Effect of Recycled Aggregate Concrete and Steel Fibers on the Strength of Self-Compacting Concrete

The accumulation of waste materials in landfills without treatment threatens public health and the environment. The quantity of solid waste continually increases, causing environmental pollution. One of these wastes that should receive scientific treatment is concrete waste. The use of concrete waste as fine or coarse aggregate in self-compacting concrete (SCC) is one of the useful solutions to this problem. This study aims to reuse concrete waste as coarse aggregate in the production of SCC and find out the influence of different steel fiber contents on the strength of SCC. The steel fibers (SF) were used to reinforce SCC in three different volumes (0, 0.5, and 1 % of concrete volume), and the recycled coarse aggregate (RCA) was used to replace natural coarse aggregate (NCA) in five replacement levels of 0, 25, 50, 75, and 100%. The compressive and tensile strengths of the SCC specimens in the hardened state were determined. The results of the experimental study refer to the steel fiber having a positive effect on the enhancement of mechanical properties, particularly the tensile strength of SCC. The addition of 50% recycled aggregates in the concrete mix contributed to increasing the compressive strength by about 20%. Therefore, it can be said that the dual use of recycled aggregates with steel fibers produced concrete with high specifications compared to ordinary concrete. Another positive effect lies in the disposal of concrete waste, which contributes to an economic return in addition to reducing the effect on the environment