Electrical resistance to monitor carbonation and chloride ingress

Electrical resistance (R) of concrete is sensitive to changes in the chemical phases and physical structure of hydrated cement paste, moisture content, and the physical structure of concrete. Therefore, R is influenced by both carbonation and chloride ingress. However, in a structure subjected to a combination of carbonation and chlorides, in which there are complex changes to both physical and chemical characteristics of hydration products, the use of electrical resistance measurements to assess the durability of concrete is still limited. In this investigation, four different combinations of carbon dioxide and chloride exposure regimes were used to examine the relationship between the electrical resistance, degree of carbonation, and quantity of chlorides (or chloride content). It has been found that for concretes with a stabilized relative humidity, the electrical resistance is sensitive to cement hydration and variations in chloride content in both independent chloride exposure regime and combined chloride and carbonation regime. However, the relationship between electrical resistance and the degree of carbonation is not that pronounced for accelerated carbonation test regime for 3 months.