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CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/357,739, filed Feb. 16, 2002. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    1. Field of the Invention  
           [0004]    This invention relates generally to lightweight composite concrete, and particularly to a method for the fabrication of buildings and building elements therewith.  
           [0005]    2. Description of the Related Art  
           [0006]    Concrete has historically been a material of choice for construction of buildings due to the ability to form the concrete, its strength and durability. Use of concrete in the construction of modular buildings is limited by various factors—two of the significant factors being the weight of the concrete and the limitations of flowability of the concrete.  
           [0007]    Specifically, when building wall elements are relatively tall, molds for such walls must be correspondingly deep making it difficult to construct a modular concrete structure that can be economically transported and that maintains sufficient strength and durability. Historically, increased flowability has required an increased proportion of water in the concrete mixture resulting in reduced strength of the resulting product.  
           [0008]    Various formulations have been developed to improve the weight to volume ratio of concrete, including various concrete additives (or admixes) and aggregate materials added in varied order. The use of polystyrene as an aggregate is known in the field to reduce weight and add insulating properties to concrete; however, past uses have experienced difficulty with separation of the polystyrene from the mix and penetration of the mix into deep forms. Prior uses have addressed this problem by pouring the forms in a horizontal orientation, so the forms are only as deep as the thickness of the item poured. Once sufficiently cured, the resulting wall component may be rotated into a vertical position. This method, however, does not permit the creation of integrated wall components that are not co-planar, since only one wall could be put into a horizontal position at a time. The separate components may be assembled at intended angles after curing, but such assembled angles do not provide the stability and durability of integrally poured components.  
           [0009]    It would be an improvement to the art to develop a composite concrete that freely flows to uniformly fill all the spaces of a deep form containing internal components. In standard concrete, increased flowability of concrete has required addition of water with a significant reduction of concrete strength.  
           [0010]    Various methods of forming modular, mobile concrete structures are known. Generally, pre-formed concrete structures involve forming sections, transporting such sections to a construction site and assembling the sections at the construction site. Because of the weight of concrete and forming limitations, such as the formation of angles discussed above, concrete sections are generally planar units or a planar unit with extending connection elements.  
           [0011]    It would be an improvement to the prior art to provide a method of constructing modular concrete buildings or components thereof that are formed as integral units, with the integral unit including complete building sections and incorporating various building elements, such as windows, doors, electrical conduits and piping. It would be a further improvement to the prior art to construct such units of a relatively lightweight, insulating concrete having substantial strength and durability formed in an orientation ready for use.  
           [0012]    Accordingly, objects of the present invention are to provide:  
           [0013]    a method of constructing modular, mobile buildings and building components of a concrete type material;  
           [0014]    a material for use in construction of modular, mobile buildings and building components.  
           [0015]    Other objects of my invention will become evident throughout the reading of this application.  
         BRIEF SUMMARY OF THE INVENTION  
         [0016]    The present invention provides a method and apparatus for constructing concrete building units and a concrete mixture for use with such method and apparatus. A concrete mixture includes a defined combination of cement, sand, water, polystyrene beads, wire fibers or fiber mesh, and a conditioning concrete additive to provide free-flowing properties when wet and a stable, lightweight cured product. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a perspective end view of a floor form.  
         [0018]    [0018]FIG. 2 is a side view of an internal form.  
         [0019]    [0019]FIG. 3 is a side view of a section of an internal form with internal wall elements in place.  
         [0020]    [0020]FIG. 4 is a side view of an entire double internal form with internal wall elements in place.  
         [0021]    [0021]FIG. 5 is a perspective view of an internal form nesting into a form shell.  
         [0022]    [0022]FIG. 6 is a perspective view of completed structures removed from the internal form and external form shell.  
         [0023]    [0023]FIG. 7 is an end view of a bracing unit positioned in an internal form.  
         [0024]    [0024]FIG. 8 is a cut-away side view of the bracing unit within an internal form.  
         [0025]    [0025]FIG. 9 is a perspective view of an alternate external form shell. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0026]    Referring first to FIGS. 1, 2 and  6 , the exemplary process of the present invention for constructing an integrated structure  100  using composite concrete starts with assembling the form for the floor. A platform  12  is prepared as the base for the structure floor. Platform  12  is raised above the ground by spacers  14  so that it can be subsequently moved. A floor frame  16  is assembled around platform  12 , frame  16  being sufficiently high to define the thickness of the structure floor  102 .  
