Reinforcement corrosion initiation and activation times in concrete structures exposed to severe marine environments

Li, Chun-Qing and Melchers , Robert E. (2009) Reinforcement corrosion initiation and activation times in concrete structures exposed to severe marine environments. Cement and Concrete Research, 39 (11). pp. 1068-1076. ISSN ISSN: 0008-8846

Abstract

The corrosion of steel reinforcement bars in reinforced concrete structures exposed to severe marine environments usually is attributed to the aggressive nature of chloride ions. In some cases in practice corrosion has been observed to commence already within a few years of exposure even with considerable concrete cover to the reinforcement and apparently high quality concretes. However, there are a number of other cases in practice for which corrosion initiation took much longer, even in cases with quite modest
concrete cover and modest concrete quality. Many of these structures show satisfactory long-term structural performance, despite having high levels of localized chloride concentrations at the reinforcement. This disparity was noted already more than 50 years ago, but appears still not fully explained. This paper presents
a systematic overview of cases reported in the engineering and corrosion literature and considers possible
reasons for these differences. Consistent with observations by others, the data show that concretes made
from blast furnace cements have better corrosion durability properties. The data also strongly suggest that
concretes made with limestone or non-reactive dolomite aggregates or sufficiently high levels of other forms
of calcium carbonates have favourable reinforcement corrosion properties. Both corrosion initiation and the
onset of significant damage are delayed. Some possible reasons for this are explored briefly.

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