Asymmetrical Concrete Backerboard

Abstract

The present invention is a backerboard having a fiberglass mesh on one side, and a impervious reinforcement membrane on the other side. The backerboard incorporates a low density, high compressive strength concrete core having an upper principal surface and a lower principal surface. The upper principal surface of the core is covered by a fiberglass mesh reinforcement layer, itself covered and bonded to the core by a thin layer of Portland cement. The lower principal surface of the backerboard is covered with a high tensile strength, impervious reinforcement membrane.

What is claimed is: 
     
         1 . A prefabricated asymmetrical construction element comprising:
 a cementitious core including alkaline resistant fibers and having an upper principal face and a lower principal face;   an impervious non-cementitious reinforcement web disposed directly on the lower principal face of the core;   a cementitious bonding surface on the upper principal face of the construction element; and   a non-cementitious surface on the lower principal face of the construction element.   
     
     
         2 . The construction element of  claim 1 , the alkaline resistant fibers comprising chopped reinforcement fibers randomly dispersed in the core. 
     
     
         3 . The construction element of  claim 1 , the impervious non-cementitious reinforcement web comprising a reinforced polymer membrane. 
     
     
         4 . The construction element of  claim 1 , the impervious non-cementitious reinforcement web comprising water impervious paperboard. 
     
     
         5 . The construction element of  claim 1 , the impervious non-cementitious reinforcement web comprising spunbonded olefin. 
     
     
         6 . The construction element of  claim 1 , the impervious non-cementitious reinforcement web comprising an alkaline resistant dense polymer fiber mat. 
     
     
         7 . The construction element of  claim 1 , the core comprising Portland cement, alkaline resistant fibers, and one or more additives selected from the group consisting of expanded shale, expanded clay, sintered clay, pumice, slag, calcium carbonate, slate, diatomaceous earth, perlite, vermiculite, scoria, volcanic cinders, tuff, diatomite, sintered fly ash, industrial cinders, gypsum, foam beads and/or glass beads. 
     
     
         8 . A prefabricated asymmetrical construction element comprising:
 a cementitious core having an upper principal face and a lower principal face, the upper principal face having a single layer of pervious reinforcing mesh embedded in or adhered to the upper principal surface;   an upper cementitious coating disposed on the upper principal face of the core and the pervious reinforcing mesh;   an impervious non-cementitious reinforcement web disposed directly on the lower principal face of the core;   a cementitious bonding surface on the upper principal face of the construction element; and   a non-cementitious surface on the lower principal face of the construction element.   
     
     
         9 . A prefabricated asymmetrical construction element prepared by a process, wherein the prefabricated asymmetrical construction element comprises:
 a cementitious core including alkaline resistant fibers and having an upper principal face and a lower principal face;   an impervious non-cementitious reinforcement web disposed directly on the lower principal face of the core;   a cementitious bonding surface on the upper principal face of the construction element; and   a non-cementitious surface on the lower principal face of the construction element;   
       wherein the process comprises:
 running a continuous web of the impervious non-cementitious reinforcement web; and 
 depositing the core onto the impervious non-cementitious reinforcement web while the core is in a plastic state, the impervious reinforcement web remaining on the lower principal face of the core after the manufacture of the construction element. 
 
     
     
         10 . The prefabricated asymmetrical construction element prepared by the process of  claim 9 , the process further comprising placing a layer of pervious non-cementitious reinforcement material on the cementitious bonding surface. 
     
     
         11 . The prefabricated asymmetrical construction element prepared by the process of  claim 9 , the process further comprising running the continuous web of the impervious non-cementitious reinforcement web directly onto a conveyor belt. 
     
     
         12 . The prefabricated asymmetrical construction element prepared by the process of  claim 9 , the process further comprising curing the core. 
     
     
         13 . The prefabricated asymmetrical construction element prepared by the process of  claim 12 , the process further comprising permanently adhering the web of impervious non-cementitious reinforcement web directly to the cementitious core during curing of the core, the continuous web of impervious non-cementitious reinforcement web forming the non-cementitious surface on the lower principal face of the construction element as the construction element is removed from the conveyor belt 
     
     
         14 . The prefabricated asymmetrical construction element prepared by the process of  claim 9 , wherein the core is the first material or element placed on the web of impervious non-cementitious reinforcement web, and wherein the web of impervious non-cementitious reinforcement web is not a carrier sheet for the core, but is permanently attached to the core to form the lower principal face of the construction element. 
     
     
         15 . The prefabricated asymmetrical construction element prepared by the process of  claim 9 , the process further comprising cutting the construction element into panels.