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
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
The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change,a key component of which is carbon capture,utilization,and storage(CCUS)technology.Despite its importance,th...The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change,a key component of which is carbon capture,utilization,and storage(CCUS)technology.Despite its importance,there is a lack of empirical assessments of early opportunities for CCUS implementation in the cement sector.In this study,a comprehensive onshore and offshore source–sink matching optimization assessment framework for CCUS retrofitting in the cement industry,called the SSM-Cement framework,is proposed.The framework comprises four main modules:the cement plant suitability screening module,the storage site assessment module,the source–sink matching optimization model module,and the economic assessment module.By applying this framework to China,919 candidates are initially screened from 1132 existing cement plants.Further,603 CCUS-ready cement plants are identified,and are found to achieve a cumulative emission reduction of 18.5 Gt CO_(2) from 2030 to 2060 by meeting the CCUS feasibility conditions for constructing both onshore and offshore CO_(2) transportation routes.The levelized cost of cement(LCOC)is found to range from 30 to 96(mean 73)USD·(t cement)^(-1),while the levelized carbon avoidance cost(LCAC)ranges from^(-5) to 140(mean 88)USD·(t CO_(2))^(-1).The northeastern and northwestern regions of China are considered priority areas for CCUS implementation,with the LCAC concentrated in the range of 35 to 70 USD·(t CO_(2))^(-1).In addition to onshore storage of 15.8 Gt CO_(2) from 2030 to 2060,offshore storage would contribute 2.7 Gt of decarbonization for coastal cement plants,with comparable LCACs around 90 USD·(t CO_(2))^(-1).展开更多
The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr mul...The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr multi-principal-element alloy(MPEA)binder,has been investigated by performing sliding wear tests and composition characterization.The results showed that compared with CC,FGCC had higher hardness,stronger fracture toughness,better wear performance,and similar TRS.FGCCs exhibited lower wear rates(3.44×10^(−7)–6.95×10^(−6)mm^(3)/(N m))and coefficients of friction(COFs)(0.27–0.39)than CCs from RT to 600℃due to mitigation of multiple risks caused by binder removal,fragmentation and pull-out of WC grains,high-temperature oxidation and softening.In the low-temperature wear stage,the MPEA binder underwent dynamic recrystallization(DRX)and twinning deformation before removing from the surface.The binder removal caused dislocation pile-ups and stacking faults(SFs)to form under high stress,resulting in fragmentation and pull-out of WC grains.The low-temperature wear was dominated by abrasive wear and adhesive wear,with a low wear rate and a high and unstable COF.In the high-temperature wear stage,initial pitting oxidation of WC grains generated many subgrain boundaries,reducing heat transfer and exacerbating oxidation,resulting in an oxide layer enriched with WO3,Mx Oy,and MWO4.High-temperature wear was dominated by oxidation wear and high-temperature softening,with a high wear rate and a low and smooth COF.The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr,but also a new approach for the preparation of cemented carbides with high wear resistance.展开更多
Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the...Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.展开更多
Weak cementation between natural gas hydrates and mud–sand seriously affects the solid-fluidized mining of natural gas hydrates. In this study, we analyze the debonding of natural gas hydrate sediment (NGHS) particle...Weak cementation between natural gas hydrates and mud–sand seriously affects the solid-fluidized mining of natural gas hydrates. In this study, we analyze the debonding of natural gas hydrate sediment (NGHS) particles by applying the principle of spiral-cyclone coupling separation. To achieve this, weakly cemented NGHS particle and mechanical models were established. In the flow field of the spiral-cyclone flow-coupling separator, the motion characteristics of the weakly cemented NGHS particles and the destruction process of the cementation bond were analyzed. The destruction of the bonds mainly occurred in the spiral channel, and the destruction efficiency of the bonds was mainly affected by the rotational speed. Collision analysis of the particles and walls showed that when the velocity is 10–16 m·s^(−1), the cementation bond can be broken. The greater the speed, the better the effect of the bond fracture. The breaking rate of the cementation bonds was 85.7%. This study is significant for improving the degumming efficiency in natural gas hydrate exploitation, improving the recovery efficiency of hydrates, and promoting the commercialization of hydrate solid fluidization exploitation.展开更多
Utilizing mine solid waste as a partial cement substitute(CS)to develop new cementitious materials is a significant technological innovation that will decrease the expenses associated with filling mining.To realize th...Utilizing mine solid waste as a partial cement substitute(CS)to develop new cementitious materials is a significant technological innovation that will decrease the expenses associated with filling mining.To realize the resource utilization of magnesium slag(MS)and blast furnace slag(BFS),the effects of different contents of MS and BFS as partial CSs on the deformation and energy characteristics of cemented tailings backfill on different curing ages(3,7,and 28 d)were discussed.Meanwhile,the destabilization failure energy criterion of the backfill was established from the direction of energy change.The results show that the strength of all backfills increased with increasing curing age,and the strengths of the backfills exceeded 1.342 MPa on day 28.The backfill with 50%BFS+50%cement has the best performance in mechanical properties(the maximum strength can reach 6.129 MPa)and is the best choice among these CS combinations.The trend in peak strain and elastic modulus of the backfill with increasing curing age may vary depending on the CS combination.The energy index at peak stress of the backfill with BFS as a partial CS was significantly higher than that of the backfill under other CS combinations.In contrast,the enhancement of the energy index when MS was used as a partial CS was not as significant as BFS.Sharp changes in the energy consumption ratio after continuous smooth changes can be used as a criterion for destabilization and failure of the backfill.The research results can provide guidance for the application of MS and BFS as partial CSs in mine filling.展开更多
