WO1993010972A1 - Composites legers - Google Patents

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Publication number
WO1993010972A1
WO1993010972A1 PCT/US1992/010276 US9210276W WO9310972A1 WO 1993010972 A1 WO1993010972 A1 WO 1993010972A1 US 9210276 W US9210276 W US 9210276W WO 9310972 A1 WO9310972 A1 WO 9310972A1
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WO
WIPO (PCT)
Prior art keywords
composite
cement
density
foam
phase
Prior art date
Application number
PCT/US1992/010276
Other languages
English (en)
Inventor
Timothy D. Tonyan
Lorna J. Gibson
Original Assignee
Massachusetts Institute Of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Massachusetts Institute Of Technology filed Critical Massachusetts Institute Of Technology
Publication of WO1993010972A1 publication Critical patent/WO1993010972A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/08—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding porous substances
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/0016—Granular materials, e.g. microballoons
    • C04B20/002—Hollow or porous granular materials
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04—Portland cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • the invention relates to lightweight composites for structural applications, particularly low density cellular composites characterized by cell walls with a sandwich beam microstructure.
  • Prefabricated structural panels often include a lightweight core.
  • such panels are constructed as sandwich panels including a foam core.
  • Conventional cement foam materials with densities less than 20 pounds per cubic foot do not have sufficient strength and ductility to be building panel cores.
  • Sandwich panels having a low density polymer foam core, while lightweight, have performance limitations as structural members such as roof or wall panels because of stiffness constraints.
  • creep of the polymer foam core limits panel performance and economy.
  • panel spans are limited to 10 feet or less due to concerns over creep and the resulting increase in panel deflection over time. In warm regions, concern that a roof may become sufficiently warm to cause a decrease in foam stiffness limits the widespread application of foam core structural panels.
  • Core combustibility in polymer foam core panels also requires that they be covered with a layer of fire resistive material such as gypsum board, before they can be used as structural components.
  • foundations are typically made in one of two ways. For houses with basements, foundations are made from poured-in-place concrete. Houses with crawl spaces or shallow foundations often use concrete masonry units (CMU's) for the vertical elements in addition to cast-in- place footings. Both cast-in-place concrete and CMU construction are labor intensive and highly sensitive to weather conditions. Neither provide a basement or foundation that is well insulated, and an additional layer of polymer foam insulation must typically be applied to the exterior face of the foundation wall to provide adequate thermal insulation.
  • CMU's concrete masonry units
  • a low density composite including at least two aggregate phase particles, further includes three phases, the aggregate particles, a high density phase associated with the aggregate particles which surrounds low overall density aggregate particles or is the outer wall or shell of hollow aggregate particles, and a low density matrix phase which occupies the interstitial space between the aggregate particles to produce a sandwich beam microstructure.
  • the low density matrix phase can be cellular concrete or foam.
  • Aggregate particles are characterized by an overall low density and can be an organic material such as pre- expanded polystyrene, recycled reground plastic foam, and hollow polymeric spheres or cubes; an inorganic material such as hollow glass spheres composed of silicate and borosilicate glass and thin-walled hollow or low density cellular ceramic or steel spheres or cubes.
  • Aggregate phase particles can be selected to have a particular geometry and can have cubic, spherical or other regular geometries.
  • the high density phase can include cement as well as fiber and other additives such as silica fume, sand, cement paste and superplasticizers.
  • Superplasticizers are additives which reduce the amount of water needed for mixing with the cement and other additives.
  • the high density phase is further characterized by a high stiffness and a density in the range of from about 85 to about 115 pounds per cubic foot and is selected so that it has a density and stiffness, i.e., Young's Modulus, at least five times greater than the density and stiffness of the matrix low density phase.
  • the aggregate particle density which can be in the range of from about 1 to about 10 pounds per cubic foot, is selected so that it is at most one-sixth that of the low density matrix phase, which is characterized by a density in the range of from about 0.5 to about 30 pounds per cubic foot.
  • the cellular matrix density is typically in a range of from about 15 to about 30 pounds per cubic foot.
  • Polymer foams can have densities of less than 1 pound per cubic foot.
  • the lightweight composite further includes a first aggregate particle and a second aggregate particle each of which is covered with or has a wall of the high density phase.
  • the particles are separated by the matrix phase which occupies the interstitial space between the aggregate phase particles to create the desired .andwich beam microstructure.
  • the thickness of the high density phase coating or wall is in the range of from about 20 icrons to about 100 microns and the thickness of the low density matrix phase occupying the interstitial space between the aggregate phase particles is typically in a range of from about 100 microns to about 500 microns.
  • a lightweight cement composite includes lightweight aggregate particles dispersed in a matrix phase of cellular concrete.
  • the lightweight cement composite can further include fiber, present in a concentration in a range of from about 0.3% to about 1.0% by weight of cement, which can be polymer fiber such as polyester and polypropylene fiber; inorganic fiber such as glass fiber, including silicate and borosilicate fiber, E-glass and other glass fiber coated with alkali resistant coatings.
  • the fiber can have a strand-like geometry and be in a range of from about 0.25 to about 1.5 inches long.
  • the lightweight aggregate particles can be present in the composite in a quantity in the range of from about 40 to about 55% volume fraction of the composite.
  • the lightweight aggregate particles can have a density in the range of from about 1 to about 10 pounds per cubic foot and consist of particles including a hollow or cellular lightweight interior surrounded by a shell consisting of the high, density phase material.
