Abstract:
A method to create a precast concrete module includes: pouring the foundation; placing a welded wire mesh reinforced polystyrene panel into a wet mix; allowing the mix to partially set up, and pouring the top of the slab; installing wall and roof panels and mechanically attaching them with welded wire mesh; installing electrical and plumbing prior to placing concrete forms; placing the forms and pouring concrete mix into the forms; and wrecking the forms and finishing out the module.

Description:
CROSS REFERENCE To RELATED APPLICATION 
       [0001]    The present application is related to and claims priority of U.S. provisional patent application (“Copending Provisional Application”), Ser. No. 61/989,940, entitled “PRECAST CONCRETE MODULE”, filed on May 7, 2014. The Copending Provisional Application is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is related to building methods, and, more particularly, to a method of fabricating a six-sided concrete module, and also to retrofitting existing structures with the six-sided concrete module or modules in order to create a safe room or storm shelter. 
       BACKGROUND OF THE INVENTION 
       [0003]    Six-sided concrete modules are known in the art. However, previous methods included casting panels either horizontally or vertically and then mechanically attaching the panels together at a later time, which resulted in an overall weak structure. What is desired, therefore, is an enhanced fabrication method wherein all of the walls and the ceiling or roof of the structure are cast together in a monolithic pour that better ties the structure together to form a stronger concrete module. 
       SUMMARY OF THE INVENTION 
       [0004]    According to an embodiment of the present invention, a fabrication method for providing a six-sided concrete module includes a structural wire reinforced insulating polystyrene panel that is mechanically attached with welded wire mesh on both primary sides of the panel. The minor sides of the panel are also wrapped with mesh prior to pouring or injecting the concrete mix into the forms or molds. The polystyrene panels range in thickness from 1.5″ to 10″. The thicker panels have added insulating value, and also strengthen the wall sections as the structural concrete facing is spaced further apart. 
         [0005]    The method of the present invention uses high-strength light-weight cellular concrete mixes that range from 4,000 psi to 20,000 psi. Whereas standard concrete weighs approximately 150 lbs per cubic foot, the mix used for the present invention ranges from about 90 lbs to 120 lbs per cubic foot. The concrete is reinforced with high strength helical-shaped metal fibers. The helical fibers used for concrete mixes in the present invention are about 25 mm in length, have a diameter of about 0.50 mm (0.02 in), a weight of about 11,500 fibers per pound, have a tensile strength of about 246.5 ksi minimum, are made of high carbon steel, and are electroplated with zinc. Reinforcement in this fashion allows the fibers to come under tension as soon as the concrete exhibits micro-cracks. This gives the concrete higher ductile strength than conventional rebar or mesh-reinforced concrete. The special helical shaped fibers allow the concrete mix have a 200% increase in ductile strength when measured with respect to conventionally reinforced concrete. The cellular concrete mix is made lighter and stronger by adding a foaming agent to the mix, which creates “thick-skinned” bubbles. The bubbles act as tiny ball bearings, which improve movement and finishing, cracking, pitting, and bleeding. The bubbles also act similarly to a strong honeycomb, as the cement and water form chemical bonds forming cells walls in the matrix structure. As the concrete cures, the water is slowly released from the bubbles into the concrete—a benefit referred to as internal curing. The bubbles also have an effect of creating specific-sized bubbles in the concrete, which gives the concrete insulating properties while also decreasing the weight of the concrete. 
         [0006]    The method of the present invention also uses monolithic casting. The method and system of the present invention can be used to cast complete six-sided concrete modules, or retrofitted into existing structures to create a safe room, storm shelter, or other such structures. The safe rooms and shelters can be designed to withstand blast pressure up to 12 psi. This is accomplished by strengthening the concrete mix, widening the concrete cross-section of the system, and/or spacing the structural concrete panels further apart from each other separated by the foam core. 
         [0007]    The precast concrete modules created using the system and method of the present invention have many uses. The six-sided modules are fully independent of each other and can therefore be used in a stand-alone application to create a safe room, cabin, guard shack, one room dwelling, or other high-valued asset protective structure. The six-sided modules can be placed together both horizontally and vertically to create single and multi-family housing, hotels, barracks, offices, schools, storages units/facilities, as well as other such structures. The six-sided precast concrete modules according to the present invention are energy efficient, blast resistant, bullet resistant, tornado resistant, fire resistant, and earthquake resistant all due to the specialized way that the concrete is reinforced with both welded wire mesh and helical-shaped metallic reinforcement that is mixed integrally with the high-strength concrete. The concrete modules of the present invention are very strong structurally, but also are light in weight than if they were cast with conventional, non-cellular concrete. The fabricated units have high energy efficient values due to the use of insulating polystyrene panels and the cellular concrete mix. 
