Influence of surface treatments on corrosion rates of steel in carbonated concrete.

Thirty year old reinforced concrete beams which had been removed from a building were sectioned to provide specimens of convenient size for laboratory investigation of the corrosion rates of the embedded steel reinforcing bars. The concrete was characterised as regards the depths of carbonation at various positions, and examples of steel bars located in regions which were fully carbonated, partially carbonated and not carbonated were identified. Specimens were exposed to a regime of cyclic wetting and drying and the corrosion rates of the embedded bars were monitored by the method of polarisation resistance measurement. Various water repellent surface treatments were applied to the concrete and their abilities to control corrosion were assessed. (A)