8 results on '"Xi, Zhonghua"'
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2. Performance and Morphology of Waterborne Polyurethane Asphalt in the Vicinity of Phase Inversion.
- Author
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Wu, Chengwei, Yang, Haocheng, Cui, Xinpeng, Chen, Yachun, Xi, Zhonghua, Cai, Jun, Zhang, Junsheng, and Xie, Hongfeng
- Subjects
BITUMINOUS materials ,GLASS transition temperature ,POLYURETHANES ,ASPHALT ,TENSILE strength ,THERMAL stability - Abstract
Waterborne polyurethane asphalt emulsion (WPUA) is an environmentally friendly bituminous material, whose performance is highly dependent on the phase structure of the continuous phase. In this paper, WPUAs in the vicinity of phase inversion were prepared using waterborne polyurethane (WPU) and asphalt emulsion. The chemical structures, thermal stability, dynamic mechanical properties, phase-separated morphology and mechanical performance of WPUAs were studied. Fourier-transform infrared (FTIR) spectra revealed that there are no –NCO bonds in either the pure WPU or WPUAs. Moreover, the preparation of WPUA is a physical process. The addition of WPU weakens the thermal stability of asphalt emulsion. WPU improves the storage modulus of asphalt emulsion at lower and higher temperatures. The glass transition temperatures of the WPUA films are higher than that of the pure WPU film. When the WPU concentration increases from 30 wt% to 40 wt%, phase inversion occurs; that is, the continuous phase shifts from asphalt to WPU. The WPUA films have lower tensile strength and toughness than the pure WPU film. However, the elongations at break of the WPUA films are higher than that of the pure WPU film. Both the tensile strength and toughness of the WPUA films increase with the WPU concentration. Due to the occurrence of phase inversion, the elongation at break, tensile strength and toughness of the WPUA film containing 30 wt% WPU are increased by 29%, 250% and 369%, respectively, compared to the film with 40 wt% WPU. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Halogen-free flame retarded cold-mix epoxy asphalt binders: Rheological, thermal and mechanical characterization.
- Author
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Chen, Ru, Gong, Jie, Jiang, Yongjia, Wang, Qingjun, Xi, Zhonghua, and Xie, Hongfeng
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HALOGENS , *EPOXY resins , *ASPHALT , *BINDING agents , *RHEOLOGY , *THERMOPHYSICAL properties , *MECHANICAL behavior of materials - Abstract
Highlights • Halogen-free flame retarded cold-mix epoxy asphalt binder (CEAB) has been developed. • The flame retardancy of the neat CEAB is significantly increased by halogen-free flame retardant. • The addition of halogen-free flame retardants improves the glass transition temperature, thermal stability and tensile strength of the neat CEAB. Abstract Fire safety of asphalt mixtures in highway tunnels has become a problem of great concerns since asphalt and polymer modified asphalt binders are quite flammable and tend to release poisonous gases and smoke while burning. Therefore, flame retardants are incorporated into asphalt binder to improve the fire retardancy of asphalt mixtures. In this paper, aluminum trihydroxide (ATH) and zinc borate (ZB) were used as halogen-free flame retardants to prepare flame retarded cold-mix epoxy asphalt binders (CEABs). The addition of halogen-free flame retardants increased flame retardancy of the neat CEAB. In addition, ATH-ZB retarded CEAB had higher limited oxygen index (LOI) than single ATH and ZB retarded CEABs at the same content. The presence of halogen-free flame retardants increased the viscosity of the neat CEAB. The viscosity of ATH/ZB retarded CEAB was lower than that of ATH retarded CEAB at a specific content. The incorporation of halogen-free flame retardants enhanced the glass transition temperature of the neat CEAB. Thermal stability of the neat CEAB was improved by the halogen-free flame retardants. ATH/ZB retarded CEAB had better thermal stability than ATH retarded CEAB at the same content. The addition of halogen-free flame retardants increased the tensile strength of the neat CEAB. Uniform dispersion of halogen-free flame retardants in CEABs was observed. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
