Investigation on the High- and Low-Temperature Performance of Organic Rectorite and Polyurethane Composite-Modified Asphalt Binder

Organic rectorite (OREC) can significantly improve the resistance of asphalt to deformation and aging, but it tends to cause low-temperature cracking. To solve this defect, a novel idea that develops an OREC and polyurethane (PU) composite-modified asphalt binder has been put forward in this work. Various modified asphalt binder systems containing different combinations of OREC and PU contents were prepared by the melt blending method. The storage stability of the OREC/PU-modified asphalt binders was studied. The high- and low-temperature properties of binders were investigated by dynamic shear rheometer and bending beam rheometer tests. The microstructure and modification mechanism of the binders were characterized by gel permeation chromatography, differential scanning calorimetry, and Fourier transforms infrared spectroscopy. The results showed that the OREC/PU-modified asphalt binder displayed good high-temperature storage stability. However, excessively high content of OREC will adversely affect the storage stability of asphalt. In the 2% by weight OREC/9% by weight PU modified asphalt system, OREC and PU exhibited excellent synergistic effects. And the high- and low-temperature properties of the asphalt were significantly improved. The introduction of OREC/PU reduces the Tg of the asphalt binder and the enthalpy during temperature change. The modified asphalt has good low-temperature flexibility through the physical and chemical interaction between polyurethane and asphalt during the modification process. PU can intercalate OREC and react with active hydrogens in asphalt to generate cross-linked structures to enhance the high- and low-temperature properties of the asphalt binder.