SIKA SERVICES AG

The spice of gypsum

Sandra Cunningham

All Sika

With approximately 11 billion m² installed annually, gypsum boards are the most successful gypsum-based construction material [1]. The success of gypsum board is not only due to its excellent physical properties and functional advantages. It is also supported by an efficient, highly automated and continuous production line process which requires high quality raw materials. Besides gypsum binder, water and cardboard, a variety of chemical additives are used during today’s gypsum board production. An overview of the most relevant additives added to the gypsum core is provided based on the literature review and personal experiences. Special attention is given to the topics water reduction and setting time control.

1 Background

Gypsum boards are produced from gypsum plaster, water and additives for the gypsum core as well as cardboard on continuous conveyor lines.

Prior to diving into the chemistry of gypsum additives, a few basic principles of gypsum chemistry have to be recaptured. The chemical reaction of gypsum binder with water is a solution and precipitation process. The crystallization of gypsum follows the law of nucleation and crystal growth. The hydration of calcium sulphate hemihydrate to gypsum can be described with the equation

CaSO₄ 0.5 H₂O + 1.5 H₂O --> CaSO₄ 2 H₂O (1)

Numerous partly desired...

TEXT Dr. Markus Müller, Sika Services AG, Zurich/Switzerland

Issue 3/2020 SIKA AG

Multi-functional polymers for increased gypsum board production efficiency

With the increase of costs, there is a rising need for energy and water reduction in gypsum board production and the use of highly effective water reducing additives are state of the art. Extremely...

Issue 02/2013

Optimisation of plasticizers for gypsum applications

Following their adoption in cementitious systems, superplasticizers based on polycarboxylate ethers are now increasingly being selected for gypsum...

Issue 7-8/2017 Bauhaus-Universität Weimar

Additive-dependent effects on plaster hydration

The purpose of this work was to illuminate the effects of certain additives or of combined additives on a hydrating gypsum plaster. The changes in hydration and the strength development process are...

Issue 07/2024 MATERIALS RESEARCH AND TESTING INSTITUTE (MFPA) WEIMAR

Gypsum plaster made from recycled gypsum

The utilisation of recycled gypsum is becoming even more important with the upcoming loss of FGD gypsum. While RC gypsum (mainly from recycled gypsum plasterboard) is already being used in some cases for plasterboard, its use for other gypsum products is almost unresearched. Research results on a RC gypsum plaster will be presented.

Issue 09/2012