基于界面参数的普通与再生骨料混凝土结构构件时变性能差异及机理研究

It is of vital importance to recycle the large amount of waste concrete, to ensure the sustainable development of the construction industry. Compared with natural aggregate concrete (NAC) structures, however, recycled aggregate concrete (RAC) structures are generally inferior in their structural performance and durability. The predominant reason for such inferiority lies on the more types and larger amount of interface transition zones (ITZ) in RAC than in NAC, which presents the essential difference between the two categories of concrete on the micro scale, as well. Till now, no integrated interface parameters which are able to reflect multi interface properties of RAC have been reported yet. Moreover, the relation between the selected interface parameters and the material properties and structural performance of RAC has not been described quantitatively, either. Therefore, this study focuses on how the interface properties of NAC and RAC on the micro scale can influence the material properties and structural performance on the macro scale. It is also the main concern of this research to reveal the geometric and mechanical features of different types of ITZs contained in RAC and NAC, and thereby to select out the proper interface parameters which are physically reasonable and meanwhile can reflect multi interface properties comprehensively. Based on the selected multi interface parameters, this study aims to establish the degradation models of RAC's properties on both the material scale and the member scale, and moreover, to reveal the mechanism of the differences in the degradation process of reinforced RAC and NAC members and structures. The output of this project will not only help reveal the degradation models of RAC materials and structures and the corresponding mechanism, but also contribute to the supplement of the theory system of concrete study.

废混凝土循环利用是建设行业可持续发展的重要路经；但相比普通混凝土结构，再生骨料混凝土结构性能水平更低、耐久性更差，其根本原因在于：再生骨料混凝土存在更多更复杂的界面薄弱环节，这也是再生骨料混凝土与普通混凝土在细微观尺度上的本质差异。现阶段研究尚未能提出可反映再生骨料混凝土内多类骨料界面的综合性能参数，亦无法建立再生混凝土骨料界面参数与其宏观性能的关系。因此，本项目拟从不同空间尺度出发，探索“骨料界面性能－宏观材料性能－结构构件性能”的性能传递逻辑关系；研究再生骨料混凝土各类骨料界面几何及力学性能特征，确立反映界面综合性能具有物理意义的骨料界面参数；基于界面参数，研究再生骨料混凝土材料与构件性能时变劣化规律，揭示普通与再生骨料混凝土结构构件时变性能差异及其机理。本项目的研究工作可弥补再生骨料混凝土材料及构件在性能劣化模型构建及机理解释方面的不足，且对完善混凝土理论研究体系亦具有重要意义。

在建筑行业的飞速发展的过程中，建筑固废的大量排放引发了严重的环境问题和社会问题。将建筑固废回收制备成再生骨料，并替代天然骨料浇筑成混凝土制品，是解决这一问题的途径之一。而再生骨料表面粘附的老砂浆在再生骨料混凝土内引入了种类和数量更多的界面过渡区，从而导致了再生骨料混凝土的力学性能和耐久性能更差。但是，目前已经取得的研究成果，尚未能基于再生骨料混凝土内各类界面过渡区的性能，定量性地建立再生骨料混凝土界面过渡区性能与其宏观性能的关系。因此，本项目从不同空间尺度，探索了再生骨料混凝土内界面过渡区、宏观材料性能和结构构件性能的时变规律：研究了再生骨料混凝土内各类界面过渡区的几何特征和力学性能特征，并建立了能反映界面过渡区综合性能且具有物理意义的界面参数；研究了普通与再生骨料混凝土的宏观材料性能的时变规律，并实现了对宏观材料性能的预测；研究了锚固加载和氯盐干湿循环共同损伤下再生骨料混凝土梁、柱的性能劣化规律，揭示了普通与再生骨料混凝土构件性能的差异。本项目的研究工作弥补了再生骨料混凝土材料及构件性能的时变规律的不足，同时以界面过渡区的性能定量地揭示了再生骨料混凝土性能裂化的机理，对完善混凝土理论研究体系有重要的意义。