Abstract
Mechanical properties and setting behaviour of concrete under water was investigated in this project. Internal curing (IC), self compacting and quick setting are the three most important parameters required for under water concrete. The internal curing & the quick setting properties are achieved by adding sodium silicate to the cement concrete. Self compacting property was achieved by using superplasticizer and to make the concrete not to dissolve in water, sunflower oil was used. Initially to find the optimum usage and the effect of sodium silicate in concrete strength and setting property, the water is replaced by sodium silicate by 0%, 25%, 50%, 75%, and 100%. The compression and split tensile strength was found on the hardened concrete. As a result, the design strength was achieved at 50% replacement of water by sodium silicate. If the sodium silicate was replaced above 50% the strength was decreased. The setting time also decreased with the increase in percentage of sodium silicate. Based on the sodium silicate content, the setting and strength varied. To have under water concrete, the concrete with 75% of sodium silicate by weight of water and 2.5% of superplasticizer by weight of cement along with 2% of sunflower oil by weight of cement was considered. For the control mix, the concrete with no admixtures and additives was taken. The concreting was done under water and the strength properties are investigated for both the control mix and altered concrete. The results obtained are compared and discussed.