Análise da influência de diferentes tipos de cimento na resistência ao ataque por sulfatos

Abstract

Concrete is an inorganic composite material consisting of cement mortar and chemical or mineral admixtures. Cement is largely responsible for the chemical reactions that provide the structural properties to the concrete. The sulfate attack involves series of complex chemical reactions between the sulfate ions and the cement hydration products and there are numerous sulfate sources. As the attack occurs in the cement paste, the objective of this work was to study the behavior of different types of cements when exposed to different types of sulfates, by means of visual inspection of the specimens, tests of axial compression strength, sulfate concentration determination, scanning electron microscopy and energy dispersive spectroscopy EDS. A total of 72 specimens were cast with CP II-F-32, CP IV-32 RS and CP V-ARI cements, which were kept for 5 months in contact with CaSO4, Na2SO4 and MgSO4 attack solutions with a 10% w/w concentration. The visual aspect allowed to observe that the samples exposed to MgSO4 solution presented larger external deposits. The results of sulfate content determination showed higher concentrations for CP II-F-32 and CP V-ARI cements. The micrographs and EDS showed that the three types of cement had a larger number of altered structures when in contact with MgSO4. Magnesium sulfate solution was the most aggressive.