The performance of an engineering material is determined by the relationship between the stress and the strain in the material. Asphalt binders and asphalt mixes are viscoelastic materials which can be characterized, in the linear viscoelastic domain, by various dynamic material functions. With the new AASHTO pavement design guide, the complex modulus is one of the material functions to be studied. This paper deals with the study of the use of the linear viscoelastic theory to obtain the complex modulus master curves in asphalt mixes based on small amplitude oscillations (dynamic modulus) at different temperatures and frequencies. Three different configurations of dynamic modulus tests on cylindrical samples loaded axially were analyzed: compression, tension, and compression/tension. The dynamic modulus using uniaxial extension or compression-extension produced similar values for the temperatures and frequencies used. The complex axial dynamic modulus in uniaxial compression mode resulted in higher values when the sample was tested at low frequencies or higher temperatures. The feasibility of using dynamic modulus tests on asphalt mix cylindrical samples, loaded in uniaxial compression mode, was shown. The linear viscoelastic description of asphalt mixes seems to be possible when this test is used. The limits of the linear viscoelastic domain and the validity of the time-temperature superposition principle for the master curve in asphalt mix were confirmed. Furthermore its was found that the storage and loss moduli, and horizontal shift factors for the Superpave? and SMA mixes, prepared with the same asphalt binder, are very similar. The dependence of Poisson’s ratio on frequency and temperature was observed. Thus the role of Poisson’s ratio in the constitutive equation has to be studied further.
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