Microscopia petrográfica: aplicação da técnica para investigação da porosidade do concreto

Abstract

Petrographic microscopy is one of the optical techniques used to study the porosity of materials that is processed for the identification of rock-forming minerals and several studies reveal its potential for the analysis of concrete. Such a technique is still little explored in Brazil, but quite developed around the world. The purpose of the present work is to verify the use of petrographic microscopy techniques in determining the porosity of cellular concrete samples. Concretes were analyzed with different percentages of air content to verify the potential of the method. Thus, it was produced a cellular concrete with different foam percentages: 0%, 20%, 30% and 40%. The thin section slides taken from cellular concrete samples are impregnated with a blue epoxy dye, subsequently photographed with the usage of a petrographic microscope and then analyzed using an Image Processing and Analysis and Digital (PADI) software. It was revealed by this study that the impregnation occurs only in macropores and mesopores, which it does not penetrate in the microporosity and ultramicroporosity of the paste. However, with help of PADI techniques it is possible to it is possible to work around the problem and perform pore detection efficiently. The quality of the pore distribution, homogeneity or heterogeneity, is analyzed by studying the coefficient of variation. This work demonstrates the effectiveness of the technique for investigating the porosity of concrete.