϊous composite can receive a 1Od nail by being hammered therein with a hand hammer. The cured cementitious composite can have a pullout resistance of at least about 25 lbf/in for the 1Od nail, preferably at least about 50 lbf/in for the 1Od nail. Additionally, the cured cementitious composite can have a pullout resistance of at least about 300 lbf/in for a screw, preferably at least about 500 lbf/in for the screw. Pullout resistance is generally related to the amount of fibers within the cementitious composite (i.e., increases with increasing fiber content, all things being equal). The fibers create greater localized fracture energy and toughness that resists formation or cracks in and around a hole made by a nail or screw. The result is a spring back effect in which the matrix holds the nail by frictional forces or the screw by both frictional and mechanical forces.

In one embodiment, the method of making the cementitious composite can include extruding the extrudable cementitious composition around at least one reinforcing member selected from the group consisting of rebar, wire, mesh, and fabric so as to at least partially encapsulate the reinforcing member within the green extrudate. In one embodiment, the method of making the cementitious composite product can include the following: extruding a green extrudate having at least one continuous hole that is form-stable; inserting a rebar and a bonding agent into the continuous hole while the cementitious composite is in a form-stable green state or is at least partially cured; and bonding the rebar to a surface of the continuous hole with the bonding agent. Optionally, the bonding agent is applied to the rebar before inserting the rebar.

In one embodiment, method of making the cementitious composite product can include configuring the cementitious composite into a building product so as to be a substitute for a lumber building product. As such, the building product can be fabricated into a shape selected from the group consisting of a rod, bar, pipe, cylinder, board, I-beams, utility pole, trim board, two-by-four, one-by-eight, panel, flat sheet, roofing tile, and a board having a hollow interior. The building products are typically manufactured using a process that includes extrusion, but which may also include one or more intermediate or finishing procedures. An intermediate procedure typically occurs while the composition is in a green, uncured state, while a finishing procedure typically occurs after the material has been cured or hardened. -S-

Unlike wood, which cannot be appreciably softened except by damaging or weakening the wood structure, concrete is plastic and moldable prior to curing. Building products made therefrom can be reshaped (i.e., curved or bent) while in a green state to yield shapes that are generally hard or impossible to attain using real wood. The surface or cementitious matrix of the building products can be treated so as to be waterproof using waterproofing agents such as silanes, siloxanes, latexes, and other waterproofing agents known in the concrete industry, which is a further advantage over wood. Such materials may be mixed into and/or applied to the surface of the cementitious building products.

The building products may be solid or they may be hollow. Providing continuous holes by extruding around a solid mandrel to yield a discontinuity yields building products that are lightweight. One or more of such holes can be filled with rebar reinforcement (e.g., bonded with epoxy or other adhesive), they may provide a conduit for electrical wires, or they can be used to screw into the building product much like a pre-drilled hole. The building products may comprise complex extruded structures. They may have virtually any size or cross sectional shape. They can be formed into large sheets (e.g., by roller-extruding) or blocks (e.g., through large die openings) and then milled into smaller sizes like wood.

In one embodiment, a method of making the cementitious composite product can include processing the form-stable green extrudate and/or cured cementitious composite by at least one process selected from the group consisting of bending, stamping, impact molding, cutting, sawing, sanding, milling, texturizing, planing, polishing, buffing, pre- drilling holes, painting, and staining.

In one embodiment, a method of making the cementitious composite product can include recycling a portion of a scrap green extrudate or material cut away from the main body of a building product (e.g., by stamping), wherein the recycling includes combining the scrap green extrudate with an extrudable cementitious composition.

In one embodiment, the process for curing the hydraulic cement can include heat curing or autoclaving.

In one embodiment, the extrusion can be through a die opening. Alternatively, the extrusion can be by means of roller-extrusion. These and other embodiments and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

Figure I A is a schematic diagram that illustrates an embodiment of an extruding process for manufacturing a cementitious building product;

Figure IB is a schematic diagram that illustrates an embodiment of an extruding die head for manufacturing a cementitious building product having a continuous hole extending therethrough;

Figure 1C is a perspective view that illustrates embodiments of the cross-sectional areas of extruded cementitious building products;

Figure 2 is a schematic diagram that illustrates an embodiment of a roller-extrusion process for preparing a cementitious building product; Figures 3A-D are perspective views that illustrate embodiments of co-extruding a cementitious building product with a structurally reinforcing element;

Figure 4 is a schematic diagram that illustrates an embodiment of a process for structurally reinforcing a cementitious building product;

Figure 5A is a perspective view that illustrates prior art concrete and a nail inserted therein;

Figure 5B is a perspective view that illustrates an embodiment of a cementitious building product and a nail inserted therein;

Figure 6A is a longitudinal cut-away view of Figure 4;

Figure 6B is a mid-level cross-sectional view of Figure 6 A; Figure 7A is a longitudinal cut-away view of Figure 5;

Figure 7B is a mid-level cross sectional view of Figure 7A.

Figure 8 is a graph of flexural strengths of wood, an embodiment of a cementitious building product, and an embodiment of a rebar-reinforced cementitious building product;

Figure 9 is a graph of a tensile strength of an embodiment of a cementitious building product; and

Figure 10 is a graph of the displacement of wood and an embodiment of a cementitious building product by a compressive force. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Generally, the present invention is related to cementitious compositions and methods for preparing such compositions and manufacturing cementitious building products that have properties similar to wood building products. The terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting. I. General Definitions

The term "multi-component" refers to fiber-reinforced cementitious compositions and extruded composites prepared therefrom, which typically include three or more chemically or physically distinct materials or phases. For example, these extrudable compositions and resulting building products can include components such as rheology- modifying agents, hydraulic cements, other hydraulically settable materials, set accelerators, fibers, inorganic aggregate materials, organic aggregate materials, dispersants, water, and other liquids. Each of these broad categories of materials imparts one or more unique properties to extrudate mixtures prepared therefrom as well as to the final article. Within these broad categories it is possible to further include different components (such as two or more inorganic aggregates or fibers) which can impart different, yet complementary, properties to the extruded article.

The terms "hydraulically settable composition" and "cementitious composition" are meant to refer to a broad category of compositions and materials that contain both a hydraulically settable binder and water as well as other components, regardless of the extent of hydration or curing that has taken place. As such, the cementitious materials include hydraulic pastes or hydraulically settable compositions in a green state (i.e., unhardened, soft, or moldable), and a hardened or set cementitious building product.

The term "homogeneous" is meant to refer to a composition to be evenly mixed so that at least two random samples of the composition have roughly or substantially the same amount, concentration, and distribution of a component.

The terms "hydraulic cement," "hydraulically settable binder," "hydraulic binder," or "cement" are meant to refer to the component or combination of components within a cementitious or hydraulically settable composition that is an inorganic binder such as, for example, Portland cements, fly ash, and gypsums that harden and cure after being exposed to water. These hydraulic cements develop increased mechanical properties such as hardness, compressive strength, tensile strength, flexural strength, and component surface bonds (e.g., binding of aggregate to cement) by chemically reacting with water.

The terms "hydraulic paste" or "cement paste" are meant to refer to a mixture of hydraulic cement and water in the green state as well as hardened paste that results from hydration of the hydraulic binder. As such, within a hydraulically settable composition, the cement paste binds together the individual solid materials, such as fibers, cement particles, aggregates, and the like.

The terms "fiber" and "fibers" include both natural and synthetic fibers. Fibers typically having an aspect ratio of at least about 10:1 are added to an extrudable cementitious composition to increase the elongation, deflection, toughness, and fracture energy, as well as flexural and tensile strengths of the resulting extruded composite or finished building product. Fibers reduce the likelihood that the green extrudate, extruded articles, and hardened or cured articles produced therefrom will rupture or break when forces are applied thereto during handling, processing, and curing. Also, fibers can provide wood-like properties to cementitious building products, such as nail hold, screw hold, pullout resistance, and the ability to be sawed by machine or a handsaw, and/or be drilled with a wood-drilling bit. Fibers can absorb water and reduce the effective water/cement ratio.

The term "fiber-reinforced" is meant to refer to fiber-reinforced cementitious compositions that include fibers so as to provide some structural reinforcement to increase a mechanical property associated with a green extrudate, extruded articles, and hardened or cured composites as well as the building products produced therefrom. Additionally, the key term is "reinforced," which clearly distinguishes the extrudable cementitious compositions, green extrudate, and cured building products of the present invention from conventional settable compositions and cementitious articles. The fibers act primarily as a reinforcing component to specifically add tensile strength, flexibility, and toughness to the building products as well as to reinforce any surfaces cut or formed thereon. Because they are substantially homogeneously dispersed, the building products do not separate or delaminate when exposed to moisture as can products made using the Hatschek process. The term "mechanical property" is meant to include a property, variable, or parameter that is used to identify or characterize the mechanical strength of a substance, composition, or article of manufacture. Accordingly, a mechanical property can include the amount of elongation, deflection, or compression before rupture or breakage, stress and/or strain before rupture, tensile strength, compressive strength, Young's Modulus, stiffness, hardness, deformation, resistance, pullout resistance, and the like.

The terms "extrudate," "extruded shape," or "extruded article," are meant to include any known or future designed shape of articles that are extruded using the extrudable compositions and methods of the present invention. For example, the extruded composite can be prepared into rods, bars, pipes, cylinders, boards, I-beams, utility poles such as power poles, telephone poles, antennae poles, cable poles, and the like, two-by-fours, one-by-fours, panels, flat sheets, other traditional wood products, roofing tiles, boards having electrical conduits, and rebar-reinforced articles. Additionally, an extruded building product can initially be extruded as a "rough shape" and then shaped, milled or otherwise refined into an article of manufacture, which is intended to be included by use of the present terms. For example, a slab or large block (e.g., a 16-by-16) can be cut or milled into a plurality of two- by-fours.

The term "extrusion" can include a process where a material is processed or pressed through an opening or through an area having a certain size so as to shape the material to conform with the opening or area. As such, an extruder pressing a material through a die opening can be one form of extrusion. Alternatively, roller-extrusion, which includes pressing a composition between a set of rollers, can be another form of extrusion. Roller- extrusion is described in more detail below in Figure 2. In any event, extrusion refers to a process that is used to shape a moldable composition without cutting, milling, sawing or the like, and usually includes pressing or passing the material through an opening having a predefined cross-sectional area.

The terms "hydrated" or "cured" are meant to refer to a level of a hydraulic reaction which is sufficient to produce a hardened cementitious building product having obtained a substantial amount of its potential or maximum strength. Nevertheless, cementitious compositions or extruded building products may continue to hydrate or cure long after they have attained significant hardness and a substantial amount of their maximum strength.

The terms "green," "green material," "green extrudate," or "green state" are meant to refer to the state of a cementitious composition which has not yet achieved a substantial amount of its final strength; however, the "green state" is meant to identify that the cementitious composition has enough cohesiveness to retain an extruded shape before being hydrated or cured. As such, a freshly extruded extrudate comprised of hydraulic cement and water should be considered to be "green" before a substantial amount of hardening or curing has taken place. The green state is not necessarily a clear-cut line of demarcation as to the amount of curing or hardening that has taken place, but should be construed as being the state of the composition prior to being substantially cured. Thus, a cementitious composition is in the green state post extrusion and prior to being substantially cured.

The term "form-stable" is meant to refer to the condition of a green extrudate immediately upon extrusion which is characterized by the extrudate having a stable structure that does not deform under its own weight. As such, a green extrudate that is form-stable can retain its shape during handling and further processing. The term "composite" is meant to refer to a form- stable composition that is made up of distinct components such as fibers, rheology-modifiers, cement, aggregates, set accelerators, and the like. As such, a composite is formed as the hardness or form-stability of the green extrudate increases, and can be prepared into a building product. The term "dry weight" is meant to refer to the composition being characterized without the presence of water or other equivalent solvent or hydrating reactant. For example, when the relative concentrations are expressed in percentages by dry weight, the relative concentrations are calculated as if there were no water. Thus, the dry weight is exclusive of water. The term "wet weight" is meant to refer to the composition being characterized by the moisture content that arises from the presence of water. For example, the relative concentration for wet weight of a component is measured by a total weight that includes the water and all other compositional components.

The term "nail acceptance" is meant to refer to the ease of hammering a nail into a cementitious building product. The nail acceptance is described by a numerical range that is defined as follows: 1 refers to a building product into which a nail can be easily hammered without bending; 2 refers to a building product of greater hardness such that a nail can be hammered without bending but that requires greater skill and substantially downward pressure to prevent bending; 3 refers to a building product having a high level of hardness such that a nail is typically bent or deformed using normal hammering action (but which can accept a straight nail if a conventional nail gun having high force is used).

As used herein, the term "pullout resistance" is meant to refer to the amount of force or pressure required to extract a fastening rod, such as a nail or screw, from a substrate such as wood, concrete, and the inventive cementitious building product. Also, pullout resistance can be calculated by the force required to extract a 1Od (e.g., 10 penny nail) nail imbedded 1 inch into the cured cementitious composite. The pullout resistance is proportional to the fiber content, all things being equal.

As used herein, the term "fastening rod" is meant to refer to a nail, screw, bolt, or the like that is configured to form a hole within a substrate while being inserted therein. Such insertions can be performed by hammering, screwing, ballistics, and the like. Additionally, the fastening rod can be used to fasten one member to another member by the fastening rod forming holes as it is being inserted within each member.

