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

Physical and mechanical performance of concrete made with waste rubber aggregate, glass powder and silica sand powder

This study presents experimental results about the effect of incorporating waste rubber aggregates in combination with waste glass powder or silica sand powder obtained from dune natural sand, on the performances of cementitious mixtures. Rubber aggregates (RW) were used to replace crushed sand in concrete mixes with ratios of 10%, 20%, 40% and 60%, while glass powder (GP) and natural sand powder (SP) were used to replace 15% of the cement weight. Nine different forms of concrete with the separate wastes and with the combination of them were designed and prepared. The mixtures were characterized in the fresh and hardened states by means of workability, fresh density, compressive and tensile strengths, propagation of ultrasonic waves and deformability tests. The water/binder ratio and superplasticizer percentage of all mixtures were maintained constant. The results showed that the strength increased with the incorporation of glass powder and rubber aggregates, especially with 10% and 20% RW contents. In addition, the developed rubberized concrete with the incorporation of glass powder presented higher fresh density and deformability, compared to the cementitious rubberized mixtures without GP. Furthermore, the simultaneous incorporation of rubber waste and glass powder enhanced the concretes workability due to the low GP and RW water absorptions.Ministère de l′Enseignement Supérieur et de la Recherche Scientifique, République Algérienne Démocratique et Populaire, Programme National Exceptionnel, Algeria and acknowledge the financial support from the Laboratory of Construction Materials, University of Minho, Portugalinfo:eu-repo/semantics/publishedVersio