The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride so...The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.展开更多
In the corrosive environment of carbonaceous mudstone,the mechanical properties of grouting materials in the anchorage section of anchor bolts continue to deteriorate.In response,a cement-based modified anchoring grou...In the corrosive environment of carbonaceous mudstone,the mechanical properties of grouting materials in the anchorage section of anchor bolts continue to deteriorate.In response,a cement-based modified anchoring grouting material(MAGM)with high corrosion resistance was developed.The results reveal that compared with those of ordinary Portland cement(OPC)grouting material,the compressive strength,tensile strength,and shear stress peak of the MAGM increased by 85.9%,44.4%and 45.4%,respectively,after 28 d of corrosion in a carbonaceous mudstone solution.Waterborne epoxy resin and curing agent create a network membrane structure under the action of nano-Al_(2)O_(3)to protect the cement hydration products.In the corrosive environment of carbonaceous mudstone,corrosion products formed on the surface of the stone body have adsorbed onto the reticular membrane structure,filling the pores of the stone body and slowing the erosion rate of ions.After 365 d of application of MAGM and OPC in the corrosive environment of a carbonaceous mudstone slope,the peak shear stress of MAGM is,on average,55.3%greater than that of OPC.展开更多
The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,h...The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.展开更多
The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely ...The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely applied to address issues such as seepage,leakage,and alignment correction in shield tunnels.This study investigates the additional stress induced by grouting in silty soil layers,using cement-based grouts with different water-to-cement ratios and polyurethane-modified cement-based materials.Results show that additional stress decreases with depth and is more influenced by horizontal distance from the grouting point.In staged grouting,the first injection phase contributes about 50%of the peak additional stress.A lower water-to-cement ratio(e.g.,0.6)increases additional stress but reduces grout flowability,while a higher ratio improves diffusion but increases the risk of grout loss.(≥1.0)The polyurethane-modified cement-based material enhances stress transfer performance,increasing peak additional stress by approximately 10%.These findings provide theoretical guidance for optimizing material selection and grouting design in metro tunnel repair within silty soil layers.展开更多
Cement-based composite grouting materials were used to construct grouting cutoff wall for heavy metal contaminated soil in non-ferrous metal mining areas. Cement, fly ash, and slag as principal ingredients were mixed ...Cement-based composite grouting materials were used to construct grouting cutoff wall for heavy metal contaminated soil in non-ferrous metal mining areas. Cement, fly ash, and slag as principal ingredients were mixed with water glass in different ways to produce three composite grouting materials. In order to investigate the effect of water glass mixing ratio, Baume degree, fly ash and slag contents on the mechanical properties of the composite grouting materials, particularly their gel time and compressive strength, the beaker-to-beaker method of gel time test and unconfined compressive strength test were conducted. In addition, the phase composition and microstructure of the composite grouting materials were analyzed by the X-ray diffraction（XRD） and scanning electron microscope（SEM） techniques. The test results show that their gel time increases when water glass mixing ratio and Baume degree increase. The gel time increases dramatically when fly ash is added, but decreases slightly if fly ash is partly replaced by slag. When the mixing ratio of water glass is below 20%, their compressive strength increases with the increases of the ratio; when the ratio is above 20%, it significantly decreases. The compressive strength also tends to increase as Baume degree increases, and improves if fly ash and slag are added.展开更多
In order to study the influence of temperature on compressive strength of polymer grouting material,the compression specimen injection mold is self-made,and the uniaxial compressive test was carried out in the tempera...In order to study the influence of temperature on compressive strength of polymer grouting material,the compression specimen injection mold is self-made,and the uniaxial compressive test was carried out in the temperature control box under different temperatures.The change regularity of compressive strength of polymer grouting material under different temperatures and the law of volume changes of polymer samples were obtained.The experimental results show that：the compressive strength of polymer material increases with the increase of density;the temperature change has a certain influence on the compressive strength of polymer grouting material;the compressive strength decreases with temperature increases under the same density,but the compressive strength is not significantly affected by temperature when the density is less than 0.4 g/cm3;the volume change of the samples accords with the law of thermal expansion and contraction when temperature changes,and the increase of the volume is obvious when it is under high temperature.The achievements will provide an important basis to the application of the polymer grouting material.展开更多
A new clay-cement composite grouting material (CCGM) for tunnelling in underwater karst area was developed through the excellent synergistic interactions among cement, clay, meta-aluminate and lignin. The probable for...A new clay-cement composite grouting material (CCGM) for tunnelling in underwater karst area was developed through the excellent synergistic interactions among cement, clay, meta-aluminate and lignin. The probable formation mechanism of the material was proposed based on a series of experimental tests. The results show that with an optimal mass ratio (2:1:1:0.024) for water, cement, clay and additives, the obtained CCGM displayed an excellent grouting performance for karst in an underwater condition. Compared with neat cement grouts and clay-cement grouts, CCGM has faster gel time, lower bleeding rate and bulk shrinkage rate, greater initial viscosity, and a strong resistance to water dispersion. A successful engineering application indicates that CCGM not only fulfils a better grouting performance for karst in underwater conditions but also reduces the engineering cost and environmental pollution.展开更多
