Influence of aggregates properties on microstructural properties and mechanical performance of asphalt mixtures

Abstract

Asphalt mixtures can perform suitably in road and airfield pavements. However, with rapid increases in traffic volumes, harsh climate environments, and heavier loads, there is an increased interest in improving the mechanical properties of asphalt materials through a suitable design of the microstructure of the asphalt mixture. Aggregates’ physical and chemical properties significantly influence the interface interaction between aggregates and binders and achieve strong, durable and cost-effective asphalt mixtures. This study prepared the asphalt mixtures from three different aggregate sources, i.e. Granite 1 (GD 1), Granite 2 (GD 2) and limestone (GD 3) and captured the microstructural properties using a charge-coupled device (CCD) digital camera and analysed them by iPAS software. The effect of the daily temperature variation of the environment to the corresponding temperature gradient through the depth of all asphalt mixtures layers was assessed. The results indicate that sodium oxide (Na2O) + potassium oxide (K2O) + calcium oxide (CaO) + silicon (SiO2) has a significant influence on the electrical conductivity of granite samples at high temperatures and pressure. Marshall, wheel tracking, three-point bending beam, double tension–compression fatigue tests at two periods were conducted to investigate any relationship between the structural performance of the asphalt mixtures and their microstructural properties. Additionally, the normal contact fabric tensor (F) was developed to t evaluate the interlocking of aggregates in asphalt mixtures, and the correlation with the mechanical performance was performed. The results show that the higher amount of silicon and aluminium in aggregates, the better the aggregate texture and the high contact points weight. In addition, high contact points weight has a notable impact on the Marshall stability, rutting depth, dynamic stability, stiffness modulus and complex Poisson’s ratio at high and low temperatures. All samples showed good mechanical performance at all temperatures because of their high aggregate particles F.