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.

In order to realize the stability of steel fiber inside ultra-high performance Concrete (UHPC) under vibration and improve the use efficiency of fiber, bentonite is used as auxiliary cementitious material in this study. The influence of bentonite dosage on the mechanical properties of UHPC matrix and the mechanical properties and microstructure of ultra-high Performance fiber Reinforced Concrete (UHPFRC) is explored. On this basis, the functional relationships between the distribution and orientation of steel fibers, the freshness of the matrix and the rheological parameters of UHPC are established, and the evaluation model of the service efficiency of steel fibers is established. The results show that with the gradual increase of bentonite incorporation, the use efficiency of UHPFRC steel fiber increases first and then decreases, and when the cement content of bentonite was 2.5%, 5.0%, 7.5% and 10.0%, the flexural strength of UHPFRC increased by 9.0%, 17.6%, 18.5% and 6.1%, respectively. In addition, the increase of bentonite content will lead to the continuous decrease of the fluidity of fresh UHPC slurry (from 261 mm to 100 mm). When the bentonite content is 10.0%, the UHPC slurry has almost no fluidity (100 mm), which leads to the appearance of pores in the UHPC matrix and the decrease of compressive strength.

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