Validation of the Time-Temperature Superposition Principle (TTSP) in the Non-linear Domain for Bituminous Mixtures with Reclaimed Asphalt Pavement (40% RAP)

Abstract

The test campaign was carried out on cylindrical samples of bituminous mixtures with 40% RAP. This percentage of RAP is still considered to be the maximum in most study cases. The generalization of the TTSP is first proposed when considering small strain domain (for strain amplitudes below about 100 µm/m). We had measured the complex Young’s modulus (E*) and complex Poisson’s ratio (ν*) during cyclic loadings, performed with ENTPE’ experimental device. The analog model 2S2P1D (2 “Springs”, 2 “Parabolic elements”, 1 “Dashpot”), developed by ENTPE, was used to simulate the three-dimensional linear viscoelastic behavior of the tested material. The 3-directional (3D) thermo-mechanical behavior is then totally characterized with a master curve (plotted at a reference temperature) and a shift factor (aT), function of the temperature. The Time-Temperature Superposition Principle (TTSP) is then verified with a good approximation. Then, we had performed specific experiments (direct tensile test) on the same material to generalize the behavior in the nonlinear domain (ε ≈ %) of the TTSP considering the 1-directional (1D) and the 3-directional (3D) thermo-mechanical behavior. The time-temperature superposition principle (TTSP) was validate with the same shift factor (aT).