STEEL SLAG
Industrial By-product and Construction Material
In the Netherlands, approximately 650,000 tonnes of steel slag are produced each year — the equivalent of around 26,000 truckloads of material. Steel slag is generated during the production of steel and in the Netherlands is primarily produced by Tata Steel in IJmuiden. The stone-like material contains various metals and has been used for decades in roads, embankments, dikes and hydraulic engineering works.
Within Dutch regulations, steel slag is generally not classified as waste, but as a secondary construction material that may be used under certain conditions in roads, embankments and waterworks.
Concerns about the environmental effects of steel slag have existed for some time. Steel slag contains, among other substances, calcium oxide and other reactive minerals. When the material comes into contact with water, chemical reactions can occur in which hydroxides are formed, causing the pH level of soil and surface water to increase significantly, making the water strongly alkaline.
Metals may also be released from the material.
Alkaline water, likely caused by steel-slag leaching, Aagtenpark, Beverwijk.
Steel slag, held by hand. Its alkaline residue can sting and irritate the skin.
Interview
Known steel slag sites in the Netherlands. Squares indicate locations where environmental damage has been reported.
Source: Investico.
Source: Investico.
Research and policy documents indicate that when steel slag is applied in infrastructure or construction, substances may leach into soil and groundwater.
At the beginning of the 2000s, limits for several substances were relaxed in order to allow the reuse of industrial by-products. This was also relevant for steel slag, which contains elements such as vanadium, barium and fluoride.
Through the Temporary Exemption Regulation of the Building Materials Decree (2004), the permitted leaching standards for these substances were temporarily increased by a factor of three, allowing the continued use of materials such as steel slag.
Vanadium, in particular, has been found in elevated concentrations in soil and groundwater at several locations where steel slag has been applied.
In practice, the use of steel slag has led to problems at several sites. On the A28 near Hoogeveen, elevated pH values were measured in soil and water, and damage occurred to the road foundation.
At the Haak om Leeuwarden, steel slag was used as fill material during the construction of the ring road, after which environmental issues were reported.
In Eerbeek and other locations in Gelderland, residents reported complaints such as stinging eyes, nosebleeds and respiratory irritation, which were associated with dust from steel slag and quicklime particles released during transport or processing.
Steel slag is processed and marketed as a construction material by companies such as Pelt & Hooykaas. The material is incorporated into products such as Duomix and Graustabiel, which are used as foundation layers under roads, bicycle paths, parking areas and industrial sites, but also beneath driveways, farmyards and garden paths.
A complete overview of where steel slag has been applied in the Netherlands does not exist. Applications of the material are not centrally registered, which means that in many cases its presence only becomes visible after complaints or environmental investigations.
At the beginning of the 2000s, limits for several substances were relaxed in order to allow the reuse of industrial by-products. This was also relevant for steel slag, which contains elements such as vanadium, barium and fluoride.
Through the Temporary Exemption Regulation of the Building Materials Decree (2004), the permitted leaching standards for these substances were temporarily increased by a factor of three, allowing the continued use of materials such as steel slag.
Vanadium, in particular, has been found in elevated concentrations in soil and groundwater at several locations where steel slag has been applied.
In practice, the use of steel slag has led to problems at several sites. On the A28 near Hoogeveen, elevated pH values were measured in soil and water, and damage occurred to the road foundation.
At the Haak om Leeuwarden, steel slag was used as fill material during the construction of the ring road, after which environmental issues were reported.
In Eerbeek and other locations in Gelderland, residents reported complaints such as stinging eyes, nosebleeds and respiratory irritation, which were associated with dust from steel slag and quicklime particles released during transport or processing.
Steel slag is processed and marketed as a construction material by companies such as Pelt & Hooykaas. The material is incorporated into products such as Duomix and Graustabiel, which are used as foundation layers under roads, bicycle paths, parking areas and industrial sites, but also beneath driveways, farmyards and garden paths.
A complete overview of where steel slag has been applied in the Netherlands does not exist. Applications of the material are not centrally registered, which means that in many cases its presence only becomes visible after complaints or environmental investigations.