基于三点弯曲试验的ATB-25弯拉特性的研究

Research on Flexural-tension Properties of ATB-25 Using Three-point Bending Test

通过沥青稳定碎石基层ATB-25沥青混合料的三点弯曲试验，研究了温度及加载速率对弯拉强度、弯拉应变及弯曲劲度模量的影响规律。在较大试验温度范围内，施加两组加载速率对ATB-25沥青混合料小梁试件的弯拉特性进行试验研究。结果表明：高加载速率条件下试件破坏的弯拉强度大于低加载速率下的弯拉强度；温度越高，高低荷载速率之间的弯拉强度差别越大。低荷载速率条件下的弯拉应变约为高荷载速率下的1．5—2．5倍，且在温度低于25℃时，小梁试件的弯拉应变与温度之间有较好的指数变化规律。同时，其弯曲劲度模量与温度之间也呈现良好的指数关系。对比分析了高低荷载速率条件下的指数回归方程参数，表明了低荷载速率条件下的ATB-25沥青混合料表现出较佳的抗裂性能。通过对小梁试件破坏前的弯曲应变能的计算，可得知其在常温域（15℃）附近具有最大的弯曲应变能。

Effects of temperature and loading rate on the flexural-tensile strength, strain and stiffness modulus of ATB-25 asphalt mixture were discussed using three-point bending test.Tests were conducted on ATB-25 asphalt mixture beam specimens over a wide range of temperature to investigate the variety of properties from low loading rate to a relatively high loading rate. Experimental results show that （ 1 ） flexural strength at high loading rate is larger than that at low loading rate; （2） flexural strength differences between high and low loading rates become larger when the temperature rises; （3） flexural-tensile strain at low loading rate increased to 1.5 to 2.5 times compared with that at high loading rate, which follows an exponent-law as temperature lower than 25℃; （4） flexural modulus also shows an exponent-law relation with temperature.Parameters from exponent-law regressive equation of the flexural modulus were compared between the two loading rates, which show that ATB-25 asphalt mixture exhibits better anti-cracking characteristic at low temperature when given a relatively low loading rate. ATB-25 asphalt mixture exhibits highest curvature strain energy around normal temperature （15 ℃） on the basis of the calculation of the state before the beam specimens damaged.