Budapest's 97-year-old freight port to be upgraded with heavy-duty trackbed

The Csepel Free Port was opened to traffic in 1928, and its construction was an important breakthrough for the Hungarian economy, which had been isolated after the First World War. In recent years, there have been almost continuous developments at the port: the logistics centre's utilities and road and rail networks have been modernised, and new logistics halls have been built. STRABAG previously built rainwater and sewage drainage systems, as well as fire water and drinking water networks, as part of the port's comprehensive infrastructure development. This time, they are working on the construction of a heavy-duty track surface in the container terminal area.

So far, 18 thousand square metres of concreting have been completed

The STRABAG specialists took over the worksite in October 2023 to construct around 30,000 square metres of heavy-duty surfaces for receiving transport vehicles - trucks, trains - and for loading and storing containers. The first phase of the works involved the construction of 17,617m2 of surfaces. In the second phase, 8,653m2 and in the third phase, a further 3,542m2 are still to be concreted.

For subsoil replacement and stabilisation

The main load on the new roadbed was provided by the 45 tonne loaders. The rigid basalt concrete can only support the load without damage if the layers are properly arranged. This requires extremely careful preparation of both the subsoil and the protective layer.
The minimum load-bearing capacity of the subsoil is defined as E2=50 N/mm2. To ensure this, a soil replacement or cementitious soil stabilisation was required.
Then the specialists constructed the bedding or protective layer. The purpose of this was, among other things, to distribute the load on the rigid concrete surface.

The bedliner layer helps to distribute the uneven load

The bedding layer is more elastic than concrete and can deform to a lesser extent, thus absorbing and distributing uneven loads on the concrete. Its function is to dampen vibrations and shocks due to loading, thereby reducing stresses in the concrete structure, which ensures a longer service life.

Under the 20 cm thick Ckt-4 base course, also 20 cm thick, a frost-resistant, granular protective layer was built using a specified quality of crushed basalt stone, Z 0/45 mm. The base course was specified to have a minimum load bearing capacity of 80 N/mm2 at 96% density. It should be noted that the bedding also serves as a frost protection layer.

Expansion gaps control thermal expansion

After receiving the substructure and Ckt-4 cement stabilization base course prepared and qualified by our Client, a bitumen emulsion or PE film separation layer was formed to help the layers move separately. It also has the additional function of aiding the water retention of the concrete pavement.
In the case of a large continuous concrete surface, the problem of thermal expansion is solved by so-called expansion joints.
The concrete pavement on both sides of the gap is separated by a 2cm thick flexible expansion joint insert over the full thickness and along the entire length of the gap.

Concrete finisher also helps the work on the vast site

Concreting is done by hand and using a concrete finisher. The machine needs a minimum starting lane length until the paving parameters are set correctly and the same applies to the finishing of the lanes. The latter works in 5×4 m lanes. Due to the size of the concrete finisher and the sliding shutter fitted, the exit from the lanes requires a considerable area - at least 15 metres.

However, the surface is completely continuous, so hot-pourable or cold-applied materials that adhere well to the concrete are used to seal the gaps.
Dilatation joints are cut to the pouring size -10*35mm - and then the joints are filleted, this is a 45° chamfer. After insertion of the bottom filler material and floating, a hot workable modified bitumen pour is applied. This represents approximately 14700 metres for the whole project.

Surface roughening to ensure proper adhesion

Drainage on the surface is only achieved by the design of the appropriate slope. In addition to the concreting of the vast area, it is a major technical challenge for the contractors to connect the existing surfaces to the existing ones due to the varying heights.

Concrete is delivered to the site from a mixing plant, and so far 10 770 cubic metres have been delivered and placed.

Surface roughening is part of the technology, but its design is key to subsequent operation. A fine surface does not provide sufficient traction for vehicles on the road, while a surface that is too rough can lead to increased wear on tyres. Post surface treatment can be used for target machines, but this is only economical for very large surfaces (e.g. airport runways). Adequate roughness can be developed by so-called sweeping. After proper curing of the fresh concrete surface, it can be achieved by forming strips perpendicular to the direction of paving.
The project will be carried out by the experts of STRABAG as subcontractor of Mészáros és Mészáros Zrt. on behalf of Mahart-Szabadkikötő Zrt..
A total of 29,812 square meters of surface area will be constructed or
renovated in the container terminal area.