The building products of the present invention can typically be drilled using ordinary wood drill bits and/or sawed using ordinary wood saws, unlike conventional concrete products which require masonry bits and saw blades. In view of the foregoing definitions, the following discussion sets forth the inventive features of embodiments of the present invention. π. Compositions Used to Make Extruded Building Products

The extrudable cementitious compositions used to make extruded building products in accordance with the present invention include water, hydraulic cement, fibers, a rheology modifying agent, and optionally a set accelerator and/or an aggregate. The cementitious building products are formulated so as to have less hardness and compressive strength compared to ordinary concrete, and have greater flexibility, softness, elongation, toughness, and deflection in order to better imitate the properties of real wood. In general, the ratio of tensile to compressive strength of the inventive cementitious composites will be much higher than conventional concrete.

Moreover, the extrudable cementitious compositions and extruded building products prepared therefrom can have some components that are substantially the same as in other multi-component compositions discussed elsewhere. Accordingly, supplemental information on the individual components of such multi-component compositions and mixtures as well as some aspects of methods used to manufacture extruded articles and calandered articles therefrom can be obtained in U.S. Patent Nos. 5,508,072, 5,549,859, 5,580,409, 5,631,097, and 5,626,954, and U.S. Patent Application No. 60/627,563, which are incorporated herein by reference. It should be understood, however, that the building products of the present invention are substantially stronger and have greater flexural stiffness compared to paper-like sheet products manufactured using hydraulic cement but wherein such sheets were completely dried out in a manner of seconds or minutes using a Yankee roller heated significantly above the boiling point of water (e.g., 15O-3OO°C). Rapid evaporation of water interferes with hydration of hydraulic cement, thereby converting it into a particulate filler rather than a binder. Controlled evaporation of water over a period of several days (at least about 2 days) at a temperature below the boiling point of water (e.g., 100-175⁰F, or about 40-80°C) removes excess water while still allowing hydration of the hydraulic cement binder. The building products according to the invention are as different from paper-like sheets make using cement as two-by-fours and other wood building products are from ordinary tree paper.

In one embodiment, the calendering equipment and processes described in the incorporated references can be used with the compositions described herein. However, the nip distance between calenders may be adjusted to produce boards or other products that are a size to be used as cementitious building products (i.e., at least about 1/8 inch, preferably at least 1/4 inch, more preferably at least Vi inch, and most preferably at least 1 inch) (at least about 2 mm, preferably at least about 5 mm, more preferably at least about 1.25 cm, and most preferably at least about 2.5 cm). For example, the process described in U.S. Pat. No. 5,626,954 can be modified to calender larger materials so as to produce wood-like boards, such as two-by-fours, one-by-tens, and the like. Also, the benefits of the calendering process can be used to prepare wood-like boards of any length, such as lengths that are essentially impossible to obtain from real wood. This can allow for the inventive wood-like boards to be manufactured to have custom cross-sectional areas and lengths, such as lengths of 8 ft 8 in, 40 ft, 60 ft, and 80 ft. A. Hydraulic Cement

The extrudable cementitious compositions and the cementitious building products include one or more types of hydraulic cement. As discussed below, while the rheology- modifier can contribute a majority of the strength to the extrudable composition and green extrudate, the hydraulic cement can contribute a majority of the strength to the cementitious composite or building product after curing or hydrating begins. Examples of hydraulic cements and associated properties and reactions during the entire manufacturing process as well as in the finished fiber-reinforced building product can be found in the incorporated references. For example, the hydraulic cement can be white cement, grey cement, aluminate cement, Type I-V cement, and the like. The extrudable composition can include various amounts of hydraulic cement.

Usually, the amount of hydraulic cement in an extrudable composition is described as a wet percentage (e.g., wet weight % or wet volume %) so as to account for the water that is present. As such, the hydraulic cement can be present from about 25% to about 75% by wet weight, more preferably from about 35% to about 65% by wet weight, and most preferably from about 40 to 60% by wet weight of the extrudable composition.

Briefly, within the extruded product, the hydraulic cement forms a cement paste or gel by reacting with water, where the speed of the reaction can be greatly increased through the use of set accelerators, and the strength and physical properties of the cementitious building product are modulated by a high concentration of fibers. Usually, the amount of hydraulic cement in a cured cementitious composite is described as a dry percentage (e.g., dry weight % or dry volume %). The amount of hydraulic cement can vary in a range from about 40% to about 95% by dry weight, more preferably about 50% to about 80% by dry weight, and most preferably about 60% to about 75% by dry weight. It should be recognized that some products can use more or less hydraulic cement, as needed and depending on other constituent. The hydraulic cement, more specifically the cement or hydraulic paste formed by reacting or hydrating with water, will typically contribute at least about 50% of the overall binding strength of the inventive building products, preferably at least about 70%, more preferably at least about 80%, and most preferably at least about 90% of the overall binding strength. That is a direct result of maintaining a relative low effective water to cement ratio (e.g., by one or more of controlled early heating to slowly remove a portion of the water by evaporation and/or absorption of water by fibers and/or rheology modifying agent. B. Water In one embodiment, water can be used in relatively high amounts within the extrudable composition to increase the rate of mixing, extrudability, cure rate, and/or porosity of the finished extruded products. While adding more water has the effect of reducing compressive strength, this may be a desirable by-product in order to yield a product that can be sawed, sanded, nailed, screwed, and otherwise used like wood or as a wood substitute. Additionally, high concentrations of water in the extrudable composition or extrudate can be reduced by evaporation or heating. When water is evaporated from the green extrudate, form-stability and porosity can be increased simultaneously. This is in contrast to typical concrete compositions and methods, in which increasing porosity decreases green strength, and vice versa.

Accordingly, the amount of water within the various mixtures described herein can be drastically varied over a large range. For example, the amount of water in the extrudable composition and green extrudate can range from about 25% by wet weight to about 75% by wet weight, more preferably from about 35% to about 65%, and most preferably from about 40% to about 60% by wet weight. On the other hand, the cured composite or hardened building product can have free water at less than 10% by wet weight, more preferably less than about 5% by wet weight, and most preferably less than about 2% water by weight; however, additional water can be bound with the rheology-modifier, fibers, or aggregates.

The amount of water in the extrudate during the rapid reaction period should be sufficient for curing or hydrating so as to provide the finished properties described herein. Nevertheless, maintaining a relatively low water to cement ratio (i.e., w/c) increases the strength of the final cementitious building products. Accordingly, the actual or nominal water to cement ratio will typically initially range from about 0.75 to about 1.2. In some instances the actual or nominal water to cement ratio can be greater than 1.5 or 1.75 in order to yield building products having very high porosity and/or less hardness and increased sawability, nailability and/or screwability. The water to cement ratio affects the final strength of the hydraulic cement binder. Controlled removal of water by evaporation (e.g. , over a period of days, such as at least about two days) not only increases green strength in the short term, it can increase long term strength of the cement binder by reducing the water to cement ratio. Additionally, the water can be used to provide porosity to the finished product by being present during the forming process and then rapidly removing a portion of the water. The rapid removal of water can result in voids in the finished product so as to increase porosity. Also, this can decrease the water amount, increase the strength of the binder, and provide a correct strength ratio of water to binder. The water to cement ratio following controlled evaporation by heating will preferably be less than about 0.5 (i.e., in a range of about 0.1 to about 0.5, preferably about 0.2 to about 0.4, more preferably about 0.25 to about 0.35, and most preferably about 0.3).

The amount of water is also selected in order to yield a building product having a desired density. Because the ability to saw, nail or screw into cementitious building products according to the invention is related to the density (i.e., the lower the density, the easier it is to saw, nail and/or screw into the composite using ordinary wood working tools), the amount of water can be selected to yield a product having a desired level of porosity. In general, increasing the amount of water that is removed by evaporation prior to, during or subsequent to curing reduces the density of the final cured building product.

In the case where it is desirable for the building products to have properties similar to those of wood, it will be preferable for the density to be less than about 1.2 g/cm³, more preferably less than about 1.15 g/cm³, even more preferably less than about 1.1 g/cm³, and most preferably less than about 1.05 g/cm³.

Tn addition to having wood-like properties that allow for sawing, nailing and screwing using convention wood working tools, building materials according to the invention can be finished using a router and planer. C. Fibers

The extrudable composition and extruded building products include a relatively high concentration of fibers compared to conventional concrete compositions. Moreover, the fibers are typically substantially homogeneously dispersed throughout the cementitious composition in order to maximize the beneficial properties imparted by the fibers. The fibers are present in order to provide structural reinforcement to the extrudable composition, green extrudate, and the cementitious building product. Fibers also provide nail and screw hold by providing a spring back effect, imparting micro level toughness, preventing formation of cracks or catastrophic failure at the micro level around the hole formed by the nail or screw. Fibers that can absorb substantial quantities of water (e.g., wood, plant or other cellulose-based fibers) may be used to reduce the effective water/cement ratio (i.e., based on water that is actually available for cement hydration).

Various types of fibers may be used in order to obtain specific characteristics. For example, the cementitious compositions can include naturally occurring organic fibers extracted from hemp, cotton, plant leaves or stems, hardwoods, softwoods, or the like, fibers made from organic polymers, examples of which include polyester nylon (i.e., polyamide), polyvinylalcohol (PVA), polyethylene, and polypropylene, and/or inorganic fibers, examples of which include glass, graphite, silica, silicates, microglass made alkali resistant using borax, ceramics, carbon fibers, carbides, metal materials, and the like. The preferred fibers, for example, include glass fibers, woolastanite, abaca, bagasse, wood fibers (e.g., soft pine, southern pine, fir, and eucalyptus), cotton, silica nitride, silica carbide, silica nitride, tungsten carbide, and Kevlar; however, other types of fibers can be used.

The fibers used in making the cementitious compositions can have a high length to width ratio (or "aspect ratio") because longer, narrower fibers typically impart more strength per unit weight to the finished building product. The fibers can have an average aspect ratio of at least about 10:1, preferably at least about 50:1, more preferably at least about 100: 1, and most preferably greater than about 200:1.

In one embodiment, the fibers can be used in various lengths such as, for example, from about 0.1 cm to about 2.5 cm, more preferably from about 0.2 cm to about 2 cm, and most preferably about 0.3 cm to about 1.5 cm. In one embodiment, the fibers can be used in lengths less than about 5 mm, more preferably less than about 1.5 mm, and most preferably less than about 1 mm.

Tn one embodiment, very long or continuous fibers can be admixed into the cementitious compositions. As used herein, a "long fiber" is meant to refer to a thin long synthetic fiber that is longer than about 2.5 cm. As such, a continuous fiber can be present with lengths ranging from about 2.5 cm to about 10 cm, more preferably about 3 cm to about

8 cm, and most preferably from about 4 cm to about 5 cm.

The concentration of fibers within the extrudable cementitious compositions can vary widely in order to provide various properties to the extruded composition and the finished product. Generally, the fibers can be present in the extrudable composition in the range from about 2% to about 50% by wet weight within the composition, more preferably from about

5% to about 40%, and even more preferably from about 8% to about 30%, and most preferably about 10% to about 25% by wet weight.

The concentration of fibers within the cured cementitious composites can be in the range from about 3% to about 65% by dry weight, more preferably from about 5% to about 50%, and even more preferably from about 8% to about 40%, and most preferably about 10% to about 30% by dry weight.

In another embodiment, the fibers can be present at greater than about 10% by dry volume, preferably greater than about 15% by dry volume, more preferably greater than 20% by dry volume, even more preferably greater than about 25% by volume, and most preferably greater than about 30% by dry volume.

Additionally, specific types of fibers can vary in amount in the compositions. Accordingly, PVA can be present in a cured cementitious composition up to about 5% by dry weight, more preferably from about 1% to about 4%, and most preferably from about 2% to about 3.25%. Soft and/or woods can be present in a cured cementitious composition in amounts described above with respect to general fibers or present up to about 10% by dry weight, more preferably up to about 5% by dry weight, and most preferably up to about 3.5% by dry weight. Newspaper fibers can be present in a cured cementitious composition in amounts described above with respect to general fibers or present up to about 35% by dry weight, more preferably from about 10% to about 30% by dry weight, and most preferably from about 15% to about 25% by dry weight.

In one embodiment, the type of fiber can be selected based on the desired structural features of the finished product comprised of the cementitious building product, where it can be preferred to have dense synthetic fibers compared to light natural fibers or vice versa. Typically, the specific gravity of natural or wood fibers range from about 0.4 for cherry wood fibers to about 0.7 for birch or mahogany. On the other hand, synthetic fibers can have specific gravities that range from about 1 for polyurethane fibers, about 1.5 for Kevlar fibers, about 2 for graphite and quartz glass, about 3.2 for silicon carbide and silicon nitride, about 7 to about 9 for most metals with about 8 for stainless steel fibers, about 5.7 for zirconia fibers, to about 15 for tungsten carbide fibers. As such, natural fibers tend to have densities less than 1, and synthetic fibers tend to have densities from about 1 to about 15.

