New composite reinforcing grid enables thinner concrete façade panels

A 3-D carbon fiber reinforcement developed by SGL Group and V. FRAAS Solutions in Textile GmbH helps reduce thickness required for concrete facade panels used in building and construction.

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A 3-D carbon fiber reinforcement recently developed by SGL Group - The Carbon Co. (Wiesbaden, Germany) and V. FRAAS Solutions in Textile GmbH (Helmbrechts, Germany) has recently proven its worth. SGL reported on Aug. 16 that it is possible to produce concrete façade panels only 26 mm/1.02 inches thick using a “carbon grid” as internal reinforcement. The grid consists of two plies of carbon fiber scrim spaced 12 mm/0.47 inch apart that are connected by compression-resistant pile threads. A steel-reinforced facade panel of similar size reportedly has a minimum thickness of 100 mm/3.94 inches — the extra thickness is necessary to prevent corrosion of the steel due to water ingress by way of cracks in the concrete.

The thin facade panels were installed on a new factory for Alphabeton AG in Büron, Switzerland, an innovative specialist in concrete products manufactured from high-performance and ultrahigh-performance concrete (UHPC). A ventilated façade “curtain wall” was installed on the building, with a total area of 450m2/4,844 ft2. The wall comprises 350 panels, each measuring 865 by 1,620 mm (34 by 63.8 inches), with a thickness of 26 mm/1.02 inches. The building, appropriately, houses a precast concrete element production line.

“We were looking for a solution that would enable us to produce thin concrete façade panels in large dimensions,” says Alphabeton’s Hans-Peter Felder, who is responsible for R&D. “The new 3-D carbon fiber grids impressed us with their light weight and corrosion resistance and were easy and convenient to process.”

Peter Weber, VP of sales and marketing for SGL’s Carbon Fibers & Composite Materials business unit, adds, “In this application, we particularly exploit the corrosion resistance of our carbon fibers. Thanks to this advantageous property, we can dispense with the thick concrete covering obligatory with steel-reinforced concrete to prevent rust and produce thin concrete elements.”

V. FRAAS has developed a production plant in which the new 3-D textile reinforcement is manufactured with SGL’s SIGRAFIL C carbon fibers, in large dimensions. The structural grids are also being used in the repair and renovation sector and in bridges and buildings, says V. FRAAS.