Efeitos dos sulfatos na degradação do concreto

Abstract

One of the most outstanding research fields today is the study of the durability of materials due to their economic and ecological importance and their interrelationship with the questions of quality and user satisfaction, which is manifested in the requirement of maintaining an adequate performance. This work has as objective the characterization of the attack on the concrete by sulfate ions, the influence on the durability, focusing on the mechanisms and the effects caused on the structures built with this material. The aggressiveness of the environment with the presence of sulphates where the concrete structures may be inserted, can significantly reduce their lifespan in urban, marine, industrial, sanitary sewage, among others. These ions promote chemical reactions with the hydrated compounds of Portland cement which, in advanced stages, cause the formation of expansive products that then generate the cracking and disintegration of the concrete. The main argument that underlies this study is that water is important in the synergy of concrete degradation, and that in order to produce durable concrete, the amount of water in the trace must be reduced and its access prevented during the utilization time of the structure. Another important point is related to the economic impact, since the financial costs for the restoration of buried structures usually demand higher values than in aerial structures. This paper seeks to analyze the best ways to prevent or minimize sulphate attacks on concrete structures. The methodology of this work was made through bibliographic research, which based on these considerations, was studied and deepened the subject on the behavior of concrete against the attack of sulfates, where it was found that it can increase the resistance of concrete against the sulfate attack through: reduction of a/c factor; using sulphate-resistant cement with low tri-calcium aluminate (C3A) content; introducing appropriate proportions of active silica, fly ash, granulated slag and microsilica; Also, in case of a strong attack, the use of an impermeable film that prevents contact of the deleterious agents with the structure itself. It can be seen that the best protection against sulphate attacks is the quality of the cement, specifically the low permeability and the increase of the content of this binder per cubic meter of concrete produced.