In coal mining on a high-pressure Ordovician limestone aquifer,grouting materials should have sufficient mechanical properties,particularly strong interfacial bonding performance to address stress concentration at the...In coal mining on a high-pressure Ordovician limestone aquifer,grouting materials should have sufficient mechanical properties,particularly strong interfacial bonding performance to address stress concentration at the grout-limestone interface induced by rock stress disturbances during mining.In this study,graphene oxide(GO)was integrated into cement-polyacrylate composite grout to improve its interfacial bonding.First,four-point bending tests were conducted,and the Monte Carlo method combined with the simplex search algorithm was employed to determine the variations in shear cohesion and static friction parameters.The results reveal that GO can significantly increase both the tensile and shear cohesion of the grout-limestone interface,but minimally affects the interfacial friction coefficient.Second,nuclear magnetic resonance(NMR)and scanning electron microscopy(SEM)tests were performed.The results indicate that GO nanosheets result in a squamaceous microstructure of the grout consolidation mass,increasing the adhesion of the grout-limestone interface.Moreover,spiny Aft(ettringite)clusters can be induced in limestone fracture surfaces by GO,which could serve as anchors for limestone and grout consolidation mass.展开更多
This study aimed to address the challenges of solid waste utilization,cost reduction,and carbon reduction in the treatment of deep-dredged soil at Xuwei Port in Lianyungang city of China.Past research in this area was...This study aimed to address the challenges of solid waste utilization,cost reduction,and carbon reduction in the treatment of deep-dredged soil at Xuwei Port in Lianyungang city of China.Past research in this area was limited.Therefore,a curing agent made from powdered shells was used to solidify the dredged soil in situ.We employed laboratory orthogonal tests to investigate the physical and mechanical properties of the powdered shell-based curing agent.Data was collected by conducting experiments to assess the role of powdered shells in the curing process and to determine the optimal ratios of powdered shells to solidified soil for different purposes.The development of strength in solidified soil was studied in both seawater and pure water conditions.The study revealed that the strength of the solidified soil was influenced by the substitution rate of powdered shells and their interaction with cement.Higher cement content had a positive effect on strength.For high-strength solidified soil,the recommended ratio of wet soil:cement:lime:powdered shells were 100:16:4:4,while for low-strength solidified soil,the recommended ratio was 100:5.4:2.4:0.6.Seawater,under appropriate conditions,improved short-term strength by promoting the formation of expansive ettringite minerals that contributed to cementation and precipitation.These findings suggest that the combination of cement and powdered shells is synergistic,positively affecting the strength of solidified soil.The recommended ratios provide practical guidance for achieving desired strength levels while considering factors such as cost and carbon emissions.The role of seawater in enhancing short-term strength through crystal formation is noteworthy and can be advantageous for certain applications.In conclusion,this research demonstrates the potential of using a powdered shell-based curing agent for solidifying dredged soil in an environmentally friendly and cost-effective manner.The recommended ratios for different strength requirements offer valuable insights for practical applications in the field of soil treatment,contributing to sustainable and efficient solutions for soil management.展开更多
High-plastic clays with significant volume change due to moisture variations present critical challenges to civil engineering structures.Limestone calcined clay cement(LC3),an innovative and sustainable hydraulic bind...High-plastic clays with significant volume change due to moisture variations present critical challenges to civil engineering structures.Limestone calcined clay cement(LC3),an innovative and sustainable hydraulic binder,demonstrates significant potential for improving the engineering characteristics of such soils.Nevertheless,the impact of LC3 on the physico-mechanical characteristics of treated soil under a cyclic wet-dry environment remains unclear.This study for the first time investigates LC3's impact on the long-term durability of treated high-plastic clays through comprehensive macro-micro testing including physical,mechanical,mineralogical,and microstructural investigations with an emphasis on wet-dry cycles.The results revealed that LC3 treatment exhibits significant resistance to wet-dry cycles by completely mitigating the swelling potential,and a considerable reduction in plasticity resulting in enhanced workability.The compressibility and shear strength parameters have been significantly improved to several orders of magnitude.However,after six wet-dry cycles,a slight to modest reduction is observed,but overall durability remains superior to untreated soil.Cohesive and structural bonding ratios quantitatively assessed the impact of wet-dry cycles emphasizing the advantage of LC3 treatment.According to mineralogical and microstructural evaluation,the mechanism behind the adverse effects of wet-dry cycles on the compressibility and strength behavior of LC3-treated soil is mainly attributed to:(1)weakening of CSH/C(A)SH and ettringite(AFt)phases by exhibiting lower peak intensities;and(2)larger pore spaces due to repeated wet-dry cycles.These findings highlight LC3's performance in enhancing the long-term behavior and resilience of treated soils in real-world scenarios,providing durable solutions for infrastructure challenges.展开更多
This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The finding...This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The findings revealed that the addition of 5wt%CRCF yields optimal performance,with compressive strengths reaching approximately 1.83,12.59,and 42.81 MPa at 1,3,and 28 d,respectively.These values represented significant increases of 408.3%,10.0%,and 14.3%compared to the reference sample.The improvement was attributed to the synergistic effects of ultrafine CRCF particles acting as fillers and nucleation sites,as well as the high reactivity of silica gels,which promoted the formation of additional hydration gels.Microstructural analysis confirmed that CRCF addition refined pore structure,and enhanced the stiffness of C-S-H gels.Furthermore,CRCF served as a net CO_(2) sink,sequestering 0.268 kg CO_(2) per kilogram of CRCF and thereby reducing the carbon footprint of SSC.In addition,the feasibility of applying CRCF-modified SSC in cemented paste backfill(CPB)is highlighted,given the high cement-related carbon footprint of conventional CPB.When 5wt%CRCFmodified SSC was employed in CPB,its 3-d compressive strength attained over 70%of that of ordinary Portland cement(OPC),while the 28-d strength was comparable to that of OPC.The proposed binder thus provides a sustainable pathway for BW valorization,combining waste utilization,carbon sequestration,and improved engineering performance.展开更多
