Tetracalcium aluminum monosulfate

For industrial Portland cements, tetracalcium aluminum monosulfate hydrate (C ASH ), which is a major component of fully hydrated hardened cement, reacts with gypsum to form secondary ettringite (C ASjHj ). This reaction also causes expansion of 57 vol.% of the solid components ... 

In the presence of portlandite (CH), the tetracalcium aluminum monosulfate hydrate (C ASHjj) is converted to ettringite when the hydrated cement paste comes into contact with free sulfuric acid from the wet oxidation of sulfides ... 

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