         [0008]    The manufacturing steps used to create a precast concrete module according to the present invention include: pouring the foundation; placing a welded wire mesh reinforced polystyrene panel into a wet mix, or pouring mix partially up to a structural panel that is placed prior to placing concrete; allowing the mix to partially set up, and pouring the top of the slab either before wall panels are attached to the pre-placed wire mesh, or after; installing wall and roof panels and mechanically attaching them with welded wire mesh; installing any electrical, plumbing, or other design-required provisions prior to placing the concrete forms; placing the forms and pouring or injecting concrete mix into the forms; and wrecking the forms and finishing out the modules. 
         [0009]    As described above, the six-sided concrete modules of the present invention can be used to retro-fit an existing structure. The procedures and steps to retro-fit an existing structure to include a strong-built safe room or storm shelter according to the present invention include; designing a safe room to existing room dimensions and design loads; making any provisions to strengthen existing walls to handle the hydrostatic loads of the concrete mix; drilling holes to accept rebar for mechanically attaching walls to an existing concrete foundation; epoxying the rebar in holes using high-strength epoxy per design; placing reinforced polystyrene wall panels and attaching to the rebar placed in the concrete foundation (offset panels from existing interior walls to the required distance are used to allow a designed concrete cross-section to be cast between the panel and the existing wall); attaching reinforced polystyrene roof panels and mechanically fastening panels to each other per design (ensure that the roof panel is properly spaced from the existing ceiling to allow proper concrete thickness between the panel and the existing ceiling per the engineer design); making holes in the polystyrene panels to allow equal flow of the concrete mix on each side of the panels and air to escape as mix is injected into the forms; drilling holes through the existing ceiling to allow air to escape as concrete mix is injected into the forms; forming interior walls and ceiling; injecting high strength helical fiber mix into the forms until the mix fills drilled holes in existing ceiling/floor above the new safe room or storm shelter; and stripping and wrecking the concrete forms after the mix has properly cured. 
         [0010]    The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of an embodiment of the invention as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1A  is a cutaway view of a complete portion of a wall or ceiling showing two sets of wire mesh panels attached together through the insulating core, along with the inner and outer concrete portions according to an embodiment of the present invention; 
           [0012]      FIG. 1B  is a cross-sectional view of a welded wire polystyrene panel according to an embodiment of the present invention; 
           [0013]      FIG. 1C  is a cutaway view of a complete portion of a wall or ceiling showing two sets of wire mesh panels attached together through the insulating core, along with the inner and outer concrete portions according to an additional embodiment of the present invention; 
           [0014]      FIG. 1D  is a cross-sectional view of a welded wire polystyrene panel according to an additional embodiment the present invention; 
           [0015]      FIGS. 2-10  are cross-sectional views to the steps used to create a six-sided module according to the present invention; 
           [0016]      FIG. 11  is a cross-sectional view of retro-tit embodiment of the present invention; and 
           [0017]      FIG. 12  is shows the completed concrete structure with openings for a door and windows according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Referring now to  FIG. 1A  a portion of a wall or ceiling is shown according to the present invention. The wall portion shown in  FIG. 1A  includes an outer 2″ by 2″ welded wire mesh panel  10 A and an inner 2″ by 2″ welded wire mesh panel  10 B. An insulating core  14 , typically Type 1 modified expanding polystyrene, is placed between the two wire mesh panels  10 A and  10 B. The two wire mesh panels  10 A and  10 B are electro-welded together with wire members  12  through the polystyrene core  14 . The wall portion shown in  FIG. 1A  also includes an outer concrete portion  16 A formed of high strength, light-weight cellular concrete, reinforced with helical-shaped, steel micro-reinforcement fibers.  FIG. 1A  also includes an inner concrete portion  16 B also formed of high strength, light-weight cellular concrete, reinforced with helical-shaped, steel micro-reinforcement fibers  17 .  FIG. 1B  shows the wall portion, except for the concrete portions, in a cross-sectional view, which is also referred to as a welded wire mesh polystyrene panel  18 .  FIG. 1B  shows the two welded wire mesh panels  10 A and  10 B coupled together with wire members  12 . The polystyrene core  14  is shown located between the wire mesh panels  10 A and  10 B intersected by the wire members  12  coupling the wire mesh panels  10 A and  10 B. 
         [0019]    The embodiment of  FIG. 1C  is substantially the same as the embodiment of  FIG. 1A , and the same reference numerals are used for the same elements. However, note that the wire members  12  are angled with respect to the wire mesh panels  10 A and  10 B. The wire members  12  still extend through the insulating core  14 . Similarly, Figure ID substantially corresponds to  FIG. 1B , previously described. Note again that the wire members  12  arc angled with respect to wire mesh panels  10 A and  10 B, but still extend through the insulating core  14  as shown. 
         [0020]      FIG. 2 through 10  illustrate the steps used to create a six-sided concrete module according to the present invention, in cross-sectional views. 
         [0021]    Referring now to  FIG. 2 , concrete forms  20 A and  20 B are set to form the floor of the concrete module as shown. 
