High-Temperature Property Evaluation and Index Research of Modified Asphalt before and After Aging

In order to better evaluate the composite modified asphalt of composite modified asphalt, this study through dynamic shear rheological (DSR) test, the three kinds of polymer modified asphalt before and after ageing: the compound modified asphalt (CCR), rubber powder modified asphalt (CR) and composite modified asphalt of SBS modified asphalt (SBS) analysis, to explore suitable for composite modified asphalt of modified asphalt evaluation index. The results show that: Compared with G*/sinδ, G*/(sinδ)9 has higher accuracy for evaluating the composite modified asphalt of polymer modified asphalt and is more sensitive to changes in phase angle. The critical temperature of anti-rutting factor TG*/sinδ9 is significantly higher than that of TG*/sinδ, especially for composite modified asphalt. This has an important impact on the PG classification in the Superpave asphalt binder specification. G*/sinδ underestimates the high temperature grade of the modified asphalt. The equivalent viscosity measured with η’ = sinδ-4.8628 G*/ω has the best correlation with the anti-rutting factor G*/(sinδ)9, and the highest correlation coefficient is 0.999, which is more suitable as a high-temperature property evaluation index of modified asphalt.

High- and Low-Temperature Properties of Layered Silicate-Modified Bitumens: View from the Nature of Pristine Layered Silicate

Layered silicates, as bitumen modifiers, have received increasing attention. The main objective of this study was to evaluate the influence of layered silicates on bitumen properties. For this study, montmorillonite (MMT), rectorite (REC), organic montmorillonite (OMMT), and organic rectorite (OREC) were selected. The layered structure type of layered silicates was characterized by SEM (scanning electron microscope) and XRD (X-ray diffraction diffractometer). Tests for determining high-temperature properties included viscosity, DSR (dynamic shear rheometer), and TG (thermogravimetry) tests, and studies for determining the low-temperature properties were conducted by BBR (bending beam rheometer) and DSC (differential scanning calorimetry) tests. Our results show that MMT, REC, OMMT, and OREC were all intercalated structures. OREC had the largest d001 interlayer space, followed by REC, OMMT, and MMT. OREC improved the high-temperature property of virgin bitumen more effectively than OMMT. Meanwhile, REC-modified bitumen exhibited a high-temperature property similar to OMMT-modified bitumen. When compared with REC and OREC, MMT and OMMT were less efficient in reducing the low-temperature properties of virgin bitumen, and OMMT was the least efficient. Therefore, it can be concluded that the nature of pristine layered silicates has a great impact on the high- and low-temperature properties of bitumen. Moreover, organic treatment can simultaneously improve the high- and low-temperature properties of layered silicate-modified bitumens.