Foam concrete is a material that is still not widely used in our country, despite outperforming conventional technologies in many respects. However, in recent years, its popularity has been growing in certain areas of construction, one of which is the use of foam concrete in bridge construction.
Foam concrete has been known since 1923 and has been widely used in various areas of construction. In Poland, this material is still paving its way with some difficulty, and investors typically choose it when conventional solutions cannot be implemented. This is unfortunate because successful projects demonstrate that foam concrete not only has excellent technical parameters but also allows for reducing the cost of investment. This applies to both the use of foam concrete in bridge construction and filling voids in transportation construction and road construction or renovation.
Foam Concrete for Bridge Construction
Each year, more bridge structures in our country are being built using foam concrete, thanks to developments in chemistry, technology, and machinery construction. Foam concrete is beneficial for bridge construction and access zones for several reasons, primarily due to its lightweight nature, which acts as both a filler and a load reducer for abutments.
As a producer of foam concrete, we have contributed significantly to popularizing this material. Among our projects are:
- Viaduct in Wolsztyn on the Poznań-Zielona Góra Route
Foam concrete was used to fill the abutment of the road viaduct in Wolsztyn on the Poznań-Zielona Góra route. This project required reinforcing the abutment structure, which was damaged due to the subsidence of the viaduct’s abutment. It was also necessary to reduce the load on the structure in this critical area to prevent further damage. The foam concrete used in this project had a density three times less than that of traditional fill, which was sufficient to bind and stiffen the abutment.
Filling the abutment with foam concrete.
- Foam Concrete in the Construction of the Bridge over the Vistula River on the A1 Motorway near Toruń
As a foam concrete producer, we also supplied material for the construction of the bridge over the Vistula River on the A1 motorway (near Toruń). The foam concrete slab with a density of 1000 kg/m3 provided good load-bearing parameters under one of the bridge supports.
Using foam concrete in the bridge support.
- Railway Viaduct in Gorzów Wielkopolski
Another example of bridge construction where foam concrete proved effective is the over 150-year-old railway viaduct in Gorzów Wielkopolski. A thorough renovation was carried out, reinforcing the old brick structure with new reinforced concrete spans. The space between the spans and the track was filled with foam concrete with a density of 1300 kg/m3. Over 5000 m3 of foam concrete was used in this project.
Using foam concrete above the brick-concrete spans.
The above examples of using foam concrete in bridge construction demonstrate that this material can be used even in difficult and demanding projects. What specific parameters make it so effective where traditional technologies fail?
Properties of Foam Concrete
Foam concrete is classified as lightweight concrete, with a pore content of not less than 20%. The range within which its parameters can be shaped is very wide, including both density and physical properties.
For building contractors (including those for bridges), foam concrete is easy to produce and incorporate (applied in liquid form), which is a significant advantage. Additionally, it allows for reducing the overall investment cost by about 30% (compared to conventional solutions) due to its low production and installation cost. Using foam concrete eliminates the need for deep earthworks, which avoids the use of specialized heavy construction equipment.
Foam concrete is also self-compacting, so there is no need for vibrators or vibrating beams. This also reduces the number of people needed to carry out the work.
When using foam concrete for bridge construction, its frost resistance, thermal insulation, and ability to dampen vibrations and shocks are also important.
Furthermore, foam concrete aligns well with the principles of environmental protection and sustainable development (low consumption of natural aggregates, energy, and cement savings, reduction of heavy machinery usage, and the possibility of partially replacing cement with fly ash, thus utilizing by-products of combustion).
How is Foam Concrete Produced?
Foam concrete is produced by injecting mechanically generated foam into a cement slurry/mix. The foam is obtained using a foaming agent of synthetic or organic origin.
Producing foam concrete on-site using a continuous production machine (left) and the foam concrete production scheme according to patent EP 0286149 A2.
The method of production affects the parameters of the obtained mix and the hardened foam concrete, so each use of foam concrete (in bridge construction, road construction, etc.) should be preceded by a proper analysis of the entire technological process of mix production, as well as checking the delivery conditions to the target site and testing the mix, hardened foam concrete, and the performance parameters of the foam concrete in the structure.
Source: Marta Kadela, Ph.D., D.Sc., Professor of the Institute, Building Research Institute Łukasz Chady, M.Sc., Zakład Produkcji Różnej, Handlu i Usług „WAJM” sp. z o.o.