Behaviour of low heat sulphate resistant cement in aggressive media

Abstract

The low heat sulphate resistant (LHSR) cement has been produced by activation of granulated blast furnace slag with low temperature phase of gypsum, i.e .calcium sulphate hemihydrate (CaSO₄.1/2 H₂O) produced at 150^oC. The LHSR cement was tested and evaluated as per IS: 4031 - 1995 and the properties compared with ordinary portland cement (OPC). The LHSR cement on hydration produce ettringite, C-S-H and C₄AH₁₃ as the major hydraulic products. The suitability of LHSR cement was examined for its use in sulphate solutions such as Na₂SO₄.10H₂O, (NH₄)₂SO₄, MgSO₄ and in mixture of NaCl and Na₂SO₄.10H₂O. Data up to 90 days of curing in sulphate solution is reported. The results show that with curing, a fall in compressive strength of LHSR cement as well as OPC took place. However, the fall of strength was lower in LHSR cement than the OPC. The attainement of higher strength values in LHSR cement in sulphate solutions may be correlated with the formation of increased quantity of C-S-H and decrease in Ca(OH)₂ and ettringite. The LHSR cement may be used in construction work to obviate sulphate attack.