Search Results (9)

In response to the complex pretreatment processes (e.g., solvent dissolution and high-temperature melting) of direct coal liquefaction residue (DCLR) in asphalt, its low-dosage limitation for high-value utilization in asphalt pavement, and the unclear interaction mechanisms between high-proportion DCLR and asphalt, this study comprehensively analyzed the molecular composition and structural characteristics of DCLR at multiple scales using FTIR, GPC, SEM, BET, Tg-FTIR, and XRD. DCLR was crushed to a particle size of 0.15 mm and mixed with 70# base asphalt at mass ratios of 10:100, 15:100, 20:100, 25:100, 30:100, 40:100, and 45:100 at 185 °C to prepare high-proportion DCLR-modified asphalt. The conventional and rheological properties of DCLR-modified asphalt at various dosages were evaluated and compared with those of Buton rock asphalt (BRA)-modified asphalt at equivalent dosages. The results indicated that DCLR and BRA significantly improved the high-temperature performance and PG grade of the base asphalt but reduced its low-temperature performance and grade. At equivalent dosages, DCLR exhibited a more pronounced enhancement in high-temperature performance and a greater reduction in low-temperature performance compared to BRA. High-proportion DCLR-modified asphalt meets the technical requirements for high-modulus asphalt. Using FTIR, GPC, four-component analysis, and elemental analysis, the chemical composition and performance variation trends of high-proportion DCLR-modified asphalt were investigated at multiple scales. The interfacial physical, chemical, and mechanical behaviors between DCLR and base asphalt were characterized. The interaction mechanisms between high-proportion DCLR and asphalt were elucidated, and a novel application strategy for DCLR in asphalt was proposed, significantly enhancing its resource utilization rate in road engineering. Full article

This study aims to investigate the high-temperature rheological properties and ultraviolet (UV) aging resistance of Buton rock asphalt (BRA) and styrene-butadiene-styrene (SBS) composite modified asphalt. Initially, the surface morphology of BRA and SBS was examined using scanning electron microscopy. The high-temperature rheological properties and chemical characteristics of BRA modified asphalt, SBS modified asphalt, and BRA/SBS composite modified asphalt before and after UV aging were investigated. The results reveal that numerous pores and folds on the surface of BRA form a distinctive honeycomb-like structure that offers a large surface area, enhancing asphalt adsorption and thereby improving the high-temperature properties of asphalt. The addition of SBS enhances the elastic response of Buton rock asphalt modified asphalt (BRAMA). The Fourier transform infrared (FTIR) spectra indicate that BRA effectively reduces the carbonyl and sulfoxide index of asphalt, and the complex modulus aging index (CMAI) and phase angle aging index (PAI) suggest that the BRA/SBS composite modified asphalt exhibits better resistance to ultraviolet aging. Full article

In recent years, asphalt pavement has been subjected to varied environmental conditions during its service life, conditions that predispose it to deformation and cracking. To enhance the performance of asphalt pavement, rock asphalt has been selected as a modifier due to its good compatibility with virgin asphalt binder and its ability to improve the fatigue cracking resistance of asphalt mixtures. Although scholars have conducted some studies on rock asphalt mixtures, research on the fatigue and self-healing performance of these mixtures under conditions such as ultraviolet (UV) aging and freeze–thaw remains limited. This paper presents findings from a study that employs a combined fatigue-healing test to assess the impact of such complex environmental factors on the fatigue and self-healing properties of fine aggregate matrix (FAM) mixtures containing three types of rock asphalts, i.e., Buton, Qingchuan (QC), and Uintaite Modifier (UM). The analysis of fatigue-healing test results, grounded in viscoelastic continuum damage (VECD) theory, indicates that rock asphalt can extend the fatigue life of FAM mixtures, albeit with a concomitant decrease in their self-healing capabilities. The study further reveals that UV aging, freeze–thaw, and UV aging–freeze–thaw conditions all led to a diminution in the fatigue and self-healing properties of FAM mixtures. However, FAM mixtures containing rock asphalt demonstrated greater resilience against these reductions. Atomic force microscope (AFM) results indicate that UV aging reduced the number of bee-structures and enlarged their area, whereas the incorporation of rock asphalt enhanced the uniformity of these structures’ distribution, thereby improving the fatigue cracking resistance of FAM mixtures. Fourier transform infrared spectroscopy (FTIR) analysis reveals that while UV aging increased the carbonyl and sulfoxide indices within the asphalt binder, rock asphalt is effective in mitigating this effect to a certain degree, thereby enhancing the aging resistance of FAM mixtures. Full article

