The use of steel fibers to enhance the performance of concrete made with recycled aggregate

This research investigates the effect of replacing natural coarse aggregates with recycled concrete aggregates (RCA) on the performance of normal-strength (30 MPa) concrete. To promote 100% replacement, steel fibers were incorporated at 0-2%, by volume (vf). Locally-abundant dune sand served as sustainable fine aggregates. Physical, rheological, and mechanical properties were evaluated through experimental testing, including slump, density, compressive strength, and flexural strength. Results of plain concrete showed that an increase in RCA replacement led to a decrease in density and slump. The addition of steel fibers increased the density but decreased the slump. Compared to the control sample, the compressive and flexural strengths decreased by 18 and 51% with 100% RCA replacement. The incorporation of 2% steel fibers could restore the former by 90% and nearly doubled the latter. Findings provide evidence on the feasibility of producing steel fiber-reinforced normal-strength concrete with 100% RCA that is suitable for structural applications.