Influence of Nano-Al2O3 on the Evolution of Molecular Weight, Morphology, and Rheology of SBS-Modified Asphalt

Abstract

The modification technology of asphalt binder based on nanomaterials has been widely adopted in the field of pavement engineering. This study mainly explored the feasibility of nano-Al2O3 for styrene-butadiene-styrene (SBS) asphalt modification from the perspective of property and mechanism, based on its high-temperature resistance and chemical stability. The effects of nano-Al2O3 on the high-temperature rheological properties, low-temperature rheological properties, and bonding properties of SBS asphalt were analyzed by performance evaluation tests, including the dynamic shear rheometer (DSR) test, bending beam rheometer (BBR) test, and binder bond strength (BBS) test. The results showed that nano-Al2O3 could improve the high-temperature property and bonding property of SBS asphalt while retaining its low-temperature property. In addition, the micromechanisms of nano-Al2O3/SBS composite–modified asphalt binder were revealed from the perspectives of functional groups, molecular characteristics, and microscopic morphology by gel permeation chromatography (GPC) tests, Fourier transform infrared (FTIR) spectroscopy tests, and atomic force microscopy (AFM) tests. The analysis showed that nano-Al2O3 was physically blended in the modification of SBS asphalt binder. Based on the chromatogram and weight-average molecular weight analysis, it was found that nano-Al2O3 increased the molecular weight of polymer groups and asphalt macromolecular groups in SBS asphalt. AFM image analysis showed that the number and the volume of bee structures in SBS asphalt and the roughness increased after modification by nano-Al2O3.