Effect of wet curing duration on long-term performance of concrete in tidal zone of marine environment

A proper initial curing is a very simple and inexpensive alternative to improve concrete cover quality and accordingly extend the service life of reinforced concrete structures exposed to aggressive species. A current study investigates the effect of wet curing duration on chloride penetration in plain and blended cement concretes which subjected to tidal exposure condition in south of Iran for 5 years. The results show that wet curing extension preserves concrete against high rate of chloride penetration at early ages and decreases the difference between initial and long-term diffusion coefficients due to improvement of concrete cover quality. But, as the length of exposure period to marine environment increased the effects of initial wet curing became less pronounced. Furthermore, a relationship is developed between wet curing time and diffusion coefficient at early ages and the effect of curing length on time-to-corrosion initiation of concrete is addressed.Peer reviewedCivil and Environmental Engineerin

Maintenance for Repaired RC Column Exposed to Chloride Attack Based on Probability Distribution of Service Life

Abstract Chloride attack is one of the most critical deterioration due to rapid corrosion initiation and propagation which can cause structural safety problem. Extended service life through repairing is very important for determination of maintenance strategy. Conventionally adopted models for estimation of life cycle cost have shown step-shaped elevation of cost, however the extension of service life is much affected by quality of construction and repairing materials, which means engineering uncertainties in residual service life. In the paper, reinforced concrete column with three different mix proportions exposed to chloride attack are considered, and repairing numbers with related costs are evaluated through probabilistic technique for maintenance. With a given exposure condition, service lives with normal probabilistic distribution are considered, and the effect of design parameters such as coefficient of variation of service life and 1st repairing timing are investigated. The comparison of results from conventional approach (step-function) and probabilistic approach are performed. When calculating repair frequency for intended service life through probabilistic model, the required repair frequency is evaluated to be 6.71 times for OPC, 4.09 times for SG30, and 2.95 times for SG50, respectively. The probabilistic model for repairing cost is evaluated to be effective for reducing the repair frequency reasonably with changing the intended service life and design parameters