Characteristics of asphalt modified by waste engine oil / polyphosphoric acid: Conventional, high-temperature rheological, and mechanism properties

The recycling of waste engine oil (WEO) in asphalt not only can save non-renewable natural crude resources, but also can reduce emissions of CO2 and promote ecological economy. This paper attempts to explore the feasibility of utilization WEO and PPA in asphalt modification. The influence of WEO/PPA on the conventional performance, high-temperature rheology of asphalt and modification mechanism was analyzed by conventional test, dynamic shear rheology (DSR) tests, optical microscope observation and fourier transform infrared (FTIR) spectroscopy. Finally, comprehensive performance of asphalt with different combination of PPA and WEO was evaluated by entropy weight method and TOPSIS analysis. The results indicate that the addition of PPA decreases the penetration and ductility, and increases softening point, temperature stability and high-temperature performance of asphalt modified by WEO. Rutting factor of asphalt modified with 2% WEO and 2% PPA has the largest increment of 31.2% compared with that of original asphalt, which shows obvious improvement of high-temperature performance. Analysis of the FTIR indicates that there is a chemical reaction between PPA and asphalt. Additionally, based on entropy weight and TOPSIS analysis ductility has the largest entropy weight suggesting that it affects the comprehensive evaluation most and the comprehensive performance of asphalt with 1% PPA and 4% WEO proportion was better than other binders. In summary, the addition of WEO/PPA in asphalt provides a new way of sustainable development for road materials.