基于OT试验的大粒径沥青混合料抗裂性能研究

Study on crack resistance of large size asphalt mixture based on OT test

为了研究大粒径沥青混合料作为沥青路面下面层抵抗反射裂缝的能力,研究了其在不同荷载速率、不同温度、不同油石比和不同老化情况下的抗裂性能。通过OT试验对大粒径沥青混合料进行单调拉伸试验并对其断裂面分形特性进行研究,测出其在不同条件下的荷载位移曲线,得出不同条件下的力学性能参数和分形维数。研究结果表明:大粒径沥青混合料在不同条件下表现出很好的分形特性,分形维数越高表明断裂能越高;总断裂能和裂缝扩展阶段的能量随温度的降低、油石比的增大、加载速率的提高和老化程度的增加而增大;峰值荷载和断裂能指数随加载速率增加和温度的降低而增加。推荐用总断裂能和分形维数评价大粒径沥青混合料的抗裂性能,以提高试验重复性。断裂能指数对沥青混合料断裂性能评价的有效性还有待进一步研究。

In order to study the anti-reflective cracking ability of large-size asphalt mixture as the underlying layer of asphalt pavement,its anti-cracking performance was studied under different load rates,temperatures,bitumen-aggregate ratios and aging conditions.Through OT test,the monotonic tensile test of large size asphalt mixture was carried out and its fractal characteristics was studied.Load-displacement curves was measured under different conditions,and mechanical properties parameters and fractal dimensions were obtained under different conditions.The results show that the large-size asphalt mixture has good fractal characteristics under different conditions,and the higher the fractal dimension is,the higher the fracture energy is;the total fracture energy and the fracture energy in propagation stage increase with the decrease in temperature as well as the raise in bitumen-aggregate ratio,loading rate and aging degree;and the peak load and fracture energy index increase with the increase in loading rate as well as the the decrease in temperature.It is recommended that the total fracture energy and fractal dimension be used to evaluate the crack resistance of large size asphalt mixture in order to improve the repeatability of the test.The effectiveness of fracture energy index in evaluating the fracture properties of asphalt mixtures needs further study.