A STATISTICAL APPROACH FOR MANAGING VISUAL INSPECTION AND IN SITU TESTING IN DESIGNING REHABILITATION PROJECT OF A 5 KM LONG VIADUCT

摘要

A 120 spans five km long viaduct on the A19 highway Catania -Palermo in Sicily (Italy) was considered for a rehabilitation project by the Italian National Road Administration. In consideration of the great extension of the viaduct and in order to optimise the rehabilitation cost a detailed visual survey and in situ inspection campaign was carried out. Potential mapping, carbonation and chloride profile determinations on concrete cores and concrete compression strength determination on concrete cores were extensively used as diagnostic techniques. The great amount of obtained data allowed a statistical evaluation of structural members degradation. Potential mapping was extensively used to evaluate corrosion of prestressing steel in beams. Four different potential values distributions were obtained for the following beam areas: heads of the left and right edge beams, heads of the internal beams and central zone of the beams. In spite of the good concrete quality, a mean carbonation depth of 16 mm being evaluated on the beams after 30 years, extended degradation of the beam heads was observed as a consequence of a poor detailing in beam design and inadequate drainage systems.