Abstract: To compare the effects of two RAP pretreatment techniques, namely fine separation and conventional crushing, on the performance of recycled ultra-thin overlay mixtures, the road performance of these mixtures under these two pretreatment techniques was first evaluated. Furthermore, based on SEM and molecular simulation, interface models of new-old asphalt and recycled asphalt-aggregate in the mixture were established, and the interface performance was comparatively evaluated. The research results show that compared with the conventional crushing technique, the ultra-thin overlay mixtures prepared by fine separation technique exhibit better moisture stability, low-temperature crack resistance (at 50% RAP content, the residual stability and flexural tensile strain increase by 5.7% and 5.3%, respectively) and interface performance (the bonding performance of new-old asphalt interface and asphalt-aggregate interface increases by 21.0% and 29.3%, respectively), but slightly worse high-temperature performance (at 50% RAP content, the dynamic stability decreases by 5.5%). Considering meeting the road performance standards, the RAP content of recycled ultra-thin overlay mixtures under conventional crushing technique is 30%, while that under fine separation technique can reach 50%.

Key words: road engineering; RAP; ultra-thin overlay mixtures; fine separation; road performance; molecular simulation

摘要： 为了对比精细分离与常规破碎这两种RAP预处理技术对再生超薄罩面混合料性能影响，首先评价了这两种技术下再生超薄罩面混合料的路用性能；进而基于SEM扫描电镜及分子模拟，建立了混合料中新-旧沥青以及再生沥青-集料的界面模型，并对比评价其界面性能。研究结果表明：与常规破碎技术相比，精细分离技术下的超薄罩面混合料具有更好的水稳定性、低温抗裂性能(50%掺量下残留稳定度与弯曲抗拉应变分别提升5.7%与5.3%)和界面性能(新旧沥青界面与沥青-集料界面黏结性能分别提升21.0%和29.3%)，但高温性能稍差(50%掺量下动稳定度下降5.5%)；基于路用性能达标考虑，常规破碎技术下再生超薄罩面混合料的RAP掺量为30%，精细分离技术可达50%。

关键词: 道路工程；RAP；超薄罩面混合料；精细分离；路用性能；分子模拟