Optimization of fiber volume fraction to enhance reinforcing efficiency in hybrid fiber reinforced strain hardening cementitious composite

The steel fibers were generally used to improve the compressive strength of hybrid fiber reinforced strain hardening cementitious composite (SHCC) due to its higher strength and modulus. It is crucial to rationally design the volume fraction of fibers to maximize the role of different fibers in hybrid fiber reinforced SHCC. In this study, a design philosophy was proposed to guide the synthesis of hybrid fibers reinforced SHCC with saturated multiple cracking. The practical design criteria were determined by the joint use of cracking saturation index and pseudo strain hardening (PSH) performance indices. Finally, the design criteria were used to determine the volume fraction of steel fiber in hybrid fiber reinforced SHCC. Based on the proposed method, the optimum steel fiber volume fraction of 0.68% in hybrid fiber reinforced SHCC with 1.5% volume fraction of PE fibers was obtained for a designated matrix.