钢渣沥青混合料疲劳性能及改善机理

采用钢渣替代部分粗集料,制备了4种钢渣掺量的沥青混合料,并对其进行不同应变水平下的四点弯曲疲劳试验,分析钢渣掺量和应变水平对混合料疲劳性能的影响,以揭示疲劳性能改善机理.结果表明:随着钢渣掺量的增加,沥青混合料疲劳寿命呈先增加后降低的趋势,峰值出现在钢渣掺量为30%(质量分数)时;钢渣沥青混合料初始劲度模量和疲劳寿命均随着应变水平的增大而降低;疲劳损伤演化过程可分为失稳、平衡、失效3个发展阶段,疲劳失效劲度模量衰减比S_r/S_(50)小于50%,并随着应变水平的增大而逐渐减小;疲劳裂纹扩展主要发生在矿料-沥青界面处,且受应变水平影响较大;钢渣的化学性质和表面构造在改善界面相结构方面起到了交互黏附和嵌入锚固作用,用钢渣作为粗集料可显著提升沥青混合料的疲劳性能.

Fatigue Properties and Improvement Mechanism of Steel Slag Asphalt Mixture

Steel slag asphalt mixtures with four kinds of steel slag contents were prepared. The four point bending fatigue test was carried out to analyze the influence of steel slag content and strain level on the fatigue properties and to reveal the improvement mechanism of fatigue performance. Results show that the fatigue life of asphalt mixture first increases and then decreases with the increase of steel slag content, and the peak appears at steel slag content of 30%(by mass). The initial stiffness modulus and fatigue life of steel slag asphalt mixture significantly reduce with the increase of strain level, the fatigue damage evolution process can be divided into three stages: instability, balance and failure. The fatigue failure modulus attenuation ratio Sr/S50 is less than 50%, and gradually decreases with the increase of strain level. The fatigue crack growth mainly occurs at the mineral asphalt interface and is affected by the strain level. The chemical properties and surface structure of steel slag provide the interactive adhesion and embedded anchor effect for the interface phase structure. Steel slag can significantly improve the fatigue properties of asphalt mixture when used as coarse aggregate.