Sulphate Resisting Portland Cement (IS: 12330)
Sulphate Resisting Portland Cement (IS: 12330): In this cement the amount of tricalcium aluminate is restricted to on acceptably low value(< 5). It should not be mistaken for super-sulphated cement. It is manufactured by grinding and intimately mixing together calcareous and argillaceous and/ or other silica, alumina and iron oxide bearing materials. The Materials are burnt to clinkering temperature. The resultant clinker is ground to produce the cement. No material is added after burning except gypsum and not more than one per cent of air-entraining agents are added.
Properties: The specific surface of the cement should not be less than 225 m2/kg. The expansion of cement is limited to 10 mm and 0.8 per cent, when tested by Le-chatelier method and autoclave test, respectively. The setting times are same as that for ordinary Portland cement. The compressive strength of the cubes should be as follows.
72 ± 1 hour 10 N/mm2
168 ± 2 hours 16 N/mm2
672 ± 4 hours 33 N/mm2
It should have a fineness of 400 m2/kg. The expansion of cement is limited to 5 mm. The initial setting line of the cement should not be less than 30 mm and the final setting time should not be more than 600 mm.
This cement can be used as an alternative to order Portland cement or Portland pozzolana cement or Portland slag cement under normal conditions. Its use however is restricted where the prevailing temperature is below 40 o C. Use of sulphate resisting cement is particularly beneficial in conditions where the concrete is exposed to the risk of deterioration due to sulphate attack; concrete in contact with soils or ground waters containing excessive sulphate as well as concrete in sea water or exposed directly to sea coast.
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