Patent Publication Number: US-2006000172-A1

Title: Lightweight concrete composite blocks

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation-in-part of application Ser. No. 10/374,886, filed Feb. 26, 2003, which was a continuation-in-part of U.S. Pat. No. 6,827,570 B2, issued Dec. 7, 2004.  
      This present application claims all available benefit, under 35 U.S.C. § 119(e), of U.S. provisional patent application Ser. No. 60/605,102, filed Aug. 27, 2004. By this reference, the full disclosure of U.S. provisional patent application Ser. No. 60/605,102 is incorporated herein as though now set forth in its entirety. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to lightweight concrete and, more particularly, but not by way of limitation, to unitary lightweight concrete composite blocks.  
      2. Description of the Related Art  
      Landscaping as well as gardening often requires the building of retaining structures in the form of walls, enclosed areas, and raised gardens or flower beds. Heretofore, landscape timbers have been the primary materials used in the construction of such walls, enclosed areas, and raised gardens or flower beds. While landscape timbers have functioned adequately, there are certain disadvantages in their use. Landscape timbers are chemically treated to make them resistant to rot and decay. Unfortunately, the chemicals employed to treat the landscape timbers, in particular arsenic and creosote, are toxic and thus harmful to the environment. Consequently, pollution occurs not only at production facilities but also at points of use since landscape timbers leach the treatment chemicals into the surrounding environment. Furthermore, landscape timbers ultimately rot and decay necessitating replacement in addition to more fully delivering the treatment chemicals into the environment. Accordingly, a block suitable for use in constructing walls, enclosed areas, and raised gardens or flower beds that is not chemically treated as well as resistant to rot and decay would be a significant improvement over current landscape timbers.  
     SUMMARY OF THE INVENTION  
      In accordance with the present invention, a lightweight concrete composite block includes polystyrene, cement, water, and glass mixed to formulate a lightweight concrete composite, which is then cured into the lightweight concrete composite block. The polystyrene may be recycled polystyrene ground into particles having a diameter of less than of an inch. The polystyrene comprises between 75% and 95% by total volume of the cement. The glass may be recycled glass ground into particles having a diameter of less than ¼ of an inch. The glass comprises between 40% and 45% by total weight of the cement. The water comprises between 40% and 50% by total weight of the cement. The lightweight concrete composite block may also include fly ash substituted for cement up to 20% by total weight of the cement. The lightweight concrete composite block may further include a calcium chloride accelerator mixed with the polystyrene, cement, water, and glass in an amount equal to 2% of total weight of the cement. The lightweight concrete composite block may still further include a hardening agent mixed with the polystyrene, cement, water, and glass in an amount equal to 2% of total weight of the cement.  
      In accordance with the present invention a method of manufacturing lightweight concrete composite blocks includes mixing polystyrene, cement, water, and glass to formulate a lightweight concrete composite and curing the lightweight concrete composite into lightweight concrete composite blocks. The polystyrene is ground into particles having a diameter of less than of an inch prior to mixing the polystyrene with the cement, water, and glass to formulate the lightweight concrete composite. The polystyrene comprises between 75% and 95% by total volume of the cement. The glass is ground into particles having a diameter of less than ¼ of an inch prior to mixing the glass with the polystyrene, cement, and water to formulate the lightweight concrete composite. The glass comprises between 40% and 45% by total weight of the cement. The water comprises between 40% and 50% by total weight of the cement. The lightweight concrete composite block may also include fly ash substituted for cement up to 20% by total weight of the cement. The lightweight concrete composite block may further include a calcium chloride accelerator mixed with the polystyrene, cement, water, and glass in an amount equal to 2% of total weight of the cement. The lightweight concrete composite block may still further include a hardening agent mixed with the polystyrene, cement, water, and glass in an amount equal to 2% of total weight of the cement.  
      In accordance with the present invention, a method of installing lightweight concrete composite blocks to build a retaining structure includes the use of lightweight concrete composite blocks comprising polystyrene, cement, water, and glass mixed to formulate a lightweight concrete composite, which is then cured into the lightweight concrete composite blocks. A first lightweight concrete composite block is cut to a desired length and placed at a desired location. A second lightweight concrete composite block is cut to a desired length, placed on the first lightweight concrete composite block, and then secured with the first lightweight concrete composite block. A third lightweight concrete composite block is cut to a desired length, placed adjacent the first lightweight concrete composite block, and secured with the first lightweight concrete composite block. A fourth lightweight concrete composite block is cut to a desired length, placed on the third lightweight concrete composite block and adjacent the second lightweight concrete composite block, and secured with the second and third lightweight concrete composite blocks.  
      It is therefore an object of the present invention to provide lightweight concrete composite blocks comprised of polystyrene, cement, water, and glass.  
      It is another object of the present invention to provide lightweight concrete composite blocks that do not introduce harmful chemicals into the environment.  
      It is a further object of the present invention to provide a method of manufacturing lightweight concrete composite blocks comprised of polystyrene, cement, water, and glass.  
      It is still a further object of the present invention to provide lightweight concrete composite blocks suitable for the building of retaining structures.  
      Still other objects, features, and advantages of the present invention will become evident to those of ordinary skill in the art in light of the following. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view illustrating a unitary lightweight concrete block according to a preferred embodiment.  
       FIG. 2  is a perspective view illustrating the use of unitary lightweight concrete blocks according to a preferred embodiment for building a retaining structure. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      As illustrated in  FIGS. 1 and 2 , a unitary lightweight concrete composite block  10  is rectangular with a horizontal axis greater than a vertical axis to facilitate stacking thereof for the building of retaining structures in the form of walls, enclosed areas, raised gardens, flower beds, and the like. While the preferred embodiment of the block  10  is rectangular to facilitate easier stacking thereof, those of ordinary skill in the art will recognize many alternative shapes, including but not limited to square, circular, triangular, polygonal, L-shaped, and the like.  
