Influence of steel fibers on the flexural performance of concrete incorporating recycled concrete aggregates and dune sand

The flexural performance of steel fiber-reinforced concrete made with recycled concrete aggregates (RCA) and desert dune sand was investigated. Natural aggregates were replaced by 30, 70, and 100% RCA. Steel fibers were incorporated into mixes in 1, 2, and 3% volume fractions. To evaluate the flexural behavior of plain and steel fiber-reinforced RCA concrete mixes, three- and four-point bending tests were conducted. Experimental results showed that RCA replacement had a predominant impact on compression behavior compared to steel fiber addition, while the latter was more influential on flexural performance. Higher pre-peak slope, flexural strength, deflection, toughness, and equivalent flexural ratio were noted when steel fibers were added to RCA-based concrete tested under four-point bending. Similar improvement in flexural performance was reported from load-crack mouth opening displacement curves of three-point bending tests. Accordingly, analytical regression models were developed to correlate the different properties obtained from these two flexural bending test results.