Abstract:
This invention relates to a structural cementitious panel (SCP) panel able to resist lateral forces imposed by high wind and earthquake loads in regions where they are required by building codes. These panels may be used for shear walls, flooring or roofing or other locations where shear panels are used in residential or commercial construction. The panels employ one or more layers of a continuous phase resulting from the curing of an aqueous mixture of inorganic binder reinforced with glass fibers and containing lightweight filler particles. One or more reinforcement members, such as mesh or plate sheets, are bonded to at least one surface of the panel to provide a completed panel that can breathe and has weather resistant characteristics to be capable of sustaining exposure to the elements during construction, without damage.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This claims the benefit under 35 USC 119 of U.S. provisional patent application No. 60/754,272 filed Dec. 29, 2005, incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to shear panels that are applied to framing in residential and other types of light construction. More particularly, the invention relates to panels that are able to resist lateral forces imposed by high wind and earthquake loads in regions where they are required by building codes. Such panels, commonly known as shear walls or diaphragms, must demonstrate shear resistance as shown in recognized tests, such as ASTM E72. These panels may also be used for flooring or roofing or other locations where shear panels are used in residential or commercial construction. The shear panels include one or more reinforcement members bonded to a structural cementitious panel (SCP) to provide a completed panel that can breathe and has weather resistant characteristics to be capable of sustaining exposure to the elements during construction, without damage. The SCP material (continuous phase) of the SCP panel is made from a mixture of inorganic binder and lightweight fillers. 
     BACKGROUND OF THE INVENTION 
     Interior residential and light commercial wall and flooring systems commonly include plywood or oriented strand board (OSB) nailed to a wooden frame or mechanically fastened to a metal frame. OSB consists of pieces of wood glued together. Regardless of whether the frame of a building is constructed from wood and/or steel, such frame structures are commonly subjected to a variety of forces. Among the most significant of such forces are gravity, wind, and seismic forces. Gravity is a vertically acting force while wind and seismic forces are primarily laterally acting. Not all sheathing panels are capable of resisting such forces, nor are they very resilient, and some will fail, particularly at points where the panel is fastened to the framing. Where it is necessary to demonstrate shear resistance, the sheathing panels are measured to determine the load which the panel can resist within the allowed deflection without failure. 
     The shear rating is generally based on testing of three identical 8×8 feet (2.44×2.44 m) assemblies, i.e., panels fastened to framing. One edge is fixed in place while a lateral force is applied to a free end of the assembly until the load is no longer carried and the assembly fails. The measured shear strength will vary, depending upon the thickness of the panel and the size and spacing of the nails or mechanical fasteners used in the assembly. The measured strength will vary as the nail or mechanical fastener size and spacing is changed, as the ASTM E72 test provides. This ultimate strength will be reduced by a safety factor, e.g., typically a factor of two to three, to set the design shear strength for the panel. 
     As the thickness of the board affects its physical and mechanical properties, e.g., weight, load carrying capacity, racking strength and the like, the desired properties vary according to the thickness of the board. 
     U.S. Pat. No. 6,620,487 to Tonyan et al., incorporated herein by reference in its entirety, discloses a reinforced, lightweight, dimensionally stable structural cement panel (SCP) capable of resisting shear loads when fastened to framing equal to or exceeding shear loads provided by plywood or oriented strand board panels. The panels employ a core of a continuous phase resulting from the curing of an aqueous mixture of calcium sulfate alpha hemihydrate, hydraulic cement, an active pozzolan and lime, the continuous phase being reinforced with alkali-resistant glass fibers and containing ceramic microspheres, or a blend of ceramic and polymer microspheres, or being formed from an aqueous mixture having a weight ratio of water-to-reactive powder of 0.6/1 to 0.7/1 or a combination thereof. At least one outer surface of the panels may include a cured continuous phase reinforced with glass fibers and containing sufficient polymer spheres to improve nailability or made with a water-to-reactive powders ratio to provide an effect similar to polymer spheres, or a combination thereof. 
     U.S. Pat. No. 6,241,815 to Bonen, incorporated herein by reference in its entirety, also discloses formulations useful for SCP panels. 
     One form of wallboard structure purportedly for metal construction applications is disclosed in U.S. Pat. No. 5,768,841 to Swartz et al. That wallboard structure has a metal sheet attached to an entire side of a gypsum panel with an adhesive. Another wallboard panel is disclosed in U.S. Pat. No. 6,412,247 to Menchetti et al. The International Building Code in its “Steel” section also references the use of shear walls utilizing panel type members, i.e., drywall, steel plates and plywood, etc. 
     US patent application publication no. 2005/0086905 A1 to Ralph et al. discloses shear wall panels and methods of manufacturing shear wall panels. Various embodiments comprise wallboard material employed with a sheet stiffener in the form of a plate to form a wall panel that may be used in applications wherein shear panels are desired. 
     SUMMARY OF THE INVENTION 
     The present invention relates to one or more reinforcement members bonded to an SCP panel to provide a completed panel that can breathe and has weather resistant characteristics to be capable of sustaining exposure to the elements during construction, without damage. The SCP material (continuous phase) of the SCP panel is made from a mixture of inorganic binder and lightweight fillers. 
     In particular, the present invention relates to a panel for resisting shear loads when fastened to framing, comprising: a panel of a continuous phase resulting from the curing of an aqueous mixture comprising, on a dry basis, 35 to 70 weight % reactive powder, 20 to 50 weight % lightweight filler, and 5 to 20 weight % glass fibers, the continuous phase being reinforced with glass fibers and containing the lightweight filler particles, the lightweight filler particles having a particle specific gravity of from 0.02 to 1.00 and an average particle size of about 10 to 500 microns (micrometers); and at least one reinforcing member selected from the group consisting of plate and a mesh sheet attached to a first surface of the continuous phase panel, wherein the at least one reinforcing member covers 5 to 90%, typically 10 to 80%, of the first surface of the continuous phase panel. 
     Typically, a high strength adhesive such as an epoxy or urethane is applied to a reinforcement member or to indentations on the embossed side of a weather durable SCP panel such sheet of mesh or metal. The reinforcement member is then placed into the indentations on the embossed side of a weather durable SCP panel and then held in a press until the adhesive has cured sufficiently to permit handling the panel without debonding. The finished panel can then be placed on steel or wood framing and attached with either screws or nails. Shear capacity will be determined by the gage of the laminated sheet, size spacing of the fasteners, and the gage and size of the framing members. Typically about 5 to 90%, typically about 10 to 80%, or about 20 to 50% of the embossed side is covered with one or more reinforcement members. If desired the embossing can be omitted such that the reinforcement members protrude from the surface of the SCP panel. 
     In a first embodiment, a fiber reinforced SCP panel is reinforced with horizontal metal strips 8-12 inches wide laminated along the length of the panel at the edges and mid point of the panel. This reduces the weight of the panel compared to a panel covered with a full sheet of metal. At 12 inches wide the panel typically has about half the steel of a fully laminated panel. The strips allow the panel to breathe and the spacing allows the panel to be adequately supported between the strips. The shear capacity is a function of the gage of metal and width of the strips. 
     In a second embodiment, the edges of the SCP panel are stiffened by placing metal along the SCP panel edges and bending the metal, e.g., ⅜ inch of metal edge, approximately 90 degrees to form a shallow tray to protect the edges of the SCP panel and add to the lateral fastener pullout strength to resist tear out along edges when the panel is loaded in shear. The term “tear out” means where the fastener tears out a portion of the SCP panel as the panel is racked. 
     In another embodiment, a reinforced SCP panel is reinforced with diagonal metal plates at the corners to carry the shear and rectangular plates in the field to laterally support the panel against bending out of plane when attached to framing. This embodiment also allows the panel to breathe and reduces the weight of the steel. This embodiment typically has about ⅓ the amount of steel as a fully laminated sheet. 
     The reinforcement members are typically metal, polymer or mesh. Typical metal sheets are about 0.02 to about 0.07 inches (about 0.05 to about 0.2 cm) thick. The metal is typically steel or aluminum. For example, steel sheets about 25 to 14 gauge, e.g., 22 gauge. The metal can be replaced by one or more about 1/32 to ¼ inch (about 0.08 to about 0.6 cm) thick sheets of polymer, e.g., thermoplastic polymer or thermosetting polymer, or mesh, e.g. fiber glass mesh or carbon fiber mesh. 
     The present invention also relates to floor or wall systems for residential and light commercial construction including a wooden or metal frame and the reinforced SCP shear panels. Employing a metal frame provides a fully non-combustible system in which all elements pass ASTM E-136. For example, the system may include the reinforced SCP panels employed with a metal framing system employing any standard light-gauge steel C-channels, U-channels, 1-beams, square tubing, corrugated metal sheet, and light-gauge prefabricated building sections, such as floor trusses or open web bar joists. The composite SCP panel may be fastened to framing members with either pneumatically driven nails or conventional self-drilling screws. 
     A wall of reinforced SCP shear panel may have a higher specific racking strength in a shear wall compared to a reinforced concrete masonry shear wall. Specific racking strength is the ultimate racking strength (in pounds per lineal foot) divided by the weight of the wall assembly (in pounds per lineal foot) for a constant wall height. For a given racking strength the present inventive wall is lighter within a practical range of racking strengths than the respective masonry wall of the same racking strength. 
     The present system having a shear diaphragm on light gauge cold rolled metal frame also is typically water durable. Preferably when testing the system with the SCP panels laid oriented horizontally, the horizontal shear diaphragm load carrying capacity of a system of the present invention will not be lessened by more than 25% (more preferably will not be lessened by more than 20%) when exposed to water in a test wherein a 2 inch head of water is maintained over ¾ inch thick reinforced SCP panels fastened on a 10 foot by 20 foot metal frame for a period of 24 hours. In this test, the 2 inch head is maintained by checking, and replenishing water, at 15 minute intervals. 
     Preferably the system of the present invention will not absorb more than 0.7 pounds per square foot of water when exposed to water in a test wherein a 2 inch head of water is maintained over ¾ inch thick reinforced SCP panels fastened on a 10 foot by 20 foot metal frame for a period of 24 hours. In this test, the 2 inch head is maintained by checking, and replenishing water, at 15 minute intervals. 
     Also, the system of the present invention resists swelling due to moisture. Preferably, in the system of the present invention a system of a oriented horizontally 10 foot wide by 20 foot long by ¾ inch thick diaphragm of the reinforced SCP panels attached to a 10 foot by 20 foot metal frame will not swell more than 5% when exposed to a 2 inch head of water maintained over the SCP panels fastened on the metal frame for a period of 24 hours. In this test, the 2 inch head is maintained by checking, and replenishing water, at 15 minute intervals. 
     Also, the system of the present invention leads to a mold and mildew resistant floor, wall or roof system. Preferably every component of the system of the present invention meets ASTM G-21 in which the system achieves approximately a rating of 1 and meets ASTM D-3273 in which the system achieves approximately a rating of 10. Preferably the system of the present invention supports substantially zero bacteria growth when clean. 
     A potential advantage of the present system is that, due to its high strength it is better able to provide an earthquake resistant structure. 
     As the thickness of the board affects its physical and mechanical properties, e.g., weight, load carrying capacity, racking strength and the like, the desired properties vary according to the thickness of the board. Thus, for example, the desired properties which a shear rated panel with a nominal thickness of 0.75 inches (19.1 mm) should meet include the following. 
     A 4×8 ft, ¾ inch thick panel (1.22×2.44 m, 19.1 mm thick) typically weighs no more than 156 lbs (71 kg) and preferably no more than 144 lbs (65.5 kg). Thinner panels are proportionally lighter. 
     The present invention provides a method of making the reinforced SCP panel. The present invention provides a method of making systems comprising placing the reinforced SCP panel on one or both sides of metal framing members. The reinforced SCP panels may float on the framing members, for example, joists, or be connected to the framing members mechanically or by adhesive. Connecting the reinforced SCP panels directly or indirectly to the metal framing members may achieve a composite action such that the metal framing and panels work together to carry greater loads. 
     The present invention also encompasses a non-combustible building system, such as a floor, wall or roof system, including a reinforced SCP panel of the present invention attached to one or both sides of a metal frame to increase the shear capacity of the framed wall. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a first embodiment of a reinforced structural cementitious panel (SCP) panel of the present invention employing strips of reinforcing sheets inserted in indentations on the SCP material of the panel. 
         FIG. 2  is a cross-sectional view along view II-II of the panel of  FIG. 1 . 
         FIG. 3  is a top view of a second embodiment of a reinforced SCP panel of the present invention employing strips of reinforcing sheets, including strips which wrap around opposed edges of the panel. 
         FIG. 4  is a cross-sectional view along view IV-IV of the panel of  FIG. 3 . 
         FIG. 5  is a top view of a third embodiment of a reinforced SCP panel of the present invention wherein the reinforcement strips protrude from a surface of the panel. 
         FIG. 6  is a cross-sectional view along view VI-VI of the panel of  FIG. 5 . 
         FIG. 7  is a top view of a fourth embodiment of a reinforced SCP panel of the present invention including reinforcing strips which wrap around opposed sidewalls of the panel. 
         FIG. 8  is a cross-sectional view along view VIII-VIII of the panel of  FIG. 7 . 
         FIG. 9  is a perspective view of a fifth embodiment of a reinforced SCP panel of the present invention including reinforcing mesh which wrap around opposed walls of the panel. 
         FIG. 10  is a top view of a sixth embodiment of a reinforced SCP panel of the present invention including reinforcing corner pieces and separate optional reinforcing strips. 
         FIG. 11  is a cross-sectional view along view XI-XI of the panel of  FIG. 10 . 
         FIG. 12  is a cross-sectional view along view XII-XII of the panel of  FIG. 10 . 
         FIG. 13  is a top view of a seventh embodiment of a reinforced SCP panel of the present invention including reinforcing strips and separate reinforcing corner pieces. Optionally, two of the reinforcing strips contact the corner pieces. 
         FIG. 14  is a cross-sectional view along view XIV-XIV of the panel of  FIG. 13 . 
         FIG. 15  is a cross-sectional view along view XV-XV of the panel of  FIG. 13 . 
         FIG. 16  is a top view of an eighth embodiment of a reinforced SCP panel of the present invention employing a one piece reinforced border on one of its surfaces. 
         FIG. 17  is a cross-sectional view along view XVII-XVII of the panel of  FIG. 16 . 
         FIG. 18  is a top view of a ninth embodiment of a reinforced SCP panel of the present invention employing a multi-piece reinforced border on one of its surfaces. 
         FIG. 19  is a top view of a tenth embodiment of a reinforced SCP panel of the present invention employing a perforated panel. 
         FIG. 20  is a cross-sectional view along view XX-XX of the panel of  FIG. 19 . 
         FIG. 21  is a perspective view of the panel of  FIG. 19 . 
         FIG. 22  is a perspective view of a portion of an eleventh embodiment of a reinforced SCP panel of the present invention employing a panel with small perforations. 
         FIG. 23  is a top view of a portion of a twelfth embodiment of a reinforced SCP panel of the present invention employing a panel with small perforations. 
         FIG. 24  is a cross-sectional view along view XXIV-XXIV of the panel of  FIG. 23 . 
         FIG. 25  is a top view of a portion of a thirteenth embodiment of a reinforced SCP panel of the present invention. 
         FIG. 26  is a cross-sectional view along view XXVI-XXVI of the panel of  FIG. 25 . 
         FIG. 27  is a top view of a portion of a fourteenth embodiment of a reinforced SCP panel of the present invention. 