The strength of backfill body is a crucial parameter in backfilling mining,and the failure process of cemented backfill body is essentially an energy dissipation process.To investigate the effects of curing age and ce...The strength of backfill body is a crucial parameter in backfilling mining,and the failure process of cemented backfill body is essentially an energy dissipation process.To investigate the effects of curing age and cement-sand ratio on the strength and energy consumption of backfill,whole tailings were used as aggregate to prepare slurry with mass concentration of 74%,and the slurry with cement-sand ratio of 1:4,1:6,1:8 and 1:12 was poured into backfill.Uniaxial compression tests were conducted on backfill body specimens that had been cured for 7 days,14 days,28 days,and 45 days.It aims at studying the compressive strength,damage,energy storage limit,energy dissipation,and crack propagation of the fill.The results show that when the cement-sand ratio is held constant,the strength of the backfill increases with curing age.Simultaneously,when the curing age is fixed,the strength is positively correlated with the cement-sand ratio.During uniaxial compression tests,it is observed that the pre-peak energy consumption,post-peak energy consumption,total energy consumption,and unit volume strain energy of the cemented backfill body exhibit exponential relationships with both curing age and cement-sand ratio.The energy storage limit of the backfill reflects its capacity to absorb energy prior to failure,while the relationship between damage and energy consumption provides an accurate depiction of its internal failure mechanisms at different stages.In the failure process of the cemented backfill body,primary cracks accompany secondary cracks,many microcracks initiate and propagate from the stress direction,and crack propagation consumes a significant amount of energy.This study on the strength,energy storage limit,and failure of the cemented backfill body can provide valuable insights for mine safety production.展开更多
The first author proposed the concept of the cemented material dam （CMD） in 2009. This concept was aimed at building an environmentally friendly dam in a safer and more economical way for both the dam and the area d...The first author proposed the concept of the cemented material dam （CMD） in 2009. This concept was aimed at building an environmentally friendly dam in a safer and more economical way for both the dam and the area downstream. The concept covers the cemented sand, gravel, and rock dam （CSGRD）, the rockfill concrete （RFC） dam （or the cemented rockfill dam, CRD）, and the cemented soil dam （CSD）. This paper summarizes the concept and principles of the CMD based on studies and practices in projects around the world. It also introduces new developments in the CSGRD, CRD, and CSD.展开更多
Brittle fracture of cement sheath, induced by perforation and stimulation treatments, can cause cross flow of formation fluid and increase casing damage. A novel agent XL was developed for solving the problem. Experim...Brittle fracture of cement sheath, induced by perforation and stimulation treatments, can cause cross flow of formation fluid and increase casing damage. A novel agent XL was developed for solving the problem. Experimental results showed that the toughness of the set cement containing XL was improved remarkably. The engineering properties of the slurry containing XL, drag reducer USZ （0.2% BWOC）, filtrate loss additive F 17B （1.2% BWOC） and crystalloid expanding agent F17A （3% BWOC） could meet technical requirements of cementing operation. After perforation, good quality cement sheath enhanced with XL was observed by CBL/VDL logs in a deep well.展开更多
Ti(C,N)-Mo_(2)C-Ni cermet as alternative materials was explored for use in alkaline conditions,replacing the WC-Co cemented carbides,since Co is classified as a potentially carcinogenic substance and there is potentia...Ti(C,N)-Mo_(2)C-Ni cermet as alternative materials was explored for use in alkaline conditions,replacing the WC-Co cemented carbides,since Co is classified as a potentially carcinogenic substance and there is potential hazard of“hard metal disease”under the exposure to cobalt dust.The changes in microstructure,corrosion rate and volumetric loss rate of the two materials were compared under electrochemical corrosion and erosion-corrosion in alkaline environment.The results demonstrates that Ti(C,N)-Mo_(2)C-Ni cermet undergoes passivation when exposed to electrochemical corrosion of NaOH solution,resulting in a significant increase in oxygen content on the corroded surface.The corrosion rate of cermet is approximately one order of magnitude lower than that of the cemented carbide.Under the erosion-corrosion of an alkaline sand-water mixture,both the cermet and cemented carbide experience a gradual increase in volumetric loss rate with prolonging the erosion time.During erosion,the rim phase in cermet is fragile,so cracks easily penetrate it while the core phase remains intact.The medium-grained cemented carbide commonly demonstrates transgranular fracture mode,while in the fine-grained cemented carbide,cracks tend to propagate along phase boundaries.The erosive wear and damage caused by sand particles play a predominant role in the erosion-corrosion process of alkaline sand-water mixtures.This process represents an accelerated destructive phenomenon influenced and intensified by the combined effects of corrosion and erosion.It is confirmed that using cermet as an alternative anti-wear material to cemented carbides is feasible under alkaline conditions,and even better.展开更多
