What are the roles of adding fiber into cement mortar?

Since cement mortar is a brittle material, with the tensile strength much less than its compressive strength, the impact resistance and crack resistance are poor. There exist a lot of dry shrinkage cracks and temperature cracks in the cement products. These cracks continue to change and develop over time, which eventually can result in cracking of cement products, lead to reduction in the anti-permeability performance of structures and affect the durability.

The most direct and effective way to overcome this defect of cement products is to add fiber. Adding an appropriate amount of fiber into cement mortar can increase the tensile strength, enhance toughness, and improve resistance to cracking. The addition of fiber into cement mortar can prevent the extension of original defect cracks in the mortar matrix, effectively prevent and delay the emergence of new cracks; improve the rigidity of mortar matrix, increase toughness, reduce brittleness, improve the deformation capacity and impact resistance of mortar matrix; improve the density of mortar matrix and prevent the invasion of external moisture, thereby improving its water resistance and permeability resistance; improve the frost resistance and fatigue resistance of mortar matrix, and enhance its durability.