         [0027]    Referring to FIGS. 1, 2,  3  and  6 , rebar  18  is installed in the area above platform  12  and within frame  16 . Upwardly extending segments of rebar  18  from floor  102  are provided in appropriate peripheral areas to tie into structure walls  104  and rear wall  108  subsequently in the process. Rebar  18  installation is in accordance with industry practice. The term rebar is used to refer to internal support and joining members integral to the cured floor, walls and ceiling. Additionally, any drains, pipes or openings (not shown) to be provided in the structure floor  102  are installed or framed on platform  12 .  
         [0028]    Floor frame  16  has curb frames  15  along two opposing sides, which correspond to structure walls  104  in the completed integrated structure  100 . Curb frame support  13  holds curb frame  15  in a position above horizontal rebar  18 , so the bottom of curb frame  15  is at the intended level of the top of structure floor  12 . Curb frame support  13  holds curb frame  15  in a position inside upwardly extending segments of rebar  18  so that the side of curb frame  15  facing adjacent upwardly extending segments of rebar  18  defines the interior surface of curb  103 . Rebar  18  has a continuous route between floor  12  and curb frame  15  and between floor frame  16  and curb frame  15  from the horizontal orientation to the vertical orientation. Areas of curb  103  may be partitioned off under curb frame  15  in order to form structure separations  101  and door sills  105 .  
         [0029]    When floor frame  16  is assembled with the rebar  18 , a quantity of concrete (not shown) is poured within frame  16  on platform  12 . In the exemplary embodiment, a prior art concrete mixture is used to create floor  102 . Concrete handling methods known to the field are used to pour the concrete into the form and the wet concrete mixture is leveled and textured as desired to provide a suitable floor surface. The floor is allowed to cure.  
         [0030]    Referring to FIGS. 6 and 7, floor  102  is framed and constructed with curb  103  extending upwardly from a portion of the perimeter of floor  102 .  
         [0031]    Referring to FIG. 2, a side view of interior wall form  22  for wall  104  construction is depicted. Generally, form  22  is an elongated cube, consisting of two vertical sides, one horizontal top section, and one vertical end section perpendicular to both vertical sides  24  and top section  26 . Form  22  has interior dimensions equivalent to the desired exterior dimensions of the finished structure  100 . In the exemplary embodiment, interior wall form  22  is a double wall form for forming two modular units at the same time. Form  22  may be made with additional extensions in order to simultaneously form multiple modular units at a single time, limited by practicality, space and the quantity of concrete needed to pour all of the structures.  
         [0032]    Upon sufficient curing of floor  102  of the structure  100 , the frames  16  are removed from platform  12  and form  22  is positioned on the floor  102 . The peripheral upwardly extending rebar  18  extends upwardly from curb  103 .  
         [0033]    Referring to FIG. 3 and  6 , window frames  64  and doorframes  66  are arranged on form  22  at desired locations. Rebar  18  is placed on form  22  with spacers to space the rebar  18  from form  22  so that rebar  18  is interior of the finished structure wall  104 . Electrical conduit  68 , gas pipes (not shown), water pipes (not shown) and other structures or openings desired in the structure wall  104  are inserted or framed on exterior of form  22 .  
         [0034]    As depicted in FIG. 4 and  6 , one form  22  may be used to define the interior surface of walls  104  of a plurality of structures  100 . As depicted in FIGS. 3, 4 and  6 , wall end forms  28  are provided to define ends of structure walls  104 .  
         [0035]    As also indicated in FIGS. 3, 4 and  5 , rebar  18 , as installed, extends upward from floor  102  outside form  22  and over the upper edge of form  22  onto ceiling  106  of structure  100 . Floor rebar  18  is integrated with wall and ceiling rebar  18  exterior of form  22 .  
         [0036]    Referring to FIG. 5 and  6 , form shell  30  provides the exterior form for the creation of structure walls  104 . Form shell  30  comprises a plurality of shell walls  32 . A plurality of frame upper members  34  may also be present to provide rigidity. Shell  30  is so sized in relation to form  22  that the exterior of form  22  and the interior of shell  30  define the interior and the exterior, respectively, of walls  104  of the structure  100 . In the exemplary embodiment, form shell  30  is comprised of two shell walls  32  and a plurality of frame upper members  34 . A rear wall (not shown) may also be present, such that three walls of a rectangular house may be formed at once.  
