Precast concrete pavements(PCPs)represent an innovative solution in the construction industry,addressing the need for rapid,intelligent,and low-carbon pavement technologies that significantly reduce construction time ...Precast concrete pavements(PCPs)represent an innovative solution in the construction industry,addressing the need for rapid,intelligent,and low-carbon pavement technologies that significantly reduce construction time and environmental impact.However,the integration of prefabricated technology in pavement surface and base layers lacks systematic classification and understanding.This paper aims to fill this gap by introducing a detailed analysis of discretization and assembly connection technology for cement concrete pavement(CCP)structures.Through a comprehensive review of domestic and international literature,the study classifies prefabricated pavement technology based on discrete assembly structural layers and presents specific conclusions(i)surface layer discrete units are categorized into bottom plates,top plates,plate-rod separated assemblies,and prestressed connections,with optimal material compositions identified to enhance mechanical properties;(ii)base layer discrete units include block-type,plate-type,and beam-type elements,highlighting their contributions to sustainability by incorporating recycled materials(iii)planar assembly connection types are assessed,ranking them by load transfer efficiency,with specific dimensions provided for optimal performance;and(iv)vertical assembly connections are defined by their leveling and sealing layers,suitable for both new constructions and repairs of existing roads.The insights gained from this review not only clarify the distinctions between various structural layers but also provide practical guidelines for enhancing the design and implementation of PCP.This work contributes to advancing sustainable and resilient road construction practices,making it a significant reference for researchers and practitioners in the field.展开更多
Flexible electrochemical capacitors（ECs） are vitally important as the emerging flexible electronics.We have prepared polypyrrole doped with counter ion of Cl-on carbon fibers（PPy-Cl/CFs） via the simple electrochem...Flexible electrochemical capacitors（ECs） are vitally important as the emerging flexible electronics.We have prepared polypyrrole doped with counter ion of Cl-on carbon fibers（PPy-Cl/CFs） via the simple electrochemical deposition method.The flexible ECs based on PPy-Cl/CFs electrodes have been assembled by using H_3PO_4/poly（vinyl alcohol）（PVA）,H_2SO_4/PVA,LiClO_4/PVA,KCl/PVA and Li Cl/PVA as gel electrolytes.The capacitive properties of ECs have been systematically evaluated with electrochemical methods.The results show that the cells with H_3PO_4/PVA electrolyte exhibit good cyclic stability（91.5% retention after 15000 cycles） although PPy-Cl/CFs has moderate specific capacitance in H_3PO_4/PVA（41.6 m F·cm^-1 or 52.0 F·cm^-3）.However,the ECs in other electrolytes have poor cyclic stability.Further electrochemical analysis reveals that the doping/dedoping processes of PPy-Cl/CFs are different in the five electrolytes,and X-ray photoelectron spectra demonstrate that the ratios of counter anions in PPy＇s oxidized states to those in reduced states are obviously different when PPy-Cl/CFs are kept in reduced or oxidized states in the five electrolytes.The results also illustrate why the capacitors using H_3PO_4/PVA as electrolyte exhibit good cyclic stability.Furthermore,a light emitting diode（LED） with a threshold voltage of 2.5 V can be lighted by three ECs connected in series.展开更多
Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This...Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This paper presents a new type of assembled connection joint for the high-rise modularized construction. Cyclic shear tests of full-scale joints were carried out, and the key indexes of their seismic performances including the hysteretic performance, ductility, and energy dissipation capacity were analyzed and obtained. The results show that the hysteresis loops of longitudinal and lateral cyclic shear tests were both plump in shapes. The ductility coefficients were 4.54 and 4.98, and the energy dissipation coefficients were 1.83 and 1.43, respectively. The test joint had good ductility and energy dissipation capacity. The positions of yield failure of specimens were mainly concentrated in the connection areas between the column and short beam or end-plate. The research can provide the technical reference for the seismic design and engineering application of related modularized constructions.展开更多
Prefabricated pavement is increasingly applied worldwide due to the rapid construction on-site.This paper presents a state-of-the-art review of the precast systems and assembly connection of concrete slabs,as well as ...Prefabricated pavement is increasingly applied worldwide due to the rapid construction on-site.This paper presents a state-of-the-art review of the precast systems and assembly connection of concrete slabs,as well as the precast pavement features.The previous research indicates that:(1)both super-slab and Michigan systems are recommended with the satisfied road performance close to the cast-in-place;(2)flexible base material is suggested for the fabricated pavement for the satisfied leveling and stress distribution;(3)to prevent the voiding phenomenon of the fabricated pavement,the sand cushion course,dry mixed mortar or self-leveling mortar,and other flowable materials could be used for the secondary leveling of the base after the pavement splicing;(4)two-direction dowel bars are recommended for slab connections of the fabricated pavement,which helps to improve the load transfer capacity of the joints and enhance the durability of the fabricated pavement structure;(5)the sealing treatment of precast slab joints needs strengthening to reduce the impact of surface runoff on the base course;(6)the further research focuses are designing with functional,composite,mechanized,intelligent,lightweight,and flexible pavement slabs.Besides,pavement mechanical properties induced by temperature overlapping traffic loads need to be revealed.展开更多
基金supported by the Research Program of Wuhan Building Energy Efficiency Office(grant number 202331).
