Concrete formwork Parapluie

Lightweight and delicate concrete formwork

A bus stop canopy made of ultra high-strength concrete. The Parapluie is an architecturally sophisticated, highly innovative concrete formwork designed for the series production of bus stop roofs. The realization of this filigree, only 25mm-thick structure made of ultra-high-strength concrete from DUCON with multi-layer micromat reinforcement was achieved by means of a high-precision mold construction from ACCENTFORM.

The authors involved received the Tsuboi Award 2013 for their outstanding engineering achievement at the 2013 IASS Symposium: Philipp Eisenbach (Bollinger + Grohmann), Ragunath Vasudevan (schneider+schumacher), Manfred Grohmann, Klaus Bollinger and Stephan Hauser (DUCON).

A parametric form-finding process was used to develop a system that transfers the loads of the shell via membrane effects. The result of intensive research, development and testing is a concrete shell that is as light as it is strong, with an edge thickness of less than 25 mm.

Only the outstanding engineering performance of the offices involved in conjunction with the implementation by experts such as ACCENTFORM made such a project possible.

ACCENTFORM’s path to the perfect shape – in four steps

1. since extremely stable and cost-effective forms are required for the production of economical concrete formwork beams, a stable timber substructure (made of glulam beams) with a cover plate is produced first. This substructure enables a reproducible chip support during subsequent milling and leads to an even and safe load transfer during the actual concreting process.

2. large-volume STYROPOR blocks are then glued onto the wooden substructure. The cost-effective STYROPOR blocks fill the gap up to the actual functional surface.

3. the STYROPOR structure is pre-milled with undersize and then coated with a paste or a PU hard coating. This creates a hard surface that guarantees high compressive strength.

4 The coating must be milled a second time to maintain the exact surface geometry. The resulting surface is finely sanded by hand and then varnished. High-gloss surfaces can also be achieved with an additional polish.

New dimensions

The combination of ACCENTFORM’s precision in form construction with the design and engineering services of the participating offices and DUCON’s special material opens up countless further possibilities for producing ultra-thin concrete shells through parametric form optimization. The high-performance and micro-reinforced concrete can be used to create extremely thin and equally load-bearing structures, whether for furniture, ceilings or façades. Engineers and architects alike can benefit from this if they are looking for technically feasible, innovative design language.

Project details