Solution:For construction of structures in sea water Portland-pozzolana cement are used. This is also known as PPC. Its a integrated cement which is formed by synthesising OPC cement with pozzolanic materials in a certain proportion.Generally it has 15-25% fly ash mixed with the 65-75% portland clinker and 3-6% of gypsum. Pozzolana cement has very good resistance against sulphate attack hence is used in hydraulic structures, marine structures, construction near the sea shore, dam construction etc.