IE42359B1 - Composite building module - Google Patents

Description

This invention relates to a composite building module which is similar to monolithic cast concrete modules in outward appearance and use, yet has significant improvements in insulating properties and weight reduction.

More particularly, this invention relates to a composite building module having a rigid foam core, such as a rigid urethane polymer foam, encased or encapsulated in a shell made of a hardened mixture of cement and fibres, such as glass fibres.

Because of increased costs in material and labour, the construction industry has come to use prefabricated building modules, for example wall panels, roof decks and the like. A popular form of construction is known as curtain-wall construction and involves the use of a structural steel skeleton which is faced with stacked-up, prefabricated or precast panels. Such curtain-wall panels are commonly cast from reinforced concrete and are provided with-a surface finish such as a smooth concrete finish or aggregate imbedded into the face of the panels. These panels are extremely heavy, for example a 4 x 8 curtain-wall panel cast from reinforced concrete weighs from 1400-1600 lbs., and require heavy construction equipment to install. Xn addition, these panels provide very poor insulating properties and by themselves are a poor vapour barrier. This necessitates further construction to insulate and seal the stacked-up curtain-wall of precast concrete modules. - 3 The construction industry has long sought improved building elements that will offer advantages in material and construction costs. A laminated structural element is described in Muhim patent, U.S. 3,295,278, issued January 3, 1969, as consisting of (i) a preformed plastic foam layer, (ii) one or more covering layers of aqueous binding material hardened to impart the strength required for a structure where the structural element is to be used, and (iii) mechanical meahs interlocking the foam covering layers into a unitary element. Heat insulation is imparted by the plastic foam layer while the required structural strengths‘are provided by the covering layer or layers.

In one embodiment a preformed plastic foam layer is sandwiched between two concrete layers which are connected through openings in the foam layer by a multiplicity of concrete dowels thereby interlocking the layers mechanically. In another embodiment, a covering layer of a hardened cement having a reinforcement of wood fibres therein is mechanically interlocked by a multiplicity of micro-dowels formed by the binder in surface crevices of the preformed plastic foam layer. The so-called wood fibres providing the micro-dowels have a length of 35-50 cm (approximately 14-20 inches).

Another proposal for a laminated insulating panel is set forth in British Patent Specification No. 1,030,333 and involves a preformed insulating layer which is surfaced on one or both sides with at least two layers of cement between which is embedded a glass fibre fabric web. The insulating or core layer, which can carry a static load, is made from a mixture of Portland Cement, an aqueous - 4 plastic dispersion, sand and a lesser amount of waste foam formed when foamed plastic parts are sawed. The covering layers are made of similar mixture without sand using greater amounts of waste foam.

A real problem encountered in making laminated panels using preformed plastic foam cores (e.g., polystyrene foam) is the lack of adhesive bond between the core and the covering layer. Muhim attempts to cope with this by providing a mechanical interlocking using dowels or micro-dowels to form a unitary element. He also contemplates an extra bonding film to improve adhesion. In the British Patent, the covering layers contain a binder which will provide a bond with the insulating core. The use of like materials in both the core and the covering layers makes this possible.

According to one aspect of the present invention a composite building module comprises a rigid foam core, encased in an enclosed shell made from a hardened mixture of cement and fibres, said core being formed by foaming a foamable polymer composition in a shell having one open side followed by forming a cover for the open side over the core to close the shell with the core encased therein, said core being adhesively interlocked via the in situ foaming with the shell.

The building module of the present invention is extremely light in weight as compared to precast concrete panels for example, and has greatly improved insulating and vapour barrier properties per se. Because the present invention utilizes an in situ foamed core, an adhesive interlock between core and shell is formed which is stronger than either material by itself. The chemical - 5 42351, foaming reaction that takes place, plus the fact that foaming takes place in an enclosed shell under retention, results in an overall intimate adhesive interlock and a prestressed structure wherein the shell is under tension and the core is under compression. This means that the shell and core are now united together into a monolithiclike structure that has far greater strengths (because of the overall adhesive interlock) than prior laminated panels using preformed foam plastic cores, and, at the same time, is light in weight and has excellent insulating and vapour barrier properties.

