Predictive maintenance for monitoring performance decay of plaster converings according to the criteria of ISO 16686-7 code

The aim of the present work is the construction of the performance/time curve that characterizes and defines the aging of plaster coverings on tuff masonry, a widely used technical solution in the building stock of the city of Naples. 53 sample building were tested; these were selected according to a criteria of homogeneity of the technological characteristics of the support and covering material (tuff masonry + lime-cement plaster + acrylic paint). The year of construction of the buildings, as well as any problem occurred during the work realization, was acknowledged. The described objective represents a result of indubitable utility and practical consequence, as it allows: - the evaluation of the residual service life at the moment of the execution of field tests with fixed methodologies; - the definition of the time thresholds for the execution of the most appropriate interventions, determined in a maintenance plan, in which predictive maintenance of course plays a fundamental role. The chosen methodology for the evaluation of performances, considering the indications of ISO 15686-7, is the infrared thermographic camera test, combined with close-up visual inspections and percussion tests. The activities were carried out through the following main phases: - defining the task; - planning; - examination; - evaluation; - reporting. The results showed the possibility to create curves like the one represented in the annex B of the already quoted ISO 15686-7 and hence to define the decay with 5 performance degrees (no symptoms – slight symptoms – medium – strong symptoms – totally unacceptable, including collapse and malfunction), corresponding to an accurate quantification of the conditions of conservation, and that is mainly possible thanks to the output of the thermographic camera. In relation to the results, different scenarios of planned maintenance for a period of 30 years have been hypothesized.