The electrochemical corrosion of ductile pipes(DPs)in drinking water distribution systems(DWDS)has a crucial impact on cement-mortar lining(CML)failure and metal release,potentially leading to drinking water quality d...The electrochemical corrosion of ductile pipes(DPs)in drinking water distribution systems(DWDS)has a crucial impact on cement-mortar lining(CML)failure and metal release,potentially leading to drinking water quality deterioration and posing a risk to public health.An in-situ scanning vibrating electrode technique(SVET)with micron-scale resolution,microscopic scale detection and water quality analysis were used to investigate the corrosion behavior and metal release from DPs throughout the whole CML failure process.Metal pollutants release occurred at three different stages of CML failure process,and there are potential risks of water quality deterioration exceeding the maximum allowable levels set by national standards in the partial failure stage and lining peeling stage.Furthermore,the effects of water chemistry(Cl^(−),SO_(4)^(2−),NO_(3)−,and Ca^(2+))on corrosion scale growth and iron release activity,were investigated during the CML partial failure stage.Results showed that the CML failure process in DPs was accelerated by the autocatalysis of localized corrosion.Cl^(−)was found to damage the uncorroded metal surface,while SO_(4)^(2−)mainly dissolved the corrosion scale surface,increasing iron release.Both the oxidation of NO_(3)−and selective sedimentation of Ca2+were found to enhance the stability of corrosion scales and inhibit iron release.展开更多
Using cemented rockfill to replace coal pillars offers an effective solution for reducing solid waste while ensuring the safety of gob-side entries.However,achieving the balance among low cost,high waste recycling rat...Using cemented rockfill to replace coal pillars offers an effective solution for reducing solid waste while ensuring the safety of gob-side entries.However,achieving the balance among low cost,high waste recycling rates,and adequate strength remains a significant challenge for cemented rockfill.This study used a composite alkali activator to activate gangue cemented rockfill.The compressive strength,scanning electron microscopy,energy dispersive spectrometer,mercury intrusion porosimetry,X-ray diffraction,and thermogra-vimetric tests were carried out to investigate the effect of the composite alkali activator proportion on the compressive strength,micro-structure,and composition of the cemented rockfill.The calcium silicate hydrate(C–S–H)molecular model of cemented rockfill was con-structed to explore the fracture evolution of the nucleated molecular structure under tension.The results show that compressive strength initially increased and then decreased with the activator proportion,the optimal activator proportion of 1:2 resulted in a 31.25%increase in strength at 3 d.This reasonable activator proportion strengthens the pozzolanic effect of gangue,and consumes more calcium hydroxide to inhibit its agglomeration,ultimately achieving the densification of microstructure.The activator proportion inevitably substitutes calcium ions with sodium ions in the C–S–H molecular model.The 12%substitution of calcium ions increases the adhesion between silicon chain layers,which is beneficial to the interlayer stress transfer.This work proposes a method for preparing low-cost cemented rockfill from al-kali-activated gangue,which can be used for solid waste recycling and reducing cement consumption to achieve low-carbon goals.展开更多
To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,t...To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,thereby improving both microstructure uniformity and mechanical properties of sintered bodies.The results indicate that WIP reduces defects in MEX greens,thus decreasing the dimensions and numbers of defects,modifying shapes of pores within sintered bodies,while preserving surface quality and shape characteristics.Compared with WC-9Co prepared via MEX followed by debinding and sintering(DS),the hardness of WC-9Co prepared using MEX-WIP-DS does not change significantly,ranging HV_(30)1494-1508,the transverse rupture strength increases by up to 49.3%,reaching 2998-3514 MPa,and the fracture toughness remains high,ranging 14.8-17.0 MPa·m^(1/2).The mechanical properties surpass comparable cemented carbides fabricated through other AM methods and are comparable to those produced by powder metallurgy.The integration of green WIP into MEX-DS broadens the MEX processing window,and improves the overall mechanical properties of MEX AM WC-Co cemented carbides.展开更多
After the ultralow emission transformation of coal-fired power plants,cement production became China’s leading industrial emission source of nitrogen oxides.Flue gas dust contents at the outlet of cement kiln preheat...After the ultralow emission transformation of coal-fired power plants,cement production became China’s leading industrial emission source of nitrogen oxides.Flue gas dust contents at the outlet of cement kiln preheaters were as high as 80-100 g/m^(3),and the calcium oxide content in the dust exceeded 60%.Commercial V_(2)O_(5)(-WO_(3))/TiO_(2) catalysts suitable for coal-fired flue gas suffer from alkaline earth metal Ca poisoning of cement kiln flue gas.Recent studies have also identified the poisoning of cement kiln selective catalytic reaction(SCR)catalysts by the heavy metals lead and thallium.Investigation of the poisoning process is the primary basis for analyzing the catalytic lifetime.This review summarizes and analyzes the SCR catalytic mechanism and chronicles the research progress concerning this poisoning mechanism.Based on the catalytic and toxification mechanisms,it can be inferred that improving the anti-poisoning performance of a catalyst enhances its acidity,surface redox performance-active catalytic sites,and shell layer protection.The data provide support in guiding engineering practice and reducing operating costs of SCR plants.Finally,future research directions for SCR denitrification catalysts in the cement industry are discussed.This study provides critical support for the development and optimization of poisoning-resistant SCR denitrification catalysts.展开更多
