Comparison of the 3-dim linear viscoelastic behavior of asphalt mixes determined with tension-compression and dynamic tests

In this paper, conventional cyclic tension-compression tests and dynamic measurements have been applied to three cylindrical specimens of asphalt mixes. The results of the two tests have been compared. For the tension-compression tests, the complex modulus was obtained from the measurements of the axial stress and axial strain. For the dynamic testing, an instrumented impact hammer and an accelerometer have been used to obtain the frequency response functions of the specimens at different temperatures. The dynamic complex modulus was then back calculated by optimizing finite element calculated frequency response functions to match the measured frequency response functions. The 2S2P1D linear viscoelastic model was used to estimate master curves of the complex modulus for the two test methods. The two tests give similar results. However, the dynamic measurements give a higher value of the norm of the complex modulus and a lower value of the phase angle compared to the tension-compression results. This result is probably explained by the nonlinearity of asphalt mixes as dynamic tests are performed at a much smaller strain level than the tension-compression tests.