Experimental Investigation of the Effect of Fiber on Mechanical Properties and the Age of High-Performance Fiber Reinforced Cement Composites

High-Performance Fiber Reinforced Cement Composites (HPFRCC), are mortars exhibit strain hardening behavior in the tensile test also have features such as flexibility, Durability, and high energy absorption capacity. In this paper, the effect of the fiber on the characteristics of the HPFRCC mechanical properties, the Fracture pattern and the energy absorption capacity have been investigated. Since there is no specific standard test available for HPFRCC, first, 18 mixing designs with different material proportions were made, the mixing that was the most economical and has the most appropriate mechanical properties has been selected. Finally, the selected mixing was evaluated with 60 specimens in three states of non-fibers, one and two percent fibers at different ages. The results indicate that with increasing age of specimens in all three conditions, the tensile and compressive strength increased, also the pattern fracture of the specimens has been improved by adding the fibers has moved from the deep cracks and the fragmentation of the specimens to the surface cracks .Also energy absorption capacity increased by 1 and 2 percent fiber, 24 and 52 percent, respectively. Then the relations for determining the compressive strength at different ages and the calculation of tensile strength with compressive strength for plain concrete presented in the standard were also evaluated for HPFRCCs.