Effect of Sea Water on Concrete Using Artificial Clamshell Powder and Fly Ash Aggregates

Fly ash is a material suitable for making concrete because of its silica, alumina, and calcium contents, which can improve the compressive strength of concrete. In this study, the researcher tried to renew a mixture that is resistant to corrosion using fly ash and calculating the powder in an oven at 200°C for 60 min to change the nature of the shell powder to become reactive in a concrete mixture. Using experimental methods and supported by previous studies. In this experiment, normal concrete (Fc' = 30 MPa. In this study using 6 formulations, with Fly ash 10%, 10%, 15%, 10%, 5%, and 13% of cement and clamshell power 10%, 20%, 20%, 20%, 20%, and 17%, respectively) from sand. The influence of seawater on salty materials, such as shells, and pozzolanic materials, such as fly ash, during drying affects the compressive strength of concrete. The addition of 20% shellfish powder as a substitute for river sand and a combination of 15% fly ash as a substitute for cement (code. C3-SC) greatly affected the performance of concrete for application in marine areas, with the result that the compressive strength of this composition did not decrease. With a curing experiment using seawater, the compressive strength results at the age of 7 days were 23.93 MPa, at the age of 14 days were 33.55 MPa, and at the age of 28 days were 34.02 MPa. These results indicate that the compressive strength of concrete with this mixture does not decrease. From the research results, it can be concluded that calcined shellfish and fly ash powder materials can be applied to concrete in seawater areas.