Laboratory and statistical evaluation of the microstructural characteristics of Sand Asphalt Mortar

One of the problems encountered in asphalt pavements is fatigue damage, which is related to the type of aggregate, the rheology of the asphalt binder and its chemical composition, resulting in the emergence of microcracks and, subsequently, macrocracks. Therefore, this phenomenon needs to be studied from the asphalt binder scale to the complete asphalt mixture. In this sense, this paper focuses on the asphalt binder scale with the objective of investigating the microstructural characteristics of cylindrical samples of Sand Asphalt Mortar (SAM). These samples can be made up of standard sand and any type of asphalt binder. The use of SAM can contribute to obtaining laboratory rheological results representing the real binder film thickness that exists in an asphalt mixture. In this study, SAM samples composed of a polymer binder without aging were compacted with a manual press, resulting in cylindrical specimens with 40 mm of height and 12.5 mm of diameter. Its microstructure was investigated by determining the air voids (AV) and the binder film thickness (FT), considering different binder contents: 6%, 8% and 10% by weight. The results indicated that the samples made with 6% binder present homogeneity in terms of microstructural parameters, and represents more realistically the binder film thickness that will exist in a complete asphalt mixture, can be used in oscillatory tests carried out on the dynamic shear rheometer, and contribute to studies on the asphalt binders.