The core of rigid foam is preferably a rigid urethane polymer foam core. The shell preferably contains from about 1 to 40% by volume of fibres, more preferably 2 to 15% by volume glass fibres, having a length of from 1/8 to 1 inch, preferably from 3/8 to 1 inch, and being substantially uniformly distributed in a random fashion throughout substantially the entire volume of said shell said core being formed within the enclosed shell by the chemical reaction of components of a foamable polymer composition which is foamed in situ under pressure to form an encased rigid foam core intimately adhesively interlocked, via the in situ foaming reaction, over its entire surface area with the shell over its entire interior area. The in situ foaming reaction under pressure results in a module with a rigid core under compression and an encasing shell under tension.

The exterior of the shell can be provided with any desired surface finish including aggregates such as stone or marble chips embedded in one or more surfaces thereof and the module can be used in the same manner as precast - 6 concrete modules, without, however the need for heavyconstruction equipment and further steps to impart insulating and vapour barrier properties thereto.

According to another aspect of the invention we provide a process for making a composite building module which comprises forming a supported shell having one open side from a hardened mixture of cement and fibres, introducing a foamable polymer into said open shell thereby filling the shell with a polymer foam, thereafter applying a cover for the open side over the foamed core to close the shell with the core encased therein using a hardenable mixture of cement and fibres and curing said cover.

Because the shell is enclosed, foaming within the interior takes place under pressure and this, plus the chemical foaming reaction, contribute to the formation of the adhesive interlock between the core and the shell and the creation of a prestressed structure. In situ foaming within the enclosed shell involves restraint during the act of foaming which is a dynamic, expansive operation.

The force of expansion causes the foam to penetrate the pores of the reinforced cement shell. The phrase adhesive interlock” is used herein to describe this and will be understood as the interfacial penetration of the rigid foam core into the shell interior to unite the two into a monolithic-like unit through a combination of mechanical, chemical and adhesive forces.

The present invention will be more fully understood from the following description taken in conjunction with the accompanying drawing wherein:Figure 1 is a cross-sectional view of a typical composite building module of the present invention; - Ί Figure 2 is a cross-sectional view partly in perspective and partly broken away of a composite building module of the invention shown in the form of a highway barrier with a weighted base; and Figure 3 is a perspective view partly broken away of a partly assembled building illustrating various ways in which the composite module of the invention can be utilized in the construction of a building.

Preferred hardenable mixtures for the invention are mixtures of cement, inert particulate filler and glass fibres containing 5-50% or more by volume glass fibres. Mixtures of cement and fibres with lengths of from 1/8 to 1 inch, or longer, can be used in the invention. Suitable fibres, in addition to glass fibres, include organic and inorganic synthetic fibres such as Dacron (Trade Mark), Nylon, graphite and the like. Suitable inert particulate fillers include sand, pumice, stone dust, and the like. They can be used in amounts of from to 30% by volume.

The cement/fibre mixtures can contain conventional additives such as lime and sterates for water resistance and latex for added strength.

Suitable rigid foams include inorganic and organic foams. Preferred are foams that can be formed in situ such as rigid polymer foams. Rigid urethane foams are preferred and are well-known and widely used principally for insulation purposes. Such foams are commonly created on site by combining the reactants (a polyol and an isocyanate) using air-less spraying or liquid application techniques. Foaming commences almost instantaneously and is completed within a very short period of 23 5 9 - 8 time, depending on the type of urethane composition employed. The density of rigid urethane foams also depends on the nature of the urethane composition employed but generally ranges between 1.5 lbs. per cu. ft. to 10 lbs. per cu. ft., more commonly from 2 to 5 lbs. per cu. ft. Because of the lightweight closed cell structure of rigid urethane foams, they also have structural strength. Other suitable rigid foams include polyester foams, phenolic resin foams, isocyanurate foams, and the like.

The present invention provides a surprisingly strong and self-supporting building module which is light in weight and has outstanding insulating and vapour barrier properties.

The invention will now be described with reference to the drawing and the preferred embodiment of a rigid urethane foam polymer core and a cement/glass fibre shell.

Figure 1 of the drawing shows a typical building module in cross-section and the component parts are shown in exaggerated proportions for ease in understanding.

Thus, the building module of the invention has a rigid urethane polymer foam core 14 enclosed encapsulated in a shell 12 made of a hardened mixture of cement and glass fibres. The finished, monolithic-like module is indicated generally by the reference numeral 10. Figure 2 shows a particular application wherein the building module is in the form of a highway barrier in which base 16 includes a concrete forming aggregate.