         FIG. 28  is a cross-sectional view along view XXVIII-XXVIII of the panel of  FIG. 27 . 
         FIG. 29  is a side view of a multi-layer SCP panel of the present invention with the reinforcement omitted for clarity. 
         FIG. 30  is a schematic side view of a metal frame wall suitable for employing with a reinforced structural cementitious panel (SCP) panel of the present invention. 
         FIG. 31  is an elevation view of an apparatus which is suitable for making the SCP panel of the present invention, except for a downstream embossing station and reinforcement attaching station. 
         FIG. 32  is a perspective view of a slurry feed station of the type used in the present process. 
         FIG. 33  is a fragmentary overhead plan view of an embedment device suitable for use with the present process to embed lightweight filler. 
         FIG. 34  shows ASTM E72 Racking data of five 8 foot×8 foot (2.16 m×2.16 mm) samples with SCP installed horizontally on 16 gauge 3.624 steel studs at 16 inches on center with fastener layout of 6″ (15.2 cm) on center on the perimeter and 12″ (30.4 cm) in the field. 
         FIG. 35  is a perspective view of a typical metal floor frame  160  suitable for use with the reinforced SCP panels of the present invention. 
         FIG. 36  is a fragmentary schematic vertical section of a single-layer SCP panel  162  supported on metal frame of  FIG. 35  in a system of the present invention. 
         FIG. 37  is a perspective view of SCP panels of  FIG. 36  supported on a corrugated sheet in the non-combustible flooring system of the present invention. 
         FIG. 38  shows a perspective view of a portion of the embodiment of  FIG. 37  wherein SCP panel is attached to corrugated sheet with metal screws. 
         FIG. 39  shows an embodiment of a roofing system using the reinforced SCP panels of the present invention. 
         FIG. 40  shows another embodiment of a roofing system using the reinforced SCP panels of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention may employ single layer or multi-layer SCP panels reinforced with reinforcement members such as sheets of metal, polymer or mesh placed on the panel surface. The reinforcement members are typically metal, polymer or mesh, e.g. fiber glass mesh or carbon fiber mesh. 
     Typical SCP panel material (discussed in more detail elsewhere in this specification) is made from a mixture of water and inorganic binder (examples—gypsum-cement, Portland cement or other hydraulic cements) with the selected lightweight fillers (examples glass fibers, hollow glass microspheres, hollow ceramic microspheres and/or perlite uniformly), and superplasticizer/high-range water reducing admixtures (examples—polynapthalene sulfonates, poly acrylates, etc.) distributed throughout the mixture. Other additives such as accelerating and retarding admixtures, viscosity control additives may optionally be added to the mixture to meet the demands of the manufacturing process involved. The glass fibers can be used alone or in combination with other types of non-combustible fibers such as steel fibers. This results in panels of the present invention which comprise inorganic binder having the selected lightweight fillers distributed throughout the full thickness of the panel. 
     In the multi-layer SCP panel the layers may be the same or different. For example, the SCP panel may have an inner layer of a continuous phase and at least one outer layer of a continuous phase on each opposed side of the inner layer, wherein at least one outer layer on each opposed side of the inner layer has a higher percentage of glass fibers than the inner layer. This has the ability to stiffen, strengthen and toughen the panel. In another embodiment, a multi-layer panel structure may be created to contain at least one outer layer having improved nailability and cutability by using a higher water-to-reactive powder (defined below) ratio in making the outer layer(s) relative to the core of the panel. A small thickness of the skin coupled with a small dosage of polymer content may improve the nailability without necessarily failing the non-combustibility test. Of course, high dosages of polymer content would lead to failure of the product in the non-combustibility test. 
     Calcium Sulfate Hemihydrate 
     Calcium sulfate hemihydrate, which may be used in panels of the invention, is made from gypsum ore, a naturally occurring mineral, (calcium sulfate dihydrate CaSO 4 .2H 2 O). Unless otherwise indicated, “gypsum” will refer to the dihydrate form of calcium sulfate. After being mined, the raw gypsum is thermally processed to form a settable calcium sulfate, which may be anhydrous, but more typically is the hemihydrate, CaSO 4 .½H 2 O. For the familiar end uses, the settable calcium sulfate reacts with water to solidify by forming the dihydrate (gypsum). The hemihydrate has two recognized morphologies, termed alpha hemihydrate and beta hemihydrate. These are selected for various applications based on their physical properties and cost. Both forms react with water to form the dihydrate of calcium sulfate. Upon hydration, alpha hemihydrate is characterized by giving rise to rectangular-sided crystals of gypsum, while beta hemihydrate is characterized by hydrating to produce needle-shaped crystals of gypsum, typically with large aspect ratio. In the present invention either or both of the alpha or beta forms may be used depending on the mechanical performance desired. The beta hemihydrate forms less dense microstructures and is preferred for low density products. The alpha hemihydrate forms more dense microstructures having higher strength and density than those formed by the beta hemihydrate. Thus, the alpha hemihydrate could be substituted for beta hemihydrate to increase strength and density or they could be combined to adjust the properties. 
     A typical embodiment for the inorganic binder used to make panels of the present invention comprises hydraulic cement such as Portland cement, high alumina cement, pozzolan-blended Portland cement, or mixtures thereof. 
     Another typical embodiment for the inorganic binder used to make panels of the present invention comprises a blend containing calcium sulfate alpha hemihydrate, hydraulic cement, pozzolan, and lime. 
     Hydraulic Cement 
     ASTM defines “hydraulic cement” as follows: a cement that sets and hardens by chemical interaction with water and is capable of doing so under water. There are several types of hydraulic cements that are used in the construction and building industries. Examples of hydraulic cements include Portland cement, slag cements such as blast-furnace slag cement and super-sulfated cements, calcium sulfoaluminate cement, high-alumina cement, expansive cements, white cement, and rapid setting and hardening cements. While calcium sulfate hemihydrate does set and harden by chemical interaction with water, it is not included within the broad definition of hydraulic cements in the context of this invention. All of the aforementioned hydraulic cements can be used to make the panels of the invention. 
     The most popular and widely used family of closely related hydraulic cements is known as Portland cement. ASTM defines “Portland cement” as a hydraulic cement produced by pulverizing clinker consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an interground addition. To manufacture Portland cement, an intimate mixture of limestone, argallicious rocks and clay is ignited in a kiln to produce the clinker, which is then further processed. As a result, the following four main phases of Portland cement are produced: tricalcium silicate (3CaO.SiO 2 , also referred to as C 3 S), dicalcium silicate (2CaO.SiO 2 , called C 2 S), tricalcium aluminate (3CaO.Al 2 O 3  or C 3 A), and tetracalcium aluminoferrite (4CaO.Al 2 O 3 .Fe 2 O 3  or C 4 AF). Other compounds present in minor amounts in Portland cement include calcium sulfate and other double salts of alkaline sulfates, calcium oxide, and magnesium oxide. Of the various recognized classes of Portland cement, Type III Portland cement (ASTM classification) is preferred for making the panels of the invention, because of its fineness it has been found to provide greater strength. The other recognized classes of hydraulic cements including slag cements such as blast-furnace slag cement and super-sulfated cements, calcium sulfoaluminate cement, high-alumina cement, expansive cements, white cement, rapidly setting and hardening cements such as regulated set cement and VHE cement, and the other Portland cement types can also be successfully used to make the panels of the present invention. The slag cements and the calcium sulfoaluminate cement have low alkalinity and are also suitable to make the panels of the present invention. 
     Fibers 
     Glass fibers are commonly used as insulating material, but they have also been used as reinforcing materials with various matrices. The fibers themselves provide tensile strength to materials that may otherwise be subject to brittle failure. The fibers may break when loaded, but the usual mode of failure of composites containing glass fibers occurs from degradation and failure of the bond between the fibers and the continuous phase material. Thus, such bonds are important if the reinforcing fibers are to retain the ability to increase ductility and strengthen the composite over time. It has been found that glass fiber reinforced cements do lose strength as time passes, which has been attributed to attack on the glass by the lime which is produced when cement is cured. One possible way to overcome such attack is to cover the glass fibers with a protective layer, such as a polymer layer. In general, such protective layers may resist attack by lime, but it has been found that the strength is reduced in panels of the invention and, thus, protective layers are not preferred. A more expensive way to limit lime attack is to use special alkali-resistant glass fibers (AR glass fibers), such as Nippon Electric Glass (NEG) 350Y. Such fibers have been found to provide superior bonding strength to the matrix and are, thus, preferred for panels of the invention. The glass fibers are monofilaments that have a diameter from about 5 to 25 microns (micrometers) and typically about 10 to 15 microns (micrometers). The filaments generally are combined into 100 filament strands, which may be bundled into rovings containing about 50 strands. The strands or rovings will generally be chopped into suitable filaments and bundles of filaments, for example, about 0.25 to 3 inches (6.3 to 76 mm) long, typically 1 to 2 inches (25 to 50 mm). 
     It is also possible to include other non-combustible fibers in the panels of the invention, for example, steel fibers are also potential additives. 
     Pozzolanic Materials 
     As has been mentioned, most Portland and other hydraulic cements produce lime during hydration (curing). It is desirable to react the lime to reduce attack on glass fibers. It is also known that when calcium sulfate hemihydrate is present, it reacts with tricalcium aluminate in the cement to form ettringite, which can result in undesirable cracking of the cured product. This is often referred to in the art as “sulfate attack.” Such reactions may be prevented by adding “pozzolanic” materials, which are defined in ASTM C618-97 as “ . . . siliceous or siliceous and aluminous materials which in themselves possess little or no cementitious value, but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties.” One often used pozzolanic material is silica fume, a finely divided amorphous silica which is the product of silicon metal and ferro-silicon alloy manufacture. Characteristically, it has a high silica content and a low alumina content. Various natural and man-made materials have been referred to as having pozzolanic properties, including pumice, perlite, diatomaceous earth, tuff, trass, metakaolin, microsilica, ground granulated blast furnace slag, and fly ash. While silica fume is a particularly convenient pozzolan for use in the panels of the invention, other pozzolanic materials may be used. In contrast to silica fume, metakaolin, ground granulated blast furnace slag, and pulverized fly ash have a much lower silica content and large amounts of alumina, but can be effective pozzolanic materials. When silica fume is used, it will constitute about 5 to 20 wt. %, preferably 10 to 15 wt. %, of the reactive powders (i.e., hydraulic cement, calcium sulfate alpha hemihydrate, silica fume, and lime). If other pozzolans are substituted, the amounts used will be chosen to provide chemical performance similar to silica fume. 
     Lightweight Fillers/Microspheres 
     The lightweight panels employed in systems of the present invention typically have a density of 65 to 90 pounds per cubic foot, preferably 65 to 85 pounds per cubic foot, more preferably 72 to 80 pounds per cubic foot. In contrast, typical Portland cement based panels without wood fiber will have densities in the 95 to 110 pcf range, while the Portland Cement based panels with wood fibers will be about the same as SCP (about 65 to 85 pcf). 
     To assist in achieving these low densities the panels are provided with lightweight filler particles. Such particles typically have an average diameter (average particle size) of about 10 to 500 microns (micrometers). More typically they have a mean particle diameter (mean particle size) from 50 to 250 microns (micrometers) and/or fall within a particle diameter (size) range of 10 to 500 microns. They also typically have a particle density (specific gravity) in the range from 0.02 to 1.00. Microspheres or other lightweight filler particles serve an important purpose in the panels of the invention, which would otherwise be heavier than is desirable for building panels. Used as lightweight fillers, the microspheres help to lower the average density of the product. When the microspheres are hollow, they are sometimes referred to as microballoons. 
     When the microspheres are hollow, they are sometimes referred to as microballoons. 
     The microspheres are either non-combustible themselves or, if combustible, added in sufficiently small amounts to not make the SCP panel combustible. Typical lightweight fillers for including in mixtures employed to make panels of the present invention are selected from the group consisting of ceramic microspheres, polymer microspheres, perlite, glass microspheres, and/or fly ash cenospheres. 
     Ceramic microspheres can be manufactured from a variety of materials and using different manufacturing processes. Although a variety of ceramic microspheres can be utilized as a filler component in the panels of the invention, the preferred ceramic microspheres of the invention are produced as a coal combustion by-product and are a component of the fly ash found at coal fired utilities, for example, EXTENDOSPHERES-SG made by Kish Company Inc., Mentor, Ohio or FILLITE® Brand ceramic microspheres made by Trelleborg Fillite Inc., Norcross, Ga. USA. The chemistry of the preferred ceramic microspheres of the invention is predominantly silica (SiO 2 ) in the range of about 50 to 75 wt. % and alumina (Al 2 O 3 ) in the range of about 15 to 40 wt. %, with up to 35 wt. % of other materials. The preferred ceramic microspheres of the invention are hollow spherical particles with diameters in the range of 10 to 500 microns (micrometers), a shell thickness typically about 10% of the sphere diameter, and a particle density preferably about 0.50 to 0.80 g/mL. The crushing strength of the preferred ceramic microspheres of the invention is greater than 1500 psi (10.3 MPa) and is preferably greater than 2500 psi (17.2 MPa). 
     Preference for ceramic microspheres in the panels of the invention primarily stems from the fact that they are about three to ten times stronger than most synthetic glass microspheres. In addition, the preferred ceramic microspheres of invention are thermally stable and provide enhanced dimensional stability to the panel of invention. Ceramic microspheres find use in an array of other applications such as adhesives, sealants, caulks, roofing compounds, PVC flooring, paints, industrial coatings, and high temperature-resistant plastic composites. Although they are preferred, it should be understood that it is not essential that the microspheres be hollow and spherical, since it is the particle density and compressive strength which provide the panel of the invention with its low weight and important physical properties. Alternatively, porous irregular particles may be substituted, provided that the resulting panels meet the desired performance. 
     The polymer microspheres, if present, are typically hollow spheres with a shell made of polymeric materials such as polyacrylonitrile, polymethacrylonitrile, polyvinyl chloride or polyvinylidine chloride, or mixtures thereof. The shell may enclose a gas used to expand the polymeric shell during manufacture. The outer surface of the polymer microspheres may have some type of an inert coating such as calcium carbonate, titanium oxides, mica, silica, and talc. The polymer microspheres have a particle density preferably about 0.02 to 0.15 g/mL and have diameters in the range 10 to 350 microns (micrometers). The presence of polymer microspheres may facilitate simultaneous attainment of low panel density and enhanced cutability and nailability. 
     Other lightweight fillers, for example glass microspheres, perlite or hollow alumino-silicate cenospheres or microspheres derived from fly ash, are also suitable for including in mixtures in combination with or in place of ceramic microspheres employed to make panels of the present invention. 
     The glass microspheres typically are made of alkali resistant glass materials and may be hollow. Typical glass microspheres are available from GYPTEK INC., Suite 135, 16 Midlake Blvd SE, Calgary, AB, T2X 2X7, CANADA. 
     In a first embodiment of the invention, only ceramic microspheres are used throughout the full thickness of the panel. The panel typically contains about 35 to 42 weight % of ceramic microspheres uniformly distributed throughout the thickness of the panel. 
     In a second embodiment of the invention, a blend of lightweight ceramic and glass microspheres is used throughout the full thickness of the panel. The volume fraction of the glass microspheres in the panel of the second embodiment of the invention will typically be in the range of 0 to 15% of the total volume of the dry ingredients, where the dry ingredients of the composition are the reactive powders (examples of reactive powders: hydraulic cement only; blend of hydraulic cement and pozzolan; or blend of hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), ceramic microspheres, polymer microspheres, and alkali-resistant glass fibers. A typical aqueous mixture has a ratio of water-to-reactive powders from greater than 0.3/1 to 0.7/1. 
