Table of Content

Volume 44 Issue 10
15 October 2025

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Cement and Concrete

Early Age Properties of Rapid Hardening and Early Strength Cementitious Material at Negative Temperature Environment: a Review

ZHANG Chao, WANG Zhihang, WANG Chao, NIE Liangxue, LI Bingchen, LUO Xin, CHEN Tao

2025, 44(10):  3503-3516.  doi:10.16552/j.cnki.issn1001-1625.2025.0357

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The urgent repair and construction engineering requires that the cementitious material must have the characteristics of rapid hardening and early strength, and the cementitious material must face negative temperature environment in high altitude-high latitude areas and cold weather in winter. Traditional cementitious material cannot hydrate normally in this environment, and do not solidify and without strength. Magnesium phosphate cement, sulphoaluminate cement, alkali-activated slag cementitious material and composite cementitious material have the characteristics of fast setting and rapid hardening, hydration heat release concentration, early strength and high strength, showing the potential of application in negative temperature environment. In this paper, the research progress on the early age properties of rapid hardening and early strength cementitious materials under negative temperature environment was reviewed. The effects of the types and properties of raw materials and the ratio of raw materials on the early strength formation of magnesium phosphate cement under negative temperature environment were emphatically analyzed, as well as the improvement effects of cementing material components, antifreeze, early strength agents and nanomaterials on the early age property of sulphoaluminate cement. In addition, the future development of rapid hardening and early strength cementitious material under negative temperature environment was prospected.

Influences of C-S-H/PCE Seed Crystals on Microstructure of Early Hydration Products of C₃S under Different Curing Conditions

WANG Yanrong, WU Yonghua, YI Ang, WANG Xin, CHEN Shuwen

2025, 44(10):  3517-3524.  doi:10.16552/j.cnki.issn1001-1625.2025.0465

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Tricalcium silicate (C₃S) is the main mineral phase of ordinary Portland cement (OPC), and its hydration products determine the properties of OPC-based materials. The addition of hydrated calcium silicate (C-S-H) seed crystals can regulate the microstructure of hydration products of C₃S. In this paper, polycarboxylate acid (PCE) was used as the dispersant, and the hydrated calcium silicate/PCE (C-S-H/PCE) seed crystals with different Ca/Si molar ratios were synthesized by co-precipitation method. The influence mechanism of C-S-H/PCE seed crystals on the microstructure of the early hydration products of C₃S single minerals was investigated by using XRD, thermogravimetric analysis and SEM characterization. The results show that when standard cured at 20 ℃ for 24 h, the incorporation of C-S-H/PCE seed crystals can promote the hydration of C₃S and more calcium hydroxide (CH) is formed. When the Ca/Si molar ratio of seed crystals is 1.2, the highest amount of C-S-H gel is induced and the structure is the most compact. When steam cured at 70 ℃ for 24 h, the addition of C-S-H/PCE seed crystals might further increase the quantity of C₃S hydration products and enhance the microstructure density. The study reveals the regulation mechanism of Ca/Si molar ratio and temperature synergistic effect on the quantity and morphology of C₃S hydration products, providing a reference for the rational application of C-S-H/PCE seed crystals.

Application of Modern Testing and Analysis Technologies in Thermal Calibration of Sintering Systems: a Brief Analysis

XIONG Yagang, ZHAO Qinglin, KE Zhuang, YU Tian, SONG Yuzhang, MA Wenjie, YAO Xiaojie, CHEN Xuejun

2025, 44(10):  3525-3535.  doi:10.16552/j.cnki.issn1001-1625.2025.0431

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To address the limitations of traditional thermal measurement methods in detailed condition analysis, this paper integrated typical production cases to systematically explore the application of modern testing techniques—such as differential thermal analysis (DTA), petrographic analysis, and laser particle size analysis—as well as computational fluid dynamics (CFD) numerical simulation, in deeply expanding the analysis of the operating conditions of cement kiln sintering systems. The results indicate that DTA can determine the combustion characteristics of coal, the presence of coal blending, and its effectiveness based on characteristic mass loss and exothermic peaks during combustion. Petrographic analysis, through examination of major mineral phase content and structural defects, reveals the adverse impacts of sintering and cooling regimes, as well as raw material quality, on clinker quality. Laser particle size analysis provides more accurate and comprehensive particle size parameters, clarify the influence of raw meal particle size on the system's dust collection efficiency (for example, it can reveal that raw meal with an excessively low median diameter D₅₀ will cause a sharp increase in dust concentration of C1 preheater).The accuracy of CFD numerical simulation results is highly dependent on the setting of boundary conditions. Using correct test data as boundary conditions can realistically reflect the system's operational status, thereby clarifying the potential impacts of issues such as poor air supply and vortex energy dissipation on clinker cooling efficiency and thermal energy utilization rate. Through in-depth analysis of the variation patterns of relevant parameters, this paper proposes solutions to optimize the process, thermal regime, and improve the system's structural design, emphasizing the important value of advanced testing and analysis technologies in enhancing system thermal efficiency and operational stability.

