The Schöck Combar framework, at the heart of the Paoli-Calmettes Institute in Marseille

Schöck thus unveils another sector of application for its frame solution and consolidates its expertise, illustrated during heritage restoration projects, such as the Givrand church, or civil engineering with the construction of Grand Paris Express tunnels.

A revolutionary high tech device weighing several tonnes ...

ViewRay's "MRIdian Linac" is one of the first devices worldwide to provide high-precision images of the inside of the body in real time using magnetic resonance tomography. The irradiation targets only the tumor, with the ability to follow it even if the target organ moves due to breathing, thus preserving the surrounding tissues and reducing the risk of side effects: an undeniable asset in the treatment of forms of soft tissue cancer (mobile tumors) such as the brain, lungs or digestive tract.

The result of an investment of 8,2 million euros, this flagship of radiology had to benefit from a durable, non-magnetic base to support its 10 tonnes (including 3.400 kg of superconductive magnets).

... supported by a complex of Schöck Combar fiberglass frames

Thus, to take over the 2 kg / m400 load required for this type of structure, the slab was reinforced with the Schöck Combar fiberglass reinforcement.

"The MRidian Linac emits a strong magnetic field and is very sensitive to electromagnetic disturbances that can affect the accuracy of the imagery", explains Jean-Luc Galéa in charge of the construction of the IPC treatment room, designed by the architect Jean-Marc Hullet. And to continue: “No material containing iron should be used in the safety zone, the said 5 Gauss line around the device, a prerequisite also applying to the reinforcement of concrete. We therefore opted for Schöck Combar in synthetic material reinforced with glass fibers which meets all technical requirements while holding reliable certifications. ”

In fact, Combar (from "composite rebar", composite rebar) was developed by Schöck in the 1990s as a replacement for steel in concrete. Bars of diameter from 8 to 32 mm have a design tensile strength, for a durability of 100 years in concrete, certified to 445 N / mm². These values ​​have obtained general technical approval from the Deutsche Institut für Bautechnik (DIBt), a procedure similar to that of the European Technical Assessment (ETE).

Non-magnetic and non-magnetizable, Schöck Combar is not electrically conductive and has a very low thermal conductivity, which makes it an ideal solution in the hospital sector (MRI) where there must be no induction current or obstacle to sensitive medical devices.

An octagonal cavity 5 mm in diameter, 400 mm deep, was previously dug (more than 600 tonnes of concrete was removed on this occasion) in the existing concrete slab of the treatment room at MRIdian Linac. Then, seals were made on the upper, middle and lower parts of the eight sides. On each high and low cutting edge, 35 Schöck Combar bars, 9 mm in diameter and 12 mm in length, were positioned to serve as reinforcement anchors. Then, at mid-height, 1 bars of diameter 000 mm and 5 mm in length make it possible to take up the shear loads.

"We have installed 12 mm diameter Schöck Combar trellises which serve as upper and lower reinforcement", explains the entrepreneur Stéphane Roldan. “The rods are solid and yet easily machinable. The clips, cable ties and plastic spacers supplied simplified assembly, allowing work to be done quickly and precisely. ”

Then it was enough to pour the concrete to reconstitute the raft, in just a few days and in an occupied environment: a performance made possible thanks to the easy implementation of Schöck Combar reinforcements which, with a density of 2,2 gr / cm3, are clearly lighter than steel (7,85 gr / cm3). Note also that they are also distinguished by their resistance to chemicals and their anti-corrosion properties.

With this new achievement at the heart of the Paoli-Calmettes Institute in Marseille, Schöck Combar is further expanding its field of applications to replace steel where it reaches its limits.