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.

Enhancing Effect of Waste Engine Oil Bottom Incorporation on the Performance of CR+SBS Modified Bitumen: A Sustainable and Environmentally-Friendly Solution for Wastes

Waste engine oil bottom (WEOB) is a hazardous waste whose effect as an additive to CR+SBS modified asphalt is rarely studied. In this study, the CR+SBS asphalt binder was modified with WEOB in different concentrations (3, 6, and 9 wt%). The GC–MS and FTIR were performed to evaluate the chemical compositions of WEOB and WEOBCR+SBS asphalt. The results showed that the main constituents of WEOB were similar to the functional groups of asphalt, along with maleic anhydride (MAH). Pavement performance-related rheological tests such as RV, temperature sweep (TS), FS, MSCR, and BBR were carried out. Results show that WEOBCR+SBS-6 exhibited the best high- and low-temperature property, followed by CR+SBS-3 and CR+SBS-9. Fluorescence microscope (FM) test, bar thin layer chromatograph (BTLC) test, FTIR, and AFM tests were carried out to evaluate the micro-morphologies and modification mechanism. The analysis revealed increased trends in resin fraction as opposed to asphaltene fraction with the increase of WEOB content. FTIR analysis revealed that the amide groups in WEOBCR+SBS asphalt bonded to the free radicals of CR. Moreover, a modification mechanism was elaborated. WEOB strengthens the cross-linked structure of CR+SBS polymers, reacting with SBS to graft onto MAH-g-SBS, and the free radical of CR interacts with the amide group in WEOB to form a bond. In addition, the content of lightweight components and surface roughness of SBS specimens were in good correlation, which contributed to the rutting resistance and adhesion and self-healing performance.

Study on the Melting Temperature of CaF2-CaO-MgO-Al2O3-TiO2 Slag under the Condition of a Fixed Ratio of Titanium and Aluminum in the Steel during the Electroslag Remelting Process

During the process of electroslag remelting (ESR) of steel containing titanium and aluminum, the activity ratio between titania and alumina in CaF2-CaO-MgO-Al2O3-TiO2 slag must be fixed in order to guarantee the titanium and aluminum contents in the ESR ingots. Under the condition of fixed activity ratio between titania and alumina in the slag, the melting temperature of slag should be investigated to improve the surface quality of ESR ingots. Therefore, this paper focuses on finding a kind of slag with low melting temperature that can be used for producing steel containing titanium. In the current study, the thermodynamic equilibrium of 3[Ti] + 2(Al2O3) = 4[Al] + 3(TiO2) between SUS321 steel and the two slag systems (CaF2:MgO:CaO:Al2O3:TiO2 = 46:4:25:(25 − x):x and CaF2:MgO:CaO:Al2O3:TiO2 = 46:4:(25 − 0.5 x):(25 − 0.5 x):x) are studied in an electrical resistance furnace based on Factsage software. After obtaining the equilibrium slag with fixed activity ratio between titania and alumina, the melting temperatures of the two slag systems are studied using slag melting experimental measurements and phase diagrams. The results show that the slag systems CaF2:MgO:CaO:Al2O3:TiO2 = 46:4:25:(25 − x):x, which consists of pre-melted slag S0 (CaF2:MgO:CaO:Al2O3 = 46:4:25:25) and pre-melted slag F1 (CaF2:MgO:CaO:TiO2 = 46:4:25:25), can not only control the aluminum and titanium contents in steel, but also have the desired low melting temperature property.

Validation of Adhesive and Temperature Property Characteristics of Microsurfacing by Performance-Based Mixture Design Approach

Performance-based mixture design of microsurfacing offers a promising solution to the best application of asphalt emulsions. The presented study investigated a novel approach to evaluate the spalling resistance and high and low-temperature resistance of microsurfacing. The laboratory tests, including mixture bond strength (MBS), driving wheel pavement analyzer (DWPA), multi-stress creep recovery (MSCR), load wheel rutting (LWR), and single edge notch beam (SENB) were conducted to characterize the performance-related properties; the response surface method (RSM) was used to obtain the optimal proportions of the mixture. According to the experimental results, the performance-based mixture design method improves the comprehensive performance of microsurfacing, such as adhesion at high and low temperatures. The results of RSM show that temperature is the most important factor that affects the adhesion of mixture. There is a strong correlation between adhesive and temperature performance detected by different test methods. Due to different chemical mechanisms caused by cement and emulsified asphalt, the high-temperature performance index of the microsurfacing mixture is lower than that of HMA. Furthermore, the low-temperature resistance is analyzed and suggested indicator is proposed.