A study on creep and recovery behavior of asphalt binders

• Binder’s response to multiple stress creep and recovery test has been captured.
• Conventional binders are not suitable for higher temperatures.
• Modified binders show delayed elastic response.
• Power law model has been modified to incorporate non-linear viscoelastic response.
• Critical values for ηM and α has been assigned.

This study investigated the strain response of different asphalt binders when subjected to multiple creep and recovery cycles. Test was conducted at three altered temperatures (40, 50 and 60 °C) and four stress amplitudes (0.1, 3.2, 5 and 10 kPa). Burgers four element model and a Power law model were used to simulate the measured response. It was demonstrated that the modified binders outperformed the conventional binders at all the test conditions. Conventional binders were found to be highly sensitive to change in stress level and temperature. It was proved from the test results that the traditional Superpave criteria for characterizing rutting behavior of asphalt binders is not appropriate. Both the Burgers and Power model gave poor experimental fit for the recovery domain, mainly for the modified binders. The viscous parameter ηM of the Burgers model correlated well with the non-recoverable creep compliance (JnR) and R value. The modified Power model, as proposed in the study, was in good agreement with the measured creep and recovery response for all the binders. The new model parameter ‘α’ was found to be able to predict the delayed elastic response of the binders. Critical values of ηM and α were assigned corresponding to different traffic levels and suggested as a rutting measuring tool.