In one embodiment, various fibers of differing densities can be used together within the cementitious compositions. For example, it can be beneficial to combine the properties of a cherry wood fiber with a silicon carbide fiber. Accordingly, a combined natural/synthetic fiber system can be used at ratios ranging from about 10 to about 0.1, more preferably about 6 to about 0.2, even more preferably about 5 to about 0.25, and most preferably about 4 to about 0.5.

In one embodiment, a mixture of regular or long length fibers, such as pine, fir, or other natural fibers, may be combined with micro-fibers, such as woolastinite or micro glass fibers, to provide unique properties, including increased toughness, flexibility, and flexural strength, with the larger and smaller fibers acting on different levels within the cementitious matrix.

In view of the foregoing, the fibers are added in relatively high amounts in order to yield a cementitious building product having increased tensile strength, elongation, deflection, deformability, and flexibility. For example, the high amount of fibers yields a cementitious building product that can have a fastening rod inserted therein, with a pullout resistance that resists extraction. The fibers contribute to the ability of the cementitious building product to be sawed, screwed, sanded and polished like wood, or the nap of the fibers can be exposed by buffing to yield a suede-like or fabric-like surface. Additionally, the extrudable cementitious composition and cured cementitious composites can include saw dust. While saw dust may be considered to be fibrous, it is usually comprised of a plurality of fibers held together with lignin or other natural agglomerating material. Fibers can provide characteristics to the extrudable cementitious composition or cured cementitious composites that differ somewhat from the characteristics provided by true fibers. In some instances, saw dust can function as a filler. Saw dust can be obtained as a byproduct from lumber mills and other facilities where lumber or wood products are cut or milled. The extrudable cementitious composition can include saw dust up to 10% by wet weight, preferably up to 15% by wet weight, more preferably up to 20% by wet weight, and most preferably from about 10% to about 20% by wet weight. Accordingly, the cured cementitious composites can include saw dust up to 12% by dry weight, preferably up to 18% by dry weight, more preferably up to 25% by dry weight, and most preferably from about 12 to about 20% by dry weight. D. Rheology Modifying Agent In preferred embodiments of the present invention, the extrudable cementitious compositions and the cementitious building products include a rheology-modifying agent ("rheology-modifier"). The rheology-modifier can be mixed with water and fibers to aid in substantially uniformly (or homogeneously) distributing the fibers within the cementitious composition. Additionally, the rheology-modifier can impart form- stability to an extrudate. In part, this is because the rheology-modifier acts as a binder when the composition is in a green state to increase early green strength so that it can be handled or otherwise processed without the use of molds or other shape-retaining devices. The rheology-modifying agent helps control porosity (is., yields uniformly dispersed pores when water is removed by evaporation). Further, the rheology-modifying agent can impart increased toughness and flexibility to a cured composite which can result in enhanced deflection characteristics. Thus, the rheology-modifier cooperates with other compositional components in order to achieve a more deformable, flexible, bendable, compactable, tough, and/or elastic cementitious building product.

For example, variations in the type, molecular weight, degree of branching, amount, and distribution of the rheology-modifier can affect the properties of the extrudable composition, green extrudate, and cementitious building products. As such, the type of rheology-modifier can be any polysaccharide, proteinaceous material, and/or synthetic organic material that is capable of being or providing the rheological properties described herein. Examples of some suitable polysaccharides, particularly cellulosic ethers, include methylhydroxyethylcellulose, hydroxymethylethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, and hydroxyethylpropylcellulose, starches such as amylopectin, amylose, starch acetates, starch hydroxyethyl ethers, ionic starches, long-chain alkylstarches, dextrins, amine starches, phosphate starches, and dialdehyde starches, polysaccharide gums such as seagel, alginic acid, phycocolloids, agar, gum arabic, guar gum, locust bean gum, gum karaya, gum tragacanth, and the like. Examples of some proteinaceous materials include collagens, caseins, biopolymers, biopolyesters, and the like. Examples of synthetic organic materials that can impart rheology-modifying properties include petroleum-based polymers (e.g., polyethylene, polypropylene), latexes (e.g., styrene-butadiene), and biodegradable polymers (e.g., aliphatic polyesters, polyhydroxyalkanoates, polylactic acid, polycaprolactone), polyvinyl chloride, polyvinyl alcohol, and polyvinyl acetate. Clay can also act as a rheology-modifier to aid in dispersing the fibers and/or imparting form stability to the green extruded composition.

The amount of rheology-modifier within the extrudable composition and cementitious building product can vary from low to high concentrations depending on the type, branching, molecular weight, and/or interactions with other compositional components. For example, the amount of rheology-modifier present in the extrudable cementitious compositions can range from about 0.1% to about 10% by wet weight, preferably from about 0.25% to about 5% by wet weight, even more preferably about 0.5% to about 5%, and most preferably from about 1% to about 3% by wet weight. The amount of rheology-modifier present in the cured cementitious compositions can range from about 0.1% to about 20% by dry weight, more preferably from about 0.3% to about 10% by dry weight, even more preferably about 0.75% to about 8%, and most preferably about 1.5% to about 5% by dry weight.

Additionally, examples of synthetic organic materials, which are plasticizers usually used along with the rheology-modifier, include polyvinyl pyrrolidones, polyethylene glycols, polyvinyl alcohols, polyvinylmethyl ethers, polyacrylic acids, polyacrylic acid salts, polyvinylacrylic acids, polyvinylacrylic acid salts, polyacrylimides, ethylene oxide polymers, polylactic acid, synthetic clay, styrene-butadiene copolymers, latex, copolymers thereof, mixtures thereof, and the like. For example, the amount of plasticizers in the composition can range from no plasticizer to about 40% plasticizer by dry weight, more preferably about 1% to about 35% plasticizer by dry weight, even more preferably from about 2% to about 30%, and most preferably from about 5% to about 25% by dry weight.

The rheology modifying agent will typically impart less than 50% of the overall binding strength of the inventive building products. They may indirectly increase the strength of the cement paste, however, by reducing the effective water/cement ratio. Water that is bound by the rheology modifying agent is not generally readily available for hydration of the hydraulic cement binding, thereby reducing the overall amount of water that is available for cement hydration. E. Filler In one embodiment, the extrudable composition, green extrudate, and cured cementitious composite can include fillers. Alternatively, there are instances where filler materials are specifically excluded. Fillers, if used at all, are generally included in smaller amounts and mainly to decrease the cost of the extruded products. Because it is desired to obtain extruded products in the form of wood-like building material having the properties of wood, fillers should be selected that do not yield a product that is too hard and difficult to work with. Examples, of fillers include expanded clays, perlite, vermiculite, kaolin, wollastonite, diatomaceous earth, limestone, plastic spheres, glass spheres, granulated rubber, granulated plastic, exfoliated vermiculite, talk, mica, and course sand are more preferable because they decrease the weight and density of the cementitious building product. Some fillers, such as vermiculite and plastic spheres, have elasticity, and can provide elastic spring-back to provide better gripping strength to a fastening rod. Others, such as perlite and glass spheres, are friable, which causes or allows them to be crushed when driving in a fastening rod, thereby increasing or providing friction to resist pullout. Additional information regarding the types and amounts of fillers that can be used in the cementitious compositions can be obtained in the incorporated references. Fillers such as exfoliated vermiculite, talk and mica can be platelet shaped, and can longitudinally align within the green extrudate by the extruder.

In one embodiment, the extrudable cementitious compositions can include a widely varying amount of fillers. Specifically, when used, fillers can each independently be present at less than about 10% by wet weight, preferably less than about 7% by wet weight, more preferably less than about 3% by wet weight, and most preferably between about 2% to about 12% by wet weight.

In one embodiment, the cured cementitious compositions can include a widely varying amount of fillers. Specifically, when used, fillers can each independently be present at less than about 15% by dry weight, preferably less than about 10% by dry weight, more preferably less than about 5% by dry weight, and most preferably between about 3% to about 15% by dry weight. In some instances, fillers such as limestone can be present up to about 70% by dry weight. For example, when included in a cured cementitious composition, vermiculite can be present from about 2% by dry weight to about 20% by dry weight, and preferably from about 3% by dry weight to about 16% by dry weight. F. Other Materials

In one embodiment, a set accelerator can be included in the extrudable composition, green extrudate, and cementitious building product. As described herein and in the incorporated references, the set accelerator can be included so as to decrease the duration of the induction period or hasten the onset of the rapid reaction period. Accordingly, traditional set accelerators such as MgCl₂, NaCCH, KCO₃ CaCl₂ and the like can be used, but may result in a decrease in the compressive strength of the cementitious building product; however, this may be a desirable by-product in order to yield a product that can be sawed, sanded, nailed, and screwed like wood. For example, the traditional set accelerators can be present in the green extrudate from about 0.001% to about 5% by total dry weight, more preferably from about 0.05% to about 2.5% by dry weight, and most preferably from about 0.11% to about 1% by dry weight.

Tn one embodiment, the set accelerator includes a calcium-silica-hydrate (C-S-H). The C-S-H can be prepared by forming a CaO-SiO₂-H₂O precipitate by adding together aqueous solutions of Ca(NOs)₂ and NaSiθ₃ at room temperature and forming a precipitate. Additional details of the preparation and use of such a C-S-H set accelerator can be obtained in U.S. Provisional Application No. 60/627,563, previously incorporated by reference. Additionally, an increase in the amount of C-S-H set accelerator may not substantially decrease the compressive strength of the cementitious building product. For example, C-S-H can be present in the green extrudate from about 0.01% to about 15% by total dry weight, more preferably from about 0.5% to about 10% by dry weight, and most preferably from about 1% to about 5% by dry weight. Thus, the amount of C-S-H set accelerator admixed into the extrudable composition can be greater than the amount of traditional set accelerators without compromising the strength of the finished product. Additionally, it can be favorable to combine the properties of traditional set accelerators with C-S-H, where the traditional set accelerator to C-S-H ratio can range from about 0.2 to about 5, more preferably from about 0.25 to about 4, and most preferably from about 0.5 to about 2. Alternatively, the amount of C-S-H set accelerator or the corresponding concentrations of calcium and silicate can be maintained or only slightly varied throughout the induction period and the rapid reaction period so as to remain substantially constant in the final cured cementitious building product.

In one embodiment, the cementitious compositions can include an additive material. Alternatively, there are instances where additive materials are specifically excluded. The additives, if used at all, are generally included in smaller amounts and mainly to decrease the cost of the extruded products. In some instances, the additives can be used to modify the strength of the cured product. Some examples of additives can be pozzolanic materials that react with water, have a high pH, and are somewhat cementitious. Examples of pozzolanic materials include pozzolanic ash, slade, fly ash, silica fume, and the like.

Additionally, the cementitious compositions can include dyes or pigments to alter the color or provide custom-colored cementitious composite products. Dyes or pigments that are routinely used in cementitious compositions can be applied to the present invention.

Other specific materials that can be present in the cementitious compositions can include guar gum, darauair, TiO₂, delvo, glenium 30/30, LatexAc 100, pozzilith NC534, and other similar materials. For example, TiO₂ can be present from about 0.5% to about 1.5% dry weight, preferably from about 0.7% to about 1.3% by dry weight; delvo can be present from about 0.05% to about 0.5% by dry weight, preferably from about 0.06% to about 0.37% by dry weight; glenium 30/30 can be present from about 0.25% to about 0.5% by dry weight, preferably from about 0.3% to about 0.4% by dry weight; LatexAc 100 can be present from about 0.75% to about 3% by dry weight, preferably from about 0.95% by dry weight to about 2.80% by dry weight; and pozzilith JSIC534 can be present from about 1.25% to about 2% by dry weight, preferably from about 1.4% to about 1.5% by dry weight.

In one embodiment, the cementitious compositions can include additional optional materials such as dispersants, polymeric binders, nucleating agents, volatile solvents, salts, buffering agents, acidic agents, coloring agents, and the like. Specifically, when used, these additional optional materials, some of which are discussed in the incorporated references, can each independently be present at less than about 10% by dry weight, more preferably less than about 5% by dry weight, and most preferably less than about 1% by dry weight. In one embodiment, a substantially cured cementitious extrudate that is reinforced with fibers can be coated with a protective or sealing material such as a paint, stain, varnish, texturizing coating, and the like. As such, the coating can be applied to the cementitious building product after it is substantially cured. For example, the cementitious building product can be stained so that the fibers present on the surface are a different shade from rest of the product, and/or texturized so as to resemble a wooden product.

Sealants known in the concrete industry can be applied to the surface and/or incorporated into the cementitious matrix in order to provide waterproofing properties. These include silanes and siloxanes. In addition, C-S-H particles can be applied to the surface and/or mixed into the matrix to provide a waterproofing feature. Precipitated hydrated cement paste can also be applied to the surface to provide waterproofing or other protection. JH. Manufacturing Building Products

Figure 1 is a schematic diagram that illustrates an embodiment of a manufacturing system and equipment that can be used during the formation of an extrudable composition, green extrudate, cementitious composite, and/or building product. It should be recognized that this is only one example illustrated for the purpose of describing a general processing system and equipment, where various additions and modifications can be made thereto in order to prepare the inventive cementitious compositions and building products. Also, the schematic representation should not be construed in any limiting manner as to the presence, arrangement, shape, orientation, or size of any of the features described in connection therewith. With that said, a more detailed description of the system and equipment that can prepare the cementitious compositions as well as cementitious building products that are in accordance with the present invention is now provided. Referring now to Figure IA, which depicts an embodiment of an extrusion system 10 in accordance with the present invention. Such an extrusion system 10 includes a first mixer 16, optional second mixer 18, and an extruder 24. The first mixer 16 is configured to receive at least one feed of materials through at least a first feed stream 12 for being mixed into a first mixture 20. After adequate mixing, which can be performed under high shear, while maintaining a temperature below that which accelerates hydration, the first mixture 20 is removed from the first mixer 16 as flow of material ready for further processing.