  • the aggregate phase material which makes up the particle wall or shell has a density and stiffness at least ive times that of the low density matrix phase and is 20-100 ⁇ thick.
  • the lightweight aggregate phase particles can have spherical, cubic or other regular geometries and range in size from about 0.5mm in diameter to about 6mm in diameter, or other relevant dimension depending on particle geometry.
  • the aggregate phase particles can be characterized by a size distribution in the range of from about 3.0 to about 6.0mm based on a relevant particle dimension.
  • the lightweight aggregate particles can be polymer particles such as expanded polystyrene foam, recycled reground plastic foam and hollow polymeric spheres, cubes and other regular shapes; inorganic particles such as hollow glass spheres made from silicate or borosilicate glass and hollow or low density cellular ceramic or steel spheres, cubes or other regular shapes with thin exterior walls.
  • the lightweight aggregate particles are coated with a high density phase material.
  • the low density, matrix phase can be a cellular concrete including a cement into which a preformed foam, which exhibits chemical compatibility with the cement, has been introduced.
  • the cement can be a high early strength cement such as Portland Type III, Normal Type I Portland cement or any type of cement compatible with the preformed foam.
  • the preformed foam can be one of several types of foaming agent suitable for the making of preformed foam cements including: saponified wood resin stabilized with animal glue; sodium compounds of aliphatic and aromatic sulfates, such as sodium lauryl, cetyl, and oleyl sulfates; sodium naphthalene isopropyl sulfate; sulfates of petroleum derivatives; complex organic compounds including keratin compounds and saponin; and inorganic compounds stabilized with organics.
  • the foam can also be produced in situ.
  • the composite can further include other additives such as silica fume, superplasticizers, sand, and polymer additives such as epoxy and latex.
  • the high density phase covered aggregate or thin walled aggregate particles and interstitial cellular concrete low density matrix material form a sandwich beam microstructure within the composite.
  • this sandwich beam microstructure results in mechanical properties for the composite which make it suitable for use as a core material for a load- bearing structural panel.
  • the material is characterized by a compressive strength in a range of from about 40psi to about 60psi, a Young's modulus in the range of from about 18,00Opsi to about 25,000psi and a modulus of rupture in the range of from about 35psi to about 55psi.
  • Another aspect of this invention provides a method for making a lightweight composite including steps of forming a slurry including a cement and water, adding lightweight aggregate to the slurry and mixing to form a thoroughly intermixed intermediate mixture of the lightweight aggregate particles and slurry, introducing a foaming agent into this thoroughly mixed intermediate mixture to produce a foamed mixture, molding the foamed mixture into a desired shaped article and finally curing the shaped article to form the composite.
  • the slurry can further include fiber and other additives including silica fume, a superplasticizer, sand and polymer additives such as epoxy and latex.
  • fiber and other additives including silica fume, a superplasticizer, sand and polymer additives such as epoxy and latex.
  • the constituents of the slurry can be mixed together in stages including dry-mixing the cement and fiber.
  • Additives such as silica fume can be dry-mixed with the cement and fiber or they can be pre ixed with water and then combined with the dry-mixed cement and fiber. Water can be added to the dry mixed cement, fiber and other additives to form a slurry.
  • the lightweight aggregate particles are thoroughly intermixed with the slurry so that the lightweight aggregate particles become coated with the cement slurry which hardens to form the high density phase.
  • the foaming agent is thoroughly intermixed with the slurry and slurry-coated lightweight aggregate particles while care is taken to preserve the foam bubbles.
  • a shaped article can be molded from the already described mixture and cured in an atmosphere having greater than 75% relative humidity at room temperature.
  • a structural panel including a first facing layer, an inner low density matrix composite layer characterized by a sandwich beam microstructure, a means for bonding the first facing layer to a first side of the inner low density matrix composite layer, a second facing layer and a means for bonding the second facing layer to a second side of the inner low density matrix composite layer.
  • the inner low density matrix composite layer can include lightweight aggregate particles dispersed in a matrix of cellular concrete.
  • the inner low density layer can be bonded to the first and second facing layers which can be structural materials such as cement, steel, wood, plywood, oriented strand board, waferboard and fiber reinforced cement boards, and non-structural materials, such as gypsum wallboard, depending upon the end use of the structural panel.
  • the means for bonding can include adhesives, such as epoxy, silicone or latex; cement hydration when bonding a cement face to a cement core and mechanical fasteners.
  • the relative thicknesses of the first facing layer, second facing layer and low density matrix composite layer can be adjusted. Both the first and second facing layers are of equal thickness, a thickness less than the low density matrix composite layer core thickness.
  • the low density matrix composite layer core is from about 4 to about 12 times thicker than a facing layer.
  • the low density matrix composite layer core is from about 8 to about 16 times the thickness of a facing layer.
  • the low density matrix composite layer core is about 8 to about 16 times the thickness of a facing layer.
  • mechanical fasteners and/or grouted joints can be provided for fastening one structural panel to another structural panel.
  • An object of this invention is to provide a low density matrix composite including at least two aggregate particles, a high density phase which surrounds said aggregate particles or forms the exterior walls of the particles and a low density matrix phase occupying the interstitial space between said aggregate particles to produce a sandwich beam microstructure.
  • Another object of this invention is to provide a lightweight cement composite comprising lightweight aggregate particles dispersed in a matrix phase of cellular concrete.
  • Another object of the present invention is the provision of a method for making a lightweight composite. Yet another object of the invention is to provide structural panels including a low density matrix composite layer.
