Dynamic Mixed-Mode Fracture of Self-Compacting Steel-Fiber Reinforced Concrete

This work studies the influence of fiber content and loading rate on the mixed-mode dynamic fracture of self-compacting steel-fiber reinforced concrete. The specimens were prismatic beams for three-point bending tests, plain and reinforced with three fiber ratios (up to 0.6% in volume). They were sawn a notch cutting half of the depth at 1/4 of the span. Tests were performed at four loading rates: 2.2×10 -3 and 2.2 mm/s in a servo-hydraulic machine; 1.7×10 3 and 2.7×10 3 mm/s in a drop-weight device. The latter ones were recorded with a high-speed video camera. Results show that both the peak load and the inclination of the crack increase for faster rates. Besides, highly reinforced beams exhibit profuse crack branching for all the rates. As the fiber ratio increases, it is also observed that the main crack may either bifurcate or abruptly change its path when it gets closer to the loading point.