Demarcation Study on Reclaimed Asphalt Pavement Contents in Recycled Hot Mix Asphalt Mixtures for Wearing Course in Asphalt Pavements

Abstract

The present study evaluated reclaimed asphalt (RAP) containing hot mix asphalt (HMA) mixtures performance, to assess the effect of 5% RAP alteration on the marginal change in performance between 20%, 25%, and 30%. Then, the results from assessment were used to classify the RAP contents in HMA mixtures as low, moderate, and high by comparing the performance of the mixtures. The HMA specimen’s preparation followed the Marshall mix design procedure with a 12.5 mm nominal maximum aggregate size (NMAS). Rutting and stripping resistance were selected as the primary performance. The wheel tracking (WTT) and indirect tension strength (IDT) tests were done to assess rutting and stripping performance, respectively. The WTT results indicated that a mixture with 30% RAP performed well in rutting resistance, followed by 25% and 20% RAP mixtures. The results of the tensile strength ratio (TSR) from the IDT showed that mixtures with 0% RAP and 20% RAP were susceptible to stripping. On the other hand, mixture with the 25% RAP had good stripping resistance. From the test results, it was observed that RAP contents up to 20 % had similar performance as 0% RAP mixture. Mixtures containing 25% RAP and 30% RAP found better on rutting and stripping resistance. Based on the experiment results, the 5% variation in RAP content affects the performance of the mixtures significantly. The present study concluded that RAP content could be tiered as follows; up to 20 % is low content, above 20% to 30% as moderate, and above 30% is high content.