The decay of plastered surfaces: guidelines for the recovery of historical facades by in situ polimerisation

The knowledge of the building is required in order to evaluate the needs of the interventions in the recovery of the plastered façades and to optimise investments in the preservation of the buildings. An informative system able to correlate physical-chemical parameters with different levels of decay on aged plasters has been developed. The decay has to be associated with the origin of the defects and with their growth in time. An adequate simulation of the phenomenology of the decay permits a prediction of the life cycle of the material and therefore a careful program of intervention. The present study illustrates the results of the analytical techniques performed on plastered façades of historical buildings in Campania (Italy). This to identify the methods and the rules that have to be complied in the recovery of the historical plastered buildings. In particular, the pozzolanic masonry used in the Carthusian Monastery of San Lorenzo - Padula (Campania), is degraded by the action of several factors that allow a process of de-cohesion of the materials and of reduced adhesion of the degraded layer. During the recovery process it is necessary to restore the original mechanical properties by improving adhesion and cohesion of the degraded materials It is also desirable to protect the manufactured plasters from further action of atmospheric agents by using a product that reduces water penetration. Polymeric products represent a valid method for the protection and the consolidation of plasters, even though they have difficulties in penetrating the smaller pores of the pozzolanic materials, as they are macromolecular. To improve the penetration of the polymeric products in the manufactured plasters the in situ polymerisation could be proposed. In fact it is better to absorb by capillarity monomers such as acrylic, epossidic or urethans monomers instead of polymers and subsequently polymerise these monomers inside the pozzolanic materials. Therefore, it is possible to improve both the penetration of the polymer into pozzolanic materials and their resistance to atmospheric agents. The study individualises the guidelines in the inspecting activities for the diagnosis of the decay of the plastered surfaces and the guidelines for the recovery of the façades in historical buildings using polymeric materials.