Fracture behavior of plain and fiber-reinforced high strength concrete containing high strength steel fiber

With the increase in strength, concrete explodes spontaneously at failure creating a serious safety hazard. Researchers are actively looking for methods to arrest the cracks in concrete and design a higher strength concrete that fails in a more ductile fashion. Fiber-reinforced concrete has emerged as one of the solutions to this problem. This paper presents findings from the experimental investigation conducted to compare the fracture behavior of plain and fiber-reinforced high strength concrete of varying compressive strength. Six different concrete mixes were prepared with w/b ratios of 0.47, 0.36, and 0.20 resulting in average compressive strength of 36, 52, and 92 MPa. Each mix consists of two variations, first without fiber and second with 1% of steel fiber by volume. The mixes were tested for their strength and fracture Behavior using various standard codes and recommendations. From the Load-deflection and Load-CMOD (Crack Mouth Opening Displacement) curves obtained from the study, Fracture parameters like Fracture energy, Stress intensity factor, energy release rate, and Characteristic length is evaluated and compared for plain and Steel fiber reinforced concrete. It was found that adding steel fiber significantly improves the fracture properties of the concrete of different compressive strengths. By adding 1% of steel fiber in the high-strength concrete, the average fracture energy increased by 850%, 770%, and 450% respectively for the concrete with compressive strength of 36, 52, and 92 MPa. Other parameters also show a very significant improvement suggesting fiber reinforcement as a suitable choice to prevent brittle failure and increase the fracture performance of high strength concrete.