Linear viscoelastic behaviour of thermosetting epoxy asphalt concrete - Experiments and modeling

This paper presents an investigation into the linear viscoelastic behaviour and rheological model for epoxy asphalt concrete (EAC). The complex modulus test was used to characterize the linear viscoelastic properties including dynamic modulus and phase angle. Strain sweeps were performed to determine the linearity limits of EAC at various temperatures and frequencies. Complex modulus tests were conducted at strain level well inside the linear region at temperatures of 5, 20, 30, 40, and 60 °C and frequencies of 0.1, 0.5, 1, 5, 10, and 25 Hz for each temperature. Master curves of dynamic modulus and phase angle were developed based on time-temperature superposition principle, respectively. Effects of air void content and binder content on the master curves of dynamic modulus and phase angle of EAC were evaluated. The linear viscoelastic behaviour of EAC over the range of frequencies was modeled by Huet-Sayegh rheological model. Results show that EAC exhibits typical linear viscoelastic behaviour at low strain magnitude. The linearity limits are temperature and frequency dependent. A strain magnitude of 150 (×10−6) can be accepted as the linearity limit of EAC at various temperatures and frequencies. EAC shows considerable susceptibility to air void content and binder content. The increasing air void contents result in lower dynamic modulus and higher phase angles. EAC with binder content of 6.5% has the lowest phase angle master curve. The results also show that there is good agreement between the measured complex modulus values and results of analytical calculations obtained from the Huet-Sayegh model. Hence, the Huet-Sayegh model can be successfully used in describing the linear viscoelastic behaviour of EAC over a wide range of frequencies.