2.3 Natural fiber cement flat sheets In accordance with ASTM c1185 and ASTM c1186 standards the experiments for determining the mechanical properties of the different cellulose fiber ement flat sheers were conducted on 30 x 15 x 0.5 cm spedmen to obtain the products that are suitable to use. Both types of cellulose fibers were tested using ratios of 5% and 10% by weight of Portland cement to determine their flexural strengths