USE OF CRUMB RUBBER TO IMPROVE THERMAL EFFICIENCY OF CEMENT-BASED MATERIALS

Motivated by the tremendous trend toward green environment and to reduce the effect of scrap tires on the environment and human health, this research is an attempt to find a practical and environmentally sound solution of the problem of scrap tires by developing a light weight with low thermal conductivity composite construction materials using waste tires. A few literatures may be found about the effect of crumb rubber on thermal conductivity of mortar. Thus, in this research project, an experimental program was established to investigate the effect of the amount and size of crumb rubber (rubber obtained from recycling scrap tires) on the thermal properties of mortar. Four levels of crumb rubber addition: 10, 20, 30 and 40% and three sizes of crumb rubber (#30, #10_20 and a combination of both sizes) were considered to make twelve different mixtures of the rubberized mortar. Specially designed and constructed heat transfer measurement device was used to measure thermal conductivity of the specimens. Results were used to determine the optimal amount of crumb rubber that gives the least thermal conductivity, which directly related to the improvement in thermal resistance of concrete mixtures. It was found that the size and the amount of crumb rubber had an effect on thermal properties of the specimens investigated. The thermal conductivity of rubberized mortar was decreased by 28% when crumb rubber #10_20 was used. It was also found that #10_20 crumb rubber had more effect on the thermal conductivity reduction than #30 crumb rubbers. An empirical equation is proposed to predict thermal conductivity of rubberized mortar.