EXPANSION INHIBITOR FOR CONCRETE AGGREGATE, AND EXPANSION INHIBITED CONCRETE AGGREGATE

PROBLEM TO BE SOLVED: To provide an expansion inhibitor for concrete aggregate, with which fine metal aluminum particles are made harmless by forming a scarcely soluble protective film on a surface of metal aluminum included in molten slag aggregate, no hydrogen is produced in forming the scarcely soluble protective film, and expansion of concrete can certainly be inhibited inexpensively even when used for example as aggregate in production of concrete for a retaining wall or a U-shaped sewer, and to provide an expansion inhibited concrete aggregate using the same.SOLUTION: The expansion inhibitor for concrete aggregate is an expansion inhibitor used for concrete aggregate composed of metal aluminum containing molten slag aggregate, and includes an acetate of an alkali metal and/or an alkaline earth metal. Potassium or sodium is preferable as the alkali metal, and calcium and/or magnesium are/is preferable as the alkaline earth metal.