The invention discloses an anti-
erosion concrete admixture and a preparation method thereof, belonging to the technical field of building materials. The concrete admixture is prepared from 30-50 parts of
fly ash, 10-20 parts of superfine
slag powder, 5-10 parts of a modified expanding agent, 5-10 parts of a water
reducing agent and 3-8 parts of a
grinding aid component. According to the invention,
erosion resistance is realized through two dimensions; firstly, the
fly ash and the superfine
slag powder are added, so formation of
sulfate erosion products is effectively prevented from a chemical level; secondly, fine gaps of a
cement material are fully filled with the expanding agent and other components, so the compactness of the material is increased, and the overall strength of the material is improved; and the superfine
slag powder and the modified expanding agent cooperate with each other, so the
sulfate attack resistance of the material is jointly improved. The additive is low in addition amount; the preparation method is simple; a test piece still meets use requirement after being eroded by high-concentration
sulfate for 120 days; and thus, the additive has wide market prospects.