The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the a...The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the amount of acid-impregnated slag dosed on the compressive strength and water resistance of LR-MOC.The results showed that the magnesium element in the boron mud could be maximally leached under the conditions of 1:1 concentration of hydrochloric acid at room temperature,liquid-solid ratio of 2.5 mL·g^(-1),and reaction time of 5 h,and the main products were amorphous SiO_(2) as well as a small amount of magnesium olivine which had not been completely reacted.The LR-MOC prepared using the acid-soaked mixture could reach a softening coefficient of 0.85 for 28 d of water immersion when the molar ratio of MgO/MgCl_(2) was 2.2,the amount of water added was 0 g,and the acid-soaked slag dosing was 40 wt%,which also led to an appreciable late-strength,with an increase of 19.4%in compressive strength at 28 d compared to that at 7 d.Unlike previous studies,LR-MOC prepared in this way has a final strength phase that is not the more easily hydrolysed 3-phase but the lath-like 5-phase.For this phenomenon,we analyzed the mechanism and found that,during the acid leaching process,a part of amorphous SiO_(2) dissolved in the acid leaching solution formed a silica sol,in which Mg^(2+)played a bridging role to make the silica sol more stable.With the addition and hydrolysis of MgO,the silica sol gel coagulation slows down,providing a capping layer to inhibit the hydrolysis of the 5-phase crystals and providing some strength after coagulation.The amorphous SiO_(2) in the other part of the acid-impregnated slag generated M-S-H gel with Mg^(2+)and OH-,which synergised with the dense structure composed of interlocking crystals to improve the water resistance of LR-MOC.展开更多
Paste and mortar specimens were prepared with sulfoaluminate cement(SAC),P⋅O 42.5 ordinary Portland cement(OPC),and standard sand,and mixed and cured with pure water and artificial seawater,respectively.The mechanical...Paste and mortar specimens were prepared with sulfoaluminate cement(SAC),P⋅O 42.5 ordinary Portland cement(OPC),and standard sand,and mixed and cured with pure water and artificial seawater,respectively.The mechanical properties of mortar specimens were tested.Hydration and microstructure of paste specimens were also investigated using X-ray diffraction(XRD),scanning electron microscope(SEM),and 27Al nuclear magnetic resonance(NMR),respectively.The results indicate that SAC mortar samples mixed and cured by seawater have faster strength growth before 28 d and higher compressive strength than OPC mortar samples.Compared to curing in deionized water,the hydration products of SAC are somewhat coarser when cured in simulated seawater.The evolution of aluminum phase hydration products during the hydration process of SAC mixed and cured in simulated seawater is quite different from that of OPC.From 3 to 28 d,the content of each aluminum phase hydration product in SAC paste cured in simulated seawater changed little,while that in OPC paste changed significantly;for example,from 7 to 28 d,the content of ettringite(AFt)in OPC paste increased significantly.This type of AFt formed loosely,harming the mortar's microstructure.展开更多
The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compressio...The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of aggregates.The mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically analyzed.The results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,respectively.However,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the aggregates.Theσ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite trend.Theε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse aggregates.With increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure.展开更多
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financial support of National Natural Science Foundation of China(72174196 and 71874193)the Open Fund of State Key Laboratory of Coal Resources and Safe Mining(SKLCRSM21KFA05)National Program for Support of Top-Notch Young Professionals.
文摘The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change,a key component of which is carbon capture,utilization,and storage(CCUS)technology.Despite its importance,there is a lack of empirical assessments of early opportunities for CCUS implementation in the cement sector.In this study,a comprehensive onshore and offshore source–sink matching optimization assessment framework for CCUS retrofitting in the cement industry,called the SSM-Cement framework,is proposed.The framework comprises four main modules:the cement plant suitability screening module,the storage site assessment module,the source–sink matching optimization model module,and the economic assessment module.By applying this framework to China,919 candidates are initially screened from 1132 existing cement plants.Further,603 CCUS-ready cement plants are identified,and are found to achieve a cumulative emission reduction of 18.5 Gt CO_(2) from 2030 to 2060 by meeting the CCUS feasibility conditions for constructing both onshore and offshore CO_(2) transportation routes.The levelized cost of cement(LCOC)is found to range from 30 to 96(mean 73)USD·(t cement)^(-1),while the levelized carbon avoidance cost(LCAC)ranges from^(-5) to 140(mean 88)USD·(t CO_(2))^(-1).The northeastern and northwestern regions of China are considered priority areas for CCUS implementation,with the LCAC concentrated in the range of 35 to 70 USD·(t CO_(2))^(-1).In addition to onshore storage of 15.8 Gt CO_(2) from 2030 to 2060,offshore storage would contribute 2.7 Gt of decarbonization for coastal cement plants,with comparable LCACs around 90 USD·(t CO_(2))^(-1).
