Reliability approach to service life prediction of concrete exposed to marine environments

During their lifetimes, structures are subjected to external actions or agents that in time may alter them from a safe state to failure or a damaged state. One of the processes that may trigger the onset of corrosion of steel embedded in concrete is the ingress of chloride ions that eventually reach the reinforcement, causing the rupture of the passive film. In this paper, a method is proposed for interpretation of immersion test results and prediction of the service life of concrete structures exposed to chloride ions. Once the chloride profiles are determined after the immersion test, a realization of the random diffusion coefficient is obtained at each point for which there is a measurement of the chloride content. These samples are used to estimate the probability density function of the diffusion coefficient. A reliability analysis is subsequently performed for 10 different lightweight high-strength concrete mixes. A reinforced concrete element is considered to have failed when corrosion initiates at the reinforcement, i.e., after a certain chloride concentration threshold is reached at the reinforcement. The probability of corrosion initiation in time is calculated for some of the concrete mixes investigated.