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

Expected life of silane water repellent treatments on bridge decks phase 2 / M. Tyler Ley, Mehdi Khanzadeh Moradllo.

This report outlines the investigation of the service life of silane sealers on Oklahoma bridge decks as well as laboratory investigation of a silane sealer and a two part sealer that uses both silane and epoxy. The performance of silanes on bridge decks was completed on 60 bridges that were in service between 5 to 20 years. Samples were taken from the travel lane and the shoulder. The work found that after 12 years that 100% of the silane applications were effective. By 15 years then only 68% were still effective and between 17 to 20 years then only 16% were still effective. The investigations suggest that abrasion was not a major deterioration mechanism; instead, deterioration from the high alkaline pore solution is suggested to be of importance. This work goes on to investigate a two part system of silane and epoxy sealer, a silane, and then a control sample and their resistance to chloride penetration. Both sealers show improved performance over the sample with just concrete. Additionally, a new experimental technique is presented that is capable of non-destructively imaging the penetration of external fluids into paste and mortar. This test is rapid, accurate, and can be used for in-situ testing. This test method again shows that the silane investigated was effective at reducing the ingress of ions.Final report, October 2013 _ September 2015N