重复荷载作用下乳化沥青冷再生混合料集料运动特性研究

Study on Aggregate Movement Characteristics of Cold Recycled Mixture with Asphalt Emulsion under Repeated Loading

为探究乳化沥青冷再生混合料在重复荷载作用下内部集料的运动规律,基于重复荷载试验,利用二维数字图像处理技术对不同碾压时段乳化沥青冷再生混合料内部的集料接触点、长轴状态、分维数以及嵌挤规律等集料运动指标进行研究。结果表明:随碾压时间的增长,集料接触点数量增多;集料长轴方向的走势趋于一致,长轴倾角、分维数逐渐减小;集料与胶浆面积比逐渐增大,嵌挤状态逐渐密实。通过对混合料内部集料运动的变化规律进行分析,可以将乳化沥青冷再生混合料在重复荷载的作用下主要分成3个阶段:前期压密阶段、碾压密实阶段、碾压破坏阶段。重复荷载作用下混合料产生的车辙轮迹主要是由于内部集料受荷载作用发生了各种运动,进而使得集料的接触点数量、长轴的被压倒程度和胶浆比增大以及分维数降低,通过分析以上指标能够掌握在重复荷载作用下乳化沥青冷再生混合料集料的运动特性。

In order to investigate the movement of internal aggregates of cold recycled mixture with asphalt emulsion under repeated loading,two-dimensional digital image processing techniques were used to study the aggregate movement indicators based on repeated loading test with aggregate contact points,long axis state,fractal dimension and the in-line extrusion variation index of the aggregates in the cold recycled mixture with asphalt emulsion at different rolling periods.The results show that as the rolling time increases,the number of contact points of the aggregate increases;the direction of the long axis of the aggregate tends to be consistent,the long axis inclination angle and the number of fractional dimensions gradually decrease;The area ratio of aggregate gradually increases,the in-line extrusion variation in the mixture is gradually dense.By analyzing the internal aggregates movement of the mixture variation pattern,the cold recycled mixture with asphalt emulsion in the action of repeated loads can be divided into three main stages:initial compaction stage of the aggregate,relative compaction stage of the aggregate,and destruction stage of the aggregate.Rutted wheel tracks under repeated loading are mainly due to various movements of the internal aggregate which in turn results in the number of contact points increase,the degree of overturning of the long axis and the increase in the area ratio of aggregate,as well as a decrease in the number of fractional dimensions.The analysis of the above indicators can grasp the aggregate movement characteristics of cold recycled mixture with asphalt emulsion.