Methods of making smooth reinforced cementitious boards

Abstract

Methods and a reinforcement fabric are disclosed for making a reinforced smooth cementitious board having a cement skin adjacent to an outer face, by depositing a reinforcement fabric and a layer of hydraulic cementitious material, one on the other, wherein the reinforcement fabric comprises an open mesh united with a thin, porous nonwoven web.

What is claimed is: 
     
         1 . A reinforcement fabric for reinforcing a smooth cementitious board, wherein the reinforcement fabric comprises:
 an open mesh united with a porous nonwoven web, wherein the open mesh is configured to be penetrated by a layer of hydraulic cementitious material, and wherein the porous nonwoven web comprises polypropylene fibers configured to promote penetration of the porous nonwoven web by at least a portion of the layer of hydraulic cementitious material to form a cement skin adjacent to an outer face of the smooth cementitious board.   
     
     
         2 . The reinforcement fabric of  claim 1 , wherein the open mesh comprises glass fibers coated with an alkali-resistant material. 
     
     
         3 . The reinforcement fabric of  claim 2 , wherein the glass fibers are dip-coated with the alkali-resistant material. 
     
     
         4 . The reinforcement fabric of  claim 2 , wherein the open mesh comprises glass fibers co-extruded with the alkali-resistant material. 
     
     
         5 . The reinforcement fabric of  claim 2 , wherein the open mesh comprises glass fibers sheathed with the alkali-resistant material and wherein the sheathed fibers are fused together at intersections within the open mesh. 
     
     
         6 . The reinforcement fabric of  claim 5 , wherein the glass fibers are wrapped with fibers of the alkali-resistant material, and wherein the fibers of the alkali-resistant material are fused to provide the glass fibers sheathed with the alkali-resistant material. 
     
     
         7 . The reinforcement fabric of  claim 2 , wherein the alkali-resistant material comprises an olefin, a polyolefin and olefin copolymer, a polypropylene, a polyethylene, a copolymer of polybutylene and propylene, an ethylene propylene rubber (EPR), a thermoplastic polyolefin rubber (TBR), a polyvinyl chloride compound, a polyvinylidene chloride, an ethylene-propylene dienemonomer (EPDM), a copolymer of styrene and butadiene (SBR), or any combination thereof. 
     
     
         8 . The reinforcement fabric of  claim 7 , wherein the alkali-resistant material comprises a polyvinyl chloride plastisol. 
     
     
         9 . The reinforcement fabric of  claim 1 , wherein the open mesh comprises a grid with a strand count between about 2 and about 15 strands per inch. 
     
     
         10 . The reinforcement fabric of  claim 2 , wherein the glass fibers comprise a linear density between about 33 and about 300 tex. 
     
     
         11 . The reinforcement fabric of  claim 1 , wherein the porous nonwoven web comprises a spunbonded web, a chemical-bonded web, or a carded web. 
     
     
         12 . The reinforcement fabric of  claim 1 , wherein the porous nonwoven web consists essentially of polypropylene fibers. 
     
     
         13 . The reinforcement fabric of  claim 1 , wherein the open mesh is united to the porous nonwoven web by stitching means, adhesive means, heated means, pressure means, or any combination thereof. 
     
     
         14 . A method of making the reinforcement fabric of  claim 1 , the method comprising:
 coating an open mesh of glass fibers with an alkali-resistant material;   contacting the open mesh with a porous nonwoven web of polypropylene fibers; and   uniting the open mesh with the porous nonwoven web to form the reinforcement fabric.   
     
     
         15 . The method of  claim 14 , wherein uniting comprises stitching, adhesive fixing, heat fusing, or any combination thereof. 
     
     
         16 . The method of  claim 14 , wherein coating comprises dip-coating. 
     
     
         17 . The method of  claim 14 , wherein contacting the open mesh with the porous nonwoven web and uniting the open mesh with the porous nonwoven web occur during the coating of the open mesh with the alkali-resistant material. 
     
     
         18 . The method of  claim 14 , wherein the alkali-resistant material comprises a polyvinyl chloride (PVC) plastisol. 
     
     
         19 . The method of  claim 14 , wherein the porous nonwoven web consists essentially of polypropylene fibers.