Fiber reinforced cementitious substrate

A process for preparing a glass fiber-reinforced cement sheet which comprises dewatering a cement-containing slurry on a wire to form a wet film and winding said wet film on a making roll;

• the improvement which comprises utilizing in the process an aqueous, cement-containing slurry having a solid content of from 2-30 wt% and wherein the solid component of said slurry comprises 1 to 10 wt% glass fibers, and at least one member selected from the group consisting of 1 to 10 wt% asbestos and 0.03 to 5 wt% of a specific fiber wherein said specific fiber is selected from the group consisting of cotton, flax, hemp, wools and silk with the remainder cement material.