Dumping of Waste tire rubber is growing and posing serious problems for the environment. Therefore, research on recycling and treatment of waste tire rubber is becoming practised on a large scale. Treatment of waste tire rubber by thermo-mechanical devulcanization is found to enhance both mechanical properties and environmental conditions as the process does not include chemical substances. The present research highlights the findings of experimental analysis performed on the mechanical properties of normal and rubber concretes (RC) of grade M30 and M60 and the behaviour of 5-Dimensional (5D) steel fiber (fiber provided with additional hooks at both ends) incorporated in steel-fiber reinforced concretes (SFRC) beams (M30, M30RC, M60 and M60RC). The fibres are pre-coated with zinc phosphate to increase the bond mechanism and their frictional resistance thus resulting in higher load-carrying capacity. The compressive and split tensile strength of the SFRC specimen increases by 15.54 and 69.7% for pre-coated 5D steel fiber added in M60 concrete. The modulus of elasticity of RC reduces by up to 12.26% for grade M60 concrete. The ultimate strength of pre-coated 5D SFRC beams increases by up to 13.04 and 17.94% for M60 normal and RC respectively. The performance of devulcanized crumb rubbers in concretes was identified to be better in terms of flexural strength and modulus of elasticity when compared to normal crumb rubber concrete.

Keywords: 5-Dimensional steel fiber, Chemical treatment, Flexural strength, Rubber concrete, SFRC.