         [0037]    Shell  30  is open at the top to allow for pouring of concrete material of the structure ceiling  106 . As with forming floor  102  and walls  104 , any conduits or pipes required in structure ceiling  106  are placed on form  22  top.  
         [0038]    In arranging shell  30  in relation to form  22 , an exemplary method is to provide shell  30  as a relatively fixed structure and to slide form  22 , including floor  102  and platform  12  into shell  30 , as partially depicted in FIG. 5. An exemplary method to move the floor  102 , platform  12  and form  22  is a compressed air lift system; however, various other methods are readily available, including wheeled mechanisms, tracks and the like. Floor  102  may be removed from platform  12 , when floor  102  is sufficiently cured, and moved by various methods known to the field.  
         [0039]    Upon full insertion of form  22  into shell  30 , wall end forms  28  should fit closely with corresponding interior surfaces of shell  30 . Accordingly, floor  102  wall end forms  28 , form  22  and shell  30  define at least two walls  104  of the structure  100 . Additionally, window frames  64  and doorframes  66  are arranged to fit closely with corresponding interior surfaces of shell  30 . A ceiling endpiece  36  is attached to form end to define an end of ceiling  106  of the structure  100 .  
         [0040]    In FIGS. 7 and 8, a bracing unit  70  is installed into the inner cavity of form  22  from the open end. The bracing unit  70  is moved with airlift or rolled into position. Once in position, bracing unit  70  rests on lifting legs  71 . Lifting legs  71  are extendable and are extended until the bracing unit raises form  22  to the desired height in shell  30 , to create the proper height to ceiling  106 . Form  22  is raised off floor  102 , but not higher than curb  103 . Once the proper height is attained, side expanders  74  extend to push static braces  72  of bracing unit  70  against one side of form  22 , and bracing wall  76 , on the other side of bracing unit  70  against the other side of form  22 .  
         [0041]    Upon bracing form  22  into shell  30 , concrete material may be poured in the cavity defined by form  22  and shell  30  to form walls  104  of the structure  100  (not shown in FIG. 5) and further to create the structure ceiling  106 . The concrete mixture of the present invention is handled generally the same as conventional concrete; however, due to the properties of the material, commonly used methods of rodding or vibrating the concrete mixture during the placement is not required.  
         [0042]    After the concrete material hardens sufficiently, the formed structure  100  may be removed from form  22  and shell  30 . As an alternative to bracing unit  70 , internal braces  38  may be provided within form  22 . Upon curing of the concrete material, the internal braces  38  or bracing unit  70  are removed, and sections of form  22  are removed from within the structure walls  104  and ceiling  106 . Internal braces  38  are schematically depicted in FIG. 5.  
         [0043]    A plurality of lifting eyes  52  are inserted into the concrete mix while wet to allow ready lifting of the finished structure  100 . The lifting eyes  52  allow the structure  100  to be moved and loaded onto trucks or railcars by cranes. Lifting eyes  52  are a permanent part of the structure  100 , so movement techniques and the necessary equipment can easily be anticipated, and provide for multiple movements of the structure  100 .  
         [0044]    Connectors  54  may also be formed into the floor  102 , wall  106  and ceiling  106  segments to allow for connection of structure ends as necessary or to allow for connection of various structures  100  with each other. The open wall of structure  100  may be closed off by connecting a separate wall piece (not shown) formed by methods known to the field. The separate wall piece may have a decorative to present a desirable building front appearance.  
         [0045]    The process described above can be practiced to construct a structure with three walls  104  by providing a form  22  end proximate an end of shell  30  or can be practiced to construct a structure  100  with both ends open. The process described above can be further practiced to construct interconnecting structures  100 .  
         [0046]    After the structures  100  are adequately cured, structures  100  are ready for finishing. The present concrete mixture provides a relatively uniform, relatively smooth surface for finishing.  
         [0047]    A typical wall  104  thickness of a structure  100  of the present invention is 5 inches (12.7 cm). The present invention may be practiced to construct structures  100  with wall widths from about 3 inches (7.62 cm) and wider. With rebar  18 , window frames  64 , door frames  68 , conduit  68  and various piping and other inserts, there are many areas of volume defined by form  22  and shell  30  that conventional concrete would not reach when poured from above according to the method of the present invention.  
