Compressive Strength Optimization of Concrete Using Varying Percentages of Steel Slag as SCM

Abstract

Compressive strength is the most important mechanical property of concrete, as it determines the load-carrying capacity and overall performance of structural elements such as columns, beams, slabs, and foundations. Conventional concrete mainly relies on natural aggregates to achieve the required compressive strength. However, due to increasing construction activities, the availability of natural aggregates is gradually decreasing, and their extraction is causing environmental problems. Steel-slag concrete is a type of concrete in which steel slag, an industrial by-product from the steel manufacturing process, is used as a partial or full replacement for natural aggregates. Steel slag has high hardness, angular particle shape, and rough surface texture, which can significantly influence the compressive behavior of concrete. These physical properties improve particle interlocking and enhance the bond between the cement paste and aggregate, leading to improved compressive strength. Several experimental studies have shown that concrete containing steel slag can achieve compressive strength comparable to or higher than conventional concrete, especially at later curing ages. The higher strength development is often attributed to the dense packing of slag particles and the presence of reactive compounds in steel slag that may contribute to secondary hydration reactions. As a result, steel-slag concrete tends to show improved strength gain over time. The compressive characteristics of steel-slag concrete are strongly affected by factors such as mix proportion, water-cement ratio, slag replacement level, curing age, and specimen size. At lower water-cement ratios, steel-slag concrete generally exhibits higher compressive strength due to reduced porosity. Proper mix design and proportioning are necessary to ensure strength, stability, and durability. Therefore, investigating the compressive characteristics of steel-slag concrete with different mixing ratios provides valuable information for developing sustainable and high-performance concrete while reducing dependence on natural aggregates and promoting industrial waste utilization