Effect of steel fibers on the performance of concrete made with recycled concrete aggregates and dune sand

Abstract

This paper aims to develop and evaluate the performance of steel fiber-reinforced concrete made with recycled concrete aggregates (RCA) and desert dune sand. Different fresh and hardened properties of RCA concrete mixtures with and without steel fibers were evaluated and compared with those of a mixture made with natural coarse aggregates (NA). Test parameters included the RCA replacement percentage and steel fibers (SF) volume fraction (v f ). Test results showed that the substitution of 30% of NA with RCA in plain concrete mixes did not reduce the design cylinder compressive strength (f′ c ), whereas the use of higher percentages of RCA replacement compromised the fresh and hardened properties of the concrete. The addition of SF significantly reduced the adverse effects caused by the inclusions of RCA in the mixes. RCA-based concrete mixtures having 70 and 100% RCA replacements could be produced with f′ c values comparable to that of a NA-based concrete, when minimum v f values of 1, and 2% were added, respectively. The RCA replacement increased the water absorption and sorptivity but decreased the ultrasonic pulse velocity, bulk resistivity, and abrasion resistance. The addition of SF improved the hardened properties of RCA-based concrete mixes to an extent of exceeding some of those of the NA-based counterpart, as in the case of abrasion resistance. Analytical regression models were introduced to correlate different concrete properties to the 28-day cylinder compressive strength.