Influence of various replacement ratios of fly ash to concrete mixed with seawater

To minimize the problem in the unequal distribution of the country\u27s water supply, the use of seawater as an alternative for fresh water in concrete was utilized. However, the problem is that the high concentration of chloride present in the seawater penetrates the reinforced concrete making the steel reinforcements corrode. Therefore, the use of fly ash would help delay the effects of chlorides on the reinforcement steel, and help minimize its problem in disposal. The main objective of the study was to determine the influence of various replacement ratios of fly ash to concrete mixed with seawater. The study of the influence of various replacement ratios of fly ash to concrete mixed with seawater was composed of two phases. First was the influence of the material in terms of the compressive strength of the modified concrete mix, and the influence of fly ash on the corrosion of the reinforcing bars in concrete mixed with seawater. Concrete specimens with 0%, 10%, 15%, 20%, 30%, 40%, and 50% fly ash replacement ratios and Ordinary Portland Cement mixed with fresh water and seawater were prepared. These specimens were cured in freshwater and seawater. The compressive strength of the specimens were tested on the 7th, 14th, 21st, 28th, 56th, and 84th day. For the corrosion test, the corrosion potential, corrosion current densities, corrosion rates, and the chloride contents were also determined. The results showed that the 15% fly ash replacement showed the highest compressive strength at the 28th day. The optimum fly ash content for the compressive strength ranges 20% to 25%. Meanwhile, 10% to 20% fly ash replacement range in general showed a significant improvement in the corrosion of specimens compared to those with no fly ash content. However, for the specimens mixed with seawater but cured in fresh water, a 50 % fly ash replacement ratio in the best amount to add in the mix to show a significant decrease in its corrosion rate