寒区RAP配合比优化设计及路用性能研究

RAP热再生时的配合比、旧料掺量以及再生后混合料性能一直是近年来沥青路面再生与重建的重要话题。本文选择添加A-90新沥青作为RAP中老化沥青的再生方式,采用马歇尔设计方法对再生混合料AC-20的配合比进行优化设计;基于配合比设计结果,研究15%、20%、25%、30%四种RAP掺量对再生混合料路用性能的影响。研究结果表明:马歇尔法设计的再生沥青混合料体积指标以及性能指标均满足规范要求。RAP掺量不高于25%时,随RAP掺量的增加,再生沥青混合料的高温性能逐渐提升,低温抗裂性、水稳定性以及疲劳耐久性能逐渐下降。针对本文研究采用的RAP,结合呼伦贝尔的气候特征,推荐AC-20再生混合料RAP的最大掺量不宜超过25%。

Mix Optimization Design and Pavement Performance of RAP Mixture in Cold Region

The mix ratio,the amount of RAP,and the performance of recycled mixture have been the important topics of asphalt pavement recycling and reconstruction in recent years.Without considering the number of silos,the Marshall design method is used to optimize the mix ratio of AC-20 recycled mixture.Based on the mix design results,the effects of RAP content of 15%,20%,25%,and 30% on the pavement performance of recycled mixtures were studied. The results show that the volume indexes and performance indexes of recycled asphalt mixture designed by the Marshall method meet the requirements of specifications.When RAP content is not more than 25%,with the increase of RAP content,the high-temperature performance of recycled asphalt mixture gradually improves,and the low-temperature crack resistance,water stability,and fatigue durability gradually decrease.For the RAP used in this study,the maximum RAP content recommended for AC-20 is no more than 25% in the actual engineering application of Hulunbuir.