By mixing the first mixture 20 apart from any additional components, the respective mixed components can be homogeneously distributed throughout the composition. For example, it can be advantageous to homogeneously mix the fibers with at least the rheology- modifier and water before combining them with the additional components. As such, the rheology-modifier, fibers, and/or water are mixed under high shear so as to increase the homogeneous distribution of fibers therein. The rheology modifying agent and water form a plastic composition having high yield stress and viscosity that is able to transfer the shearing forces from the mixer down to the fiber level. In this way, the fibers can be homogeneously dispersed throughout the mixture using much less water than required in the Hatschek and traditional paper-making procedures, which typically require up to 99% water to disperse the fibers.

The optional second mixer 18 has a second feed stream 14 that supplies the material to be mixed into a second mixture 22, where such mixing can be enhanced by the inclusion of a heating element. For example, the second mixer 18 can receive and mix the additional components, such as the additional water, set accelerators, hydraulic cement, plasticizers, aggregates, nucleating agents, dispersants, polymeric binders, volatile solvents, salts, buffering agents, acidic agents, coloring agents, fillers, and the like before combining them with other components to form an extrudable composition. The second mixer 18 is optional because the additional components could be mixed with the fibrous mixture in the first mixer 16.

As in the illustrated schematic diagram, the extruder 24 includes an extruder screw 26, optional heating elements (not shown), and a die head 28 with a die opening 30. Optionally, the extruder can be a single screw, twin screw, and/or a piston-type extruder. After the first mixture 20 and second mixture 22 enter the extruder they can be combined and mixed into an extrudable composition.

By mixing the components, an interface is created between the different components, such as the rheology-modifying agent and fibers, which allows for individual fibers to pull apart from each other. By increasing the viscosity and yield thrust with the rheology- modifying agent, more fibers can be substantially homogenously distributed throughout the mixture and final cured product. Also, the cohesion between the different can be increased so as to increase inter-particle and capillary forces for enhanced mixing and form-stability after extrusion. For example, the cohesion between the different components can be likened to clay so that the green extrudate can be placed on a pottery wheel and worked similar to common clays that are fabricated into pottery.

In one embodiment, additional feed streams (not shown) can be located at any position along the length of the extruder 24. The availability of additional feed streams can enable the manufacturing process to add certain components at any position so as to modify the characteristics of the extrudable composition during mixing and extruding as well as the characteristics of the green extrudate after extrusion. For example, in one embodiment it can be advantageous to supply the set accelerator into the composition within about 60 minutes to within about 1 second before being extruded, especially when it is C-S-H. More preferably, the set accelerator is mixed into the composition within about 45 minutes to about 5 seconds before being extruded, even more preferably within about 30 minutes to about 8 seconds, and most preferably within about 20 minutes to about 10 seconds before being extruded. This can enable the green extrudate to be configured for increased form- stability and a shortened induction period before the onset of the rapid reaction period.

Accordingly, the post-extrusion induction period can be substantially shortened so as to induce the onset of the rapid reaction period to begin within about 30 seconds to about 30 minutes after being extruded, more preferably less than about 20 minutes, even more preferably less than about 10 minutes, and most preferably less than about 5 minutes after being extruded.

In another embodiment, the set accelerator can be separately supplied into the extruder from the other components so that the induction period has a duration of less than about 2 hours, more preferably less than 1 hour, even more preferably less than about 40 minutes, and most preferably less than 30 minutes.

With continuing reference to Figure IA, as the cementitious composition moves to the end of the extruder 24, it passes through the die head 28 before being extruded at the die opening 30. The die head 28 and die opening 30 can be configured into any shape or arrangement so long as to produce an extrudate that is capable of being further processed or finished into a building product. In the illustrated embodiment, it can be advantageous for the die opening 30 to have a circular diameter so that the extrudate 32 has a rod-like shape. Other exemplary cross-sectional shapes are illustrated in Figure 1C, including hexagonal 42, rectangular 44, square 46, or I-beam 48. The extruded building products can be characterized as being immediately form- stable while in the green state. That is, the extrudate can be immediately processed without deforming, wherein the processing can include cutting, sawing, shaping, milling, forming, drilling, and the like. As such, the extrudate in the green state does not need to be cured before being prepared into the size, shape, or form of the finished cementitious building product. For example, the green-state processing can include the following: (a) creating boards, by milling, sawing, cutting, or the like, that have specified dimensions, such as width, thickness, length, radius, diameter, and the like; (b) bending the extrudate so as to form a curved cementitious product, which can be of any size and shape, such as, a curved chair leg, curved arches, and other ornamental and/or structural members; (c) creating boards having lengths that exceed or are different from standard wood board lengths, which can include shorter or longer board lengths of 6 ft 9 in, 8 ft 8 in, 9 ft 1 in, 27 ft, 40 ft, 41 ft, 60 ft, 61 ft, 80 ft, 81 ft, and the like; (d) texturizing with rollers, which can impart wood grain-like surfaces to the cementitious building product; (e) having the surface painted, waterproofed, or otherwise coated, which can apply coatings comprised of silanes, siloxanes, latex, C-S-H, and the like; and (f) transported, shipped, or otherwise moved and/or handled. Also, the byproducts that are produced from the green-state processing can be placed into the feed compositions and reprocessed. Thus, the green cementitious byproducts can be recycled, which can significantly reduce manufacturing costs.

Figure IB is a schematic diagram of a die head 29 that can be used with the extrusion process of Figure IA. As such, the die head 29 includes a die opening 30 that has a hole forming member 31. The hole forming member 31 can be circular as shown, or have any cross-sectional shape. As such, the hole forming member 31 can form a hole in the extrudate, which is depicted in Figure 1C. Since the extrudate can be form-stable immediately upon extrusion, the hole can retain the size and shape of the hole forming member 31. Additionally, various die heads having hole forming members that can produce annular extrudates are well known in the art and can be adapted or modified, if needed, to be usable with the extrusion processes in accordance with the present invention.

With reference now to Figure 1C, additional embodiments of extrudates 40 are depicted. Accordingly, the die head and die opening of Figure IA or IB can be modified or altered so as to provide extrudates 40 having various cross-sectional areas, where the extrudate 40 cross-sectional area can be substantially the same as the cross-sectional area of the die opening. For example, the cross-sectional area can be a hexagon 42, rectangle 44 (e.g., two-by-four, one-by-ten, etc.), square 46, T-beam 48, or a cylinder 50, optionally having a continuous hole 49. Also, additional cross-sectional shapes can be prepared via extrusion. More particularly, the die head and die opening of Figure IB can be used so that the hexagon 42, rectangle 44 (e.g., two-by-four, one-by-ten, etc.), square 46, I-beam 48, or cylinder 50 can optionally include continuous circular holes 51, rectangular holes 53, square holes 57, or the like. Also, complex, dies heads and openings can be used for preparing the cylinder 50 having the continuous hole 49 and a plurality of smaller holes 51. Moreover, any general cross-sectional shape can be further processed into a specific shape such as, for example, a two-by-four from a four-by-four square shape. Alternatively, the die orifice may yield oversized products that are later trimmed to the desired specifications in order to ensure greater uniformity.

Accordingly, the foregoing processes can be usable for extruding building products with one or more continuous holes. For example, a two-by-four or other board can be extruded having one or more holes into which rebar can be inserted, either while in a green state or after curing. In the case of a cured board, the rebar may be held in place within the hole using epoxy or other adhesive to provide strong bonding between the rebar and board. For example, the cylinder 50 of Figure 1C, as well as the other shapes, can be fabricated into large building structures, such as utility, telephone, or power line polls. These structures can optionally include a large interior opening 49 to reduce the mass and cost, along with smaller holes 51 in the wall to permit the insertion of strengthening rebar, as shown. In one embodiment, a telephone pole has an outer diameter of about fourteen inches, a wall thickness of about three inches, and an interior hole diameter of about eight inches. The plurality of spaced-apart half-inch holes can be provided within the three-inch wall in order to accommodate the placement of rebar.

In one embodiment, the extrudable composition is de-aired before being extruded. While some processes can employ a specific de-airing process to remove a substantial amount of air from the extrudable composition, other processes can remove the air by the mixing process that occurs in the extruder. In any event, the active or passive de-airing can provide an extrudate that does not have large air voids or cellular formations. For example, a de-aired cementitious composite can have a dry porosity from about 15% to about 60%, more preferably from about 20% to about 55%, and most preferably about 25% to about 50%. Thus, the extrudate and resulting cementitious building product can be fabricated so as to be substantially or completely devoid of any multi- cellular formations.

In one embodiment, the extrudable composition is aerated before being extruded. Some processes can employ an active aerating process to increase the amount of air in the extrudable composition and thereby form air voids or multi -cellular formations, wherein such processes can include blowing pressurized air into the composition within the extruder or by open air mixing. Other compositions can be passively aerated by simply not being actively de-aired. Additionally, rapidly removing water from the extrudate can also increase the porosity of the finished product, which can be performed in a dryer or other heating chamber. In any event, the active or passive aerating can provide an extrudate and/or cementitious building product that has small to large air voids or cellular formations. For example, an aerated cementitious composite can have a porosity from about 40% to about 75%, more preferably from about 45% to about 65%, and most preferably about 50% to about 60%. Thus, aerating or de-airing the extrudable composition can provide the ability to increase or decrease the density of the cementitious building product.

Accordingly, the porosity of a cementitious building product can be tailored to specific and custom needs. This can allow for the manufacturing process to be tailored to provide a porosity that correlates with the intended use of the cementitious building product. For example, wood-like boards can be configured to have higher porosities, which enable improved nailing, screwing, cutting, drilling, milling, sawing, and the like. As such, the increased porosity can be used to enhance the wood-like properties of the cementitious material. Thus, the porosity along with the fiber content can be modified to correlate with intended uses.

In one embodiment, the extrudate can be further processed in a dryer or autoclave. The dryer can be useful for drying the extrudate so as to remove excess water, which can increase porosity and/or form-stability. On the other hand, the extrudate can be processed through an autoclave in order to increase the rate of curing.

Figure 2 is a schematic diagram depicting an alternative extrusion process that can be used to prepare the cementitious building products in accordance with the present invention. As such, the extrusion process can be considered to use a roller-extrusion system 200 that uses rollers to extrude the wet cementitious material into a green extrudate. Such a roller- extrusion system 200 includes a mixer 216 configured to receive at least one feed of materials through a feed stream 212 for being mixed into a mixture 220. After adequate mixing, which can be performed as described herein, the mixture 220 is removed from the mixer 216 as flow of material ready for further processing.

The mixture 220 is then applied to a conveyor 222 or other similar transporter so as to move the material from the site of application. This allows the mixture to be formed into a cementitious flow 224 that can be processed. As such, the cementitious flow 224 can be passed under a first roller 226 that is set at a predefined distance from the conveyor 222 and having a predefined cross-sectional area with respect thereto, which can press or shape the cementitious flow 224 into a green extrudate 228. Optionally, the conveyor 222 can then deliver the green extrudate 228 through a first calender 230 comprised of an upper roller 230a and a lower roller 230b. The calender 230 can be configured to have a predefined cross-sectional area so that the green extrudate 228 is further shaped and/or compressed into a shaped green extrudate 242. Also, an optional second calender 240 comprised of a first roller 240a and a second roller 240b can be used in place of the first calender 230 or in addition thereto. A combination of calenders 230, 240 can be favorable for providing a green extrudate that is substantially shaped as desired. Alternatively, the first roller 226 can be excluded and the cementitious flow 224 can be processed through any number of calenders 230, 240.

Additionally, the shaped green extrudate 242, or other extrudate described here, such as from the process illustrated in Figure IA, can be further processed by a processing apparatus 244. The processing apparatus 244 can be any type of equipment or system that is employed to process the green extrudate materials as described herein. As such, the processing apparatus 244 can saw, mill, cut, bend, coat, dry or otherwise shape or further process the shaped green extrudate 242 into a processed extrudate 246. Also, the byproduct 260 obtained from the processing apparatus 244 can be recycled into the feed composition 212, or applied to the conveyor 222 along with the mixture 220. When the processing apparatus 244 is a dryer, the shaped green extrudate 242 can be heated to a temperature that rapidly removes water so as to form voids in the processed extrudate 246, which increases porosity. In one embodiment, the processed extrudate 246, or other extrudate described herein, can be cured by being processed through an autoclave 248 or dryer. As such, the autoclave 248 or dryer can elevate the temperature of the processed extrudate 246 and the surrounding humidity so as to induce the onset of the hydration reaction. Thus, the autoclave 248 or dryer can rapidly cure the processed extrudate 246 into a cured cementitious building product 250. For example, the autoclave 248 can provide a steam cure when operated at a temperature of about 60-65°C for about 24 hours in order to obtain 75% of the final strength. A conventional dryer can then be used to remove residual water.

