Decay assessment and 3D surface modelling of historical brick masonries in Venice

In many noteworthy buildings in Venice we can observe a strong loss of material at the bottom of the façades (usually in the 1-2 meters from the soil level). Capillary rise, water condensation-evaporation sub-florescence of salts can induce scaling and cracking in bricks with a subsequent reduction of the thickness of the wall section and therefore of its load-bearing capacity. This work proposes a new approach to assess the vulnerability of historical brick masonry patrimony, the most used in Venice. This new approach provides for three main steps: i) the minero-petrographic characterization of the materials (bricks and mortars); ii) the 3D photogrammetric survey and the measurements of the cross-sections of brick walls; iii) the decay assessment. For this purpose, the Church of Santa Maria dei Servi (Cannaregio, 14th century) was selected as case of study. Color, mineralogy and texture of the bricks and mortars, and secondary weathering products were studied by means spectrophotometry, X-ray diffraction, optical and scanning electron microscopy, and hyperspectral analysis. 3D surface modelling by empirical descriptions based on photogrammetry was used for understanding the effects of water and salts interaction in the bricks wall of the main façade. Results will be useful to provide previsions of long-term deterioration of that monument and they can be implemented in other brick buildings in Venice, which have the same decay pattern.
AIAr Meeting, Padova, June 29 - July 2, 2022