4. Influence of thermal shock on the performance of B-staged epoxy bond coat for orthotropic steel bridge pavements.
- Author
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Xie, Hongfeng, Zhao, Ruikang, Wang, Rui, Xi, Zhonghua, Yuan, Zuanru, Zhang, Junsheng, and Wang, Qingjun
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THERMAL shock , *EPOXY coatings , *ORTHOTROPIC plates , *IRON & steel bridges , *GLASS transition temperature , *BITUMINOUS materials - Abstract
• Thermal shock significantly increases the pull-off strength of the touch-dry BEBC. • The hydrophilic touch-dry BEBC becomes hydrophobic after the thermal shock. • Thermal shock greatly increases the T g of the touch-dry BEBC. • The touch-dry BEBC's tensile strength increases by about 300% after the thermal shock. • Thermal shock temperature has a limited effect on the mechanical properties of BEBCs. B-staged epoxy bond coat (BEBC) has been widely applied as a waterproof adhesive layer in the pavements of orthotropic steel bridges. During its application, the uncured BEBC layer was first paved on the surface of the steel deck or the bituminous surfacing and hot bituminous mixture would be constructed until the BEBC layer became touch-dry. In this paper, the impacts of thermal shock on the degree of cure (DOC), pull-off strength, hydrophilicity, glass transition temperature (T g), damping performance, thermal stability and mechanical behaviors of the touch-dry BEBC were investigated. Thermal shock greatly increased the DOC of the touch-dry BEBC and the touch-dry BEBC turned to be nearly fully cured after the thermal shock at a higher temperature. The pull-off strength of the touch-dry BEBC was remarkably improved by the thermal shock. After the thermal shock at 160 °C, the pull-off strengths at room temperature and at 60 °C of the touch-dry BEBC were increased by 584% and 914%, respectively. After the thermal shock, the contact angle of the touch-dry BEBC was greatly increased and the hydrophilicity of the touch-dry BEBC was converted to hydrophobicity. Thermal shock significantly increased the T g of the touch-dry BEBC. Furthermore, the T g of thermally shocked BEBCs slightly increased in the temperature. Thermal shock improved the damping performance of the fully cured BEBC. The tensile strength and toughness of the touch-dry BEBC were greatly improved by the thermal shock. However, thermal shock lowered the elongation at break of touch-dry BEBC. In the case of thermally shocked BEBCs, the temperature had a limited effect on the tensile strength, while the elongation at break increased in the temperature. The fracture energy first decreased in the temperature and increased after 150 °C. Maximum fracture energy appeared at 160 °C. After the thermal shock, the tensile strength of the touch-dry BEBC was increased by as much as 3-fold. The fracture energy of the BEBC thermally shocked at 160 °C was 182% greater than that of the touch-dry BEBC. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
5. Development of eco-friendly fire-retarded warm-mix epoxy asphalt binders using reactive polymeric flame retardants for road tunnel pavements.