  • FIG. 1 is a schematic illustration of a low density foam matrix phase/lightweight aggregate particle * composite microstructure.
  • FIG. 2 is a schematic expanded view of a low density matrix phase occupying interstitial space between two lightweight aggregate particles.
  • FIG. 3 is a scanning electron microscope (SEM) micrograph of a cement foam composite of the invention.
  • FIG. 4 is a scanning electron microscope (SEM) micrograph showing a cement foam cell wall between two expanded polystyrene sphere lightweight aggregate particles in a composite of the invention.
  • FIG. 5 is a scanning electron microscope (SEM) micrograph showing a high density cement phase coating around an expanded polystyrene sphere lightweight aggregate particle.
  • FIG. 6 is a scanning electron microscope (SEM) micrograph also showing a high density phase cement coating surrounding an expanded polystyrene sphere lightweight aggregate particle.
  • FIG. 7 is a graph showing compressive strength of lightweight cement composites with and without EPS spheres as a function of density.
  • FIG. 8 is a graph of compressive strength of a lightweight cement composite as a function of percent volume fraction EPS spheres.
  • FIG. 9 is a graph of Young's Modulus of lightweight cement composites with and without EPS spheres as a function of density.
  • FIG. 10 is a graph of Young's Modulus of a lightweight cement composite as a function of percent volume fraction EPS spheres.
  • FIG. 11 is a graph showing Modulus of Rupture with and without EPS spheres of lightweight cement composites as a function of density.
  • FIG. 12 is a graph of Modulus of Rupture of a lightweight cement composite as a function of percent volume fraction EPS spheres.
  • FIG. 13 is a schematic illustration of a batch process for casting structural panel faces and cores.
  • FIG. 14 is a cross section of a lightweight cement composite structural panel core.
  • FIG. 15 is a schematic illustration of a step in a process for bonding full density cement faces to a lightweight foam composite core to produce a structural panel including a lightweight foam composite core.
  • FIG. 16 is a schematic illustration of a step in a process for bonding full density cement faces to a lightweight foam composite core to produce a structural panel including a lightweight foam composite core.
  • FIG. 17 is a schematic illustration of a continuous production process for a structural panel.
  • FIG. 18 is a schematic illustration of simplified sandwich cell geometry. Description of the Preferred Embodiment
  • This invention provides a low density matrix composite characterized by a sandwich beam microstructure, a lightweight cement composite comprising lightweight aggregate particles dispersed in a matrix phase of cellular concrete, a method for making a lightweight cement composite and a structural panel including an inner low density matrix composite layer characterized by a sandwich beam microstructure.
  • a lightweight composite or low density matrix composite refers to a composite having a density in the range of from about 2 to about 14 pounds per cubic foot.
  • a low density matrix phase refers to a phase with a density in the range of from about 0.5 to about 30 pounds per cubic foot and a high density phase refers to a phase which has a density in the range of from about 85 to about 115 pounds per cubic foot.
  • a low density matrix phase 16 can be cellular concrete which consists of cement combined with a foam which is either introduced into a cement slurry as a preformed foam or is formed in situ by a foaming agent, included in the cement slurry, which reacts to form bubbles, thus entraining air during cement hydration.
  • a cellular concrete is characterized by voids, wherein air was initially entrained in the foam, surrounded by cement as shown schematically in FIG. 1 where a void 10 is surrounded by more dense material 12, which can be cement, to form a cell which is the basis for the term cellular concrete.
  • the low density matrix phase can also be a foam such as polyurethane, expanded polystyrene and polyethylene.
  • the densities of these foams would be in a range of from about 1 to about 10 pounds per cubic foot. If such foams are used as a matrix material instead of cellular concrete, the lightweight aggregate particles can include hollow glass spheres and spheres with a hard shell.
  • Void 10 is surrounded by hardened, dense material 12 of a composition corresponding to that of the foam or cement product used.
  • the low density matrix phase is selected from materials having a density in the range of from about o.5 to about 30 pounds per cubic foot.
  • the low density cellular matrix phase 16 density is typically in a range of from about 15 to about 30 pounds per cubic foot.
  • Polymer foams can have densities of less than l pound per cubic foot.
  • Aggregate phase particles 14 which can be organic material such as expanded polystyrene, recycled reground plastic foam; hollow polymeric spheres, cubes or other regularly shaped particles; inorganic material including hollow glass spheres such as silicate glass and borosilicate glass; and other hollow or low density cellular ceramic and steel spheres, cubes or regularly shaped particles with thin exterior walls, are embedded in low density matrix phase 16 to create the desired sandwich beam microstructure.
  • An important consideration in selecting aggregate particles is the ratio of particle wall thickness to overall particle dimensions. For a sphere, the ratio is in the range of from about .02 to about .001.
  • Preferred spherical aggregate particles have bulk densities less than 5 pounds per cubic foot.
  • aggregate particles 14 are shown as spherical in FIG. 1, aggregate particles can have other, including cubic, geometries. Cubic or spherical geometry aggregate particles are preferred because they have isotropic outer surfaces which pack so that a sandwich beam microstructure is formed when the interstitial low density matrix phase is confined between spheres. Cubic geometry aggregate particles are particularly preferred because the surfaces which they present to interstitial low density matrix phase 16 are isotropic and planar and thus capable of readily creating the sandwich beam microstructure.
  • the low density aggregate particles can consist of an aggregate phase material shell 20 surrounding an interior void or air-filled space 18 as shown in FIG. 2 or can be solid or cellular particles formed from a low density material.
