Utilization of Higher Percentages of RAP for Improved Mixture Performance by Adopting the Process of Fractionation

The study investigates the significance of fractionation as a process for the use of higher percentage of Reclaimed Asphalt Pavement (RAP) material in the design of bituminous mixtures. The fractionation is a process in which the RAP material is separated into two or more fractions to ensure consistency in the RAP gradation. In this study, the sieve analysis was carried out on the milled RAP material collected from five different locations to find the variation in the gradation. As the variation in the gradation was observed to be similar in nature for the milled RAP material obtained from all the five different locations, the detailed study was carried out on the RAP material from one particular location. The results showed that a 3-level fractionation had a significantly low variation in the RAP gradation even with the addition of 60% RAP material. A detailed study was carried out on the bituminous mixtures with three fractionation levels (un-fractionation, 2-level fractionation, and 3-level fractionation) and with three RAP percentages (40, 50 and 60). The ANOVA analysis showed that when compared to a 2-level and an un-fractionated RAP, a 3-level fractionated RAP substantially minimizes the variability in air voids, voids in mineral aggregate, Marshall stability, indirect tensile strength ratio, and Cantabro loss for the RAP added bituminous mixtures.