Wood strand cement boards with a prctically closed surface and production process

Abstract

A mineral bonded Wood Strand Cement (usually Portland cement or Magnesite or Gypsum) Board which is produced from a mixture of wood strands or a similar fibre material, water, a suitable binder like cement, and possibly additives, which mixture is cured under pressure to form a board with a practically entirely closed surface. For the boards according to the invention, wood strands are being used that are broader and thinner than used until presently in acoustic Wood Wool Cement Boards. Moreover, the invention relates to a method of orienting wood strands and a production process for the production of such Wood Strand Cement Boards.

What is claimed is: 
     
         1 . A wood strand cement board, manufactured from a mixture consisting essentially of:
 wood strands not of woody grasses, a major portion of all said wood strands having a length of at least 250 mm;   a cement binder; and   water;   which mixture is cured to form a board with a practically entirely closed surface;   wherein said wood strands have a width of at least 2 mm, a width of maximally 12 mm, and a thickness of at least 0.15 mm and maximally 1 mm and wherein the weight ratio of water to wood strands is maximally 1.20:1; and   wherein said wood strands are not embedded in a matrix of cement; and   wherein edges of the strands are pointed at angles of less than 120°.   
     
     
         2 . A board as described in  claim 1  wherein at least 50% of the wood strands are oriented more longitudinally than transversely to the length of the board. 
     
     
         3 . A board as described in  claim 1 , wherein said wood strands have width of at least 3 mm. 
     
     
         4 . A board as described in  claim 3 , wherein said wood strands have a width of at least 6 mm. 
     
     
         5 . A board as described in  claim 1 , wherein said wood strands have a width of maximally 10 mm. 
     
     
         6 . A board as described in  claim 1 , wherein said wood strands have a thickness of maximally 0.5 mm. 
     
     
         7 . A board as described in  claim 1 , wherein said board comprises a board with corrugated or trapezium shaped profiles. 
     
     
         8 . A board as described in  claim 1 , wherein said board comprises at one of its surfaces a closed cover layer comprising a mixture for totally closing said surface of the board. 
     
     
         9 . A board as described in  claim 1 , wherein said weight ratio of water to wood strands is maximally 1.10:1. 
     
     
         10 . Beams, strips, lath or planks sawn from relatively thick boards as described in  claim 1 . 
     
     
         11 . An I beam assembled from strips, lath or planks obtained according to  claim 10 . 
     
     
         12 . A profile assembled from strips, lath or planks, obtained according to  claim 10 .