Can sea sand/salty sand be used for construction?

Justify : Salt free sand should be used for mortar and concrete.

ANS:

            Salts and alkalies play a damaging role in cement setting. Their presence affects the strength of the cement set.

In addition, salts & alkalies have hygroscopic properties. They absorb water from atmosphere and make the walls damp resulting into unhealthy atmosphere and weaker structure.  Also, when the moisture in the wall evaporates, they leave behind white or gray spots spoiling the appearance of the building. This effect is called ‘Efflorescence effect’.

In case a situation warrants one to use sea sand only, it can be used by washing this with pure water till the sand is free from salt.

Hence salt free sand should be used for cement screed, mortar, plaster and concrete.