In industry, alpha plaster is currently produced by the process of wet dehydration using the pressure method – in autoclaves (a very cost-intensive process). Currently, these are the only bits of equipment used in industry for producing the alpha modification of plaster. Then the product is immediately dried before finally being ground into a fine powder. This is a more expensive and technologically more demanding process than that used to manufacture beta plaster, which is produced by a dry process at higher temperatures without the need for increased pressure.
In the Institute of Building Materials and Components Technology at the Faculty of Civil Engineering, Brno University of Technology, a team of experts working to research and develop new binders has been engaged over the long term in how to prepare alpha plaster by dehydration in a salt solution, i.e. by a non-pressure method. This group of scientists – Ing. Karel Dvořák, Ph.D., Ing. Petr Zlámal, Ph.D., Ing. Karel Kalivoda and Ing. Jan Novák – is led by Prof. Marcela Fridrichová, an experienced expert in the field of inorganic binders and silicate chemistry.
Tests have so far been taken to the pilot-plant stage of production and currently the institute does have functioning laboratory equipment at its disposal, the design of which is legally protected as a Czech utility model.
The newly developed equipment is intended for producing the alpha modification of plaster using a non-pressure method, which means it works on a principle of completely different technology than autoclaves. In the pressure-free types of equipment which are currently used in the production of plaster, only the beta modification of plaster is produced. This does not achieve such high-quality mechanical properties as the alpha modification.
This equipment represents a positive technical contribution, as - without any need for the hydrothermal processing of gypsum and with a relatively simple construction design - it enables the production of very high-quality alpha plaster, i.e. having large, well-developed crystals which possess excellent mechanical properties. Another advantage of the new equipment is that all steps in the preparation of alpha plaster can be realized in one chamber, without the need for any external handling, which would otherwise significantly increase the probability that the resulting product would be inferior in quality.
Currently, the originators of this equipment are working to modify the technology using this non-pressure equipment in order to reduce its operational costs and increase competitiveness – the use of waste materials for preparing the dehydration solution is planned.