Grouting is the most commonly used method to control water inrush in underground engineering.Traditional cement-based materials are easy to dilute and hard to coagulate under the influence of large flow and high-veloc...Grouting is the most commonly used method to control water inrush in underground engineering.Traditional cement-based materials are easy to dilute and hard to coagulate under the influence of large flow and high-velocity water inrush.To address these deficiencies,a new type of polymer grouting material with an excellent expansion ratio was synthesised.The material quickly absorbs water and has an expansion ratio of 1:300.The material is composed of a superabsorbent polymer(SAP),glycerol,and ethanol.The effects of water quality on the expansion ratio and expansion rate of the material were examined,and the best solid–liquid ratio for the slurry was determined by fluidity measurements.A karst specially designed pipeline water inrush test device showed that 800 g of SAP can achieve 0.6 m/s water flow blockage in the smooth pipeline,demonstrating that the ability of the SAP slurry to block water inrush is superior to those of other materials.This study provides a reference for water inrush plugging,and has important implications for the reduction and control of karst pipeline-type water inrush disasters,ensuring the safety of construction sites and preventing loss of life and damage to property.展开更多
The rheological and mechanical properties of high-strength anchorage grouting materials for highway slope were investigated to optimize the mix proportion. The experimental results showed that the optimized mix propor...The rheological and mechanical properties of high-strength anchorage grouting materials for highway slope were investigated to optimize the mix proportion. The experimental results showed that the optimized mix proportion of high-strength anchorage grouting material （HAGM） was C3 （FA：SP-SF= 1：2：2; AGI：AG2=3：7 and 0.03% FC）, which is agreement with the limitation of JCT 986-2005. Moreover, the XRD and FTIR results showed the addition of expansive components was in favor of the formation of ettringite. The intensity of AFt oeak of the samnles increased with the increasing of hydration time.展开更多
Main performance of the cement grouting materials made up by Portland cement（PC） and sulphoaluminate cement（SAC） was investigated in this program, a kind of expanding agent（EA） which was mainly constituted by me...Main performance of the cement grouting materials made up by Portland cement（PC） and sulphoaluminate cement（SAC） was investigated in this program, a kind of expanding agent（EA） which was mainly constituted by metakaolin and alunite was utilized for the compensation of the shrinkage, the hydration products and micro structure of the grouting materials were researched by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results showed that a high expansion rate of the grouting materials could be reached as the expanding agent mixed in 6% of PC mass; the addition of SAC in the S2（PC：SAC：EA=34：6：2.25） brought a further improvement of the expansion rate of the grouting materials, the analysis of XRD and SEM showed that due to the reaction of expanding agent and SAC in the grouting materials, more ettringite crystal was generated, which resulted in a higher early strength, the addition of SAC played an expansion and strength reinforcement role in the grouting materials.展开更多
The pore structure and porosity of three kinds of mine grouting materials were characterized based on a thin-section analysis and low-field nuclear magnetic resonance (NMR) technique. The macroscopic pore interconnect...The pore structure and porosity of three kinds of mine grouting materials were characterized based on a thin-section analysis and low-field nuclear magnetic resonance (NMR) technique. The macroscopic pore interconnectivity was investigated using binary images captured from thin sections and a random walk pore spectral dimension (RWPSD) algorithm. The experimental results show that the microstructure of the grouting materials used consisted of interlayer pores, gel pores, capillary pores, circular air holes, and small fractures, and tailings can fill some gaps in the hydration product structure and dense hydration products. There is a positive correlation between pore interconnectivity and curing time. In addition, there is a relationship between pore interconnectivity and porosity. With increasing porosity and pore interconnectivity, a non-uniform pore structure occurs in mine grouting materials with an accelerator and results in reduced setting time and later strength.展开更多
Mine grouting reinforcement and water plugging projects often require large amounts of grouting materials.To reduce the carbon emission of grouting material production,improve the utilization of solid waste from minin...Mine grouting reinforcement and water plugging projects often require large amounts of grouting materials.To reduce the carbon emission of grouting material production,improve the utilization of solid waste from mining enterprises,and meet the needs of mine reinforcement and seepage control,a double-liquid grouting material containing a high admixture of coal gangue powder/bottom ash geopolymer was studied.The setting time,fluidity,bleeding rate,and mechanical properties of grouting materials were studied through laboratory tests,and SEM analyzed the microstructure of the materials.The results show that the total mixture of calcined gangue does not exceed 60%.And the proportion of bottom ash replacing cement should be within 30%.At the same time,the volume mixture of sodium silicate is 20%.And the water-solid ratio does not exceed 0.6.The stability of the slurry prepared under this ratio is good.The microstructure of the stone body is dense,and its strength can meet the requirements of rock reinforcement and seepage control.Its economic and environmental benefits are more significant than the traditional cement-silicate double-liquid grouting material.展开更多
Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates ...Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates and grouting materials were designed according to connection configurations with different bolt diameters and end distance of bolt holes,and their bearing capacities and failure modes were analyzed by static tension tests.According to the test results of all connectors,the failure modes of the specimens are divided into four categories,and the effects of bolt diameter and bolt hole end distance on the connection bearing capacity and failure mode are analyzed.The test results show that the deformation and failure process can be divided into four stages.The main influence factor of connector bearing capacity is bolt diameter.Connectors can be divided into four failure modes,and brittle failure can be avoided by adopting certain structural measures.Filling with grouting material can improve the bearing capacity of joints.Due to the large variability of bamboo,further experiments are needed.展开更多
This study is aimed at the thermal analysis of sealant mortar （usually a mixtures of bentonite and cemem with addition of sand） used in geothermal cooling and heating. In particular, thermal conductivity and diffusi...This study is aimed at the thermal analysis of sealant mortar （usually a mixtures of bentonite and cemem with addition of sand） used in geothermal cooling and heating. In particular, thermal conductivity and diffusivity measurements were performed on differem sealant mixtures by using Hot Disk thermal constants analyzer in order to identify the interesting thermal properties of grouting materials. The grouting materials that we considered are of porous nature and, if used in the presence of groundwater, have different levels of imbibitions. It is important to know the thermal behavior of these materials at different water content. A first set of measurements was performed on a not-tinted material at room temperature; then the samples were led to saturation conditions by contact capillary imbibitions with a cotton wool layer moistened in water. The determination of thermal conductivity in these test conditions appears to be critical compared to the measuremems on non-timed sample. The thermal conductivity tests have revealed how the thermal behavior of the samples analyzed is essentially determined by the density and water content of the material： in fact, the thermal conductivity increases of two to three times the value of the not-tinted material.展开更多
A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidificatio...A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidification, carbonization and activation. Nitrogen adsorption and mercury porosimetry show that mixed nanopores and micropores coexist in MNC with a high specific surface area of 1978 m2·g-1 and a total pore volume of 0.99 cm3·g-1. In addition, the MNC is found to consist of EG and activated carbon with the latter deposited on the interior and the exterior surfaces of the EG pores. The thickness of the activated carbon layer is calculated to be about one hundred nanometers and is further confirmed by scanning electron microscope (SEM) and transmission election microscope (TEM). A maximum static phenol adsorption of 241.2 mg·g-1 was obtained by using MNC, slightly higher than that of 220.4 mg·g-1 by using commercial activated carbon (CAC). The phenol adsorption kinetics were investigated and the data fitted well to a pseudo-second-order model. Also, an intra-particle diffusion mechanism was proposed. Furthermore, it is found that the dynamic adsorption capacity of MNC is nearly three times that of CAC. The results suggest that the MNC is a more efficient adsorbent than CAC for the removal of phenol from aqueous solution.展开更多
Research efforts on electromagnetic interference(EMI)shielding materials have begun to converge on green and sustainable biomass materials.These materials offer numerous advantages such as being lightweight,porous,and...Research efforts on electromagnetic interference(EMI)shielding materials have begun to converge on green and sustainable biomass materials.These materials offer numerous advantages such as being lightweight,porous,and hierarchical.Due to their porous nature,interfacial compatibility,and electrical conductivity,biomass materials hold significant potential as EMI shielding materials.Despite concerted efforts on the EMI shielding of biomass materials have been reported,this research area is still relatively new compared to traditional EMI shielding materials.In particular,a more comprehensive study and summary of the factors influencing biomass EMI shielding materials including the pore structure adjustment,preparation process,and micro-control would be valuable.The preparation methods and characteristics of wood,bamboo,cellulose and lignin in EMI shielding field are critically discussed in this paper,and similar biomass EMI materials are summarized and analyzed.The composite methods and fillers of various biomass materials were reviewed.this paper also highlights the mechanism of EMI shielding as well as existing prospects and challenges for development trends in this field.展开更多
Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the sur...Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the surrounding rock.The performance of grouting is primarily governed by the flow behavior and diffusion extent of the slurry.This review considers recent advances in the theory and methodology of slurry flow and diffusion in fractured rock.It examines commonly used grout materials,including cement-based,chemical,and composite formulations,each offering distinct advantages for specific geological conditions.Themechanisms of reinforcement vary significantly across materials,requiring tailored application strategies.The rheological properties of grouting slurries,particularly cement-based types,have been widely modeled using classical constitutive approaches.However,the influence of time-and space-dependent viscosity evolution on slurry behavior remains underexplored.Experimental studies have provided valuable insights into slurry diffusion,yet further research is needed to capture real-time behavior under multi-scale and multi-physics coupling conditions.Similarly,current numerical simulations are largely limited to twoand three-dimensional models of single-fracture flow.These models often neglect the complexity of fracture networks and geological heterogeneity,highlighting a need for more realistic and integrated simulation frameworks.Future research should focus on:(1)fine-scale modeling of slurry hydration and mechanical reinforcement processes;(2)cross-scale analysis of slurry flow under coupled thermal,hydraulic,andmechanical fields;and(3)development of realtime,three-dimensional dynamic simulation tools to capture the full grouting process.These efforts will strengthen the theoretical foundation and practical effectiveness of grouting in complex underground environments.展开更多