Cement stands as a dominant contributor to global energy consumption and carbon emissions in the construction industry.With the upgrading of infrastructure and the improvement of building standards,traditional cement ...Cement stands as a dominant contributor to global energy consumption and carbon emissions in the construction industry.With the upgrading of infrastructure and the improvement of building standards,traditional cement fails to reconcile ecological responsibility with advanced functional performance.By incorporating tailored fillers into cement matrices,the resulting composites achieve enhanced thermoelectric(TE)conversion capabilities.These materials can harness solar radiation from building envelopes and recover waste heat from indoor thermal gradients,facilitating bidirectional energy conversion.This review offers a comprehensive and timely overview of cementbased thermoelectric materials(CTEMs),integrating material design,device fabrication,and diverse applications into a holistic perspective.It summarizes recent advancements in TE performance enhancement,encompassing fillers optimization and matrices innovation.Additionally,the review consolidates fabrication strategies and performance evaluations of cement-based thermoelectric devices(CTEDs),providing detailed discussions on their roles in monitoring and protection,energy harvesting,and smart building.We also address sustainability,durability,and lifecycle considerations of CTEMs,which are essential for real-world deployment.Finally,we outline future research directions in materials design,device engineering,and scalable manufacturing to foster the practical application of CTEMs in sustainable and intelligent infrastructure.展开更多
Cemented paste backfill(CPB)is a technology that achieves safe mining by filling the goaf with waste rocks,tailings,and other materials.It is an inevitable choice to deal with the development of deep and highly diffic...Cemented paste backfill(CPB)is a technology that achieves safe mining by filling the goaf with waste rocks,tailings,and other materials.It is an inevitable choice to deal with the development of deep and highly difficult mines and meet the requirements of environmental protection and safety regulations.It promotes the development of a circular economy in mines through the development of lowgrade resources and the resource utilization of waste,and extends the service life of mines.The mass concentration of solid content(abbreviated as“concentration”)is a critical parameter for CPB.However,discrepancies often arise between the on-site measurements and the pre-designed values due to factors such as groundwater inflow and segregation within the goaf,which cannot be evaluated after the solidification of CPB.This paper innovatively provides an in-situ non-destructive approach to identify the real concentration of CPB after curing for certain days using hyperspectral imaging(HSI)technology.Initially,the spectral variation patterns under different concentration conditions were investigated through hyperspectral scanning experiments on CPB samples.The results demonstrate that as the CPB concentration increases from 61wt%to 73wt%,the overall spectral reflectance gradually increases,with two distinct absorption peaks observed at 1407 and 1917 nm.Notably,the reflectance at 1407 nm exhibited a strong linear relationship with the concentration.Subsequently,the K-nearest neighbors(KNN)and support vector machine(SVM)algorithms were employed to classify and identify different concentrations.The study revealed that,with the KNN algorithm,the highest accuracy was achieved when K(number of nearest neighbors)was 1,although this resulted in overfitting.When K=3,the model displayed the optimal balance between accuracy and stability,with an accuracy of 95.03%.In the SVM algorithm,the highest accuracy of 98.24%was attained with parameters C(regularization parameter)=200 and Gamma(kernel coefficient)=10.A comparative analysis of precision,accuracy,and recall further highlighted that the SVM provided superior stability and precision for identifying CPB concentration.Thus,HSI technology offers an effective solution for the in-situ,non-destructive monitoring of CPB concentration,presenting a promising approach for optimizing and controlling CPB characteristic parameters.展开更多
To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with g...To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.展开更多
Cement paste backfill(CPB)technology is a key method for mine waste treatment,and pipeline transport is critical for safe and efficient waste transfer.Variations in raw material properties can cause slurry segregation...Cement paste backfill(CPB)technology is a key method for mine waste treatment,and pipeline transport is critical for safe and efficient waste transfer.Variations in raw material properties can cause slurry segregation,increase pipeline wear and resistance,raise the risk of blockages or bursts,and disrupt operations.To study CPB slurry segregation during transport,CPB was prepared using cement as the cementitious material and unclassified tailings as inert materials.A small annular-tube device using an electrical resistance tomography system was developed to analyze its flow characteristics,and quantitative segregation assessment methods were developed.The results indicated that CPB conductivity increases with transport time but decreases with higher solid mass content,with the latter having a greater impact.At a low solid content,solid particles migrated toward the bottom of the pipe as the flow time increased,and the migratory behavior of the particles diminished as the solid content increased.At a flow rate of 1.25 m/s,the heterogeneity index for CPB with 58wt% solid content increased by 1.24 in 20 min,whereas that for CPB with 62wt% solid content increased by 2.17.Higher solid mass content amplifies the effect of conveying time on segregation,emphasizing the need to balance these factors for minimizing segregation.These insights can guide the optimization of mine pipeline transport systems.展开更多
The utilization of discarded coral debris in cementitious material is a prominent research area for island construction projects.The aim of this study is to explore the use of environment-friendly cement and waste cor...The utilization of discarded coral debris in cementitious material is a prominent research area for island construction projects.The aim of this study is to explore the use of environment-friendly cement and waste coral sand in the preparation of coral mortar,while investigating its performance when exposed to a chloride environment.Three types of low-carbon cements were employed,such as rapid hardening sulphoaluminate(RCSA)cement,high belite sulphoaluminate(HBCSA)cement,and slag sulphoaluminate cement(SSC).The coulomb electric flux,mechanical properties,free chloride content,and mass change of the cement mortar under exposed to 3.5 wt%NaCl solution were examined at various time intervals.X-ray diffraction analysis was conducted to identify the mineral phases present in the mortar samples.The results demonstrate that the flexural and compressive strength of the mortar consistently increase throughout the 360 days chloride exposure period.Incorporating coral sand into SSC-based mortars enhances their compressive strength from day 28 up until day 360.However,it adversely affects the strength of HBCSA-based mortars.The behavior of mortars exposed to a chloride-rich environment is closely associated with the amount of C-S-H gel present within them.SSC generates a significant quantity of C-S-H gel which possesses a large specific surface area capable of absorbing more chloride ions thereby reducing their concentration within the mortar matrix as well as increasing its mass and improving resistance against chloride ion penetration.展开更多
