Design and performance evaluation of Bi-block precast rubberized epoxy asphalt trackbed for railway

With the objective of improving the construction efficiency and provide excellent performance of railway trackbed, the dry-mixed rubberized epoxy asphalt mixture (DREAM) was proposed to prepare the bi-block precast epoxy asphalt trackbed structure. Based on the coarse aggregate voids filling method combining the similitude method for gradation design of coarse aggregate and Superpave method for gradation design of fine aggregate, the gradation of mixture was determined. To analyze the feasibility of proposed asphalt trackbed material for railway structure, the fatigue test under 3 million repeated loadings and semi-circular bending test under the effect of aging and freeze-thaw cycles were conducted. After comprehensively understanding the test results, it was concluded that the DREAM with 11 wt% crumb rubber (CR) exhibited a better fatigue and fracture resistance compared with another type of DREAM with a lower content of CR, i.e., 9 wt%. Owing to a larger amount of CR, the DREAM with11 wt.% CR owned an outstanding ability of deformation recovery and ductile failure. Therefore, it was determined to be an effective asphalt trackbed material. Once the designed DREAM was selected, the corresponding bi-block precast epoxy asphalt trackbed finite element model was generated by using the ABAQUS software for the life-time deformation analysis through the time-temperature superposition principle. The numerical study and calculation of time-temperature conversion indicated that the train loading was mainly responsible for the permanent deformation. The value of permanent deformation caused by the train loadings was two times higher than that caused by static loading (e.g., steel and fastening).