Microstructural analysis of plain and reinforced mortars under chloride-induced deterioration

This paper reports the results of microstructural analysis of plain and steel-reinforced mortar specimens deteriorated by chlorides that were admixed or introduced through chloride ingress. The electrical properties of mortars were measured and their microstructural characteristics were investigated using quantitative image analysis techniques. The influence of chloride ions on mortar microstructure are discussed in terms of hydration and corrosion products. The research reveals that chlorides will induce changes in the chemical compositions and morphology of cement hydration products, and thereby exert influence on ion transport in the mortar specimens. The electrical properties of plain and reinforced mortars are not only related to the presence of chlorides in the pore system but are also influenced by the pore structure characteristics. The cementitious matrix undergoes certain alterations in conditions of the combined effects of: cement hydration, chloride ion transport and chemical binding mechanisms. To this end the pore structure characteristics appeared to be a significantly contributing factor in the process of chloride-induced corrosion in reinforced cement-based materials.