Evaluation on the Performance of Hydraulic Bitumen Binders under High and Low Temperatures for Pumped Storage Power Station Projects

Abstract

The high and low-temperature performance of five hydraulic bitumen binders was evaluated using the dynamic shear rheometer (DSR) test, infrared spectrum test and direct tensile (DT) test. These hydraulic bitumen binders were respectively applied for several pumped storage power stations (PSPS) projects that were constructed or under construction. In order to relate the bitumen performance to the mixture performance, the slope flow test, three-point bending test and thermal stress restrained specimen test were carried out on hydraulic asphalt mixtures. The test results indicated the DSR rheological master curves can well distinguish the difference of each bitumen binder as well as the effect of polymer modification. Phase angle master curves, black diagrams and infrared spectra all indicated that several penetration-grade hydraulic bitumen binders were not virgin bitumen binders but were modified with relatively lower SBS polymer content when compared with traditional SBS-modified bitumen. When selecting the commonly used Karamay SG70 hydraulic bitumen as a reference, the normal SBS-modified bitumen was superior to other bitumen in terms of low- and high-temperature performance. Several slightly SBS-modified bitumen binders did not always show consistent results, which indicated that slightly modified bitumen may not really have the desired performance as expected. Therefore, SBS-modified bitumen will be more promising when dealing with extremely low or high temperatures. Bitumen performance was well compared with the mixture performance by using the bitumen creep, relaxation and tensile failure strain corresponding to the asphalt concrete slope flow, the maximum bending strain and the failure temperature, respectively. Compared with the traditional penetration, softening point and ductility test, it indicated that the DSR rheological test, creep test, direct tensile test and stress relaxation test can be used as more powerful tools for the characterization and optimization of hydraulic bitumen binders.

Laboratory Investigation of Storage Stability and Aging Resistance of Slightly SBS-Modified Bitumen Binders

“…Since Jingbo PMB was known as normal polymer modified bitumen with about 4% SBS polymer content, it implies that Jingbo SG70, Jurong SG90, and Liaohe SG90 belong to the type of slightly SBS-modified bitumen. These analysis results were in agreement with the previous studies based on the FTIR test and the DSR rheological test [ 35 ].…”

“…Karamay SG70 bitumen was virgin bitumen, while Jingbo SG70 bitumen, Liaohe SG90 bitumen, and Jurong SG90 bitumen binders were not pure virgin bitumen binders but were slightly SBS-modified bitumen binders that contained a low content of SBS polymer (approximately 2%). This has been demonstrated in the previous studies using the FTIR test and DSR rheological analysis [ 35 ]. Jingbo PMB was polymer-modified bitumen with a normal content of SBS polymer (approximately 4%).…”

“…Finally, a smooth master curve over a wide range of frequencies was established. More information on how to construct the master curve can be found in [ 35 ].…”

“…Jingbo PMB was polymer-modified bitumen with a normal content of SBS polymer (approximately 4%). More detailed information on the related properties of these five bitumen binders, as mentioned above, can be found in the literature [ 35 ].…”

“…The addition of a relatively low content (for example, 2%) of SBS polymer into base bitumen can well balance the technical indexes at low and high temperatures, and it is found to be flexible and practical to produce bitumen with different penetration degradations. This makes the application of slightly SBS-modified bitumen possible, and it has been demonstrated in several PSPSs [ 35 ]. Due to a lack of fundamental research performed on slightly SBS modified bitumen, concerns arise on the modification mechanism, long-term effectiveness, storage stability, and aging resistance.…”