Buton rock asphalt (BRA) has been used in asphalt pavement for its contribution to high-temperature stability. However, how BRA affects the durability of a corresponding asphalt mixture requires systemic discussion. This study investigated how BRA affected durability in terms of the fatigue resistance, thermo-oxidative aging resistance, and long-term moisture stability of asphalt mixture. Furthermore, improvement of the long-term moisture stability of asphalt mixture containing BRA modified asphalt (BRAM) was also included. An AC-20C asphalt mixture based on BRA asphalt, neat asphalt, and SBS-modified asphalt were prepared and their high-temperature, low-temperature, and moisture performance were examined. A semi-circular bending cyclic loading test was used to characterize fatigue performance. Thermo-oxidative aging tests in both the short-term and long-term were used to indicate the aging performance. Freeze–thaw cyclic splitting tests were carried out to investigate BRAM’s long-term moisture stability. Finally, the optimization and enhancement of BRAM’s long-term moisture stability was discussed in terms of ceramic, basalt, and polyester fiber, as well as hydrated lime. Results showed that BRA can enhance the high-temperature, low-temperature, and moisture performance of BRAM. The cracking fatigue resistance and thermo-oxidative aging resistance of BRAM were also improved by BRA. The long-term moisture stability of BRAM was lower than that of the asphalt mixture based on SBS and neat asphalt. It was found that the long-term moisture durability of BRAM can be optimally enhanced by replacing mineral filler with 50% hydrated lime by equal volume and using 0.2wt% ceramic fiber as an additive in BRAM. Full article

The objective of this study is to develop a modified asphalt with excellent rheology and workability. Buton rock asphalt (BRA) composite modified warm mix asphalt (BCMWMA) was prepared, and its rheological properties and micromechanisms were investigated. Initially, warm mix asphalt (WMA) was prepared using 3 wt% Sasobit, and then four BCMWMA samples were prepared by blending 5 wt% to 20 wt% of BRA (with 5 wt% intervals). Subsequently, the microscopic morphology and modification mechanism of BCMWMA were analysed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) tests. Finally, the rheological properties of BCMWMA were examined through conventional properties tests, rotational viscosity tests (RV), dynamic shear rheological tests (DSR) and bending beam rheometer tests (BBR). The results indicate that the BRA and Sasobit composite modifications primarily involve physical modification. BRA improves the high-temperature performance of the modified asphalt but reduces its low-temperature performance. Overall, the BCMWMA exhibits excellent high-temperature performance and workability, contributing to the green and sustainable development of asphalt pavement engineering. Full article

Buton Rock Asphalt (BRA) refers to the natural rock asphalt natively produced on the Buton island of Indonesia. It is often used as a modifier to enhance the performance of asphaltpavement. However, the segregation of BRA in BRA-Modified Asphalt (BRA-MA) has restricted its application. This study aims to investigate how the particle size and content of BRA affect the physical properties and storage stability of BRA-MA. Penetration, softening point, viscosity, and viscosity-temperature susceptibility (VTS) were analyzed. The evaluation method of storage stability was discussed and determined. The segregation of BRA in BRA-MA of static storage and transportation process were simulated and tested. The results suggest that the softening point and viscosity were positively correlated to BRA content and inversely determined by particle size. Penetration, VTS, and ductility were reduced due to the decline in particle size and increment of BRA content. The index of segregation value based on viscosity difference showed better statistical and quantitative significances than the softening-point difference in evaluating the storage stability. The particle size and content of BRA are positively correlated to the segregation of BRA-MA. Both the storage temperature and time were positively correlated to the segregation of BRA-MA. We prove that the relationship between specific surface area and segregation are power functional. BRA-MA with BRA whose 50% particle sizes are lower than 13.6 μm showed low segregation in transportation. Full article