Radiative cooling is a passive thermal management strategy that leverages the natural ability of materials to dissipate heat through infrared radiation.It has significant implications for energy efficiency,climate ada...Radiative cooling is a passive thermal management strategy that leverages the natural ability of materials to dissipate heat through infrared radiation.It has significant implications for energy efficiency,climate adaptation,and sustainable technology development,with applications in personal thermal management,building temperature regulation,and aerospace engineering.However,radiative cooling performance is susceptible to environmental aging and special environmental conditions,limiting its applicability in extreme environments.Herein,a critical review of extreme environmental radiative cooling is presented,focusing on enhancing environmental durability and cooling efficiency.This review first introduces the design principles of heat exchange channels,which are tailored based on the thermal flow equilibrium to optimize radiative cooling capacity in various extreme environments.Subsequently,recent advancements in radiative cooling materials and micronano structures that align with these principles are systematically discussed,with a focus on their implementation in terrestrial dwelling environments,terrestrial extreme environments,aeronautical environments,and space environments.Moreover,this review evaluates the cooling effects and anti-environmental abilities of extreme radiative cooling devices.Lastly,key challenges hindering the development of radiative cooling devices for extreme environmental applications are outlined,and potential strategies to overcome these limitations are proposed,aiming to prompt their future commercialization.展开更多
Spiking neural network(SNN),widely known as the third-generation neural network,has been frequently investigated due to its excellent spatiotemporal information processing capability,high biological plausibility,and l...Spiking neural network(SNN),widely known as the third-generation neural network,has been frequently investigated due to its excellent spatiotemporal information processing capability,high biological plausibility,and low energy consumption characteristics.Analogous to the working mechanism of human brain,the SNN system transmits information through the spiking action of neurons.Therefore,artificial neurons are critical building blocks for constructing SNN in hardware.Memristors are drawing growing attention due to low consumption,high speed,and nonlinearity characteristics,which are recently introduced to mimic the functions of biological neurons.Researchers have proposed multifarious memristive materials including organic materials,inorganic materials,or even two-dimensional materials.Taking advantage of the unique electrical behavior of these materials,several neuron models are successfully implemented,such as Hodgkin–Huxley model,leaky integrate-and-fire model and integrate-and-fire model.In this review,the recent reports of artificial neurons based on memristive devices are discussed.In addition,we highlight the models and applications through combining artificial neuronal devices with sensors or other electronic devices.Finally,the future challenges and outlooks of memristor-based artificial neurons are discussed,and the development of hardware implementation of brain-like intelligence system based on SNN is also prospected.展开更多
This article studies the influence of the fineness of cement, fly ash(FA), its composite admixture and the amount and way mixed with superplasticizer on the rheological properties of micro fine cement(MC). By means of...This article studies the influence of the fineness of cement, fly ash(FA), its composite admixture and the amount and way mixed with superplasticizer on the rheological properties of micro fine cement(MC). By means of modern instruments and technologies (such as XRD, SEM, laser granulometer and superficial potential apparatus etc.), the article studies the mineral compositions, the appearance character of grains, particle size distribution and superficial potential of FA and its composite materials. And through that, the reducing mechanism of FA is thoroughly analyzed. The study shows that FA and its composite admixture are excellent components which can effectively improve the rheological properties of micro fine cement, and that the superplasticizer has a saturation point and the mixing way of it has a great influence on the rheological properties.展开更多
基金Funded by a Science and Technology Project from the Ministry of Housing and Urban-Rural Development of the People’s Republic of China(No.2019-K-047)Yangzhou Government-Yangzhou University Cooperative Platform Project for Science and Technology Innovation(No.YZ2020262)。
文摘The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.
基金Projects(52278439,51838001)supported by the National Natural Science Foundation of ChinaProject(2023RC3138)supported by the Science and Technology Innovation Plan Project of Hunan Province,China+2 种基金Project(21B0317)supported by the Natural Science Youth Project of Education Department of Hunan Province,ChinaProject(2022JJ40500)supported by the Natural Science Foundation of Hunan Province,ChinaProject(21KB13)supported by the Open Fund of Key Laboratory of Safety Control of Bridge Engineering,Ministry of Education(Changsha University of Science&Technology),China。
文摘In the corrosive environment of carbonaceous mudstone,the mechanical properties of grouting materials in the anchorage section of anchor bolts continue to deteriorate.In response,a cement-based modified anchoring grouting material(MAGM)with high corrosion resistance was developed.The results reveal that compared with those of ordinary Portland cement(OPC)grouting material,the compressive strength,tensile strength,and shear stress peak of the MAGM increased by 85.9%,44.4%and 45.4%,respectively,after 28 d of corrosion in a carbonaceous mudstone solution.Waterborne epoxy resin and curing agent create a network membrane structure under the action of nano-Al_(2)O_(3)to protect the cement hydration products.In the corrosive environment of carbonaceous mudstone,corrosion products formed on the surface of the stone body have adsorbed onto the reticular membrane structure,filling the pores of the stone body and slowing the erosion rate of ions.After 365 d of application of MAGM and OPC in the corrosive environment of a carbonaceous mudstone slope,the peak shear stress of MAGM is,on average,55.3%greater than that of OPC.