         [0048]    Referring to FIGS. 9 and 6, in an alternate configuration, shell walls  132  are independent moveable structures, vertically anchorable to the ground a set distance apart. Shell walls  132  can be set into place to encase three sides of form  22  and define structural walls  104  and rear wall  108 , and then removed to release a newly formed structure  100 . In the exemplary embodiment, shell walls  132  are attached to a base work site by hinges  135  such that walls  132  may be rotated about the horizontal axis of hinges  135 . Platform  12  and form  22  fit between shell walls  132 , such that when shell walls  132  are arranged in a vertical position, the interior of shell side walls  134  and the exterior of form  22  define an area volume to form walls  104 . A shell rear wall  138  may be employed in order to permit the simultaneous formation of a rear wall  108 , where the interior of shell rear wall  138  and the exterior of form  22  define an area volume to form rear wall  108 .  
         [0049]    A flowable, relatively lightweight concrete mixture is required to practice the method of the present invention.  
       EXAMPLE I  
       [0050]    A concrete mixture and method capable of providing a concrete product with acceptable flow and strength characteristics comprises:  
         [0051]    Cement=70 lbs (26.13 kg)  
         [0052]    Sand=130 lbs (48.52 kg)  
         [0053]    Water=27 lbs (10.08 kg)  
         [0054]    Polystyrene Beads=1 cubic foot (0.028 cubic meters)  
         [0055]    Fiber Mesh (Fiber Mesh®)=12 lbs (4.48 kg)  
         [0056]    Admix (Glenium® 3030 NS)=7 oz (207.01 ml)  
         [0057]    Add 70% of the water to a suitable receptacle. Add all of the sand, and mix until the sand is wet and the mixture is flowable. Add all of the cement and continue to mix. Next, add all of the fiber mesh, then all of the polystyrene beads. Continue to mix, adding the remaining 30% of water. Finally, add the admix. When cured, the mixture produces a solid concrete weighting 86.8 pounds per cubic foot (1079.6 kilograms per cubic meter). Total volume of the mixture may be increased, but the proportional relationships and the addition sequence and process must still be followed.  
       EXAMPLE II  
       [0058]    A second concrete mixture and method capable of providing a concrete product with acceptable flow and strength characteristics comprises:  
         [0059]    Cement=70 lbs (26.13 kg)  
         [0060]    Sand=130 lbs (48.52 kg)  
         [0061]    Water=26.5 lbs (9.89 kg)  
         [0062]    Polystyrene Beads=1 cubic foot (0.028 cubic meters)  
         [0063]    Metal Fiber (Wiremix® W50)=12 lbs (4.48 kg)  
         [0064]    Admix (Glenium® 3030 NS)=5 oz (147.87 ml)  
         [0065]    Add 70% of the water to a suitable receptacle. Add all of the sand, and mix until the sand is wet and the mixture is flowable. Add all of the cement and continue to mix. Next, add all of the metal fiber, then all of the polystyrene beads. Continue to mix, adding the remaining 30% of water. Finally, add the admix. When cured, the mixture produces a solid concrete weighting 98.8 pounds per cubic foot (1228.86 kilograms per cubic meter). Total volume of the mixture may be increased, but the proportional relationships and the addition sequence and process must still be followed.  
         [0066]    Various forms of fiber mesh and metal fibers can be used in the mixture. Combinations of the two can also be used. In some instances it is appropriate to exclude rebar from the forms, if the fiber mesh and/or metal fiber combinations provides enough support for the particular application. The specific admixture used is Glenium® 3030NS, a polycarboxylate admix. Other admixes having similar properties may be used in appropriate concentrations. The concrete mixture provides improved thermal insulating properties over conventional prior art concrete.  
         [0067]    The foregoing drawings, discussion, and description of the invention is illustrative and explanatory, but are not meant to be limitations on the practice thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.

Summary:
A method for constructing concrete building units comprises forming and pouring a concrete floor on a floor platform, providing interior wall forms on said concrete floor, providing door frames, conduit and piping on said interior wall forms, providing a ceiling form; transporting said floor platform and floor intermediate spaced exterior wall forms, and pouring a concrete mixture in the wall opening intermediate the interior wall forms and the exterior wall forms. A free-flowing concrete mixture for use in relation to the method comprises a combination of cement, sand, water, polystyrene beads, wire fibers and a conditioning concrete additive.