In current industry, underwater concrete is one of the special type of high performance concrete in which it can perform well at least in strength, workability, service life and probably have a bright future as long as there is a need to construct bridges. With sufficient attention to concrete mix design and placement technique, the underwater concrete casting can be successfully implemented. Thus, this paper investigates the effect of different sodium hydroxide molarity towards the strength of fly ash based geopolymer for underwater concreting.
