Experimental investigation of mechanical properties of crumbed rubber concrete containing natural zeolite

Global technology development and increased use of automobiles as major transportation means have resulted in growing waste rubbers. One of the effective ways of tire recycling is using these wastes as substances in construction materials, for example, concrete, to modify some of their mechanical properties. The main aim of this work is to improve mechanical properties of crumbed rubber concrete (CRC) by adding natural zeolite as partial replacement of cement. Furthermore, to improve cement-rubber bond, the surface treatment of the rubber particles was done with a 1 M aqueous solution of NaOH. Therefore, a total of 25 mix designs was built up. Crumbed rubber with the size of 1-6 mm and weight ratios of 5, 10 and 15% were partially replaced the coarse aggregates with a maximum size of 9 mm. To reduce the consumption of cement and improve concrete properties, 5,10 and 15 wt% zeolite were also added as partial replacement of cement to the concrete mixtures containing crumb rubber. Compressive strength, Brazilian tensile strength, flexural strength, specific weight and modulus of elasticity of the samples were examined. According to the results obtained, for all the percentages of added rubber, the mechanical properties decreased compared to ordinary mixed concrete. Only the performance of concrete containing 5% crumb rubber regarding flexural strength was improved in comparison with the other replacement percentages. However, the addition of zeolite caused improvements in all percentages added whereas the best performance were achieved in compressive strength and flexural strength related to samples containing 5% rubber, 15% zeolite, and 5% rubber, 10% zeolite, respectively. (C) 2019 Elsevier Ltd. All rights reserved.