基金supported by the National Natural Science Foundation of China,Grant Nos.42477185,41602308the Zhejiang Provincial Natural Science Foundation of China,Grant No.LY20E080005+2 种基金the Zhejiang Province University Students Science and Technology Innovation Program,Grant No.0201310P28the PostGraduate Course Construction Project of Zhejiang University of Science and Technology,Grant No.2021yjskj05the Zhejiang University of Science and Technology Graduate Research and Innovation Fund,Grant No.2023yjskc10.
文摘The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.
基金supported by the National Natural Science Foundation of China(No.42477185)Natural Science Foundation of Zhejiang Province(LQ24A020015)+1 种基金Research Achievement Award Cultivation Project of Zhejiang University of Science and Technology(2023JLYB001)the Postgraduate Course Construction Project of Zhejiang University of Science and Technology(2024yjskj05).
文摘The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely applied to address issues such as seepage,leakage,and alignment correction in shield tunnels.This study investigates the additional stress induced by grouting in silty soil layers,using cement-based grouts with different water-to-cement ratios and polyurethane-modified cement-based materials.Results show that additional stress decreases with depth and is more influenced by horizontal distance from the grouting point.In staged grouting,the first injection phase contributes about 50%of the peak additional stress.A lower water-to-cement ratio(e.g.,0.6)increases additional stress but reduces grout flowability,while a higher ratio improves diffusion but increases the risk of grout loss.(≥1.0)The polyurethane-modified cement-based material enhances stress transfer performance,increasing peak additional stress by approximately 10%.These findings provide theoretical guidance for optimizing material selection and grouting design in metro tunnel repair within silty soil layers.
基金Projects(41472278,41202220)supported by the National Natural Science Foundation of ChinaProject(20120022120003)supported by the Research Fund for the Doctoral Program of Higher Education,China+1 种基金Project(51900265647)supported by the Beijing Higher Education Young Elite Teacher Project,ChinaProject(2652012065)supported by the Fundamental Research Funds for the Central Universities,China
文摘Cement-based composite grouting materials were used to construct grouting cutoff wall for heavy metal contaminated soil in non-ferrous metal mining areas. Cement, fly ash, and slag as principal ingredients were mixed with water glass in different ways to produce three composite grouting materials. In order to investigate the effect of water glass mixing ratio, Baume degree, fly ash and slag contents on the mechanical properties of the composite grouting materials, particularly their gel time and compressive strength, the beaker-to-beaker method of gel time test and unconfined compressive strength test were conducted. In addition, the phase composition and microstructure of the composite grouting materials were analyzed by the X-ray diffraction（XRD） and scanning electron microscope（SEM） techniques. The test results show that their gel time increases when water glass mixing ratio and Baume degree increase. The gel time increases dramatically when fly ash is added, but decreases slightly if fly ash is partly replaced by slag. When the mixing ratio of water glass is below 20%, their compressive strength increases with the increases of the ratio; when the ratio is above 20%, it significantly decreases. The compressive strength also tends to increase as Baume degree increases, and improves if fly ash and slag are added.
文摘In order to study the influence of temperature on compressive strength of polymer grouting material,the compression specimen injection mold is self-made,and the uniaxial compressive test was carried out in the temperature control box under different temperatures.The change regularity of compressive strength of polymer grouting material under different temperatures and the law of volume changes of polymer samples were obtained.The experimental results show that：the compressive strength of polymer material increases with the increase of density;the temperature change has a certain influence on the compressive strength of polymer grouting material;the compressive strength decreases with temperature increases under the same density,but the compressive strength is not significantly affected by temperature when the density is less than 0.4 g/cm3;the volume change of the samples accords with the law of thermal expansion and contraction when temperature changes,and the increase of the volume is obvious when it is under high temperature.The achievements will provide an important basis to the application of the polymer grouting material.
基金Project(51608539)supported by the National Natural Science Foundation of ChinaProjects(2016M592451,2017T100610)supported by the China Postdoctoral Science Foundation
文摘A new clay-cement composite grouting material (CCGM) for tunnelling in underwater karst area was developed through the excellent synergistic interactions among cement, clay, meta-aluminate and lignin. The probable formation mechanism of the material was proposed based on a series of experimental tests. The results show that with an optimal mass ratio (2:1:1:0.024) for water, cement, clay and additives, the obtained CCGM displayed an excellent grouting performance for karst in an underwater condition. Compared with neat cement grouts and clay-cement grouts, CCGM has faster gel time, lower bleeding rate and bulk shrinkage rate, greater initial viscosity, and a strong resistance to water dispersion. A successful engineering application indicates that CCGM not only fulfils a better grouting performance for karst in underwater conditions but also reduces the engineering cost and environmental pollution.
