Abstract

Fly ash from fluidized bed combustion differs greatly from that of pulverized coal firing. The most noticeable differences are in morphology, reactivity, and chemical composition. The use of biomass fly ash from fluidized bed combustion as a cement replacement material could be a promising method for both minimizing the amount of landfilled fly ash and reducing CO2 emissions in the concrete and cement industry. In this study, fly ash from fluidized bed combustion of peat and forest industry residue was used as a supplementary cementitious material for portland-composite cement (CEM II) containing clinker, blast furnace slag, and limestone. Even with a 40% cement replacement ratio, the compressive strengths of the mortar samples were still as high as 88% of the control sample’s strength. Comparison with unreactive replacement material revealed that moderate hydraulic properties of the studied fly ash explained the positive effects on strength rather than filler or nucleation effects.