Effect and mechanism of warm mix agent on the rheological properties of styrene–butadiene–styrene-modified asphalt

Introduction The objective of this study was to investigate the effect and reaction mechanism of warm mix agent PN2217 on the rheological properties of styrene-butadiene-styrene (SBS) asphalt. Methods Fourier transform infrared (FT-IR) spectroscopy and atomic force microscope (AFM) were conducted to reveal the reaction mechanism between PN2217 and SBS asphalt. Dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) tests were performed to analyze the rheological properties of SBS asphalt modified with 1, 3, and 5 wt% PN2217. Results The addition of PN2217 changed the component proportions, reducing phase separation and promoting the formation of a more homogeneous microstructure via crosslinked long-chain molecules. PN2217 improved the temperature sensitivity and permanent deformation resistance of SBS asphalt at high temperatures, mainly by increasing the elastic components. However, the addition of PN2217 reduced the cracking resistance potential of SBS asphalt by 7%–19% and increased stress sensitivity by 4.8%–8.3% at low temperatures. Discussion This deterioration at low temperature may be attributed to the loss of light-weight components.