This report describes a laboratory investigation to compare the protection provided against chloride-induced corrosion of embedded steel by a number of repair materials. Specimens made from twelve types of repair material were exposed to chlorides and the time to corrosion and corrosion rates of embedded steel bars determined. Control specimens of a good and a moderate quality concrete were also assessed. The results highlight differences in performance between the materials and show that some provide good protection against chloride induced corrosion. Six of the repair materials (10mm aggregate concrete, glass granulated blast furnace slag (GGBFS) concrete, flowing concrete, acrylic-modified mortar, styrene butadiene rubber (SBR) modified mortar, lightweight epoxy resin mortar) were used to repair cavities cast into small reinforced concrete slabs. The slabs were exposed to chlorides and the time to corrosion and corrosion current flowing between embedded bars determined. The performance of the interface between the parent concrete and repair material was shown to be critical, allowing relatively easy ingress of chloride in many cases. Initiation of corrosion was frequently much earlier than would have been expected from the results of single material specimens, with intense anodic sites forming on the steel at the interface. (A)

Want to know more about this project?