基金financially supported by the National Key Research and Development Program of China(No.2021YFB3701800)Special funding support for the Yuelu Mountain National University Science and Technology City“Ranking the Top of the List”Research Project:(Tunnel Boring Machine High-performance Long-life Cutting Tools)the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘The good combination of mechanical and wear properties for cemented carbides is crucial.In this work,the wear behavior of functionally graded cemented carbide(FGCC)and non-graded cemented carbide(CC),with CoNiFeCr multi-principal-element alloy(MPEA)binder,has been investigated by performing sliding wear tests and composition characterization.The results showed that compared with CC,FGCC had higher hardness,stronger fracture toughness,better wear performance,and similar TRS.FGCCs exhibited lower wear rates(3.44×10^(−7)–6.95×10^(−6)mm^(3)/(N m))and coefficients of friction(COFs)(0.27–0.39)than CCs from RT to 600℃due to mitigation of multiple risks caused by binder removal,fragmentation and pull-out of WC grains,high-temperature oxidation and softening.In the low-temperature wear stage,the MPEA binder underwent dynamic recrystallization(DRX)and twinning deformation before removing from the surface.The binder removal caused dislocation pile-ups and stacking faults(SFs)to form under high stress,resulting in fragmentation and pull-out of WC grains.The low-temperature wear was dominated by abrasive wear and adhesive wear,with a low wear rate and a high and unstable COF.In the high-temperature wear stage,initial pitting oxidation of WC grains generated many subgrain boundaries,reducing heat transfer and exacerbating oxidation,resulting in an oxide layer enriched with WO3,Mx Oy,and MWO4.High-temperature wear was dominated by oxidation wear and high-temperature softening,with a high wear rate and a low and smooth COF.The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr,but also a new approach for the preparation of cemented carbides with high wear resistance.
基金National Natural Science Foundation of China(No.41967035)。
文摘Treatment of peat soil foundation in Yunnan surrounding Dianchi and Erhai Lakes poses complex problems for engineering projects.It is insufficient to rely on ordinary cement to reinforce peat soil.In order to make the reinforcement reliable,this experiment mixed(ultrafine cement)UFC into ordinary cement to form a composite solidify agent.This study aimed to analyze the influence of UFC proportion on the strength of cement-soil in the peat soil environment.Unconfined compressive strength(UCS)and scanning electron microscope(SEM)tests were conducted on samples soaked for 28 and 90 days,respectively.The test results show that without considering the effects of Humic Acid(HA)and Fulvic Acid(FA),incorporating UFC can significantly improve the UCS of cement-soil.The rapid hydration of the fine particles generates a large number of cementitious products,improves the cohesion of the soil skeleton,and fills the pores.However,when the proportion of UFC increases,the aggregate structure formed by a larger quantity of fine particles reduces the hydration rate and degree of cement hydration,making the UCS growth rate of cement-soil insignificant.In the peat soil environment,HA significantly weakened the UCS of cement-soil in both physical and chemical aspects.However,UFC can mitigate the adverse effect of HA on cement-soil by its small particle size,high surface energy,and solid binding ability.In addition,FA has a positive effect on the UCS of cement-soil soaked for 28 days and 90 days.The UFC addition could promote the enhancement effect of FA on cement-soil UCS.SEM test results showed that cement hydration products increased significantly with the increase of UFC proportion,and cementation between hydration products and soil particles was enhanced.The size and connectivity of cement-soil pores were significantly reduced,thereby improving cement-soil structural integrity.
基金funded by the State Key Laboratory of Natural Gas Hydrate of China(2022-KFJJ-SHW)the National Key Research and Development Program of China(2021YFC2800903)+2 种基金the National Natural Science Foundation of China(52004235)the National Natural Science Foundation General Program of China(52374011)the Miaozi Engineering Cultivation Project of Sichuan Science and Technology Department of China(MZG20230127).
文摘Weak cementation between natural gas hydrates and mud–sand seriously affects the solid-fluidized mining of natural gas hydrates. In this study, we analyze the debonding of natural gas hydrate sediment (NGHS) particles by applying the principle of spiral-cyclone coupling separation. To achieve this, weakly cemented NGHS particle and mechanical models were established. In the flow field of the spiral-cyclone flow-coupling separator, the motion characteristics of the weakly cemented NGHS particles and the destruction process of the cementation bond were analyzed. The destruction of the bonds mainly occurred in the spiral channel, and the destruction efficiency of the bonds was mainly affected by the rotational speed. Collision analysis of the particles and walls showed that when the velocity is 10–16 m·s^(−1), the cementation bond can be broken. The greater the speed, the better the effect of the bond fracture. The breaking rate of the cementation bonds was 85.7%. This study is significant for improving the degumming efficiency in natural gas hydrate exploitation, improving the recovery efficiency of hydrates, and promoting the commercialization of hydrate solid fluidization exploitation.
