Effect of municipal solid waste incineration fly ash on the properties, microstructure and durability of clay bricks

Abstract

The paper analyses the effect of municipal solid waste incineration fly ash (MWSI FA) on the physical-mechanical characteristics, environmental toxicity, microstructure and durability (freeze - thaw resistance) of clay bricks. The clay bricks were prepared by adding 2.5-7.5 % FA and firing them at a temperature of 1000 °C. The physical and mechanical characteristics of the clay brick change depending on the content of the FA added: the shrinkage, density and compressive strength decreases, while the water absorption and total porosity increases. Also, the mineral composition of the ceramic bodies changed with the FA additions. Clay bricks containing 2.5 % FA do not exceed the limit values of non-hazardous substances according to the Waste Directive 2003/33/EC. The recommended limits of the fly ash addition to the clay brick moulding are 2.5 wt. %. In terms of resistance to freezing and thawing cycles, such products are regarded as freeze-thaw resistant in middle aggressive environments, i.e., in structures protected from direct environmental effects (Class F1 according to the EN 771-1:2011+A1:2015 standard).