Composition and Structure of Composite Gypsum Binder Stonewith Lime and Hybrid Mineral Additive
The influence of a hybrid mineral additive which includes anthropogenic products - claydite dust and granulated blast-furnace slag in quantities of 20 and 30% of building gypsummass - on the composition, structure and basic physical and mechanical properties of artificial stone on the basis of composite gypsum binder has been investigated. The incorporationof the hybrid mineral additive in combination with additives of lime and superplasticizer into the composition of building gypsum makes it possible to produce the artificial stone withmore dense and fine-grained structure comparing with an initial binder without additives. The appearance of low-basic calcium hydro-silicates which fillthe porous space, compact thestone structure, create additional contacts in the basic matrix, protect splices of gypsum crystals against dissolution is observed. The part of closed pores in the porous structure ofstone on the basis of composite gypsum binder increases. Due to the incorporation of hybrid mineral additive the artificial stone on the basis of composite gypsum binder after 28 daysof hardening under normal conditions has the compression strength of 30.5 Mpa, and softening index of 0.92.