Steam-cured condition is found to cause larger porosity and worse properties of concrete compared with normal curing condition. For the sake of seeking effective measurements to eliminate this bad effect of steam-cure...Steam-cured condition is found to cause larger porosity and worse properties of concrete compared with normal curing condition. For the sake of seeking effective measurements to eliminate this bad effect of steam-cured condition on concrete, the water sorptivity and pore structure of steam-cured concretes exposed to different subsequent curing conditions were investigated after steam-curing treatment. The capillary absorption coefficient and porosity of the corresponding concretes were analyzed, and their mechanisms were also discussed. The results indicate that water sorptivity and pore structure of steam-cured concrete are greatly influenced by the curing condition used in subsequent ages. Exposure steam-cured concrete to air condition has an obviously bad effect on its properties and microstructures. Adopting subsequent curing of immersing steam-cured concrete into about 20℃ water after steam curing period can significantly decrease its capillary absorption coefficient and porosity. Steam-cured concrete with 7 d water curing has minimum capillary absorption coefficient and total porosity. Its water sorptivity is decreased by 23% compared with standard curing concrete and the porosity is 9.6% lower. Moreover, the corresponding gradient of water sorptivity and porosity of steam-cured concrete both decrease, thus mictostructure of concrete becomes more homogeneous.展开更多
The vibration pretreatment-microwave curing process is an efficient,low energy consumption,and high-quality out-of-autoclave curing process for carbon fiber resin matrix composites.This study aims to investigate the i...The vibration pretreatment-microwave curing process is an efficient,low energy consumption,and high-quality out-of-autoclave curing process for carbon fiber resin matrix composites.This study aims to investigate the impact of vibration pretreatment temperature on the fiber weight content,microscopic morphology and mechanical properties of the composite laminates by using optical digital microscopy,universal tensile testing machine and thermo-gravimetric analyzer.Additionally,the combined mode of Bragg fiber grating sensor and temperature measurement fiber was employed to explore the effect of vibration pretreatment on the strain process during microwave curing.The study results revealed that the change in vibration pretreatment temperature had a slight impact on the fiber weight content when the vibration acceleration remained constant.The metallographic and interlaminar strength of the specimen formed at a vibration pretreatment temperature of 80℃ demonstrated a porosity of 0.414% and a 10.69% decrease in interlaminar shear strength compared to autoclave curing.Moreover,the introduction of the vibration energy field during the microwave curing process led to a significant reduction in residual strain in both the 0°and 90°fiber directions,when the laminate was cooled to 60℃.展开更多
In this manuscript,the neat epoxy(EP)and functionalized Fe_(3)O_(4)(G-Fe_(3)O_(4))reinforced epoxy(G-Fe_(3)O_(4)/EP)coatings were cured under different temperatures,and the effect of the low curing temperature on the ...In this manuscript,the neat epoxy(EP)and functionalized Fe_(3)O_(4)(G-Fe_(3)O_(4))reinforced epoxy(G-Fe_(3)O_(4)/EP)coatings were cured under different temperatures,and the effect of the low curing temperature on the anticorrosion performance was investigated.The experimental results show that the epoxy-amine ring-open addition reaction mainly exists in the curing process,and the activation energies of the reaction for the two coatings are 55.84 and 53.29 kJ/mol,respectively.For the coatings cured at the low temperature,almost no pores could be detected on the fracture surface,but the presentence of the rough regions reflects the poor curing state.As compared with the samples cured at the high temperature,the anticorrosion performance of the coatings with the low curing temperature is worse,and the decrease rate of the anticorrosion performance is slower,because of the poor curing state and low adhesion obtained at the low temperature.展开更多
Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepare...Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepared using different catalyst amounts(denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing.An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs;these factors can be feasibly controlled using an appropriate catalyst amount.展开更多
为实现工业固废在道路与铁道路基工程中的高值化利用,助力双碳目标在交通运输工程领域中的达成,采用钢渣、矿渣与2种脱硫产物(DP-1、DP-2)等工业固废制备再生胶凝固化剂。基于响应面法考察不同工业固废的交互作用并得到其最优组配。采...为实现工业固废在道路与铁道路基工程中的高值化利用,助力双碳目标在交通运输工程领域中的达成,采用钢渣、矿渣与2种脱硫产物(DP-1、DP-2)等工业固废制备再生胶凝固化剂。基于响应面法考察不同工业固废的交互作用并得到其最优组配。采用最优组配下的固化剂对粉土进行改良固化,并表征本研究固化粉土微观结构。与水泥固化粉土作对比,探究了固化剂掺量、养护龄期对固化粉土力学性能和耐久性的影响规律,并分析2种固化粉土的矿物成分,探究再生胶凝固化剂的粉土固化机理。研究结果表明:7 d无侧限抗压强度(p_(usc))响应面模型经残差正态概率分布检验,模型可靠度较高。钢渣与矿渣、钢渣与DP-2交互作用对7 d p_(usc)值的影响极其显著,再生胶凝固化剂最优配比(%)为钢渣∶矿渣∶DP-1∶DP-2=52.1∶19.9∶19.5∶8.5。研究可知,固化粉土具有良好的力学性能和耐久性,在养护后期(28 d)与水泥固化粉土p_(usc)值、加州承载比值、水稳性能系数值、冻融循环系数值分别相差1.9%、0.5%、1.0%、2.3%。再生胶凝固化剂组分在碱性环境中发挥协同作用,水化产物交错生长填充了粉土颗粒之间的孔隙,从而提高了固化粉土的力学性能。同掺量的再生胶凝固化剂碳排放仅为水泥的1.66%,推荐再生胶凝固化剂路床固化工程最优掺量为6%~8%,该技术的推广应用具有重要环保和社会意义。展开更多
基金Project(2008G031-18) supported by the Ministry of Railway Science and Technology Research Foundation of ChinaProject(2010R50034) supported by the Key Science and Technology Innovation Team Program of Zhejiang Province, ChinaProject(2010QZZD018) supported by Leading-edge Research Program of Central South University,China
文摘Steam-cured condition is found to cause larger porosity and worse properties of concrete compared with normal curing condition. For the sake of seeking effective measurements to eliminate this bad effect of steam-cured condition on concrete, the water sorptivity and pore structure of steam-cured concretes exposed to different subsequent curing conditions were investigated after steam-curing treatment. The capillary absorption coefficient and porosity of the corresponding concretes were analyzed, and their mechanisms were also discussed. The results indicate that water sorptivity and pore structure of steam-cured concrete are greatly influenced by the curing condition used in subsequent ages. Exposure steam-cured concrete to air condition has an obviously bad effect on its properties and microstructures. Adopting subsequent curing of immersing steam-cured concrete into about 20℃ water after steam curing period can significantly decrease its capillary absorption coefficient and porosity. Steam-cured concrete with 7 d water curing has minimum capillary absorption coefficient and total porosity. Its water sorptivity is decreased by 23% compared with standard curing concrete and the porosity is 9.6% lower. Moreover, the corresponding gradient of water sorptivity and porosity of steam-cured concrete both decrease, thus mictostructure of concrete becomes more homogeneous.
基金Projects(52175373,52005516)supported by the National Natural Science Foundation of ChinaProject(2018YFA0702800)supported by the National Key Basic Research Program,ChinaProject(ZZYJKT2021-03)supported by the State Key Laboratory of High Performance Complex Manufacturing,Central South University,China。
文摘The vibration pretreatment-microwave curing process is an efficient,low energy consumption,and high-quality out-of-autoclave curing process for carbon fiber resin matrix composites.This study aims to investigate the impact of vibration pretreatment temperature on the fiber weight content,microscopic morphology and mechanical properties of the composite laminates by using optical digital microscopy,universal tensile testing machine and thermo-gravimetric analyzer.Additionally,the combined mode of Bragg fiber grating sensor and temperature measurement fiber was employed to explore the effect of vibration pretreatment on the strain process during microwave curing.The study results revealed that the change in vibration pretreatment temperature had a slight impact on the fiber weight content when the vibration acceleration remained constant.The metallographic and interlaminar strength of the specimen formed at a vibration pretreatment temperature of 80℃ demonstrated a porosity of 0.414% and a 10.69% decrease in interlaminar shear strength compared to autoclave curing.Moreover,the introduction of the vibration energy field during the microwave curing process led to a significant reduction in residual strain in both the 0°and 90°fiber directions,when the laminate was cooled to 60℃.