Improving energy efficiency and lowering negative environmental impact through waste heat recovery(WHR)is a critical step toward sustainable cement manufacturing.This study analyzes advanced cogeneration systems for r...Improving energy efficiency and lowering negative environmental impact through waste heat recovery(WHR)is a critical step toward sustainable cement manufacturing.This study analyzes advanced cogeneration systems for recovering waste heat from the Fallujah White Cement Plant in Iraq.The novelty of this work lies in its direct application and comparative thermodynamic analysis of three distinct cogeneration cycles—the Organic Rankine Cycle,the Single-Flash Steam Cycle,and the Dual-Pressure Steam Cycle—within the Iraqi cement industry,a context that has not been widely studied.The main objective is to evaluate and compare these models to determine the most effective approach for enhancing energy and exergy efficiencies.Themethodology involved detailed thermodynamic and exergy analyses of each system,supported by mathematical modelling and simulation using data from plant operations.The results reveal that the Dual-Pressure Steam Cycle emerged as the most effective system,delivering 13.76 MW of net power with a thermal efficiency of 32.8%and an exergy efficiency of 51%.This significantly outperformed the baseline Organic Rankine Cycle(8.18MW,18.8%thermal efficiency,30.7%exergy efficiency).These findings confirm that multipressure steam cycles offer a robust and practical solution for the Fallujah plant.This application provides a clear,high-impact pathway to enhance national industrial energy efficiency,significantly reduce CO_(2) emissions,and promote clean energy sustainability in Iraq.Future work should consider economic feasibility and potential integration with renewable energy sources to further enhance sustainability.展开更多
The influence mechanism of MgO particle fineness on the properties of MOC was comprehensively explored through means of grinding,sieving,hydration and apparent density testing,in conjunction with characterization meth...The influence mechanism of MgO particle fineness on the properties of MOC was comprehensively explored through means of grinding,sieving,hydration and apparent density testing,in conjunction with characterization methods such as setting time,stability,compressive strength,and microscopic morphology.The findings reveal that MOC demonstrates excellent stability and mechanical properties when the particle fineness of MgO is less than 75μm.When the MgO particle fineness exceeds 75μm,MOC exhibits superior fluidity and maneuverability.When 0.75μm MgO is employed as the raw material to prepare MOC,a water-cement ratio of 0.6 proves more favorable.These results can furnish a theoretical foundation for the preparation and application of MOC.展开更多
Chlorite coats are believed to inhibit quartz cementation and preserve deeply-buried sandstone porosity.However,geologists face numerous challenges in evaluating the influences of chlorite coats in real cases.To tackl...Chlorite coats are believed to inhibit quartz cementation and preserve deeply-buried sandstone porosity.However,geologists face numerous challenges in evaluating the influences of chlorite coats in real cases.To tackle these challenges,this work reviewed a large number of case studies to discuss the proper way to evaluate their role using petrography.The following five main conclusions were drawn:(1)Compared to other coat parameters,coat coverage is more reliable in evaluating the influence of chlorite coats on quartz cements.(2)In addition to chlorite coats,quartz growth is influenced by multiple factors such as temperature,while sandstone porosity is affected by various factors including mechanical compaction;therefore,when evaluating the influence of chlorite coats,geologists should take these factors into account.(3)Even if no negative correlation exists between chlorite coats and quartz cements,and no positive correlation is observed between chlorite coats and sandstone porosity,one cannot simply conclude that chlorite coats do not inhibit quartz cements and protect sandstone porosity.(4)Chlorite coats can significantly occupy pore space,leading to a net porosity decrease.(5)Chlorite coats can undergo significantly dissolution,while whether this phenomenon is ubiquitous remains underexplored.展开更多
Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipmen...Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipment manufacturing,and electronic information.This review provides a comprehensive summary of the progress of AM technology in WC−Co cemented carbides.The fundamental principles and classification of AM techniques are introduced,followed by a categorization and evaluation of the AM techniques for WC−Co cemented carbides.These techniques are classified as either direct AM technology(DAM)or indirect AM technology(IDAM),depending on their inclusion of post-processes like de-binding and sintering.Through an analysis of microstructure features,the most suitable AM route for WC−Co cemented carbide products with controllable microstructure is identified as the indirect AM technology,such as binder jet printing(BJP),which integrates AM with conventional powder metallurgy.展开更多
As underground mining advances to greater depths,cemented paste backfill(CPB)is increasingly subjected to complex thermo-mechanical loading conditions,including multiaxial stress states and elevated temperatures.This ...As underground mining advances to greater depths,cemented paste backfill(CPB)is increasingly subjected to complex thermo-mechanical loading conditions,including multiaxial stress states and elevated temperatures.This study investigates the coupled effects of field-representative vertical self-weight and horizontal rockwall closure stresses,along with in-situ temperatures,on the mechanical behavior and pore water pressure(PWP)evolution of CPB.Experiments were conducted using a novel apparatus capable of controlling multiaxial stress and temperature during curing,replicating in-situ stress paths and thermal profiles typical of deep mine environments.Results show that multiaxial stress enhances CPB strength and stiffness by promoting denser particle packing,reducing porosity,and increasing frictional resistance.Elevated temperatures independently accelerate early-age cement hydration,further improving bond strength and stiffness.When combined,multiaxial stress and elevated temperature produce a synergistic enhancement in unconfined compressive strength(UCS)and elastic modulus,as confirmed by two-way ANOVA and synergy index analysis.PWP responses were also highly sensitive to thermo-mechanical conditions.The evolution of positive and negative PWP was governed by the interplay of thermal expansion,hydration-induced desaturation,and mechanical compaction.Multiaxial stress amplified early positive PWP and delayed its dissipation,whereas elevated temperature accelerated hydration and reduced pore pressure,leading to enhanced suction at later ages.A transient“stress-induced resaturation”effect was observed under late-stage excessive horizontal stress but was mitigated by elevated temperatures.These findings provide critical insights into the coupled mechanical and hydraulic behavior of CPB under realistic field conditions and offer guidance for optimizing backfill design,binder content,and barricade stability in deep mining applications.展开更多
