Abstract
Man-made deposits of fly ash (FA)—a solid by-product of coal combustion—accompany practically every thermal power station and many industrial plants. The total annual production of FA worldwide is about seven–eight hundred million tons, of which less than one third is recycled. The accumulated FA has become a problem for the environment due to its heavy metal content, which can be leached out. The mineral composition of FA is mainly represented by the glass phase and also by quartz, mullite, magnetite and other minerals. In the last decade, intensive studies have been carried out on the use of FA for the preparation of geopolymer materials. Due to their energy savings, environmentally friendly processing and high physical-mechanical properties, geopolymers are gaining attention in the construction industry as a potential replacement for Portland cement. In this work, we focused on the effect of natural dolomite addition to FA and mechanical activation of this blend on the geopolymerization process. The influence of dolomite dosage and duration of mechanical activation in a planetary mill on the reactivity of the blend in relation to NaOH solution and on the geopolymer compressive strength was studied.
Highlights
We studied the geopolymerization of fly ash (FA) blended with natural calcite [9]
MA of the (FA + dolomite) blends for 30–400 s resulted in a continuous increase in the surface area
It is clear from comparison of the peak intensities that disorder of the mineral lattice and/or decrease of crystallite size induced by milling, for dolomite, were considerably more pronounced than those for mullite and quartz, which are present in the FA
Summary
Geopolymers are a subclass of alkali-activated materials synthesized by the reaction of low-calcium, natural and industrially produced aluminosilicate raw materials, with an alkaline agent (for example, NaOH solution or water glass) at temperatures close to ambient temperature. [1,2,3,4,5] Due to their energy savings, environmentally friendly processing and high physical-mechanical properties, geopolymers are gaining attention in the construction industry as a potential replacement for Portland cement. Geopolymers possess a complex of valuable physicochemical properties, and based on them, it is possible to create environmentally friendly materials for fire and heat protection, wastewater treatment, matrices for the immobilization of heavy metals and radioactive waste, and so on [6,7,8]. We studied the geopolymerization of FA blended with natural calcite [9]
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