Abstract: To improve the durability of fly ash concrete, fly ash concrete was used as the object to analyze the effects of different alkaline activator dosages （0%, 5%, 8%, and 10%） on the quality loss rate, relative dynamic elastic modulus, and compressive strength of fly ash concrete. Microscopic analysis of the alkali excitation process in fly ash concrete was conducted using scanning electron microscopy （SEM） and EDS spectroscopic diffraction patterns. The results showed that with the increase of alkaline activator dosage, the compressive strength of alkali activated fly ash concrete at different curing times showed a trend of first increasing and then decreasing. The quality loss rate of fly ash concrete with four different alkaline activator dosages increased with the increase of freeze-thaw cycles, and the quality loss rate of fly ash concrete was the smallest when the alkaline activator dosage was 8%;the relative dynamic elastic modulus of fly ash concrete with four different alkaline activator dosages decreased with the increase of freeze-thaw cycles, and the decrease in relative dynamic elastic modulus of fly ash concrete was the smallest when the alkaline activator dosage was 8%;the compressive strength of fly ash concrete with four different alkaline activator dosages decreased with the increase of freeze-thaw cycles. When the alkaline activator dosage was 8%, the compressive strength of fly ash concrete was the highest and the decrease in compressive strength was the smallest. The main elements of fly ash concrete with two alkaline activators （0%, 8%） were Ca, O, C, Si, and S. When the dosage of the alkaline activator was 8%, it could effectively promote the hydration reaction of fly ash concrete, increase the hydration product content of cementitious materials, and improve the mechanical and durability properties of fly ash concrete.

Key words: alkaline activator, dosage, fly ash, concrete, durability