Cemented rockfill(CRF)combines structural support with sustainable reuse of coal-derived solid waste.This study integrates digital image correlation,acoustic emission monitoring,and finite-discrete element simulations...Cemented rockfill(CRF)combines structural support with sustainable reuse of coal-derived solid waste.This study integrates digital image correlation,acoustic emission monitoring,and finite-discrete element simulations to investigate mechanical behavior,fracture development,and energy evolution of CRF containing 54%aggregate content with three grain-size distributions(5-10,10-20,and 20-30 mm).Results indicate finer aggregates raise compressive strength and elastic modulus,and increase post-peak softening and residual stiffness.Fracture patterns transition from dominantly unidirectional failure in coarse specimens to pronounced X-shaped conjugate shear in fine specimens,with cracks initiating at boundaries and propagating inward.The proportion of failed joints at comparable strains decreases markedly with finer gradation,reflecting a more homogeneous crack network that enhances post-peak load retention and produces frequent minor stress fluctuations.Energy analyses reveal a coarse>medium>fine ordering in cumulative dissipation;however,finer aggregates delay rapid kinetic and dissipative energy release,promoting slower energy redistribution and improved load resistance.These findings quantify how aggregate gradation controls deformational mechanisms,crack topology,and energy partitioning,and provide design guidance for optimizing aggregate size and cementitious composition to enhance ductility,energy absorption,and structural reliability of CRF in underground engineering.展开更多
High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under c...High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under conditions of high ground temperature and unloading by conducting triaxial unloading tests with different initial confining pressures on CGFB that had been cured at various temperatures.Based on dissipative energy,triaxial unloading confining pressure damage constitutive model of CGFB was constructed.It has been demonstrated that the ratio of elastic strain energy in CGFB decreases and the ratio of dissipated energy increases at the end of unloading increases under higher curing temperature.The change in the elastic energy consumption ratio curve of CGFB,which shifts from a gradual increase to a swift rise at a certain"inflection point",can be utilized as a criterion for evaluating the failure of the unloading strength of CGFB.The triaxial unloading damage constitutive model for CGFB divides the damage progression into three distinct phases:initial damage stage,accelerated damage development stage,and rapid damage growth stage.The research findings offer a theoretical foundation for evaluating the extent of damage to CGFB caused by the combined influences of elevated ground temperature and unloading.展开更多
The cemented tailings backfill(CTB)with initial defects is more prone to destabilization damage under the influence of various unfavorable factors during the mining process.In order to investigate its influence on the...The cemented tailings backfill(CTB)with initial defects is more prone to destabilization damage under the influence of various unfavorable factors during the mining process.In order to investigate its influence on the stability of underground mining engineering,this paper simulates the generation of different degrees of initial defects inside the CTB by adding different contents of air-entraining agent(AEA),investigates the acoustic emission RA/AF eigenvalues of CTB with different contents of AEA under uniaxial compression,and adopts various denoising algorithms(e.g.,moving average smoothing,median filtering,and outlier detection)to improve the accuracy of the data.The variance and autocorrelation coefficients of RA/AF parameters were analyzed in conjunction with the critical slowing down(CSD)theory.The results show that the acoustic emission RA/AF values can be used to characterize the progressive damage evolution of CTB.The denoising algorithm processed the AE signals to reduce the effects of extraneous noise and anomalous spikes.Changes in the variance curves provide clear precursor information,while abrupt changes in the autocorrelation coefficient can be used as an auxiliary localization warning signal.The phenomenon of dramatic increase in the variance and autocorrelation coefficient curves during the compression-tightening stage,which is influenced by the initial defects,can lead to false warnings.As the initial defects of the CTB increase,its instability precursor time and instability time are prolonged,the peak stress decreases,and the time difference between the CTB and the instability damage is smaller.The results provide a new method for real-time monitoring and early warning of CTB instability damage.展开更多
The consolidation behavior of mixed in place cement and lime/cement mixed column was studied. Consolidation of the composite foundation was modeled as a three dimensional axi symmetric problem. The authors used t...The consolidation behavior of mixed in place cement and lime/cement mixed column was studied. Consolidation of the composite foundation was modeled as a three dimensional axi symmetric problem. The authors used the finite difference method to obtain the pore pressure variation with time at any location below the surface. A computer program developed by the authors was used to draw some interesting conclusions about the consolidation behaviors of cement and lime/cement mixed pile foundation. Finally, a combined model including the permeability coefficients of cement mixed piles and soil, was studied and its feasibility was evaluated.展开更多
基金supported by the National Key R&D Program of China(Grant Nos.U25A20810 and 2024YFF0508201)the National Natural Science Foundation of China(Grant No.12302504).
文摘In coal mining on a high-pressure Ordovician limestone aquifer,grouting materials should have sufficient mechanical properties,particularly strong interfacial bonding performance to address stress concentration at the grout-limestone interface induced by rock stress disturbances during mining.In this study,graphene oxide(GO)was integrated into cement-polyacrylate composite grout to improve its interfacial bonding.First,four-point bending tests were conducted,and the Monte Carlo method combined with the simplex search algorithm was employed to determine the variations in shear cohesion and static friction parameters.The results reveal that GO can significantly increase both the tensile and shear cohesion of the grout-limestone interface,but minimally affects the interfacial friction coefficient.Second,nuclear magnetic resonance(NMR)and scanning electron microscopy(SEM)tests were performed.The results indicate that GO nanosheets result in a squamaceous microstructure of the grout consolidation mass,increasing the adhesion of the grout-limestone interface.Moreover,spiny Aft(ettringite)clusters can be induced in limestone fracture surfaces by GO,which could serve as anchors for limestone and grout consolidation mass.
