When Vejdirektoratet (The Danish Road Directorate, ed) builds the new charging stations and truck parking spaces at the rest areas at Tappernøje in South Zealand, they will use slag gravel as a trial to replace the natural sand and gravel layers under the asphalt. Slag gravel is a residual product from waste incineration, where the municipalities’ residual waste comes back as a raw material for the construction of roads and paths. This is written by Vejdirektoratet in a press release.
Should ease the pressure on gravel pits
The experiment is going to ease the pressure on the gravel pits in Zealand so that natural raw materials are saved, and in this way, Vejdirektoratet is pulling construction in a greener and more sustainable direction.
– At Vejdirektoratet, we focus on using sustainable materials and finding alternatives to natural raw materials. Especially in areas where resources are scarce. Slag gravel is a residual product that is approved for road construction, and as part of the trial, we will keep an eye on how the material behaves and lasts over time. Our hope is that the material will contribute to us being able to save on natural raw materials in the projects where it makes sense, says project manager at Vejdirektoratet, Charlotte Veiss-Pedersen, in the press release.
Saves 100 tons of CO2
Vejdirektoratet has received environmental approval for the use of slag gravel, which under the right conditions will not have a negative impact on the surrounding nature. Vejdirektoratet expects that the use of slag rather than natural raw materials will result in a saving of around 130.000 euros and 100 tonnes of CO2 when rebuilding the two rest areas.
Can replace natural raw materials
It is the municipally owned company Afatek that processes the certified slag gravel. Vejdirektoratet is positive about using the material on projects where it can replace the natural raw materials, which in the long term are expected to be in short supply in many parts of the country.
New road ruleset on the way
It has long been possible to use incineration slag as bottom protection or filling in, for example, dams. Vejdirektoratet is now in the process of drafting a new road rule, which means that incineration slag can also be used in the base layer itself just below the asphalt. Preliminary results show that incineration slag as a base layer is in terms of quality at the same level as traditional stable gravel.
Secured against seepage
When incineration slag is used for the construction of roads or cycle paths, the slag is encapsulated to ensure against seepage of rainwater into the groundwater. This is done by establishing a dense coating of asphalt over the slag or laying out a membrane before putting soil or grass on top of the material.
Slag from incinerators
Afatek gets its slag gravel from six different incinerators in Zealand and subsequently extracts metals from the slag. In this way, they ensure slag gravel with properties that match the traditional road-building materials.
