Strength Development of Seawater Mixed and Cured Concrete with Various Replacement Ratios of Fly Ash

In specific scenario, the only possibly water for mixing and curing water available is seawater. Normally, concrete mixing requires freshwater, a natural resource which is predicted to shortage because of world water paucity. Seawater which envelops more than 70% of earth surface has possibilities to replace the freshwater in concrete mixing. Consequently, it is required to optimize conditions for its implementation in concrete, because freshwater supplies are either restricted or its transport is expensive. Further, the influence of various substitution ratios of fly ash needs further studies to determine applicability on concrete with seawater mixing. Thus, this study aims to examine by which seawater can be employed as water used for mixing concrete, particularly for plain concrete. The main purpose of this study is to investigate the influence of seawater for mixing and fly ash for partial replacement cement at 10%, 20% and 30% for Portland Composite Cement replacement on compressive strength, respectively. The water-to-binder ratio was varied at 40%, 50% and 60%. The specimens were cured (continuous immersion) in freshwater and seawater for 91-days. The results implicated that seawater can be used as mixing and curing water in concrete. Compressive strength of concrete improves when using seawater as mixing water and freshwater as curing water especially for w/b of 40%. Also, significant strength development up to 91-days was shown by fly ash concrete when using seawater as curing water and freshwater as mixing water . Effectiveness of seawater as curing water on strength development of concrete with fly ash for w/b ratio of 40% is larger in concrete with freshwater mixing than seawater mixing.