再生骨料及再生骨料混凝土的改性方法是当今学术界和工程界的研究热点。再生骨料改性的核心问题在于如何处理附着在天然骨料上的老砂浆，相比于传统去除老砂浆的方法如酸洗或机械去除，冻融劈裂是一种新的更高效、更环保的物理改性方法。目前针对该方法的研究相对较少，作为原创性探索，本项目将结合实验、理论及细观模拟，探究天然骨料、附着砂浆和界面过渡区的孔隙分布、结冰压力以及冻融作用下的开裂破坏机理；建立界面过渡区受拉软化本构及冻融循环压力下的裂缝开展模型和强度衰减模型；基于粗骨料界面参数，从细观尺度建立再生混凝土力学性能与改性效果间的理论关系；最终针对冻融改性方法建立热力学、孔隙介质力学理论基础，提出最优冻融参数组合。此研究能够为再生粗骨料改性及循环利用提供全新的思路和科学依据，有望发展成为更高效、更环保的生产方法，具有重大的科研意义及工程应用价值。

Recycled aggregate and recycled concrete are very hot topics nowadays. The key problem of recycled aggregate comes from the attached old mortar. Compared to the traditional removing methods such as acid washing and mechanical polishing, freeze-thaw method can be much more efficient and environment friendly. Currently, the mechanism behind freeze-thaw modification method has not been sufficiently investigated yet. As a pilot investigation, this study will combine experimental study, theoretical analysis and mesoscale numerical simulation together to investigate the physical and mechanical mechanisms of this method, which includes the pore size distribution, ice pressure and deformation development during freeze-thaw treatment. Besides, based on the mesoscale parameters of ITZ, the mechanical properties of recycled aggregate concrete will be linked with the modification process. Finally, the thermodynamic and poromechanical theoretical basis will be established to achieve a more efficient modification process. This study can help increasing the efficiency of recycled aggregate modification, which can be of great importance to both the academic and engineering fields.