The Impact of Waste Steel Fibers and Crumbed Rubber on Eco-Friendly High-Strength Concrete

This research investigated the mechanical properties, impact resistance, and behavior under elevated temperatures of Fiber Rubberized High-Strength Concrete (FRHSC), which incorporates Waste Steel Fiber (WSF) and Crumbed Rubber (CR) obtained from waste tires. The study involved five different concrete mixtures to explore the impact of WSF and CR. WSF was consistently mixed in a ratio of 0.3% by volume of the concrete. CR was used to partially replace the fine aggregate in proportions of 10%, 20%, 30%, and 40% by volume. The study examined various characteristics of both the fresh and hardened FRHSC, including slump, unit weight, compressive, tensile, and flexural strengths, as well as its impact resistance. The effects of elevated temperatures at ambient, 200 °C, 400 °C, and 600 °C for a period of 2 hours were also analyzed, focusing on the failure shape, and residual compressive strength. Findings indicated that as the quantity of rubber in the concrete samples increased, there was a noted gradual decline in their mechanical properties. Concurrently, this increase in rubber content contributed to an enhancement in the ductility of the samples. The energy absorption by the rubberized specimens was found to be consistent, regardless of the variation in rubber content due to the presence of WSF. The residual compressive strengths of FRHSC subjected to elevated temperatures improved with the addition of CR. The presence of CR led to an increase in the concrete's porosity, and exposure to high temperatures resulted in more cracks due to CR evaporation and the replacement of air voids, causing a notable reduction in compressive strengths. Keywords Fiber reinforced Concrete; Crumb rubber; waste steel fiber; waste tires, Rubberized concrete; Impact energy; Mechanical properties; Elevated temperature.