Survey, diagnostics, monitoring methodology and digital twin for the conservation of the facade of the church of Santa Maria di Nazareth in Venice

This contribution aims to illustrate the experimental research linked to the restoration concluded in 2018 for the conservation of the façade of the Santa Maria di Nazareth church in Venice and the ongoing monitoring methodology for the evaluation of its conservation state over time. The baroque façade is unique in Venice as it is entirely made of Carrara marble, a limestone with a saccharoid structure which has proved over the centuries unsuitable for the aggressive lagoon climate, given the complex architectural conformation and the unfavourable environmental conditions in which the façade is inserted. The state of conservation of the marble at the beginning of the last worksite showed widespread and worrying degradation in many parts, especially in the more protruding ones: in fact, the stone surface reached detachment and pulverization by simple contact. The ultimate goal was to achieve a compatible and retractable conservative restoration for a possible improvement of the conservative results over time and also to facilitate an effective retrieval of scientific data in case of future interventions. With this aim, once the construction site was completed, a survey campaign with the purpose of reproducing a digital twin through 3D modelling was planned, to monitor the façade to have an exhaustive knowledge of the possible vulnerabilities present, with the involvement of the VIDE laboratory of IUAV University of Venice. A data acquisition protocol has been developed for the preservation of cultural heritage, thus guaranteeing an uninterrupted knowledge of the material degradation and of the structural situation