低应力水平下混凝土中氯离子扩散行为多尺度分析方法

发布时间：2018-06-19 14:00

本文选题：混凝土 + 氯离子扩散行为　；参考：《工程力学》2017年03期

【摘要】：混凝土的扩散渗透性能与其微观结构(包括细观尺度上粗骨料颗粒与砂浆之间的界面过渡区及砂浆本身的微观结构等)密切相关。在微观尺度上,砂浆和界面过渡区均可视为由无孔砂浆基质和孔隙水夹杂相组成的两相复合材料,二者的主要区别表现为孔隙率不同。在外荷载作用下,砂浆和界面过渡区的毛细孔隙率及孔隙连通性会发生改变,从而改变混凝土的扩散渗透性能。基于此,该文建立了低应力水平下混凝土中氯离子扩散行为多尺度理论分析方法,获得了混凝土表观扩散系数与外荷载(以体应变表征)及砂浆和界面过渡区当前孔隙率的定量关系。分析所采用的主要参数为砂浆和界面过渡区的毛细孔隙率、无孔砂浆基质和骨料相的力学参数、骨料相和界面过渡区的体积分数、外荷载等。与已有文献数据对比知,该文分析结果与之吻合良好,表明了理论分析方法的合理性与准确性。此外,基于该方法,探讨分析了混凝土微/细观结构对其宏观扩散性能的影响。
[Abstract]:The diffusion and permeability properties of concrete are closely related to its microstructure (including the interfacial transition zone between coarse aggregate particles and mortar and the microstructure of mortar itself on a mesoscale scale). On the micro scale, the mortar and the interfacial transition zone can be regarded as two-phase composites composed of porous mortar matrix and pore water inclusion phase. The main difference between them is that the porosity is different. Under external load, the capillary porosity and pore connectivity of mortar and interfacial transition zone will be changed, which will change the diffusion and permeability of concrete. Based on this, a multi-scale theoretical analysis method of chloride ion diffusion behavior in concrete at low stress level is established in this paper. The quantitative relationship between the apparent diffusion coefficient of concrete and external load (represented by bulk strain) and the current porosity of mortar and interfacial transition zone is obtained. The main parameters used are capillary porosity of mortar and interfacial transition zone, mechanical parameters of porous mortar matrix and aggregate phase, volume fraction of aggregate phase and interfacial transition zone, external load and so on. Compared with the existing literature data, the results of this paper are in good agreement with them, which indicates the rationality and accuracy of the theoretical analysis method. In addition, based on this method, the influence of micro / meso structure of concrete on its macroscopic diffusivity is discussed.
【作者单位】：北京工业大学城市与工程安全减灾教育部重点实验室;清华大学土木工程系;
【基金】：973计划项目(2011CB013600) 国家自然科学创新群体项目(51421005) 国家自然科学基金项目(51508011) 中国博士后科技基金项目(2015M570105)
【分类号】：TU528

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