Wind power: accelerating tower production

FreiLacke supplies the Max Bögl corporate group with a polyaspartic system for concrete/hybrid towers


The demand for wind power is booming. In order to keep up with changing market demands, the Max Bögl construction company is focusing on increasing its tower production throughput. And for that it relies on an ultra-fast-drying polyurea system from FreiLacke.


Whether the transrapid rail line in Shanghai, metro stops in Amsterdam or Berlin’s central station – the Max Bögl Group has already succeeded in turning these, along with many other large-scale projects, from vision to reality. Nestled in Sengenthal within the Upper Palatinate region, the Max Bögl Group was founded in 1929 as a masonry company and is currently in its third generation of family ownership.

Wind power is a relatively new cornerstone of its operations: the Upper Palatinate-based company supplies modular towers consisting of three-metre-high concrete rings that are topped off by metal tips. And now the special feature: each ring is made up of three individual parts and is fully patented by the construction company. This makes transporting the components much easier – a standard truck trailer is all that is needed.

Around 30 concrete rings are stacked on top of one another and braced together before the approximately 60-tonne metal tip – a true heavyweight – is placed on top. For this reason, assorted rings are manufactured using a special type of concrete with steel reinforcements that can permanently withstand heavy loads.


Coating system for fresh concrete

Since March 2022, the family-run company has been using a new coating system for its concrete elements. It is an ultra-fast-drying material with a polyurea base supplied by FreiLacke. “We were able to point to our broad range of experience gained from our work in the wind power industry, and not just our expertise in towers”, explains Andreas Löffler, FreiLacke’s head of international business development.

At the facility in Segenthal, the concrete components are separated after hardening and then transported directly to the paint shop. “Special coating systems are needed because a certain quantity of residual moisture remains in the concrete. In addition, the parts may remain warm after separation due to the reaction heat of the concrete”, explains Holger Roth, Max Bögl’s production manager. The polyurea-based polyaspartic coating systems from FreiLacke optimally fulfil these requirements and enable the coating to be applied immediately.

In Max Bögl’s paint shop, the concrete rings are transported onto platforms on an automatic conveyor system. Here, the concrete surfaces are prepared and filled – and the cycle time is currently still about one hour. In addition, any pores and cavities may also be sealed in order to achieve the best possible coating adhesion. Various products may be used for this, including FreoWind’s light-grey filler.

Next comes the top coating, which is applied as standard using the Airless or Airmix procedure. At the end of the cycle, the coating will be completely dry and therefore ready for all the remaining steps.


Two applications against stress cracks

The coating primarily serves to boost the visual appearance of the components, but the finishing layer also provides them with an outstanding mechanical strength and dirt-repellent properties.

Two additional workstations in the hall are used for carrying out finishing work on the heavyweights. When this work is complete, the components are stored outdoors in their fully coated state. They are now permanently exposed to the wind and weather – with the best-possible protection.

The construction company switched to the FreiLacke system with the primary goal of increasing its concrete component production throughput due to the high demand for new wind power systems – the war in the Ukraine has acted as a catalyst for this, explains Andreas Löffler. As a result, the company is planning for a significant boost to its production figures from this summer and onward.


Rheological adjustments for simple processing

As Andreas Löffler has already explained, the switch to the new coating system was a straightforward procedure, and an application technician had also joined him on site in Sengenthal. Only the coating supply for each ring main required a small amount of pre-planning.  “Employees have actually thoroughly enjoyed working with the system”, says Löffler, “as the primer filler is especially easy to handle and is also very well-suited to the current application technology – our colleagues at FreiLacke’s head office in Bräunlingen-Döggingen/Black Forest have worked meticulously on the rheological adjustment.”

Furthermore, Max Bögl has also been actively involved in wind power itself: Bavaria’s most powerful wind turbine, which features a tower supplied by Bögl, was commissioned in the Winnberg area of the Neumarkt district in 2011. With a total height of 180 metres and a power input of 3.4 megawatts, the turbine produces more than one third of the overall power that the community uses. And what’s more, the specifically established Max Bögl Wind AG and system suppliers GE Wind Energy have held the record for the highest wind turbine in the world since 2017. The company in Upper Palatinate supplied the towers for four wind turbines in Gaildorf/Baden-Württemberg at a hub height of 178 metres and an overall height of 246.5 metres.

Hybrid tower Bögl 2.0.jpg Max Bögl relies on the fast-drying coating system from FreiLacke


PM Max Bögl_Beispiele Schichtaufbauten.jpg Layer structure example (comparison of two possible processes)