Like the phoenix rising from the ashes, so houses could rise from the ashes of the combusted waste of the Gerbido incinerator.

As the result of a cooperation agreement between TRM, whose members include Iren, the city of Turin, and a number of municipalities in the Turin area, and the Earth Sciences Department of the University of Turin, experimental work is being conducted on the inerting of waste burnt in the incinerator.

Every year, the Gerbido colossus, which went into operation in the spring of 2013, handles 500,000 tonnes of waste, accounting for a significant portion of rubbish produced in Turin and its hinterland. Approximately 80{f94e4705dd4b92c5eea9efac2f517841c0e94ef186bd3a34efec40b3a1787622} leaves the incinerator in the form of fumes. But an additional 20{f94e4705dd4b92c5eea9efac2f517841c0e94ef186bd3a34efec40b3a1787622} – 90,000 tonnes a year – is deposited on the furnace floor, as combustion residue.

Until now, the ashes have been taken to a landfill. Treated like waste, in other words.

«Furnace slag has properties similar to igneous rock such as basalt and granite, and can be used in construction materials,» says TRM president Renato Boero.

Slag recycling is a not insignificant activity in the building sector, which is increasingly attentive to construction process sustainability. Once slag has been treated and rendered inert – which is where the university’s Earth Sciences Department comes in – it could be transformed into secondary raw materials.

The process has at least two benefits: less waste going to landfill, less quarrying of raw materials. The construction market is becoming more aware of the importance of using these “recycled materials”, which also guarantee certification and added value, from an economic viewpoint too. It is no coincidence that they have been employed in the construction of some of the most innovative buildings of recent years, such as the Bosco Verticale residential towers and the Porta Garibaldi high-rise buildings in Milan.