Study on the correlation between aggregate skeleton characteristics and rutting performance of asphalt mixture

While the rutting performance of asphalt mixture is largely affected by the skeleton characteristics of the aggregate, the relationship between skeleton formation and rutting performance is not adequately understood. This study experimentally investigates the whole process of asphalt mixture skeleton formation by employing multilevel mixing gradation design method and digital image processing technology on three mixtures. The strength formation process of the mixture is analyzed by performing a laboratory test to establish the dynamic stability estimation model. Results indicate that a small discontinuity in gradation is helpful to enhance the density of the mixture even though skeleton formation and skeleton embedding are not necessarily correlated. With successive mixing of finer aggregate particles, the void ratio and Voids in the Mineral Aggregate (VMA) of the mixture were decreased continually but the stability and dynamic stability were increased. The number of contact points increased firstly and then decreased, and the inclination angle decreased monotonically. The number of contact points should be controlled within a reasonable range during the gradation design. However, a small initial inclination of aggregates possesses a higher dynamic stability. The estimation model proposed in this study could distinguish the influence of the asphalt type for mixtures with the same initial skeleton characteristics.