Biosafety binder based on gypsum-bearing waste

Abstract

Gypsum-based binders and obtained gypsum materials and products are widely used in the world-building materials market. However, not everywhere there is a natural raw material base for their production. In connection with this feature, gypsum-containing wastes from different industries are of particular interest, which can potentially be used as an analogue to natural gypsum stone. One of these alternative options is gypsum-containing waste – citrogypsum. Citrogypsum is a by-product of the biochemical synthesis of citric acid. Based on the fact that 95–97 % of citrogypsum is represented by calcium sulfate dihydrate, it can be considered as an alternative replacement for natural gypsum stone in gypsum binder production. Сitrogypsum is stored in open dumps, contacting with the environment medium. The fungus Aspergillus niger can be found in cytogypsum, which is used as a culture for the microbiological synthesis of molasses in the production of citric acid. Aspergillus niger is a species of higher molds of the genus Aspergillus and can cause disease in humans and animals. In this connection, biotesting of the raw material (citrogypsum) and gypsum binders obtained by sintering citrogypsum using oats (Avena sativa L) and cladocerans (Daphnia magna) was carried out. Gypsum plaster grade G5 was used as control samples. The results of the research allowed concluding that the binder based on citrogypsum meets environmental safety standards. It does not contain a fungus Aspergillus niger that is dangerous to human health. So, it can be used for the production of building products.