Steelmaking slag set for role in roads

A project is underway that will investigate the re-use of steelmaking slag as an aggregate for roads

steelmaking slag
Steelmaking slag could be incorporated into roads

The UK steel industry generates thousands of tonnes of coarse steelmaking slag per year, which could be used a high-grade road surfacing material.


To this end, the Materials Processing Institute (MPI), along with industry and research partners, has secured a grant worth £118,363 to look at turning the waste product into a viable aggregate. The research is supported by Innovate UK as part of the Transforming Foundation Industries initiative.

Chris McDonald, chief executive of the Institute, said: “We are delighted to have been awarded the funds for this innovative project that will seek to repurpose materials that are either already destined for landfill or difficult to reuse.”

According to the Institute, steelmaking slag is already crushed and used in the road construction process, but its currently approved 60 PSV (Polished Stone Value) level of skid resistance limits use on UK roads.

The 12-month project – which includes Tarmac, British Steel, Glass Futures Ltd and PWS road building services – will seek to increase the silica content of the slag, a by-product of basic oxygen steelmaking (BOS), to improve its quality and consistency and achieve a higher PSV classification.

The Institute said it will investigate using slags produced in other areas of the steelmaking process, including desulphurisation slag, which is difficult to dispose of, and conduct research into the waste streams produced by the glass industry that cannot be recycled.

Its objective is to create several new slags modified by high silica sources, which will be tested by Tarmac for skid resistance. The most promising will be produced in a full-scale plant trial before undergoing further testing.

The project will also undertake a detailed assessment of the volumes and values of waste – or difficult-to-reuse – streams of appropriate material from the glass and steel industries to determine the potential for use as a slag modifier.

“The UK steel industry produces around 550,000 tonnes of coarse steelmaking slag annually. A commercially viable material will reduce waste, contribute to the circular economy and increase the competitiveness of the steelmaker, glass producer and material processor,” said McDonald.