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Sheng Li

Bio: Sheng Li is an academic researcher from Changsha University of Science and Technology. The author has contributed to research in topics: Asphalt & Materials science. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Papers
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TL;DR: In this paper, the natural rubber additive (NRA) was recommended as a modifier in the preparation of high viscosity asphalt (HVA) binder, and the proposed HVAM with the NRA modifier has a superior performance to other conventional mixtures in the temperature susceptibility and resistance to moisture damage.
Abstract: The property of asphalt binder plays an important role in the performance of asphalt mixture. The natural rubber additive (NRA) was recommended as a modifier in the preparation of high viscosity asphalt (HVA) binder. Then, the gradation named LASTIKA-13 was adopted to design the high viscosity asphalt mixture (HVAM) according to the orthogonal test analysis and the optimized gradation. The performance of the proposed HVAM was evaluated through a series tests including the permanent deformation at high temperature, moisture stability, low-temperature cracks, and bending fatigue test. The results indicate that the proposed modified asphalt binder shows a comparable property with the conventional modified asphalt binder. The proposed HVAM with the NRA modifier has a superior performance to other conventional mixtures in the temperature susceptibility and resistance to moisture damage. Furthermore, the proposed HVAM was less sensitive to the temperature change and has good performance in terms of resistance to low-temperature cracks, bonding characteristics, and fatigue behaviors.

4 citations

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TL;DR: Results show that corrosion sensitivity of the quenching-aged alloy is much higher than that of the double-aged (DA) alloy, and the corrosion resistance of theQuenched alloy decreases firstly and then increases, while the self-corrosion potential and self-current density is high.
Abstract: The quenching condition of aluminum alloy can affect the mechanical property and corrosion resistance of the profile. This paper is aimed at the low quench sensitivity of aluminum alloys. Scanning electron microscopy and transmission electron microscopy were used to analyze precipitate behaviors of the 7A46 aluminum alloy under different isothermal cooling conditions and microstructure evolutions of quench-induced precipitations. The effect of the different isothermal time on the corrosion resistance of the alloy, and the relationship between microstructure and corrosion resistance after quenching were revealed through electrochemical impedance spectroscopy and potentiodynamic polarization tests. Results show that corrosion sensitivity of the quenching-aged alloy is much higher than that of the double-aged (DA) alloy, and the corrosion resistance of the quenched alloy decreases firstly and then increases. Due to the high density of the matrix precipitates, the increased content of the impurity element, the discontinuity of the grain boundary precipitates and the widening of the precipitates free zone, the most serious degree of corrosion performance among the quenched alloys is 295 °C at 800 s, and the self-corrosion potential and self-current density is −0.919 V and 2.371 μA/cm2, respectively.

1 citations

Journal ArticleDOI
TL;DR: Based on thermal-mechanical coupling simulation analysis and physical engineering tracking observation, the mechanical behavior and response of a continuously reinforced concrete and asphalt concrete composite pavement layer were analyzed, and the causes of cracking on the surface and bottom of the asphalt layer were revealed as discussed by the authors .
Abstract: Based on thermal–mechanical coupling simulation analysis and physical engineering tracking observation, the mechanical behavior and response of a continuously reinforced concrete and asphalt concrete (CRC + AC) composite pavement layer were analyzed, and the causes of cracking on the surface and bottom of the asphalt layer were revealed. Studies have shown that under normal driving conditions, the AC layer, which is usually in the position of the wheel load gap and wheel load side, more easily generates a longitudinal “corresponding crack”. Compared to normal driving, longitudinal cracks are generated more easily inside of the curve, and transverse cracks occur more easily on poor stadia curves. When the AC layer thickness is less than 8 cm, the AC layer is more prone to bottom-up cracking, and it is more prone to top-down cracking when it is more than 8 cm thick. Comprehensively considering the tensile stress, shear stress, and the thickness of the AC layer, it is recommended that the suitable thickness range of the AC layer is 8 cm~14 cm. The calculated results show good agreement with the physical engineering investigation. The research results can provide a theoretical and scientific basis for cracking control and the rational design of a CRC + AC composite pavement layer.

1 citations

Journal ArticleDOI
TL;DR: In this paper , nonmetallic fractions (NMFs) from waste printed circuit boards (PCBs) are ground into powder and added into matrix asphalt to produce PCB-NMF-modified asphalt.
Abstract: Non-metallic fractions (NMFs) from waste printed circuit boards (PCBs) are mostly composed of cured resin and fiber. In this study, NMF material from a PCB was ground into powder and added into matrix asphalt to produce PCB-NMF-modified asphalt. To improve the compatibility of PCB-NMF and asphalt, a compatibilizer consisting of tung oil and glycerol was also developed. The optimum compatibilizer content was determined to be 8% by weight of the PCB-NMF through a series of laboratory tests, including the softening point, penetration, ductility, and softening point difference (SPD). The micro-mechanism of NMF powder-modified asphalt was analyzed through Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope test (SEM). The performances of PCB-NMF-modified asphalt were evaluated by the dynamic shear rheology (DSR) test and the low-temperature bending beam rheometer (BBR) test. The optimum compatibilizer content was 8% by weight of the NMF powder and the optimum content of NMF powder was determined to be 30% by weight of the asphalt based on a comprehensive evaluation. The results show that PCB-NMF can significantly improve stiffness, rutting resistance, high-temperature stability, and temperature sensitivity of asphalt material at an appropriate content. The BBR tests revealed that PCB-NMF slightly weakened the cracking resistance of asphalt at low temperatures. The SEM test showed that the addition of a compatibilizer can increase the compatibility by making the NMF powder evenly dispersed. The FTIR test results implied that a chemical reaction may not have happened between PCB-NMF, compatibilizer, and the matrix asphalt. Overall, it is a promising and sustainable way to utilize PCB-NMF as a modifier for asphalt material and reduce electronic waste treatment at a low cost.

