Caracterização microestrutural de matrizes asfálticas de agregados finos a partir da microtomografia computadorizada

Abstract

The fine aggregate matrix (FAM) has been regarded as key constituent of asphalt mixtures. Recently, different FAM mix design procedures have been proposed for the fabrication of isolated FAMs that are representative of the material existing within asphalt mixtures. However, there is no consensus on which of those produce FAMs that are in fact representative, given that several important parameters are still assumed, instead of objectively determined from laboratory tests. In that sense, this study proposes the development of a methodology for the identification of air voids corresponding to FAMs in asphalt concrete mixtures from images acquired using X-ray micro-computed tomography (micro-CT) and digital image processing (DIP) with segmentation techniques based on artificial intelligence models. The results indicated a strong correlation between the total air void content in the asphalt concrete mixture and the air voids in the FAMs. In addition, it was observed that the size and distribution of the voids along the specimens were affected by the nominal maximum aggregate size (NMAS) of the aggregates. Additionally, a high correlation was also found between voids measured with the microCT and the laboratory conventional method. It is expected that this research contributes with the advancement on the knowledge about FAM mix design procedures and for the fabrication of testing specimens that are representative of the material existing in corresponding asphalt mixtures.