基金the financial supports from National Key Research and Development Project(No.2019YFC1805402)National Natural Science Foundation of China(Nos.U1906229 and U1706223)Project supported by the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.52021005)。
文摘Grouting is the most commonly used method to control water inrush in underground engineering.Traditional cement-based materials are easy to dilute and hard to coagulate under the influence of large flow and high-velocity water inrush.To address these deficiencies,a new type of polymer grouting material with an excellent expansion ratio was synthesised.The material quickly absorbs water and has an expansion ratio of 1:300.The material is composed of a superabsorbent polymer(SAP),glycerol,and ethanol.The effects of water quality on the expansion ratio and expansion rate of the material were examined,and the best solid–liquid ratio for the slurry was determined by fluidity measurements.A karst specially designed pipeline water inrush test device showed that 800 g of SAP can achieve 0.6 m/s water flow blockage in the smooth pipeline,demonstrating that the ability of the SAP slurry to block water inrush is superior to those of other materials.This study provides a reference for water inrush plugging,and has important implications for the reduction and control of karst pipeline-type water inrush disasters,ensuring the safety of construction sites and preventing loss of life and damage to property.
基金Funded by the National Natural Science Foundation of China(No.41202226)the Program for Department of Communications of Yunnan Province(No.2009(A)1-09)
文摘The rheological and mechanical properties of high-strength anchorage grouting materials for highway slope were investigated to optimize the mix proportion. The experimental results showed that the optimized mix proportion of high-strength anchorage grouting material （HAGM） was C3 （FA：SP-SF= 1：2：2; AGI：AG2=3：7 and 0.03% FC）, which is agreement with the limitation of JCT 986-2005. Moreover, the XRD and FTIR results showed the addition of expansive components was in favor of the formation of ettringite. The intensity of AFt oeak of the samnles increased with the increasing of hydration time.
基金Funded by the National Key Technology R&D Program in the12th Five Year Plan of China(No.2011BAE14B06)the National High Technology ResearchDevelopment Program of China(No.2015AA034701)
文摘Main performance of the cement grouting materials made up by Portland cement（PC） and sulphoaluminate cement（SAC） was investigated in this program, a kind of expanding agent（EA） which was mainly constituted by metakaolin and alunite was utilized for the compensation of the shrinkage, the hydration products and micro structure of the grouting materials were researched by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The results showed that a high expansion rate of the grouting materials could be reached as the expanding agent mixed in 6% of PC mass; the addition of SAC in the S2（PC：SAC：EA=34：6：2.25） brought a further improvement of the expansion rate of the grouting materials, the analysis of XRD and SEM showed that due to the reaction of expanding agent and SAC in the grouting materials, more ettringite crystal was generated, which resulted in a higher early strength, the addition of SAC played an expansion and strength reinforcement role in the grouting materials.
基金Project(41672298) supported by the National Natural Science Foundation of ChinaProject(2017YFC0602901) supported by the National Key Research and Development Program of China
文摘The pore structure and porosity of three kinds of mine grouting materials were characterized based on a thin-section analysis and low-field nuclear magnetic resonance (NMR) technique. The macroscopic pore interconnectivity was investigated using binary images captured from thin sections and a random walk pore spectral dimension (RWPSD) algorithm. The experimental results show that the microstructure of the grouting materials used consisted of interlayer pores, gel pores, capillary pores, circular air holes, and small fractures, and tailings can fill some gaps in the hydration product structure and dense hydration products. There is a positive correlation between pore interconnectivity and curing time. In addition, there is a relationship between pore interconnectivity and porosity. With increasing porosity and pore interconnectivity, a non-uniform pore structure occurs in mine grouting materials with an accelerator and results in reduced setting time and later strength.
基金Funding Statement:The research described in this paper was financially supported by the National Natural Science Foundation of China(No.51974172)Innovation and Technology Program of Universities in Shandong Province,China(No.2020KJH001)+1 种基金National Natural Science Foundation of China(No.52274131)State Key Laboratory of Coal Mining and Clean Utilization(No.2021-CMCU-KF017).
文摘Mine grouting reinforcement and water plugging projects often require large amounts of grouting materials.To reduce the carbon emission of grouting material production,improve the utilization of solid waste from mining enterprises,and meet the needs of mine reinforcement and seepage control,a double-liquid grouting material containing a high admixture of coal gangue powder/bottom ash geopolymer was studied.The setting time,fluidity,bleeding rate,and mechanical properties of grouting materials were studied through laboratory tests,and SEM analyzed the microstructure of the materials.The results show that the total mixture of calcined gangue does not exceed 60%.And the proportion of bottom ash replacing cement should be within 30%.At the same time,the volume mixture of sodium silicate is 20%.And the water-solid ratio does not exceed 0.6.The stability of the slurry prepared under this ratio is good.The microstructure of the stone body is dense,and its strength can meet the requirements of rock reinforcement and seepage control.Its economic and environmental benefits are more significant than the traditional cement-silicate double-liquid grouting material.
基金support from 111 Project(Grant No.B18062)the Graduate Research and Innovation Foundation of Chongqing in China(Grant No.CYS20026)the National Key Research and Development Program of China(Grant No.2017YFC0703504).