     As mentioned above, if desired the panel may have a single layer or multiple layers of SCP material. Typically, the panel is made by a process which applies multiple layers which, depending upon how the layers are applied and cured as well as whether the layers have the same or different compositions, may or may not in the final panel product retain distinct layers.  FIG. 29  shows a multi-layer structure of a panel  101  having layers  102 ,  104 ,  106  and  108 . In the multi-layer structure the composition of the layers may be the same or different. The typical thickness of the layer(s) ranges between about 1/32 to 1.0 inches (about 0.75 to 25.4 mm). Where only one outer layer is used, it typically will be less than ⅜ of the total panel thickness. 
     Typical Configurations of Reinforced SCP Panels of the Present Invention 
       FIG. 1  is a top view of a first embodiment of a metal reinforced structural cementitious panel (SCP) panel  10  of the present invention employing strips  14  of reinforcing sheets attached to the SCP material  12  of the panel  10 . The strips  14  are implanted in cavities on the surface of the panel such that the upper surface of the strips  14  is flush with the uppermost surface of the SCP material  12 . The reinforcing strips  14  are typically metal, polymer or mesh having a thickness “A”. Typical metal reinforcing strips  14  have a thickness “A” of about 0.02 to about 0.07 inches (about 0.05 to about 0.2 cm) thick. The metal is typically steel or aluminum. For example, steel sheets about 25 to 14 gauge, e.g., 22 gauge. The metal can be replaced by one or more sheets of polymer, e.g., thermoplastic polymer or thermosetting polymer, or mesh, e.g. fiber glass mesh or carbon fiber mesh having a thickness “A” of about 1/32 to ¼ inch (about 0.08 to about 0.6 cm). 
       FIG. 2  is a cross-sectional view along view II-II of the panel  10  of  FIG. 1 . 
       FIG. 3  is a top view of a second embodiment of a metal reinforced SCP panel  11  of the present invention employing strips  15 ,  17  of reinforcing sheets embedded in the SCP material  13  of the panel  10 . The strips include strips  15  which wrap around opposed edges of the panel. In a second embodiment, the edges of the SCP panel are stiffened by placing metal along the SCP panel edges and bending the metal, e.g., ⅜ inch of metal edge, approximately 90 degrees to form a shallow tray to protect the edges of the SCP panel and add to the lateral fastener tear out along edges when the panel is loaded in shear. 
       FIG. 4  is a cross-sectional view along view IV-IV of the panel  11  of  FIG. 3 . 
       FIG. 5  is a top view of a third embodiment of a reinforced SCP panel  20  of the present invention having reinforcement strips  24  which protrude from a surface of the SCP material  22  of the panel  20 . 
       FIG. 6  is a cross-sectional view along view VI-VI of the panel  20  of  FIG. 5 . 
       FIG. 7  is a top view of a fourth embodiment of a reinforced SCP panel  30  of the present invention including reinforcing strips  34  which wrap around opposed sidewalls of the SCP material  32  of the panel  30 . Optionally, a reinforcing strip  36  is also attached to the SCP material  32 . 
       FIG. 8  is a cross-sectional view along view VIII-VIII of the panel  30  of  FIG. 7 . 
       FIG. 9  is a perspective view of a fifth embodiment of a reinforced SCP panel  40  of the present invention including reinforcing mesh  44  which wraps around opposed walls of the SCP material  46  of the panel  40 . 
       FIG. 10  is a top view of a sixth embodiment of a reinforced SCP panel  50  of the present invention including separate reinforcing corner pieces  54  and optional reinforcing strips  56  attached to the SCP material  52  of the panel  50 . 
       FIG. 11  is a cross-sectional view along view XI-XI of the panel  50  of  FIG. 10 . 
       FIG. 12  is a cross-sectional view along view XII-XII of the panel  50  of  FIG. 10 . 
       FIG. 13  is a top view of a seventh embodiment of a reinforced SCP panel  60  of the present invention including a central reinforcing strip  68  and separate reinforcing corner pieces  64 . Optionally, the panel  60  is further provided with two reinforcing strips  66  which contact the corner pieces  64 . 
       FIG. 14  is a cross-sectional view along view XIV-XIV of the panel  60  of  FIG. 13 . 
       FIG. 15  is a cross-sectional view along view XV-XV of the panel  60  of  FIG. 13 . 
       FIG. 16  is a top view of a eighth embodiment of a reinforced SCP panel  70  of the present invention employing an one piece reinforced border  74  placed into a notched area along the perimeter of one of the surfaces of the SCP material  72 . The outer perimeter of the border  74  overlaps the outer perimeter of the surface of the SCP material  72  to which the border  74  is attached. 
       FIG. 17  is a cross-sectional view along view XVII-XVII of the panel  70  of  FIG. 16 . 
       FIG. 18  is a top view of a ninth embodiment of a reinforced SCP panel  80  of the present invention which is the same as the embodiment of  FIG. 16 , but for employing a multi-piece reinforced border on one of the surfaces of the SCP material  82 . The border including corner pieces  84 , longitudinal side pieces  86  and transverse side pieces  88 . 
       FIG. 19  is a top view of a tenth embodiment of a reinforced SCP panel  90  of the present invention employing a panel  94 , having perforations  96 , attached to SCP material  92 . 
       FIG. 20  is a cross-sectional view along view XX-XX of the panel  90  of  FIG. 19 . 
       FIG. 21  is a perspective view of the panel  90  of  FIG. 19 .  FIG. 21  shows the panel  90  has a tongue  91  and a groove  93 . The other embodiments of the present invention also optionally have a tongue and groove on opposed sidewalls. 
       FIG. 22  is a perspective view of a portion of an eleventh embodiment of a reinforced SCP panel  95  of the present invention employing a panel  99 , with small perforations, attached to the SCP material  97 . Typical ranges for holes/perforations of  FIGS. 19 and 22  are as follows: 
     Range of hole size: 1/32″ diameter to 12″ diameter 
     Range of Hole density per square foot: 0.5 to 20,000 
     Surface area of reinforcement coverage range: 5% to 90% (this is different than the 10-80% reinforcement coverage range for the other reinforcement members). 
       FIG. 23  is a top view of a portion of a twelfth embodiment of a reinforced SCP panel  130  of the present invention employing a crossed pair of reinforcing members  134 ,  136 , attached to SCP material  132 . The crossed pair of reinforcing members  134 ,  136  overlap where they cross. 
       FIG. 24  is a cross-sectional view along view XXIV-XXIV of the reinforced SCP panel  130  of  FIG. 23 . 
       FIG. 25  is a top view of a portion of a thirteenth embodiment of a reinforced SCP panel  140  of the present invention employing three reinforcing members  144 ,  146 ,  148  attached to SCP material  142  to form a cross-shaped pattern. 
       FIG. 26  is a cross-sectional view along view XXVI-XXVI of the panel  140  of  FIG. 25 . 
       FIG. 27  is a top view of a portion of a fourteenth embodiment of a reinforced SCP panel of the present invention a crossed pair of reinforcing members  154 ,  155  attached to SCP material  152  to form a cross-shaped pattern and framed by a multi-piece reinforced border on one of the surfaces of the SCP material  152 . The border including corner pieces  153 , longitudinal side pieces  156  and transverse side pieces  151 . 
       FIG. 28  is a cross-sectional view along view XXVIII-XXVIII of the panel  150  of  FIG. 27 . 
       FIG. 29  is a side view of a multi-layer SCP panel  101  of the present invention having layers  102 ,  104 ,  106 ,  108 , with the reinforcement omitted for clarity. 
     Use of the Panels on Framing 
       FIG. 30  is a perspective view of a typical metal wall frame suitable for use with the reinforced SCP panels of the present invention. As shown in  FIG. 30 , a frame  110  for supporting the walls of the foundation  2  includes a lower track  112 , a plurality of metal studs  120 , and an optional spacer member  140 . SCP panels  101  ( FIG. 29 ) may be secured in any known manner to the outer side, and if desired the inner side, of the metal wall frame  110  to close the wall and form the exterior surface or surfaces of the wall. U.S. Pat. No. 6,694,695 to Collins et al., incorporated herein by reference, more fully describes the arrangement of this metal wall frame. 
     The studs  120  are generally C-shaped. More particularly, the studs  120  have a web  122  and a pair of L-shaped flanges  124  perpendicular to the web  122 . There are also one or more openings  126  in the web  122 . The openings  126  permit electrical conduit and plumbing to be run within the stud wall. The metal studs  120  are secured at one end  121  to lower track  112  by conventional fasteners  123  such as, for example, screws, rivets, etc. The lower track  112  is also C-shaped with a central web portion  114  and two legs  116  protruding from web  114 . In the present foundation system, the web  114  of the bottom track  112  is typically affixed to a floor (not shown) with conventional fasteners such as screws, bolts, rivets, etc. 
     An optional V-shaped stud spacer member  140  having a crease  149  is inserted through the aligned openings  126  provided through the webs  122  of the respective studs  120  such that notches  142  in the stud spacer member  140  engage the stud openings  126  of the web  122  of respective studs  120 . 
       FIG. 35  is a perspective view of a typical metal floor frame  460  suitable for use with the reinforced SCP panels of the present invention. The metal frame  460  has C-joist framing  450  supported on a header or longitudinal rim track  452 . In practice, the reinforced SCP panels may be mechanically or adhesively attached to the C-joists  450  or be not attached to the C-joists (i.e., be floating). 
     The joists were attached to the rim track  452  using screws into the side of the joist through a pre-bent tab and screws through the top of rim track into the joist  450 , at each end. Steel angles  451  were also fastened with screws to the respective joist  450  and to the rim track  452 . KATZ blocking  458  was fastened to the bottom of the joists  450  across the center line of the floor. The blocking  458  was attached using a screw through the end of each Katz blocking member  458 . In particular, the Katz blocking  458  is located between transverse joints  450  by being positioned staggered on either side of the midpoint and attached by screws. Additional horizontal blocking may be added to the rim track  452  on the load side to strengthen the rim track  452  for point loading purposes. Namely, blocking  457  for load support is provided along the longitudinal rim track between a number of transverse joists  450 . 20 inch long blocking  459  is fixed between each transverse end joist and the respective penultimate transverse end  452  joist generally along the longitudinal axis of the frame with screws. Typically a reinforced SCP panel could be attached to the frame by screws or adhesive. Afterwards, at the butt-joints and tongue and groove locations of the panels, an adhesive, for example ENERFOAM SF polyurethane foam adhesive manufactured by Flexible Products Company of Canada, Inc., could be applied in the joint. 
     U.S. Pat. No. 6,691,478 B2 to Daudet et al. discloses another example of a suitable metal flooring system. 
       FIG. 36  is a fragmentary schematic vertical section of a single-layer SCP panel  462  supported on metal frame  460  of  FIG. 35  in a system of the present invention. If desired a fastener (not shown) may attach the SCP panel to a C-joist of the metal frame  460 . In practice the floor may be mechanically or adhesively attached to the C-joist or be not attached to the C-joist (i.e., be floating). 
     The frames may be wood or any metal, e.g., steel or galvanized steel, framing systems suitable for supporting flooring. Typical metal frames include C-joists having openings therein for passing plumbing and electrical lines there through and headers for supporting the C-joists about the floor perimeter. Preferably the frames are metal to result in a non-combustible system. 
       FIG. 37  is a perspective view of SCP panels  416  of  FIG. 36  supported on a corrugated sheet  403  in the non-combustible flooring system of the present invention. 
     In  FIG. 38  the numeral  401  generally designates a composite flooring deck assembly comprising a corrugated sheet  403  supported from below by a joist (not shown, but which could for example be a C-joist or I-beam or any other suitable joist) and secured from above by mechanical fasteners  405  to a diaphragm  407  of SCP panels  416 . 
     Corrugated sheet  403  typically has flat portions  408  and  410  of substantially equal length joined by connector portions  412  providing straight, parallel, regular, and equally curved ridges and hollows. This configuration has a substantially equal distribution of surface area of the corrugated sheet above and below a neutral axis  414  (as seen in  FIG. 38 ). Optionally the panels  416  have a tongue  418  and groove  420  formed on opposite edges thereof to provide for continuous interlocking of flooring substrate panels  416  to minimize joint movement under moving and concentrated loads. 
     The embodiment of  FIG. 37  involves a design using a system of corrugated steel decking, designed using steel properties provided by the Steel Deck Institute (SDI) applied over steel joists and girders. A ceiling (not shown), such as gypsum drywall mounted on DIETRICH RC DELUXE channels may be attached to the bottoms of the joists or ceiling tiles and grid may be hung from the joists. An alternate is for the bottom surfaces of the steel to be covered with spray fiber or fireproofing materials. The steel joists which support the steel decking are any which can support the system. Typical steel joists may include those outlined by the SSMA (Steel Stud Manufacturer&#39;s Association) for use in corrugated steel deck systems, or proprietary systems, such as those sold by Dietrich as TRADE READY Brand joists. Joist spacing of 24 inches (61 cm) is common. However, spans between joists may be greater or less than this. C-joists and open web joists are typical. 
     In the particular embodiment of the invention illustrated in  FIG. 37 , SCP panels  416  have sufficient strength to create a structural bridge over the wide rib openings  422 .  FIG. 38  shows the SCP panels  416  attached to the corrugated sheet  403  by screws  405 . 
     As illustrated in  FIG. 39 , for a roof deck, spaced screws  405 , having screw heads  442  are oriented to form a series of generally triangular shaped horizontally disposed trusses (for example, truss T h  shown as the horizontal line between two of the screws  405 ) and a series of vertically disposed trusses T v  throughout the length and width of spans between spaced joists P (such as that shown in the embodiment of  FIG. 40 ) to increase the resistance to horizontal and vertical planar deflection of the roof deck. SCP panel  416  is described in more detail below. In the form of the invention illustrated in  FIG. 39  the diaphragm  407  comprises an SCP panel  416  positioned over a sheet of insulation material  430 . 
       FIG. 40  is a cross-sectional view of the SCP panel of  FIG. 36  supported on a corrugated sheet of a roofing system wherein the SCP panel  416  is secured over a sheet of insulation material  430  in the non-combustible building system of the present invention. In the form of the invention of  FIG. 40  the diaphragm  407  is secured to upper ridge portions  208  of the corrugated sheet  403  by threaded screws  405  having enlarged heads  442 . 
     The form of the system illustrated in  FIG. 40  is similar to that of  FIG. 39  except that a layer or sheet  430  of thermal insulation material is positioned over the SCP panels  416  to form the diaphragm  407 . Sheet  430  of insulation material typically comprises incombustible foamed polystyrene or other suitable insulation material. For example, other insulation material such as polyurethane, fiberglass, cork and the like may be employed in combination with or in lieu of the polystyrene. 
     Formulation of SCP Panels 
     The components used to make the shear resistant panels of the invention include hydraulic cement, calcium sulfate alpha hemihydrate, an active pozzolan such as silica fume, lime, ceramic microspheres, alkali-resistant glass fibers, superplasticizer (e.g., sodium salt of polynapthalene sulfonate), and water. Typically, both hydraulic cement and calcium sulfate alpha hemihydrate are present. Long term durability of the composite is compromised if calcium sulfate alpha hemihydrate is not present along with silica fume. Water/moisture durability is compromised when Portland cement is not present. Small amounts of accelerators and/or retarders may be added to the composition to control the setting characteristics of the green (i.e., uncured) material. Typical non-limiting additives include accelerators for hydraulic cement such as calcium chloride, accelerators for calcium sulfate alpha hemihydrate such as gypsum, retarders such as DTPA (diethylene triamine pentacetic acid), tartaric acid or an alkali salt of tartaric acid (e.g., potassium tartrate), shrinkage reducing agents such as glycols, and entrained air. 
     Panels of the invention will include a continuous phase in which alkali-resistant glass fibers and light weight filler, e.g., microspheres, are uniformly distributed. The continuous phase results from the curing of an aqueous mixture of the reactive powders, i.e., blend of hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), preferably including superplasticizer and/or other additives. 
     Typical weight proportions of embodiments of the reactive powders (inorganic binder), e.g., hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan and lime, in the invention, based on dry weight of the reactive powders, are shown in TABLE 1. TABLE 1A lists typical ranges of reactive powders, lightweight filler, and glass fibers in compositions of the present invention. 
     
