Asphalt Aggregate Adhesion: Study of the Influence of the Morphological, Chemical and Mineralogical Properties of Different Aggregates from Southern Brazil

The proper characterization of the materials is therefore paramount for the adequate selection and use in design and execution of paving projects. One important property of the asphalt concrete is the binder-aggregate adhesion, consequence of the physical-chemical interaction between the bitumen and the aggregate surface, which keeps the elements together under traffic loads and water flow. A study was conducted to evaluate the morphological, chemical and mineralogical properties of aggregates from 12 quarries used in the production of dense asphalt mixtures in southern Brazil, as well as the interaction of the aggregates with the respective bituminous binders. The rock samples were evaluated and classified employing various methods, including Petrography, X-ray Fluorescence, Digital Image Processing (DIP) using the AIMS 2 system, traditional aggregate characterization tests, and adhesion to the bituminous binder. It was observed that acid rocks, with high Silicon content and less rough, with larger mineral size and lower AIMS values, exhibit worse performance in the visual adhesion test. The Fe/Si and Ca/K ratios were also identified as good indicators to anticipate the aggregate behavior when evaluating the adhesion to the bituminous binder. Comparative analyses based on the results from Petrography, XRF, AIMS2 and adhesion to the bituminous binder culminated in development of a scale ranking that can be used to classify the visual adhesion from terrible to excellent. Thus, it is presented as a good indicator of the behavior of the materials when evaluated the variations in the degree of adhesion allowing the correct selection of materials by the designer.