The contract involved the supply and distribution of bituminous conglomerate for the works of highway construction site in the Province of Brescia.
The public purchaser has authorized the partial replacement of a natural aggregate with an artificial aggregate from the treatment of black steel slags, which properties in terms of toughness and abrasion characteristics are better than natural aggregates.
In this way it was possible to avoid the excessive consumption of natural aggregate by replacing the limestone aggregate in the base layers and binder and porphidic / basaltic layers in the surface layers with artificial aggregates and recovery.
Some basic blends and binder also contained a portion of selected milled.
That decision was made because the cost of recycled asphalts are always lower than tradition asphalt and also because black steel slags have good mechanicas characteristics which improve durability and structural lift.
The use of that mix could be a new solution to improve its recycling and could be also an idea to save money helping the planet.
Asphalt made by black steel slags costs, more or less, 15-20% less than traditional asphalt.
Evidence of success
The results obtained in terms of mechanical performance and durability with the introducing of black steel slags were good.
Also its Los Angeles Test index showed its good characteristics in terms of toughness and abrasion.
Potential for learning or transfer
The most important thing we learnt with this work is how to procude a mix using different materials. Before it we has just done smaller works using this mix, this has been the first big work.
Public authorities could increase the use of recycled aggregate, like black steel slags, in their constructions because that practice could reduce the quantity of that materials in town (we have a great problem in searching new recycling solutions for black steel slags) and also save more money.