Structure and Properties of the Gypsum Mortar with Silica Sand Under Temperature Load

The importance of the utilization of gypsum in building increases nowadays because of its very favorable environmental properties. Gypsum mortar has the potential to replace the more commonly used lime or cement-lime mortars, which have a significantly higher environmental impact. Nevertheless, the research of the gypsum behavior and properties was neglected for a long time, and therefore, the information about gypsum is outdated or still missing. Gypsum has excellent fire resistance, but it is necessary to focus on the behavior of the gypsum composites with fillers at high temperatures because of the influence of fillers on the properties and structure of the gypsum composites at high temperatures was not studied sufficiently. This article describes the structure and properties of gypsum mortar with silica sand exposed to high temperatures. The studied composite was exposed to temperatures from 50 °C to 1000 °C. The changes in the microstructure of heated materials were studied by the means of scanning electron microscopy (SEM). The mineral composition, volume changes, and changes in the mechanical properties after exposition to the high temperatures were investigated. It was found that silica sand has a favorable influence on the volume changes. The samples kept their shape even after the heating to the 1000 °C and maintained residual compressive strength of 10.2 %. Graphical Abstract