文摘Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates and grouting materials were designed according to connection configurations with different bolt diameters and end distance of bolt holes,and their bearing capacities and failure modes were analyzed by static tension tests.According to the test results of all connectors,the failure modes of the specimens are divided into four categories,and the effects of bolt diameter and bolt hole end distance on the connection bearing capacity and failure mode are analyzed.The test results show that the deformation and failure process can be divided into four stages.The main influence factor of connector bearing capacity is bolt diameter.Connectors can be divided into four failure modes,and brittle failure can be avoided by adopting certain structural measures.Filling with grouting material can improve the bearing capacity of joints.Due to the large variability of bamboo,further experiments are needed.
文摘This study is aimed at the thermal analysis of sealant mortar （usually a mixtures of bentonite and cemem with addition of sand） used in geothermal cooling and heating. In particular, thermal conductivity and diffusivity measurements were performed on differem sealant mixtures by using Hot Disk thermal constants analyzer in order to identify the interesting thermal properties of grouting materials. The grouting materials that we considered are of porous nature and, if used in the presence of groundwater, have different levels of imbibitions. It is important to know the thermal behavior of these materials at different water content. A first set of measurements was performed on a not-tinted material at room temperature; then the samples were led to saturation conditions by contact capillary imbibitions with a cotton wool layer moistened in water. The determination of thermal conductivity in these test conditions appears to be critical compared to the measuremems on non-timed sample. The thermal conductivity tests have revealed how the thermal behavior of the samples analyzed is essentially determined by the density and water content of the material： in fact, the thermal conductivity increases of two to three times the value of the not-tinted material.
基金financially supported by the Fundamental Research Funds for the National Natural Science Foundation of China(Nos.21071107,21277094,and21103119)Production and Research Collaborative Innovation Project of Jiangsu Province(No.BY2012123)+9 种基金Natural Science Foundation of Jiangsu Province(No.BK2012167)Scienceand Technology Pillar Program(Industry)of Jiangsu Province(No.BE2012101)Collegiate Natural Science Fund of Jiangsu Province(Nos.12KJA430005,09KJB30003,and11KJB430012)Key Laboratory for Environment Functional Materials of Suzhou(No.SZS201008)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),Applied Basic Research Project of Suzhou(No.SYG201242)Industrial Surport Project of Suzhou(No.SG201138)Jiangsu Key Laboratory of Material Tribology(No.Kjsmcx2011001)Jiangsu Key Laboratory for Photon Manufacturing(No.GZ201111)Jiangsu Provincial Key Laboratory for Interventional Medical Devices(No.Jr1210)Creative Project of Postgraduate of Jiangsu Province(No.CXZZ11_0954)
文摘A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidification, carbonization and activation. Nitrogen adsorption and mercury porosimetry show that mixed nanopores and micropores coexist in MNC with a high specific surface area of 1978 m2·g-1 and a total pore volume of 0.99 cm3·g-1. In addition, the MNC is found to consist of EG and activated carbon with the latter deposited on the interior and the exterior surfaces of the EG pores. The thickness of the activated carbon layer is calculated to be about one hundred nanometers and is further confirmed by scanning electron microscope (SEM) and transmission election microscope (TEM). A maximum static phenol adsorption of 241.2 mg·g-1 was obtained by using MNC, slightly higher than that of 220.4 mg·g-1 by using commercial activated carbon (CAC). The phenol adsorption kinetics were investigated and the data fitted well to a pseudo-second-order model. Also, an intra-particle diffusion mechanism was proposed. Furthermore, it is found that the dynamic adsorption capacity of MNC is nearly three times that of CAC. The results suggest that the MNC is a more efficient adsorbent than CAC for the removal of phenol from aqueous solution.
基金National Natural Science Foundation of China(32201491)Young Elite Scientists Sponsorship Program by CAST(2023QNRC001)The authors extend their appreciation to the Deanship of Scientific Research at Northern Border University,Arar,KSA for funding this research work through the project number“NBU-FPEJ-2024-1101-02”.
文摘Research efforts on electromagnetic interference(EMI)shielding materials have begun to converge on green and sustainable biomass materials.These materials offer numerous advantages such as being lightweight,porous,and hierarchical.Due to their porous nature,interfacial compatibility,and electrical conductivity,biomass materials hold significant potential as EMI shielding materials.Despite concerted efforts on the EMI shielding of biomass materials have been reported,this research area is still relatively new compared to traditional EMI shielding materials.In particular,a more comprehensive study and summary of the factors influencing biomass EMI shielding materials including the pore structure adjustment,preparation process,and micro-control would be valuable.The preparation methods and characteristics of wood,bamboo,cellulose and lignin in EMI shielding field are critically discussed in this paper,and similar biomass EMI materials are summarized and analyzed.The composite methods and fillers of various biomass materials were reviewed.this paper also highlights the mechanism of EMI shielding as well as existing prospects and challenges for development trends in this field.
