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Coal power plants represent the large source of environmental pollution in soils, ground and surface water by leaching out toxic compounds from open landfilled and impounded coal combustion residuals (CCR) such as fly ash. The use of fly ash as a main component in geopolymer binder (GB) systems is one of the effective methods of CCR beneficial utilization. The toxicity assessment as well as leachability of harden geopolymers were tested in aqueous media where oat seeds were used as affected test objects. Bio-resistance of the developed geopolymers was evaluated by the resistance to mold fungi growth. The developed geopolymers demonstrated a very low toxicity and leachability to the biota based on the low effect to germinating ability and growth retardation of the exposed oat seeds. Therefore, the studied fly ash products were proved to be environmentally safe when used in GB systems. The absence of fungi growth observed on the surface of geopolymer samples demonstrates high bio-resistance.

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Class F fly ash is non-demand mineral by-product from fuel industry that is stored in landfills polluting a surrounding territories. Content and composition of soluble mineral components in fly ashes from different power plants are varied in wide range. Leaching into fly ashes these component can differently effect on bioobject activity. In this paper correlation between pH-value of water extracts from fly-ashes, hardness of them and content of evapored mineral residue from the water extract was studied. It is determined the increasing of evapored mineral residue content corresponds to increasing of hardness and pH-value of water extracts.

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