Influence of Waste Rubber Powder on the Mechanical and Abrasion Resistance Properties of Concrete

In the river environments of Xinjiang characterized by high sediment content and high flow velocities, hydraulic concrete is highly susceptible to damage from the impact and abrasion of bed load. Consequently, this imposes more stringent requirements on its mechanical properties and abrasion resistance. The incorporation of crumb rubber, a recyclable material, into concrete presents a dual benefit: it enables resource recycling while simultaneously offering a novel pathway for the development of concrete technology. This study takes rubber powder concrete as the research object. With the same water-to-binder ratio, rubber powder was incorporated at three volume fractions: 0%, 5%, and 10% of the cementitious material. The drop weight impact test and underwater steel ball method are adopted to evaluate its impact resistance and anti-scouring-abrasion performance, respectively. By testing the compressive strength, impact toughness, wear rate, anti-scouring-abrasion strength and three-dimensional morphological characteristics, the influence of rubber powder content on the mechanical properties and anti-scouring-abrasion performance of concrete is systematically analyzed. The research results show that the addition of rubber powder reduces the compressive strength of concrete, but significantly improves its impact resistance and anti-scouring-abrasion performance. Among all test groups, the concrete with 10% rubber powder content has the most significant decrease in compressive strength, with a decrease of about 37% compared with the 5% content group, while the 5% content group has a decrease of about 27% compared with the control group. However, its impact toughness at 3d, 7d and 15d is increased by about 84.7%, 88.4% and 84.4%, respectively, compared with the control group, showing the largest improvement range. At the same time, the wear rate of this group is reduced by about 42.5%, and the anti-scouring-abrasion strength is increased by about 61%. Combined with the three-dimensional morphology analysis, it can be seen that the specimens in this group exhibit the optimal anti-scouring-abrasion performance. In terms of microstructure, the porosity of rubber powder concrete increases, the generation of C-S-H gel decreases and its continuity is damaged, leading to a significant decrease in compressive strength. The reduction in the generation of delayed ettringite enhances the toughness and anti-scouring-abrasion performance. In general, the increase in rubber powder content will lead to a decrease in the compressive strength of concrete, but within a certain range, it can significantly improve its impact resistance and anti-scouring-abrasion performance. Crumb rubber effectively enhances the impact and abrasion resistance of hydraulic concrete, demonstrating strong application potential in high-flow, sediment-laden river environments.