Effect of Seawater-Mixed Concrete with Fly Ash on Compressive Strength and Carbonation Depth
Freshwater and ordinary Portland cement is constantly used as concrete material and due to the global warming issue, freshwater usage and carbon dioxide emission from OPC manufacturing must effectively controlled. Seawater which covers more than 70 percent of earth surface has potential to replace the freshwater in concrete. Thus, the main objective of this study is to study the effect of seawater as mixing water and fly as supplementary binder at 20 and 40 percent OPC replacement on compressive strength and carbonation depth. Six series of mix design was designed at target compressive strength of 40MPa at 28 days. All specimens were then immersed in tap water and seawater for 28 days of curing. Compressive strength was tested at 7 and 28 days, while, carbonation test was carried out after 28 days of tap water curing and additional 4 months exposure to indoor and outdoor condition. Results shows that compressive strength was increasing when seawater were used as mixing water and with the increment percentage of fly ash for both type of curing. Meanwhile, the lowest carbonation depth was gained from mixture consist of 20 percent fly ash and seawater as mixing water for both curing type.