A bold concrete structure built entirely with DUO formwork

Over the past year, a concrete structure has slowly emerged amongst a more conventional residential setting in East Sussex. The single-storey structure is the first self-build project the owner, Adrian Corrigall, has ever built. At the same time, it’s also PERI’s first housing project with DUO in the UK.
 

The inspiration behind Concrete House stems from Adrian’s experience with concrete throughout life, from riding bikes and skateboards in skate parks at a young age, to developing a keen interest in Brutalist architecture more recently.

In many ways, the project disrupts traditional methods of construction, making them more efficient or convenient for labourers. The choice of formwork is one of the methods that challenges the norm in building methodology. The entire cast in-situ concrete structure has been formed using DUO, a technopolymer plastic formwork system, instead of traditional timber or heavy steel shuttering throughout.

PERI worked with augmented reality software and produced drawings in 3D to facilitate the design stage. By doing this, the developer and sub-contractor were able to understand the relationship between formwork, concrete pressure and the site before construction started. A major benefit of visualising DUO in-situ ahead of the build was that issues could be identified and construction output optimised.

From the onset, the idea was to use DUO panels for horizontal and vertical applications to form slabs, columns and walls. The lightweight panels, the largest weighing no more than 25kg, were ideal for the project due to its location and confined site space.

Labourers were able to lift and move the panels around the site by hand, eliminating the need for a crane to erect the system. Furthermore, DUO aligned with Adrian’s vision of reducing waste during construction. All of the raw material is 100% recyclable and can be reused in the production of new panels, making it a sustainable alternative to using conventional formwork on this project.

The system also offered logistical benefits. Due to the weight of the panels, only three lorries were required to deliver material from PERI’s depot to the site.

PERI’s technical team had to control the balance between achieving the architect’s design requirements and ensuring that the arrangement of DUO shutters was compatible with the system’s limitations. In addition to formwork design, seamless construction and a steady supply of concrete  is crucial when achieving a consistent finish. Resilia is a fibrereinforced self-compacting concrete mix. Due to its fluidity, the concrete exerts a higher pressure than conventional concrete. Panels were limited to a maximum pressure of 50 kN per sq m.

In order to work within these limitations, concrete had to be poured in a controlled manner, especially as this was a unique mix that had never been used with the system and formlining before. The consistency of the mix enabled concrete to flow naturally into the complex formwork shapes, without requiring vibration.

Although self-compacting concrete has a high flow rate, delays in the concreting process can affect the finish as the mix starts to solidify. Regular deliveries from a local production site reduced the chances of this occurring on the project. This was complemented by the fact that the number of DUO shutters erected on site justified the volume of concrete delivered for each pour. Overall, the concrete mix and formwork worked well together to create the bold and unique finish that was desired.