基金Funded by the Science and Technology Project of Jiangsu Provincial Transportation Department(No.2022Y13)。
文摘This study aimed to address the challenges of solid waste utilization,cost reduction,and carbon reduction in the treatment of deep-dredged soil at Xuwei Port in Lianyungang city of China.Past research in this area was limited.Therefore,a curing agent made from powdered shells was used to solidify the dredged soil in situ.We employed laboratory orthogonal tests to investigate the physical and mechanical properties of the powdered shell-based curing agent.Data was collected by conducting experiments to assess the role of powdered shells in the curing process and to determine the optimal ratios of powdered shells to solidified soil for different purposes.The development of strength in solidified soil was studied in both seawater and pure water conditions.The study revealed that the strength of the solidified soil was influenced by the substitution rate of powdered shells and their interaction with cement.Higher cement content had a positive effect on strength.For high-strength solidified soil,the recommended ratio of wet soil:cement:lime:powdered shells were 100:16:4:4,while for low-strength solidified soil,the recommended ratio was 100:5.4:2.4:0.6.Seawater,under appropriate conditions,improved short-term strength by promoting the formation of expansive ettringite minerals that contributed to cementation and precipitation.These findings suggest that the combination of cement and powdered shells is synergistic,positively affecting the strength of solidified soil.The recommended ratios provide practical guidance for achieving desired strength levels while considering factors such as cost and carbon emissions.The role of seawater in enhancing short-term strength through crystal formation is noteworthy and can be advantageous for certain applications.In conclusion,this research demonstrates the potential of using a powdered shell-based curing agent for solidifying dredged soil in an environmentally friendly and cost-effective manner.The recommended ratios for different strength requirements offer valuable insights for practical applications in the field of soil treatment,contributing to sustainable and efficient solutions for soil management.
基金The financial support of the National Natural Science Foundation of China(Grant No.42030714)the National Key R&D Program of China(Grant No.2019YFC1509900)is greatly acknowledged.
文摘High-plastic clays with significant volume change due to moisture variations present critical challenges to civil engineering structures.Limestone calcined clay cement(LC3),an innovative and sustainable hydraulic binder,demonstrates significant potential for improving the engineering characteristics of such soils.Nevertheless,the impact of LC3 on the physico-mechanical characteristics of treated soil under a cyclic wet-dry environment remains unclear.This study for the first time investigates LC3's impact on the long-term durability of treated high-plastic clays through comprehensive macro-micro testing including physical,mechanical,mineralogical,and microstructural investigations with an emphasis on wet-dry cycles.The results revealed that LC3 treatment exhibits significant resistance to wet-dry cycles by completely mitigating the swelling potential,and a considerable reduction in plasticity resulting in enhanced workability.The compressibility and shear strength parameters have been significantly improved to several orders of magnitude.However,after six wet-dry cycles,a slight to modest reduction is observed,but overall durability remains superior to untreated soil.Cohesive and structural bonding ratios quantitatively assessed the impact of wet-dry cycles emphasizing the advantage of LC3 treatment.According to mineralogical and microstructural evaluation,the mechanism behind the adverse effects of wet-dry cycles on the compressibility and strength behavior of LC3-treated soil is mainly attributed to:(1)weakening of CSH/C(A)SH and ettringite(AFt)phases by exhibiting lower peak intensities;and(2)larger pore spaces due to repeated wet-dry cycles.These findings highlight LC3's performance in enhancing the long-term behavior and resilience of treated soils in real-world scenarios,providing durable solutions for infrastructure challenges.
基金supports from the National Natural Science Foundation of China(No.52304148)the Youth Project of Shanxi Basic Research Program(No.202203021212262).
文摘This study investigates the performance enhancement of super-sulfated cement(SSC)derived from arsenic-containing bio-oxidation waste(BW)through the incorporation of carbonated recycled concrete fines(CRCF).The findings revealed that the addition of 5wt%CRCF yields optimal performance,with compressive strengths reaching approximately 1.83,12.59,and 42.81 MPa at 1,3,and 28 d,respectively.These values represented significant increases of 408.3%,10.0%,and 14.3%compared to the reference sample.The improvement was attributed to the synergistic effects of ultrafine CRCF particles acting as fillers and nucleation sites,as well as the high reactivity of silica gels,which promoted the formation of additional hydration gels.Microstructural analysis confirmed that CRCF addition refined pore structure,and enhanced the stiffness of C-S-H gels.Furthermore,CRCF served as a net CO_(2) sink,sequestering 0.268 kg CO_(2) per kilogram of CRCF and thereby reducing the carbon footprint of SSC.In addition,the feasibility of applying CRCF-modified SSC in cemented paste backfill(CPB)is highlighted,given the high cement-related carbon footprint of conventional CPB.When 5wt%CRCFmodified SSC was employed in CPB,its 3-d compressive strength attained over 70%of that of ordinary Portland cement(OPC),while the 28-d strength was comparable to that of OPC.The proposed binder thus provides a sustainable pathway for BW valorization,combining waste utilization,carbon sequestration,and improved engineering performance.
基金supported by the National Natural Science Foundation of China(No.52242305).
文摘Cement stands as a dominant contributor to global energy consumption and carbon emissions in the construction industry.With the upgrading of infrastructure and the improvement of building standards,traditional cement fails to reconcile ecological responsibility with advanced functional performance.By incorporating tailored fillers into cement matrices,the resulting composites achieve enhanced thermoelectric(TE)conversion capabilities.These materials can harness solar radiation from building envelopes and recover waste heat from indoor thermal gradients,facilitating bidirectional energy conversion.This review offers a comprehensive and timely overview of cementbased thermoelectric materials(CTEMs),integrating material design,device fabrication,and diverse applications into a holistic perspective.It summarizes recent advancements in TE performance enhancement,encompassing fillers optimization and matrices innovation.Additionally,the review consolidates fabrication strategies and performance evaluations of cement-based thermoelectric devices(CTEDs),providing detailed discussions on their roles in monitoring and protection,energy harvesting,and smart building.We also address sustainability,durability,and lifecycle considerations of CTEMs,which are essential for real-world deployment.Finally,we outline future research directions in materials design,device engineering,and scalable manufacturing to foster the practical application of CTEMs in sustainable and intelligent infrastructure.
