老化作用下沥青集料界面力学行为研究

为了探究老化对沥青混合料界面力学性能的影响,将不同温度老化处理的沥青制成的三明治试件进行剪切试验以模拟实际路面发生的破坏情况。通过分析应力-剪切位移的关系与界面破坏情况,研究在不同程度老化作用下沥青集料界面剪切破坏与沥青内部剪切破坏机理,并根据本试验的情况在已有的模型基础上完善出相对符合本试验的理论模型。试验结果表明:每组试验均产生单波峰与双波峰曲线,通过开尔文模型可知,之所以出现双波峰情况,是沥青弹性与粘性的共同作用导致的。随着沥青老化程度的加深,沥青流变性能降低,沥青集料界面的粘附性呈下降趋势,沥青的凝聚性呈先下降后上升趋势,老化加深到一定程度时,双波峰迅速减少,单波峰迅速增加,原因是随着老化程度的加深,沥青凝聚性反向增强,界面破坏只发生在沥青集料界面。

Research on mechanical behavior of asphalt-aggregate interface subjected to aging

In order to study the influence of aging on mechanical performance at the interface within asphalt-aggregate mixtures,shear experiments are carried out for sandwiched specimens composed of differently aged asphalt to simulate the practical interfacial failure on the road surface.By analyzing the stress-displacement relation and the interfacial failure,shear failure mechanism of asphalt-aggregate interface and asphalt itself is studied under different aging conditions.An improved theoretical model is proposed based on experimental results by consideration of previously-proposed models.Experimental results indicate that single-peak and double-peak curves occur inevitably for each test.According to the Kelvin model,double-peak curves can be attributed to the joint behavior of elasticity and viscosity of asphalt.As the asphalt is further aged,the rheology of asphalt is undermined,and the adhesion at the asphalt-aggregate interface will become weak while the cohesion of asphalt becomes weak initially and then becomes stronger with the aging degree.When the asphalt is aged to a certain degree,double-peak curves rapidly decrease and single-peak curves increase dramatically.The reason lies in that as the aging process goes further,the cohesion of asphalt is enhanced abruptly and the interfacial failure occurs only at the asphalt-aggregate interface under this condition.