A comprehensive evaluation of the effects of aggregate gradation on the shear strength properties of wearing course mixtures

Abstract

ABSTRACT Based on the continuous maximum density (CMD) theory, the present study investigated the effects of aggregate gradation on the shear strength properties of hot mix asphalt (HMA) mixtures, i.e. the cohesion (C), the internal friction angle (φ), and the compaction slope (K). In addition, this study aimed to evaluate relationships of the shear strength parameters with the rutting resistance of asphalt mixtures. Seven wearing course mixtures were carefully designed to represent a wide variety of dense-, coarse-, and fine-graded mixtures with 12.5-mm nominal maximum particle size. The C and φ values of HMA mixtures were determined using a combination of the unconfined compression test and the indirect tensile test. The K value was also obtained from the data of Superpave gyratory compactor. Furthermore, the wheel tracking test was conducted to assess rutting resistance of the HMA mixtures. The experiments showed that the CMD theory of aggregate gradation has potential applications for evaluating not only aggregate interlock parameters (φ and K) but also the C property of asphalt mixtures. In addition, the statistical analysis demonstrated that a rational model using the C and the K has a strong relationship with the rutting resistance of wearing course mixtures.