再生集料沥青混凝土高温形变损伤机理研究

Research on Damage Mechanism of Recycled Aggregate Asphalt Concrete during High Temperature Deformation

为了探究再生集料沥青混凝土高温形变的损伤机理,采用不同再生集料用量制备沥青混凝土,通过单轴贯入试验测试再生集料对沥青混凝土抗剪切性能的影响规律,并基于X-ray CT获取高温形变破坏前后其内部细观结构的演化特征。研究结果表明:再生集料的附着水泥砂浆具有多孔隙结构特征,沥青混凝土中水泥砂浆与沥青砂浆界面呈高孔隙率的弱联结状态;粗集料的级配加权球形度为0.812~0.825、加权棱角性指数为1.023~1.125时,再生集料沥青混凝土的高温抗剪切强度最佳;再生集料用量增大会导致沥青混凝土细观结构损伤加剧,水泥砂浆内部、水泥砂浆与沥青砂浆界面的破坏是沥青混凝土高温形变损伤主要诱因;再生集料替代沥青混凝土中天然骨料的用量应控制不超过50%。研究论证了再生集料形貌和内部界面损伤对沥青混凝土高温性能的影响规律,对再生集料沥青混凝土路面的应用具有一定的理论和实践意义。

In to order explore the damage mechanism of recycled aggregate asphalt concrete(RAAC) during high temperature deformation, asphalt concrete specimens with different contents of recycled aggregate(RA) is prepared. Then the effect of RA on RAAC’s resistance to high temperature deformation is studied through uniaxial penetration test. Finally, the internal mesostructure of RAAC before and after high temperature deformation are scanned by CT. The results show that attached cement mortar is a porous material, and its interfacial adhesion to asphalt mortar is weak. With a weighted sphericity within 0.812~0.825 and weighted angularity within 1.023~1.125, RAAC is featured with the best high temperature stability. Increasing the content of RA can lead to more interface failure during RAAC’s high temperature deformation, and the failures of cement mortar inside and cement mortar to asphalt mortar interface are the main resources for high temperature deformation damage. When RA is used as a substitute for natural aggregate in asphalt concrete, the amount of RA should not exceed 50%. The study verifies that the recycled aggregate morphology and internal interface failure have influences on RAAC’s resistance to high temperature deformation, the the findings have certain theoretical and practical significance for the application of recycled aggregate asphalt concrete pavement.