Electric arc furnace slag (EAF) is a byproduct that outcomes from the 3rd phase of the metallurgical process, fine grained and amorphous due to sudden cooling into water consisted mainly of iron oxide and calcium carbonate. The use of slag aggregates from iron and steel production in construction dates back to the Romans who used crushed slag from the crude iron production of that time to build their roads. Nowadays, slag is still used to build roads. However, slag use is not limited to roads anymore, but slag aggregates are widely used in all kinds of civil works. An aggregate is a granular material used in construction. Properly applied aggregates contribute to the strength and mechanical stability of the construction.