Physico-chemical properties of cement-waste rubber composites

The influence of waste rubber as well as irradiation process on the physico-chemical and thermal properties of cement-waste rubber composites was investigated. The mortar specimens were made from ordinary Portland cement OPC with partial replacements of OPC by rubber used wastes with 5, 10 and 20% substitution by weight. The mixtures were moulded into I inch cubic moulds. The specimens were first cured for 24 hrs., at 100% relative humidity and then cured under tap water for further six days followed by irradiation at different doses of gamma-irradiation namely 5, 10, 20, 30 and 50 kGy, respectively. Compressive strength, total porosity, water absorption and bulk density were measured. The samples were subjected to thermogravimetric analysis (TGA) to examine their thermal stability. The results show that, the values of compressive strength and bulk density of the cement-waste rubber composite increase with the increase of gamma-irradiation dose up to 10 kGy and then gradually decrease at higher irradiation doses. As the waste rubber percent increases the values of compressive strength and bulk density decrease, while the water absorption and total porosity percentage behave in an opposite direction. TGA data show that the cement-waste rubber composite containing 10% waste rubber has a higher thermal stability as compared to the composite containing 20% waste rubber.