Patent ID: 8133352

Claim:
A method of making a fiber cement composite building material incorporating cellulose fibers, the method comprising: washing the cellulose fibers at an elevated temperature washing process between about 65 degrees Centigrade to about 120 degrees Centigrade to reduce COD content of the cellulose fibers to less than 4.5 kg/ton, wherein the COD content of the cellulose fibers alone is measurable from a filtrate after a portion of the cellulose fibers alone are dispersed in a solution in the absence of cement and measured prior to being combined to form the fiber cement composite building material; and incorporating the reduced COD cellulose fibers into a cementitious mixture for making the fiber cement composite building material, wherein the reduced COD cellulose fibers comprise about 2% to 20% by weight of the fiber cement composite building material, and wherein the reduced COD cellulose fibers increase strength reinforcement to the fiber cement composite building material when formed by increasing the modulus of rupture (MOR) of the fiber cement composite building material by more than about 10% as-compared with a fiber cement composite building material made with a same formulation containing cellulose fibers with COD content greater than 5 kg/ton of oven dried pulp measurable from a filtrate.