Title: Carbonation-Chloride Interactions and Their Influence Corrosion Rates of Steel in Concrete

Author(s): Harold Roper and Daksh Baweja

Publication: Symposium Paper

Volume: 126

Issue:

Appears on pages(s): 295-316

Keywords: carbonation; cements; chlorides; corrosion; Materials Research

DOI: 10.14359/2177

Date: 8/1/1991

Abstract:
Corrosion of steel reinforcement within concrete structural elements is a major problem in both research and practice. Laboratory studies have been conducted on fundamental mechanisms of corrosion within concrete in the presence of high chloride and others under conditions of reduced alkalinity. However, little has been published on the interactive effects of these two conditions and the ways in which corrosion rates of steel in concrete are thereby influenced. These two conditions occur concurrently under many practical environmental exposures. This paper presents data on methodology used to determine corrosion rates of steel in concrete. Information on corrosion activities in both carbonated and high-chloride environments is presented with reference to mechanisms involved in breakdown of steel passivation. Interactive effects of the two conditions are examined for a range of concrete types and grades. The data suggest that for normal reinforced concrete structural elements, the interactive effects of carbonation and chloride ion ingress lead to much more rapid corrosion than where the two phenomena occur independently. The interactive effects of carbonation and chloride ions as they influence concretes under service conditions are discussed. In particular, the reduction of carbonation rate in the presence of high-chloride ion concentrations is noted.