- Author
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Chen, Ru, Zhao, Ruikang, Liu, Ya, Xi, Zhonghua, Cai, Jun, Zhang, Junsheng, Wang, Qingjun, and Xie, Hongfeng
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FIREPROOFING agents , *FIRE resistant polymers , *TUNNELS , *EPOXY resins , *ASPHALT , *GLASS transition temperature , *PAVEMENTS - Abstract
[Display omitted] • Eco-friendly fire-retarded warm-mix epoxy asphalt binders (WEABs) have been developed. • RPFR of significantly improved the fire retardancy of the pure WEAB. • RPFR hinders WEAB's cure reaction and extends the allowable construction time of WEAB mixtures. • RPFR improves the glass transition temperature and thermal stability of the pure WEAB. • Double phase separation forms in RPFR modified WEABs. Epoxy asphalt binder is flammable and plenty of fumes are produced during its high-temperature pavements in tunnels. To improve fire retardancy and reduce asphalt fumes, eco-friendly flame-retarded warm-mix epoxy asphalt binders (WEABs) for road tunnel pavements were developed by incorporation of reactive polymeric flame retardant (RPFR), which was composed of a reactive polymeric brominated epoxy oligomer (BEO) and antimony oxide. The influence of RPRF on flame retardancy, rotational viscosity, microstructures, thermal properties and mechanical performance of the pure WEAB was investigated using various techniques: oxygen index instrument, Brookfield viscometer, confocal microscope, differential scanning calorimeter, thermogravimetric analyzer and universal testing machine. The presence of RPFR significantly improved the limited oxygen index (LOI) of the pure WEAB. The LOI of RPFR modified WEABs increased in the flame retardant loading. The reaction of epoxide groups of RPFR with the curing agents of epoxy asphalt reduced the viscosity of the pure WEAB and extended the allowable construction time of the WEAB mixture. The inclusion of RPFR increased the glass transition temperature (T g) of the pure WEAB. For modified WEABs, the T g increased in the RPFR loading. RPFR reacted into the epoxy asphalt backbone through the reaction between epoxy groups and curing agents. The incorporation of RPFR improved the thermal stability of the pure WEAB. The addition of 8 wt% RPFR increased the tensile strength of the pure WEAB, while the inclusion of RPFR slightly decreased the break elongation of the pure WEAB. Double phase separation occurred in RPFR modified WEAB: the main phase separation included the continuous epoxy phase and the discontinuous asphalt domains, in which the secondary phase separation formed with asphalt as the continuous phase and spherical BEO domains as the discontinuous phase. The particle size of BEO domains decreased with the increase of the RPFR loading. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
6. Laboratory investigation on the microstructure and performance of SBS modified epoxy asphalt binder.
- Author
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Zhang, Jing, Su, Wufeng, Liu, Ya, Gong, Jie, Xi, Zhonghua, Zhang, Junsheng, Wang, Qingjun, and Xie, Hongfeng
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ASPHALT modifiers , *ASPHALT , *GLASS transition temperature , *EPOXY resins , *PHASE separation , *MICROSTRUCTURE - Abstract
• Phase separation of ESBA disrupts the original dispersion of SBS in the asphalt. • The size of SBS domains in ESBAs increases in the SBS loading. • ESBA's viscosity increases in the SBS loading. • The thermal stability of ESBAs enhances with the increase of SBS loading. • The neat EA's elongation at break increases by 56% with the addition of 3 wt% SBS. Both styrene–butadiene-styrene copolymer (SBS) and epoxy resin have been widely applied in the asphalt modification. The influence of SBS concentration on the morphology, viscosity, thermal stability, glass transition temperature (T g), damping performance and mechanical behaviors of the neat EA binder was studied. Double phase separation occurred in the epoxy SBS modified asphalt (ESBA): main phase separation between epoxy and the SBS modified asphalt (SBA) and secondary phase separation between asphalt and SBS. The occurrence of phase separation in the ESBA disrupted the original dispersion of SBS particles in SBA and resulted in the redistribution of SBS in the form of smaller spherical particles. The inclusion of SBS increased the viscosity of the neat EA. Furthermore, the viscosity of ESBAs increased with the SBS content. ESBAs had as long as 150-min construction time for the mixture pavement. The presence of SBS improved the thermostability of the neat EA. In terms of ESBAs, the thermostability increased with the SBS content. The addition of SBS lowered the T g of the neat EA when the SBS content was lower than 4 wt%. The T g of ESBAs increased with the SBS content. The incorporation of SBS significantly enhanced the damping behaviors of the neat EA. The tensile strength of the neat EA was improved with the addition of 2 wt% SBS. The inclusion of SBS improved the elongation at break and the toughness of the neat EA when the SBS loading was greater than 1 wt%. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