         [0022]    Referring now to  FIG. 3 , the floor  15  is partially formed. Concrete is poured to approximately one-third of the level of the concrete forms  20 A and  20 B. A high-strength, light-weight cellular concrete is used, reinforced with helical-shaped steel micro-reinforcement fibers as described above. 
         [0023]    Referring now to  FIG. 4 , a welded-wire mesh polystyrene panel  18 A and two connectors  40 A and  40 B are submerged into the wet concrete. Note that the connectors  40 A and  40 B are tied to the welded wire mesh polystyrene panel  18 A to form a complete assembly as shown. 
         [0024]    Referring now to  FIG. 5 , welded wire mesh polystyrene wall panels  18 C and  18 D are added to the assembly, using connectors  40 C and  40 D. Connectors  40 C and  40 D are tied to the existing assembly comprising panels  18 A,  18 C, and  18 D. The remaining two-thirds of the concrete to the levels of the concrete forms  20 A and  20 B is poured, thus completing the floor  15  of the concrete module. 
         [0025]    Referring now to  FIG. 6 , after the floor  15  hardens, the ceiling panel  18 B is installed using additional connectors  40 E,  40 F,  40 G, and  40 H. All of these connectors are tied into the assembly as shown. New concrete forms  20 A′,  20 B″,  20 C,  20 D, and  20 E are installed that will be used to create the completed walls and ceiling. 
         [0026]    Referring now to  FIG. 7 , the remaining concrete is poured to complete the walls and the ceiling of the concrete module. 
         [0027]    Referring now to  FIG. 8 , after the concrete hardens, the forms are removed to reveal the finished structure included the floor  15 , walls  60 A and  60 B, and ceiling  70 . All of the structural elements encapsulate the polystyrene panels  18 A,  18 B,  18 C, and  18 D, as well as the connectors  40 A,  40 B,  40 C,  40 D,  40 E,  40 F,  40 G, and  40 H as shown. While the six-sided concrete module is shown in cross-sectional form in  FIG. 8 , it will be appreciated by those skilled in the art that the entire structure can be translated into three dimensions to include two additional walls. 
         [0028]      FIGS. 9 and 10  show optional electrical and plumbing fittings that can be installed before the concrete is poured. 
         [0029]    Referring now to  FIG. 9 , after all of the welded wire mesh polystyrene panels and connectors have been installed and wired together, but before the concrete is poured, optional conduits and boxes for electrical, lighting, outlets, switches, and the like can be installed.  FIG. 9  shows, for example, electrical box  50  that can be used for lighting, electrical box  52  for switching, conduit  54  for running wires, and electrical box  56  that can be used for an outlet. Other configurations can be used as known by those of skill in the art. 
         [0030]    Referring now to  FIG. 10 , after all of the welded wire mesh polystyrene panels and connectors have been installed and wired together, but before the concrete is poured, optional plumbing for hot and cold water, toilets, sinks, drains, and the like can be installed.  FIG. 10  shows, for example, a water feed pipe  60  that can be used for an appliance such as a sink, and a water drain pipe  62  that can also be used for an appliance such as a sink. Other configurations can be used as known by those of skill in the art. 
         [0031]    Referring now to  FIG. 11 , a retro-fit embodiment of the present invention is shown. In the retro-fit embodiment, the method of the present invention proceeds substantially as previously described with minor adjustments as described below. Concrete forms  87 A,  87 B, and  87 C are installed inside of an existing room to form walls and a ceiling using the existing walls  80 A and  80 B as shown. An exterior brace  86  or braces may be required to strengthen the existing walls during concrete pouring. Rebar dowels  82 A,  82 B,  82 C,  84 A,  84 B, and  84 C are epoxied into the existing floor slab  88 . Welded-wire mesh polystyrene panel  89 A is wired or otherwise coupled to rebar dowels  82 A,  82 B, and  82 C as shown. Welded-wire mesh polystyrene panel  89 B is wired or otherwise coupled to rebar dowels  84 A,  84 B, and  84 C as shown. Once the structure shown in  FIG. 11  has been completed, concrete can be poured as before. Holes may have to be drilled into the existing ceiling to provide access for the poured concrete. Note in  FIG. 11  that part of the polystyrene core of panels  89 A and  89 B may have to be removed at location  85 A and  85 B as required for attachment to the rebar dowels as shown. Electrical and plumbing provisions can be made as previously described. 
         [0032]    Referring now to  FIG. 12 , the completed concrete structure  93  is shown with window and door openings. Window openings  92 A,  92 B, and  92 C are shown. Door opening  90  is also shown. Window and door openings can be obtained using additional forms or frames as is known in the art. 
         [0033]    While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various other changes in the form and details may be made without departing from the spirit and scope of the invention. It should be understood that this description has been made by way of example, and that the invention is defined by the scope of the following claims.