Influence of Steel Fiber on Compressive Strength and Crack Pattern of Recycled Aggregate Concrete

The use of recycled aggregates rather than new aggregates is suggested by the depletion of natural resources and demolition trash. Compared to natural aggregate, recycled aggregate gives concrete less strength. Concrete can be strengthened by adding fiber, such as steel fibers, at a low volumetric proportion. This study aims to determine the concrete's compressive strength by adding steel fiber (30 mm in length) to volume fractions of 0.45%, 0.9%, 1.35%, and 1.80% of the concrete. Coarse aggregates specially recycled stone was obtained from demolished concrete structures and laboratory waste and used after proper treatment. Based on the mix design, a concrete strength of 30 MPa and a water to cement ratio of 0.46 were selected. This type of concrete was anticipated to be utilized for RCC beams. To make sure the designed concrete was workable, the slump test was conducted. The slump showed decreasing value when steel fiber was added accordingly. After seven and twenty-eight days, the concrete cubes' compressive strength was finally measured. With steel fiber utilized at the ideal proportion of 1.35% of the volume of concrete, the results demonstrated that the concrete achieved the required strength and slightly improved in compressive strength. In conclusion, steel fiber combined with recycled stone in the right proportion could be a sustainable substitute for RCC structures.