Fly ashes generated by power and heating plants are commonly used in the production of building materials in some countries, mainly as partial replacement of cement or aggregates in concrete. The ashes from municipal solid waste incinerators can be applied in a similar way. However, their chemical and mineralogical composition, granulometry and toxic constituents have to be taken into account. In this paper, four types of municipal solid waste incinerator (MSWI) ashes produced by the modern MSWI facility in Liberec, Czech Republic, were investigated. The relationship between the particular ash properties (morphology, chemical composition) and its separation temperature in the incinerator line is discussed. A coal fly ash (class F) is characterized as well, for a comparison because its utilization in building industry is more developed. The studied MSWI ashes exhibit high concentration of chlorides and sulfates which is an unfavourable feature for a potential concrete admixture. On the other hand, three of four ashes are found to be pozzolanic active and certain hydration reactions are indicated.
Bottom ash generated by municipal solid waste incinerators (MSWI) is used as partial replacement of silica aggregate in cement mortar. For comparative reasons, also reference cement mortar without ash addition is studied. At first, measurement of particle size distribution of studied bottom ash is done using laser particle size analyser and sieves of specific dimensions. Basic material properties of cement mortar, namely the bulk density, matrix density, and total open porosity, are measured using gravimetric method combined with helium pycnometry. Pore size distribution is determined by mercury porosimetry. Compressive strength and bending strength characterizing mechanical performance of the mortar and moisture diffusivity as a basic indicator of durability are analyzed as well. Experimental results show that the replacement of siliceous sand by bottom ash aggregates in an amount of up to 40% of mass leads to an increase in mechanical properties and slowing-down of water penetration into cement mortar. This is a very prospective outcome for the practical application of the mortar, particularly taking into account that the use of waste bottom ash in building materials production is beneficial from both economical and ecological points of view.
The building industry, especially construction materials' production, is a major user of the world's resources and together with energy production one of the most important sources of the CO 2 production. Among building materials, concrete is element which is the second most consumed substance in the world, whereas only water is used in greater quantities. Apparently, almost one ton of concrete is used for each person in the world each year. From the point of view of ecological and sustainable aspects, concrete industry is now recognized as the largest consumer of natural resources and significant producer of waste. In order to preserve clean environment, there is a need for improvement of existing production technologies of concrete by transforming them into sustainable and environmentally friendly. Municipal solid waste incineration (MSWI) materials as fly ashes and bottom ashes have not dissimilar average chemical composition from that of coal fly ashes and slag from iron production. On that account one can assume possible use of MSWI materials as partial Portland cement replacement in concrete mix design or in a raw state as partial aggregate replacement. Since waste treatment represents serious problem for advanced as well as for developing countries, the use of MSWI materials in concrete production is beneficial for both ecological and financial reasons.Three kinds of MSWI fly ashes in state "as received" were characterized and their potential use as filler in cement based mortars was tested. The motivation of this utilization was to replace part of the fine aggregate dose in the mortars. All tested ashes made the mortars properties worse; the reasons and possible solutions are discussed.
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