Influence of asphalt mixture workability on the distribution uniformity of asphalt, aggregate particles and asphalt film during mixing process

Abstract

Due to the homogenization of asphalt mixture, the service life and road performance of asphalt pavements are found to be seriously affected by the segregation of the asphalt mixture. The distribution mechanism of the asphalt on the aggregate as well as its distribution uniformity are also considered as major issues in the construction of asphalt mixtures during the mixing process. Accordingly, the present study aims at investigating the distribution uniformity of asphalt, aggregate particles, and asphalt film during the mixing process of asphalt mixture. Furthermore, the study intends to explore the effect of workability on the mixing uniformity of the mixture. To achieve these goals, a workability evaluation method was presented for the assessment of the asphalt mixture. In addition, using combustion furnace, scanning electron microscope (SEM), standard sieve, etc., the mixing uniformity was analyzed by evaluating the asphalt distribution uniformity (ADU), homogeneity of aggregate (HA), and coating uniformity of asphalt film (CUAF). Also, applying linear correlation, the correlation between workability and ADU, HA, and CUAF was determined. The obtained results corroborated the applicability of the proposed asphalt mixture, workability test equipment and evaluation metrics. The distribution of the asphalt and aggregate in the upper and the lower layers of the mixing pot was also found to be more severe than that of the different directions of the pot. Moreover, the existence of more coarse aggregates in the asphalt mixture was shown to result in a greater degree of aggregate dispersion. The homogeneity of the asphalt film was also observed to be greatly affected by the mixing temperature. Finally, the mixture’s workability was found to have a significant impact on the ADU, HA, and CUAF of the mixture.