MSWI bottom ash as eco-aggregate in cement mortar design

Abstract

The applicability of bottom ash (BA) generated by municipal solid waste incineration (MSWI) as partial replacement of silica aggregate in cement mortar mix design is researched in the paper. In order to evaluate the effect of BA admixture on properties of cement mortar, the reference cement mortar without BA is studied as well. For the applied BA and silica aggregate, grain size curves are measured using standard sieve method. The particle size distribution of both aggregates is studied also by laser diffraction method. 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. For the studied BA, also the powder density in the dry state is measured on gravimetric principle. The influence of BA admixture on mechanical performance of the developed mortars is evaluated by measurement of compressive strength, bending strength and dynamic Young’s modulus that is accessed by ultrasonic pulse method as well as resonance method. Since the durability of building materials is except of the other harmful effects related to the rate of possible moisture transport into their inner structure, moisture diffusivity, sorptivity and water absorption coefficient are analysed using standard sorptivity test. For explanation of the obtained data, the pore size distribution is measured on mercury porosimetry principle. Experimental results proved the applicability of the applied BA as partial silica aggregate replacement in composition of cement mortar, whereas the reuse of studied MSWI residue as mortar aggregate represents an interesting alternative to final landfill disposal.