冻融循环对再生沥青混合料低温抗裂性能的影响研究

Research on Influence of Freezing and Thawing Cycle on Low-temperature Anti-cracking Ability of Recycled Asphalt Mixture

从沥青路面低温裂缝产生的原因入手,分析了裂缝类型和裂缝的影响因素及其对道路的危害。为了研究冻融循环对再生沥青混合料的低温抗裂性能的影响,采用小梁低温弯曲试验进行研究,再生沥青混合料的级配为AC-16和AC-20,研究的冻融试验方案是根据研究所在地气候特点及相关文献的冻融试验方法确定,冻融循环次数分别为0、6、9和12次。对比不同冻融循环次数对再生沥青混合料的弯拉应变试验结果的影响,结果表明,随着冻融循环次数的增加,再生沥青混合料的弯拉应变逐渐减小,并且随着旧料掺量的增加,再生沥青混合料受到冻融循环的影响越大;级配AC-20与级配AC-16相比,级配AC-20受到冻融作用的影响更显著;通过分析低温弯曲试验结果变化规律,AC-16的最佳旧料掺配率是19. 8%,AC-20的最佳旧料掺配率为16. 4%,这样既能够确保道路使用的寿命又能尽可能多地利用旧料。

Starting from the reason for low-temperature crack of asphalt pavement,the influencing factor of crack type and crack and its hazard to the road are analyzed. In order to study the influence of freezing and thawing cycle on the low-temperature anti-cracking ability of recycled asphalt mixture,the research on the low-temperature bending test for small beam is made. The gradation of recycled asphalt mixture is respectively AC-16 and AC-20. The freezing and thawing test scheme is determined according to the freezing and thawing test methods of climatic feature and relevant literature,and the times of freezing and thawing cycle are respectively 0,6,9 and 12. The influence of different times of freezing and thawing cycle on the result of flexural-tensile strain test of recycled asphalt mixture is compared. The result shows that: with the increase of times of freezing and thawing cycle,the flexural-tensile strain of recycled asphalt mixture gradually decreases,and with the increase of mixing amount of old material,the influence of freezing and thawing cycle on the recycled asphalt mixture is larger;comparing the gradation AC-20 and AC-16,the influence of freezing and thawing on the gradation AC-20 is more remarkable. The optimum proportion of old mixture of AC-16 is 19. 8% and that of AC-20 is 16. 4% by analyzing the change rule of low-temperature bending test result,which can not only guarantee the service life of road usage but also utilize the old material as much as possible.