Partially burnt wood fly ash characterization and its application in low-carbon mortar and concrete

The global shutdown of coal industries has led to a shortage of coal fly ash, a commonly used cement replacement. Wood fly ash (WFA), a byproduct abundant in Canada's timber-based construction industry, emerges as a potential alternative. This study comprehensively characterized a locally available partially-burnt WFA to assess its potential to be incorporated into mortar and concrete. The study was divided into three phases: characterization of the WFA, properties of WFA-based mortar, and concrete. Preliminary findings indicate WFA's similarity to class C fly ash. While WFA adversely impacted mechanical properties, at 15% replacement, mortar and concrete performed similarly to the reference mixtures. The compressive strength of mortar and concrete reduced by 6 and 21%, respectively, slump reduced by 6.7% and chloride resistance in fact improved by 19% at 15% WFA replacement. Considering these results, WFA-based concrete presents a viable option for low-carbon construction.