微观尺度下温拌再生混合料新-旧沥青界面融合特性

新-旧沥青的有效融合，对再生混合料的使用性能起着决定性作用。深入分析新-旧沥青的扩散过程、量化两者的混合程度，对再生混合料的设计及其性能调节具有极大的实际意义。为了比较真实地模拟新-旧沥青的扩散行为，探讨新-旧沥青界面融合特性，不同混合条件下新-旧沥青融合程度的定量分析、相容渗透剂对新-旧沥青迁移深度的影响。从微观尺度出发，首先模拟温拌再生混合料新-旧沥青融合的三阶段：物理裹附、机械拌合、相互扩散；在分层抽提的基础上，通过凝胶渗透色谱（GPC），获取沥青分子量大小和分布情况，对新-旧沥青融合程度进行量化分析；然后选取合适的分子示踪剂及试验参数，采用傅里叶转换红外光谱（FTIR）研究新-旧沥青的迁移深度，探讨相容渗透剂对新-旧沥青的迁移深度影响。结果表明：大分子比例（LMS）定义的混合效率，可有效定量表征新-旧沥青的融合；无扩散阶段的温拌再生混合料中新-旧沥青的混合效率为29.8%，扩散阶段保温2 h后混合效率达到56.3%，两者的混合效率相差26.5%；对新-旧沥青融合的扩散阶段进行保温，改善了新-旧沥青的融合效果；端氨基丁腈橡胶（ATBN）具有沥青不具有的基团，可以作为适宜的分子示踪剂；添加渗透性良好的相容渗透剂可增加旧沥青的渗透深度，当分层抽提层数为3层时，未加相容渗透剂，新-旧沥青迁移深度为2层，添加相容渗透剂后，迁移深度增加为3层。

Study on Interfacial Fusion Characteristics of Virgin and Aged Asphalt of Warm Mix Recycled Mixture at Micro Scale

The extent of blending between virgin and aged binders plays a decisive role in the performance of recycled mixtures. Analyzing the diffusion process of virgin and aged binders and quantifying their mixing degree are of great practical significance for the design and performance adjustment of recycled mixtures. To simulate the diffusion behavior of virgin and aged binders, their interface fusion characteristics were explored:the quantitative fusion degree of virgin and aged binders under different mixing conditions and influence of compatible penetrant on the migration depth of virgin and aged asphalt. In this study, the three stages of virgin and aged binder fusion of warm mix recycled mixture were simulated at the microscopic scale:physical binding, mechanical mixing, and mutual diffusion; based on the stratified extraction, the molecular weight and distribution of bitumen were obtained by gel permeation chromatography (GPC), and the degree of fusion between the two kinds of asphalt was quantitatively analyzed. Then, suitable molecular tracers and test parameters were selected to study the migration depth of the virgin and aged binders using Fourier transform infrared spectroscopy (FTIR), and the influence of compatible penetrant on the migration depth of virgin and aged asphalt was discussed. The results show that the mixing efficiency defined by the macromolecular ratio (LMS) can effectively and quantitatively characterize the fusion of virgin and aged asphalt; the mixing efficiency of the virgin and aged asphalt in the warm mix recycled mixture was 29.8% in the non diffusion stage, and 56.3% after 2 h of heat preservation in the diffusion stage, with a difference of 26.5%. In the diffusion stage of the virgin-aged asphalt fusion, heat preservation is beneficial for improving the fusion of the virgin-aged asphalt. Amino-terminated butadiene acrylonitrile rubber (ATBN) can be used as a suitable molecular tracer because it has groups that asphalt does not have, and adding compatible penetrants with good permeability can increase the penetration depth of aged asphalt. When there are three extraction layers, without a compatible penetrant, the migration depth of the virgin and aged binder is two layers. After adding a compatible penetrant, the migration depth increased to three layers.