UNIVERSITY OF SIEGEN

Investigations of the hydration of calcium sulfate hemihydrate

The application of calcium sulphate based binders need different properties, which are influenced by the morphology of the dihydrate crystals, and which depend on applied additives, reaction temperature or the production conditions of the reactant hemihydrate. The results show first only hemihydrate which is dissolved and the retarding period starts. Seed crystals of dihydrate are formed subsequently during the next few minutes.

1 Introduction

Gypsum is one of the most used materials in the world; 119 million tons of natural gypsum were extracted worldwide in 2006 (MINERAL COMMODITY 2007). Additionally another 200 million tons of byproduct gypsum came from different processes like phosphoric acid, citric acid or hydrogen fluorine production or from flue gas desulfurization.

Calcium sulphate based binders and gypsum are used for very different technical applications like floor pavement, stucco or plaster board in the building industry, for casting in the ceramic industry, as an additive in polymers or in colors or for...

Related articles:

Issue 2020-10 UNIVERSITY OF SIEGEN

Investigation of hydration mechanisms of alpha and beta hemihydrate

1 Introduction Calcium sulfate hemihydrate [CaCO4???0.5H2O(s)] can be found naturally in very dry climate regions in Egypt, Australia, Death valley and Kuwait as bassanite, but in the presence of...

more
Issue 2009-03 Materials Science

Acceleration of the setting of hemihydrate plaster with calcium sulfate dihydrate

1 Introduction Calcium sulfate binders are required to have widely varying properties to meet technical and economic requirements. In particular, it has to be possible to vary the workability time and...

more
Issue 2017-11 URAL-OMEGA, PJSC

Aspects of gypsum dihydrate crystallization in the artificial aging of gypsum binder

1 Introduction The search for effective technological operations to stabilize technical characteristics used in producing gypsum binders has received a great deal of attention in recent years owing to...

more
Issue 2013-02

Superplasticizers in the calcium sulfate system – plasticizing action and influence on hydration

1 Introduction The use of superplasticizers to optimize the consistency and the amount of water required is now indispensable for numerous practical applications in the field of calcium sulfate...

more
Issue 2010-11

Progress of hydration and the structural development of hemihydrate plaster

1 Hydration and hardening of gypsum-based plasters The hardening of gypsum building materials is based on the crystallization of calcium sulfate dihydrate from a solution that is supersaturated with...

more