改性沥青剪切松弛模量在复频域的零极点特性OA

The stress relaxation and creep compliance functions of modified asphalt are typically continuous time signals.Their unique properties in the complex frequency domain obtained through the Laplace transform provided a new approach for investigating the linear viscoelastic behavior of modified asphalt.The influencing factors on the linear viscoelastic range of asphalts and their zero pole characteristics of the shear relaxation modulus were analyzed using the strain amplitude sweep and stress relaxation experiments.Results show that when the strain amplitude was below the critical value,the storage modulus,loss modulus,and phase angle of asphalt remained constant,exhibiting linear viscoelasticity.However,when the strain amplitude exceeded this value,the modulus decayed rapidly and the phase angle increased sharply with the increase of strain amplitude,demonstrating nonlinear viscoelasticity.At 20℃ and 10 rad/s,the maximum critical strains corresponding to the linear viscoelastic regions of asphalt rubber,polymer modified asphalt,and matrix asphalt were determined as 2.57％,5.3％,and 5％,respectively.The linear viscoelastic region of asphalt rubber was narrower than those of matrix asphalt and polymer modified asphalt.Additionally,the stress relaxation response system function of asphalts in the complex frequency domain had 1 double zero and 3 poles.A pole was located at the left half of the real axis,representing the exponential decay part in the stress relaxation response;A pair of conjugated poles corresponded to the exponential attenuation of triangular oscillations in the stress relaxation response.In addition,the peak and valley in the stress relaxation transformation modulus curve corresponded to the poles and zeros of the transformation modulus,respectively.