Sea water attack

Sea water contain sulphate and hence attack concrete in a manner similar to the sulphate attack.

The deterioration of concrete in sea water is often is not characteristic by the expansion as found in concrete exposed to sulphate attack..attack of sea water causes erosion or loss of constituent of concrete without undue expansion. Calcium hydroxide and calcium sulphate are considerable soluble in sea water, and this will increase the leaching action.

In case of reinforced concrete the absorption of salt result in corrosion of reinforcement. The accumulation of corrosion product on the steel cause rupture of the surrounding concrete. So that affect of sea water is more severe on reinforcement concrete than on plain concrete.

Step to improve durability of concrete in sea water

1) the use of pozzolona or slag cement is advantageous under such condition.

2) Slag, broken,brick bat, soft limestone, or other porous or weak aggregate shall not be used.

3) As far as possible preference shall be given to precast members, plastering should be avoided.

4) Sufficient cover to reinforcement preferable 75mm shall be provided.

5) Care should be taken to protect reinforcement from exposure to saline atmosphere during storage imbrication and use. It may be achieve by treating the surface of reinforced with cement wash or by suitable method.