Gypsum: an investigation of microstructure and mechanical properties

This article addresses the microstructure and mechanical properties of a ß-hemihydrate produced gypsum from a combined study of hydration and dehydration. A thin layer of adsorbed water molecules around the particles is necessary to assure the fluidity of the hydrating system and the thickness of this water layer is derived using the spread-flow test. The shape factor of the investigated hemihydrate is derived from the spread-flow test. The mechanical property of the generated gypsum is investigated and the influence of water content is discussed. The dehydration of gypsum is studied by both thermo gravimetric analysis and heating the samples in a ventilated oven. A model is proposed to describe the microstructure change beyond dehydration and experimental results show its validity. The mechanical property of the gypsum beyond dehydration is presented as well.