Combined modification of asphalt with organic attapulgite (OATT) and polyurethane (PU): preparation, properties and modification mechanisms

Polyurethane (PU) and attapulgite (ATT) have been proven to have good effects on asphalt modification. This study proposes to use both PU and organic attapulgite (OATT) to prepare a modified asphalt, aiming to improve the comprehensive performance of asphalt and study the synergistic modification effect of PU and OATT on asphalt. Firstly, the structure and composition of ATT and OATT were determined by X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy. Then the OATT/PU modified asphalt was investigated in terms of compatibility, basic physical properties, high- and low-temperature rheological properties, and high-temperature stability. Results indicated that the organic modifier was successfully grafted onto ATT. OATT and PU present a good synergy in asphalt and play a significant role in improving the high- and low-temperature performance of modified asphalt. The addition of OATT led to significant and consistent improvement in the high-temperature performance of the OATT/PU modified asphalt. At the same time, the increase of OATT content also helps to improve the low-temperature performance of the modified asphalt. Finally, the optimum contents of modifiers are recommended. The modified asphalt 3 wt%OATT/7wt%PU is suggested for areas with long duration of high temperatures, while 3 wt%OATT/9wt%PU is suggested for areas with long duration of low temperatures.