slag cargo?

[Guest]

It is also used for seal coat cover, aggregate base course for paving, septic drain fields and railroad ballast.

[vm]

Slag is used in the production of concrete.

[glen]

i've seen references to slag as a cargo which leads me to this. what is useful for? it has to have some value in order to be shipped. as a kid i remember seeing coal ashes used on roads in the winter but never thought about slag.