Time-temperature superposition for asphalt mixtures with growing damage and permanent deformation in compression

The objective in this study was to check the validity of the time-temperature superposition principle for hot-mix asphalt (HMA) with growing damage and viscoplastic strain in the compression state, which is essential for the permanent deformation characterization of HMA. Constant crosshead rate compression tests were conducted at temperatures between 25degreesC and 55degreesC, and data were analyzed to construct the stress-log reduced-time master curves for various strain levels. Research results indicate that HMA with growing damage remains thermorheologically simple in the temperature range used in this study and that the time-temperature shift factor is only a function of temperature and is independent of the strain level. Two types of tests, the repeated creep and recovery test and the cyclic sinusoidal loading test, were performed in this study to validate the time-temperature superposition in loading histories commonly used in asphalt mixture testing. The results further confirm that the time-temperature superposition is valid for HMA with growing damage and permanent deformation and that the response of HMA depends only on the reduced loading history.