Synergy in Flexure of High-Performance Fiber-Reinforced Concrete with Hybrid Steel Fibers

Abstract

In this paper, the synergistic flexural behaviors of high-performance fiber-reinforced concrete (HPFRC) under static and cyclic loading were experimentally investigated. The HPFRCs were composed of an identical mortar matrix but different embedded fiber types and contents as follows: HPFRC0 (no fiber, 0.0% by volume), HPFRC1 (macro steel fiber, 1.5% by volume), HPFRC2 (micro steel fiber, 1.5% by volume), and HPFRC3 (hybrid fiber, 1.0% by volume macro steel fiber blended with 0.5% by volume micro steel fiber). All flexural specimens with the dimensions of 40×40×160 mm were tested under static and cyclic loading using a three-point bending fixture. The HPFRCs with embedded fibers demonstrated the clear enhancements in static flexural resistances of up to 3.54 times higher in flexural strength and 2.16 times higher in deflection capacity in comparison with the plain HPFRC. Under cyclic loading, the fatigue stress ratio, defined as the ratio of the fatigue stress amplitude to the static flexural strength, was changed to perform the fatigue behaviors of the HPFRCs. The endurance limits of the HPFRCs were observed more than 10,000 cycles at the fatigue stress ratio of 0.15, and exceeded 1,000 cycles at the fatigue stress ratio of 0.5. The order of the HPFRC series in terms of static flexural strength, static deflection capacity and fatigue life at the stress amplitudes more than 5 MPa were as follows: HPFRC3 > HPFRC2 > HPFRC1 > HPFRC0. A synergy behavior of the HPFRCs was observed for static flexural strength, static deflection capacity, and fatigue life with the stress amplitude more than 5 MPa. In addition, two models of the fatigue responses of the HPFRCs were built to predict the fatigue life of the HPFRCs according to applied cyclic load.