Cited by
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TL;DR: In this paper , a comprehensive testing program was employed to investigate the effect of 100 % aggregate replacement on the composites' mechanical performance, water absorption, impact resistance, thermal conductivity, resistance to harsh environments, and microstructural changes.

3 citations

Journal ArticleDOI
TL;DR: In this paper, the high-viscosity asphalt which is added to nanometer CaCO3 will improve its conventional performance indicators is put forward, and the PG level will reach SBS level, and low temperature performance is better than SBS.
Abstract: The high-viscosity asphalt has the characteristics of high viscosity, low penetration and high softening point. Its mixture is superior in high temperature stability and water stability, but slightly worse in the low temperature cracking resistance.In this article, the natural rubber asphalt which is named Superflex in Indonesia would be used as modifier to make the high-viscosity asphalt. Then four kinds of zero dimensional nanometer CaCO3 were chosen to carry out the compound modification and test the penetration and other basic indicators of different compound modified asphalt, and the better performances of the C type nanometer CaCO3compound modified asphalt would have been achieved in PG grade test. From the result of the test, the conclusion that the high viscosity asphalt which is added to nanometer CaCO3 will improve its conventional performance indicators is put forward, and the PG level will reach SBS level, and the low temperature performance is better than SBS.

3 citations

Journal ArticleDOI
TL;DR: In this paper , a mathematical model was developed for the dynamic modulus master curve unifying these factors by means of horizontal shifting due to the time-temperature superposition principle and the vertical shift factor as a function of reduced frequency and compactness.
Abstract: The dynamic modulus is a key property determining the short- and long-term performance of asphalt pavement, and its strong dependence on confining pressure and material density (mixture compactness) has been clearly indicated in the literature. It is always challenging to reproduce three-dimensional in situ stress conditions in the laboratory. To alleviate this difficulty, in this study, a convenient experimental setup was developed, in which the lateral confinement was made present and variable as a concomitant reaction of the surrounding materials to the vertical loading. Three dense-graded mixtures were prepared to a set of four different densities and then subjected to the confined dynamic modulus test. The results indicated a significant dependence of the confined modulus on the three factors of temperature, frequency, and compactness and that the mixture with coarser gradation demonstrated a less sensitivity to these parameters. A mathematical model was developed for the dynamic modulus master curve unifying these factors by means of horizontal shifting due to the time–temperature superposition principle (validated against the variable confinement at different compactness) and the vertical shift factor as a function of reduced frequency and compactness. The adequacy of the model was demonstrated using the experimental data, and its potential application in field pavement compaction was discussed.

1 citations

Journal ArticleDOI
TL;DR: In this paper , the authors studied the technology of liquid CO2 phase-transition fracturing in a coal seam, and the field test was carried out in the 81506th working face of the Baode Coal Mine.
Abstract: The geological structures of the coal fields in China are complex. With a continuous increase in the mining depth, the coal seams show the characteristics of high gas and low permeability, and the disaster potential for a coal and gas outburst intensifies in the process of coal mining. Gas drainage is one of the primary measures used to prevent and control gas disasters. Effectively improving the permeability of a coal seam requires urgent attention. Currently, the method of loose blasting is used in engineering to enhance the permeability of coal seams. However, the technology of loose blasting easily leads to the poor development of coal fractures or the severe crushing of coal, which will affect the gas drainage. Thus, this paper studied the technology of liquid CO2 phase-transition fracturing in a coal seam. COMSOL was used to determine the influence radius of the liquid carbon-dioxide phase-transition cracking, which was 13.4 m, and to design the scheme of the borehole. The field test was carried out in the 81506th working face of the Baode Coal Mine. From the onsite-monitoring data, the results showed that the drainage effect increased by 293.9%, the gas-drainage concentration increased by 242.4%, the permeability coefficient of the coal seam increased by 3–7.75 times, and the permeability enhancement effect was good.
Journal ArticleDOI
10 Nov 2022-Energies
TL;DR: In this paper , the properties of as-quenched AA7075-T6 are predicted within the framework of quench factor analysis (QFA), using cooling curves obtained from a quench test.
Abstract: Quenching affects the mechanical and corrosion properties of precipitation-hardenable alloys such as aluminum alloy 7075-T6 (AA7075-T6). In this paper, the properties of as-quenched AA7075-T6 are predicted within the framework of quench factor analysis (QFA), using cooling curves obtained from a quench test. Theoretical and computational approaches are used to predict spatial and temporal variations of temperature. The temperature variations are used to predict the quench factor and consequently the material properties. A test is carried out on a block of AA7075-T6 quenched partly in water and partly in air followed by hardness measurements and electrochemical characterizations. The results show that the hardness and the corrosion potential of the quenched block decrease as the cooling rate decreases. The results further suggest the existence of a corrosion product layer for the water-quenched part of the sample. This was not observed for the air-cooled part. A new corrosion prediction model is developed by using the QFA method, cyclic polarization, and electrochemical impedance spectroscopy test results. The present model may be used to potentially reduce the number of corrosion tests in evaluating corrosion properties of quenched AA7075-T6. Model predictions for corrosion and hardness are in good agreement with experimental results.