文摘Precast concrete pavements(PCPs)represent an innovative solution in the construction industry,addressing the need for rapid,intelligent,and low-carbon pavement technologies that significantly reduce construction time and environmental impact.However,the integration of prefabricated technology in pavement surface and base layers lacks systematic classification and understanding.This paper aims to fill this gap by introducing a detailed analysis of discretization and assembly connection technology for cement concrete pavement(CCP)structures.Through a comprehensive review of domestic and international literature,the study classifies prefabricated pavement technology based on discrete assembly structural layers and presents specific conclusions(i)surface layer discrete units are categorized into bottom plates,top plates,plate-rod separated assemblies,and prestressed connections,with optimal material compositions identified to enhance mechanical properties;(ii)base layer discrete units include block-type,plate-type,and beam-type elements,highlighting their contributions to sustainability by incorporating recycled materials(iii)planar assembly connection types are assessed,ranking them by load transfer efficiency,with specific dimensions provided for optimal performance;and(iv)vertical assembly connections are defined by their leveling and sealing layers,suitable for both new constructions and repairs of existing roads.The insights gained from this review not only clarify the distinctions between various structural layers but also provide practical guidelines for enhancing the design and implementation of PCP.This work contributes to advancing sustainable and resilient road construction practices,making it a significant reference for researchers and practitioners in the field.
基金financially supported by the National Natural Science Foundation of China(Nos.21574076,U1510121,21501113,61504076 and 21407100)the Science Foundation of Shanxi province(Nos.2014011016-1 and 2015021129)the Program for the Top Young and Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.020352901014)
文摘Flexible electrochemical capacitors（ECs） are vitally important as the emerging flexible electronics.We have prepared polypyrrole doped with counter ion of Cl-on carbon fibers（PPy-Cl/CFs） via the simple electrochemical deposition method.The flexible ECs based on PPy-Cl/CFs electrodes have been assembled by using H_3PO_4/poly（vinyl alcohol）（PVA）,H_2SO_4/PVA,LiClO_4/PVA,KCl/PVA and Li Cl/PVA as gel electrolytes.The capacitive properties of ECs have been systematically evaluated with electrochemical methods.The results show that the cells with H_3PO_4/PVA electrolyte exhibit good cyclic stability（91.5% retention after 15000 cycles） although PPy-Cl/CFs has moderate specific capacitance in H_3PO_4/PVA（41.6 m F·cm^-1 or 52.0 F·cm^-3）.However,the ECs in other electrolytes have poor cyclic stability.Further electrochemical analysis reveals that the doping/dedoping processes of PPy-Cl/CFs are different in the five electrolytes,and X-ray photoelectron spectra demonstrate that the ratios of counter anions in PPy＇s oxidized states to those in reduced states are obviously different when PPy-Cl/CFs are kept in reduced or oxidized states in the five electrolytes.The results also illustrate why the capacitors using H_3PO_4/PVA as electrolyte exhibit good cyclic stability.Furthermore,a light emitting diode（LED） with a threshold voltage of 2.5 V can be lighted by three ECs connected in series.
基金Sponsored by the Natural Science Foundation of Shandong Province of China (Grant No. ZR2019MEE047)the National Key Research and Development Project of China (Grant No. 2020YFB1901403)CSCEC Technical and Development Plan (Grant No. CSCEC-2020-Z-35)。
文摘Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This paper presents a new type of assembled connection joint for the high-rise modularized construction. Cyclic shear tests of full-scale joints were carried out, and the key indexes of their seismic performances including the hysteretic performance, ductility, and energy dissipation capacity were analyzed and obtained. The results show that the hysteresis loops of longitudinal and lateral cyclic shear tests were both plump in shapes. The ductility coefficients were 4.54 and 4.98, and the energy dissipation coefficients were 1.83 and 1.43, respectively. The test joint had good ductility and energy dissipation capacity. The positions of yield failure of specimens were mainly concentrated in the connection areas between the column and short beam or end-plate. The research can provide the technical reference for the seismic design and engineering application of related modularized constructions.
基金financially and jointly supported by the R&D Program of Department of Housing and Urban-Rural Development of Hubei Province(Grant No.202023)Wuhan Municipal Engineering Group(Grant No.202105)。
文摘Prefabricated pavement is increasingly applied worldwide due to the rapid construction on-site.This paper presents a state-of-the-art review of the precast systems and assembly connection of concrete slabs,as well as the precast pavement features.The previous research indicates that:(1)both super-slab and Michigan systems are recommended with the satisfied road performance close to the cast-in-place;(2)flexible base material is suggested for the fabricated pavement for the satisfied leveling and stress distribution;(3)to prevent the voiding phenomenon of the fabricated pavement,the sand cushion course,dry mixed mortar or self-leveling mortar,and other flowable materials could be used for the secondary leveling of the base after the pavement splicing;(4)two-direction dowel bars are recommended for slab connections of the fabricated pavement,which helps to improve the load transfer capacity of the joints and enhance the durability of the fabricated pavement structure;(5)the sealing treatment of precast slab joints needs strengthening to reduce the impact of surface runoff on the base course;(6)the further research focuses are designing with functional,composite,mechanized,intelligent,lightweight,and flexible pavement slabs.Besides,pavement mechanical properties induced by temperature overlapping traffic loads need to be revealed.
