Characterization of coal bio ash from wood pellets and low-alkali coal fly ash and use as partial cement replacement in mortar

Coal is increasingly replaced by biomass at the power plants. This results in new types of fly ashes, e.g. coal bio ash (CBA), where low-alkali coal fly ash (CFA) is injected to the boiler furnace during incineration of wood pellets to hinder corrosion and maintain the necessary thermal efficiency of the fuel. An assessment of the properties of this new type of ash is important for the utilization of this resource. This study reports an investigation of the filler behaviour and pozzolanic activity of CBA, when used as a partial cement replacement. Traditional CFA was used for comparison and CBA was shown to be a more favourable substitute compared to CFA. This study has shown, that by injecting CFA into the boiler furnace, wood fly ash is transformed from being a waste by-product, into a usable resource in concrete production.