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Weight Percent 
                 Typical Weight 
               
               
                 Reactive Powder 
                 (%) 
                 Percent (%) 
               
               
                   
               
             
             
               
                 Hydraulic Cement 
                 20-55 
                 25-40 
               
               
                 Calcium Sulfate Alpha Hemihydrate 
                 35-75 
                 45-65 
               
               
                 Pozzolan 
                  5-25 
                 10-15 
               
               
                 Lime 
                 up to 3.5 or 
                 0.75-1.25 
               
               
                   
                 from 0.2 to 3.5 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
             
           
               
                 TABLE 1A 
               
               
                   
               
               
                   
                   
                 Typical Weight 
               
               
                 SCP Composition (dry basis) 
                 Weight Percent (%) 
                 Percent (%) 
               
               
                   
               
             
             
               
                 Reactive Powder 
                 35-70 
                 35-68 
               
               
                 Lightweight Filler 
                 20-50 
                 23-49 
               
               
                 Glass Fibers 
                  5-20 
                  5-17 
               
               
                   
               
             
          
         
       
     
     Lime is not required in all formulations of the invention, but it has been found that adding lime provides superior panels and it usually will be added in amounts greater than about 0.2 wt. %. Thus, in most cases, the amount of lime in the reactive powders will be about 0.2 to 3.5 wt. %. 
     In the first embodiment of an SCP material for use in the invention, the dry ingredients of the composition will be the reactive powders (i.e., blend of hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), ceramic microspheres and alkali-resistant glass fibers, and the wet ingredients of the composition will be water and superplasticizer. The dry ingredients and the wet ingredients are combined to produce the panel of the invention. The ceramic microspheres are uniformly distributed in the matrix throughout the full thickness of the panel. Of the total weight of dry ingredients, the panel of the invention is formed from about 49 to 56 wt. % reactive powders, 35 to 42 wt. % ceramic microspheres and 7 to 12 wt. % alkali-resistant glass fibers. In a broad range, the panel of the invention is formed from 35 to 58 wt. % reactive powders, 34 to 49 wt. % lightweight filler, e.g., ceramic microspheres, and 6 to 17 wt. % alkali-resistant glass fibers of the total dry ingredients. The amounts of water and superplasticizer added to the dry ingredients will be sufficient to provide the desired slurry fluidity needed to satisfy processing considerations for any particular manufacturing process. The typical addition rates for water range between 35 to 60% of the weight of reactive powders and those for superplasticizer range between 1 to 8% of the weight of reactive powders. 
     The glass fibers are monofilaments having a diameter of about 5 to 25 microns (micrometers), preferably about 10 to 15 microns (micrometers). The monofilaments typically are combined in 100 filament strands, which may be bundled into rovings of about 50 strands. The length of the glass fibers will typically be about 0.25 to 1 or 2 inches (6.3 to 25 or 50 mm) or about 1 to 2 inches (25 to 50 mm) and broadly about 0.25 to 3 inches (6.3 to 76 mm). The fibers have random orientation, providing isotropic mechanical behavior in the plane of the panel. 
     A second embodiment of an SCP material suitable for use in the invention contains a blend of ceramic and glass microspheres uniformly distributed throughout the full thickness of the panel. Accordingly, the dry ingredients of the composition will be the reactive powders (hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), ceramic microspheres, glass microspheres, and alkali-resistant glass fibers, and the wet ingredients of the composition will be water and superplasticizer. The dry ingredients and the wet ingredients will be combined to produce the panel of the invention. The volume fraction of the glass microspheres in the panel will typically be in the range of 7 to 15% of the total volume of dry ingredients. Of the total weight of dry ingredients, the panel of the invention is formed from about 54 to 65 wt. % reactive powders, 25 to 35 wt. % ceramic microspheres, 0.5 to 0.8 wt. % glass microspheres, and 6 to 10 wt. % alkali-resistant glass fibers. In the broad range, the panel of the invention is formed from 42 to 68 wt. % reactive powders, 23 to 43 wt. % lightweight fillers, e.g., ceramic microspheres, 0.2 to 1.0 wt. % glass microspheres, and 5 to 15 wt. % alkali-resistant glass fibers, based on the total dry ingredients. The amounts of water and superplasticizer added to the dry ingredients will be adjusted to provide the desired slurry fluidity needed to satisfy the processing considerations for any particular manufacturing process. The typical addition rates for water range between 35 to 70% of the weight of reactive powders, but could be greater than 60% up to 70% (weight ratio of water to reactive powder of 0.6/1 to 0.7/1), preferably 65% to 75%, when it is desired to use the ratio of water-to-reactive powder to reduce panel density and improve cutability. The amount of superplasticizer will range between 1 to 8% of the weight of reactive powders. The glass fibers are monofilaments having a diameter of about 5 to 25 microns (micrometers), preferably about 10 to 15 microns (micrometers). They typically are bundled into strands and rovings as discussed above. The length of the glass fibers typically is about 1 to 2 inches (25 to 50 mm) and broadly about 0.25 to 3 inches (6.3 to 76 mm). The fibers will have random orientation providing isotropic mechanical behavior in the plane of the panel. 
     A third embodiment of SCP material suitable for use in the invention, contains a multi-layer structure in the panel created where the outer layer(s) have improved nailability (fastening ability)/cutability. This is achieved by increasing the water-to-cement ratio in the outer layer(s), and/or changing the amount of filler, and/or adding an amount of polymer microspheres sufficiently small such that the panel remains noncombustible. The core of the panel will typically contain ceramic microspheres uniformly distributed throughout the layer thickness or alternatively, a blend of one or more of ceramic microspheres, glass microspheres and fly ash cenospheres. 
     The dry ingredients of the core layer of this third embodiment are the reactive powders (typically hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), lightweight filler particles (typically microspheres such as ceramic microspheres alone or one or more of ceramic microspheres, glass microspheres and fly ash cenospheres), and alkali-resistant glass fibers, and the wet ingredients of the core layer are water and superplasticizer. The dry ingredients and the wet ingredients will be combined to produce the core layer of the panel of the invention. Of the total weight of dry ingredients, the core of the panel of the invention preferably is formed from about 49 to 56 wt. % reactive powders, 35 to 42 wt. % hollow ceramic microspheres and 7 to 12 wt. % alkali-resistant glass fibers, or alternatively, about 54 to 65 wt. % reactive powders, 25 to 35 wt. % ceramic microspheres, 0.5 to 0.8 wt. % glass microspheres or fly ash cenospheres, and 6 to 10 wt. % alkali-resistant glass fibers. In the broad range, the core layer of the panel of this embodiment of the present invention is typically formed by about 35 to 58 wt. % reactive powders, 34 to 49 wt. % lightweight fillers, e.g., ceramic microspheres, and 6 to 17 wt. % alkali-resistant glass fibers, based on the total dry ingredients, or alternatively, about 42 to 68 wt. % of reactive powders, 23 to 43 wt. % ceramic microspheres, up to 1.0 wt. %, preferably 0.2 to 1.0 wt. %, other lightweight filler, e.g., glass microspheres or fly ash cenospheres, and 5 to 15 wt. % alkali-resistant glass fibers. The amounts of water and superplasticizer added to the dry ingredients will be adjusted to provide the desired slurry fluidity needed to satisfy the processing considerations for any particular manufacturing process. The typical addition rates for water will range between 35 to 70% of the weight of reactive powders but will be greater than 60% up to 70% when it is desired to use the ratio of water-to-reactive powders to reduce panel density and improve nailability and those for superplasticizer will range between 1 to 8% of the weight of reactive powders. When the ratio of water-to-reactive powder is adjusted, the slurry composition will be adjusted to provide the panel of the invention with the desired properties. 
     There is generally an absence of polymer microspheres and an absence of polymer fibers that would cause the SCP panel to become combustible. 
     The dry ingredients of the outer layer(s) of this third embodiment will be the reactive powders (typically hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), lightweight filler particles (typically microspheres such as ceramic microspheres alone or one or more of ceramic microspheres, glass microspheres and fly ash cenospheres), and alkali-resistant glass fibers, and the wet ingredients of the outer layer(s) will be water and superplasticizer. The dry ingredients and the wet ingredients are combined to produce the outer layers of the panel of the invention. In the outer layer(s) of the panel of this embodiment of the present invention, the amount of water is selected to furnish good fastening and cutting ability to the panel. Of the total weight of dry ingredients, the outer layer(s) of the panel of the invention preferably are formed from about 54 to 65 wt. % reactive powders, 25 to 35 wt. % ceramic microspheres, 0 to 0.8 wt. % glass microspheres, and 6 to 10 wt. % alkali-resistant glass fibers. In the broad range, the outer layers of the panel of the invention are formed from about 42 to 68 wt. % reactive powders, 23 to 43 wt. % ceramic microspheres, up to 1.0 wt. % glass microspheres (and/or fly ash cenospheres), and 5 to 15 wt. % alkali-resistant glass fibers, based on the total dry ingredients. The amounts of water and superplasticizer added to the dry ingredients are adjusted to provide the desired slurry fluidity needed to satisfy the processing considerations for any particular manufacturing process. The typical addition rates for water range between 35 to 70% of the weight of reactive powders and particularly greater than 60% up to 70% when the ratio of water-to-reactive powders is adjusted to reduce panel density and improve nailability, and typical addition rates for superplasticizer will range between 1 to 8% of the weight of reactive powders. The preferable thickness of the outer layer(s) ranges between 1/32 to 4/32 inches (0.8 to 3.2 mm) and the thickness of the outer layer when only one is used will be less than ⅜ of the total thickness of the panel. 
     In both the core and outer layer(s) of this embodiment of the present invention, the glass fibers are monofilaments having a diameter of about 5 to 25 microns (micrometers), preferably 10 to 15 microns (micrometers). The monofilaments typically are bundled into strands and rovings as discussed above. The length typically is about 1 to 2 inches (25 to 50 mm) and broadly about 0.25 to 3 inches (6.3 to 76 mm). The fiber orientation will be random, providing isotropic mechanical behavior in the plane of the panel. 
     A fourth embodiment of SCP material for use in the present invention provides a multi-layer panel having a density of 65 to 90 pounds per cubic foot and capable of resisting shear loads when fastened to framing and comprising a core layer of a continuous phase resulting from the curing of an aqueous mixture, a continuous phase resulting from the curing of an aqueous mixture comprising, on a dry basis, 35 to 70 weight % reactive powder, 20 to 50 weight percent lightweight filler, and 5 to 20 weight % glass fibers, the continuous phase being reinforced with glass fibers and containing the lightweight filler particles, the lightweight filler particles having a particle specific gravity of from 0.02 to 1.00 and an average particle size of about 10 to 500 microns (micrometers); and at least one outer layer of respectively another continuous phase resulting from the curing of an aqueous mixture comprising, on a dry basis, 35 to 70 weight % reactive powder, 20 to 50 weight percent lightweight filler, and 5 to 20 weight % glass fibers, the continuous phase being reinforced with glass fibers and containing the lightweight filler particles, the lightweight filler particles having a particle specific gravity of from 0.02 to 1.00 and an average particle size of about 10 to 500 microns (micrometers) on each opposed side of the inner layer, wherein the at least one outer layer has a higher percentage of glass fibers than the inner layer. 
     Making a Panel of the Invention 
     The reactive powders, e.g., blend of hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), and lightweight filler, e.g., microspheres, are blended in the dry state in a suitable mixer. 
     Then, water, a superplasticizer (e.g., the sodium salt of polynapthalene sulfonate), and the pozzolan (e.g., silica fume or metakaolin) are mixed in another mixer for 1 to 5 minutes. If desired, a retarder (e.g., potassium tartrate) is added at this stage to control the setting characteristics of the slurry. The dry ingredients are added to the mixer containing the wet ingredients and mixed for 2 to 10 minutes to form smooth homogeneous slurry. 
     The slurry is then combined with glass fibers, in any of several ways, with the objective of obtaining a uniform slurry mixture. The cementitious panels are then formed by pouring the slurry containing fibers into an appropriate mold of desired shape and size. If necessary, vibration is provided to the mold to obtain good compaction of material in the mold. The panel is given required surface finishing characteristics using an appropriate screed bar or trowel. The panel may then be embossed to provide indentations and the reinforcement members are inserted into the indentations and attached to the panel. If desired, rather than placing the reinforcement members into indentations, they may be placed on the non-indented surface to protrude from the panel. 
     One of a number of methods to make multi-layer SCP panels is as follows. The reactive powders, e.g., blend of hydraulic cement, calcium sulfate alpha hemihydrate, pozzolan, and lime), and lightweight filler, e.g., microspheres, are blended in the dry state in a suitable mixer. Then, water, a superplasticizer (e.g., the sodium salt of polynapthalene sulfonate), and the pozzolan (e.g., silica fume or metakaolin) are mixed in another mixer for 1 to 5 minutes. If desired, a retarder (e.g., potassium tartrate) is added at this stage to control the setting characteristics of the slurry. The dry ingredients are added to the mixer containing the wet ingredients and mixed for 2 to 10 minutes to form a smooth homogeneous slurry. 
     The slurry may be combined with the glass fibers in several ways, with the objective of obtaining a uniform mixture. The glass fibers typically will be in the form of rovings that are chopped into short lengths. In a preferred embodiment, the slurry and the chopped glass fibers are concurrently sprayed into a panel mold. Preferably, spraying is done in a number of passes to produce thin layers, preferably up to about 0.25 inches (6.3 mm) thick, which are built up into a uniform panel having no particular pattern and with a thickness of ¼ to 1 inch (6.3 to 25.4 mm). For example, in one application, a 3×5 ft (0.91×1.52 m) panel was made with six passes of the spray in the length and width directions. As each layer is deposited, a roller may be used to assure that the slurry and the glass fibers achieve intimate contact. The layers may be leveled with a screed bar or other suitable means after the rolling step. Typically, compressed air will be used to atomize the slurry. As it emerges from the spray nozzle, the slurry mixes with glass fibers that have been cut from a roving by a chopper mechanism mounted on the spray gun. The uniform mixture of slurry and glass fibers is deposited in the panel mold as described above. 
     If desired the outer surface layers of the panel may contain polymer spheres, or be otherwise constituted, in order that the fasteners used to attach the panel to framing can be driven easily. The preferable thickness of such layers will be about 1/32 inches to 4/32 inches (0.8 to 3.2 mm). The same procedure described above by which the core of the panel is made may be used to apply the outer layers of the panel. 
     Other methods of depositing a mixture of the slurry and glass fibers will occur to those familiar with the panel-making art. For example, rather than using a batch process to make each panel, a continuous sheet may be prepared in a similar manner, which after the material has sufficiently set, can be cut into panels of the desired size. The percentage of fibers relative to the volume of slurry typically constitutes approximately in the range of 0.5% to 3%, for example 1.5%. Typical panels have a thickness of about ¼ to 1½ inches (6.3 to 38.1 mm). 
     The SCP panels are typically embossed with a pattern sufficiently deep such that the reinforcement when inserted into the pattern has an outer surface flush with the outer surface of the panel. Although, if desired, the embossing may be omitted such that the reinforcement upper surface will protrude from the surface of the SCP panel. 
