Prediction Method of Long-Term Mechanical Behavior of Largely Deformed Sand Asphalt with Constant Loading Creep Tests

AbstractBecause of large pronounced deformation in the compressive creep process of soft sand asphalt, it is necessary that both the true stress and true strain are measured. Accordingly, instead of fictitious creep compliance (FCC), true creep compliance (TCC) relating the true strain to the true stress is used to characterize the viscoelastic properties of sand asphalt in this paper. The relationship between TCC and FCC is described by a second-kind Volterra integral equation (VIE). A prediction method of long-term mechanical behavior of largely deformed sand asphalt with constant loading creep tests is proposed. In this method, the FCC master curves are constructed based on the time-temperature superposition principle, and then the linear VIE from the FCC to the TCC is solved with the collocation method, and the nonlinear VIE from the TCC to the FCC is solved with an iterative formula. Unconstrained compressive creep tests for 3,600 s were conducted on sand asphalt mixture samples in various temperature and nominal stress conditions. As an application example, the long-term creep behavior of sand asphalt at the given reference temperature is predicted with the proposed method.