再生沥青混合料复合骨架与细观力学性能的离散元分析

Discrete Element Analysis of Composite Skeleton and FineMechanical Properties of Recycled Asphalt Mixtures

基于3D扫描获得粗集料轮廓特征指标,建立具有新旧集料、新旧沥青明显特征的再生沥青混合料复合材料离散元模型,研究再生沥青混合料复合骨架特性及微裂缝发展特征.提出考虑抗车辙和抗裂性能均衡的RAP掺量确定方法.结果表明:RAP掺量对再生沥青混合料复合骨架接触数量影响不大,主要影响沥青胶浆及其接触处的界面力学性能.复合骨架粗集料相互作用过程中,接触点处存在压应力、拉应力、拉压混合应力.荷载作用范围内集料相互作用主要为压应力,荷载作用两侧区域同时存在压应力和拉应力.对于RAP掺量对裂缝发展的影响,包括RAP料接触界面区域产生较多剪切裂缝,而沥青胶浆内剪切裂缝相对较少;RAP-RAP、RAP-新集料、新集料-新集料接触界面,以及沥青胶浆内存在大量拉伸裂缝.加载过程中剪切裂缝主要位于荷载作用区域范围,数量增加相对较慢,而拉伸裂缝遍布于沥青混合料试件,数量增加较快,剪切裂缝数量为拉伸裂缝的50%~80%.

Based on the characteristic index of coarse aggregate profile obtained by 3D scanning,the discrete element model of recycled asphalt mixture composite material with obvious characteristics of new and old aggregate and new and old asphalt was established,and the composite skeleton characteristics and micro-crack development characteristics of recycled asphalt mixture were studied.A method for determining the content of RAP considering the balance of anti-rutting and anti-cracking performance was proposed.The results show that the content of RAP has little effect on the contact number of composite skeleton of recycled asphalt mixture,but mainly affects the mechanical properties of asphalt mortar and its interface.During the interaction between coarse aggregate and composite skeleton,there are compressive stress,tensile stress and mixed stress.The interaction between aggregates in the range of load is mainly compressive stress,and both compressive stress and tensile stress exist in the areas on both sides of load.The influence of RAP content on crack development includes that there are more shear cracks in the contact interface area of RAP material,while there are relatively few shear cracks in asphalt mortar.There are a lot of tensile cracks in rap-rap,rap-new aggregate,new aggregate-new aggregate contact interface and asphalt mortar.During the loading process,the shear cracks are mainly located in the range of load action area,and the number increases relatively slowly,while the tensile cracks are all over the asphalt mixture specimens,and the number increases rapidly,and the number of shear cracks is 50-80%of the tensile cracks.