An important feature of the present invention is the encapsulation of the rigid foam core 14 by the outer shell 12 and the formation of an intimate adhesive bond 11 between the core 14 and the shell 12 preferably over 2 3« s the entire surface area of the core 14 but depending on how the module is made, the intimate adhesive bond can be formed over a major portion of the interface between the core 14 and the shell 12. Because the rigid foam core 14 is formed in situ, the foaming rigid urethane polymer enters and fills surface irregularities such as pores and surface outlined glass fibres and provides an intimate, preferably overall, rigid interfacial adhesive interlock between the rigid foam core and the shell 12.

Depending on the intended use for the building module of the invention, the shell 12 can have a thickness ranging from about 1/8 inch to 1 inch, or more. The thickness can be greater or less than this range again, depending upon the ultimate use intended for the building module.

For curtain-wall panels, the shell 12 preferably has a thickness of from 1/4 inch to 3/8 inch.

Likewise, the rigid foam core 14 can range in thickness from about 1 inch to 10 inch or more and this can be greater or less depending on the structure involved and the intended use. The building modules themselves can be made in almost any size ranging from small modular units up to relatively large curtain-wall units or roof deck members.

Figure 3 shows just a few of the many ways in which the building module of the invention can be employed. Because building modules of the invention are like monolithic modules in outward appearance and use, yet selfinsulating, the modules of the invention can be used in the same fashion using the same construction and installation techniques as monolithic concrete modules. Thus, the composite module of the invention 10 can be used as a wall 423SS - 10 panel or roof deck member as shown in Figure 3. The wall panels can be provided with window openings as in panels 18 and 22 or door openings as per panel 20. The modules of the invention can also be used as interior partition wall panels 24 as well as other numerous uses. Because of the light weight of the module of the invention, great savings can be realised in the load bearing structure of buildings. Thus, for example, in a multi-storey, curtain-wall building, considerably less structural steel will be needed to support the exterior panels as compared to the structural steel required to support precast concrete panels.

The facing surfaces of the composite panel 10 can be provided with any finish, texture or design which can be imparted via the finish or design of the mould surfaces or by imbedding or adhering aggregate such as gravel, broken stone, marble chips and the like to one or more surfaces of the shell 12. It is also possible to incorporate aggregate such as sand, gravel, broken stone and marble chips into the mixture of cement and glass fibres before forming the shell 12 for increased strength and also to attain desired surface textures or finishes.

The composite building module as shown for example in Figure 1 can be made by forming an open supported shell 12 having a bottom and side walls and open at the top.

A wooden form can be built Up to define one face and the side and end walls of a 4' x 8' panel and a trowelable mixture of cement and 35-45% by volume glass fibres can be applied by hand to the interior surfaces of the wooden form thereby building up the shell 12 to the desired thickness, for example, from 1/8 inch up to 1/2 inch thick or greater. The core 14 can then be formed in situ - 11 using an air-less spraying technique until the foam is built up to the top of the open shell. The foam can then be trimmed and the remaining face of the panel 12' applied by hand using the same trowelable cement/glass fibre composition. Forming the building module in this fashion ensures an intimate adhesive bond as described previously with the end and side walls and one face of the shell. Because the core is already formed when the complete face of the shell 12 is applied, the adhesive bond is not as strong as the intimate interfacial adhesive bond formed by ΐϋ situ foaming of the rigid foam.

As is known, a liquid or flowable urethane polymer composition exerts an outward pressure when caused to foam within a confined space such as the shell and this can be used to advantage in the present invention to ensure and promote an intimate overall rigid interfaoial interlock between the entire exterior surface area of the rigid foam core 14 and the entire interior surface area of the shell made of a hardened mixture of cement and glass fibres and create a stable structural stress throughout the module.

In a preferred embodiment, hot wet cement (made with water at about 12O-2OO°F, e.g., 180°F) without glass fibre is applied to or sprayed into the interior of the moulds which already has a lining of glass fibre chopped from continuous rolls and sprayed or applied to the interior of the moulds. The moulds can then be vibrated to disperse the lighter glass fibres through the wet cement to obtain uniform distribution throughout the entire volume of the cement layer in the moulds. Because the glass fibre is lighter, it rises in the wet cement; 43359 - 12 vibration is stopped when distribution is complete. Following this, or at the same time, the mixture of glass fibre and cement in the moulds can be pressed with a forming member to distribute the cement/glass fibre mixture within the interior of the moulds. Also, if desired, suction can be applied to the mould walls to remove water.

