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Research on time-temperature-ultraviolet ageing degree superposition of asphalt mortar based on DMA test

ABSTRACT Many research studies have been conducted on the ultraviolet (UV) ageing performance of asphalt and asphalt mixture, but the superposition relationship between the loading time–temperature and the aggravation of UV ageing degree is still lacking. In this research, the dynamic modulus of styrene butadiene styrene (SBS) polymer-modified asphalt mortar, under different UV intensities, UV ageing time and loading temperatures, was obtained by the dynamic modulus sweep test at different temperatures. The results showed that the dynamic modulus decreases with the increase of temperature, and increases with the increase of UV ageing time and intensity. To further evaluate the UV ageing of asphalt mortar, the time–temperature superposition has been expanded to incorporate the UV ageing time and intensity, and the dynamic modulus curves of asphalt mortar under different UV ageing time or intensities and temperatures were constructed through superposition shift equations. The results showed that the reduced UV ageing time or intensity increases with the decrease of test temperature. Based on the superposition relationship of time–temperature–UV ageing degree (radiation time and intensity), the comprehensive shift factor functions were determined. These superposition equations conducted in this research provided meaningful predictions for different UV ageing time and intensity conditions.