References

The Synchrotron European Radiation Facility (ESRF) consists of a ring of storage of elementary particles surrounded by an experimental hall of 14 000 m². It has been found that the paving of the experimental hall has undergone differential concrete shrinkage, causing a tiling of the concrete which is incompatible with the paving deflection criterion: 5 μm of amplitude with a source of vibration which can vary between 0,1 Hz and 50 Hz. In addition to the development of plurimillimetric voids under the pavement, other types of disorders were observed: non-planarity of the slabs (up to 1 cm), level differences between slabs, slab angle cracking, joint spalling.

Following an attempt to fill the voids using traditional grout realized in 1992 that turned out to be inadequate, ESRF asked TERRASOL to design a technique for a definitive rehabilitation. After conducting further studies and supervised specific tests, we have decided to treat the damages by injecting low-pressure grout under the pavement using a mesh of 1.5 m x 1.5 m. Three types of grout were used, reaching silica soils, to fill the voids and impregnate the thin sand bedding. In addition, the joints were reconstituted after a shot-blasting engraving and a reloading using an epoxy mortar.

More than 6 years after the end of the works, the solution fully satisfied the researchers on the site. The technique helped to limit the deflections of the paving at a very satisfactory value: except for a slab treated during the early phase of the works which revealed a deflection of about 4 microns in accordance with the specified criterion, a safety factor of 2 could be reached, enabling to compensate for the effects of slabs aging.

Terrasol’s achievements: