Hardened properties of concrete with different proportion of crumb rubber and fly ash

The utilisation of waste materials in concrete is one of the sustainable construction approaches introduced in the industry that can indirectly reduce the environmental issues arisen from the disposal problem of the wastes. The aim of this study is to investigate the hardened properties of rubberised pozzolanic concrete (RuPC) with different proportion of crumb rubber and fly ash as partial fine aggregate and ordinary Portland cement (OPC) replacement, respectively. The crumb rubber content replacing fine aggregate is in the range of 0% to 20% while fly ash replacing cement ranges from 0% to 30%. Testing of RuPC with different percentage of crumb rubber and fly ash were performed at the age of 28 days for density, compressive, splitting tensile and flexural strength, and were compared with properties of control specimens. Results showed that the density of RuPC decrease with increase in crumb rubber and fly ash content. The overall strength of RuPC decrease as crumb rubber content increase in which 5% crumb rubber show the least reduction in strength. Replacing 10% cement with fly ash shows improvement in the strength of RuPC when compared to specimens without fly ash, however still lower than strength of control specimen. The optimum crumb rubber replacement is 5% while fly ash is 10% to avoid significant reduction in strength.