     The reinforcement members are preferably at least temporarily affixed to the SCP panel by an adhesive applied to one of the mating major surfaces. Other attachment means of affixing reinforcement members to SCP panel, such as double sided tape, may be employed also. The adhesive may be epoxy or glue, and may be applied by various means such as brushing or spraying, for example. Further, the adhesive may be applied to a portion or portions of one or both of the major surfaces. However, adhesive is preferably spread over the extent of one of the major surfaces of one of either wallboard panel or reinforcement piece and is a water soluble latex based glue. The amount of adhesive applied to adhere the SCP panel and reinforcement piece together is an amount at least sufficient to hold these two members together such that the composite wallboard structure can be handled and constructed into a building wall structure. Thus, the adhesive applied between the SCP panel and reinforcement piece is of sufficient quantity to hold these two members together while the composite structure is being handled, shipped and attached to building wall framing studs or floor framing joists, in typical building construction processes. 
     The reinforced SCP panel could be made by automated processes. For example, an SCP panel could be manufactured and provided by automated machinery well known in the industry. The SCP panel could continue its processing by spraying one of its surfaces with an adhesive utilizing a spraying device stationed over SCP panel. A reinforcement piece such as a metal strip can thereafter be laid on the adhesive by a robotics mechanism. 
     Another method of making panels of the present invention is by using the process steps disclosed in U.S. patent application Ser. No. 10/666,294 incorporated herein by reference. U.S. patent application Ser. No. 10/666,294, incorporated herein by reference, discloses after one of an initial deposition of loosely distributed, chopped fibers or a layer of slurry upon a moving web, fibers are deposited upon the slurry layer. An embedment device compacts the recently deposited fibers into the slurry, after which additional layers of slurry, then chopped fibers are added, followed by more embedment. The process is repeated for each layer of the board, as desired. Then the board is typically embossed to have a pattern of indentations and the reinforcement members are inserted into the indentations and attached to the board. 
     More specifically, U.S. patent application Ser. No. 10/666,294 discloses a multi-layer process for producing structural cementitious panels, including: (a.) providing a moving web; (b.) one of depositing a first layer of loose fibers and (c.) depositing a layer of settable slurry upon the web; (d.) depositing a second layer of loose fibers upon the slurry; (e.) embedding the second layer of fibers into the slurry; and (f.) repeating the slurry deposition of step (c.) through step (d.) until the desired number of layers of settable fiber-enhanced slurry in the panel is obtained. 
       FIG. 31  is a diagrammatic elevational view of an apparatus which is suitable for performing the process of U.S. patent application Ser. No. 10/666,294, but for adding embossing capability to the forming device  394  and adding a reinforcement member attaching station  400 . 
     Referring now to  FIG. 31 , a structural panel production line is diagrammatically shown and is generally designated  310 . The production line  310  includes a support frame or forming table  312  having a plurality of legs  313  or other supports. Included on the support frame  312  is a moving carrier  314 , such as an endless rubber-like conveyor belt with a smooth, water-impervious surface, however porous surfaces are contemplated. As is well known in the art, the support frame  312  may be made of at least one table-like segment, which may include designated legs  313 . The support frame  312  also includes a main drive roll  316  at a distal end  318  of the frame, and an idler roll  320  at a proximal end  322  of the frame. Also, at least one belt tracking and/or tensioning device  324  is preferably provided for maintaining a desired tension and positioning of the carrier  314  upon the rolls  316 ,  320 . 
     Also, in the preferred embodiment, a web  326  of Kraft paper, release paper, and/or other webs of support material designed for supporting slurry prior to setting, as is well known in the art, may be provided and laid upon the carrier  314  to protect it and/or keep it clean. However, it is also contemplated that the panels produced by the present line  310  are formed directly upon the carrier  314 . In the latter situation, at least one belt washing unit  328  is provided. The carrier  314  is moved along the support frame  312  by a combination of motors, pulleys, belts or chains which drive the main drive roll  316  as is known in the art. It is contemplated that the speed of the carrier  314  may vary to suit the application. 
     In the apparatus of  FIG. 31 , structural cementitious panel production is initiated by one of depositing a layer of loose, chopped fibers  330  or a layer of slurry upon the web  326 . An advantage of depositing the fibers  330  before the first deposition of slurry is that fibers will be embedded near the outer surface of the resulting panel. A variety of fiber depositing and chopping devices are contemplated by the present line  310 , however the preferred system employs at least one rack  331  holding several spools  332  of fiberglass cord, from each of which a cord  334  of fiber is fed to a chopping station or apparatus, also referred to as a chopper  336 . 
     The chopper  336  includes a rotating bladed roll  338  from which project radially extending blades  340  extending transversely across the width of the carrier  314 , and which is disposed in close, contacting, rotating relationship with an anvil roll  342 . In the preferred embodiment, the bladed roll  338  and the anvil roll  342  are disposed in relatively close relationship such that the rotation of the bladed roll  338  also rotates the anvil roll  342 , however the reverse is also contemplated. Also, the anvil roll  342  is preferably covered with a resilient support material against which the blades  340  chop the cords  334  into segments. The spacing of the blades  340  on the roll  338  determines the length of the chopped fibers. As is seen in  FIG. 31 , the chopper  336  is disposed above the carrier  314  near the proximal end  322  to maximize the productive use of the length of the production line  310 . As the fiber cords  334  are chopped, the fibers  330  fall loosely upon the carrier web  326 . 
     Next, a slurry feed station, or a slurry feeder  344  receives a supply of slurry  346  from a remote mixing location  347  such as a hopper, bin or the like. It is also contemplated that the process may begin with the initial deposition of slurry upon the carrier  314 . The slurry is preferably comprised of varying amounts of Portland cement, gypsum, aggregate, water, accelerators, plasticizers, foaming agents, fillers and/or other ingredients, and described above and in the patents listed above which have been incorporated by reference for producing SCP panels. The relative amounts of these ingredients, including the elimination of some of the above or the addition of others, may vary to suit the use. 
     While various configurations of slurry feeders  344  are contemplated which evenly deposit a thin layer of slurry  346  upon the moving carrier  314 , the preferred slurry feeder  344  includes a main metering roll  348  disposed transversely to the direction of travel of the carrier  314 . A companion or back up roll  350  is disposed in close parallel, rotational relationship to the metering roll  348  to form a nip  352  there between. A pair of sidewalls  354 , preferably of non-stick material such as Teflon® brand material or the like, prevents slurry  346  poured into the nip  352  from escaping out the sides of the feeder  344 . 
     The feeder  344  deposits an even, relatively thin layer of the slurry  346  upon the moving carrier  314  or the carrier web  326 . Suitable layer thicknesses range from about 0.05 inch to 0.20 inch. However, with four layers preferred in the preferred structural panel produced by the present process, and a suitable building panel being approximately 0.5 inch, an especially preferred slurry layer thickness is approximately 0.125 inch. 
     Referring now to  FIGS. 31 and 32 , to achieve a slurry layer thickness as described above, several features are provided to the slurry feeder  344 . First, to ensure a uniform disposition of the slurry  346  across the entire web  326 , the slurry is delivered to the feeder  344  through a hose  356  located in a laterally reciprocating, cable driven, fluid powered dispenser  358  of the type well known in the art. Slurry flowing from the hose  356  is thus poured into the feeder  344  in a laterally reciprocating motion to fill a reservoir  359  defined by the rolls  348 ,  350  and the sidewalls  354 . Rotation of the metering roll  348  thus draws a layer of the slurry  346  from the reservoir. 
     Next, a thickness monitoring or thickness control roll  360  is disposed slightly above and/or slightly downstream of a vertical centerline of the main metering roll  348  to regulate the thickness of the slurry  346  drawn from the feeder reservoir  357  upon an outer surface  362  of the main metering roll  348 . Also, the thickness control roll  360  allows handling of slurries with different and constantly changing viscosities. The main metering roll  348  is driven in the same direction of travel “T” as the direction of movement of the carrier  314  and the carrier web  326 , and the main metering roll  348 , the backup roll  350  and the thickness monitoring roll  360  are all rotatably driven in the same direction, which minimizes the opportunities for premature setting of slurry on the respective moving outer surfaces. As the slurry  346  on the outer surface  362  moves toward the carrier web  326 , a transverse stripping wire  364  located between the main metering roll  348  and the carrier web  326  ensures that the slurry  346  is completely deposited upon the carrier web and does not proceed back up toward the nip  352  and the feeder reservoir  359 . The stripping wire  364  also helps keep the main metering roll  348  free of prematurely setting slurry and maintains a relatively uniform curtain of slurry. 
     A second chopper station or apparatus  366 , preferably identical to the chopper  336 , is disposed downstream of the feeder  344  to deposit a second layer of fibers  368  upon the slurry  346 . In the preferred embodiment, the chopper apparatus  366  is fed cords  334  from the same rack  331  that feeds the chopper  336 . However, it is contemplated that separate racks  331  could be supplied to each individual chopper, depending on the application. 
     Referring now to  FIGS. 31 and 33 , next, an embedment device, generally designated  370  is disposed in operational relationship to the slurry  346  and the moving carrier  314  of the production line  310  to embed the fibers  368  into the slurry  346 . While a variety of embedment devices are contemplated, including, but not limited to vibrators, sheep&#39;s foot rollers and the like, in the preferred embodiment, the embedment device  370  includes at least a pair of generally parallel shafts  372  mounted transversely to the direction of travel “T” of the carrier web  326  on the frame  312 . Each shaft  372  is provided with a plurality of relatively large diameter disks  374  which are axially separated from each other on the shaft by small diameter disks  376 . 
     During SCP panel production, the shafts  372  and the disks  374 ,  376  rotate together about the longitudinal axis of the shaft. As is well known in the art, either one or both of the shafts  372  may be powered, and if only one is powered, the other may be driven by belts, chains, gear drives or other known power transmission technologies to maintain a corresponding direction and speed to the driving roll. The respective disks  374 ,  376  of the adjacent, preferably parallel shafts  372  are intermeshed with each other for creating a “kneading” or “massaging” action in the slurry, which embeds the fibers  368  previously deposited thereon. In addition, the close, intermeshed and rotating relationship of the disks  372 ,  374  prevents the buildup of slurry  346  on the disks, and in effect creates a “self-cleaning” action which significantly reduces production line downtime due to premature setting of clumps of slurry. 
     The intermeshed relationship of the disks  374 ,  376  on the shafts  372  includes a closely adjacent disposition of opposing peripheries of the small diameter spacer disks  376  and the relatively large diameter main disks  374 , which also facilitates the self-cleaning action. As the disks  374 ,  376  rotate relative to each other in close proximity (but preferably in the same direction), it is difficult for particles of slurry to become caught in the apparatus and prematurely set. By providing two sets of disks  374  which are laterally offset relative to each other, the slurry  346  is subjected to multiple acts of disruption, creating a “kneading” action which further embeds the fibers  368  in the slurry  346 . 
     Once the fibers  368  have been embedded, or in other words, as the moving carrier web  326  passes the embedment device  370 , a first layer  377  of the SCP panel is complete. In the preferred embodiment, the height or thickness of the first layer  377  is in the approximate range of 0.05-0.20 inches. This range has been found to provide the desired strength and rigidity when combined with like layers in a SCP panel. However, other thicknesses are contemplated depending on the application. 
     To build a structural cementitious panel of desired thickness, additional layers are needed. To that end, a second slurry feeder  378 , which is substantially identical to the feeder  344 , is provided in operational relationship to the moving carrier  314 , and is disposed for deposition of an additional layer  380  of the slurry  346  upon the existing layer  377 . 
     Next, an additional chopper  382 , substantially identical to the choppers  336  and  366 , is provided in operational relationship to the frame  312  to deposit a third layer of fibers  384  provided from a rack (not shown) constructed and disposed relative to the frame  312  in similar fashion to the rack  331 . The fibers  384  are deposited upon the slurry layer  380  and are embedded using a second embedment device  386 . Similar in construction and arrangement to the embedment device  370 , the second embedment device  386  is mounted slightly higher relative to the moving carrier web  314  so that the first layer  377  is not disturbed. In this manner, the second layer  380  of slurry and embedded fibers is created. 
     Referring now to  FIG. 31 , with each successive layer of settable slurry and fibers, an additional slurry feeder station  344 ,  378 ,  402  followed by a fiber chopper  336 ,  366 ,  382 ,  404  and an embedment device  370 ,  386 ,  406  is provided on the production line  310 . In the preferred embodiment, four total layers (see for example, the panel  101  of  FIG. 29 ) are provided to form the SCP panel. Upon the disposition of the four layers of fiber-embedded settable slurry as described above, a forming device  394  is preferably provided to the frame  312  to shape an upper surface  396  of the panel. Such forming devices  394  are known in the settable slurry/board production art, and typically are spring-loaded or vibrating plates which conform the height and shape of the multi-layered panel to suit the desired dimensional characteristics. 
     The panel which is made has multiple layers (see for example layers  22 ,  24 ,  26 ,  28  of panel  101  of  FIG. 29 ) which upon setting form an integral, fiber-reinforced mass. Provided that the presence and placement of fibers in each layer are controlled by and maintained within certain desired parameters as is disclosed and described below, it will be virtually impossible to delaminate the panel. 
     At this point, the layers of slurry have begun to set, and the respective panels are separated from each other by a cutting device  398 , which in the preferred embodiment is a water jet cutter. Other cutting devices, including moving blades, are considered suitable for this operation, provided that they can create suitably sharp edges in the present panel composition. The cutting device  398  is disposed relative to the line  310  and the frame  312  so that panels are produced having a desired length, which may be different from the representation shown in  FIG. 31 . Since the speed of the carrier web  314  is relatively slow, the cutting device  398  may be mounted to cut perpendicularly to the direction of travel of the web  314 . With faster production speeds, such cutting devices are known to be mounted to the production line  310  on an angle to the direction of web travel. Upon cutting, the separated panels  321  are stacked for further handling, packaging, storage and/or shipment as is well known in the art. 
     Then the reinforcement members are inserted into the pattern downstream of the forming device  394  and adhered with glue or other means to the SCP panel in an insertion and attaching station  400 . If desired, the forming device  394  embosses the SCP panel to make indentations in the SCP panels and the reinforcement members are placed into the indentations in the insertion and attaching station  400 . 
     In quantitative terms, the influence of the number of fiber and slurry layers, the volume fraction of fibers in the panel, and the thickness of each slurry layer, and fiber strand diameter on fiber embedment efficiency has been investigated. In the analysis, the following parameters were identified: 
     v T =Total composite volume 
     v s =Total panel slurry volume 
     v f =Total panel fiber volume 
     v f,l =Total fiber volume/layer 
     v T,l =Total composite volume/layer 
     v s,l =Total slurry volume/layer 
     N l =Total number of slurry layers; Total number of fiber layers 
     V f =Total panel fiber volume fraction 
     d f =Equivalent diameter of individual fiber strand 
     l f =Length of individual fiber strand 
     t=Panel thickness 
     t l =Total thickness of individual layer including slurry and fibers 
     t s,l =Thickness of individual slurry layer 
     n f,l , n f1,l , n f2,l =Total number of fibers in a fiber layer 
     s f,l   P , s f,l   P , s f2,l   P =Total projected surface area of fibers contained in a fiber layer 
     S f,l   P , S f1,l   P , S f2,l   P =Projected fiber surface area fraction for a fiber layer. 
     Projected Fiber Surface Area Fraction, S f,l   P    
     Assume a panel composed of equal number of slurry and fiber layers. Let the number of these layers be equal to N l , and the fiber volume fraction in the panel be equal to V f . 
     In summary, the projected fiber surface area fraction, S f,l   P  of a layer of fiber network being deposited over a distinct slurry layer is given by the following mathematical relationship: 
     
