砂粒式防水沥青混合料低温弯曲蠕变试验分析

试验选用沥青用量分别为4%,5%,6%,7%和8%的砂粒式防水沥青混合料AC—5的上限级配、中值级配和下限级配3种级配类型,在温度为0℃条件下进行加载量分别为50,100和200N的弯曲蠕变试验。试验结果表明:沥青用量超过约5%后,依靠提高沥青用量改善沥青混合料的低温抗裂性能效果甚微;加载量为100N时,试件跨中弯曲蠕变速率大于加载量50和200N所对应的弯曲蠕变速率;3种级配的沥青混合料弯曲蠕变速率为下限级配大于中值级配,中值级配大于上限级配。根据试验结果的综合分析并考虑低空隙率、高防渗性等技术要求,关于防水用砂粒式沥青混合料适宜的级配类型建议选用中值级配。

Test Analysis on the Bending Creep of the Granular Impermeable Asphalt Mixture in Low Temperature

This paper analyzes the bending creep test in low temperature (0 ℃) under different loading (50, 100 and 200 N) by choosing AC-5 with three representative grading types (near to the upper limit, median and lower limit of the grading range in specification) and different asphalt contents (4%, 5%, 6%, 7% and 8%). The test results show that the effect to improve the anti-cracking performance of the asphalt mixture in low temperature is little by increasing the asphalt content especially when the asphalt content exceeds 5%. The bending creep rate in the middle of the beam span is larger under 100 N loading than that under 50 and 200 N. The bending creep rate of the specimens with three grading types near to the lower limit is larger when compared to those with design grading near to the median and the upper limit (smallest). As required by low air voids and high impermeability, it is suggested that the median limit grading type should be adopted for the granular impermeable asphalt.