At the same time the glass is chopped and sprayed, a coating can be applied thereto by spraying, for example, with a polyester in a water-miscible solvent such as alcohol, to impart alkali resistance to the fibres.

The moulds are then fed to a curing line. If hot cement is used, oven curing can be eliminated. Oven curing generally requires about 6 hours to produce a hardened shell for glass fibre reinforced cement tops and bottoms; curing time for hot cement is generally 50% less.

Next, with the hardened bottom portion of the shell still supported by its mould, a flowable, foamable rigid urethane polymer composition is poured into the open shell and the top is then set in place before substantial foaming begins. The top can be removed from its mould at this point or it can continue to be supported by the mould. With the top in place, the mould supported assembly is then held under pressure while the urethane polymer foams and sets. This can be accomplished using a hydraulic plated press or other restraint device.

After the urethane polymer foam sets, filling the shell and providing an overall rigid interfacial adhesive interlock between the rigid foam core and the interior of the shell, the panel is removed from the bottom mould and the top mould (if not previously removed).

After removing the mould or moulds, the composite panel is ready for use or can have a surface finish applied. Preferably, the surfaces of the panel have applied thereto, using electrostatic coating techniques for example, a sealer, such as a polyester type of sealer. While the panel itself is substantially water-proof, the application of a sealer insures that the panel will maintain its water proofness. If desired, in addition to or in place of a sealer, the panel can be painted, stained or other types of coatings can be applied, for example, to provide for easy removal of graffiti. It has also been found that a sealer, when applied in a thick coating, can also be used to adhere aggregate to a surface of the panel to provide a surface finish.

In the embodiment of Figure 1, the juncture between the open shell 12 and the cover or top 12' can be formed at roughly 45° angles as shown, or any combination of right-angles can be employed, including a set-in or overlapping configuration. where the two members 12 and 12' come together as shown in Figure 1, the mating edges can be formed to leave a slight gap so that foaming polymer can enter therein during the foaming operation.

Many modifications can be made in the composite building modules of the invention without departing from the spirit and scope thereof. For example, the rigid foam core 14 can be reinforced utilizing woven or nonwoven screen and mesh layers made of synthetic fibres or metals and prestressing techniques can be employed if desired. As mentioned previously, one or more exterior surfaces of the shell 12 can be provided with any desired - 14 finish, texture or design or can be embedded with inorganic aggregates such as gravel, broken stone, marble chips and the like. As for surface design and texture, the exterior of the shell 12 will conform to the finish of the mould surface to achieve desired effects, for example, a wood grain appearance and the like. The shell 12 can also be formed with moulded-in mounting or building clips and/or grooves.

As mentioned previously, the composite building module of the invention can be used and installed in the same manner as conventional building modules such as curtain-wall panels but with a great reduction in weight (and simplified installation procedures). Because of the greatly improved insulating and water vapour barrier properties of the modules of the invention, no further steps have to be taken to ensure these properties as is the case with conventional building modules.

In roof deck installations or curtain-wall installations a room temperature curing elastomer such as a silicone elastomer can be used for edge-to-edge bonding between adjacent modules and the entire installation can be provided with an overcoating of a suitable elastomer. This provides for a shock resistant installation which can also compensate for later movement of a structure, for example, as a building settles after construction.

Because the composite building modules of the invention are extremely light as compared to conventional monolithic cast concrete modules, fewer structural members are necessary for supporting, for example, a curtain-wall made of panels of the present invention and a roof deck made of panels of the present invention. - 15 For example, a 4’ x 8’ precast concrete module weighs from 1400-1600 lbs., whereas a comparable composite module made according to the invention weighs only 100-150 lbs. depending on the thickness of the shell 12. Thus, great savings can be realized in not only installation procedures but also in the strength requirements for the supporting superstructure.

In addition to the uses illustrated in Figure 3 of the drawing, the composite module in the invention can be formed into insulated pipes ahd conduits, railroad ties, modular walls and even load-bearing modular panels which can incorporate conduits for utilities, window frames, door .frames and the like. It should also be noted that the composite building panel of the invention is buoyant; because of the rigid foam core 14 which properly can be . utilized to advantage in the construction of floating docks and wharfs as well as offshore drilling platforms.

