The micro-sandblasting technique as a new tool for the evaluation of the state of conservation of natural stone and mortar surfaces

This work concerns a feasibility study about the possibility to evaluate the state of conservation of the monumental and historical stone and mortar surfaces with a micro-sandblasting system composed by a micro-sandblasting device and a micro-photogrammetry. The former creates a shallow crater on the surface operating at constant conditions (pressure of the jet, distance nozzle-surface), while the latter let us to quantify the volume of the crater through a 3D digital reconstruction. The work was focused on the validation of the methodology selecting the best operative conditions. To this aim, a set of tests were carried out on small glass specimens followed by tests made on natural stone materials and mortars. The results obtained have outlined the repeatability of the data and the possibility to discriminate among natural stone materials and mortar having different physical characteristics and mechanical behaviours.