Optionally, the extrudate can be covered in plastic and/or stored for a period of time to allow the extrudate to cure. This can allow the extrudate to harden over time in order to produce the requisite strength for the cured cementitious composite product. For example, after 28 days, the cured cementitious composite product can have about 80% of final strength, and can be placed in a dryer to remove residual water.

Tn another option, a combined curing/drying process can be used to cure and dry the extruded cementitious composite. For example, the combined curing/drying process can be performed at a temperature of 60-65⁰C for 48 hours in order to obtain about 80% of the final strength. However, larger blocks can take additional time in any curing and/or drying process.

In accordance with Figures 3A-D, the extrusion system depicted in Figure IA can be modified so as to be capable of extruding the extrudate around a supplemental supporting element or reinforcing member such as rebar (metal or fiberglass), wire, wire mesh, fabric, and the like. By co-extruding the cementitious composition with a reinforcing wire, fabric, or rebar the resulting cementitious building product can have greater deflection and bending strength before breaking. Alternatively, the roller-extrusion system 200 can be configured to prepare reinforced green bodies and cementitious building products as described below. With reference now to Figure 3 A, one embodiment of a co-extrusion system 300 is depicted. The co-extrusion system 300 includes at least two or more die heads 302a and 302b. The die heads 302a and 302b are oriented so that the respective die openings 303 a and 303b produce extrudate that intermingles together into a uniform extrudate 308. Additionally, the co-extrusion system 300 includes a means for placing a supplemental supporting element such as rebar 304 within the uniform extrudate 308, wherein the means can include a conveyor, pulley, dive mechanism, movable die head, rebar pushing mechanism, rebar pulling mechanism, and the like.

As depicted, the rebar 304 is passed between the first die opening 303 a and the second die opening 303b. This allows the rebar 304 to be at least partially or completely encapsulated within the uniform extrudate 308, wherein the encapsulated rebar 306 is shown by dashed lines. As depicted, the rebar 304 can have a first end 310 that is oriented past the die openings 303a and 303b before any extrudate is applied to the rebar 304 so that the first end 310 is not encapsulated. The naked rebar can enable the rebar to be pulled past the die openings 303 a and 303b, and facilitates easy manipulation and handling post-extrusion.

With reference now to Figure 3B, another embodiment of a co-extrusion system 320 is depicted. The co-extrusion system 320 includes a die head 322 and a means for supplying a wire or fabric mesh 324 into the extrudate 326 wherein the means can include a conveyor, pulley, dive mechanism, movable die head, mesh pushing mechanism, mesh pulling mechanism, and the like. As such, the means can continuously supply the mesh 324 to the die opening 321 so that the extrudate 326 is extruded around and encapsulates the mesh 324. The encapsulated mesh 328 is represented by the lines within the extrudate 326. Additionally, the mesh 324 can be supplied at a rate substantially equivalent with the rate of extrusion so that the reinforced extrudate is evenly formed. With reference now to Figure 3 C, another embodiment of a co-extrusion system 340 is depicted. The co-extrusion system 340 includes a die head 342 with a die opening 348. The die head 342 and die opening 348 are configured so that a supplemental supporting element 344 (i.e., at least one rebar) can be passed through the die head 342 via a channel 346. The channel 346 allows the rebar 344 to be passed through the die opening 348 via a channel opening 350. When the rebar 344 passes through the channel opening 350 it is encapsulated with the extrudate 352 so as to form encapsulated rebar 354.

With reference now to Figure 3D, another embodiment of a co-extrusion system 360 is depicted. The co-extrusion system 360 includes a die head 362 with a die opening 363 and an open mold 364. The open mold 364 is configured to include an open cavity 366 defined by the mold body 368. In use, the open mold 364 receives the supplemental supporting element 370 such as a wire or fabric mesh, plurality of rebar or wires within the open cavity 366. This allows for the extrudate 374 to be extruded onto and around the mesh 370 so as to form encapsulated mesh 376, as shown by the dashed lines within the extrudate 374. While the open mold 364 can be used to define the cross-sectional shape of the extrudate 374, it does not necessarily do so. This is because the co-extrusion system 360 can be configured such that the open mold 365 merely supports the mesh 376, and passes the mesh 370 past the die opening 363. Thus, the extrudate 374 can be self-supporting and encapsulate the mesh 370 within the open mold 364 or on some other feature such as a conveyor system, pulley, drive mechanism, movable die head, rebar pushing mechanism, rebar pulling mechanism, and the like (not shown).

Figure 4 is a schematic diagram illustrating another embodiment for structurally reinforcing a cementitious building product with a rebar-like structure. As such, the reinforcing process 400 can use rebar 402 prepared from any strengthening material such as metal, ceramic, plastic, and the like. The rebar 402 can then be processed through a processing apparatus 404 that applies a coating of epoxy 406 to the rebar 402. A cementitious building product 408 having continuous hole 410 formed therein, such as by the processes described in connection to Figure IB, can be obtained for receiving the epoxy 406 coated rebar 402. The epoxy 406 coated rebar 402 is then inserted into the hole 410. This can include driving, pressing, or otherwise forcefully pushing the epoxy 406 coated rebar 402 into the hole. Accordingly, the cementitious building product 408 having the rebar 402 can be significantly strengthen and structurally reinforced. Alternatively, the epoxy can be inserted into the hole 410 of the cementitious building product 408 before the rebar 402 is inserted therein. In one embodiment, the green extrudate with or without a supplemental supporting element can be further processed by causing or allowing the hydraulic cement within the green extrudate to hydrate or otherwise cure so as to form a solidified cementitious building product. As such, the cementitious building product can be prepared so as to be immediate form-stable after being extruded so as to permit the handling thereof without breakage. More preferably, the cementitious composition, or green extrudate can be form-stable within 15 minutes, more preferably within 10 minutes, even more preferably within 5 minutes, and most preferably within 1 minute after being extruded. The most optimized and preferred composition and processing can result in a green extrudate that is form-stable upon extrusion. The use of a rheology-modifying agent can be used to yield extrudates that are immediate form-stable even in the absence of hydration of the hydraulic cement binder. In order to achieve form-stability, the manufacturing process can either simply allow the green extrudate to sit and set without any additional processing or it can be caused to hydrate and/or set. When the manufacturing includes causing the green extrudate to hydrate, set or otherwise cure, the manufacturing system can include a dryer, heater or autoclave. The dryer or heater can be configured to generate enough heat to drive off or evaporate the water from the extrudate so as to increase its rigidity and porosity or induce the onset of the rapid reaction period. On the other hand, an autoclave can provide pressurized steam to induce the onset of the rapid reaction period.

In one embodiment, the green extrudate can be allowed or induced to initiate the rapid reaction period as described herein in addition to including a set accelerator within the cementitious composition. As such, the green extrudate can be induced to initiate the rapid reaction period by altering the temperature of the extrudate or changing the pressure and/or relative humidity. Also, the rapid reaction period can be induced by configuring the set accelerator to initiate the reactions within a predetermined period of time after being extruded.

In one embodiment, the preparation of a cementitious composite or building product can include substantially hydrating or otherwise curing the green extrudate into the cementitious building product within a shortened period, or a faster reaction rate, compared to conventional concretes or other hydraulically settable materials. As a result, the cementitious building product can be substantially cured or hardened, depending on the type of binder that is used, within about 48 hours, more preferably within about 24 hours, even more preferably within 12 hours, and most preferably within 6 hours. Thus, the manufacturing system and process can be configured in order to obtain fast cure rates so that the cementitious building product can be further processed or finished. In one embodiment, a curing or cured cementitious composition can be further processed or finished. Such processing can include sawing, sanding, cutting, drilling, and/or shaping the cementitious composition into a desired shape, wherein the composition lends to such shaping. Accordingly, when a cementitious building product is sawed, the fibers and rheology-modifier can contribute to the straight cut-lines that can be formed without cracking or chipping the cut surface or internal aspects of the material. This enables the cementitious building product to be a wood substitute because a two-by-four-shaped product can be purchased by a consumer and cut with standard equipment into the desired shapes and lengths.

In one embodiment, the form-stable green extrudate can be processed through a system that modifies the external surface of the product. One example of such a modifϊcation is to pass the green extrudate through a calender or series of rollers that can impart a wood-like appearance. As such, the cementitious building product can be a wood substitute having the aesthetic appearance and texture of wood. Also, certain colorants, dyes, and/or pigments can be applied to the surface or dispersed within the cementitious building product so as to achieve the color of various types of woods.

The green extruded building products can also be reshaped while in a green state to yield, for example, curved boards or other building products having a desired radius. This is a significant advantage over traditional wood products, which are difficult to curve and/or which must be milled to have a curved profile. In one embodiment, the cementitious building product can be sanded and/or buffed in a manner that exposes the fibers at the surface. Due to the high percentage of fiber in the product, a large number of fibers can be exposed at the surface. This can provide for interesting and creative textures that can increase the aesthetic qualities of the product. For example, the cementitious building product can be sanded and buffed so that it has a suede- or fabric-like appearance and texture. IV. Building Products

The present invention provides the ability to manufacture cementitious building products having virtually any desired size and shape, whether extruded in the desired shape or later cut, milled or otherwise formed into the desired size and shape. Examples include trim board, two-by-fours, other sizes of lumber, paneling, imitation plywood, imitation fiber board, doors, shingles, moldings, table tops, table legs, window frames, door casing, roofing tiles, wall board, kick plates, beams, I-beams, floor joists, and the like. Accordingly, the cementitious building product can be load bearing (e.g., two-by-fours) or non-load bearing (e.g., trim board). Thus, the cementitious building product can be used as a wood substitute for almost any building application.

The cured cementitious composite can be configured to have various properties in order to function as a lumber substitute. An example of a cured cementitious composite that can function as a lumber substitute can have any of the following properties: capable of receiving nails by hammer and/or ballistics; capable of retaining or holding the nails, especially when being connected to another object; capable of receiving screws by screwdriver or mechanical screwing device; capable of retaining or holding the screws, especially when being connected to another object; being similar in weight to a lumber product, but can be somewhat heavier; strong enough not to fracture when dropped; strong enough not to significantly deflect at ends or fracture when held or supported at the middle; and/or capable of being sawed or cut with a hand saw or other saw configured for cutting wood.

In one embodiment, the green extrudate or cementitious composite can be prepared into a building product as described above. As such, a de-aired embodiment of the cured cementitious composite material can be characterized by having a specific gravity inclusive of pores or cellular formations can be greater than 0.85 or range from about 0.85 to about 2.0, more preferably from about 0.9 to about 1.75, and most preferably about 0.95 to about 1.5. However, in some embodiments a de-aired composite can have specific gravity greater than 2.0 when synthetic fibers are utilized. On the other hand, when not de-aired, the specific gravity of the cured composite inclusive of pores or cellular formations can be greater than about 0.4 or range from about 0.4 to about 0.85, more preferably from about 0.5 to about 0.75, and most preferably about 0.6 to about 0.75.

One embodiment of the cured composite can be characterized by having a compressive strength greater than about 1,500 psi, more preferably greater than about 1,750 psi, and more preferably greater than about 2,000 psi.

In one embodiment, the cured composite can have a flexural strength from about 160,000 psi to about 850,000 psi, preferably from about 200,000 psi to about 800,000 psi, more preferably from about 3,000 psi to about 700,000 psi, and most preferably from about 400,000 psi to about 600,000 psi. In one embodiment, the cured composite can have a flexural modulus from about

200,000 psi to about 5,000,000 psi, more preferably from about 300,000 psi to about 3,000,000 psi, and most preferably from about 500,000 psi to about 2,000,000 psi.

Tn one embodiment, the cured composite can have an elastic energy absorption from about 5 lbf-in to about 50 lbf-in, preferably from about 10 lbf-in to about 30 lbf-in, more preferably from about 12 lbf-in to about 25 lbf-in, and most preferably from about 15 lbf-in to about 20 lbf-in.

Additionally, the cementitious building product can be distinguished from prior concrete building products. Figure 5A depicts a representation of the problems that may arise from inserting (e.g., hammering, driving, or ballistic force) a fastening rod 64 (e.g., nail or screw) into the surface 62 of such a prior concrete building product 60, wherein the fastening rod 64 forms the hole 66 during insertion. Similar to ordinary concretes that are used in a variety of applications ranging from driveways to foundations, when the concrete 60 has a fastening rod 64 inserted therein, the structure of the surface 62 is damaged. As depicted, the concrete 60 and/or surface 62 are prone to forming cracks 68 and divots 70 from chipping around the hole 66. Since the concrete 60 is damaged around the hole 66, the surface of the hole 66 can appear to have an irregular and fractured shape formed by substantial crack, divots, and/or chips. Additionally, the force required to insert a nail fastening rod 64 into concrete with a hammer from repeatedly striking the head of the nail 64 often damages or bends the nail 64 so that it is essentially useless. Additionally, when the fastening rod 64 is a screw, the screwing action can bore a hole 66 in the surface that is riddled with cracks and chips. Thus, prior concrete building products 60 have not been suitable wood substitutes with respect to being capable of receiving a fastening rod 64, and have resembled and behaved similar to ordinary concrete by cracking and chipping during such an insertion. Referring now to Figure 5B, a representation of a cementitious building product 80 being used as a wood substitute in accordance with the present invention is depicted. Accordingly, the results of inserting a fastening rod 84 (e.g., nail or screw) into the surface 82 of the cementitious building product 80 are more favorable compared to the ordinary concrete of Figure 5A. More specifically, when a fastening rod 84 is inserted into the surface 82, the resulting hole 86 formed by the fastening rod 84 can be substantially round in shape. While there may be minor chipping or cracking as commonly occurs during such insertions into wood, the hole 86 is much more round and less damaged compared to the results of ordinary concrete. Since the cementitious building product 80 is configured as a wood substitute, a nail fastening rod 84 can be hammered therein by repeatedly striking the nail head without damaging or bending the nail 84.

