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出于环境保护及经济方面的考虑,再生骨料在混凝土生产中得到越来越多的应用。混凝土可认为是由天然或再生骨料、多孔基体和界面过渡区三相组成的复合材料。基于随机骨料结构生成算法,建立了三相混凝土数值模型并应用于气体渗透性的分析。对于混凝土二维数值模型的稳态渗透问题,应用有限单元法求解压力场,并基于压力-流量的宏观等效关系计算混凝土材料的总体渗透率。数值分析结果表明:1)总体渗透率随过渡区厚度及其相对渗透率的增加而非线性地增长;2)由于骨料的存在而导致的稀释效应及曲折度效应是影响混凝土总体渗透性的两个重要因素;3)再生骨料渗透率对混凝土宏观渗透率的影响呈“S”形曲线的关系。出于控制回收骨料混凝土渗透性能的考虑,回收骨料的渗透率最好比砂浆基体的渗透率低一个数量级,同时回收骨料的掺量也需要合理选择确定。
For environmental protection and economic considerations, recycled aggregate in concrete production has been more and more applications. Concrete can be considered as natural or recycled aggregate, porous matrix and interface transition zone composed of three-phase composite material. Based on the algorithm of random aggregate structure generation, a three-phase concrete numerical model is established and applied to gas permeability analysis. For steady-state infiltration problem of two-dimensional numerical model of concrete, the finite element method was used to solve the pressure field and the overall permeability of concrete was calculated based on the macroscopically equivalent relationship between pressure and flow rate. The results of numerical analysis show that: 1) the overall permeability increases non-linearly with the increase of transitional zone thickness and its relative permeability; 2) the dilution effect and tortuosity effect due to the aggregate are the factors affecting the overall permeability of concrete Two important factors; 3) the influence of recycled aggregate permeability on the macroscopic permeability of concrete is the curve of “S” shape. For the purpose of controlling the permeability of recycled aggregate concrete, the permeability of recycled aggregate should preferably be one order of magnitude lower than the permeability of mortar matrix, and the dosage of recovered aggregates also needs to be determined and selected reasonably.