Studies in the system CaSO4+ H2O. Part 6.—Surface chemistry and porosity of the CaSO4 hemihydrates

Abstract

Measurements of surface area and pore size distributions have been used to compare the two forms of calcium sulphate hemihydrate. The α-form, prepared from solution has a low surface area and transitional pores. Dehydration causes a reduction in the volume of the smaller transitional pores and subsequent rehydration causes little change. The β-form has a higher surface area and larger pores. Dehydration increases the volume of the smaller transitional pores and again the effect of rehydration is negligible.