基金Projects(52274108,U2341265)supported by the National Natural Science Foundation of ChinaProject(2022YFC2904103)supported by the National Key Research and Development Program of China。
文摘Utilizing mine solid waste as a partial cement substitute(CS)to develop new cementitious materials is a significant technological innovation that will decrease the expenses associated with filling mining.To realize the resource utilization of magnesium slag(MS)and blast furnace slag(BFS),the effects of different contents of MS and BFS as partial CSs on the deformation and energy characteristics of cemented tailings backfill on different curing ages(3,7,and 28 d)were discussed.Meanwhile,the destabilization failure energy criterion of the backfill was established from the direction of energy change.The results show that the strength of all backfills increased with increasing curing age,and the strengths of the backfills exceeded 1.342 MPa on day 28.The backfill with 50%BFS+50%cement has the best performance in mechanical properties(the maximum strength can reach 6.129 MPa)and is the best choice among these CS combinations.The trend in peak strain and elastic modulus of the backfill with increasing curing age may vary depending on the CS combination.The energy index at peak stress of the backfill with BFS as a partial CS was significantly higher than that of the backfill under other CS combinations.In contrast,the enhancement of the energy index when MS was used as a partial CS was not as significant as BFS.Sharp changes in the energy consumption ratio after continuous smooth changes can be used as a criterion for destabilization and failure of the backfill.The research results can provide guidance for the application of MS and BFS as partial CSs in mine filling.
基金funded by the National Natural Science Foundation of China(52474131)the National Natural Science Foundation of China(42467022)+1 种基金the Yunnan Major Scientific and Technological Projects(Grant No.202202AG050014)the Yunnan Fundamental Research Projects(NO.202101BE070001-038,202201AT070146).
文摘The strength of backfill body is a crucial parameter in backfilling mining,and the failure process of cemented backfill body is essentially an energy dissipation process.To investigate the effects of curing age and cement-sand ratio on the strength and energy consumption of backfill,whole tailings were used as aggregate to prepare slurry with mass concentration of 74%,and the slurry with cement-sand ratio of 1:4,1:6,1:8 and 1:12 was poured into backfill.Uniaxial compression tests were conducted on backfill body specimens that had been cured for 7 days,14 days,28 days,and 45 days.It aims at studying the compressive strength,damage,energy storage limit,energy dissipation,and crack propagation of the fill.The results show that when the cement-sand ratio is held constant,the strength of the backfill increases with curing age.Simultaneously,when the curing age is fixed,the strength is positively correlated with the cement-sand ratio.During uniaxial compression tests,it is observed that the pre-peak energy consumption,post-peak energy consumption,total energy consumption,and unit volume strain energy of the cemented backfill body exhibit exponential relationships with both curing age and cement-sand ratio.The energy storage limit of the backfill reflects its capacity to absorb energy prior to failure,while the relationship between damage and energy consumption provides an accurate depiction of its internal failure mechanisms at different stages.In the failure process of the cemented backfill body,primary cracks accompany secondary cracks,many microcracks initiate and propagate from the stress direction,and crack propagation consumes a significant amount of energy.This study on the strength,energy storage limit,and failure of the cemented backfill body can provide valuable insights for mine safety production.
文摘The first author proposed the concept of the cemented material dam （CMD） in 2009. This concept was aimed at building an environmentally friendly dam in a safer and more economical way for both the dam and the area downstream. The concept covers the cemented sand, gravel, and rock dam （CSGRD）, the rockfill concrete （RFC） dam （or the cemented rockfill dam, CRD）, and the cemented soil dam （CSD）. This paper summarizes the concept and principles of the CMD based on studies and practices in projects around the world. It also introduces new developments in the CSGRD, CRD, and CSD.
文摘Brittle fracture of cement sheath, induced by perforation and stimulation treatments, can cause cross flow of formation fluid and increase casing damage. A novel agent XL was developed for solving the problem. Experimental results showed that the toughness of the set cement containing XL was improved remarkably. The engineering properties of the slurry containing XL, drag reducer USZ （0.2% BWOC）, filtrate loss additive F 17B （1.2% BWOC） and crystalloid expanding agent F17A （3% BWOC） could meet technical requirements of cementing operation. After perforation, good quality cement sheath enhanced with XL was observed by CBL/VDL logs in a deep well.
基金Chongqing Light Alloy Materials and Processing Engineering Technology Research Center Open Fund Project(GCZX201903)Yunnan Province Major Science and Technology Special Project Plan(202302AA310038)Sichuan University-Suining Municipal-University Cooperation Project(2023CDSN-12)。
文摘Ti(C,N)-Mo_(2)C-Ni cermet as alternative materials was explored for use in alkaline conditions,replacing the WC-Co cemented carbides,since Co is classified as a potentially carcinogenic substance and there is potential hazard of“hard metal disease”under the exposure to cobalt dust.The changes in microstructure,corrosion rate and volumetric loss rate of the two materials were compared under electrochemical corrosion and erosion-corrosion in alkaline environment.The results demonstrates that Ti(C,N)-Mo_(2)C-Ni cermet undergoes passivation when exposed to electrochemical corrosion of NaOH solution,resulting in a significant increase in oxygen content on the corroded surface.The corrosion rate of cermet is approximately one order of magnitude lower than that of the cemented carbide.Under the erosion-corrosion of an alkaline sand-water mixture,both the cermet and cemented carbide experience a gradual increase in volumetric loss rate with prolonging the erosion time.During erosion,the rim phase in cermet is fragile,so cracks easily penetrate it while the core phase remains intact.The medium-grained cemented carbide commonly demonstrates transgranular fracture mode,while in the fine-grained cemented carbide,cracks tend to propagate along phase boundaries.The erosive wear and damage caused by sand particles play a predominant role in the erosion-corrosion process of alkaline sand-water mixtures.This process represents an accelerated destructive phenomenon influenced and intensified by the combined effects of corrosion and erosion.It is confirmed that using cermet as an alternative anti-wear material to cemented carbides is feasible under alkaline conditions,and even better.
