In this study, the effect of the modification level in the flotation method, using LOI as an indicator, on the properties of fly ash and mortar was investigated. As the modification level increased, the BET specific surface area of fly ash decreased, while the specific surface area increased. The particle size distribution also became more concentrated around 10-15 μm. Furthermore, a higher modification level improved mortar flowability, significantly reduced the amount of admixture required to achieve the target air content, and suppressed drying shrinkage. The highest compressive strength was observed at a modification level of Class2 (LOI 2%).
