Sulphate Resisting Cement
Sulphate Resisting Cement, as the name indicates these cements are used inorder to resist sulphate action. Ordinary PPC cement is unable to resist sulphate attacks. These cements contain calcium hydroxide and hydrate of calcium aluminium and these reacts with sulphate and form calcium sulphate and calcium aluminate respectively. The byproduct obtained by reactions within the framework of hydrated cement paste results in expansion and subsequently disruption of the set concrete occurs.
The remedy of sulphate attack is sulphate resisting cement. Sulphate resisting cement is a cement with low C3A content and comparatively lower C4AF content. The percentage of C3A (tricalcium aluminate) is kept below 5 percent and it results in the increase in resisting power against sulphate attack.
Sulphate resisting cement is used the following circumstances,
1. Where the structures are subjected to be damaged by severe alkaline conditions.
2. It is widely used in chemical industries.
3. In sewage linings.
4. In Marine Structures,
5. In foundations and basements where soil contains sulphate.