Ionic transport features in concrete composites containing various shaped aggregates: a numerical study

The service life of concrete-based infrastructure and buildings is seriously shortened due to the chloride-induced durability problems. In order to clarify the transport mechanism associated with the response of inclusion structures, this paper presents a numerical study on the influence caused by morphology and heterogeneity of individual phases, in which the concrete is treated as a three-phase composite including mortar, aggregates and interfacial transition zone (ITZ). A series of meso-scale numerical models with different shapes and volume fractions of aggregates are developed for examining the effects of aggregates on ionic migration. Unlike in most of the existing published research work in this area, a multi-component ionic transport theory which takes ionic interactions into consideration has been utilised in this study. By coupling mass conservation and Poisson's equations, the time-spatial concentration distribution results for individual ionic species are obtained. Other important factors such as the externally applied electric field, concrete heterogeneity, ionic binding and ITZ are also considered and examined in this study. Through this relatively thorough numerical analysis, some important features about the effect of aggregate shape based on multi-species modelling, which have previously not been properly investigated, are highlighted.