       
         
           
             
               S 
               
                 f 
                 , 
                 l 
               
               P 
             
             = 
             
               
                 
                   4 
                   ⁢ 
                   
                     V 
                     f 
                   
                   ⁢ 
                   t 
                 
                 
                   π 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     N 
                     l 
                   
                   ⁢ 
                   
                     d 
                     f 
                   
                 
               
               = 
               
                 
                   4 
                   ⁢ 
                   
                     V 
                     f 
                   
                   * 
                   
                     t 
                     
                       s 
                       , 
                       l 
                     
                   
                 
                 
                   π 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     
                       d 
                       f 
                     
                     ⁡ 
                     
                       ( 
                       
                         1 
                         - 
                         
                           V 
                           f 
                         
                       
                       ) 
                     
                   
                 
               
             
           
         
       
     
     where, V f  is the total panel fiber volume fraction, t is the total panel thickness, d f  is the diameter of the fiber strand, N l  is the total number of fiber layers and t s,l  is the thickness of the distinct slurry layer being used. 
     Accordingly, to achieve good fiber embedment efficiency, the objective function becomes keeping the fiber surface area fraction below a certain critical value. It is noteworthy that by varying one or more variables appearing in the Equations 8 and 10, the projected fiber surface area fraction can be tailored to achieve good fiber embedment efficiency. 
     Different variables that affect the magnitude of projected fiber surface area fraction are identified and approaches have been suggested to tailor the magnitude of “projected fiber surface area fraction” to achieve good fiber embedment efficiency. These approaches involve varying one or more of the following variables to keep projected fiber surface area fraction below a critical threshold value: number of distinct fiber and slurry layers, thickness of distinct slurry layers and diameter of fiber strand. 
     Based on this fundamental work, the typical magnitudes of the projected fiber surface area fraction, S f,l   P  have been discovered to be as follows: 
     Typical projected fiber surface area fraction, S f,l   P &lt;0.65 
     Another range of typical projected fiber surface area fraction, S f,l   P &lt;0.45 
     For a design panel fiber volume fraction, V f , achievement of the aforementioned preferred magnitudes of projected fiber surface area fraction can be made possible by tailoring one or more of the following variables—total number of distinct fiber layers, thickness of distinct slurry layers and fiber strand diameter. In particular, the desirable ranges for these variables that lead to the typical magnitudes of projected fiber surface area fraction are as follows: 
     Thickness of Distinct Slurry Layers in Multiple Layer SCP panels, t s,l    
     Preferred thickness of distinct slurry layers, t s,l ≦0.20 inches 
     More Preferred thickness of distinct slurry layers, t s,l ≦0.12 inches 
     Most preferred thickness of distinct slurry layers, t s,l ≦0.08 inches 
     Number of Distinct Fiber Layers in Multiple Layer SCP panels, N 1   
     