In any event, the cementitious building products described herein can be used as wood substitute, and can even have a fastening rod inserted therein. As such, the inventive cementitious building products can be used to connect multiple pieced-together components or be used for other applications typical for a nail or screw. Furthermore, Figures 6A and 6B depict another representation 90 of the common results that occur when a fastening rod 94 (e.g., nail or screw) is inserted into a prior or ordinary concrete building product 92. When the fastening rod 94 is inserted into the surface 96 of the concrete 92, a hole 95 formed by the insertion is fractured and jagged as shown in Figure 4. Accordingly, in Figure 6 A the representation 90 depicts a longitudinal cut-away view of the resulting damage to the ordinary concrete 92, and in Figure 6B the representation 90 depicts a mid-level cross-sectional view of the resulting damaged hole 95.

As shown, the fastening rod 94 causes not only the surface 96 to crack or form divots 98, but the internal surface 100 of the entire length of the hole 95 is similarly damaged. More particularly, inserting the fastening rod 94 causes the internal surface 100 to be riddled with cracks 102, crushed concrete 104, and chipped concrete 106. Even though it is possible to insert a fastening rod 94 into concrete, it often requires some sort of ballistic or explosive charge instead of a hammering or screwing because ordinary hammering often results in bending a nail fastening rod 94 and screwing significantly damages the internal surface 100.

Additionally, a fastening rod 94 that has been inserted into ordinary concrete 92 can be easily extracted therefrom, often without the use of a tool or device as described above. Briefly, this is because the damage to the inner surface 100 decreases the compressive forces applied against the fastening rod 94 that are needed to hold it in place. As such, ordinary concrete 92 has a small or low pullout resistance, and a nail or screw 94 can be easily extracted therefrom. This does not allow the ordinary concrete 92 to be used as wood substitutes, and two such pieces cannot be properly nailed together without easily being pulled apart.

Furthermore, Figures 7 A and 7B depict a representation 110 of common results for a fastening rod 112 being inserted into a fiber-reinforced cementitious building product 114 in accordance with the present invention. In contrast to the representation in Figures 6A and 6B, when the fastening rod 112 is inserted into the surface 115 of the inventive building product 114, a hole 116 formed by the insertion is not damaged or substantially fractured, which is also shown in Figure 5. Accordingly, Figure 7 A depicts a longitudinal cut-away view of the resulting hole 116, and Figure 7B depicts a mid-level cross-sectional view of the resulting hole 116. As shown, the fastening rod 112 does not cause any substantial damage to the surface

115, or the internal surface 118 of the entire length of the hole 116. More particularly, inserting the fastening rod 112 can cause fibers 120 at the internal surface 118 to become exposed and deformed or pushed aside by the fastening rod 1 12. As described, these fibers 120 are deformed or pushed aside to allow the fastening rod 112 to pass by, but then exert a gripping force against the fastening rod 112 after the insertion. Additionally, the rheology- modifier can provide for the building product to deform by the nail when it is being inserted, and then apply a gripping force against the nail after being inserted.

Additionally, a hole 116 formed by a nail fastening rod 112 is not damaged, and can provide sufficient compressive forces against the nail to resist the extraction therefrom. This is because the nail 112 does not damage the wall of the hole 116 during the insertion by the fibers and other materials deforming during the formation of the hole 116. Furthermore, when the fastening rod 112 is a screw, the wall of the hole 116 can have ridges and grooves that interlock with the teeth and grooves on the screw. Moreover, a substantial amount of composite material within the grooves of the screw 112 can be attached to the wall to aid in providing an increased pullout resistance. Thus, the wall of the hole 116 is sufficiently compressive so as to require the aid of a lever, screwdriver, or other extraction device to remove the nail or screw.

The cementitious building products can be used as a wood substitute for applications where multiple building products are nailed, screwed, or bolted together. It is thought, without being bound thereto, that the combination of a high weight percent and/or volume percent of fibers, as described above, provides for favorable interactions with the nails, screws, and/or bolts. This is because the high amount of fibers simulates the properties of wood. More particularly, each individual fiber can deform when first being acted upon by a nail or screw, and then compress against the nail or screw to provide a gripping force thereto. This allows for a nail or screw to be inserted within the cementitious building product without causing substantial chipping or cracking.

Additionally, the use of a high concentration of rheology-modifier can also aid in providing this functionality. As with the fibers, the rheology-modifier provides a characteristic to the cementitious building product that at least partially allows for being deformed without substantial cracking or chipping. In part, the rheology-modifier can impart a plastic-like characteristic that holds the materials together around a site that is being stressed, such as a the point where a nail or screw is being inserted. As such, the nail or screw is able to be inserted into the cementitious building product, and the rheology- modifier allows for the requisite deformation without substantial chipping or cracking. For example, the high concentration of fibers, or other filler materials can impart significant pullout resistance to the cementitious building product. The pullout resistance for a 1Od nail (e.g., nail characterized by 9 gauge or 0.128 inch in diameter and 3 inches long) imbedded one inch in a cementitious composite can range from about 30 lbf/in to about 105 lbf/in, more preferably about 40 lbf/in to about 95 lbf/in, and most preferably about 50 lbf/in to about 85 lbf/in. The pullout resistance for a more porous cementitious composite can range from about 25 lbf/in to about 90 lbf/in, more preferably about 30 lbf/in to about 70 lbf/in, and most preferably about 40 lbf/in to about 60 lbf/in. The pullout resistance for a harder cementitious composite can range from about 15 lbf/in to about 60 lbf/in, more preferably from about 18 lbf/in to about 50 lbf/in, and most preferably about 20 lbf/in to about 50 lbf/in. However, it should be understood that the pullout resistance for a product at a given density can change by altering the amount of fiber, porosity, filler, type of nail, and the like.

Similarly, the pullout resistance for a screw imbedded one inch in a cementitious composite can range from about 200 lbf/in to about 1,000 lbf/in, more preferably about 300 lbf/in to about 950 lbf/in, and most preferably about 400 lbf/in to about 900 lbf/in. However, it should be understood that the pullout resistance for a product at a given density can change by altering the amount of fiber, porosity, filler, type of nail, and the like.

Additionally, the cementitious composites primarily comprise inorganic materials they are less prone to rot when kept in a moist environment compared to wood. Even though organic fibers may have a tendency to degrade under certain conditions, the generally high alkalinity of hydraulic cement will inhibit spoilage and rotting in most circumstances.

EXAMPLES OF EMBODIMENTS OF THE INVENTION Example 1

Various extrudable compositions having different component concentrations are prepared in accordance with the present invention. All mixtures are mixed according to the normal mixing procedures described above and in the references incorporated herein. Briefly, a fibrous mixture of fiber, rheology modifying agent, and water is mixed for a mixing time of 1 hour before the additional components are added and mixed for an additional hour. The extrudable compositions are formulated as illustrated in Tables 1-6.

Table 1

SW = softwood and HW = hardwood Table 3

SW = softwood and HW = hardwood Table 6

SW = softwood and HW = hardwood

Following mixing, the compositions are extruded through a die head having a rectangular opening of about 2 inches by about 4 inches. A composite building product in the shape of a two-by-four is prepared. It is heated at a temperature of about 145°F (about 63°C) for about 2 days in order to controllably remove a portion of the water while allowing or accelerating hydration of the Portland cement by the water that is not removed. The building product is characterized by being able to be sawed using an ordinary wood saw and drilled using an ordinary wood drill bit. Nails can be hammered and screws can be screwed into the building products using conventional tools used to work with wood products of similar dimension. Example 2

Various extrudable compositions having different component concentrations are prepared in accordance with Example 1. The extrudable compositions are formulated as illustrated in Tables 7-8.

Table 7

Mix # 1 % Total Mix # 2 % Total Mix # 3 % Total

Material KG Wet KG Wet KG Wet

Softwood Fiber 6.80 11% 6.8 10% 5 10%

Hardwood Fiber - 0% 0 0% 0 0%

Inorganic Microfiber - 0% 0 0% 0 0%

Lightweight Filler - 0% 0 0% 0 0%

Conventional Filler 3.94 6% 3.94 6% 4 8%

Rheology Modifying Agent 1.00 2% 0.6 1 % 0.6 1 %

Cement 22.60 35% 22.6 34% 23 44%

Water 30.00 47% 32 49% 20 38%

Total 64.34 100% 65.94 100% 52.6 100% Table 8

Mix # 4 % Total Mix # 5 % Total Mix # 6 % Total

Material KG Wet KG Wet KG Wet

Softwood Fiber 3.4 7% 4 8% 4 8%

Hardwood Fiber 0 0% 0 0% 1 2%

Inorganic Microfiber 0 0% 3 6% 2.5 5%

Lightweight Filler 0 0% 1 2% 0 0%

Conventional Filler 3.94 8% 0 0% 0 0%

Rheology Modifying Agent 0.6 1 % 0.6 1 % 0.6 1 %

Cement 22.6 49% 23 45% 23 45%

Water 16 34% 20 39% 20 39%

Total 46.54 100% 51.6 100% 51.1 100%

The cementitious compositions exemplified by Mixes 1-6 are extruded into a building product and cured (e.g., by early heating). The amounts of each component are then calculated on a dry basis, and provided in Tables 9-10.

Table 9

Mix # 1 % Total Mix # 2 % Total Mix # 3 % Total

Material KG Dry KG Dry KG Dry

Softwood Fiber 6.80 20% 6.8 20% 5 15%

Hardwood Fiber - 0% 0 0% 0 0%

Inorganic Microfiber - 0% 0 0% 0 0%

Lightweight Filler - 0% 0 0% 0 0%

Conventional Filler 3.94 1 1 % 3.94 12% 4 12%

Rheology Modifying Agent 1.00 3% 0.6 2% 0.6 2%

Cement 22.60 66% 22.6 67% 23 71 %

Water - 0% 0 0% 0 0%

Total 34.34 100% 33.94 100% 32.6 100%

Table 10

Mix ; £ 4 % Total Mix # 5 % Total Mix # 6 % Total

Material KG Dry KG Dry KG Dry

Softwood Fiber 3.4 1 1 % 4 13% 4 13%

Hardwood Fiber 0 0% 0 0% 1 3%

Inorganic Microfiber 0 0% 3 9% 2.5 8%

Lightweight Filler 0 0% 1 3% 0 0%

Conventional Filler 3.94 13% 0 0% 0 0%

Rheology Modifying Agent 0.6 2% 0.6 2% 0.6 2%

Cement 22.6 74% 23 73% 23 74%

Water 0 0% 0 0% 0 0%

Total 30.54 100% 31.6 100% 31.1 100%

Examnle 3

The flexural strength of the extruded cementitious building products were tested and compared to wood. More particularly, the flexural strength was tested as a function of the displacement in inches in response to an applied force in pounds. As such, the displacement of the wood (x) was compared to a non-reinforced extruded composite (solid diamond - ♦), fiberglass rebar reinforced extruded building product (solid square - ■), and a steel rebar reinforced extruded building product (solid triangle - A), as depicted in Figure 8. As shown, the extruded cementitious building products mimicked the displacement of the wood up to about 275 lbs of force. Additionally, the fiberglass rebar and steel rebar reinforced extruded building products showed more displacement for the same force in comparison to the wood. Thus, extruded cementitious building products can mimic wood at lower-end forces, and the rebar reinforced cementitious building products can actually have greater displacement for a given force in comparison to wood. Example 4

The tensile strength of an embodiment of the extruded cementitious building product was tested. As such, the elongation percentage of the extruded cementitious building product was measured as a function of tensile strength in pounds per square inch (psi), which is depicted in Figure 9. The results of the study indicate that extruded cementitious building product is capable of elongating up to about 1.45% before yielding to the tensile force at about 500 psi. Example 5

For comparative purposes, the displacement of wood in response to a compressive pressure was measured and compared to the displacement of an embodiment of the extruded cementitious building product. The wood (solid diamond - ♦) and extruded cementitious building product (solid square - ■) were each tested in the form of a I"x3" (1 inch by 3 inches) article, with the force being applied with the grain at the end surface of each beam. The results of the study are presented in Figure 10. The wood exhibited a gradual increase in displacement at the lower pressures, but then displaced from about 10% displacement to about 50% displacement at about 4,400 psi, which is shown by the nearly horizontal line. The extruded cementitious building product exhibited a similar displacement trend at a lower compressive load of about 1,500 to about 2,000 psi, but began to resist displacement after only being displaced about 30%. Thus, when a force is applied to the wood or extruded cementitious building product at the end surface, a large displacement can occur at a critical force before again resisting the compressive force. Example 6

A cementitious composition (6-7-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 1 IA. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C in order to controllably remove a portion of the water while accelerating hydration of the cement binder. The cured extrudate was thereafter substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.91 cm; width of 8.64 cm; height of 1.92 cm; and weight of 232.45 g. The building product exhibited the properties described in Table 1 IB.