It is known that a 1/8 inch or 1/4 inch coating of a hardened mixture of cement and glass fibres gives accept20 able fire ratings to the underlying coated base. Thus, in a preferred embodiment of the invention, rigid urethane polymer foams are provided with acceptable fire ratings by forming a laminate of a layer of rigid urethane polymer foam with an outer covering layer made of a hardened mixture of cement and glass fibres.

Foamable urethane compositions forming rigid urethane polymer foams are commercially available in a wide range of chemical and physical properties. Such compositions generally contain an isocyanate component containing reactive isocyanate groups, a polyol component containing one or more polyols, catalytic agents and preferably a 2359 - 16 flame or fire resistant agent suoh as trichloromonofluoro methane. Typical properties of rigid urethane polymer foams available commercially are set forth in the following table:ui O m o -o m O o o ra rd k h in co rd CI cn id fi 1 I 1 l 1 ra ra ό •H o o o O O rd * ra ft 0 w in m o m O ♦ rd ω S ft Cl m m co cn u ft fi rd •H H 43 £ O O ra a £ ft o to ft id 0 0 H fi ft ϋ Ch. ra ft in O m ft Id 0» O O Cl 00 Γ*· •H ra tn k fi in c- rd rd Cl is ft fi ra ra ra I I I 1 1 •H •H ra ra k •ri O O in m in ft 0 •H ft ft ra ci m si· Cl ft fi ft w CQ 0 rd g> Ό k fi 0 QJ rd •H k Q 0 fi ft 0 ra k k 0 k ft ra O 0 k 1 ft £3 ra rd id ra (j > Cl o o fi ra o •rt kO O O O O o ra ra ra ft ra rd O O o O o fi £ ra ra ra O m o Cl o 0 o ra ra ra fi fl Cl co 10 rd d •rl ra fi k H I l 1 ft >1 0 id ft fi β O O O O o •rl ft 0 43 c2 Ό -rl 5 o o o O o ra k ft Q o w ra sp co in CO o 0 ft ra M U S ft < rd m m £ fi cd 43 O 0 fi o «. id 0 ra •r| ra k ra 0 fi id ra •rl ra rd S ra rd ft (d fi > Cl ft rd Ό r-i •rl kO in O o ra ra Q id m ft rd O in 00 in o k Q £ ϋ ra ft kO Oi rd cn kD fi •r| ra O' fl 1 I 1 ·» tn k fi o in o O o ra ra fi ft ra £ Cl cn m O o rd rd •H g k -H ft rd Cl ft ft. *G 0 ft ra ra . (d ra rd a M ft< § rd a •H fi 0 ft ft ? ra ra ra ft rd •H ft ra Cl id fi 0 • Cl o . ft 0 ft ft kO O • *H •H £ ft rd O m O o fi ft 0 t>f * Cl cn sf rd CQ td □ ft fi a I 1 1 k •HO in rd r-f kO rd 0 • w \ ε • • • • • ft ό fi · ft •ft CI cn sp k •H ra ft ra 0 ft fl rd a O ft fi 0) ra ra k ft Patent Specification No. 1+^.3 S3 from which the fi J •Η Ό Ό ό 0) -H 4 rd «0 ra πί ? fi o Ή ft d □ •rl fi id Ό O W ft QJ S' id o rd in rd

Claims (6)

1. CLAIMS :1. A composite building module comprising a rigid foam core, encased in an enclosed shell made from a hardened mixture of cement and fibres, said core being 5 formed by foaming a foamable polymer composition in a shell having one open side followed by forming a cover for the open side over the core to close the shell with the core encased therein, said core being adhesively interlocked via the in situ foaming with the shell. 10

2. A process for making a composite building module which comprises forming a supported shell having one open side from a hardened mixture of cement and fibres, introducing a foamable polymer into said open shell thereby filling the shell with a polymer foam, 15 thereafter applying a cover for the open side over the foamed core to close the shell with the core encased therein using a hardenable mixture of cement and fibres and curing said cover.

3. A process according to claim 2 wherein the 20 mixture applied to form the cover is applied down over the side walls of the shell.

4. A process according to claim 3 wherein the open shell is formed by applying fibres and then wet cement to the interior of a mould followed by vibrating to 25 distribute the fibres in the wet cement.

5. A process according to claim 2 substantially as herein described.

6. A composite building module according to claim 1 substantially as herein described with reference to and as 30 shown in the accompanying drawings.