PURPOSE: To effectively bury and repair cavities in a waterway, by charging a spherical or polyhedral coagulated adhesion material which is composed of ceramic cubes mixed with cement and an admixture and stuck thereto, into the cavities of waterway.

CONSTITUTION: Ceramic balls 2 having 0.6 or lower specific gravity and 3-50 mm diameter are formed by use of aquaballs or crushed granules of building materials coated with ceramics on the surfaces thereof, slugs coated with ceramics at the surface thereof, etc. And the ceramic balls 2 are mixed with cement 3, an admixture chiefly made of calcium or iron oxides, and water and the products are divided into spherical or polygonal lumps having appropriate sizes and dried to form coagulated adhesion materials 1 having a specific gravety lower than 1.0. The coagulated adhesion materials are charged in a reinforcing material constructed on a mountain slope, a retaining wall of a dam reservoir, or in the inside of waterway cavities formed on the connection face between a tunnel and soil.