Some comments on reinforcement in stagnating saline environments.

Stagnating saline environments can be prone to SRB activity which modifies the chemistry of these waters and therefore influences the aggressiveness of such media towards structural materials. The decrease in pH and concomitant rise in sulphide levels are both parameters of importance to the integrity of concrete and the encapsulated reinforcing steel. The presentation expands on previously published studies in this area by concentrating on mechanistic aspects of steel corrosion in these complex chemical environments. It is seen that competition between the processes that disrupt and restore passivity to the steel surface are a central feature of the electrochemistry of these systems, but are not restricted to chloride-related phenomena. The paper also discusses how corrosion susceptibility is affected by the local pH at the steel-concrete interface, by the anions present, and by oxygen availability. The third section of the paper addresses the effects of concrete-environment interactions on the likely nature of the aqueous medium that are seen by the reinforcing steel in the absence of significant macrocracking, and hence how corrosion reactions can further develop. (A)