Table HA

Mass Percent of Volume Percent

Mass Input Total of Total

Com osition k Com osition Com osition

Delvo: concrete stabilizer sold by BASF

Table HB

Example 7

A cementitious composition (6-8-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 12 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.4 cm; width of 8.8 cm; height of 1.96 cm; and weight of 256.49 g. The building product exhibited the properties described in Table 12B. 60455

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Table 12A

Mass Percent of Volume Percent Mass Input Total of Total

Material k Com osition Co osition

Table 12B

Example 8

A cementitious composition (6-14-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 13 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.53 cm; width of 8.77 cm; height of 1.96 cm; and weight of 228.08 g. The building product exhibited the properties described in Table 13B.

Table 13A

Wet Mass Percent Wet Volume Mass Input of Total Percent of Total

Material k Co os tion Com osition

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Table 13B

Example 9

A cementitious composition (6-14-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 14 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.57 cm; width of 8.96 cm; height of 2.06 cm; and weight of 242.88 g. The building product exhibited the properties described in Table 14B.

Table 14A

Wet Mass Percent Wet Volume

Mass Input of Total Percent of Total

Material (kqj Com osition Composition

Table 14B

Example 10

A cementitious composition (6-21-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 15 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product exhibited the properties described in Table 15B.

Table 15A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) (%) vol %

Table 15B

Example 11

A cementitious composition (6-27-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 16 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.93 cm; width of 8.86 cm; height of 4.33 cm; and weight of 550.03 g. The building product exhibited the properties described in Table 16B. Table 16A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 16B

Example 12

A cementitious composition (6-29-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 17 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.64 cm; width of 8.87 cm; height of 2.03 cm; and weight of 200.67 g. The building product exhibited the properties described in Table 17B.

Table 17A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) % VOl %

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Table 17B

Example 13

A cementitious composition (7-3-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 1 SA. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.4 cm; width of 8.4 cm; height of 1.86 cm; and weight of 197.580 g. The building product exhibited the properties described in Table 18B.

Table 18A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table ISB

Example 14

A cementitious composition (7-5-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 19 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 12.62 cm; width of 8.8 cm; height of 1.92 cm; and weight of 313.34 g. The building product exhibited the properties described in Table 19B.

Table 19A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 19B

Example 15

A cementitious composition (7-7-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 2OA. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the 2006/060455

-52- following dimensions: length of 35.3 cm; width of 8.8 cm; height of 1.8 cm; and weight of 852.12 g. The building product exhibited the properties described in Table 2OB.

Table 2OA

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) k % vol %

Table 2OB

Example 16

A cementitious composition (7-13-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 21 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product exhibited the properties described in Table 2 IB.

Table 21A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) k (%) vol %

Table 21B

Example 17

A cementitious composition (7-13-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 22A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product exhibited the properties described in Table 22B.

Table 122A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) (%) vol(%)

Table 22B

Example 18 A cementitious composition (7-14-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 23 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product exhibited the properties described in Table 23B.

Table 23A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 23B

Example 19

A cementitious composition (7-14-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 24A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 15.2 cm; width of 8.5 cm; height of 1.8 cm; and weight of 211.82 g. The building product exhibited the properties described in Table 24B. Table 24A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 24B

Example 20

A cementitious composition (7-14-06-3) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 25 A. The extrudate was covered in plastic and stored at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely dehydrated in a drying oven, and the building product was tested dry. The building product had the following dimensions: length of 15.4 cm; width of 8.4 cm; height of 1.8 cm; and weight of 212.15 g. The building product exhibited the properties described in Table 25B.

Table 25A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

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Table 25B

Example 21

A cementitious composition (7-17-06-1-0) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 26A. The extrudate was immediately placed in a drying oven after extrusion. After complete dehydration, the extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.6 cm; width of 8.8 cm; height of 1.95 cm; and weight of 261.57 g. The building product exhibited the properties described in Table 26B.

Table 26A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent (kg) (%) vol %

Table 26B

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Example 22

A cenientitious composition (7-17-06-1-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 27 A. The extrudate was placed in a drying oven 1 hour after extrusion. After complete dehydration, the extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.6 cm; width of 8.8 cm; height of 1.95 cm; and weight of 261.57 g. The building product exhibited the properties described in Table 27B.

Table 27A

Wet Mass Percent Wet Volume of Total Percent of Total

Table 27B

Example 23

A cementitious composition (7-17-06-1-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding T7US2006/060455

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Table 28A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition component) kg (%) vol(%)

Table 28B

Example 24

A cementitious composition (7-17-06-1-3) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 29 A. The extrudate was placed in a drying oven 3 hours after extrusion. After complete dehydration, the extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 14.3 cm; width of 8.7 cm; height of 1.94 cm; and weight of 238.98 g. The building product exhibited the properties described in Table 29B. 2006/060455

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Table 29A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k (%) vol %

Table 29B

Example 25

A cementitious composition (7-17-06-1-4) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 30A. The extrudate was placed in a drying oven 4 hours after extrusion. After complete dehydration, the extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 15.2 cm; width of 8.7 cm; height of 1.96 cm; and weight of 245.57 g. The building product exhibited the properties described in Table 30B.

Table 3OA

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

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Table 3OB

Example 26

A cementitious composition (7-17-06-1-5) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 3 IA. The extrudate was placed in a drying oven 5 hours after extrusion. After complete dehydration, the extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 15.2 cm; width of 8.7 cm; height of 1.93 cm; and weight of 250.77 g. The building product exhibited the properties described in Table 3 IB.

Table 31A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 31B

Example 27

A cetnentitious composition (7-17-06-1-6) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 32A. The extrudate was placed in a drying oven 6 hours after extrusion. After complete dehydration, the extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 15.8 cm; width of 8.7 cm; height of 1.96 cm; and weight of 250.77 g. The building product exhibited the properties described in Table 32B.

Table 32A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (Kg) (%) vol(%)

Table 32B

Example 28

A cementitious composition (7-17-06-1-28) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 33A. The extrudate was covered in plastic and maintained at room temperature. The extrudate was then placed in a drying oven 28 days hours after extrusion. After complete dehydration, the extrudate was covered in plastic and maintained at room temperature. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated the day before testing, and the building product was tested dry. The building product exhibited the properties described in Table 33B.

Table 33A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k %

Table 33B

Example 29

A cementitious composition (7-17-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 34A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 35.7 cm; width of 8.9 cm; height of 1.9 cm; and weight of 547.09 g. The building product exhibited the properties described in Table 34B. Table 34A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent (k %

Table 34B

Example 30

A cementitious composition (7-18-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 35 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 35.72 cm; width of 8.7 cm; height of 2 cm; and weight of 580.88 g. The building product exhibited the properties described in Table 35B.

Table 35A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent (kg) (%) vol %

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Total Wei ht (kg): 61.575 100.0% 100.0%

Example 31

A cementitious composition (7-20-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 36A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 35.4 cm; width of 8.9 cm; height of 1.9 cm; and weight of 560.28 g. The building product exhibited the properties described in Table 36B.

Table 36A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 36B

Example 32

A cementitious composition (7-21-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 37A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 35.1 cm; width of 8.9 cm; height of 2.0 cm; and weight of 817.17 g. The building product exhibited the properties described in Table 37B.

Table 37A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent (kg) (%) vol %

Table 37B

Example 33

A cementitious composition (7-21-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 38 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 29 cm; width of 8.8 cm; height of 2.0 cm; and weight of 451.38 g. The building product exhibited the properties described in Table 38B.

Table 38A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 38B

Example 34

A cementitious composition (7-24-06-1) was prepared and processed into a cenientitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 39A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19 cm; width of 8.3 cm; height of 1.9 cm; and weight of 264.14 g. The building product exhibited the properties described in Table 39B.

Table 39A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) (%) vol(%)

Water 29.000 48.1 68.0

Table 39B

Example 35

A cementitious composition (7-24-06-1-0) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 4OA. The extrudate was covered in plastic at room temperature, and then placed in drying oven on same day as extrusion. The dried extrudate was then placed plastic and stored at room temperature. The extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19.5 cm; width of 9 cm; and height of 2 cm. The building product exhibited the properties described in Table 4OB.

Table 4OA

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 4OB

T7US2006/060455

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Example 36

A cementitious composition (7-24-06-1-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 41 A. The extrudate was covered in plastic at room temperature, and then placed in drying oven one day after extrusion. The dried extrudate was then placed plastic and stored at room temperature. The extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19.5 cm; width of 9 cm; and height of 2 cm. The building product exhibited the properties described in Table 41B.

Table 41A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) (%) vol %

Table 41B

Example 37

A cementitious composition (7-24-06-1-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 42A. The extrudate was covered in plastic at room temperature, and then placed in drying oven two days after extrusion. The dried extrudate was then placed plastic and stored at room temperature. The extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19.5 cm; width of 9 cm; and height of 2 cm. The building product exhibited the properties described in Table 42B.

Table 42A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 42B

Example 38

A cementitious composition (7-24-06-1-4) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 43A. The extrudate was covered in plastic at room temperature, and then placed in drying oven four days after extrusion. The dried extrudate was then placed plastic and stored at room temperature. The extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19.5 cm; width of 9 cm; and height of 2 cm. The building product exhibited the properties described in Table 43B. Table 43A Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k (%)

Table 43B

Example 39

A cementitious composition (7-24-06-1-8) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 44A. The extrudate was covered in plastic at room temperature, and then placed in drying oven eight days after extrusion. The dried extrudate was then placed plastic and stored at room temperature. The extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19.5 cm; width of 9 cm; and height of 2 cm. The building product exhibited the properties described in Table 44B.

Table 44A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent (kg) (%)

6 060455

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Table 44B

Example 40

A cementitious composition (7-24-06-1-22) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 45A. The extrudate was covered in plastic at room temperature, and then placed in drying oven twenty-two days after extrusion. The dried extrudate was then placed plastic and stored at room temperature. The extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19.5 cm; width of 9 cm; and height of 2 cm. The building product exhibited the properties described in Table 45B.

Table 45A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) (%) voirn

Table 45B

Example 41

A cementitious composition (7-24-06-1-32) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 46A. The extrudate was covered in plastic at room temperature, and then placed in drying oven thirty-two days after extrusion. The dried extrudate was then placed plastic and stored at room temperature. The extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 19.5 cm; width of 9 cm; and height of 2 cm. The building product exhibited the properties described in Table 46B.

Table 46A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) kg) (%) vol(%)

Table 46B

Example 42

A cementitious composition (7-24-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 47 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The 6 060455

-73- building product had the following dimensions: length of 17.4 cm; width of 8.5 cm; and height of 1.9 cm. The building product exhibited the properties described in Table 47B.

Table 47A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 47B

Example 43

A cementitious composition (7-24-06-3) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 48A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 17.9 cm; width of 8.4 cm; height of 1.9 cm; and a weight of 232.8 g. The building product exhibited the properties described in Table 48B.

Table 48A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k (%) vol(%)

Table 48B

Example 44

A cementitious composition (7-31-06-7) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 49 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.6 cm; width of 8.4 cm; height of 1.95 cm; and a weight of 199.64 g. The building product exhibited the properties described in Table 49B.

Table 49A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) k % vol %

Table 49B

6 060455

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Example 45

A cementitious composition (7-31-06-8) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 50A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.6 cm; width of 8.4 cm; height of 1.95 cm; and a weight of 199.64 g. The building product exhibited the properties described in Table 5OB.

Table 5OA

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) (%) vol %

Table 5OB

Example 46

A cementitious composition (8-1-06-4) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 5 IA. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.13 cm; width of 8.4 cm; height of 1.96 cm; and a weight of 204.17 g. The building product exhibited the properties described in Table 5 IB.

Table 51A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 51B

Example 47 '

A cementitious composition (8-1-06-9) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 52A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 17.04 cm; width of 8.58 cm; height of 1.99 cm; and a weight of 255.36 g. The building product exhibited the properties described in Table 52B. Table 52A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

Table 52B

Example 4S

A cementitious composition (8-2-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 53A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.34 cm; width oil.66 cm; height of 1.86 cm; and a weight of 215.51 g. The building product exhibited the properties described in Table 53B.

Table 53A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (k % vol %

Table 53B

Example 49

A cementitious composition (8-2-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 54A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.1 cm; width of 7.87 cm; height of 1.87 cm; and a weight of 226.8 g. The building product exhibited the properties described in Table 54B.

Table 54A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) k (%) vol %

Table 54B

Example 50

A cementitious composition (8-2-06-3) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 55 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 35 cm; width of 8.81 cm; height of 1.98 cm; and a weight of 660.44 g. The building product exhibited the properties described in Table 55B.

Table 55A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent (kg) (%) vol(%)

Table 55B

Example 51

A cementitious composition (8-2-06-5) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 56 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 15.4 cm; width of 8.35 cm; height 6 060455

-80- of 2.04 cm; and a weight of 197.18 g. The building product exhibited the properties described in Table 56B.

