Estudo da agressividade do ar atmosférico de Fortaleza/CE

Abstract

Reinforced concrete structures degrade more rapidly when located in environments of marine atmosphere due to the influence of chlorine ions present in the saline mist, which, together with the climatic conditions propitiate deleterious action in these structures, and can trigger the corrosion process of their Armor According to Portella (2013), the limits of separation between the marine and urban environments have not yet been established in the city of Fortaleza / CE, so there is a need to know the concentration levels of chlorine ions present in the atmosphere of the city. Such knowledge will allow the development of projects of structures in reinforced concrete that deal in a preventive way the appearance of corrosion of the reinforcement by the action of chlorine ions, emphasizing for the durability of the constructions. Thus, the objective of this work is the quantification and evaluation of chlorine ions content in the atmospheric air of the city of Fortaleza-CE, in relation to the distance of the sea, besides the analysis of the penetration of chlorides in concrete bodies. For the quantification of chlorine ions content in atmospheric air, the wet candle method, described by NBR 6211 (ABNT, 2011), was used to determine the content of chloride in the concrete. The procedure described in ABNT NBR 14832 was used (ABNT , 2002). In order to collect data, a grid was established on the city map where 46 data points were established for distances of 50m, 250m, 500m, 1000m, 2000m, 4000m, 6000m and 8000m in relation to the sea, where The moist sails were installed and exposed for a period of twelve months. Within this mesh, 12 points were chosen for the placement of concrete specimens, which were exposed for a period of six months. It has been found that the content of chlorine ions in air decreases as a function of sea distance. It was noticed that the behavior of the aggressiveness occurs in a different way within the city, because Praia do Futuro presented results much superior to those of Praia de Iracema and superior also of other cities in Brazil and in the world. From the comparative analysis, the results with NBR 14643 (ABNT, 2001) and NBR 6118 (ABNT, 2014) proposed a classification for the environmental aggressiveness of the city, placing most of the coastal region of the city with the Strong Aggressiveness (Class III) and the Praia do Futuro region with Very Strong Aggressiveness (Class IV).