The municipality of Avesta in Central Sweden initiated a road refurbishing project and needed to install new refuge islands to make its roads safer for pedestrians to cross. A municipality representative, a local inventor and Outokumpu experts worked closely together to come up with an innovative idea to use a stainless steel frame filled with concrete made of steel slag, a by-product of stainless steel production. A key role in this whole process was played by the local inventor, steel workshop owner Ola Lundqvist, who already had prior experience in using shaped stainless steel frames and concrete.
Safe and sustainable
Combining a stainless steel frame with concrete made of steel slag has numerous advantages. The steel frames were shaped and the concrete poured into the forms in the workshop. The prefabricated elements were then simply lifted into place and bolted to the ground.
As a result, the installation process took hours instead of days. This also improved safety for the infrastructure workers as they were spared the risk of working for days in the middle of busy traffic. “The asphalt on site didn’t have to be torn up at any point, and the refuge island can easily be removed and transferred to other locations,” adds Lundqvist.
The concrete used for the solution was mainly made of steelmaking slag, which greatly reduces the consumption of natural resources. Approximately 80% to 85% of the concrete can be made of the slag; the rest is ordinary cement. Compared to traditional concrete-based solutions, the robust combination is also more resistant to sand and deicing salts used in winter, and to inevitable bumps.
Paving the way for future applications
Outokumpu’s duplex proprietary grade Forta FDX 25 was used to form the steel frame. This grade is particularly soft and flexible to handle and to bend. Less force and fewer tools are needed to work it.
Prefabricated elements combining a stainless steel frame with concrete made of steel slag hold promise not only in road safety, but in many other product groups and industries. Discussions on their further use are well under way.