MICROSCOPIC OBSERVATION OF SITES AND FORMS OF ETTRINGITE IN THE MICROSTRUCTURE OF DETERIORATED CONCRETE

Abstract

Determination of DEF in hardened concrete by simply relying on the identification of ettringite with electron microscopy or powder X-ray diffractometry can be imperfect. Those methods have high risk of overlooking other possible deterioration phenomena. In this study, microstructural observation was carried out on concrete samples with cracks in the absence of external sulfate attack, using petrological methods under the polarizing and electron microscopes. This was done to determine the deterioration causes and present the differences in the occurrence factors of ettringite based on the observation results. In addition, observation was also carried out on concrete samples with cracks that were exposed to fly ash using the same methods to determine the deterioration causes and demonstrate the importance of petrological approach.