基于间接拉伸试验的沥青-集料界面黏结性研究

Study on Interfacial Adhesion of Asphalt Aggregate Based on Indirect Tensile Test

为研究沥青-集料界面黏结性能,选取70号基质沥青及SBS改性沥青混合料在不同温度、老化、水分条件下进行间接拉伸试验,通过分析其峰值力、断裂能、开裂容忍指数(CT)来表征沥青与集料间的黏结性,揭示各影响因素对沥青-集料的影响特征。结果表明,沥青混合料的峰值力随温度升高而降低,但断裂能及CT指数随温度升高而增大,温度在本质上改变了沥青的黏弹性质,从而使得沥青与集料的界面黏结性能发生显著改变。随着老化程度的加剧,沥青混合料峰值力增大而断裂能、CT指数降低,在长期老化条件下,70号基质沥青与SBS改性沥青的峰值力分别增长31.1%,15.4%,而断裂能分别减少27.6%,19.1%,老化作用提升了沥青混合料的黏结强度,但抗裂性及延展性遭到削弱。长期高温浸水处理后,沥青混合料的峰值力、断裂能、CT指数均发生显著下降,在高温浸水4 d后,70号基质沥青和SBS改性沥青混合料的峰值力分别下降48.2%,33.1%,CT指数分别降低67.7%,32.5%,水分侵入沥青-集料界面造成了沥青膜的剥离,严重影响沥青-集料界面的黏结性。

In order to study the interface bonding properties of asphalt and aggregate,70#matrix asphalt and SBS modified asphalt mixture were selected to perform indirect tensile tests under different temperature,aging and moisture conditions.The bonding properties between asphalt and aggregate were characterized by analyzing their peak force,fracture energy and cracking tolerance index(CT),and the influence characteristics of various influencing factors on asphalt and aggregate were revealed.The results show that the peak force of asphalt mixture decreases with the increase of temperature,but the fracture energy and CT index increase with the increase of temperature.Temperature essentially changes the viscoelastic properties of asphalt,and thus the interface bonding properties of asphalt and aggregate change significantly.With the increasing degree of aging,the peak force of asphalt mixture increases while the fracture energy and CT index decrease.Under the condition of long-term aging,the peak force of 70#matrix asphalt and SBS modified asphalt increases by 31.1%and 15.4%respectively,while the fracture energy decreases by 27.6%and 19.1%respectively.Aging improves the bond strength of asphalt mixture,but the cracking resistance and ductility are weakened.After long-term high temperature water soaking treatment,the peak force,fracture energy and CT index of asphalt mixture are decreased significantly.After four days of high temperature water soaking,the peak force of 70#matrix asphalt and SBS modified asphalt mixture are decreased by 48.2%and 33.1%,and the CT index is decreased by 67.7%and 32.5%,respectively.Water intrusion into the bituminous aggregate interface results in the stripping of the asphalt film,which seriously affects the cohesiveness of the bituminous aggregate interface.