Envelope for centrifuge built in Delft with help from MEVA Radius
Envelope for centrifuge built in Delft with help from MEVA circular formwork radius
A somewhat unusual construction site in the Dutch city of Delft required absolutely precise formwork: the single-story rotunda for a centrifuge must be able to withstand large forces. The MEVA formwork system Radius deployed its qualities to the full to guarantee precise construction of the concrete shell.
With the new centrifuge at the Deltares Institute for applied research in the field of water and subsurface movements, processes are simulated to scale that can take months in reality. This is done by applying high gravitational forces, which represents an acceleration in time for the processes involved in geo-engineering. For example, the failure behaviour of dykes can be optimised and the ageing processes of pile foundations slowed down.
In a container with a volume of two cubic metres, the Deltares Geocentrifuge accelerates research material to a maximum of 300 g. The measured data are converted, validated and enable a wide range of tests to be performed. The customers are government agencies, engineering offices, companies and scientific institutes.
The centrepiece of the system is the centrifuge with an arm length of 5.5 metres. It achieves a speed of 456 km/h and thus up to 3.7 revolutions per second. The building’s concrete shell must be able to withstand the extraordinary forces that act on it. For this reason, the construction company De Hilster Betonwerken had to tackle additional challenges besides creating the building’s unusual shape. For example, stringent requirements were placed on the surface smoothness in order to reduce friction to a minimum and avoid unwanted air turbulences.
This also meant that the wall had to be perfectly round and have exactly the same radius over its entire height, from the ground to the 4.25 m high ceiling of the single-story rotunda. To avoid unevenness, the concrete was poured in one cycle. To provide the 40 cm thick concrete walls with the necessary stability, particularly strong two-row reinforcement was required consisting of 20 mm rods in a 10 cm grid. It was thus necessary to erect formwork with as few tie connections as possible. “Erecting round formwork with such large dimensions was a huge challenge for De Hilster Betonwerken. With the help of MEVA’s expertise, everything went successfully,” reports civil engineer Roy Wubben. 330 m2 of the formwork system Radius were used.
The other concreting work on the construction site was also carried out without any problems at all. First of all, it was necessary to built an air duct under the foundations of the centrifuge equipment using AluStar wall formwork panels. The Mammut 350 system was used to build a right-angled support wall and, in addition, 45 MEP shoring towers were used up to a height of 4.50 m. Roy Wubben: “De Hilster Betonwerken has been working with MEVA for years and has always been absolutely satisfied.”