基金supported by the National Natural Science Foundation of China(Nos.51808158,52170101,and 52200116)Tianjin Natural Science Foundation(No.23JCYBJC00640).
文摘The electrochemical corrosion of ductile pipes(DPs)in drinking water distribution systems(DWDS)has a crucial impact on cement-mortar lining(CML)failure and metal release,potentially leading to drinking water quality deterioration and posing a risk to public health.An in-situ scanning vibrating electrode technique(SVET)with micron-scale resolution,microscopic scale detection and water quality analysis were used to investigate the corrosion behavior and metal release from DPs throughout the whole CML failure process.Metal pollutants release occurred at three different stages of CML failure process,and there are potential risks of water quality deterioration exceeding the maximum allowable levels set by national standards in the partial failure stage and lining peeling stage.Furthermore,the effects of water chemistry(Cl^(−),SO_(4)^(2−),NO_(3)−,and Ca^(2+))on corrosion scale growth and iron release activity,were investigated during the CML partial failure stage.Results showed that the CML failure process in DPs was accelerated by the autocatalysis of localized corrosion.Cl^(−)was found to damage the uncorroded metal surface,while SO_(4)^(2−)mainly dissolved the corrosion scale surface,increasing iron release.Both the oxidation of NO_(3)−and selective sedimentation of Ca2+were found to enhance the stability of corrosion scales and inhibit iron release.
基金supported by the Key Research and Development Special Tasks of Xinjiang,China (No.2022B01051-2)the National Natural Science Foundation of China (Nos.U23B2091,42372328,and 52478253)+1 种基金the Natural Science Foundation of Jiangsu Province,China (No.BK20240209)the Science and Technology Program Special Fund of Jiangsu Province (Frontier Leading Technology Basic Research) Major projects,China (No.BK 20222004)
文摘Using cemented rockfill to replace coal pillars offers an effective solution for reducing solid waste while ensuring the safety of gob-side entries.However,achieving the balance among low cost,high waste recycling rates,and adequate strength remains a significant challenge for cemented rockfill.This study used a composite alkali activator to activate gangue cemented rockfill.The compressive strength,scanning electron microscopy,energy dispersive spectrometer,mercury intrusion porosimetry,X-ray diffraction,and thermogra-vimetric tests were carried out to investigate the effect of the composite alkali activator proportion on the compressive strength,micro-structure,and composition of the cemented rockfill.The calcium silicate hydrate(C–S–H)molecular model of cemented rockfill was con-structed to explore the fracture evolution of the nucleated molecular structure under tension.The results show that compressive strength initially increased and then decreased with the activator proportion,the optimal activator proportion of 1:2 resulted in a 31.25%increase in strength at 3 d.This reasonable activator proportion strengthens the pozzolanic effect of gangue,and consumes more calcium hydroxide to inhibit its agglomeration,ultimately achieving the densification of microstructure.The activator proportion inevitably substitutes calcium ions with sodium ions in the C–S–H molecular model.The 12%substitution of calcium ions increases the adhesion between silicon chain layers,which is beneficial to the interlayer stress transfer.This work proposes a method for preparing low-cost cemented rockfill from al-kali-activated gangue,which can be used for solid waste recycling and reducing cement consumption to achieve low-carbon goals.
基金supported by the Key Project of Chinese Academy of Engineering(No.2019-XZ-11)the General Project of Chinese Academy of Engineering(No.2023-XY-18)+1 种基金the Open Fund of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials of China(No.HKDNM201907)the Independent Project of State Key Laboratory of Powder Metallurgy,China。
文摘To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,thereby improving both microstructure uniformity and mechanical properties of sintered bodies.The results indicate that WIP reduces defects in MEX greens,thus decreasing the dimensions and numbers of defects,modifying shapes of pores within sintered bodies,while preserving surface quality and shape characteristics.Compared with WC-9Co prepared via MEX followed by debinding and sintering(DS),the hardness of WC-9Co prepared using MEX-WIP-DS does not change significantly,ranging HV_(30)1494-1508,the transverse rupture strength increases by up to 49.3%,reaching 2998-3514 MPa,and the fracture toughness remains high,ranging 14.8-17.0 MPa·m^(1/2).The mechanical properties surpass comparable cemented carbides fabricated through other AM methods and are comparable to those produced by powder metallurgy.The integration of green WIP into MEX-DS broadens the MEX processing window,and improves the overall mechanical properties of MEX AM WC-Co cemented carbides.
