Utilization of blast furnace flue dust while modifying gypsum binders with carbon nanostructures

Abstract

For improvement of physico-mechanical properties of plaster materials the industrial waste - metallurgical dust formed by manufacture of steel, was used. Modification of gypsum binder by adding metallurgical dust in quantity 0.5% from the weight the binder caused the significant change in microstructure of the gypsum stone, this led to an increase in compressive strength by 80% and to increase of softening coefficient up to 0.85. Such parameters are provided due to formation of crystals of the gypsum protected by an environment of amorphous structure, less soluble, than the not protected crystals of gypsum, preventing destruction crystals of gypsum and water limiting access to crystals of gypsum matrix. For achievement synergetic effect with metallurgical dust dispersions multi walled carbon nanotubes (MWCNTs) were added. MWCNTs act as the centers of crystallization on which surface is going the formation of the ordered dense structure to block packing crystals. The presence in metallurgical dust calcium hydroxide leads to formation of amorphous phase on surface of crystals of gypsum. The developed plaster composition modified by the combined additive according to its properties is similar to waterproof materials. Recycling of metallurgical dust using it as the additive modifying gypsum binder, will improve the ecological conditions in area of an arrangement of the steel production metallurgical complexes.