7. Toughening epoxy asphalt binder using core-shell rubber nanoparticles.
- Author
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Su, Wufeng, Han, Xiaocheng, Gong, Jie, Xi, Zhonghua, Zhang, Junsheng, Wang, Qingjun, and Xie, Hongfeng
- Subjects
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GLASS transition temperature , *EPOXY resins , *ASPHALT , *NANOPARTICLES , *DISCONTINUOUS precipitation - Abstract
• Core-shell rubber (CSR) nanoparticle toughened epoxy asphalt (EA) has been developed. • The toughness of the pure EA increases by 2-fold with only addition of 1 wt% CSR. • The shell of CSR is broken and the core of CSR swells in the EA. • Newly micro-scale CSR phase uniformly disperses in the epoxy phase of the EA. • CSR nanoparticles alters the mechanism of phase separation of the pure EA. Core-shell rubber (CSR) has been widely applied in the improvement of the toughness for the brittle epoxy resin. In this study, an epoxy asphalt (EA) binder has been toughened by the inclusion of CSR nanoparticles with approximately 100–200 nm in diameter. The incorporation of CSR nanoparticles significantly increased the viscosity of the pure EA during curing. Even with 5 wt% CSR, the EA blend exhibited extremely long operational lifetime (more than 2.5 h) for mixture pavements. The glassy shell of CSR nanoparticles was broken and the rubbery core of CSR nanoparticles swelled in the EA. New micro-scale CSR domains formed and uniformly dispersed in the epoxy phase of the cured EA. The inclusion of CSR nanoparticles altered the phase separation mechanism of the pure EA. The sea-island morphology of the pure EA took place through the nucleation and growth (NG) mechanism, while co-continuous microstructures in the EA blends with 3 wt% and 5 wt% CSR formed through the spinodal decomposition (SD) mechanism. Both sea-island and co-continuous microstructures via combined the NG and SD mechanisms were observed in the EA blend containing 1 wt% CSR. The glass transition temperature and thermal stability of the pure EA was improved by the inclusion of higher CSR loadings. The incorporation of CSR greatly enhanced the mechanical properties of the pure EA. In the case of 1 wt% CSR inclusion, 29% increase in the tensile strength, 60% improvement in the elongation at break and 2-fold increment in the toughness were obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
8. Impact of waste cooking oil on the viscosity, microstructure and mechanical performance of warm-mix epoxy asphalt binder.
- Author
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Li, Chenxuan, Han, Xiaocheng, Gong, Jie, Su, Wufeng, Xi, Zhonghua, Zhang, Junsheng, Wang, Qingjun, and Xie, Hongfeng
- Subjects
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PETROLEUM waste , *VISCOSITY , *ASPHALT , *EPOXY resins , *MICROSTRUCTURE - Abstract
• Waste cooking oil (WCO) modified epoxy asphalt binder (EAB) has been developed. • WCO lowers the viscosity and thus extends the construction time of the neat EAB. • Phase inversion in WEAB occurs when 6 wt% WCO is added. • WCO improves the low-temperature performance of the neat EAB. • WCO enhances the damping properties and thermal stability of the neat EAB. Waste cooking oil (WCO) was used as a warm mix asphalt (WMA) additive to modify warm-mix asphalt binder (WEAB) with the expectation of lowering the viscosity and prolonging the construction time of the binder. The viscosity, phase separation, viscoelasticity, thermostability and mechanical properties of WCO modified WEABs were studied and compared with the neat WEAB. WCO significantly reduced the WEAB's viscosity and extended the construction time of the neat WEAB. Moreover, the reducing and prolonging effects increased with the WCO content. Phase-inverted microstructure and secondary phase separation formed in the modified WEAB with 6 wt% WCO. The inclusion of WCO improved the low-temperature performance of the neat WEAB. The damping behavior and thermostability of the neat WEAB were improved with the inclusion of WCO. The presence of WCO increased the elongation at break of the neat WEAB when the waste oil content was lower than 4 wt%. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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