Influence of the heating process on the use of gypsum wastes in plasters: Mechanical, thermal and environmental analysis

Gypsum is widely used in the construction sector in internal coatings. The fact that the chemical composition of gypsum does not change makes the material fully and eternally recyclable, potentially solving the important problem of the large amounts of gypsum waste that each year go to landfills. Up to now, most of the works that use gypsum wastes subjected the material to a previous heating process. This implies a significant energy consumption, reducing the environmental benefits of the recycling process. This paper shows the second part of a research on which two different types of gypsum waste were used as a substitute of commercial gypsum: gypsum waste from industrial plasterboard production and flue gas desulphurization gypsum from a thermal central plant. In this research, the influence of the heating process on the development of new gypsum plaster composites containing different types and contents of waste was studied. Their mechanical properties and thermal conductivity were determined and a brief environmental analysis, using the Life Cycle Assessment method, was carried out. Based on the findings of this paper, it is confirmed that it is possible to substitute 100% of commercial gypsum with gypsum waste from industrial plasterboard production without any heating treatment, but maintaining a good performance. With this action, apart from the benefits in terms of environmental impacts, a slight improvement in the density, mechanical properties and thermal conductivity of the plaster was obtained. (C) 2019 Elsevier Ltd. All rights reserved.