Analysis of Microstructural Parameters and Indirect Tensile Strength in Evaluation of Hot Mixture Asphalt Rutting Performance

In recent years, vast extent and severity of permanent deformations has created some concerns regarding the effects of this type of failure on performance of asphalt pavements. To investigate the rutting of asphalt mixtures, it should be noted that these mixtures are multiphase combination of aggregates, binder and voids. Arrangement of aggregate particles (aggregates skeleton) in the internal structure of hot mix asphalt has an important role in mechanical performance of the mixture, especially on its rutting resistance. In most regulations for asphalt mixture's design, only macroscopic parameters such as void content and binder volume, along with mechanical characteristics, such as rutting resistance, are used as the main criteria for quality control. But so far, visual analysis and micro-properties of asphalt mixtures (internal structure of the pavement) have not been considered much. In this article, micro-effectiveness properties of asphalt mixtures such as number of contacts, length of contacts and orientation of contacts for rutting performance of 16 types of mixture (two types of gradation, two types of binder, two types of aggregates and two types of filler) were considered. In this research, the results of rutting resistance (flow number) and micro parameters (as number of contact, length of contact and orientation of contact), determined by image processing (by using iPas2 software), and indirect tensile strength were compared. The analysis showed that rutting performance depends to a large extent on micro characteristics of asphalt mixtures and these properties could be used as a control tool in design of asphalt mixtures.