Experimental Study of Hot Recycled Asphalt Mixtures with High Percentages of Reclaimed Asphalt Pavement and Different Recycling Agents

Abstract

Hot recycled mixture has been widely used as binder course on highways in the Jiangsu Province, China. The objectives of this study were to evaluate recycled mixture's performance with different Reclaimed Asphalt Pavement (RAP) contents and recycling agents (RA). At first, optimum RA contents were determined according to asphalt blending charts based on penetration index. Secondly, the performance of recycled mixtures and control virgin asphalt mixture was evaluated based on retained stability, Tensile Strength Ratio (TSR), dynamic stability (DS), failure strain, and fatigue life. Thirdly, statistical significance on the basis of analysis of variance was evaluated as a function of RAP contents and RA type. The results indicated that adding RA could improve moisture stability, low temperature cracking resistance, while decreasing high temperature stability and strength performance of recycled mixture. Recycled asphalt mixture Sup-20 with RA has similar performance compared to virgin asphalt mixture Sup-20. The former has better moisture stability and high temperature stability than that of the latter, with a slight reduction in low temperature cracking and fatigue resistance. With a fixed RA-2, TSR, and failure strain of recycled mixes decreases, and DS first slightly decreases and then increases, while fatigue life first increases and then decreases with increasing RAP contents. The results indicated that the interface status and blending level between recycled asphalt and aggregate is variable due to the mixing process and material compositions, which results in the varied performance results of recycled mixes due to the different test temperatures, loading modes, and testing periods, etc. Furthermore, the results of analysis of variance are consistent with the experimental test results.