Towards sustainability of concrete without chloride limits

This work is part of a project aiming at investigating a new design approach for sustainable and durable concrete structures, which is based on the use of corrosion-resistant reinforcements in order to allow the use of chloride-contaminated raw materials (especially seawater and recycled concrete aggregate (RCA)). Changes in plain concrete properties, as well as the effects on embedded reinforcement (i.e., black steel and glass fiber reinforced polymer (GFRP)) have been studied. Three types of concrete mixes were produced: the first, a standard one, used as the benchmark; the second where freshwater was substituted with seawater; and, the third where chloride-contaminated RCA and seawater were used. For each mix, features of fresh concrete and mechanical properties of hardened concrete were studied. Further information was obtained by microstructural and chemical analyses. Additionally, durability was studied in terms of concrete and reinforcement resistance to aggressive environments. Results show that concrete is not negatively affected by the introduction of seawater in the mix while RCA plays a more important role in concrete properties. As already well established, the use of corrosive reinforcement, such as black steel, is discouraged in chloride-contaminated concrete because of the high corrosion rates due to pitting phenomena.