Table 56A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k (%) vol %

Table 56B

Example 52

A cementitious composition (8-2-06-6) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 57A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 17.1 cm; width of 8.62 cm; height of 2.03 cm; and a weight of 248.32 g. The building product exhibited the properties described in Table 57B. 6 060455

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Table 57A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k vol %

Table 57B

Example 53

A cementitious composition (8-16-06-1) was prepared and processed into a cenientitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 58A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 15.83 cm; width of 6.9 cm; height of 0.99 cm; and a weight of 128.6 g. The building product exhibited the properties described in Table 58B. 06/060455

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Table 58A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 58B

Example 54

A cementitious composition (9-6-06-1-5) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 59A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 5 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.7 cm; width of 8.97 cm; height of 2.03 cm; and a weight of 312.42 g. The building product exhibited the properties described in Table 59B.

Table 59A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol(%

Table 59B

Example 55

A cementitious composition (9-6-06-1-6) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 6OA. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 6 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 15.9 cm; width of 8.91 cm; height of 2.03 cm; and a weight of 296.28 g. The building product exhibited the properties described in Table 6OB.

Table 6OA

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 6OB

Example 56

A cementitious composition (9-6-06-1-7) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 6 IA. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 7 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 1 1.1 cm; width of 8.91 cm; height of 2.05 cm; and a weight of 211.26 g. The building product exhibited the properties described in Table 6 IB.

Table 61A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 61B

Example 57

A cementitious composition (9-6-06-1-8) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 62 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 16.6 cm; width of 8.63 cm; height of 1.95 cm; and a weight of 199.64 g. The building product exhibited the properties described in Table 62B. Table 62A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 62B

Example 58

A cementitious composition (9-8-06-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 63A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 10.95 cm; width of 8.65 cm; height of 1.87 cm; and a weight of 189.67 g. The building product exhibited the properties described in Table 63B.

Table 63A

Wet Mass Percent Wet Volume of Total Percent of Total

Table 63B

Example 59

A cementitious composition (9-8-06-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 64A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55⁰C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product had the following dimensions: length of 11.7 cm; width of 8.6 cm; height of 1.9 cm; and a weight of 202.8 g. The building product exhibited the properties described in Table 64B.

Table 64A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 64B

Example 60

A cementitious composition (9-18-06-1-1) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 65A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was removed from the curing tank and tested wet. The wet building product had the following dimensions: length of 12 cm; width of 9 cm; height of 2 cm; and a weight of 308.57 g. Additionally, the building product was dried to have the following dry properties: length of 10.63 cm; width of 8.54 cm; height of 1.8 cm; and weight of 179.3 g. The building product exhibited the properties described in Table 65B.

Table 65A

Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition com onent k % vol %

Table 65B

Example 61

A cementitious composition (9-18-06-1-2) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 66A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product exhibited the properties described in Table 66B.

Table 66A Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

(component) (kg) % vol %

Table 66B

Example 62

A cementitious composition (9-18-06-1-3) was prepared and processed into a cementitious building product, and the building product was tested to determine physical properties. Briefly, the cementitious building product was prepared by mixing and extruding the composition described in Table 67 A. The extrudate was covered in plastic at room temperature until set. The set extrudate was then placed in a curing tank for 8 days and maintained at 55°C. The cured extrudate was substantially completely again dehydrated in a drying oven until completely dehydrated, and the building product was tested dry. The building product exhibited the properties described in Table 67B. Table 67 A Wet Mass Percent Wet Volume of Total Percent of Total

Material Mass Input Composition Composition

Table 67B

Example 63 The cementitious building product of Example 6 was tested to determine the nail hold strength according to standard ASTM methods described in Designation: D 1761 — 88 (Reapproved 2000), published by ASTM. The cementitious building product was determined to have a nail hold strength of 72.24 lbf/in. Example 64 The cementitious building product of Example 9 was tested to determine the nail hold strength and screw hold strength according to standard ASTM methods described in Designation: D 1761 - 88 (Reapproved 2000), published by ASTM. The cementitious building product was determined to have a nail hold strength of 86.9 lbf/in, and a screw hold strength of 862.16 lbf/in. Example 65

The cementitious building product of Example 10 was tested to determine the nail hold strength and screw hold strength according to standard ASTM methods. The cementitious building product was determined to have a nail hold strength of 35.86 lbf/in, and a screw hold strength of 399.39 lbf/in. The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

What is claimed is:

Claims

1. A cementitious composite product for use as a lumber substitute, the product comprising: a cured cementitious composite comprised of a hydraulic cement, a rheology- modifying agent, and fibers substantially homogeneously distributed through the cured cementitious composition and included in an amount greater than about 10% by weight of the cured cementitious composite, said cured cementitious composite characterized by: a cross sectional thickness of at least 2 mm; a flexural stiffness in a range of about 200,000 psi to about 5,000,000 psi; accepting standard wood nails using a hammer or nail gun and standard wood screws using a screw driver; a nail pullout resistance of at least about 25 lbf/in using standard ASTM method; and a screw pullout strength of at least about 300 lbf/in using standard ASTM method; said cured cementitious composition being prepared by a process comprising: mixing together water, fibers and a rheology-modifying agent to form a fibrous mixture in which the fibers are substantially homogeneously dispersed; adding hydraulic cement to the fibrous mixture to yield an extrudable cementitious composition having a plastic consistency and which includes water at a concentration from about 25% to about 75% by wet weight, hydraulic cement at a concentration from about 25% to about 75% by wet weight, rheology-modifying agent at a concentration from about 0.1% to about 10% by wet weight, and fibers at a concentration greater than about 8% by wet weight; extruding the extrudable cementitious composition into a green intermediate extrudate having a predefined cross-sectional area, the green extrudate being form-stable upon extrusion and capable of retaining substantially the cross-sectional area so as to permit handling without breakage; causing or allowing the hydraulic cement to cure to form the cementitious composite in a manner so that the hydraulic cement contributes a binding strength that is at least about 50% of the overall binding strength of the cementitious composite.

2. A cementitious composite product as in claim 1, wherein the hydraulic cement is cured by heating the intermediate extrudate to remove a portion of the water by evaporation and reduce the density of the extrudate.

3. A cementitious composite product as in claim 1, wherein the extrudable composition has a nominal water/cement ratio greater than about 0.75 prior to heating and an actual water/cement ratio less than about 0.5 after evaporation of the portion of water.

4. A cementitious composite product as in claim 1, further comprising at least one reinforcing member selected from the group consisting of rebar, wire, mesh, and fabric at least partially encapsulated by the cementitious composite.

5. A cementitious composite product as in claim 4, wherein the least one reinforcing member is bonded to the cementitious composite by a bonding agent.

6. A cementitious composite product as in claim 1, wherein the fibers are included in an amount greater than about 15% by dry weight of the cementitious composite.

7. A cementitious composite product as in claim 1, wherein the fibers are included in an amount greater than about 20% by dry weight of the cementitious composite.

8. A cementitious composite product as in claim 1, the cementitious composite being configured into a trim board.

9. A cementitious composite product as in claim 1, the cementitious composite comprising a building product that is a substitute for a lumber building product.

'

10. A cementitious composite product as in claim 1, wherein the cementitious composite has a density less than about 1.2 g/cm³.

11. A cementitious composite product as in claim 1, wherein the cementitious composite is sawable using a standard wood saw.

12. A cementitious composite product as in claim 9, wherein the building product is in a shape selected from the group consisting of a rod, bar, pipe, cylinder, board, I-beams, utility pole, trim board, two-by-four, structural board, one-by-eight, panel, flat sheet, roofing tile, and a board having a hollow interior.

13. A cementitious composite product as in claim 9, wherein the building product is capable of receiving a 1Od nail by being hammered therein with a hand hammer without significant bending.

14. A cementitious composite product as in claim 9, wherein the building product has a nail pullout resistance of at least about 50 lbf/in for a 1Od nail.

15. A cementitious composite product as in claim 9, wherein the building product has a screw pullout resistance of at least about 500 lbf/in.

16. A cementitious composite product as in claim 1, characterized by at least one of the following: the fibers being selected from the group consisting of hemp fibers, cotton fibers, plant leaf or stem fibers, hardwood fibers, softwood fibers, glass fibers, graphite fibers, silica fibers, ceramic fibers, metal fibers, polymer fibers, polypropylene fibers, carbon fibers, and combinations thereof; the hydraulic cement being selected from the group consisting of Portland cements, MDF cements, DSP cements, Densit-type cements, Pyrament-type cements, calcium aluminate cements, plasters, silicate cements, gypsum cements, phosphate cements, high alumina cements, micro fine cements, slag cements, magnesium oxychloride cements and combinations thereof; the rheology modifying agent being selected from the group consisting of polysaccharides, proteins, celluloses, starches, methylhydroxyethylcellulose, hydroxymethylethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, amylpectin, amulose, seagel, starch acetates, starch hydroxyethers, ionic starches, long chain alkyl- starches, dextrins, amine starches, phosphate starches, dialdehyde starches, clay, and combinations thereof; including a set accelerator selected from the group consisting of Na2UH, KCO3, KOH, TSTaOH, CaCk, CO2, magnesium chloride, triethanolamine, aluminates, inorganic salts HCl, inorganic salts HNO3, inorganic salts H₂SO₄, calcium silicate hydrates (C-S-H), and combinations thereof; or including a filler material selected from the group consisting of sand, dolomite, gravel, rock, basalt, granite, limestone, sandstone, glass beads, aerogels, xerogels, seagel, mica, clay, synthetic clay, alumina, silica, fly ash, silica fume, tabular alumina, kaolin, glass microspheres, ceramic spheres, gypsum dihydrate, calcium carbonate, calcium aluminate, and combinations thereof

17. A method of manufacturing a cementitious composite having properties suitable for use as a substitute for wood lumber, comprising: mixing together water, fibers and a rheology-modifying agent to form a fibrous mixture in which the fibers are substantially homogeneously dispersed; adding hydraulic cement to the fibrous mixture to yield an extrudable cementitious composition having a plastic consistency and which includes water at a concentration from about 25% to about 75% by wet weight, hydraulic cement at a concentration from about 25% to about 75% by wet weight, rheology-modifying agent at a concentration from about 0.1% to about 10% by wet weight, and fibers at a concentration greater than about 5% by wet weight; extruding the extrudable cementitious composition into a green intermediate extrudate having a predefined cross-sectional area, the green extrudate being form- stable upon extrusion and capable of retaining substantially the cross-sectional area so as to permit handling without breakage; causing or allowing the hydraulic cement to cure to form the cementitious composite in a manner so that the hydraulic cement contributes a binding strength that is at least about 50% of the overall binding strength of the cementitious composite, which is characterized by one or more of the following: a cross sectional thickness of at least 2 mm; a density of less than about 1.2 g/cm³; a flexural stiffness in a range of about 200,000 psi to about 5,000,000 psi; accepting standard wood nails using a hammer or nail gun and standard wood screws using a screw driver; a nail pullout resistance of at least about 25 lbf/in using standard ASTM method; a screw pullout resistance of at least about 300 lbf/in using standard ASTM method; or being sawable using a standard wood saw,

18. A method as in claim 17, wherein the fibers are included in an amount greater than about 10% by wet weight of the extrudable cementitious composition.

19. A method as in claim 17, wherein the fibers are included in an amount greater than about 15% by wet weight of the extrudable cementitious composition.

20. A method as in claim 17, wherein the hydraulic cement is cured by heating the intermediate extrudate to remove a portion of the water by evaporation and reduce the density of the extrudate.

21. A method as in claim 20, wherein the extrudable composition has a nominal water/cement ratio greater than about 0.75 prior to heating and an actual water/cement ratio less than about 0.5 after evaporation of the portion of water.

22. A method as in claim 17, further comprising extruding the extrudable cementitious composition around at least one reinforcing member selected from the group consisting of rebar, wire, mesh, and fabric so as to at least partially encapsulate the reinforcing member within the green extrudate.

23. A method as in claim 22, further comprising: extruding a green extrudate having at least one continuous hole that is form- stable; inserting a rebar and a bonding agent into the continuous hole while the cementitious composite is in a form-stable green state or is at least partially cured; and bonding the rebar to a surface of the continuous hole with the bonding agent, optionally by applying the bonding agent to the rebar before inserting the rebar.

24. A method as in claim 17, further comprising configuring the cementitious composite into trim board.

25. A method as in claim 17, further comprising processing the cementitious composite into a building product so as to be a substitute for a lumber building product having a shape selected from the group consisting of a rod, bar, pipe, cylinder, board, I- beams, utility pole, trim board, two-by-four, structural board, one-by-eight, panel, flat sheet, roofing tile, and a board having a hollow interior.

26. A method as in claim 17, further comprising processing the form-stable green extrudate and/or cured cementitious composite by at least one process selected from the group consisting of bending, cutting, sawing, sanding, milling, texturizing, planing, polishing, buffing, pre-drilling holes, painting, and staining.

27. A method as in claim 17, further comprising recycling a portion of a scrap green extrudate obtained from the processing the green extrudate, wherein the recycling includes combining the scrap green extrudate with the extrudable cementitious composition.

28. A method as in claim 17, wherein the cementitious composition is extruded through a die opening and/or by means of roller-extrusion.

29. A method as in claim 17, further comprising die stamping or impact molding the green intermediate extrudate.