Evaluation of performance-based mix design for asphalt mixtures containing Reclaimed Asphalt Pavement (RAP)

Abstract

In this research, the possibility of producing asphalt mixtures containing Reclaimed Asphalt Pavement (RAP) that perform well from both fatigue and rutting points of view was studied. For this, seven asphalt mixtures with varying RAP percentage and total binder content were produced. All other variables, including the gradation and binder type, were kept constant. To better control for the production variables, the mixtures were produced in the laboratory. Fatigue and rutting properties of the mixtures were evaluated using the Simplified Viscoelastic Continuum Damage (S-VECD) model and Triaxial Stress Sweep (TSS) test, respectively. Next, FlexPAVETM software was utilized to predict the long-term fatigue and rutting behavior of the study mixtures. Fatigue and rutting predictions were then assessed simultaneously to determine the suggested performance-based optimum binder contents. The results showed that increasing the RAP content and/or reducing the binder content deteriorates the fatigue resistance while improves the rutting performance. Also, the suggested performance-based optimum binder content slightly increased as the RAP percentage increased, but it was still below the optimum binder content suggested by the Superpave volumetric mix design for the RAP percentages up to 40 percent. The study indicated that it is possible to produce an economical well-performing asphalt mixture by balancing fatigue and rutting performances.