PURPOSE: To adhesively place concrete with high adhesive force, without causing dust and noise, and with proper working speed by spraying polymer cement mortar on an exisiting concrete surface for roughening the surface.

CONSTITUTION: The surface of an existing concrete is blown and cleaned with high-pressure water. Next, a mixture of prescribed weight parts of ordinary Portland cement, quartz sand, cellulose, ethylene vinyl acetate copolymer emulsion, and water is sprayed. Then, concrete is newly placed on the sprayed surface. Thus, after the surface has been roughened, by newly placing concrete on it, concrete can be stably placed with high adhesive force.