Variability Associated with the Resilient Modulus of Reclaimed Asphalt Pavements

Research on reclaimed asphalt pavement (RAP) material has been on its high all over the world since last three decades. Sustainability, cost effectiveness and eco-friendliness of RAP make it a potential secondary alternative in pavement applications. Often, to meet the strength and stiffness requirements, RAP is blended with virgin aggregates (VA) at various proportions. The resilient modulus (Mr) of base material plays a major role in deciding the pavement thickness. A considerable amount of variability in the Mr values of RAP is observed from laboratory and field studies all over the world. In view of the increased usage of RAP, there is a definite need to understand the statistical variability associated with the Mr of RAP. In this paper, the variability associated with Mr is quantified statistically. Based on the compilation of Mr values from several published studies, the average values of mean, standard deviation, coefficient of variation (COV), and the best fit probability density functions for Mr are computed. The appropriate distributions for RAP and VA mixes are discussed. The outcome of the study will be useful to quantify the performance of the flexible pavements using reliability based design optimization (RBDO) framework which is based on the probability theory.