INVESTIGATION OF BEHAVIOUR OF RUBBERISED CONCRETE

Abstract

High impact resistance and energy-absorbing capability are beneficial properties of rubberised concrete. Rubberised concrete is highly effective in areas where more flexibility is required. Rubberised concrete has greater flexibility, impact resistance, and lower unit weight compared to conventional concrete. In this study, sulfuric acid is used in the surface treatment process of rubber particles to strengthen the bonding property of rubber particles and cement paste. Six waste tire rubber crumb contents (0, 10, 15, 20, 25, and 30%) and particle sizes of 0.6-2.36 mm were used to replace fine aggregate in concrete partially. Microstructural analyses (EDX, TGA, XRD) are conducted on rubber crumbs to examine rubber’s compatibility before using it in concrete. The fresh, hardened, microstructural properties (SEM and XRD), stress vs strain behaviour, pull off strength, impact-resistant, ultrasonic pulse velocity, and electrical resistivity of rubberised concrete are investigated. The durability properties (water absorption, acid attack resistance, and freeze-thaw attack resistance) are evaluated on the optimum mix of rubberised concrete. The mechanical properties of rubberised concrete reduce by increasing the rubber crumb in the mix; still, the mechanical properties of 90 days of water-cured concrete increase compared to 28 days of water-cured concrete. The results are not much troubling up to 15% replacement level of rubber crumb, and the rubberised concrete has a highly deformable capacity than conventional concrete. The SEM image analysed that the surface treatment technique improves the bonding properties of rubber particles and cement paste compared to untreated rubber particles. Impact resistance and energy absorption capacity of rubberised concrete are increased by 33.33% and 10% up to 15% replacement of rubber crumb. Two correlation equations have been established between the split tensile and compressive strength and flexural and compressive strength of concrete: fst=0.776 fc 0.39 and ffs=0.652 fc 0.5 , respectively. The results are not much troubling up to 15% replacement level of rubber crumb. The optimum dosage of rubber crumbs to replace fine aggregates is found to be 15% without significant losses in the properties of rubberised concrete. Structural analyses show that the specimens remain in the crystalline phase after being submerged in H2SO4 and HCl acid. When rubberised concrete is immersed in H2SO4 and HCl solution with equal concentrations and duration, Department of Civil Engineering, Delhi Technological University, Delhi. India. ABSTRACT viii specimens immersed in HCl solution have been found to have less surface erosion, less weight loss, and lower compressive strength loss. When the conventional concrete mix is immersed in H2SO4 and HCl solution, the losses in compressive strength are 74.56% and 30.34%, but in rubberised concrete, the losses are 60.01% and 24.22% only. No apparent microcracks and no spalling on the surfaces of the specimens are found up to 90 freeze-thaw cycles. Rubberised concrete’s ultrasonic velocity decreases slightly up to 90 freeze-thaw cycles, but it still has good concrete quality. Overall, the rubberised concrete is durable, with enough capacity to absorb the impact energy, and has a higher deformable capacity than conventional concrete.