Evaluating the Co-relationship between the mechanical properties of steel slag aggregate concrete reinforced with steel fiber

Abstract The growing need to conserve natural resources, effective management of industrial waste, and minimization of environmental pollution has encouraged the use of industrial waste as a sustainable construction material. Furthermore, in light of the rising scarcity of natural coarse aggregates (NCA) in many regions, it has become essential to identify viable alternatives. Hence, this study explored the effects of partially replacing NCA with steel slag aggregate (SSA) and incorporating varying volumes of steel fiber (SF) on the mechanical and microstructural properties of concrete. Initially, NCA was substituted with 50% SSA, and SF was subsequently added in volume fractions of 0.15%, 0.3%, 0.45%, 0.6%, 0.75%, 0.9%, 1.05%, 1.2%, and 1.35% to evaluate its combined impact on different concrete properties. The concrete mixes were evaluated through workability, fresh density, compressive strength (CS), split tensile strength (STS), flexural strength (FS), rebound hammer (RH), and field emission scanning electron microscopy (FESEM) tests. The results revealed that the mix with 50% SSA and 1.05% SF achieved optimal CS and RH values, while the mix containing 50% SSA and 1.2% SF demonstrated superior STS and FS. Compared to standard concrete (SC), the CS, RH, STS, and FS of the optimized mixes were enhanced by 33.19%, 41.37%, 36.47%, and 39.73%, respectively, showcasing the strength-enhancing potential of steel slag fiber-reinforced concrete (SSFRC). Furthermore, FESEM analysis indicated improved interfacial bonding in the SSFRC. Additionally, the experimental results were compared with existing empirical formulas, and regression models were developed to predict STS and FS from CS. Strong interrelationships were observed, with correlation coefficients of 0.988 and 0.963, respectively. This study highlights SSA as a sustainable alternative to NCA, contributing to resource conservation. The addition of SF further improves the overall properties of the concrete. These findings promote sustainable concrete by enhancing material efficiency and providing environmental benefits for future construction.