evaluation of moisture transfer in external plaster finishings to improve their conservation

The aim of the research is the development of a method for the evaluation of water absorption and moisture transfer in external building components, in particular plaster finishing of historic buildings. The method is based on the characterization and assessment of the water behaviour in mortars performed through different tests: in laboratory on mortars samples to study the hygroscopic and capillarity absorption properties and in situ, based on the use of non destructive techniques such as Infrared Thermography. The investigations provide input data which are useful for simulating moisture transfer to model the physical mechanisms which occur on the façade. The method has a direct application in the conservation plan of Lavello Convent, situated on the shore of Como Lake in Northern Italy: the researchers studied different mortars mix design to identify the best solution in terms of durability and compatibility respect to the masonry underneath. The same mortars have been tested both on site and in laboratory. The case study is part of a larger plan aimed at identifying strategies to increase the service life of the components minimizing the environmental impacts; interventions, maintenance and monitoring programs were firstly defined with the aim of reducing the risk factors, such as water absorption. In fact the researchers are studying water-repellent protective treatments to apply on the plaster outer surface; the systems mortar/treatment are currently under investigation to evaluate the efficacy and the possible harmfulness of the treatment itself