基于RAP粗集料温拌再生沥青混合料的抗裂性能

Cracking Resistance of Warm-Mix Recycled Asphalt Mixtures Based on RAP Coarse Aggregate

摘要:

采用约束试件温度应力试验和半圆弯曲试验，结合数字图像相关技术和机器学习方法，研究了废旧沥青混合料（RAP）粗集料替代新粗集料对温拌再生沥青混合料低温抗裂性能的影响，并分析了不同影响因素下热拌和温拌再生沥青混合料低温抗裂性能的差异。结果表明：温拌工艺未对再生沥青混合料低温抗裂性能产生显著影响；低温抗裂性能评价指标冻断温度与断裂能对于评价再生沥青混合料低温抗裂性能有较好的一致性；荷载-位移曲线和水平应变-时间曲线将再生沥青混合料的开裂过程分为4个阶段，且低温下温拌再生沥青混合料的抗荷能力和变形能力均优于热拌再生沥青混合料；低温抗裂性能影响因素的重要程度排序为RAP粗集料掺量>新沥青掺量>盐冻融循环>水冻融循环>长期老化。

Abstract:

The effects of replacing virgin coarse aggregate with recycled asphalt pavement（RAP） coarse aggregate on the low-temperature cracking resistance of warm-mix recycled asphalt mixtures were investigated by thermal stress restrained specimen test and semi-circular bend test combined with digital image correlation technology and machine learning methods. The differences of low-temperature cracking resistance between hot-mix and warm-mix recycled asphalt mixture under different influencing factors were analyzed. The results indicate that the warm-mix technology has no significant effect on the low-temperature cracking resistance of the recycled asphalt mixtures. The fracture temperature and fracture energy have good consistency for evaluating the low-temperature cracking resistance. The load-displacement curves and time-dependent strain curves divide the cracking process of recycled mixtures into four stages， and the load-bearing capacity and deformation resistance of warm-mix recycled mixtures are superior to those of hot-mix recycled asphalt mixtures at low temperatures. The order of importance of the influencing factors on low-temperature cracking resistance is as follows： RAP coarse aggregate content>virgin asphalt content>salt freeze-thaw cycle>water freeze-thaw cycle>long-term aging.