An Experimental Study on Effect of Seawater on Strength of M30 Grade Concrete

Abstract

The concrete structures constructed near the coastal areas may deteriorate due to the action of sea salts present in seawater on hardened concrete surface with passage of time. The strength decreases due to the formation of complex ions when chloride and sulphate ions, react with cement hydration products. In this study, experiments were carried out to get the effect of seawater on the strength of M30 grade concrete in laboratory to measure compressive, split tensile and flexural strength. 15 sets of cube of size 150×150×150 mm, 15 sets of cylinder of diameter 100 mm and height 200 mm and 15 sets of beam of size 100×100×500 mm were cast. Out of these 15 sets of each specimen, five sets were kept in plain water, five sets in artificial seawater of 1N concentration and five sets in artificial seawater of 8N concentration. 1N seawater means normal seawater made by mixing tap water with exact amount and proportion of principal salts found in natural seawater. Each specimen was tested after an interval of 30, 60, 90, 120 and 180 days. A comparison was made between the strength variation of concrete in 1N and 8N concentration of seawater and plain water.

Keywords:Seawater, concrete, compressive strength, split tensile strength, flexural strength