Leca LWA has been used in the geotechnical solution for Odense Light Rail, which is expected to start running in 2021. The light rail will be running on Funen from Tarup via Odense Railway Station, University of Southern Denmark to the new super hospital to Hjallese. The contract was carried out in a consortium consisting of Comsa, the Munck Group and Efacec. The consortium chose to carry out the task as a traditional roadstructure with the establishment of drainage and draft pipes, as well as the incorporation of support layers in which Leca LWA was applied on a stretch of soft ground. Everything is now awaiting to be completed with the installation of a concrete layer in spring, after which electricity will be drawn and rail lines will be laid out by a rail contractor.
Munck is in charge of the construction of the light rail on a large part of the route, and they have been working on the project since 2018. Leca LWA became part of the project when they encountered soft ground on a stretch across an old swamp near Odense Stadium - Nature Energy Park in 2019.
Thomas Damborg from Munck, who was the project manager of the section where Leca LWA has been used, says: “The consortium's advisers had prescribed that lightweight aggregates should be used in the section as there were challenging soil conditions. It was Chairman Martin Debel and I who contacted LECA and together with Knud and René found a solution”.
Knud Mortensen, technical advisor at LECA, and René Jespersen, Sales & Marketing Director, were able to draw on experience from similar constructions both at home and abroad.
The final solution was to use a Triax 170 reinforcement net between two 25 cm layers of small stones, followed by a 70 cm layer of Leca LWA wrapped in a nonwoven cloth/fiber cloth.
On top of the Leca layer, there is a layer of sand, and finally a layer of concrete will be cast in spring, on which the rails will be laid. Easy delivery with blowing vehicles 4,200 m3 of Leca LWA was used in the project and they were delivered with blowing vehicles. There were 3 men attached to each blowing vehicle - one to hold the hose, one to help move the hose and one to distribute the pellets. When the material was distributed, the thickness of the layer was measured to check how much it would settle after compression. It had to reach a maximum of 8-12 %, and
this requirement turned out to be fulfilled.
Martin Debel says: “Working with Leca LWA has been a great experience. I am surprised at how compressible it is - despite the fact that it is round pellets, it stands firm. Also I'm impressed that such a hardness can be achieved on the surface of such a lightweight material. "
It's all about compensating the ground for the weight of the heavy construction, and Leca LWA has been the solution for that.
The most resource efficient solution “At approx. 14 meters down to solid ground, it was not a possibility to remove the soft soil. Piling had been an alternative solution, but it often causes shaking and noise pollution. Pre-loading with sand was also not an option as it takes a long time for the soil to settle – time that we didn’t have. Leca LWA used as load compensation was the most resource-efficient solution for this project”, Thomas Damborg says.
Thomas was familiar with the material, having previously worked on projects in Sweden, where load compensation with Leca LWA had been used under roads. He could easily imagine using Leca LWA for future geotechnical solutions and says that he has been very pleased withthe collaboration