  • the density of the aggregate particles can be in the range of from about 1 to about 10 pounds per cubic foot, preferably in the range of from about 1 to about 3 pounds per cubic foot.
  • FIG. 1 shows aggregate particles of uniform size, aggregate particles 14 need not necessarily all be identical in size and, instead, can display a size distribution which may in fact enhance their efficacy.
  • the particle size can be in the range of from about 0.5mm to about 6mm. For cubic aggregate phase particles, identical sizes are preferred, while for other regular shapes, a particle size distribution is preferred.
  • a cell 24 denoted by lines in FIG. 1 is defined by a cube drawn around a sphere which includes sandwich beam microstructural features formed with neighboring spheres.
  • aggregate particles 14 in this embodiment consist of a hollow interior space or void 18 surrounded by aggregate phase material shell 20 coated with a high density phase layer 22, such as cement which can contain fiber and other additives including silica fume, superplasticizers and polymer additives such as epoxy, latex and the like.
  • a high density phase layer 22 such as cement which can contain fiber and other additives including silica fume, superplasticizers and polymer additives such as epoxy, latex and the like.
  • high density layers 22 is interstitial cellular matrix phase 16, in this embodiment, cellular concrete.
  • the sandwich beam microstructure is thus formed by "sandwiching" low density cellular matrix phase material between high density layers 22 which is analogous to a conventional macroscopic sandwich beam which typically consists of two, thin, stiff skins such as steel or wood separated by a low density core of polymer foam or honeycomb material.
  • Sandwich beam microstructure further requires selecting a material for the high density layer 22 which is at least five times denser than that of the material making up low density matrix phase 16. These density criteria insure that the sandwich beam microstructural features function in the same manner as a conventional macroscopic sandwich beam.
  • the sandwich beam microstructure extends over a scale of from about 0.5mm to about 6mm at a scale of a single cell, 0.1mm to 1mm at a scale of a single cell wall beam between aggregate particles and greater than 6mm at the scale of many cells with the high density phase layer 22 having a thickness in the range of from about 20 microns to about 100 microns surrounding aggregate phase particles having a particle size in the range of from about 0.5mm to about 6mm in diameter and characterized by a particle size distribution having a breadth in the range of from about 0.5mm to about 6mm.
  • the lightweight cement composite provided includes lightweight aggregate particles, present in quantities in a range of from about 40 to about 50% volume fraction of the composite and having the density, geometry, size and other characteristics a.lready discussed, dispersed in a matrix phase of cellular concrete.
  • the lightweight cement composite can further include fiber which can be a polymer fiber, such as a polyester and a polypropylene fiber and an inorganic fiber such as a glass fiber.
  • Typical glass fibers used in a cement matrix include silicate and borosilicate glass fibers, standard E-glass and alkali resistant glass fibers.
  • Fibers generally have a strand-like geometry, are in the range of from about 0.25 to about 1.5 inches in length and are present in concentrations in the range of from about 0.3% by weight of cement to about 1.0% by weight of cement. Fiber length and fiber concentration are kept within these ranges to avoid problems in mixing the resulting cement slurry with the foam.
  • a large volume of low density, preferably 3 pounds per cubic foot, preformed foam is mixed with the cement slurry.
  • the fiber tends to separate out from the slurry and clump at the bottom of the mixing vessel when foam and slurry are combined. Longer fibers also are more likely to clump together than are shorter fibers.
  • the cellular concrete occupies interstitial space between the aggregate particles.
  • the cellular concrete includes a cement and a foam which can be preformed or formed in situ.
  • the cement can be a high early strength cement such as a Portland Type III cement, a Normal Portland Type I cement, or any type of cement chemically compatible with the preformed foam so that foaming action is not inhibited and entrained air is not eliminated. For example, rapid hardening high gypsum content cements are to be avoided because they cause the foam to loose its aeration.
  • the preformed foam can include an inorganic foam; stabilized organic foam; hydrolyzed protein based foam, including sodium lauryl, cetyl, and oleyl sulfates; sodium naphthalene isopropyl sulphate; sulfates of petroleum derivatives; complex organic compounds further including keratin compounds, and saponin; and inorganic compounds stabilized with organics such as the commercial foam concentrate products ElastizellTM and EMGTM both made by Elastizell Corporation of America, Ann Arbor, MI.
  • the foam can be formed in situ by the reaction of lime in the cement slurry with finely powdered metals such as aluminum and zinc.
  • the powdered metals react with lime in the slurry during cement hydration to form bubbles resulting in desired air entrainment.
  • the volume of entrained air needed is in the range of about 75-85% of the total volume of the foam.
  • other in situ foaming agents are foam concentrate, added undiluted, to the cement slurry and then agitated vigorously with the slurry.
  • Foams can be based on metals (e.g., aluminum, nickel and copper) or ceramics (e.g., Sic and glass).
  • the lightweight cement composite can also contain other additives including silica fume, such as Force
  • silica making up silica fume can fill voids between hydrated cement grains reducing the permeability of cements, and may result in some increase in compressive strength.
  • silica fume can increase foam cohesiveness during setting, thus resulting in higher composite strength.
  • Superplasticizers reduce the amount of water required in the slurry to maintain a flowable, workable slurry consistency. The lower water/cement ratio required to produce this workable slurry consistency produces a cement paste characterized by higher stiffness and strength.
  • Polymer additives such as latex and epoxy can increase cement tensile strength, toughness and ductility.
