Abstract: The interface of the asphalt plug expansion joint pavement and the bridge pavement is the weakest part of the structure of the expansion joint,and the interface properties have a close relationship with the mixture of the expansion joint.Therefore,it is very necessary to investigate the mixture composition design of the expansion joint.In this paper,the gradation and the optimum asphalt-to-stone proportion of the mixture of asphalt plug expansion joints are investigated by the Marshall test,and a compound trabecular specimen is designed to simulate the structure of the expansion joint.Then,by a direct tension test and an oblique shear test,the influences of the cement type,the mixture gradation,the temperature,the interface handling and the loading rate on the tensile and shear performance of the interface are analyzed.The results show that ( 1) the stone of the expansion joint mixture should be of a single particle size,and the optimum asphalt-to-stone proportion is 25%; ( 2) fine aggregate gradation,dry interface,no pollution and a certain roughness are advisable; and ( 3) the temperature rise and the vehicle loading speed decrease can reduce the tensile and shear strength of the interface more easily.

Key words: road engineering, asphalt plug expansion joint, mixture composition design, tensile strength of interface, shear strength of interface