Proposta de avaliação qualitativa para o monitoramento do aerosol marinho

Abstract

Chemical attack on facade surfaces and reinforced concrete steel by chlorides is one of the most common causes of pathologies in buildings in coastal regions, where the concentration of salts in deposits produced by sea spray is high. As a way of helping to prevent these pathologies, this work aims to develop a prototype sensor and monitoring system for the accumulation of saline deposits on building facade wall surfaces. Based on the properties of moderate electrical conductivity of these deposits, under the influence of atmospheric humidity, a sensor with phenolic substrate and copper conductive tracks was manufactured and tested in an external environment, exposed to the atmosphere, to verify its feasibility of application in the proposed monitoring. Furthermore, samples of saline deposits, collected from the glass curtain and the window of an apartment near the Salvador seafront, were analyzed using electrical conductivity determination techniques, scanning electron microscopy and energy dispersive X-ray spectroscopy. According to the results obtained, the collected samples presented electrical conductivity and salinity values within the expected range for exposure to marine aerosols, as well as the presence of sodium chloride, as the main component, according to as observed by the micrographs and elemental composition data found. The normalized resistance values, combined with measurement data obtained during the exposure of the sensor in an outdoor environment, made it possible to validate the potential for use of the system developed for monitoring environments with high salinity, based on the qualitative estimation of the concentration of chloride ions in the marine atmosphere. In contrast to classical analytical methods, such as the wet candle method, which require a reasonably long exposure time to the environment under study, reaching up to one month of exposure for an accurate assessment, the method studied in this work has the advantage of providing a qualitative assessment in a practically immediate response time.