  • This lightweight cement composite is characterized by a sandwich beam microstructure which contributes to its superior mechanical properties including a compressive strength in a range of from about 45psi to about 60psi, a Young's modulus in the range of from about 18,000 psi to about 25,000 psi, a modulus of rupture in the range of from about 35 psi to about 55 psi, and a density between 11 and 14 pounds per cubic foot to make the lightweight composite suitable for use as a core material in a load-bearing structural member.
  • a method for making a lightweight composite includes forming a slurry including cement and water, mixing lightweight aggregate particles into the slurry so that the aggregate becomes completely coated with the slurry mixture, introducing a foaming agent into the aggregate/slurry mixture, molding the foamed mixture into a shaped article and curing the shaped article.
  • the characteristics of the cement, lightweight aggregate particles and foaming agent have already been described.
  • the slurry can further include other additives such as fiber, silica fume, superplasticizer and polymer additives such as epoxy and latex which have also already been described in greater detail.
  • the slurry can be prepared by dry mixing cement and fiber with silica fume and a superplasticizer and adding water to the silica fume and superplasticizer solution to form a cementitious . slurry as a final step.
  • dry mixed cement and fiber can be wet by combining them with premixed water, silica fume and superplasticizer to form a slurry.
  • the slurry produced according to either of these two methods can then be combined and thoroughly blended with a preformed foam while care is taken to retain foam aeration.
  • the foam concentrate would be added to the water/silica fume/superplastizer solution and then mixed vigorously with the cement to create a foamy slurry. It is desirable that the cement be fully hydrated. Sufficient water is used in forming the slurry to produce a water/cement ratio in the slurry of approximately 0.6. Since the superplasticizer functions as a surfactant, its concentration is kept below approximately 0.5% by weight of cement to avoid disruption of the foam.
  • This method for making a lightweight composite can be used for preparation of large or small composite batches and can be scaled up or down using mixing apparatus appropriate to the mass of composite being prepared without adversely impacting properties of the resulting composite.
  • the composite slurry can be handled using conventional techniques including pumping.
  • a structural panel which includes facing layers which can be made of a structural building material such as cement, wood, plywood, oriented strand board, waferboard and fiber reinforced cement board or a non-structural material such as gypsum wallboard.
  • the facing layers can be bonded to opposing faces of an inner low density matrix composite layer having characteristics already described using adhesives such as epoxy, silicone and latex; cement hydration when bonding a cement face to a cement core and mechanical fasteners such as embedded clips, bolts and couplings.
  • Materials for the facing layers are selected according to the panel's end use as a wall panel, roof panel or foundation panel.
  • Foundation panels can be constructed with cement board on both faces bonded to a cement foam composite core.
  • Roof panels can have cement, steel or wood faces bonded to the cement foam composite core.
  • Wall panels could use cement, wood or steel faces bonded to the core, as well.
  • the ratio of the relative thicknesses of the first facing layer with respect to the inner lightweight composite foam layer and to the second facing layer can also be adjusted depending upon the intended panel use.
  • cement board faces in a range of from about 1/2" to about 3/4" thick can be bonded to cores in a range of from about 6" to about 8" thick.
  • Wall panels can be made from wood and/or cement faces in a range of from about 1/2" to about 3/4" thick bonded to a core in a range of from about 2" to about 6" thick.
  • Roof panels can have in a range of from about 1/2" to about 3/4" thick faces of cement or wood bonded to a core in a range of from about 6" to about 12" thick.
  • Steel faces, less than 1/16" thick can also be used for faces on wall and roof panels, with cores from in a range of from about 2" to about 12" thick. Face and core thicknesses are determined by a combination of structural and thermal insulation requirements, and can depend on factors such as the roof span, loading conditions and thermal insulation requirements.
  • the structural panels can be provided with means for fastening individual panels together with the particular fastening means selected according to panel use as a wall, roof or foundation panel.
  • Foundation panels with cement skins can be grouted together using a shear key type joint or fastened using mechanical fasteners such as embedded clips, bolts and couplings.
  • Wall panels with cement faces can be fastened in the same manner as foundation panels.
  • Wall panels with wooden faces can be fastened using a spline system similar to that used in current residential sandwich panel construction.
  • Panels with steel faces can use connections well known in the art and currently used for joining steel-faced sandwich building panels.
  • Example I A lightweight cement composite characterized by a sandwich beam microstructure was prepared by dry mixing in a standard bakery type mixing machine five pounds of Portland Type III cement and 0.017 pounds polyester fiber until the mixture had the appearance of greenish-flour. Next, 2.625 pounds of water at 120°F ⁇ 5°P, were pre ⁇ mixed with 0.73 pounds silica fume solution such as (Force 10,000TM made by W.R. Grace and Co., Cambridge Massachusetts and 0.025 pounds superplasticizer ZIPTM, Elastizell Corp. of America, Ann Arbor, MI, a surfactant which changes the surface tension to provide a more workable consistency for the cement while reducing the water needed to produce a slurry of workable consistency.
  • silica fume solution such as (Force 10,000TM made by W.R. Grace and Co., Cambridge Massachusetts and 0.025 pounds superplasticizer ZIPTM, Elastizell Corp. of America, Ann Arbor, MI, a surfactant which changes the surface tension to provide a more workable consistency for the cement while reducing the water needed to produce
  • the water/cement ratio of the slurry used in this embodiment of the invention was 0.6.
  • the final water cement ratio for the cement foam composite was 0.8.
  • the cement foam composite has a higher water content than the slurry because it includes water incorporated into the cement from the aqueous preformed foam during hydration.