基金funded by the National Natural Science Foundation of China(Nos.52474165 and 52522404)。
文摘Cemented paste backfill(CPB)is a technology that achieves safe mining by filling the goaf with waste rocks,tailings,and other materials.It is an inevitable choice to deal with the development of deep and highly difficult mines and meet the requirements of environmental protection and safety regulations.It promotes the development of a circular economy in mines through the development of lowgrade resources and the resource utilization of waste,and extends the service life of mines.The mass concentration of solid content(abbreviated as“concentration”)is a critical parameter for CPB.However,discrepancies often arise between the on-site measurements and the pre-designed values due to factors such as groundwater inflow and segregation within the goaf,which cannot be evaluated after the solidification of CPB.This paper innovatively provides an in-situ non-destructive approach to identify the real concentration of CPB after curing for certain days using hyperspectral imaging(HSI)technology.Initially,the spectral variation patterns under different concentration conditions were investigated through hyperspectral scanning experiments on CPB samples.The results demonstrate that as the CPB concentration increases from 61wt%to 73wt%,the overall spectral reflectance gradually increases,with two distinct absorption peaks observed at 1407 and 1917 nm.Notably,the reflectance at 1407 nm exhibited a strong linear relationship with the concentration.Subsequently,the K-nearest neighbors(KNN)and support vector machine(SVM)algorithms were employed to classify and identify different concentrations.The study revealed that,with the KNN algorithm,the highest accuracy was achieved when K(number of nearest neighbors)was 1,although this resulted in overfitting.When K=3,the model displayed the optimal balance between accuracy and stability,with an accuracy of 95.03%.In the SVM algorithm,the highest accuracy of 98.24%was attained with parameters C(regularization parameter)=200 and Gamma(kernel coefficient)=10.A comparative analysis of precision,accuracy,and recall further highlighted that the SVM provided superior stability and precision for identifying CPB concentration.Thus,HSI technology offers an effective solution for the in-situ,non-destructive monitoring of CPB concentration,presenting a promising approach for optimizing and controlling CPB characteristic parameters.
基金Funded by the National Natural Science Foundation of China(Nos.5226804252468035)。
文摘To investigate the pore structure of graphene oxide modified polymer cement mortar(GOPM)under salt-freeze-thaw(SFT)coupling effects and its impact on deterioration,this study modifies polymer cement mortar(EMCM)with graphene oxide(GO).The micro-pore structure of GOPM is characterized using LF-NMR and SEM.Fractal theory is applied to calculate the fractal dimension of pore volume,and the deterioration patterns are analyzed based on the evolution characteristics of capillary pores.The experimental results indicate that,after 25 salt-freeze-thaw cycles(SFTc),SO2-4 ions penetrate the matrix,generating corrosion products that fill existing pores and enhance the compactness of the specimen.As the number of cycles increases,the ongoing formation and expansion of corrosion products within the matrix,combined with persistent freezing forces,and result in the degradation of the pore structure.Therefore,the mass loss rate(MLR)of the specimens shows a trend of first decreasing and then increasing,while the relative dynamic elastic modulus(RDEM)initially increases and then decreases.Compared to the PC group specimens,the G3PM group specimens show a 28.71% reduction in MLR and a 31.42% increase in RDEM after 150 SFTc.The fractal dimensions of the transition pores,capillary pores,and macropores in the G3PM specimens first increase and then decrease as the number of SFTc increases.Among them,the capillary pores show the highest correlation with MLR and RDEM,with correlation coefficients of 0.97438 and 0.98555,respectively.
基金supported by the National Natural ScienceFoundation of China(Nos.52427804 and 52574136).
文摘Cement paste backfill(CPB)technology is a key method for mine waste treatment,and pipeline transport is critical for safe and efficient waste transfer.Variations in raw material properties can cause slurry segregation,increase pipeline wear and resistance,raise the risk of blockages or bursts,and disrupt operations.To study CPB slurry segregation during transport,CPB was prepared using cement as the cementitious material and unclassified tailings as inert materials.A small annular-tube device using an electrical resistance tomography system was developed to analyze its flow characteristics,and quantitative segregation assessment methods were developed.The results indicated that CPB conductivity increases with transport time but decreases with higher solid mass content,with the latter having a greater impact.At a low solid content,solid particles migrated toward the bottom of the pipe as the flow time increased,and the migratory behavior of the particles diminished as the solid content increased.At a flow rate of 1.25 m/s,the heterogeneity index for CPB with 58wt% solid content increased by 1.24 in 20 min,whereas that for CPB with 62wt% solid content increased by 2.17.Higher solid mass content amplifies the effect of conveying time on segregation,emphasizing the need to balance these factors for minimizing segregation.These insights can guide the optimization of mine pipeline transport systems.
基金Funded by the National Natural Science Foundation of China(No.51708290)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘The utilization of discarded coral debris in cementitious material is a prominent research area for island construction projects.The aim of this study is to explore the use of environment-friendly cement and waste coral sand in the preparation of coral mortar,while investigating its performance when exposed to a chloride environment.Three types of low-carbon cements were employed,such as rapid hardening sulphoaluminate(RCSA)cement,high belite sulphoaluminate(HBCSA)cement,and slag sulphoaluminate cement(SSC).The coulomb electric flux,mechanical properties,free chloride content,and mass change of the cement mortar under exposed to 3.5 wt%NaCl solution were examined at various time intervals.X-ray diffraction analysis was conducted to identify the mineral phases present in the mortar samples.The results demonstrate that the flexural and compressive strength of the mortar consistently increase throughout the 360 days chloride exposure period.Incorporating coral sand into SSC-based mortars enhances their compressive strength from day 28 up until day 360.However,it adversely affects the strength of HBCSA-based mortars.The behavior of mortars exposed to a chloride-rich environment is closely associated with the amount of C-S-H gel present within them.SSC generates a significant quantity of C-S-H gel which possesses a large specific surface area capable of absorbing more chloride ions thereby reducing their concentration within the mortar matrix as well as increasing its mass and improving resistance against chloride ion penetration.
