Long-lasting Formwork Panels
Wood-based materials are employed as formwork panels to a large extent in concrete construction and in the production of precast concrete components. Unfortunately, however, the stability of wooden formwork panels decreases considerably when exposed to moisture. This limits their service life to 50 to 80 applications. The poor UV resistance of thermoset coatings has an especially adverse effect on the appearance surface of fair-faced, or exposed, concrete structures because of the yellow and brown discolorations. In addition, the subsequent disposal creates problems because of the phenolic and melamine resin constituents in the wooden panels.
For this reason, all-plastic composite panels have been used for concrete formwork for some time. These panels are lightweight, sufficiently stiff, can be nailed and sawn, and manufactured at a low cost. Furthermore, the plastic version has numerous benefits over wooden panels. They are resistant to the effects of weather, moisture or chemicals, and can be recycled completely. Dr.-Ing. Claus Steyer and Dr.-Ing. Olaf Leitzbach report on this in the June issue of the journal Kunststoffe.
The composite panels have a sandwich structure based on a foamed PP core that is faced with high-strength thin-walled skins. Depending on the requirements, these outer skin layers may incorporate aluminum or glass-fiber mat reinforcement. The panel is further protected against the effects of external factors by additional facing layers of PP. Panels can be produced in a continuous manner and have a density similar to that of wood. At the same time, the production system allows for flexible thickness adjustment, so that the panel can be matched to different applications.
The composite formwork panels have been used at construction sites in over 800 instances since the year 2000. During this time, neither the mechanical properties nor the bearing capacity of the panels has diminished. The high abrasion resistance offsets the relatively low scratch resistance, so that the quality requirements for exposed concrete surfaces have been satisfied.
Since the panels can be deformed, the can also be used for round components. Additional applications include use as flooring and interior linings, truck panels, panels for theatre scenery and trade fair displays, container panels, and in shipbuilding and rail car construction. The panels also find use in horse stalls and milking booths. They are further suited for use as floor panels in animal transporters or as sheeting walls to protect against flooding.
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