Effect of composition of geopolymer composites containing fly ash and waste glass powder on their durability and resistivity demonstrated in presence of a nanocarbon additive in a form of graphene

•A type of graphene determines a change of physical, chemical and electrical properties in geopolymer composites.•Crystals shape in the mineral composite is affected by a type of nanosilica depending on its hydrophilic or hydrophobic form.•Higher fly ash content in geopolymers increases conductivity.•Presence of glass powder reveals dielectric properties of geopolymer composites.