ABSTRACT
The effective diffusion coefficient D i is determined
theoretically by applying the simplified NernstEinstein relation (Equation 2).
1 INTRODUCTION
Majority of South African infrastructure is situated in coastal areas exposed to marine environments (Beushausen et al., 2003). Chloride ions from marine exposure act as a critical load on RC structures and as they ingress into the concrete, they increase the potential of the reinforcement for corrosion. Eventually, a chloride threshold level value is attained above which corrosion of reinforcement occurs (Chisolm & Lee, 2001). The period up till corrosion initiation constitutes the service life for concrete structures exposed to chloride ions in most service-life prediction models. Owing to the problems associated with chloride-induced corrosion in RC structures, a reliable prediction method of chloride ingress in concrete is one of the key elements to consider in the design process if the structure is expected to be durable and cost efficient (Luping & Gulikers, 2007). For this study a combination of accelerated testing results and mathematical degradation modelling methods were used for predicting the service life. The degradation model used is based on the concept of chloride transport into concrete by diffusion and initiation of reinforcement corrosion when critical chloride content is exceeded at the steel surface.
