This Standard specifies the melt-solidified slag material (hereafter referred to as molten slag) to be used for general road construction materials such as aggregate for asphalt mixture, roadbed material, and banking material.

The molten slag covered by this Standard is a slag material manufactured for the purpose of efficient utilization of the municipal solid waste, sewage sludge, etc. in the melt-solidifying facilities, and includes the following. Molten slag is synonymous with melt-solidified material.

• The molten slag produced in private melt-solidifying facilities which are entrusted by the municipal authorities to treat the municipal solid waste, or that produced when municipal solid waste is treated together with industrial waste whose reuse is approved by the municipal authorities.
• The molten slag subjected to treatment such as magnetic selection, particle size adjustment, etc. or property modification in the melt-solidifying facilities or separate facilities.

Molten slags are classified into granulated slag, air-cooled slag and slow-cooled slag. In this Standard, the term "slow-cooled slag" refers to both the air-cooled slag and slow-cooled slag.