      The lightweight concrete composite utilized to form the blocks  10  includes polystyrene, which is typically recycled; cement, which is typically Portland; water; and glass, which is typically recycled, ground glass. The cement is stored in a hopper prior to delivery from the hopper into a mixer using suitable and well-known means such as an auger, conveyor belt, pneumatic blower, and the like. Likewise, the water is stored in a tank prior to delivery from the tank into the mixer using suitable and well-known means such as a pump, gravity feed, and the like. The polystyrene is loaded into a grinder, which is of a type well known to those of ordinary skill in the art, and ground into particles having a diameter of less than of an inch. After grinding, the polystyrene particles are stored in a hopper prior to delivery from the hopper into the mixer using suitable and well-known means such as an auger, conveyor belt, pneumatic blower, and the like. Likewise, the glass is loaded into a grinder, which is of a type well known to those of ordinary skill in the art, and ground into particles having a diameter of less than ¼ of an inch. After grinding, the glass particles are stored in a hopper prior to delivery from the hopper into the mixer using suitable and well-known means such as an auger, conveyor belt, and the like.  
      Lightweight concrete composite utilized in manufacturing blocks  10  is formulated by delivering the cement, water, polystyrene particles, and glass particles into the mixer. Cement is delivered into the mixer in a desired amount. Water is delivered into the mixer in an amount between 40% and 50% by total weight of the cement. Polystyrene particles are delivered into the mixer in an amount between 75% and 95% by total volume of the cement. Glass particles are delivered into the mixer in an amount between 40% and 45% by total weight of the cement. The mixer, which is of a type well known to those of ordinary skill in the art, combines the cement, water, polystyrene particles, and glass particles, thus forming a lightweight concrete composite.  
      After formulation of the lightweight concrete composite, the mixer delivers the lightweight concrete composite into forms via a screed assembly such as that disclosed in U.S. patent application Ser. No. 10/374,886, the disclosure of which is herein incorporated by reference. The forms are identical to the forms disclosed in U.S. patent application Ser. No. 10/374,886, except the cap is unnecessary and thus eliminated and the bottom assemblies are segmented to provide individual molds that produce multiple blocks  10 . The mixer delivers the lightweight concrete composite into the screed assembly, which, in turn, delivers the lightweight concrete composite into a form. Once the screed assembly completes delivery of the lightweight concrete composite into the form, a curing oven, such as that disclosed in U.S. patent application Ser. No. 10/374,886, cures the lightweight concrete composite within the form. A block removal station, such as that disclosed in U.S. patent application Ser. No. 10/374,886, removes the cured lightweight concrete composite blocks  10  from the form. A conveying system, such as that disclosed in U.S. patent application Ser. No. 10/374,886, routes forms in a continuous loop simultaneously through the screed assembly, curing oven, and block removal station, thereby creating a time efficient process.  
      The lightweight concrete composite utilized to form the blocks  10  includes at least polystyrene, cement, water and glass; however, the cost of formulating the lightweight concrete composite may be reduced through the substitution of fly ash for a portion of the cement. In particular, fly ash may be substituted for cement up to 20% by total weight of the cement. Consequently, fly ash may be added to any formulation up to 20% by total weight of the cement.  
      Furthermore, due to varying atmospheric conditions, in particular, temperature and humidity, it may be necessary to include in the lightweight concrete composite other additives that improve the performance characteristics thereof. One such additive is a calcium chloride accelerator that accelerates curing of the lightweight concrete composite. Another additive is a hardening agent that enhances hardening of the lightweight concrete composite. When used, the calcium chloride accelerator and the hardening agent are each added to the lightweight concrete composite in an amount equal to 2% of total weight of the cement.  
      To install the blocks  10  and thus build a retaining structure in the form of a wall, enclosed area, raised garden, flower bed, and the like, any uneven ground must first be leveled. If necessary a small trench may be dug to receive a bottom layer of the blocks  10 . Leveling ground or digging a trench is unnecessary if the blocks  10  will reside on a level surface such as a concrete patio. The blocks  10  are lightweight and thus easily carried. The blocks  10  are further easily cut with a saw and in particular a chain saw. Consequently, the blocks  10  may be cut if necessary to a desired size and laid end to end to form a first layer. The ends the blocks  10  further may be secured together using any suitable adhesive or fastener. Additional blocks  10  may be cut if necessary to the desired size and laid end to end on top of the first layer to form a second layer. Not only may the ends of the additional blocks  10  be secured together using any suitable adhesive or fastener, but also the additional blocks  10  forming the second layer may be secured to the blocks  10  forming the first layer using any suitable adhesive or fastener. Still further layers of blocks  10  may be stacked and secured as described above until the desired height for the retaining structure is reached. The ends of the blocks  10  may be cut at any angle so that retaining structures with different shapes may be constructed. Illustratively, three, four, five, and more sided retaining structures may be built depending upon the angle of the cut along an end of a block  10 . The blocks  10  are accordingly extremely advantageous for building retaining structures in the form of a walls, enclosed areas, raised gardens, flower beds, and the like because they are lightweight, easily cut and stacked, and more importantly do not introduce harmful chemicals into the environment.  
      Although the present invention has been described in terms of the foregoing embodiment, such description has been for exemplary purposes only and, as will be apparent to those of ordinary skill in the art, many alternatives, equivalents, and variations of varying degrees will fall within the scope of the present invention. That scope, accordingly, is not to be limited in any respect by the foregoing description; rather, it is defined only by the claims that follow.