The thin concrete vault of the Paraboloide of Casale, Italy. Innovative methodologies for the survey, structural assessment and conservation interventions.

The former clinker warehouse, also known as the “Paraboloide” of Casale is an architectural symbol of the concrete Italian industrial heritage. The constructive technology and the structural shape of the thin concrete vault are comparable to the outstanding realizations achievements of the beginning of the XXth century, as for examples the works of E. Torroja and of P.L. Nervi. The metric survey has been achieved using high resolution terrestrial laser scanning technology (TLS), in order to obtain an accurate 3D model with uniform level of detail and precision, in addition to a continuous metric information for each portions and elements of the structure. This procedure allowed a proper reading of the structural typology of the building and the recognition of possible design and construction principles, essential for the conservation project. The laser survey was carried on both intrados and extrados of the huge parabolic vault, performing a high number of scan positions, located inside and along the outer limit of the building. The model processing has been mainly directed to the evaluation and control of geometrical features of the reinforced concrete membrane. The image texturing of the complex surfaces has been performed by the Focus 3D Faro integrated camera, with principal axis coaxial with laser ray. Some other photogrammetric stripes, focused on interesting portions of the structure, enabled to accomplish the detailed inquiries of the shape model with a materials decay analysis. The structural assessment combined a detailed finite element analysis. The analysis was performed with the software Diana (TNO, The Netherlands), accounting for smeared cracking and the presence of reinforcements. Finally, the paper summarizes the main criteria for interventions, according both to structural safety requirements and conservation prescriptions, enhancing the extraordinary innovative value of this particular cultural heritage.