AVALIAÇÃO MICROESTRUTURAL E DE DESEMPENHO DE ADITIVO HIDROFUGANTE PARA CONCRETO

Abstract

The present study had as main objective to evaluate, by means of microstructural analysis (SEM and X-ray spectroscopy), the behavior of a crystallizing water-repellent additive especially indicated for application in concrete. The evaluations were carried out on specimens made of cement paste, adding 2% of the additive, replacing the cement mass, and its results were compared to a reference paste (without water-repellent additive). In addition, in order to assess its mechanical performance and durability, the tests on resistance to axial compression and water permeability were performed, respectively, on concrete specimens (cement, sand and gravel). The microstructural results showed that there was the formation of insoluble crystalline compounds in the pores and capillaries of the concrete, making it difficult for water to penetrate. This fact was reproduced in its resistance to compression, with an increase of 20% in its values, in relation to the reference concrete and, consequently, reduction in its permeability. The formation of these crystals in the voids and interstices from the internal micro- cracking of the concrete has the consequence of making the material denser and, therefore, more impermeable, a fact that was confirmed in the research.