Simulation of the behavior of pressurized underwater concrete

Under-Water Concrete (UWC) contains Anti-Washout Admixtures (AWA) (0.0%, 0.2%, 0.3%, 0.4% and 0.5%) by weight of cement with cement contents (400, 450, 500 and 550 kg/m3). All concrete mix contains silica fume and high-range water reducing (15% and 4%) respectively by weight of cement. The fine to steel slag coarse aggregate was 1:1. The concrete mix was tested for slump, slump flow, compressive strength and washout resistance using two test methods based on different principles. The first method is the plunge test CRDC61 which is widely used in North America, and the second method is the pressurized air tube which has been manufactured for this research and developed to simulate the effect of water pressure on washout resistance of underwater mix. The results of compressive strength test were compared to concrete cast underwater with that cast in air. Test results indicated that the use of an AWA facilitates the production of UWC mix with the added benefit of lower washout resistance. New technique of simulating pressurized UWC is reliable for detecting UWC properties. Adding AWA (0.3–0.5%) by weight of cement makes all mix acceptable according to Japanese Society of Civil Engineers.