基于界面接触效应的新旧集料复合骨架流变行为及力学表征

The interfacial contact effect of old and new aggregates significantly affects the rheological properties of recycled asphalt mixture. The mechanical characteristics, quantity and spatial distribution of the interfaces in the composite skeleton influence the consistency of the skeleton deformation, which in turn affects the rheological properties of the material. At present, the main factors that affect the contact effect of the interface have not yet been clarified, and it still lacks of relevant test methods, leading to a fact that the influence of the interface contact effect on the rheological properties of the composite skeleton has not been clearly understanding. In this research, the strength formation and the new and old aggregate composite skeleton deformation of the recycled asphalt mixture are studied through the meso - macro cross scale. A particle contact interface strength shear test system is developed to study the interfacial mechanical strength of old and new aggregate particles, based on that a elastic stiffness model of contact interface is deduced including the performance of asphalt, the angularity of the aggregate and the asphalt film fusion state of the interface as the parameters according to granular mechanics theory. The relationship between the interface strength and the macroscopic rheological properties of the skeleton-density recycled asphalt mixture is studied to establish the granular rheological model. The effects of RAP content on the interface strength and the overall rheological properties of the composites are studied to determined the limit ratio of RAP, based on that a mix design method for skeleton-density hot recycled asphalt mixture is summarized. The research results can be used to guide the design and construction of skeleton-density hot recycled asphalt mixture, and improve the technical level of asphalt mixture recycling.

新旧集料的界面接触效应显著影响再生沥青混合料的流变性能。复合骨架中各类接触界面的力学特征、数量和空间分布制约了骨架变形的一致性，进而左右了材料的流变性能。目前尚未明晰影响界面接触效应的主要因素，缺乏相关的试验手段，无法认清界面接触效应对复合骨架流变性能的影响。本项目从细观-宏观跨尺度研究再生沥青混合料的强度形成和新旧骨架变形。开发接触界面强度剪切试验系统，开展新旧集料的界面力学研究，基于散体力学理论推导以沥青性能、集料棱角性和界面沥青膜融合状态为参数的接触面弹性刚度模型；研究接触界面强度与骨架密实型热再生沥青混合料宏观流变性能的相关关系，建立散体流变模型；研究集料RAP掺量对接触界面强度以及材料整体流变性能的影响，确定RAP的极限掺配比例，在此基础上形成骨架密实型热再生沥青混合料的配合比设计方法。研究成果可用于指导骨架密实型热再生沥青混合料的设计与施工，提高沥青混合料再生利用水平。

研究沥青混合料再生料（RAP）对混合物细观-宏观物理力学性能的影响及其控制方法，是实现再生沥青混合料路用性能提高的重要基础。本项目基于数字图像技术分析了再生沥青混合料的新旧骨架，得到不同RAP掺量下的骨架特征参数，提出基于复合骨架参数的最佳RAP掺量设计理念；研发了“沥青混合料颗粒剪切分析系统”，确定了剪切试验的合理参数，发现剪切应力曲线表现出典型的“预剪切阶段”、“剪切稳定阶段”和“剪切破坏阶段”三段式增长；对不同岩性的集料和不同RAP掺量的再生沥青混合料进行了界面剪切试验与单轴贯入试验，建立了级配、集料类型、RAP掺量与颗粒接触界面剪切力、界面切向弹性刚度和混合料的剪切模量之间的相关模型；建立了基于骨架特征分析与界面力学参数的剪切模量预估模型，并验证了模型的合理性。项目研究结果表明，充分考虑再生沥青混合料的非均质特征是实现RAP高效利用的重要前提。