基于大振幅振荡剪切(LAOS)的沥青非线性流变行为研究

The advanced rheology test platform and the nonlinear rheology methods (Fourier transform rheology and Lissajous curve method) were employed and introduced to investigate the effects of LAOS testing conditions (temperature and rate) and bitumen properties (origin and aging degree) on the nonlinear rheological behavior of bitumen. The results show that the third-order relative harmonic intensity ratio of I₃/I₁ of bitumen at 24 ℃ were much greater than those of the 36 ℃ and 48 ℃ cases, and this index significantly decreases with temperature. Comparisons based on the Lissajous curves and third-order relative harmonic intensity ratio of I₃/I₁ indicate that the nonlinearity of bitumen increases with the decrease of temperature, but increases with the increase of rate. A comparison of two base bitumen binders with the same penetration grade but different origin shows that no significant difference was observed in term of the index I₃/I₁ and Lissajous curves. This means that the origin of bitumen does not significantly affect the nonlinearity of bitumen. Finally, the comparison among unaged, short-term aged and long-term aged bitumen binders shows that with the increase of aging degree, the index I₃/I₁ increases significantly and the Lissajous curves distortion becomes obvious, indicating an enhanced nonlinearity of bitumen with aging.