Effect of Seawater on Micro-Nano Air Bubbles Concrete for Repair of Coastal Structures

This paper investigated the effects of seawater curing of concrete made by Micro-Nano Air Bubbles (MNAB) on compressive, flexural and tensile strengths of the concrete. This product will be applicable for rehabilitation or repair of coastal RC structures. In this research, the effect of different combinations of concrete ingredients including 0-100, 25-75, 50-50, 75-25, and 100-0 percent seawater and MNAB, respectively, on compressive strength of concrete was investigated. A total of 93 specimens were experimentally examined to study the compressive, flexural and tensile strength of MNBA concrete (MNABC) through ASTM Standard for cube, cylinder, and beam samples. The samples were cured for 1, 7, 28 and 90 days. Results revealed that MNABC cured in seawater had about 30 % higher compressive strength at ages 7 and 28 days, but it decreased in longer periods. The flexural strength of MNABC slightly increased, about 6%, after 28 days of curing in seawater. In general, the mechanical properties of MNABC at an early age revealed a considerable increase, whereas, in the longer period of time, they were decreased gradually.