Tips on preparing an alkus® formwork panel to meet the higher standards of exposed concrete surfaces

The alkus® solid plastic panel is also ideal for meeting the high aesthetic standards of exposed concrete surfaces. The formwork panel needs to be pre-treated prior to initial concreting to ensure the desired quality of the exposed concrete surface. We recommend construction of a mock-up or concrete test set to evaluate the surface quality along with alkus, architects, master builders, formwork manufacturers and concrete suppliers and to define a desired surface together. This is essential if you want the finish to meet all the expectations of building owners.
Below are a few tips on how to prepare the alkus® formwork panel in the best possible way for these applications.
 

What do I need?

  • Compressed air cleaner or broom
  • Schwamborn rotation cleaner with additional weight and abrasive cleaning grit 320
  • Clean water squeegee
  • High-pressure sprayer with stainless steel nozzle
  • Formwork oil (release agent)
  • High-pressure cleaner, preferably with a rotating nozzle

How is the alkus® formwork panel pre-treated for exposed concrete use?

First remove any impurities, such as chips or other dirt, from the alkus® formwork panel – whenever possible, using a compressed air cleaner or, alternatively, with a broom. Then use a Schwamborn rotation cleaner with an additional weight and an abrasive cleaning grit 320. Clean the surface of the alkus® panel intensively, moving the rotation cleaner both crosswise and lengthwise, with a permanent supply of water. Remove any remaining water with a clean water squeegee.
Then apply a fine spray mist of formwork oil to the fully dry surface using a high-pressure sprayer with stainless steel nozzle at an operating pressure of at least 6 bar. The alkus® formwork panel is now ready for concreting. The panel should subsequently no longer be stored for longer periods, as dust and other dirt particles may otherwise collect on its surface. If too much formwork oil has been applied, use the water squeegee to remove excess oil evenly and in just one direction. Make sure not to leave any streaks on the surface. 

How is the alkus® formwork panel cleaned after concreting?

When stripping the formwork, take care not to scratch or otherwise damage the surface of the alkus® solid plastic panel – therefore, always ensure sufficient clearance when lifting the panel with a crane. Do not use a concrete scraper to remove any concrete residue from the panel used for exposed concrete surfaces. It is best to use a high-pressure cleaner, preferably with a rotating nozzle. Remove concrete residue from the alkus® formwork panel using a high-pressure cleaner with a maximum pressure of 1,000 bar. Make sure the nozzle and pressure setting are compatible. After stripping, do not forget to clean and pre-treat the formwork panel again.  

Important 

  • Always treat the alkus® solid plastic panel with great care when preparing it for exposed concrete applications. Scratches or marks, e.g. pencil or shoe marks, may otherwise appear on the surface of the panel and then be visible on the formed surface.
  • The formwork panel is crucial for producing a perfect finish for your exposed concrete surfaces. However, the concrete formula and the formwork oil, as well as its correct application, for example, also play a key role in this process. 
 
Do you have any questions about preparing the alkus® formwork panel for exposed concrete applications? We look forward to hearing from you!
 
This recommendation is intended purely as guidance and offers no guarantee of a perfect outcome. Please note that besides the actual panel, there are a number of other influencing factors that must be observed to achieve the desired finish.
The alkus® formwork panel can be used to construct an exposed concrete finish…
The alkus® formwork panel can be used to construct an exposed concrete finish…
… like here at the offices and commercial property project Tic Tric Trac in Zurich.
… like here at the offices and commercial property project Tic Tric Trac in Zurich.