Many aesthetically-pleasing architectural shapes are difficult to cast, and require a close collaboration between the formwork supplier, architect, engineer, and contractor to devise the most optimal and cost-effective engineering solution. The main challenge with difficult architectural shapes is not only how to form them quickly and cost-effectively, but also how to maintain the necessary consistency during construction, says PERI South Africa Technical Manager Riaan Brits.

It is for this reason that PERI has developed Rundflex, its flagship product for circular and curved formwork, adds Senior Project Engineer Andrew Rowe. “Rundflex is a highly variable solution for a range of architectural requirements and features,” he says.

Formwork solution for curved walls

Rundflex consists of pre-assembled standard panels for curved walls that can be adjusted to suit the required radius, with no modification work on the panel. A template and spindles with self-cleaning hexagonal threads make adjustment quick and easy.

The pre-assembled panels allow for a maximum permissible fresh concrete pressure of 60 kN/m². Six panel heights are available (0.60 m, 1.20 m, 1.80 m, 2.40 m, 3.00 m, and 3.60 m) as well as three panel widths (external: 2.50 m, 1.28 m, and 0.85 m). Panel connections and compensations up to 10 cm are possible with the BFD alignment coupler.

Rundflex was used by WBHO Construction in 2015 to transform the derelict Silo Building at the Victoria & Alfred Waterfront in Cape Town into the Zeitz Museum of Contemporary Art Africa. This project’s main construction challenge for the formwork supplier was the fact that the existing silos had to be re-sleeved with a 350-mm-thick concrete layer, to a very small radius of under 2.5 m, with an average silo height of 33 m. The concrete sleeving also had to incorporate various splays.

Rowe says that Rundflex was ideal for the continuous adjustment of the tight inner radii needed as the silo re-sleeving progressed vertically. This had to be carried out in conjunction with an integrated PERI BR platform system to allow for the safe installation of the Rundflex panels by crane.

Each silo was built up in 2.5 m high vertical forming sections. The day after each circular wall section was cast, the Rundflex system was removed from the silo in question, and placed on a cleaning deck, where the formwork was cleaned and serviced prior to it being deployed again. 

Rundflex allows for flexible adjustment of wall internal radii of 1 m and larger, and has determined tie points and horizontal extensions up to 7.80 m panel heights. Components for working and concreting scaffolding, as well as for providing support, are available.

Image credit: https://www.peri.com/en/products/formwork/wall-formwork/rundflex-circular-wall-formwork.html


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