后生产阶段时-温耦合作用对RHAM水稳定性的影响

为揭示热再生沥青混合料(RHAM)在后生产阶段新旧沥青混融程度演变及其对RHAM水稳定性的作用，在调研后生产阶段中RHAM的温度耗散规律与耗时的基础上，以时-温当量为指标构建了4种典型后生产阶段工况，采用Pb标记新加沥青，借助能谱仪分析了时-温当量对新旧沥青融合的促进作用；通过沥青混合料水敏感性试验模拟了轮胎运行作用下雨水对再生沥青路面的冲刷效应，解析了时-温当量与RHAM在动水冲刷条件下水稳定性的定量关系；对比了5个厂拌热再生沥青路面工程中7种RHAM在后生产阶段前后的强度差异，并论证了时-温当量对再生沥青路面压实度的影响。研究结果表明：后生产阶段中新旧沥青的融合程度与时-温当量呈正比关系；提高时-温当量可抑制动水冲刷下RHAM的空隙发育，从而改善其水稳定性；时-温当量每提高10%，RHAM在未冲刷和弱、中、强冲刷下的马歇尔稳定度分别增大了0.86%、2.94%、2.13%和3.34%，冻融前后的劈裂强度分别提高了1.24%和0.21%；RHAM经历后生产阶段后的稳定度均较之前有显著提高，增幅介于9.0%~32.4%；在保证压实温度和规范施工的前提下，时-温当量与压实质量之间没有必然联系，考虑到时-温当量对RHAM的性能改善作用，建议在保证压实温度的前提下设法延长后生产阶段。

Effect of time-temperature coupling on moisture stability of RHAM in post-production stage

To reveal the evolution of blending degree of aged and virgin asphalt in the post-production stage of recycled hot-mix asphalt mixture (RHAM) and its effect on the moisture stability of RHAM, the temperature dissipation law and time consumption of RHAM in the post-production stage were investigated, and four typical post-production stage working conditions were constructed, with the time-temperature equivalent as the indicator. The effect of time-temperature equivalent on promoting the blending of aged and virgin asphalt was revealed by using Pb to identify the virgin asphalt, with the help of the energy dispersive spectrometer analysis. The scouring effect of rainwater on the recycled asphalt pavement under the action of tire running was simulated through the moisture-induced sensitivity test of asphalt mixture. The quantitative relationship between the time-temperature equivalent and the moisture stability of RHAM under the dynamic water scouring conditions was analyzed. The strength differences of seven types of RHAMs before and after the post-production stage in five plant-mixed hot recycled asphalt pavement projects were compared, and the effect of time-temperature equivalent on the compaction of recycled asphalt pavement was demonstrated. Research results show that the blending degree of aged and virgin asphalt is directly proportional to the time-temperature equivalent in the post-production stage. The void development of RHAM under the dynamic water scouring can be prevented by increasing the time-temperature equivalent, so as to improve its moisture stability. As the time-temperature equivalent increases by 10%, the Marshall stabilities of RHAM under unscoured, weak, medium, and strong scouring conditions increase by 0.86%, 2.94%, 2.13%, and 3.34%, respectively, and the splitting strengths before and after freeze-thawing increase by 1.24% and 0.21%, respectively. The stability of RHAM after the post-production stage improves significantly, with the increase amplitude ranging from 9.0% to 32.4%. Under the premises of ensuring the compaction temperature and standardized construction, there is no inevitable relationship between the time-temperature equivalent and the compaction quality. Since the time-temperature equivalent can improve the performance of RHAM, it is recommended to extend the post-production stage under the premise of ensuring the compaction temperature.