沥青混合料永久变形的三轴重复荷载试验研究

采用半正矢波间歇荷载,进行了4种不同沥青混合料的三轴重复加载永久变形试验.以流动数为评价指标,研究混合料性质(级配组成、沥青用量和空隙率)、试验温度和应力水平对混合料高温性能的影响,对永久应变与荷我作用次数的关系进行非线性回归分析,提出了能够全面反映重复荷载下沥青混合料的永久变形特性的模型.结果表明:AC16流动数最高,AC13C次之,而AC20和AC13F流动数相对较小;沥青用量增加0.5%,流动数下降20%～30%;空隙率从4%增加到7%,流动数下降50%左右,应力水平越大,温度越高,流动数越小,而降低幅度也减小;在极端高温和重载下,不同沥青混合料的流动数较小,其变化幅度不大,不足以明显区分混合料的高温性能.

Research on Permanent Deformation of Asphalt Mixture by Triaxial Repeated Load Test

Triaxial repeated load permanent deformation tests of AC13F, AC13C, AC16 and AC20 under interim haversine loading were conducted.The flow number was selected as an evaluation index to investigate the influences of asphalt mixture characteristic including gradation, asphalt content, air voids, stress and temperature on the high-temperature performance of asphalt mixture.It is indicated that (1) flow number of AC16 is the highest, then is that of AC13C, but the AC13F and AC20 have the smaller ones; (2) with asphalt content increases by 0.5% , the flow number decreases by 20%～30% ; (3) with air voids increases from 4% to 7% , the flow number also decreases by about 50%; (4) the flow number also decreases with smaller decrease range at the higher stress and temperature; and (5) the flow numbers of asphalt mixtures are very small at the extreme stress and temperature, and the difference among them is inconspicuous which could not be used to distinguish high-temperature performance of the asphalt mixtures.Finally, the relationship between permanent strain and loading cycle was analyzed by the nonlinear regression method to describe the permanent deformation of asphalt mixture under repeated load comprehensively.