Seawater and stainless steel bars for sustainable reinforced concrete structures

In Mediterranean countries seawater might become a resource for the concrete production for sustainable construction industry. Nowadays its use, since it might induce the corrosion on ordinary carbon steel bars, is prohibited for the realization of reinforced concrete structures. Within the SeaCon Project, the use of seawater as mixing water has been studied in combination with corrosion-resistant reinforcement. This paper, firstly, discusses the influence of chlorides present in the seawater on the concrete properties related to the durability. Afterwards, the corrosion resistance of austenitic (304L and XM-28) and duplex (23-04 and 22-05) stainless steels reinforcing bars, and for comparison of carbon steel, embedded in alkaline and carbonated concretes made with seawater and subjected to different environmental conditions is evaluated. Results showed that seawater accelerated the early strength of concrete, whilst the carbonation penetration, the capillary suction and water absorption were slightly affected. Corrosion tests showed that corrosion did not initiate on 304L, 23-04 and 22-05 stainless steel bars, despite the presence of chlorides since the beginning even in the most aggressive exposure conditions and when concrete was carbonated; XM-28 reinforcement showed a slight change in corrosion behaviour in carbonated concrete exposed to the harshest conditions.