In this paper, two types of Styrene-Butadiene-Rubber (SBR) were adopted to modify the Buton-rock asphalt (BRA) modified asphalt, aiming to select a binder with excellent comprehensive performances. Powder SBR and latex SBR (0%, 2%, 4%, 6%, and 8%), were mixed with the 15 w% BRA modified asphalt. The characterization of rheological properties included dynamic shear rheometer, rotational viscometer, and bending beam rheometer test. The short-term aging performance was characterized by the ratio of the complex shear modulus from the un-aged and rolling thin film oven (RTFOT) -aged asphalt. Besides, Fourier transform infrared spectroscopy and scanning electron microscopy were conducted to reveal the modification mechanism. It was observed that the two kinds of BRA-SBR modified asphalt had preferable anti-crack capacity at low temperatures than the BRA modified asphalt. Compared with latex SBR, the powder SBR significantly improved the high-temperature performance, and the anti-aging capacity was stable. However, some negative influence occurred by the addition of latex SBR on the anti-rutting and short-term aging property. According to the micro-mechanism analysis, adding powder SBR and latex SBR into BRA modified asphalt was a physical blending process, and they improved the dispersion state of BRA in asphalt. Based on the comprehensive performance, the recommended combination was BRA and powder SBR. Full article

To improve the low-temperature performance of the Buton rock asphalt (BRA)-modified asphalt, styrene-butadiene rubber (SBR) was added to it. The BRA-modified asphalt and SBR-BRA composite modified asphalt were prepared by high-speed shearing method. The penetration, softening point, ductility, and Brookfield viscosity of the two kinds of asphalt were measured. The dynamic shear rheometer (DSR) and the beam bending rheometer (BBR) were employed to research the performance of BRA-modified asphalt by adding SBR. The results showed that the pure asphalt in BRA was the main reason to reduce the low-temperature performance of neat asphalt when the content of BRA was 19%. However, the ash in BRA was the main factor to reduce the low-temperature performance when its content was more than 39.8%. When the BRA content was 59.8%, the SBR-BRA composite modified asphalt with SBR contents of 2%, 4%, 6%, and 8%, and it shows that the penetration and ductility of the BRA-modified asphalt are increased by the addition of SBR. The equivalent brittle point was reduced, the stiffness modulus was decreased, and the creep rate was increased. At the same time, the Brookfield viscosity was reduced and the rutting factor was increased. The stiffness modulus of the SBR-BRA composite modified asphalt mixture was increased. That is to say, when SBR was mixed into the BRA-modified asphalt, the low-temperature performance could be remarkably improved based on ensuring high-temperature performance. The low-temperature index of composite modified asphalt was analyzed. It was recommended to apply the equivalent brittle point to evaluate the low-temperature performance of SBR-BRA composite modified asphalt. Full article

As a natural modifier of asphalt, rock asphalt has been widely used to improve its thermal stability and aging resistance. However, the thermal cracking resistance of asphalt modified by rock asphalt is unsatisfactory. In order to improve the thermal cracking resistance in low temperature, two kinds of modifiers—styrene–butadiene rubber (SBR) and nano-CaCO₃—were selected as the compound modifiers, and then implemented to improve the low-temperature performance of the binder. Then, compound asphalt modified by Buton rock asphalt (BRA) was chosen as the study subject. The thermal stability and aging resistance of asphalt modified by BRA, compound-modified asphalt by BRA/SBR, and compound-modified asphalt by BRA and nano-CaCO₃ were determined to identify whether the compound modifiers in the asphalt would have a negative effect on the thermal stability and aging resistance of the asphalt. The dynamic shear rheometer (DSR) test was employed to evaluate the thermal stability. The thin film oven test (TFOT) and pressure aging vessel (PAV) were adopted to determine the aging resistance. The viscoelastic characteristics of asphalt with and without modifiers were revealed to evaluate the low-temperature crack resistance of asphalt modified by compound modifiers. The bending beam rheometer (BBR) creep test was conducted in three test temperatures in order to determine the creep stiffness modulus of the BRA compound-modified asphalt. The viscoelastic model considering the damage caused by loading was established; then, the creep compliance and parameters of the viscoelastic damage model were implemented to evaluate the low-temperature performance of the compound-modified asphalt. The results show that the compound modifiers have little negative effects on the thermal stability and aging resistance of asphalt. The thermal crack resistance of the compound-modified asphalt by BRA/SBR was the best, followed by the compound-modified asphalt by BRA and nano-CaCO₃ within the three materials. The accuracy of forecasting the characteristics of compound-modified asphalt was improved by using the viscoelastic model and considering the damage effect. Full article