Correlating the Strength Parameters of Rubber Modified Asphalt Concrete

Abstract

Building verified models can help in predicting performance characteristics of asphalt concrete and saving time and money. An attempt has been made in the present investigation to prepare asphalt concrete mixtures for wearing course. Crumb rubber was implemented to prepare modified asphalt binder, which was obtained from Nasiriyah, Erbil, and Dourah oil refineries. Asphalt concrete specimens of control and rubber modified binder have been prepared and tested for Marshall stability, stiffness, and indirect tensile strength. Test results of such strength parameters were analyzed and correlated. It was revealed that when (8 and 16) % of crumb rubber was implemented in the asphalt concrete mixtures, higher intercept, and slope of the (tensile strength-stiffness) relationship could be detected among various binder origin and higher intercept of the (tensile strength-stability) relationship values could be detected while the slope is generally increased. It was noted that mixtures of Dourah asphalt binder exhibit the highest tensile strength as represented by the intercept of the (tensile strength-stiffness) relationship of 90.8 kPa as compared with mixture of Nasiriyah and Erbil asphalt binders with (88.16 and 77.1) kPa intercept values. However, Mixtures with Erbil asphalt binder exhibits the lowest intercept of the (tensile strength-stability) relationship of 255.6 kPa as compared to mixtures of  Nasiriyah and Dourah asphalt binders with intercept values of (327.1 and 407.2) kPa respectively. It was concluded that the mathematical models obtained fits into the experimental observation with high accuracy. Hence, the models are practical to be used to predict the changes in tensile strength properties of asphalt concrete with the variation in stiffness and stability.