  • Expanded polystyrene (EPS) spheres were intermixed with the slurry until they were completely coated. The slurry coating hardens to form the high density phase of the composite.
  • EPS expanded polystyrene
  • the cement slurry and slurry-coated EPS spheres were then transferred to a mechanical mixer operated at approximately 60 RPM and a preformed foam was injected.
  • the EPS spheres must be completely wetted with the full density cement slurry before introduction of the foam.
  • a mechanical mixer was used for this stage of the mixing process and it was operated at a slow speed to preserve air entrained within the preformed foam.
  • the combined cement slurry, EPS spheres and foam mixture was further mixed for at least one minute to completely incorporate the foam within the slurry containing the EPS spheres but for not longer than eight minutes because mixing beyond eight minutes can crush the foam.
  • the foamed cement slurry was mixed for one minute mechanically, for one minute by hand, and for another minute with the mechanical mixer.
  • the foam was prepared from a liquid concentrate, (EMGTM, Elastizell Corporation of America, Ann Arbor, MI) in a proportion of one part foam concentrate to thirty parts water to form an aqueous based foam solution.
  • EMGTM Elastizell Corporation of America, Ann Arbor, MI
  • the strength of the resulting foam is determined by the concentration of foam concentrate used.
  • the foam solution concentration can be in the range of from about 1 part foam concentrate to about 20 parts water by volume to about 1 part foam concentrate to about 40 parts water by volume.
  • the aqueous foam solution was placed in a thirty gallon boiler tank connected to compressed air tanks operated at 100 psi and air was blown into the foam solution at a rate of thirty cubic feet per minute to produce a foam having the appearance of shaving cream, but very stiff and able to maintain a percentage of entrained air in the range of from about 75% to about 85% of the total volume of the foam within the foam bubbles.
  • the foamed mixture was poured into styrofoam molds to produce three inch by six inch cylinders. The cylinders began to harden in about two hours, becoming warmer as hydration began to occur. After curing overnight, the cylinders were hard to the touch and it was possible to tap on a cylinder surface; however, they were not near their full strength.
  • the cylinders were placed in a curing chamber having a relative humidity in the range of from about 80% to about 95% at room temperature for 7 days. Samples were then removed from the styrofoam molds and returned to the curing chamber for six days, air dried on the thirteenth day and tested on the fourteenth day after they were originally poured.
  • the cylinders exhibited standard cement hydration behavior with the use of Portland Type III cement enabling attainment of high early strength, approximately 80% of the material's ultimate strength, during the fourteen day cure. It is assumed for such material, that after 28 days, full strength is reached. Beams of the lightweight composite material were also successfully molded and cured.
  • FIG. 3 is a scanning electron microscope
  • FIG. 4 is a micrograph showing the sandwich beam microstructure depicted schematically in the expanded view of FIG. 2.
  • Cement foam matrix material 32 intervenes between EPS spheres 30 forming the sandwich beam microstructure.
  • FIG. 5 is an SEM micrograph showing a 19.3 micron thick high density cement coating 36 which surrounds EPS void 30 which is filled with polymethylmethacrylate (PMMA) .
  • PMMA polymethylmethacrylate
  • FIG. 6 shows a 54.2 micron thick high density cement coating 36 surrounding an EPS sphere 30.
  • Cement foam cells 34 are formed in matrix material 32.
  • FIGS. 5 and 6 show a lightweight composite having a cement foam matrix material 32 characterized by a density in the range of from about 18 to about 20 pounds per cubic foot wherein the EPS spheres are embedded.
  • the EPS spheres themselves have a thin coating 36 of full density cement in the range of from about 20 to about 100 microns thick.
  • a sandwich beam microstructure results as shown in FIG. 4 and schematically in FIG. 2.
  • the full density cement coating on the EPS spheres acts as a stiff material and the matrix material acts as a low density core and together they form a sandwich beam microstructure.
  • This sandwich beam microstructure gives improved stiffness and strength per unit weight by comparison with conventional cement foam composites lacking the sandwich beam microstructure.
  • FIG. 7 shows compressive strength as a function of overall lightweight foam composite density for composites including EPS spheres shown by points with error bars, and for composites without EPS spheres shown by triangles and having a cellular matrix phase material density in the range of from about 18.3 to about 21.9 pounds per cubic foot. It is clear from FIG. 7, that a lightweight foam composite containing EPS spheres exhibits a greater compressive strength than a lightweight foam composite of equivalent overall density, but not containing EPS spheres. This effect is particularly marked at densities less than 14 pounds per cubic foot.
  • FIG. 7 shows compressive strength as a function of overall lightweight foam composite density for composites including EPS spheres shown by points with error bars, and for composites without EPS spheres shown by triangles and having a cellular matrix phase material density in the range of from about 18.3 to about 21.9 pounds per cubic foot.
  • the compressive strength of a lightweight cement composite containing above 55% volume fraction EPS spheres declines, since at this concentration of EPS spheres, the compressive strength of the composite is dominated by the compressive strength of the EPS spheres which are characterized by a compressive strength of approximately 30 psi.
  • FIG. 9 shows Young's Modulus as a function of overall lightweight foam composite density for lightweight foam composites with EPS spheres and without EPS spheres, both including a cellular matrix phase material characterized by a density in the range of from about 18.3 to about 21.9 pounds per cubic foot.
