Evaluating the fresh and mechanical properties of steel slag aggregate concrete reinforced with steel fiber

In this study, steel slag (SS) and steel fiber (SF) were used to make environment-friendly high-strength concrete. Natural coarse aggregate (NCA) was initially substituted partially with SS at various substitution levels, i.e., 25 %, 50 %, 75 %, and 100 %, respectively, for getting the optimum substitution levels of SS in concrete. Afterward, SF, having an aspect ratio of 60, was considered with volume fractions of 0.15 %, 0.3 %,0.45 %, 0.6 %, 0.75 %, 0.90 %, 1.05 %, and 1.2 % in concrete. The water-to-binder ratio was taken as 0.35 for all the concrete mixes. For the fresh property, slump and compaction factor of concrete were determined. Similarly, for the mechanical property compressive strength (CS), split-tensile strength (STS), and flexural strength (FS) have been tested after the curing age of 28 and 56 days. Additionally ultrasonic pulse velocity (UPV) test was conducted to measure the quality of concrete. X-ray diffraction (XRD) was also performed to analyze crystalline phases and identify mineralogical composition within the concrete matrix. All the tests were compared with the standard concrete made with NCA. It has been found that the addition of steel slag aggregate (SSA) and SF enhances the mechanical properties of concrete, whereas it reduces workability. Substituting 50 % of SSA for NCA alongside 1.05 % of SF results in the highest CS, while employing 1.2 % SF achieves maximum STS, FS, and UPV.