基金funded by the National Natural Science Foundation of China[U22A20234]Hubei Province key research and development project[2023BCB121]Wuhan innovation supporting projects[2023020201010079].
文摘Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the surrounding rock.The performance of grouting is primarily governed by the flow behavior and diffusion extent of the slurry.This review considers recent advances in the theory and methodology of slurry flow and diffusion in fractured rock.It examines commonly used grout materials,including cement-based,chemical,and composite formulations,each offering distinct advantages for specific geological conditions.Themechanisms of reinforcement vary significantly across materials,requiring tailored application strategies.The rheological properties of grouting slurries,particularly cement-based types,have been widely modeled using classical constitutive approaches.However,the influence of time-and space-dependent viscosity evolution on slurry behavior remains underexplored.Experimental studies have provided valuable insights into slurry diffusion,yet further research is needed to capture real-time behavior under multi-scale and multi-physics coupling conditions.Similarly,current numerical simulations are largely limited to twoand three-dimensional models of single-fracture flow.These models often neglect the complexity of fracture networks and geological heterogeneity,highlighting a need for more realistic and integrated simulation frameworks.Future research should focus on:(1)fine-scale modeling of slurry hydration and mechanical reinforcement processes;(2)cross-scale analysis of slurry flow under coupled thermal,hydraulic,andmechanical fields;and(3)development of realtime,three-dimensional dynamic simulation tools to capture the full grouting process.These efforts will strengthen the theoretical foundation and practical effectiveness of grouting in complex underground environments.
基金supported by the National Natural Science Foundation of China(52172120)Shanghai Science and Technology Development Funds(No.24CL2900500).
文摘Radiative cooling is a passive thermal management strategy that leverages the natural ability of materials to dissipate heat through infrared radiation.It has significant implications for energy efficiency,climate adaptation,and sustainable technology development,with applications in personal thermal management,building temperature regulation,and aerospace engineering.However,radiative cooling performance is susceptible to environmental aging and special environmental conditions,limiting its applicability in extreme environments.Herein,a critical review of extreme environmental radiative cooling is presented,focusing on enhancing environmental durability and cooling efficiency.This review first introduces the design principles of heat exchange channels,which are tailored based on the thermal flow equilibrium to optimize radiative cooling capacity in various extreme environments.Subsequently,recent advancements in radiative cooling materials and micronano structures that align with these principles are systematically discussed,with a focus on their implementation in terrestrial dwelling environments,terrestrial extreme environments,aeronautical environments,and space environments.Moreover,this review evaluates the cooling effects and anti-environmental abilities of extreme radiative cooling devices.Lastly,key challenges hindering the development of radiative cooling devices for extreme environmental applications are outlined,and potential strategies to overcome these limitations are proposed,aiming to prompt their future commercialization.
基金supported financially by the fund from the Ministry of Science and Technology of China(Grant No.2019YFB2205100)the National Science Fund for Distinguished Young Scholars(No.52025022)+3 种基金the National Nature Science Foundation of China(Grant Nos.U19A2091,62004016,51732003,52072065,1197407252272140 and 52372137)the‘111’Project(Grant No.B13013)the Fundamental Research Funds for the Central Universities(Nos.2412023YQ004 and 2412022QD036)the funding from Jilin Province(Grant Nos.20210201062GX,20220502002GH,20230402072GH,20230101017JC and 20210509045RQ)。
文摘Spiking neural network(SNN),widely known as the third-generation neural network,has been frequently investigated due to its excellent spatiotemporal information processing capability,high biological plausibility,and low energy consumption characteristics.Analogous to the working mechanism of human brain,the SNN system transmits information through the spiking action of neurons.Therefore,artificial neurons are critical building blocks for constructing SNN in hardware.Memristors are drawing growing attention due to low consumption,high speed,and nonlinearity characteristics,which are recently introduced to mimic the functions of biological neurons.Researchers have proposed multifarious memristive materials including organic materials,inorganic materials,or even two-dimensional materials.Taking advantage of the unique electrical behavior of these materials,several neuron models are successfully implemented,such as Hodgkin–Huxley model,leaky integrate-and-fire model and integrate-and-fire model.In this review,the recent reports of artificial neurons based on memristive devices are discussed.In addition,we highlight the models and applications through combining artificial neuronal devices with sensors or other electronic devices.Finally,the future challenges and outlooks of memristor-based artificial neurons are discussed,and the development of hardware implementation of brain-like intelligence system based on SNN is also prospected.
文摘This article studies the influence of the fineness of cement, fly ash(FA), its composite admixture and the amount and way mixed with superplasticizer on the rheological properties of micro fine cement(MC). By means of modern instruments and technologies (such as XRD, SEM, laser granulometer and superficial potential apparatus etc.), the article studies the mineral compositions, the appearance character of grains, particle size distribution and superficial potential of FA and its composite materials. And through that, the reducing mechanism of FA is thoroughly analyzed. The study shows that FA and its composite admixture are excellent components which can effectively improve the rheological properties of micro fine cement, and that the superplasticizer has a saturation point and the mixing way of it has a great influence on the rheological properties.
