Fundamental Studies on the Utilization of Melting Slag from Incineration Ash from Municipal Solid Waste as Fine Aggregate for Concrete

Abstract

Disposal of incineration ash from municipal solid waste has become one of serious social problems from the standpoint of environmental preservation. In order to cope with this problem, a technique of melting incineration ash at as high temperature as thousand and hundreds degrees, and setting by rapidly cooling using water to produce slag has been developed in recent years. On the other hand, insufficiency of aggregate is serious in the construction industry. As one of countermeasures against environmental preservation and insufficiency of aggregate, this research studied whether or not it is possible to use melting slag from incineration ash from municipal solid waste as fine aggregate for concrete. As a result, the followings have been clarified
1) Slag consists of noncrystal glass, and has no latent hydraulicity. Slag hardly elutes heavy metals.
2) Slag has excellent physical and chemical properties as fine aggregate for concrete though its fineness modulus is high. Since, however, slag has slightly high specific gravity and low coefficient of water absorption, bleeding increases with concrete using slag.
3) Since aluminum particles contained in slag aggregate react with alkali in the cement, the compressive strength of concrete using the slag aggregate lowers with an increase in the amount of mixed slag. For this reason, although slag alone can be used as fine aggregate for concrete of about 20 MPa, it is difficult for high strength concrete of about 30 MPa or more, and means for restraining the expansion is necessary to further improve the quality of slag concrete.