The effect of clinker SO₃ on the mineralogical composition of the cement and its expected impact on sulfate resistance level

The aim of this study was to clarify the influence of the SO₃ on the mineralogical composition of low-alkali clinker and to evaluate its expected impact on the cement sulfate resistance level. The influence of the clinker sulfate on amounts of aluminate, alite and alite/belite ratio was investigated. The solubility rate of the clinker anhydrite was studied. The results showed that the clinker phases were affected by the amount of clinker SO₃. The amounts of the aluminate, alite and alite/belite ratio were lower, in the high-SO₃ clinker, than that calculated. Based on these results, cement produced with clinker containing around 2% sulfate and low alkali were expected to have a higher sulfate resistance level than the classical one with similar chemical composition. It was also found that formation of the soluble anhydride was not feasible. The anhydrite that was present in the clinker containing over 2% SO₃, seemed to be dissolved completely within 5 days.