Durability-related properties of concrete made with chloride-contaminated materials

Because sustainability issues have a primary importance in the construction field, the use of alternative raw materials in concrete production has been widely studied in recent years, especially considering the fact that freshwater is becoming as precious a resource as virgin stones, which are used as aggregates for both concrete and cement production. However, for the durability of reinforced concrete structures, a negligible chloride content in the raw materials should be guaranteed in order to avoid a premature corrosion initiation on reinforcement. Within the Infravation project SEACON, the possible use of recycled aggregate from saltcontaminated concrete structures, seawater- and chloride-contaminated cement have been studied in combination with corrosion-resistant reinforcement for durable concrete structures. Specifically, the experimental study presented in this article is aimed at investigating the effects of chlorides in the raw materials on the durability-related properties of concrete. To this purpose, different concrete mixtures with chloride-contaminated materials were tested in terms of microstructural analysis, mechanical performance, and transport properties (such as compressive strength, capillary water absorption, chlorides, and carbonation penetration). The characterization of concretes showed that the use of chloride-contaminated materials did not negatively influence the early age microstructural features of the hardened cement paste, except for the presence of chlorides in the cement paste. Overall, chloride contamination did not affect the penetration of the carbonation and the capillary absorption, whereas an influence was observed in the resistance to chloride penetration.