基金supported by the Basic Research Business Fund Grant Program for University of Science and Technology Beijing (No.0650)the Fundamental Research Funds for the Central Universities (No.FRF-TP-22-091A1)the Interdisciplinary Research Project for Young Teachers of USTB (Fundamental Research Funds for the Central Universities) (No.FRF-IDRY-22-010).
文摘After the ultralow emission transformation of coal-fired power plants,cement production became China’s leading industrial emission source of nitrogen oxides.Flue gas dust contents at the outlet of cement kiln preheaters were as high as 80-100 g/m^(3),and the calcium oxide content in the dust exceeded 60%.Commercial V_(2)O_(5)(-WO_(3))/TiO_(2) catalysts suitable for coal-fired flue gas suffer from alkaline earth metal Ca poisoning of cement kiln flue gas.Recent studies have also identified the poisoning of cement kiln selective catalytic reaction(SCR)catalysts by the heavy metals lead and thallium.Investigation of the poisoning process is the primary basis for analyzing the catalytic lifetime.This review summarizes and analyzes the SCR catalytic mechanism and chronicles the research progress concerning this poisoning mechanism.Based on the catalytic and toxification mechanisms,it can be inferred that improving the anti-poisoning performance of a catalyst enhances its acidity,surface redox performance-active catalytic sites,and shell layer protection.The data provide support in guiding engineering practice and reducing operating costs of SCR plants.Finally,future research directions for SCR denitrification catalysts in the cement industry are discussed.This study provides critical support for the development and optimization of poisoning-resistant SCR denitrification catalysts.
基金Funded by Provincial Basic Research Projects(No.LJKMZ20220947)。
文摘The effects of liquid-solid ratio and reaction time on the leaching rate of magnesium at room temperature were investigated,as well as the effects of the molar ratio of MgO/MgCl_(2),the amount of water added,and the amount of acid-impregnated slag dosed on the compressive strength and water resistance of LR-MOC.The results showed that the magnesium element in the boron mud could be maximally leached under the conditions of 1:1 concentration of hydrochloric acid at room temperature,liquid-solid ratio of 2.5 mL·g^(-1),and reaction time of 5 h,and the main products were amorphous SiO_(2) as well as a small amount of magnesium olivine which had not been completely reacted.The LR-MOC prepared using the acid-soaked mixture could reach a softening coefficient of 0.85 for 28 d of water immersion when the molar ratio of MgO/MgCl_(2) was 2.2,the amount of water added was 0 g,and the acid-soaked slag dosing was 40 wt%,which also led to an appreciable late-strength,with an increase of 19.4%in compressive strength at 28 d compared to that at 7 d.Unlike previous studies,LR-MOC prepared in this way has a final strength phase that is not the more easily hydrolysed 3-phase but the lath-like 5-phase.For this phenomenon,we analyzed the mechanism and found that,during the acid leaching process,a part of amorphous SiO_(2) dissolved in the acid leaching solution formed a silica sol,in which Mg^(2+)played a bridging role to make the silica sol more stable.With the addition and hydrolysis of MgO,the silica sol gel coagulation slows down,providing a capping layer to inhibit the hydrolysis of the 5-phase crystals and providing some strength after coagulation.The amorphous SiO_(2) in the other part of the acid-impregnated slag generated M-S-H gel with Mg^(2+)and OH-,which synergised with the dense structure composed of interlocking crystals to improve the water resistance of LR-MOC.
基金Funded by Science and Technology Development Project of China Railway Design Corporation(Nos.2023A0226407,2023B03040003)。
文摘Paste and mortar specimens were prepared with sulfoaluminate cement(SAC),P⋅O 42.5 ordinary Portland cement(OPC),and standard sand,and mixed and cured with pure water and artificial seawater,respectively.The mechanical properties of mortar specimens were tested.Hydration and microstructure of paste specimens were also investigated using X-ray diffraction(XRD),scanning electron microscope(SEM),and 27Al nuclear magnetic resonance(NMR),respectively.The results indicate that SAC mortar samples mixed and cured by seawater have faster strength growth before 28 d and higher compressive strength than OPC mortar samples.Compared to curing in deionized water,the hydration products of SAC are somewhat coarser when cured in simulated seawater.The evolution of aluminum phase hydration products during the hydration process of SAC mixed and cured in simulated seawater is quite different from that of OPC.From 3 to 28 d,the content of each aluminum phase hydration product in SAC paste cured in simulated seawater changed little,while that in OPC paste changed significantly;for example,from 7 to 28 d,the content of ettringite(AFt)in OPC paste increased significantly.This type of AFt formed loosely,harming the mortar's microstructure.
基金financially supported by the National Natural Science Foundation of China(Nos.52174092,51904290,and 52374147)the Natural Science Foundation of Jiangsu Province,China(No.BK20220157)+2 种基金the Fundamental Research Funds for the Central Universities,China(No.2022YCPY0202)the National Key Research and Development Program of China(No.2023YFC3804204)the Major Program of Xinjiang Uygur Autonomous Region S cience and Technology(No.2023A01002)。
文摘The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious materials.Consequently,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of aggregates.The mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically analyzed.The results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,respectively.However,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the aggregates.Theσ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite trend.Theε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse aggregates.With increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure.