  • FIG. 10 shows Young's Modulus as a function of percent volume fraction EPS spheres for a lightweight foam composite including a matrix phase characterized by a density in the range of from about 18.3 to about 21.9 pounds per cubic foot and shows that Young's Modulus is initially decreased relative to the Young's Modulus of cellular concrete without EPS spheres upon addition of EPS spheres but increases up to about 50% volume fraction EPS spheres in a manner similar to the observed compressive strength behavior.
  • FIG. 11 shows modulus of rupture data as a function of overall lightweight foam composite density for lightweight foam composites with EPS spheres, shown by circles with error bars, and for lightweight foam composites without EPS spheres, shown by triangles, with both lightweight foam composites including a cellular matrix phase characterized by density in the range of from about 20.8 to about 23.4 pounds per cubic foot.
  • FIG. 12 shows modulus of rupture data as a function of percent volume fraction EPS spheres for a lightweight foam composite including EPS spheres and characterized by a matrix density in the range of from about 20.8 to about 23.4 pounds per cubic foot and indicates that the modulus of rupture increases substantially monotonically with EPS sphere addition.
  • EXAMPLE II Structural panels having full density cement faces can be prepared using a batch method involving two separate batch processes.
  • a first batch process is for casting the full density cement faces and a second batch process is for casting the lightweight foam composite cores.
  • full density cement faces are cast in battery mold 40 as shown in Fig. 13 mounted on rollers 42 which allow battery mold 40 to roll beneath mixer hopper 44 so that compartments 46 can be filled with full density cement to cast full density cement faces not shown.
  • Battery mold 40 is typically characterized by length 48 of approximately 8 feet, height 50 of approximately 4 feet and overall width 51 of approximately 4 feet divided into compartments 46 each having a width of approximately 3/4 inch when mold 40 is used for casting a full density cement face or approximately 8 inches when mold 40 is used in casting a lightweight foam composite core.
  • a full density cement mixture is made by combining cement, silica sand, fiber, fly ash, silica fume, water and other additives in a mixer.
  • the mixture is poured into battery mold 40 from mixer hopper 44 to fill compartments 46 with full density cement to form full density cement faces.
  • the faces are allowed to cure in battery mold 40 overnight and then are stripped from the mold and stacked for curing, allowing reuse of battery mold 40.
  • two battery molds, each capable of casting 16 full density cement faces are needed to produce 512 square feet of total panel output.
  • water, cement, fiber, and other additives are combined in a slurry pre-mix.
  • the pre-mix is further mixed with EPS spheres.
  • Compartments 46 of battery mold 40 are then filled with the slurry, EPS and foam mixture to cast lightweight foam composite core billets not shown. Billets are allowed to set up in the mold for twelve hours and are then stripped from the mold and cured for a period of fourteen days. In a typical process, 6 lightweight foam composite core billets, each 8 inches thick, can be poured into a single battery mold. Other mold dimensions and arrangements can readily be used in the process.
  • lightweight foam composite core 60 and face panel 67 can be lowered as by the use of jacks, so that core lower surface 69 is in contact with upper surface 74 of panel 66 and so that core upper surface 70 is in contact with a lower surface not shown of face panel 67.
  • Light pressure less than 1 psi, is applied and the bonded panels are allowed to cure for approximately 30 minutes as shown in FIG. 16.
  • Adhesives suitable for this bonding process include epoxy, silicone and latex, and are well known in the art. After the approximately 30 minute cure is complete, the bonded structural panel is removed from frames 68 and stand 64, stacked and cured overnight before shipping.
  • Example III Alternatively, a continuous process can be used to fabricate structural panels including a lightweight composite core. Such a continuous fabrication line is shown schematically in FIG. 17.
  • Full density cement for forming a full density cement face on the structural panel is mixed as already described in Example II and supplied from continuous mixer 80 to produce panel bottom face 82 which can be in the range of from about 1/2" to about 3/4" thick.
  • the continuous mixer for full density cement application can be replaced with rolled steel.
  • Screed 84 acts as a leveling bar to smooth the full density cement supplied by continuous mixer 80.
  • a second continuous mixer 86 continuously supplies lightweight foam composite mixture 88 which is produced according to the method already described in Example II and is leveled by screed 90 to produce lightweight foam composite panel core 92.
  • a third continuous mixer 94 applies full density cement for a full density top face which is leveled by screed 96 to form top panel face 98 which can be in the range of from about 1/2" to about 3/4" thick.
  • Conveyor 100 moves sufficiently slowly to allow panel material to spend approximately 1 hour on the conveyor so that the cement can begin hardening before cutting by cutter 102 to form structural panel 104 including a lightweight foam composite core 92. Structural panel 104 is then transferred to a curing chamber on rack 106. Practical production considerations require very rapid setting cement or a very long conveyor.
  • the lightweight foam composite core is characterized by a higher water/cement ratio than is the full density cement face material. High cement shrinkage during drying, and a shrinkage differential between the faces and core may cause cracking of the structural panel if the face and core are sequentially cast wet and uncured in contact with each other as according to the already described continuous production process.
  • the structural panels described in Examples I and II include a sandwich beam microstructure as shown schematically in FIGS. 1 and 2 and as observed in the composites of the invention and shown in SEM micrographs of FIGS. 3-6.
  • a relationship can be developed to serve as a guide for design of a sandwich beammicrostructure based on t f , thickness 113 of sandwich beam faces 112, t c , thickness 115 of beam foam core 114, E f , the Young's Modulus of faces 112, G c , the shear modulus of core 114 and I, the overall length 116 of the sandwich cell.
