Date of Award


Document Type


First Advisor

Abu-Lebdeh, Dr. Taher


Motivated by the tremendous trend toward green environment and to reduce the effect of scrap tires on the environment, this research is an attempt to find a practical and environmentally sound solution of the problem of scrap tires. A few literatures are available about the effect of crumb rubber on thermal conductivity (k-value) of mortar. Furthermore, almost there is no studies have considered the effect of crumb rubber on the thermal properties of gypsum materials. For this purpose, an experimental program was established to investigate the amount and size of crumb rubber (rubber obtained from recycling scrap tires) on the thermal properties of mortar and gypsum. Four levels of sand replaced with crumb rubber 10%, 20%, 30%, and 40% and three sizes of crumb rubber (#30, #10_20 and combination of both sizes) considered to make twelve rubberized mortar and eight rubberized gypsum specimens. The specimens tested for thermal conductivity using an apparatus constructed for this purpose. Water absorption and unit weight of rubberized mortar were tested. It was found that the size and the amount of crumb rubber had an effect on thermal properties of the specimens investigated. k-value decreased when amount of rubber increased. Thermal conductivity of rubberized mortar was13 – 28% lower than the ordinary mortar and rubberized gypsum was18 – 38% lower than the ordinary gypsum. The water absorption of mortar mixtures contained up to 20% of crumb rubber inclusion was lower than that of plain mortar. In regard of rubber particle size, courser rubber particles gave higher reduction in k-value if compared to finer size. The materials investigated in this research can be used as coating material to improve thermal insulation property of exterior walls.Two equations to predict k-value of mortar and gypsum consist of crumb rubber were proposed. Finally, finite element approach to convert amount of rubber used in each mixture to a layer of rubber was used to develop equations to estimate the k-value of mortar and gypsum containing crumb rubber.