ELECTROCHEMICAL INDUCTION OF ALKALI SILICA REACTION IN CONCRETE

The use of cathodic protection as a method of countering chloride-induced corrosion of steel in concrete causes the formation of hydroxyl ions at the surface of the embedded metal. The preliminary experiments described in this note were aimed at evaluating a possible side-effect of this process under circumstances where the concrete contains a potentially reactive aggregate. For concrete specimens containing calcined flint aggregate, it was shown that deleterious local expansion of the material was generated owing to alkali-silica reaction induced in the vicinity of embedded steel when the latter was subjected to potentiostatic polarization for a period of several months at -850 mV (SCE scale). Continuing investigations are aimed at providing further insight into this phenomenon to aid the assessment of its practical implications.