Influence of waste ashes from biomass combustion on frost resistance of cement mortars

This article presents the influence of ashes generated in the combustion processes of various types of biomasses on the durability (resistance to freezing and thawing after 25 cycles) of cement mortars. Three types of ashes were used for the tests: two fly ashes and one bottom ash. These differ in chemical composition and microstructure in the amounts of 10%, 20%, and 30% of the cement mass and are used as a substitute for standard sand. The ashes are characterized in terms of microstructure and chemical composition. The research shows that, regardless of the type of ash used, all the cement mortars containing ash are characterized by higher durability than the control mortars. Among the modified mortars, the smallest decrease in resistance (by 0.54%) to the process of freezing and thawing is shown by cement mortars containing 10% fly ash from the combustion process of biomass with the addition of sunflower, and the largest (by 7.56%) show mortars containing 30% bottom ash from the combustion of biomass with the addition of sunflower. These findings suggest that the incorporation of biomass ashes, particularly fly ash, into the cement matrix mixes has the potential to improve their durability for road infrastructure applications.