Viscoelastic and tensile failure properties of asphalt-mineral filler mastics in brittle-ductile region

The viscoelastic and tensile failure properties of asphalt-mineral filler mastics in the brittle-ductile region were determined. A total of ten mastic systems including five free asphalt volumes and two particle sizes was prepared for testing. The linear viscoelastic behavior of asphalt-mineral filler mastics was demonstrated employing the bending beam rheometer. The Boltzmann superposition principle was verified to be applicable on asphalt-mineral filler mastics. Asphalt-mineral filler mastics stiffnesses at different stress levels were found to be comparable to each other at the same temperature and loading time. It was concluded from the applicability of Boltzmann superposition and stress-independence that the asphalt-mineral filler mastics are linear viscoelastic materials.;The rheological properties of asphalt-mineral filler mastics were characterized by employing a nonlinear regression model. It was shown that this model could be also used to describe the linear viscoelastic behavior of asphalt-mineral filler mastics in the brittle-ductile region. Adding mineral fillers into asphalt cements would move the rheological response to longer loading time, thus, stiffening the asphalt binder.;The tensile failure properties including tensile failure strain, tensile failure strength and tensile failure energy were enhanced by adding mineral fillers. The tensile failure strength could be adequately predicted using the model developed by Leidner and Woodhams (1974). With increasing tensile strength, it implied that there was a good adhesion between mineral fillers and asphalt binders.;The testing procedures of the bending beam rheometer and the direct tension device have been demonstrated to be applicable to determine the rheological and tensile failure properties of asphalt-mineral filler mastics. Hopkins and Hamming's procedure (1957, 1958), and Smith's theory (1976) were successfully used to calculate the relaxation modulus for the responses from BBR and DT respectively. The comparison with the relaxation modulus from both tests showed that the relaxation moduli computed from the data of the direct tension tests were comparable with these calculated from the creep response under the bending beam tests at small strain levels. It implied that asphalt-mineral filler mastics exhibited a linear viscoelastic behavior up to failure points at small strain levels.