基于单轴贯入重复剪切试验的沥青混合料永久变形

Research on Asphalt Mixture Permanent Deformation by Single Penetration Repeated Shear Test

沥青路面车辙变形越发严重,降低路面使用寿命的同时大大影响行车安全.通过对比分析,提出运用单轴贯入重复剪切试验研究沥青混合料的永久变形.对高速公路沥青路面上中面层最常用的4种沥青混合料进行了不同荷载水平下的单轴贯入重复剪切试验,得到如下结论:单轴贯入重复剪切试验可以做出沥青混合料的三阶段变形;荷载越大混合料永久变形的速率越大,剪切疲劳寿命或流动数越小,当荷载大于或等于1.3MPa时改性沥青混合料在较小的荷载次数内变形过大,发生剪切破坏,而当荷载小于或等于1.1MPa时变形增加极慢,稳定地处于变形的第二阶段而不破坏;抗剪强度较大的沥青混合料抵抗剪切变形的能力较强,改性沥青混合料抵抗剪切变形的能力远大于普通沥青混合料;荷载应力水平和作用次数具有等效性.

The pavement rutting is getting worse,which shortens the pavement service life,and the driving safety is therefore affected.A single penetration repeated shear test(SPRST) was proposed for a research on asphalt mixture permanent deformation on the basis of a comparative analysis.Many SPRST tests on different load levels were made with four kinds of the most commonly used asphalt mixtures in the upper and middle layer of asphalt pavements.Test results show that the three-stage permanent deformation behavior of asphalt mixtures on loads can be obtained by SPRST.The bigger the load is,the faster the permanent deformation of asphalt mixtures increases and the smaller the shear fatigue life or the flow number is.A larger load(≥1.3 MPa) brings about large deformation without large load cycles and the mixture breaks;but the smaller load(≤1.1 MPa) gives rise to a slow increase of deformation,which is stable in the second stage.The asphalt mixtures with bigger shear strength have a greater ability to resist the shear deformation than conventional asphalt.Load stress levels are equivalent to load cycles.