基金Project(U2106216)supported by the National Natural Science Foundation of China。
文摘In this manuscript,the neat epoxy(EP)and functionalized Fe_(3)O_(4)(G-Fe_(3)O_(4))reinforced epoxy(G-Fe_(3)O_(4)/EP)coatings were cured under different temperatures,and the effect of the low curing temperature on the anticorrosion performance was investigated.The experimental results show that the epoxy-amine ring-open addition reaction mainly exists in the curing process,and the activation energies of the reaction for the two coatings are 55.84 and 53.29 kJ/mol,respectively.For the coatings cured at the low temperature,almost no pores could be detected on the fracture surface,but the presentence of the rough regions reflects the poor curing state.As compared with the samples cured at the high temperature,the anticorrosion performance of the coatings with the low curing temperature is worse,and the decrease rate of the anticorrosion performance is slower,because of the poor curing state and low adhesion obtained at the low temperature.
基金supported by Wuxi HIT New Material Research Institute and China Academy of Engineering Physics。
文摘Herein, the effect of fluoropolymer binders on the properties of polymer-bonded explosives(PBXs) was comprehensively investigated. To this end, fluorinated semi-interpenetrating polymer networks(semiIPNs) were prepared using different catalyst amounts(denoted as F23-CLF-30-D). The involved curing and phase separation processes were monitored using Fourier-transform infrared spectroscopy, differential scanning calorimetry, a haze meter and a rheometer. Curing rate constant and activation energy were calculated using a theoretical model and numerical method, respectively. Results revealed that owing to its co-continuous micro-phase separation structure, the F23-CLF-30-D3 semi-IPN exhibited considerably higher tensile strength and elongation at break than pure fluororubber F2314 and the F23-CLF-30-D0 semi-IPN because the phase separation and curing rates matched in the initial stage of curing.An arc Brazilian test revealed that F23-CLF-30-D-based composites used as mock materials for PBXs exhibited excellent mechanical performance and storage stability. Thus, the matched curing and phase separation rates play a crucial role during the fabrication of high-performance semi-IPNs;these factors can be feasibly controlled using an appropriate catalyst amount.
文摘为实现工业固废在道路与铁道路基工程中的高值化利用,助力双碳目标在交通运输工程领域中的达成,采用钢渣、矿渣与2种脱硫产物(DP-1、DP-2)等工业固废制备再生胶凝固化剂。基于响应面法考察不同工业固废的交互作用并得到其最优组配。采用最优组配下的固化剂对粉土进行改良固化,并表征本研究固化粉土微观结构。与水泥固化粉土作对比,探究了固化剂掺量、养护龄期对固化粉土力学性能和耐久性的影响规律,并分析2种固化粉土的矿物成分,探究再生胶凝固化剂的粉土固化机理。研究结果表明:7 d无侧限抗压强度(p_(usc))响应面模型经残差正态概率分布检验,模型可靠度较高。钢渣与矿渣、钢渣与DP-2交互作用对7 d p_(usc)值的影响极其显著,再生胶凝固化剂最优配比(%)为钢渣∶矿渣∶DP-1∶DP-2=52.1∶19.9∶19.5∶8.5。研究可知,固化粉土具有良好的力学性能和耐久性,在养护后期(28 d)与水泥固化粉土p_(usc)值、加州承载比值、水稳性能系数值、冻融循环系数值分别相差1.9%、0.5%、1.0%、2.3%。再生胶凝固化剂组分在碱性环境中发挥协同作用,水化产物交错生长填充了粉土颗粒之间的孔隙,从而提高了固化粉土的力学性能。同掺量的再生胶凝固化剂碳排放仅为水泥的1.66%,推荐再生胶凝固化剂路床固化工程最优掺量为6%~8%,该技术的推广应用具有重要环保和社会意义。