文摘Improving energy efficiency and lowering negative environmental impact through waste heat recovery(WHR)is a critical step toward sustainable cement manufacturing.This study analyzes advanced cogeneration systems for recovering waste heat from the Fallujah White Cement Plant in Iraq.The novelty of this work lies in its direct application and comparative thermodynamic analysis of three distinct cogeneration cycles—the Organic Rankine Cycle,the Single-Flash Steam Cycle,and the Dual-Pressure Steam Cycle—within the Iraqi cement industry,a context that has not been widely studied.The main objective is to evaluate and compare these models to determine the most effective approach for enhancing energy and exergy efficiencies.Themethodology involved detailed thermodynamic and exergy analyses of each system,supported by mathematical modelling and simulation using data from plant operations.The results reveal that the Dual-Pressure Steam Cycle emerged as the most effective system,delivering 13.76 MW of net power with a thermal efficiency of 32.8%and an exergy efficiency of 51%.This significantly outperformed the baseline Organic Rankine Cycle(8.18MW,18.8%thermal efficiency,30.7%exergy efficiency).These findings confirm that multipressure steam cycles offer a robust and practical solution for the Fallujah plant.This application provides a clear,high-impact pathway to enhance national industrial energy efficiency,significantly reduce CO_(2) emissions,and promote clean energy sustainability in Iraq.Future work should consider economic feasibility and potential integration with renewable energy sources to further enhance sustainability.
基金Funded by the Ten National-level Science and Technology Innovation Platform Cultivation and Construction Projects in Qinghai Province(No.2025-ZJ-J01)the Leader of Natural Science and Engineering Technology in Qinghai Province(2023)the Western Young Scholars Program of Chinese Academy of Sciences(2024)。
文摘The influence mechanism of MgO particle fineness on the properties of MOC was comprehensively explored through means of grinding,sieving,hydration and apparent density testing,in conjunction with characterization methods such as setting time,stability,compressive strength,and microscopic morphology.The findings reveal that MOC demonstrates excellent stability and mechanical properties when the particle fineness of MgO is less than 75μm.When the MgO particle fineness exceeds 75μm,MOC exhibits superior fluidity and maneuverability.When 0.75μm MgO is employed as the raw material to prepare MOC,a water-cement ratio of 0.6 proves more favorable.These results can furnish a theoretical foundation for the preparation and application of MOC.
基金financially supported by the Hubei Provincial 100-Talent Program 2025National Natural Science Foundation of China(No.42502111)+2 种基金National Postdoctoral Researchers Program(No.GZC20250293)China Postdoctoral Science Foundation(No.2025M770446)Melbourne Research Scholarship(No.396349)。
文摘Chlorite coats are believed to inhibit quartz cementation and preserve deeply-buried sandstone porosity.However,geologists face numerous challenges in evaluating the influences of chlorite coats in real cases.To tackle these challenges,this work reviewed a large number of case studies to discuss the proper way to evaluate their role using petrography.The following five main conclusions were drawn:(1)Compared to other coat parameters,coat coverage is more reliable in evaluating the influence of chlorite coats on quartz cements.(2)In addition to chlorite coats,quartz growth is influenced by multiple factors such as temperature,while sandstone porosity is affected by various factors including mechanical compaction;therefore,when evaluating the influence of chlorite coats,geologists should take these factors into account.(3)Even if no negative correlation exists between chlorite coats and quartz cements,and no positive correlation is observed between chlorite coats and sandstone porosity,one cannot simply conclude that chlorite coats do not inhibit quartz cements and protect sandstone porosity.(4)Chlorite coats can significantly occupy pore space,leading to a net porosity decrease.(5)Chlorite coats can undergo significantly dissolution,while whether this phenomenon is ubiquitous remains underexplored.
基金supported by Major Science and Technology Projects in Fujian Province,China(No.2023HZ021005)State Key Laboratory of Powder Metallurgy,Central South University,ChinaFujian Key Laboratory of Rare-earth Functional Materials,China。
文摘Additive manufacturing(AM)technology has emerged as a viable solution for manufacturing complexshaped WC−Co cemented carbide products,thereby expanding their applications in industries such as resource mining,equipment manufacturing,and electronic information.This review provides a comprehensive summary of the progress of AM technology in WC−Co cemented carbides.The fundamental principles and classification of AM techniques are introduced,followed by a categorization and evaluation of the AM techniques for WC−Co cemented carbides.These techniques are classified as either direct AM technology(DAM)or indirect AM technology(IDAM),depending on their inclusion of post-processes like de-binding and sintering.Through an analysis of microstructure features,the most suitable AM route for WC−Co cemented carbide products with controllable microstructure is identified as the indirect AM technology,such as binder jet printing(BJP),which integrates AM with conventional powder metallurgy.
基金the University of Ottawa, the China Scholarship Council and the Natural Sciences and Engineering Research Council of Canada (NSERC) for their financial support.
