s, P.O

icr atio e in d a ss o ater e ge and strength was found. 2010 Elsevier Ltd. All rights reserved. n as d borated indoo, envi etc. Th on. Tak the hemihydrate. The hydration of hemihydrate such as the hydration kinetics and setting has been studied intensively so far [4–11], but the emphasis was always laid on a-hemihydrate. Therefore topics such as the hydration induced properties, and especially the behavior of the b-hemihydrate upon hydration to produce gypsum (plaster-board) is still poorly understood. This article addresses the proper-perature in order to confirm the mineralogy and crystallinity. The chemical analysis of the material was carried out using energy-dispersive X-ray spectroscopy (EDX). The particle size distribution (PSD) was measured with a Mastersizer 2000. The spe-cific surface area was analyzed from both the measured PSD results and the BET method (TriStar 3000, Micromeritics). The microstructure of the hydrated system was measured with scanning electron microscope (SEM). 2.2. Water demand determination Flowability is widely used to describe the properties of building materials like concrete or gypsum in fresh state and it is related to parameters such as fluidity, mobility, and compactability. To assure the hydrating system is fluid, a thin layer of adsorbed water molecules around the particles and an extra amount water to fil