Diffusion of deleterious substances through concrete can severely affect its life. The widely varying constituent length scales of concrete contains micron-sized pores with centimetre-sized aggregates making diffusion a complex phenomenon. This study describes a multiscale model investigating factors of important concrete matrix constituents: pores and aggregates, including their interfaces on the diffusion behaviour of concrete. A finite difference in time domain model has been developed to study the diffusion through the representative element consisting of cement matrix and aggregates. The model has been validated with existing experimental results. Numerical relationships are established between diffusion coefficients with different casting parameters of concrete. It is observed that the net porosity and the aggregate ratio has a higher significance on the diffusion coefficient than the size and arrangement of aggregates and the ITZ. The study facilitates analysis of pore structures for diffusivity and durability of concrete to achieve improved lifecycle performance.

有害物质通过混凝土扩散会严重影响其寿命。混凝土的组成长度尺度变化很大，包含微米级的孔隙和厘米级的骨料，使扩散成为一个复杂的现象。这项研究描述了一个多尺度模型，该模型研究了重要的混凝土基体成分的因素：孔隙和聚集体，包括它们对混凝土扩散行为的影响。已经开发了时域有限差分模型，以研究通过包括水泥基质和集料在内的代表性元素的扩散。该模型已通过现有实验结果验证。建立了不同混凝土浇筑参数的扩散系数之间的数值关系。可以看出，净孔隙率和骨料比率对扩散系数的影响比骨料和ITZ的大小和排列更高。该研究有助于分析孔结构的混凝土扩散性和耐久性，从而改善生命周期性能。