Evaluation of mechanical characteristics of high strength steel fiber reinforced concrete with various concrete strengths

Abstract

The performance of concrete is robust in compression but lacks tensile strength, making it brittle. Steel fibres are added to enhance concrete properties. These fibres play a crucial role in construction by improving structural performance, preventing cracks, and increasing ductility. The study investigated high-strength steel fibre-reinforced concrete (HSSFRC) with varying concrete strengths. Three high-strength concrete grades (70 MPa, 80 MPa, and 90 MPa) and different water-cement ratios (WCR) (0.25, 0.30, and 0.35) were studied. Hooked-ended 50mm steel fibres were added at content levels of 0.25%, 0.50%, 0.75%, and 1.00%. As steel fibre content increased from 0.25% to 0.75%, the compressive strength (CS) improved by 3.37%, 7.29%, and 10.54%. At the same time, the split tensile strength (STS) increased by 20.86%, 24.07%, and 26.74%. Similarly, the flexural strength (FS) increased by 19.87%, 23.12%, and 25.82% for a WCR of 0.25 in 70 MPa grade of concrete. However, adding 1.0% steel fibre led to decreased mechanical properties. The optimal steel fibre content across all concrete mixes was 0.75%. Mechanical properties weakened with higher WCR (0.25, 0.30, and 0.35). Additionally, regression analysis explored the relationships between CS, STS, and FS in the concrete mixes. The comparison between the test results and the regression analysis was carried out alongside the previous empirical formulas. Remarkably, the empirical formulas exhibited strong alignment with the experimental findings.