  • Sandwich beam microstructure will be produced when the criterion

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Abstract

Composites légers comprenant des particules de granulat (14), un milieu à densité élevée entourant lesdites particules (14) ou constituant une enveloppe extérieure mince d'une particule de granulat (14) et un milieu de matrice à faible densité (16) occupant l'espace interstitiel entre les particules de granulat (14), de façon à produire une cellule (24) ou une microstructure de poutre composée. L'invention décrit un composite de ciment léger et un procédé de fabrication dudit composite, ainsi que des panneaux de construction comprenant une couche de composite léger caractérisée par une microstructure de poutre composée. Le milieu de matrice à faible densité (16) peut être un béton cellulaire caractérisé par un vide (10) entouré par un matériau plus dense (12) pouvant être du ciment.
PCT/US1992/010276 1991-11-26 1992-11-20 Composites legers WO1993010972A1 (fr)

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US79912091A 1991-11-26 1991-11-26
US07/799,120 1991-11-26

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6620487B1 (en) 2000-11-21 2003-09-16 United States Gypsum Company Structural sheathing panels
WO2004087605A1 (fr) * 2003-04-01 2004-10-14 Sprungala Hubert Beton leger et procede de fabrication associe
WO2006037187A1 (fr) * 2004-10-08 2006-04-13 E.I.F.S. Holdings Limited Mélanges de cimentation améliorés
WO2011101595A1 (fr) * 2010-02-18 2011-08-25 Lafarge Plaque legere de ciment
FR2963002A1 (fr) * 2010-07-23 2012-01-27 Lafarge Sa Plaque legere de ciment
US8394744B2 (en) 2009-05-22 2013-03-12 Lafarge Low density cementitious compositions
RU2494079C1 (ru) * 2012-07-17 2013-09-27 Юлия Алексеевна Щепочкина Сырьевая смесь для изготовления легкого бетона
US8997924B2 (en) 2007-03-21 2015-04-07 Ashtech Industries, Llc Utility materials incorporating a microparticle matrix
US9076428B2 (en) 2007-03-21 2015-07-07 Ashtech Industries, Llc Sound attenuation building material and system
CN110451856A (zh) * 2019-08-02 2019-11-15 安徽海龙建筑工业有限公司 一种预制结构装饰一体化内隔墙板及其制备方法
CN112694279A (zh) * 2021-01-05 2021-04-23 广东科学技术职业学院 一种具有核壳结构的轻集料及其制备方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3272765A (en) * 1964-05-18 1966-09-13 Koppers Co Inc Lightweight concrete
US3758319A (en) * 1970-10-22 1973-09-11 Stanley Works Method for forming foamed concrete structures
JPS524531A (en) * 1975-06-30 1977-01-13 Showa Denko Kk Manufacturing of light foamed concrete
US4303730A (en) * 1979-07-20 1981-12-01 Torobin Leonard B Hollow microspheres
US4373955A (en) * 1981-11-04 1983-02-15 Chicago Bridge & Iron Company Lightweight insulating concrete
US4588443A (en) * 1980-05-01 1986-05-13 Aktieselskabet Aalborg Pottland-Cement-Fabrik Shaped article and composite material and method for producing same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3272765A (en) * 1964-05-18 1966-09-13 Koppers Co Inc Lightweight concrete
US3758319A (en) * 1970-10-22 1973-09-11 Stanley Works Method for forming foamed concrete structures
JPS524531A (en) * 1975-06-30 1977-01-13 Showa Denko Kk Manufacturing of light foamed concrete
US4303730A (en) * 1979-07-20 1981-12-01 Torobin Leonard B Hollow microspheres
US4588443A (en) * 1980-05-01 1986-05-13 Aktieselskabet Aalborg Pottland-Cement-Fabrik Shaped article and composite material and method for producing same
US4373955A (en) * 1981-11-04 1983-02-15 Chicago Bridge & Iron Company Lightweight insulating concrete

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6620487B1 (en) 2000-11-21 2003-09-16 United States Gypsum Company Structural sheathing panels
WO2004087605A1 (fr) * 2003-04-01 2004-10-14 Sprungala Hubert Beton leger et procede de fabrication associe
WO2006037187A1 (fr) * 2004-10-08 2006-04-13 E.I.F.S. Holdings Limited Mélanges de cimentation améliorés
US8997924B2 (en) 2007-03-21 2015-04-07 Ashtech Industries, Llc Utility materials incorporating a microparticle matrix
US9076428B2 (en) 2007-03-21 2015-07-07 Ashtech Industries, Llc Sound attenuation building material and system
US8394744B2 (en) 2009-05-22 2013-03-12 Lafarge Low density cementitious compositions
WO2011101595A1 (fr) * 2010-02-18 2011-08-25 Lafarge Plaque legere de ciment
FR2963002A1 (fr) * 2010-07-23 2012-01-27 Lafarge Sa Plaque legere de ciment
RU2494079C1 (ru) * 2012-07-17 2013-09-27 Юлия Алексеевна Щепочкина Сырьевая смесь для изготовления легкого бетона
CN110451856A (zh) * 2019-08-02 2019-11-15 安徽海龙建筑工业有限公司 一种预制结构装饰一体化内隔墙板及其制备方法
CN112694279A (zh) * 2021-01-05 2021-04-23 广东科学技术职业学院 一种具有核壳结构的轻集料及其制备方法
CN112694279B (zh) * 2021-01-05 2022-04-19 广东科学技术职业学院 一种具有核壳结构的轻集料及其制备方法

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