文摘As underground mining advances to greater depths,cemented paste backfill(CPB)is increasingly subjected to complex thermo-mechanical loading conditions,including multiaxial stress states and elevated temperatures.This study investigates the coupled effects of field-representative vertical self-weight and horizontal rockwall closure stresses,along with in-situ temperatures,on the mechanical behavior and pore water pressure(PWP)evolution of CPB.Experiments were conducted using a novel apparatus capable of controlling multiaxial stress and temperature during curing,replicating in-situ stress paths and thermal profiles typical of deep mine environments.Results show that multiaxial stress enhances CPB strength and stiffness by promoting denser particle packing,reducing porosity,and increasing frictional resistance.Elevated temperatures independently accelerate early-age cement hydration,further improving bond strength and stiffness.When combined,multiaxial stress and elevated temperature produce a synergistic enhancement in unconfined compressive strength(UCS)and elastic modulus,as confirmed by two-way ANOVA and synergy index analysis.PWP responses were also highly sensitive to thermo-mechanical conditions.The evolution of positive and negative PWP was governed by the interplay of thermal expansion,hydration-induced desaturation,and mechanical compaction.Multiaxial stress amplified early positive PWP and delayed its dissipation,whereas elevated temperature accelerated hydration and reduced pore pressure,leading to enhanced suction at later ages.A transient“stress-induced resaturation”effect was observed under late-stage excessive horizontal stress but was mitigated by elevated temperatures.These findings provide critical insights into the coupled mechanical and hydraulic behavior of CPB under realistic field conditions and offer guidance for optimizing backfill design,binder content,and barricade stability in deep mining applications.
基金funding from the National Natural Science Foundation of China(Nos.52478389 and 52525401).
文摘Cemented rockfill(CRF)combines structural support with sustainable reuse of coal-derived solid waste.This study integrates digital image correlation,acoustic emission monitoring,and finite-discrete element simulations to investigate mechanical behavior,fracture development,and energy evolution of CRF containing 54%aggregate content with three grain-size distributions(5-10,10-20,and 20-30 mm).Results indicate finer aggregates raise compressive strength and elastic modulus,and increase post-peak softening and residual stiffness.Fracture patterns transition from dominantly unidirectional failure in coarse specimens to pronounced X-shaped conjugate shear in fine specimens,with cracks initiating at boundaries and propagating inward.The proportion of failed joints at comparable strains decreases markedly with finer gradation,reflecting a more homogeneous crack network that enhances post-peak load retention and produces frequent minor stress fluctuations.Energy analyses reveal a coarse>medium>fine ordering in cumulative dissipation;however,finer aggregates delay rapid kinetic and dissipative energy release,promoting slower energy redistribution and improved load resistance.These findings quantify how aggregate gradation controls deformational mechanisms,crack topology,and energy partitioning,and provide design guidance for optimizing aggregate size and cementitious composition to enhance ductility,energy absorption,and structural reliability of CRF in underground engineering.
基金Project(2024YFC2911000)supported by the National Key Research and Development Program Young Scientist Project,ChinaProject(2022HWYQ-078)supported by the Natural Science Foundation of Shandong Province of China+1 种基金Project(tsqn202103074)supported by the"Taishan Scholars Young Expert Program"of Shandong Province,ChinaProject(2023GX051)supported by the Tai'an Science and Technology Innovation Development Project(Policy Guidance),China。
文摘High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under conditions of high ground temperature and unloading by conducting triaxial unloading tests with different initial confining pressures on CGFB that had been cured at various temperatures.Based on dissipative energy,triaxial unloading confining pressure damage constitutive model of CGFB was constructed.It has been demonstrated that the ratio of elastic strain energy in CGFB decreases and the ratio of dissipated energy increases at the end of unloading increases under higher curing temperature.The change in the elastic energy consumption ratio curve of CGFB,which shifts from a gradual increase to a swift rise at a certain"inflection point",can be utilized as a criterion for evaluating the failure of the unloading strength of CGFB.The triaxial unloading damage constitutive model for CGFB divides the damage progression into three distinct phases:initial damage stage,accelerated damage development stage,and rapid damage growth stage.The research findings offer a theoretical foundation for evaluating the extent of damage to CGFB caused by the combined influences of elevated ground temperature and unloading.
基金Projects(52374138,51764013)supported by the National Natural Science Foundation of ChinaProject(20204BCJ22005)supported by the Training Plan for Academic and Technical Leaders of Major Disciplines of Jiangxi Province,China+1 种基金Project(2019M652277)supported by the China Postdoctoral Science FoundationProject(20192ACBL21014)supported by the Natural Science Youth Foundation Key Projects of Jiangxi Province,China。
文摘The cemented tailings backfill(CTB)with initial defects is more prone to destabilization damage under the influence of various unfavorable factors during the mining process.In order to investigate its influence on the stability of underground mining engineering,this paper simulates the generation of different degrees of initial defects inside the CTB by adding different contents of air-entraining agent(AEA),investigates the acoustic emission RA/AF eigenvalues of CTB with different contents of AEA under uniaxial compression,and adopts various denoising algorithms(e.g.,moving average smoothing,median filtering,and outlier detection)to improve the accuracy of the data.The variance and autocorrelation coefficients of RA/AF parameters were analyzed in conjunction with the critical slowing down(CSD)theory.The results show that the acoustic emission RA/AF values can be used to characterize the progressive damage evolution of CTB.The denoising algorithm processed the AE signals to reduce the effects of extraneous noise and anomalous spikes.Changes in the variance curves provide clear precursor information,while abrupt changes in the autocorrelation coefficient can be used as an auxiliary localization warning signal.The phenomenon of dramatic increase in the variance and autocorrelation coefficient curves during the compression-tightening stage,which is influenced by the initial defects,can lead to false warnings.As the initial defects of the CTB increase,its instability precursor time and instability time are prolonged,the peak stress decreases,and the time difference between the CTB and the instability damage is smaller.The results provide a new method for real-time monitoring and early warning of CTB instability damage.
文摘The consolidation behavior of mixed in place cement and lime/cement mixed column was studied. Consolidation of the composite foundation was modeled as a three dimensional axi symmetric problem. The authors used the finite difference method to obtain the pore pressure variation with time at any location below the surface. A computer program developed by the authors was used to draw some interesting conclusions about the consolidation behaviors of cement and lime/cement mixed pile foundation. Finally, a combined model including the permeability coefficients of cement mixed piles and soil, was studied and its feasibility was evaluated.
