LE FRATTURE NELLE PIETRE DEL PANTHÉON DI SOUFFLOT: UN PROBLEMA STATICO E DI CONSERVAZIONE DELLE DECORAZIONI

In the practice of restoration of historical buildings, the structural retrofit is often considered as an operation separated from the surface preservation, and is usually carried out by different experts. This is a wrong attitude, as it should always be considered that static problems influence surface conservation and that structural retrofit has often heavy consequences also on the aesthetics of the buildings. A clear example of this strict correlation can be seen in the French Panthéon, in Paris, built at end of the XVIII century in stone masonry reinforced with iron clamps. The cracks that in the latest decades caused the detachment of stone fragments from the ceiling and the partial closure to the public, were first related only to the water infiltrations and to the subsequent corrosion of the clamps, thus only local interventions were carried out. Recent studies have indeed showed how the crack pattern is related to the low ductility of the reinforced masonry, and that without this static problem, water couldn’t have reached the iron clamps. Thus the preservation of the surface stone decorations requires not only the elimination of the water infiltrations, but also the reduction of the structural deformations that first brought to the crack openings. The safeguard of the Panthéon, in which every stone is at the same time architectural and decorative component, must therefore pass also through the static retrofit of the structure.