       
         
               
               
               
             
           
               
                   
               
             
             
               
                   
                 Preferred number of distinct fiber layers, N l   
                 ≧4 
               
               
                   
                 Most preferred number of distinct fiber layers, N l   
                 ≧6 
               
               
                   
               
             
          
         
       
     
     Fiber Strand Diameter, d f   
     
       
         
               
               
               
             
           
               
                   
               
             
             
               
                   
                 Preferred fiber strand diameter, d f   
                 ≧30 tex 
               
               
                   
                 Most preferred fiber strand diameter, d f   
                 ≧70 tex 
               
               
                   
               
             
          
         
       
     
     In using the panels as structural subflooring or flooring underlayment, they preferably will be made with a tongue and groove construction, which may be made by shaping the edges of the panel during casting or before use by cutting the tongue and groove with a router. Preferably, the tongue and groove will be tapered, as shown in FIGS.  3  and  4 A-C, the taper providing easy installation of the panels of the invention. 
     Additional details of variations on the process and the amounts of fibers embedded in typical SCP panels for use in the present invention are provided by the following patents and patent applications: 
     U.S. Pat. No. 6,986,812, to Dubey et al. entitled SLURRY FEED APPARATUS FOR FIBER-REINFORCED STRUCTURAL CEMENTITIOUS PANEL PRODUCTION, herein incorporated by reference in its entirety; and 
     the following co-pending, commonly assigned, United States patent applications, all herein incorporated by reference in their entirety: 
     United States Patent Application Publication No. 2005/0064164 A1 to Dubey et al., application Ser. No. 10/666,294, entitled, MULTI-LAYER PROCESS AND APPARATUS FOR PRODUCING HIGH STRENGTH FIBER-REINFORCED STRUCTURAL CEMENTITIOUS PANELS; 
     United States Patent Application Publication No. 2005/0064055 A1 to Porter, application Ser. No. 10/665,541, entitled EMBEDMENT DEVICE FOR FIBER-ENHANCED SLURRY; 
     U.S. patent application Ser. No. 11/555,647, entitled PROCESS AND APPARATUS FOR FEEDING CEMENTITIOUS SLURRY FOR FIBER-REINFORCED STRUCTURAL CEMENT PANELS, filed Nov. 1, 2006; 
     U.S. patent application Ser. No. 11/555,655, entitled METHOD FOR WET MIXING CEMENTITIOUS SLURRY FOR FIBER-REINFORCED STRUCTURAL CEMENT PANELS, filed Nov. 1, 2006; 
     U.S. patent application Ser. No. 11/555,658, entitled APPARATUS AND METHOD FOR WET MIXING CEMENTITIOUS SLURRY FOR FIBER-REINFORCED STRUCTURAL CEMENT PANELS, filed Nov. 1, 2006; 
     U.S. patent application Ser. No. 11/555,661, entitled PANEL SMOOTHING PROCESS AND APPARATUS FOR FORMING A SMOOTH CONTINUOUS SURFACE ON FIBER-REINFORCED STRUCTURAL CEMENT PANELS, filed Nov. 1, 2006; 
     U.S. patent application Ser. No. 11/555,665, entitled WET SLURRY THICKNESS GAUGE AND METHOD FOR USE OF SAME, filed Nov. 1, 2006; 
     U.S. patent application Ser. No. 11/591,793, entitled MULTI-LAYER PROCESS AND APPARATUS FOR PRODUCING HIGH STRENGTH FIBER-REINFORCED STRUCTURAL CEMENTITIOUS PANELS WITH ENHANCED FIBER CONTENT, filed Nov. 1, 2006; 
     U.S. patent application Ser. No. 11/591,957, entitled EMBEDMENT ROLL DEVICE, filed Nov. 1, 2006. 
     Properties 
     The SCP panel and frame systems employing such SCP panels (prior to including reinforcement) preferably have one or more of the properties listed in TABLES 2A-2D. A number of these properties will be improved by reinforcement while others, for example, mold and bacterial resistance are expected to remain substantially the same. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2A 
               
               
                   
               
               
                   
                   
                   
                 Preferred 
                   
                   
               
               
                 Physical 
                 ASTM Test 
                   
                 Target 
                   
                   
               
               
                 Characteristics 
                 Method 
                 Unit 
                 Value 
                 Typical Range 
                 Notes 
               
               
                   
               
             
             
               
                 Non- 
                 E-136 
                 Weight 
                 ≦50% 
                 ≦50% 
                 From Sec. 8, E- 
               
               
                 Combustibility 
                   
                 Loss 
                   
                   
                 136 
               
               
                   
                   
                 Temp 
                 ≦54° F. 
                 ≦54° 
                 From Sec. 8, E- 
               
               
                   
                   
                 Rise 
                   
                   
                 136 
               
               
                   
                   
                 30 
                 No 
                 No 
                 From Sec. 8, E- 
               
               
                   
                   
                 seconds 
                 flaming 
                 flaming 
                 136 
               
               
                 Water 
                   
                   
                   
                   
                   
               
               
                 Durability 
                   
                   
                   
                   
                   
               
               
                 Flex. Strength 
                   
                   
                   
                   
                   
               
               
                 of Sheathing 
                   
                   
                   
                   
                   
               
             
          
           
               
                 Dry 
                 C-947 
                 psi 
                 ≧1800 
                 1400-3500 
                   
               
             
          
           
               
                 Wet 
                 C-947 
                 psi 
                 ≧1650 
                 1300-3000 
                   
               
               
                 AMOE of 
                   
                   
                   
                   
                   
               
               
                 Sheathing 
                   
                   
                   
                   
                   
               
               
                 Dry 
                   
                 ksi 
                 ≧700 
                  600-1000 
                   
               
               
                 Wet 
                   
                 ksi 
                 ≧600 
                 550-950 
                   
               
               
                 Screw 
                   
                   
                   
                   
                 (screw size: #8 
               
               
                 Withdrawal 
                   
                   
                   
                   
                 wire 1⅝ inch 
               
               
                   
                   
                   
                   
                   
                 screw with 0.25 
               
               
                   
                   
                   
                   
                   
                 inch diameter 
               
               
                   
                   
                   
                   
                   
                 head minimum) 
               
               
                 ½″ Panel- 
                 D-1761 
                 pounds 
                 352 
                 250-450 
                 Equiv. to American 
               
               
                 Dry 
                   
                   
                   
                   
                 Plywood Assoc. 
               
               
                   
                   
                   
                   
                   
                 (APA) S-4 
               
               
                 ½″ Panel- 
                 D-1761 
                 pounds 
                 293 
                 200-400 
                 % of force for SCP 
               
               
                 Wet 
                   
                   
                   
                   
                 relative to OSB 
               
               
                   
                   
                   
                   
                   
                 82%; % of force 
               
               
                   
                   
                   
                   
                   
                 for SCP relative to 
               
               
                   
                   
                   
                   
                   
                 Plywood 80% 
               
               
                 ¾″ Panel- 
                 D-1761 
                 pounds 
                 522 
                 450-600 
                 Equiv. to American 
               
               
                 Dry 
                   
                   
                   
                   
                 Plywood Assoc. 
               
               
                   
                   
                   
                   
                   
                 (APA) S-4 
               
               
                 ¾″ Panel- 
                 D-1761 
                 pounds 
                 478 
                 450-550 
                 % of force for SCP 
               
               
                 Wet 
                   
                   
                   
                   
                 relative to OSB 
               
               
                   
                   
                   
                   
                   
                 82%; % of force 
               
               
                   
                   
                   
                   
                   
                 for SCP relative to 
               
               
                   
                   
                   
                   
                   
                 Plywood 80% 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2B 
               
               
                   
               
               
                   
                 ASTM 
                   
                 Preferred 
                   
                   
               
               
                 Physical 
                 Test 
                   
                 Target 
                 Typical 
                   
               
               
                 Characteristics 
                 Method 
                 Unit 
                 Value 
                 Range 
                 Notes 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Lateral Screw 
                   
                   
                   
                   
                 Screw size: #8 wire 
               
               
                 Resistance 
                   
                   
                   
                   
                 1⅝ inch screw with 
               
               
                   
                   
                   
                   
                   
                 0.25 inch diameter 
               
               
                   
                   
                   
                   
                   
                 head minimum 
               
               
                 ½″ Panel- 
                 D-1761 
                 pounds 
                 445 
                 350-550 
                 Equiv. to APA S-4 
               
               
                 Dry 
                   
                   
                   
                   
                   
               
               
                 ½″ Panel- 
                 D-1761 
                 pounds 
                 558 
                 400-650 
                 % of force for SCP 
               
               
                 Wet 
                   
                   
                   
                   
                 relative to OSB 73; % 
               
               
                   
                   
                   
                   
                   
                 of force for SCP 
               
               
                   
                   
                   
                   
                   
                 relative to Plywood 
               
               
                   
                   
                   
                   
                   
                 82% 
               
               
                 ¾″ Panel- 
                 D-1761 
                 pounds 
                 414 
                 400-500 
                 Equiv. to APA S-4 
               
               
                 Dry 
                   
                   
                   
                   
                   
               
               
                 ¾″ Panel- 
                 D-1761 
                 pounds 
                 481 
                 400-500 
                 % of force for SCP 
               
               
                 Wet 
                   
                   
                   
                   
                 relative to OSB 73; % 
               
               
                   
                   
                   
                   
                   
                 of force for SCP 
               
               
                   
                   
                   
                   
                   
                 relative to Plywood 
               
               
                   
                   
                   
                   
                   
                 82% 
               
               
                 Static &amp; Impact 
                   
                   
                   
                   
                   
               
               
                 Test (¾ inch 
                   
                   
                   
                   
                   
               
               
                 thick SCP) 
                   
                   
                   
                   
                   
               
               
                 Ultimate 
                   
                   
                   
                   
                   
               
               
                 Static 
                 E-661 
                 pounds 
                 1286 
                 1000-1500 
                 APA S-1; 16 inch o.c. 
               
               
                   
                   
                   
                   
                   
                 Span Rating ≧550 lbs. 
               
               
                 Following 
                 E-661 
                 pounds 
                 2206 
                 1500-3000 
                 APA S-1; 16 inch o.c. 
               
               
                 Impact 
                   
                   
                   
                   
                 Span Rating ≧400 lbs 
               
               
                 Deflection 
                   
                   
                   
                   
                   
               
               
                 under 200 lb. 
                   
                   
                   
                   
                   
               
               
                 Load 
                   
                   
                   
                   
                   
               
               
                 Static 
                 E-661 
                 inches 
                 0.014 
                 0.010-0.060 
                 APA S-1; 16 inch o.c. 
               
               
                   
                   
                   
                   
                   
                 Span Rating ≦0.078″ 
               
               
                 Following 
                 E-661 
                 inches 
                 0.038 
                 0.020-0.070 
                 APA S-1; 16 inch o.c. 
               
               
                 Impact 
                   
                   
                   
                   
                 Span Rating ≦0.078″ 
               
               
                 Uniform Load 
                   
                   
                   
                   
                   
               
               
                 ¾″ Panel- 
                   
                 psf 
                 330 
                 300-450 
                 16 inch o.c. Span 
               
               
                 Dry 
                   
                   
                   
                   
                 Rating ≧330 psf 
               
               
                 Linear 
                   
                   
                   
                   
                   
               
               
                 Expansion 
                   
                   
                   
                   
                   
               
               
                 ½″ to ¾″ 
                 APA 
                 % 
                 ≦0.1 
                 ≦0.1 
                 APA P-1 requires ≦0.5% 
               
               
                 Panel 
                 P-1 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2C 
               
               
                   
               
               
                   
                   
                   
                 Preferred 
                   
                   
               
               
                 Physical 
                 ASTM Test 
                   
                 Target 
                   
                   
               
               
                 Characteristics 
                 Method 
                 Unit 
                 Value 
                 Typical Range 
                 Notes 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Water 
                   
                   
                   
                   
                   
               
               
                 Absorption 
                   
                   
                   
                   
                   
               
               
                 ½″ Panel 
                 APA 
                 % 
                 11.8 
                  7 to 15 
                 % water absorption of 
               
               
                   
                 PRP- 
                   
                   
                   
                 SCP relative to ½ inch 
               
               
                   
                 108 
                   
                   
                   
                 thick OSB: 51.5%, 
               
               
                   
                   
                   
                   
                   
                 % water absorption of 
               
               
                   
                   
                   
                   
                   
                 SCP relative to ½ inch 
               
               
                   
                   
                   
                   
                   
                 thick Plywood: 46.2% 
               
               
                 ¾″ Panel 
                 APA 
                 % 
                 10.8 
                  7 to 15 
                 % water absorption of 
               
               
                   
                 PRP- 
                   
                   
                   
                 SCP relative to 
               
               
                   
                 108 
                   
                   
                   
                 OSB: 51.3%, 
               
               
                   
                   
                   
                   
                   
                 % water absorption of 
               
               
                   
                   
                   
                   
                   
                 SCP relative to 
               
               
                   
                   
                   
                   
                   
                 Plywood: 48.1% 
               
               
                 Thickness 
                   
                   
                   
                   
                   
               
               
                 Swell 
                   
                   
                   
                   
                   
               
               
                 ½″ Panel 
                 APA 
                 % 
                 2.3 
                 1 to 5 
                 % water absorption of 
               
               
                   
                 PRP- 
                   
                   
                   
                 SCP relative to ½ inch 
               
               
                   
                 108 
                   
                   
                   
                 thick OSB: 22.2%, % 
               
               
                   
                   
                   
                   
                   
                 water absorption of 
               
               
                   
                   
                   
                   
                   
                 SCP relative to ½ inch 
               
               
                   
                   
                   
                   
                   
                 thick Plywood: 7.8% 
               
               
                 ¾″ Panel 
                 APA 
                 % 
                 2.4 
                 1 to 5 
                 % water absorption of 
               
               
                   
                 PRP- 
                   
                   
                   
                 SCP relative to 
               
               
                   
                 108 
                   
                   
                   
                 OSB: 22.2%, % water 
               
               
                   
                   
                   
                   
                   
                 absorption of SCP 
               
               
                   
                   
                   
                   
                   
                 relative to 
               
               
                   
                   
                   
                   
                   
                 Plywood: 7.8% 
               
               
                 Mold &amp; 
                   
                   
                   
                   
                   
               
               
                 Bacteria 
                   
                   
                   
                   
                   
               
               
                 Resistance 
                   
                   
                   
                   
                   
               
               
                 ½ to ¾″ 
                 G-21 
                   
                 1 
                 0 to 1 
                 OSB &amp; Plywood have 
               
               
                 Panel 
                   
                   
                   
                   
                 food source 
               
               
                 ½ to ¾″ 
                 D-3273 
                   
                 10 
                 10 
                 OSB &amp; Plywood have 
               
               
                 Panel 
                   
                   
                   
                   
                 food source 
               
               
                 Termite 
                   
                   
                   
                   
                   
               
               
                 Resistance 
                   
                   
                   
                   
                   
               
             
          
           
               
                 ½ to ¾″ 
                   
                   
                 No food 
                 No food 
                   
               
               
                 Panel 
                   
                   
                 source 
                 source 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
             
           
               
                 TABLE 2D 
               
               
                   
               
               
                   
                 ASTM 
                   
                 Preferred 
                   
                   
               
               
                 Physical 
                 Test 
                   
                 Target 
                 Typical 
                   
               
               
                 Characteristics 
                 Method 
                 Unit 
                 Value 
                 Range 
                 Notes 
               
               
                   
               
             
             
               
                 Horizontal 
                   
                   
                   
                   
                   
               
               
                 Design Shear 
                   
                   
                   
                   
                   
               
               
                 Capacity of the 
                   
                   
                   
                   
                   
               
               
                 Floor 
                   
                   
                   
                   
                   
               
               
                 Diaphragm 
                   
                   
                   
                   
                   
               
               
                 ¾″ Panel- 
                 E-455 
                 pounds 
                 487.2 
                 300-1000 
                 Performance relates 
               
               
                 10′×20′ 
                   
                 per 
                   
                 Typically 
                 to panel properties, 
               
               
                 Assembly 
                   
                 linear 
                   
                 400-800  
                 joist depth &amp; spacing 
               
               
                   
                   
                 foot 
                   
                   
                 and fastener type 
               
               
                   
                   
                   
                   
                   
                 and spacing 
               
               
                 System Fire 
                   
                   
                   
                   
                   
               
               
                 Resistance 
                   
                   
                   
                   
                   
               
               
                 ⅝ to ¾″ SCP 
                 E-119 
                 Time 
                 1 hr and 
                 1 to 1.5 hr 
                 Nominal 4″ deep 
               
               
                 Panel on one 
                   
                   
                 10 min. 
                   
                 stud, 24″ O.C., 
               
               
                 side of metal 
                   
                   
                   
                   
                 batt insulation, 1 
               
               
                 frame 
                   
                   
                   
                   
                 layer ⅝″ 
               
               
                   
                   
                   
                   
                   
                 FIRECODE Gypsum 
               
               
                   
                   
                   
                   
                   
                 Board available from 
               
               
                   
                   
                   
                   
                   
                 USG. 
               
               
                 ¾″ Panel 
                 E-119 
                 Time 
                 1.5 hr to 2 hr - 
                 1 to 2.5 hr 
                 Nominal 10″ deep 
               
               
                 SCP on one 
                   
                   
                 9 min 
                 or 
                 joist, 24″ O.C., 
               
               
                 side of metal 
                   
                   
                   
                 1 to 
                 batt insulation, 1 
               
               
                 frame 
                   
                   
                   
                 2.25 hr 
                 layer ⅝″ 
               
               
                   
                   
                   
                   
                   
                 FIRECODE Gypsum 
               
               
                   
                   
                   
                   
                   
                 Board available from 
               
               
                   
                   
                   
                   
                   
                 USG 
               
               
                 ¾″ Panel 
                 E-119 
                 Time 
                 1.5 hr to 2 hr - 
                 1.5 to 
                 Nominal 10″ deep 
               
               
                 SCP on one 
                   
                   
                 9 min 
                 2.5 hr 
                 joist, 24″ O.C., 
               
               
                 side of metal 
                   
                   
                   
                 or 
                 batt insulation, 2 
               
               
                 frame 
                   
                   
                   
                 1.5 to 
                 layer ⅝″ 
               
               
                   
                   
                   
                   
                 2.25 hr 
                 FIRECODE Gypsum 
               
               
                   
                   
                   
                   
                   
                 Board available from 
               
               
                   
                   
                   
                   
                   
                 USG 
               
               
                   
               
             
          
         
       
     
     Horizontal Design Shear Capacity in Table 2D provides for a safety factor of 3. 
     A typical ¾ inch (19 mm) thick panel when tested according to ASTM 661 and APA S-1 test methods over a span of 16 inches (406.4 mm) on centers, has an ultimate load capacity greater than 550 lb (250 kg), under static loading, an ultimate load capacity greater than 400 lb (182 kg) under impact loading, and a deflection of less than 0.078 inches (1.98 mm) under both static and impact loading with a 200 lb (90.9 kg) load. 
     Typically, the flexural strength of a panel having a dry density of 65 lb/ft 3  (1040 kg/m 3 ) to 90 lb/ft 3  (1440 kg/m 3 ) or 65 lb/ft 3  (1040 kg/m 3 ) to 95 lb/ft 3  (1522 kg/m 3 ) after being soaked in water for 48 hours is at least 1000 psi (7 MPa), e.g. 1300 psi (9 MPa), preferably at least 1650 psi (11.4 MPa) more preferably at least 1700 psi (11.7 MPa) as measured by the ASTM C 947 test. 
     Typically the horizontal shear diaphragm load carrying capacity of the system will not be lessened by more than 25%, preferably not be lessened by more than 20%, when exposed to water in a test wherein a 2 (5.1 cm) inch head of water is maintained over ¾ inch (1.9 cm) thick SCP panels fastened on a 10 foot by 20 foot (305×610 cm) metal frame for a period of 24 hours. 
     Typically the system will not absorb more than 0.7 pounds per square foot of water when exposed to water in a test wherein a 2 inch head of water is maintained over ¾ inch thick SCP panels fastened on a 10 foot by 20 foot (305×610 cm) metal frame for a period of 24 hours. 
     Typically an embodiment of the present system having a 10 foot wide by 20 foot (305×610 cm) long by ¾ inch thick diaphragm of the SCP panels attached to a 10 foot by 20 foot (305×610 cm) metal frame will not swell more than 5% when exposed to a 2 inch (5.1 cm) head of water maintained over the SCP panels fastened on the metal frame for a period of 24 hours. 
     Typically, the present reinforced SCP panel meets ASTM G-21 in which the panel achieves approximately a 1 and meets ASTM D-3273 in which the system achieves approximately a 10. Also, typically the present system supports substantially zero bacteria growth when clean. Also, typically the present system is inedible to termites. 
     Typically a non-combustible system for construction comprising: a shear diaphragm supported on metal frame, the shear diaphragm comprising the panel of the present invention and the frame comprising metal framing members, wherein the panel has a thickness of ¾ inch and has a racking strength ultimate load measured according to ASTM E72 racking from about 4400 to 7400 lbs. (1996 to 3357 kgs.) for an 8 foot by 8 foot wall assembly. This translates to a nominal wall racking shear strength of about 550 lbs per linear foot to 925 pounds per linear foot. For example, the racking strength ultimate load may be in the range of from about 4600 to about 6000 lbs. (2086 to 2721 kgs.) for an 8 foot by 8 foot wall assembly. This translates to a nominal wall racking shear strength of about 575 lbs per linear foot to 750 pounds per linear foot. The assembly for this ASTM E72 racking measurement is single sided and has 16 gage 3⅝ inch studs, 16 inches on center with fasteners 6 inches on center in the perimeter and 12 inches on center in the field. The panels for this ASTM E72 racking measurement are installed horizontally with no blocking in the cavities. The fasteners were #8-18×1⅝ inch long winged DRILLER BUGEL HEAD screws. 
     Values for wall racking strength can vary for different gauge studs, different stud spacing or different fastener spacing. Thus, a typical range for wall racking strength ranges from 500-7000 plf, nominal racking shear strength. 
     Wall Racking Strength is expressed in pounds per lineal foot, the ultimate load for a test specimen can be expressed as the max load on the test specimen as an entire unit, or in an ultimate load expressed in pounds per lineal foot, e.g., the width of the specimen. 
     Typically, the panel when fastened to wall framing has racking shear strength between 1.1 and 3.0 times the racking shear strength of a similar dimensioned (sized) SCP panel without reinforcing fastened to the same wall framing with the same fasteners. 
     EXAMPLES 
     Test Specimen Diaphragm Materials 
     Prototype ¾″ SCP—Structural Cement Panel of the present invention reinforced with fiberglass strands. A “V”-groove and tongue is located along the 8′ dimension of the 4′×8′ (122×244 cm) sheets. The formulation used in the SCP panel examples of this floor diaphragm test is listed in TABLE 3. 
     
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                 Ingredient 
                 Weight Percent (%) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Reactive Powder Blend 
                   
               
               
                   
                 Portland Cement 
                 29 
               
               
                   
                 Calcium Sulfate Alpha Hemihydrate 
                 58 
               
               
                   
                 Silica Fume 
                 12 
               
               
                   
                 Lime 
                 1 
               
               
                   
                 SCP Cementitious Composition 
                   
               
               
                   
                 Portland Cement 
                 12.2 
               
               
                   
                 Calcium Sulfate Alpha Hemihydrate 
                 24.4 
               
               
                   
                 Silica Fume 
                 5.1 
               
               
                   
                 Lime 
                 0.4 
               
               
                   
                 Ceramic Microspheres 
                 27.4 
               
               
                   
                 Superplasticizer 
                 1.9 
               
               
                   
                 Water 
                 24.2 
               
               
                   
                 Alkali-Resistant Glass Fibers 1   
                 4.4 
               
               
                   
               
               
                   1 Weight proportion corresponds to 1.8% volume fraction of Alkali Resistant Glass Fibers in the composite. 
               
               
                 Length of glass fibers used in the floor diaphragm test - 36 mm. 
               
             
          
         
       
     
     A total of 5 panels were tested. Each panel consisted of the same framing detail (16 ga 3⅝″ (9.2 cm) studs manufactured by Dietrich located 16″ (40.6 cm) on center), fastener layout (6″ (15.2 cm) on center on the perimeter, 12″ (30.5 in the field) and ¾″ SCP panels were all installed horizontally with no blocking in the cavities. All of the assemblies were single sided. 
     Panel  1  is the base case with no additional metal reinforcement added. 
     Panel  2  had a full sheet (4′×8′) (122×244 cm) piece of 22 gauge steel bonded to the back side. 
     Panel  3  had 8″ (20.3 cm) wide strips of 22 gauge steel bonded along the 8′ dimension of the panel (similar to the embodiment of  FIG. 5 ). The reinforcements of Panels  3 - 5  are glued to the surface of the panel to protrude from the panel surface. 
     Panel  4  had 18″×18″ (46×46 cm) gussets bonded to all four corners of each SCP panel (similar to the embodiment of  FIG. 10 , but the reinforcements protrude and there are no reinforcing members  56 ). 
     Panel  5  had 18″×18″ (46×46 cm) gussets with folded over edges bonded to all 4 corners of each SCP panel (similar to Panel  4  but the gussets having folded over edges). 
     The ultimate loads measured according to ASTM E72 racking were as follows (number in square brackets are the correlating indices): 
     Panel  1 —4147 lb (1881 kg) [1] 
     Panel  2 —7651 lb (3470 kg) [1.845] 
     Panel  3 —5641 lb (2558 kg) [1.360] 
     Panel  4 —4712 lb (2137 kg) [1.136] 
     Panel  5 —3828 lb (1736 kg) [0.923] 
     The failure modes for each panel were as follows: 
     Panel  1 —fastener pull through around the perimeter 
     Panel  2 —fastener pull through/shear around the perimeter. Metal unbonded and buckled on backside. 
     Panel  3 —fastener pull through/shear around the perimeter. Metal unbonded and buckled on backside. 
     Panel  4 —fastener pull through/shear around the perimeter. Metal unbonded and buckled on backside. Adhesive appeared not to be fully cured and still wet to the touch after test. 
     Panel  5 —fastener shear around the perimeter initially then bending pull out of fasteners. Metal unbonded and buckled on backside. It should be noted here that due to the bent portion of the gusset that a 3/16″ space was present along the horizontal joint of the assembly. This will adversely affect the performance. 
       FIG. 34  shows ASTM E72 Racking of these five 8 foot×8 foot samples with SCP installed horizontally on 16 gage 3.624 steel studs at 16 inches on center with fastener layout of 6″ (15.2 cm) on center on the perimeter and 12″ (30.5 cm) in the field. 
     While a particular embodiment of the system employing a horizontal diaphragm of fiber-reinforced structural cement panels on a metal frame has been shown and described, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.