Situated in front of the famous Parc des Princes sports facility, the Jean Bouin Stadium was designed by Rudy Ricciotti to be light and airy. Thanks to Ductal®'s combination of superior properties, it was possible to construct a thin, lightweight envelope and waterproof roof from 3,600 self-supporting Ductal®/UHPC panels.
The remarkable envelope consists of three main areas:
- a perforated façade, with self-supporting lattice panels that permit the light to filter through to the interior
- transition panels between the roof and the façade, with a higher perforation rate and larger curvature
- the roof, made from 1,600 panels with glass inserts
A total of 18 molds were required to produce the 3,600 UHPC panels. For a full year, the precaster (Bonna Sabla) cast thousands of panels at a rapid pace of more than 18 per day.
A comprehensive series of tests prior to the casting
"Preparation for the assessment involved a painstaking process to create a full-scale prototype that would undergo a series of laboratory trials and tests: wind fatigue with 78,000 flexion cycles, thermal shock, soft and hard shock, 50 frost and de-frosting cycles simulating between 30 and 50 years of the structure's life span, along with continuous water tests on the panels to check their watertightness" explains Guillame Lamoureux, co-founder of Lamoureux Ricciotti Ingénierie.
"The use of 35 mm plate elements helps with directional dispersion of the fibres" explains Dominique Corvez, Head of UHPC/Ductal® North America. "Ideally, the fibres needed to flow smoothly into the moulds and fully resist developing loads by having preferential orientation in the matrix. Several panels were tested by cutting small section samples of the UHPC out of each panel in order to prove that the casting process consistently produced correct fibre orientation and therefore viable precast elements for Bonna Sabla."
Innovative roof panels with glass inserts
Another architectural requirement for this project was a waterproof roof system. When producing the roof panels, the glass pieces were first positioned into the moulds and then the UHPC material was cast around the glass. Waterproofness was guaranteed with a silicon joint placed around the glass before casting.
Thanks to Ductal®'s mechanical performances, it was possible to create the thin, triangular panels with 20 to 27% glass. Its high flexural resistance also permitted the design of a slender roof, with an 8 to 9 m overhang.
The defined thickness of the elements (35 to 45 mm) helped with directional dispersion of the fibres. "Ideally, the fibres needed to flow smoothly into the moulds and fully resist developing loads by having preferential orientation in the matrix. Several panels were tested by cutting small section samples of the UHPC out of each panel in order to prove that the casting process consistently produced correct fibre orientation and therefore viable precast elements for Bonna Sabla", explains Dominique Corvez.
The façade panels, an exterior lattice mesh
Ductal®,allowed the thin lattice panels (some just 11 cm thick) to have more than 50% open space. Blended with metal fibres, the material's superior mechanical performances also allowed the lattice to function as a balustrade.
Dimensions of the façade panels: 9 m x 2.5 m with a minimum thickness of 11 cm
Dimensions of the roof panels: 8/9 m x 2/2.5 m and 35/45 mm thickness
The use of the same light grey Ductal® UHPC material for the roof and façade panels, cast in a controlled plant environment, resulted in high-quality elements with consistent coloring and guaranteed aesthetic coherence throughout the entire envelope.