Abstract
The article studies the unsteady-state creep of a dense fine-grained road asphalt concrete prepared using a bitumen of grade 100-130 by penetration at direct tension at different stresses and temperatures.Creep experiments were performed in two specially designed and assembled installations with thermal chambers (T=60℃…-24℃).For the mathematical description of creep curves, a model is proposed in the form of a power function with a normalized time argument with three physical parameters: ξ is the parameter of hardening, t1 is the period of hardening; ε1 is the limiting strain of hardening.It has been established that the nature of "the limiting strain of hardening-stress" dependence is different in different temperature ranges, which is explained by the ratios of the contribution of the parameters ξ and t1 to the deformation process.The socalled "kinetic characteristics" have been newly introduced which characterize the intensity of a stress effect on the parameters ξ and t1.Three characteristic intervals have been established in the temperature dependence of the kinetic characteristics, within which the asphalt concrete is in viscoelastic, viscoelastoplastic and viscous-flow states, respectively.Analytical expressions have been found for the rates of unsteady-state and steady-state creep, shear viscosity of the asphalt concrete, including only the parameters of the unsteady-state creep ξ, t1, ε1.