Minimizing the crumb rubber effects on the flexural behaviour of the layered RC beams cast using rubberized concrete with or without recycled tire steel fibers

Abstract

The huge amount of crumb rubber (CR) produced from cars' tires and others causes environmental problems while using natural concrete components reduces their amounts in nature. So, using recycled wastes to replace the concrete components became essential. Herein, the functionally graded material (FGM) approach was implemented to reduce the bad effects of the recycled materials on the beam behavior. Nine reinforced concrete (RC) beams were tested experimentally (under four-point bending) and simulated numerically using the ABAQUS program. The first beam was a control beam (CB) made from plain concrete (PC), while the cross-section of the rest beams was divided into three equal horizontal layers along the beam span. The middle layer was cast from rubberized concrete (RuC) with CR% (30%, 50%, and 80%) as a partial sand replacement, while the top layer was made from PC. Consequently, the bottom layer was made from different patterns of RuC and recycled tire steel fiber (RSF) concrete. The numerical model was extended to involve the presence of RuC in the top layer and opening in the middle layer on the beam behavior. The test results demonstrated trivial effects on the loads' capacities compared to CB, maximum reduction = 3.8% for beams cast with RuC in their middle layers. Moreover, the beams cast with RuC containing up to 20% and 80% CR in their bottom and middle layers could attain about 94.3––99% of the CB load. These findings encouraged using CR in concrete to reduce its harmful environmental effects and save the natural sand by about 13.3–16.6%.