[doodlebug]

Hey Mario, slag like's water when compacted, water causes chemical bonding.
Plate compactor's are just the ticket.
I've hauled a lot, and graded with it, when Geneva Steel was still around, Supply is dwindling here now. No, the slag won't kill weed's! Lime Stone fine's are great too.
Go for at least 2'' thick. 3/8'' minus will compact better than the 3/4'' road base.
Cheer's, Neil.