PURPOSE: To provide an elastic grouting material for repair capable o being grouted into fine cracks of a concrete structure tiled or coated with a mortar and gaps of floated parts in the surface layer within a wide range.

CONSTITUTION: A grouting material for repairing concrete structures is constructed by blending fine powdery blast furnace slag with fine powdery portland cement, a high-performance water-reducing agent and an alkali stimulating agent in an amount of 1.5-4.5wt.% based on the total amount of the aforementioned blast furnace slag and portland cement and a viscosity improving agent in an amount of 0.05-0.2wt.% based on the total amount of the blast furnace stag and the portland cement and mixing the resultant composite material with 40-80wt.% highly elastic polymer dispersion having <0°C glass transition temperature.