高掺量改性RAP热再生沥青混合料低温抗裂性能宏微观机理  

Macroscopic and Microscopic Mechanisms of Low-temperature Crack Resistance of Hot Mix Asphalt With High Content of Rejuvenated RAP

作　　者：郅晓 侯可 张迅 孟凡威 陈宇亮 邓嫔 肖源杰 ZHI Xiao;HOU Ke;ZHANG Xun;MENG Fanwei;CHEN Yuliang;DENG Pin;XIAO Yuanjie(China National Building Material Group Co.,Ltd.,Beijing 100036,China;School of Civil Engineering,Central South University,Changsha 410075,China;Hunan Communications Research Institute Co.,Ltd.,Changsha 410015,China;Ministry of Education Key Laboratory of Engineering Structures of Heavy Haul Railway(Central South University),Changsha 410075,China)

机构地区：[1]中国建材集团有限公司,北京100036 [2]中南大学土木工程学院,长沙410075 [3]湖南省交通科学研究院有限公司,长沙410015 [4]重载铁路工程结构教育部重点实验室(中南大学),长沙410075

出　　处：《北京工业大学学报》2023年第11期1190-1202,共13页Journal of Beijing University of Technology

基　　金：国家重点研发计划资助项目(2019YFC1904704);国家自然科学基金资助项目(52178443)。

摘　　要：旨在研究再生剂和改性剂提升高掺量沥青混合料回收料(reclaimed asphalt pavement,RAP)热再生沥青混合料低温抗裂性能的宏微观机理,进而弥补其低温抗裂性能不足的显著缺陷,设计了3种改性剂配比方案(8%再生剂1、8%再生剂2、4%再生剂2+4%改性剂),开展了高掺量改性RAP热再生沥青混合料室内小梁弯曲试验,分析了混合料的宏观断裂行为特征,进而基于近场动力学理论建立了相应的数值模型,揭示了混合料内部裂纹萌生与扩展的微观机理以及不同改性剂的作用机理。结果表明,双外加剂(再生剂和改性剂)配比下高掺量RAP再生沥青混合料的破坏应变、劲度模量、应变能密度等低温抗裂性能指标均优于单独使用再生剂,近场动力学理论可较好地模拟再生沥青混合料的低温开裂行为;再生剂可显著提升旧沥青界面处的黏结能力,再生剂1使试件底部应力分布更为均匀,再生剂2恢复旧沥青黏结能力的效果更优;而改性剂则提升沥青的整体性能,且对新沥青的性能提升更加明显;相较于单独使用再生剂,双外加剂可恢复旧沥青性能并提升沥青整体的黏性,有效弥补高掺量RAP再生混合料低温抗裂性能不足的缺陷。This paper aimed to study the macroscopic and microscopic mechanisms of modifying and rejuvenating additives for improving low-temperature crack resistance of plant-produced hot mix asphalt(HMA)with high content of reclaimed asphalt pavement(RAP),thereby improving the insufficient low-temperature crack resistance of this material.Three different types of additives(i.e.,regenerant#1 of 8%,regenerant#2 of 8%,and regenerant 2 of 4%+high viscosity additive of 4%)were used to prepare HMA-RAP beam specimens for laboratory three-point bending tests.The macroscopic characteristics of fracture behavior were analyzed.The corresponding peridynamics models of laboratory tests were constructed.The micromechanical mechanisms of internal crack initiation and propagation in HMA-RAP specimens and the mechanisms of different additives improving the low-temperature crack resistance were revealed.Results show that the failure strain,stiffness modulus,strain energy density,and other low-temperature fracture performance indicators of HMA-RAP with both modifying and rejuvenating additives outperform those with rejuvenating additive only.The applicability of peridynamics models was demonstrated in accurate simulations of low-temperature fracture behavior of HMA-RAP.The rejuvenating additive significantly improves the interfacial bonding of aged asphalt.Specifically,the rejuvenating additive No.1 leads to more uniform stress distribution at the bottom of the specimens,while the rejuvenating additive No.2 better recovers the bonding ability of old asphalt.The modifying additive enhances the overall performance of asphalt binder but works better especially for virgin asphalt binder.As compared to the mere use of rejuvenating additive,its combination with modifying additive can recover the performance of aged asphalt binder and improve the overall viscosity of asphalt binder,which improves the drawback of inadequate low temperature crack resistance of HMA-RAP.

关 键 词：沥青混合料 改性RAP 高掺量 热再生 近场动力学 低温开裂 

分 类 号：U414[交通运输工程—道路与铁道工程]