Gradation design and performance evaluation of modified asphalt mixture for bridge asphalt plug joint design

Abstract

Although the Asphalt Plug Joint (APJ) has been developed for half a century to overcome the maintenance issues in traditional bridges, its shortcomings, such as short service life and poor deformation capacity, have not been overcome. There are currently no adequate specifications in place to guide the material design and performance evaluation of APJs. Therefore, this study proposes a suitable design method for asphalt mixtures based on the mechanical characteristics and performance requirements of APJ. According to the proposed mixture type, the influence of gradation type on the bonding strength, shear strength, and tensile strength of the APJ mixture is explored mainly based on direct shear test, direct tensile test, and meso-structure analysis. In addition, the effect of fiber type on improving the performance of mixture and the influence of temperature on the performance of the mixture are discussed. The test results show that it is recommended to use a skeleton-filled asphalt mixture with a lower void ratio, more fine aggregates, more mineral powder, and more asphalt in the APJ. Similarly, modified asphalt with good high and low temperature performance should be selected, and an appropriate amount of reinforcing fibers, such as polyacrylonitrile fiber and basalt fiber, should be added to the asphalt mixture.