Evaluation of rejuvenator’s effectiveness on the reclaimed asphalt pavement incorporated stone matrix asphalt mixtures

The need for incorporation of Reclaimed Asphalt Pavement (RAP) in the Stone Matrix Asphalt (SMA) mixtures is becoming a priority in the pavement industries. The RAP offers several benefits such as the reduction in usage of bitumen, and natural aggregates, and reduction in the landfills, emission into the environment and cost. SMA is known for its success in improving rutting resistance, durability and cracking resistance and to utilize the benefits of both RAP and SMA, it seems a logical purpose to incorporate RAP in the SMA mixtures. However, RAP contains an aged binder, which increases the stiffness of the mixtures and a rejuvenator is added to improve the rheology of the aged binder. In this study, Waste Vegetable Oil (WVO) is used as a rejuvenator in the RAP incorporated SMA mixture. In order to determine the maximum RAP content and optimum WVO dosage, four RAP contents (10, 20, 30, and 40% by weight of the aggregate) and four WVO dosages (0, 3, 6, and 9% by weight of bitumen content) are used to prepare the SMA mixtures. The laboratory tests were conducted to evaluate drain down, volumetric properties, Marshall characteristics, stripping behaviour, Retained Marshall Stability (RMS), and Tensile Strength Ratio (TSR) and they are compared statistically to each other and to the control mixture. The results indicate that RAP incorporated SMA mixtures have a substantial positive effect on the volumetric properties and it enhanced the Marshall Stability (MS), stripping resistance and RMS, however, reduced the TSR value. To the contrary, the addition of the WVO improved the TSR value to a great extent and increased the RAP content. The statistical analysis, Analysis of Variance (ANOVA) results, showed that the RAP content and WVO dosage have a significance on the properties of the SMA, and the main effect plot results concluded that it is possible to incorporate 40% of RAP content with 6% WVO in the SMA mixtures.