Cement asphalt composite binder(CACB)is a type of composite binder composed of cement,asphalt,water,and various additives through curing,whose creep properties are influenced by asphalt aging.By CACB creep tests at various aging times,the creep compliance curves of the material were obtained.Curves of the test results were fitted by the creep compliance of Burgers model revised by fractional derivative,and the effects of asphalt aging and mix proportions on the CACB creep properties were analyzed.This study demonstrates that as aging time increased,the ability of the CACB to resist instant elastic deformation and viscous flow deformation was enhanced,the amount of its elastic components increased but the viscous components were reduced,and the material deformability decreased,exhibiting deforming properties similar to elastic materials.The effects of asphalt aging on the CACB viscoelastic mechanical properties were great during the initial aging stage(within 12 h)and became weaker during the later aging stage(over 12 h).During the initial aging stage,the CACB creep deformability could be enhanced by increasing asphalt application.However,during the later aging stage,asphalt application had little effect on creep deformability.
A stress extremum method is developed based on Von Karman equations for analysis of membrane wrinkles in this paper. A mechanical model is also established for analyzing shear membrane wrinkles. Expressions of wrinkling wavelength,amplitude and angle are obtained in terms of the stress extremum method. A numerical analysis approach-directly disturbing method is proposed to analyze the configuration parameters of shear membrane wrinkles by introducing out-of-plane disturbing forces to trigger wrinkle formation,while it timely removes the applied forces in order to eliminate the effect of disturbing forces on analytical results. The simulation results agree well with analytical results,which demonstrate that the proposed approach is capable for analyzing the membrane wrinkles with good accuracy.
