Lightweight Polymer Concrete Composition

Abstract

A lightweight foamed polymer concrete admixture for use in fabricating building components, the polymer concrete comprising a mixture of a polyol, an isocyanate, an aggregate, and water, wherein once mixed, the mixture releases carbon dioxide gas creating a foamed mixture that may be shaped to form a building component such as, but not limited to, lap siding, shake siding, trim boards, stone and stucco sheeting.

We claim: 
     
         1 . A method for fabricating a building product from a curable polymer concrete composition comprising;
 (a) admixing: (1) a polyol, (2) an isocyanate, (3) an aggregate; and (4) water, wherein the water and isocyanate react to provide crosslinking and evolve carbon dioxide gas resulting in a foamed admixture;   (b) placing the admixture in a mold defining the contours of the building product wherein the evolving carbon dioxide gas is entrained in the admixture causing the volume of the admixture to increase;   (c) curing the admixture in the mold; and   (d) removing from the mold the defined building product with a specific gravity in the range of about 0.7 to 1.5.   
     
     
         2 . The method of  claim 1 , wherein the polyol is either a vegetable oil based polyol or a petroleum based polyol. 
     
     
         3 . The method of  claim 1 , wherein the mold is either a closed mold or a continuous belt mold. 
     
     
         4 . The method of  claim 1 , wherein when placed in the mold the volume of the admixture increases in the range of about 50 to 300 percent. 
     
     
         5 . The method of  claim 1 , wherein the polyol comprises in the range of 5 to 15 percent of the total mass of the admixture. 
     
     
         6 . The method of  claim 1 , wherein the isocyanate is in the range of 5 to 15 percent of the total mass of the admixture. 
     
     
         7 . The method of  claim 1 , wherein a surfactant is admixed with the polyol, iscocyanate, aggregate and water to form the admixture. 
     
     
         8 . The method of  claim 1 , wherein the aggregate is a mineral composition with an average particle size distribution range from about 10 to 1,000 microns. 
     
     
         9 . The method of  claim 8 , wherein the mineral composition is an inorganic mineral. 
     
     
         10 . The method of  claim 1 , wherein the aggregate comprises in the range of from about 50 to 95 percent of the mass of the admixture. 
     
     
         11 . The method of  claim 10 , wherein the aggregate preferably comprises 80 percent of the mass of the admixture. 
     
     
         12 . The method of  claim 1 , wherein the water comprises at least 0.1 percent of the mass of the admixture. 
     
     
         13 . The method of  claim 1 , wherein the components shaped from the admixture are selected from the group consisting of roof shakes, siding shakes, bricks, paving stones, stucco sheeting, lap siding, fascia, trim, decking products and flooring. 
     
     
         14 . The method of  claim 1 , wherein the tensile modulus of the cured admixture is in the range of from about 2810-4650 Mpa. 
     
     
         15 . The method of  claim 1 , wherein the flexural strength of the cured admixture is in the range of from about 380-560 Mpa. 
     
     
         16 . The method of  claim 1 , wherein the density of the cured admixture is in the range of about 0.7 to 1.5 g/cm 3 . 
     
     
         17 . The method of  claim 1 , wherein the coefficient of thermal expansion of the concrete polymer mixture when fully cured is in the range of from about 10.2 μm/m° C. to 40.6 μm/m° C. 
     
     
         18 . The method of  claim 1 , wherein the isocyante is preferably the aromatic isocyanate diphenylmethane diisocyanate. 
     
     
         19 . The method of  claim 1 , wherein a catalyst is used to accelerate the curing time of the admixture. 
     
     
         20 . A system for producing a polymer concrete for use in fabricating building products, the system comprising:
 (a) a polyol, an isocyanate, an aggregate; and water, that are mixed together wherein the water and isocyanate react to provide crosslinking and evolve carbon dioxide gas resulting in a foamed admixture;   (b) a set volume of the foamed admixture is placed into a closed mold to expand because of the evolving carbon dioxide gas, the admixture completely filling the void within the mold;   (c) the admixture cured within the mold at a variable temperature in the range of 60 to 120° C. and for approximately 2 hours; and   (d) the building product is removed from the closed mold and cured again for a period of approximately 16 hours at 70° C., wherein the density of the cured building product is in the range of from 0.7 to 1.5 g/cm 3 .   
     
     
         21 . The system of  claim 20 , wherein the polymer composition may be decorated prior to removal from the mold. 
     
     
         22 . The system of  claim 21 , wherein the polymer composition may be painted to reveal decorative weathering. 
     
     
         23 . The system of  claim 20 , wherein a mesh is integrated within the admixture at the time of placement of the admixture into the mold. 
     
     
         24 . A polymer concrete composition useful for fabricating lightweight building products, the polymer concrete composition comprising;
 (a) aggregate in an amount in the range from about 50 to 90% by weight of the polymer concrete composition;   (b) polyol in an amount in the range from about 10 to 20% by weight of the polymer concrete composition;   (c) isocyanate in an amount in the range from about 5 to 15% by weight of the polymer concrete composition; and   (d) water in an amount of at least 0.1% by weight of the polymer concrete composition, wherein the sum of the components (a) through (d) add up to 100 weight % and after the product is cured in a continuous belt mold the polymer concrete exhibits a density of from about 0.7 to 1.5 g/cm 3  and a flexural strength of from about 0.6 to 1.0 Mpa.   
     
     
         25 . The polymer concrete composition of  claim 24 , wherein fibers are added to the admixture in the range of about 1 to 5%. 
     
     
         26 . The polymer concrete composition of  claim 25 , wherein chopped glass fibers preferably about one-quarter inch in length are added to the admixture. 
     
     
         27 . The polymer concrete composition of  claim 25 , wherein milled glass fibers preferably about one-sixteenth inch in length are added to the admixture. 
     
     
         28 . The polymer concrete composition of  claim 25 , wherein cellulose fibers are added to the admixture. 
     
     
         29 . The polymer concrete composition of  claim 25 , wherein cotton fibers preferably about 4 mm in length are added to the admixture. 
     
     
         30 . The polymer concrete composition of  claim 24 , wherein the cured building product is covered with a cap comprised of polyvinyl chloride in a thickness ranging from about 0.003 to 0.005 inches. 
     
     
         31 . The polymer concrete composition of  claim 24 , wherein the cured building product is covered with a cap comprised of acrylonitrile styrene acrylate in a thickness ranging from about 0.003 to 0.005 inches. 
     
     
         32 . The polymer concrete composition of  claim 24 , wherein the composition is cured in a mold for 2 hours at 100° C. and then demolded and cured for at least 2 hours at a temperature between 60 and 120 ° C.