集料类型对砂粒式沥青混合料微观形貌的影响

Effect of Aggregate Type on Microstructure of Sand Asphalt Mixtures

为评价集料类型对细集料沥青混合料微观形貌的影响,采用三维景深显微镜和扫描电子显微镜深入研究了当集料选用石灰石、辉绿岩或钢渣时细集料沥青混合料的微观形貌。宏观上看,石灰石和辉绿岩砂粒式混合料表面较为光滑,钢渣砂粒式混合料表面较为粗糙,表面颜色差异较为明显。结果表明:石灰石砂粒式沥青混合料表面集料沙化,集料裸露,由黏附失效和黏聚失效共同主导;辉绿岩砂粒式沥青混合料表面褶皱,沥青和集料相间分布,黏聚失效占主导;钢渣砂粒式沥青混合料表面反光区域较多,为钢渣切割面,少量区域存在空隙,黏附失效占主导。三维景深结果与扫描电镜结果很好地吻合,因此,利用三维景深和扫描电子显微镜均可很好地评价砂粒式沥青混合料的微观形貌,特别是微区失效特性。

To evaluate the effect of the aggregate type on the microstructure of the fine aggregate asphalt mixture,this paper used the three-dimensional depth of field microscope and the scanning electron microscope to deeply study the microstructure of asphalt mixtures with fine aggregates of limestone,diabase,and steel slag.Macroscopically,the surface of the limestone and diabase sand mixture was smooth,while the surface of the steel slag sand mixture was rough and the color difference was obvious.The results showed that the aggregate on the surface of the limestone sand asphalt mixture was sanded and exposed,which was led by adhesion failure and cohesion failure.The surface of the diabase sand mixture was folded,and the asphalt and aggregate were interphase distributed,which was led by cohesion failure.There were lots of reflective areas that were cutting surfaces of the steel slag on the surface of the steel slag sand mixture,and a few areas had gaps,which was led by adhesion failure.The result of the three-dimensional depth of field microscope was in good agreement with that of the scanning electron microscope,therefore,both these two methods can well evaluate the microstructure of sand asphalt mixtures,especially the micro zone failure characteristics.