钢渣集料表面形貌对沥青吸收与黏附性能的影响分析

针对钢渣集料表面多孔、吸水率高、表面陈化裹附粉尘的问题，利用扫描电子显微镜(scanning electron microscope, SEM)和荧光显微镜分别分析钢渣集料表面形貌和钢渣集料与沥青黏结界面结构，通过计算机断层扫描(computed tomography, CT)定量分析钢渣集料表面开口孔隙与沥青渗透深度的关系，研究钢渣集料与沥青拌和浸渍后钢渣集料有效密度和沥青吸收率变化规律，并用滚瓶法试验来评价沥青与钢渣集料的黏附性能。试验结果表明钢渣集料表面存在独特的多孔结构和陈化产物层，而陈化产物层阻碍沥青与钢渣集料直接黏结，在界面处形成夹层结构，在动水摩擦作用下易导致沥青膜剥落。钢渣集料表面多孔结构对沥青只是部分吸收与填充，且与开口孔隙形状和大小存在较强依赖性，沥青渗透深度约为开口孔径的0.6倍。钢渣集料的吸水率和沥青吸收率具有很好的线性相关性，线性斜率约为0.39。与沥青拌和后，长期静置吸收沥青导致钢渣集料有效密度增加幅度小于0.5%。上述钢渣集料表面形貌特性可显著影响钢渣沥青混合料体积性能和抗水损害能力。

Effects of surface morphology of steel slag aggregates on asphalt absorption and adhesion performance

In order to investigate the problem of porous surface, high water absorption and aged surface coated with dust of steel slag aggregates, scanning electron microscope and fluorescence microscope were used to study the aggregate surface morphology and asphalt-aggregate interfacial bonding structure. X-ray computed tomography was used to conduct a quantitative analysis on the relation between the asphalt penetration depth and the open pore diameter on the surface of steel slag aggregate. After blended with asphalt binder and immersed in asphalt binder, the change of effective density and asphalt absorption rate over time was studied. The adhesion property between steel slag aggregate and asphalt binder was tested by using rolling bottle method. The test results show that the surface of steel slag aggregate exhibits a special porous structure and aging production layer. The latter prevents asphalt film from directly bonding with the surface of steel slag. This results in an interlayer within the adhesive interface. This interlayer can lead to the striping of asphalt film under the function of moving water and friction. The open pore of steel slag aggregate is partly absorbed and filled with asphalt binder. The degree of absorption and filling is strongly dependent on the shape and size of the open pores. The asphalt penetration depth is about 0.6 times of the open pore diameter. There is a good linear relation between the water absorption and asphalt absorption of steel slag aggregate and the linear slope is about 0.39. After blended with asphalt binder, the asphalt absorption in a long term will result in an increase of less than 5% on the effective density of steel slag aggregate. It is concluded that the aggregate surface characteristics of steel slag can have a significant effect on the volumetric properties and moisture damage resistance of asphalt mixtures.