For the first time in Lithuania, slag was used in road construction


Works of construction of a unique road section, where slag generated in the process of conversion of non-hazardous waste to energy was used, were recently completed in Jurbarkas district. This is the first project of such kind in Lithuania aimed at studying the road in detail and determining the impact that slag has on road operation. The conducted study and the evaluation of the achieved results will allow to decide on further use of slag on Lithuanian roads.

9 000 tons of slag which was generated at the UAB Gren Klaipėda waste-to-energy plant and prepared for use was used in the one-kilometre-long test section. The client of the project was SE Lithuanian Road Administration, the contractor – AB Kauno Tiltai, while the Vilnius Gediminas Technical University (VILNIUS TECH) conducted research in the course of road installation and operation.

The exact location of the experimental section is the regional road of national significance No. 1705 Mikutaičiai I–Vertimai, from 1,8 to 2,8 km, in Jurbarkas district. 5 experimental paving structures were installed in this section. The project has been implemented in two stages. The first stage is the installation of an experimental section and the second stage will be the assessment of the possibility of using slag on the road with the help of installed sensors. The second phase will last till April 2024, but performance results are likely to be available after the first or the second winter.

“The first attempt in Lithuania to use slag generated during the incineration of non-hazardous waste in the construction of roads is an excellent example of the implementation of principles of circular economy. If this experiment proves successful, we would reap comprehensive benefits – waste amounts would be reduced, leaving the environment cleaner, and we would have recycled raw materials generated in Lithuania for expanding road infrastructure. This would be a new step in the transport sector, opening up wider perspectives for the use of environmentally sustainable materials in road construction”, the Minister of Transport Marius Skuodis said.

In September, the Ministry of the Environment approved new requirements for the treatment of ash and slag, which allow using slag remaining after waste incineration in road construction, installation of building foundations, covering layers of disposed waste, closing landfills and installation of temporary roads in them.

The Minister of the Environment Simonas Gentvilas hopes that if the experiment proves successful, it will become possible in the future to use all the secondary raw materials generated in the country, including ash and slag, which will replace granite, which usually is imported into the country. “I invite drivers going through Vertimai village to take note of the road section, which professionals have turned into a road using material that was once our waste. The use of ash and slag creates new value instead of disposing of useful materials in landfills,” says the Minister of the Environment.

Remigijus Lipkevičius, Director of SE Lithuanian Road Administration, says that having obtained positive research results and determined that proper use of slag generated in waste incineration plants in Lithuania is possible, volumes of disposed slag and its disposal costs could decrease, also leading to a decreased need for new aggregates (gravel, crushed stone) extracted in quarries.

According to Vitalijus Žuta, General Director of UAB Gren Lietuva, this is another long-awaited stage of waste utilization. “Since the time when the first waste-to-energy plant started operating in Klaipėda, we have been actively and consistently working to ensure that slag is recognized a useful material, and would be put in use rather than simply disposing of it. During that time, we conducted five long-term studies with various departments of Vilnius Gediminas Technical University and proved that our slag is a reliable and useful material. And this project brought this idea to life,” said Vitalijus Žuta.

There are currently three waste-to-energy plants operating in Lithuania with a total capacity of 615 000 tons of waste per year. In the process of energy recovery, i.e. incineration, about 20% of this amount comes up in the form of slag. Thus, about 120 000 tons of slag are generated in Lithuania per year. Slag forms in the process of incineration of non-hazardous waste at temperatures as high as 1000°C and is a solid, cellular material.