NEW TECHNOLOGIES BRING IMPROVED PROTECTION FOR LONTILANJOKI BRIDGE
New technological solutions have been utilised to protect the concrete and steel parts of the Lontilanjoki railway bridge in Akaa in Southern Finland. The innovative surface treatment job was completed in compliance with the strict quality, occupational safety, and environmental requirements.
The main contractor for the railway bridge is Finland’s leading infrastructure builder Kreate Oy. According to Kreate Site Manager Antti Kokkonen, co-operation has run smoothly with FSP, who is in charge of the surface treatment. Surface treatment work on the railway bridge was started in June, and despite the demanding working conditions, the project is progressing on schedule and the results have met the expectations. FSP was chosen for the job through a call for tenders.
“Price-quality ratio, strong expertise and previous good experiences flipped the scales for FSP,” Kokkonen describes the early stages of the project.
“We accepted the Lontilanjoki railway bridge challenge with enthusiasm. FSP has a long and well-established history of bridge surface treatment, both in Finland and in the Nordic Countries,” says FSP Project Manager Pasi Kovalainen.
Covers to protect the environment
The surface treatment project was initiated after Midsummer, when FSP started cleaning the badly rusted grids between the steel beams underneath the bridge by sand blasting. Before anything was done, scaffolding were built around the railway bridge and covers put in place to protect the environment.
“It was high time to do surface treatment on the bridge, as it has not been serviced since it was built in 1992. The steel structures of the bridge were in a horrible condition due to waterproofing damages,” explains Kokkonen.
During the project Kreate was in charge of the basic repairs done on the concrete parts and decks of the bridge, including the renewal of water insulation. FSP was charged with the surface treatment of the steel beam structures beneath the bridge. The surface treatment work covered, among other things, repair work that included rounding the corners, washing, shot blasting and a triple-layer coating. The surface was finished with a beautiful bluish-grey paint.
Flexible operating methods
In this project, occupational safety was of vital importance, as the railway bridge was constantly used during the maintenance work. The bridge is located on the route of trains going to Turku and Helsinki, and as many as 150 trains cross the bridge each day. For this reason, each worker completed a railway safety training before the project was started. At most, there were 30 professionals working at the site.
In addition to environmental features and occupational safety, Kokkonen states that it was the security of supply and quality of the work that formed the foundation for the co-operation.
“FSP has given the steel structures surface treatment in a reliable manner, and therefore we have been able to complete the project on schedule. The work progressed smoothly even despite the fact that we were suddenly forced to change the painting system, which resulted in there being more surface treatment work than we had estimated,” explains Kokkonen.
The project was not slowed down even by the rainy July, as the railway bridge was protected with tarpaulins. Six blowers speeded up the drying.
Kokkonen underlines that the surface treatment project included also innovative execution methods. While treating concrete, FSP utilised e.g. impregnating agents and anti-graffiti agents which it has used in bridge surface treatment for a long time.
This approach was based on the fact that concrete is a porous material. For example, water is absorbed into concrete, which causes the surface of the concrete darken substantially. For this reason, the surface treatment work was complemented with impregnating agents that do not significantly change the colour of the concrete in comparison to a dry concrete surface.
The impregnating agents also prevent the water’s capillary transfer through the surface layer, and make the surface of the concrete water-repellent without forming a membrane on the surface.
The purpose of the anti-graffiti agents was to prevent the paints and markers used in doodling from absorbing deep into the concrete, thus limiting the need for cleaning to the surface of the concrete. As a result, the doodles are easily removed from the protective agent.