Stability of Mortar Based on Flow Slump Law on an Inclined Plane

WU Hao, XU Gelong, SONG Qiulei, ZHOU Jiehang, CAI Jiwei, YE Guolin, CHEN Jinge, ZHANG Qiubin

2025, 44(10):  3536-3546.  doi:10.16552/j.cnki.issn1001-1625.2025.0492

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The high stability of fresh mortar is an important guarantee for the homogeneity of hardened mortar. In this study, the inclined plane method was used to evaluate the stability of fresh mortar, and compared with the mortar stratification method and bleeding rate provided by "Ready-mixed mortar" (GB/T 25181—2019), the corresponding relationship between the stability of fresh mortar and the flow slump on an inclined plane was established. Based on the "film thickness theory", the formation mechanism of mortar segregation was investigated from the microscopic view. The results show that the ratio of mortar flow angle A_m and paste flow angle A_p (A_m/A_p) obtained by inclined plane test is an effective index for evaluating the dynamic segregation of fresh mortar, and the fresh mortar with lower A_m/A_p has larger stratification degree and higher bleeding rate with poor stability. The A_m/A_p of mortar in good condition is 1.17~1.27, and the A_m/A_p of 1.17 is the boundary between stable state and unstable state of mortar. Appropriate determination the paste saturation (the ratio of the thickness of the paste layer stably wrapped on the fine aggregate and the total paste layer thickness), is crucial for balance the bond performance of fresh paste while ensuring its stability.

Effects of Hybrid Glass Fiber and Steel Fiber on Dynamic Splitting Tensile Properties of Seawater Coral Sand Engineered Cementitious Composites

QIN Yulin, MU Chaomin, ZHANG Xiaoyu, ZHONG Meiting, ZHANG Yu

2025, 44(10):  3547-3561.  doi:10.16552/j.cnki.issn1001-1625.2025.0493

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The use of seawater coral sand to prepare engineered cementitious composites in island reef engineering construction has the advantages of controlling engineering cost and shortening engineering construction period. In order to study the effect of volume fraction of glass fiber (GF) and steel fiber (SF) on the dynamic splitting tensile properties of seawater coral sand engineered cementitious composites (SCECC), the dynamic and static splitting tensile properties of SCECC with different volume fractions of GF instead of SF were tested. The effects of volume ratio of GF and SF and stress rate on energy dissipation characteristics, dynamic intensity growth factor (DIF), dynamic splitting tensile strength and tensile strain field of SCECC were discussed. The results show that the addition of SF and GF reduces the static splitting tensile strength of SCECC with the increase of volume fraction of GF. When the volume fraction of GF is 0% and the volume fraction of SF is 1.500%, the static splitting tensile strength increases by 33.56%. When the volume ratio of GF to SF is 1:3 and the stress rate is 377.08 GPa/s, the dynamic splitting tensile strength reaches the maximum value of 22.33 MPa. With the increase of stress rate, the sensitivity of DIF of SCECC to stress rate increases, and the maximum DIF is 2.58. Under the stress rate grade Ⅳ (371.29~381.46 GPa/s), the dissipation rate of SCECC increased by 34.54%. The hybrid incorporation of SF and GF improves the fracture mode and transforms the crack from single crack to multiple cracks. The analysis of digital image correlation technique shows that the incorporation of SF and GF can alleviate the strain concentration and enhance the damage resistance of SCECC.

Mechanical and Microstructural Characteristics of Basalt Fiber Bar Reinforced Ultra-High Performance Cementitious Composite Repair Materials for Aged Cable Tunnels

XUE Qiang, ZHENG Tianyu, CAI Xiaoyu, LIU Shouquan, ZHAN Jinke, CUI Sheng'ai

2025, 44(10):  3562-3572.  doi:10.16552/j.cnki.issn1001-1625.2025.0401

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The underground environment where cable tunnels are located is complex, leading to severe performance degradation of the tunnel's concrete support structure due to corrosion. However, the insufficient performance of traditional repair materials often results in repeated cracking and water leakage in cable tunnels, and this degradation phenomenon is particularly pronounced in aged cable tunnels. Additionally, traditional copper-plated micro-fine steel fibers exhibit poor high-temperature resistance and corrosion resistance, making them unsuitable for complex underground environments. Therefore, this study adopted basalt fiber bar (BFB) to replace copper-plated micro-fine steel fibers and designed a basalt fiber bar reinforced ultra-high performance cementitious composite (BFB-UHPCC) repair material. The material's performance was investigated through mechanical tests and CT technology. The results show that the incorporation of BFB significantly enhances the material's mechanical properties, with compressive strength reaching 123.7 MPa and flexural strength reaching 20.0 MPa under steam curing. The combination of 1.5% (volume fraction) BFB and curing agent treatment yields the best toughness. Although an increase in BFB volume fraction slightly raises porosity and the number of pores, the excellent performance of BFB still greatly improves the material's mechanical properties, making it suitable for repair in complex underground environments.

Interface Bonding Performance of Ultra-High Performance Alkali-Activated Concrete Matrix and Steel Fiber

CUI Yifei, AI Weixia, ZHANG Yicong, HUANG Ting, LIU Menghua, XU Nuo, BAO Jiuwen

2025, 44(10):  3573-3586.  doi:10.16552/j.cnki.issn1001-1625.2025.0351

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In order to reduce carbon emissions and improve the comprehensive utilization rate of industrial solid waste, this paper used alkali-activated cementitious materials to prepare ultra-high performance alkali-activated concrete (UHP-AAC) matrix and analyzed the effects of different curing ages, water glass modulus, and alkali equivalent on its setting time, compressive strength, and flexural strength. Additionally, the interface bonding performance between steel fibers and UHP-AAC matrix was studied through single fiber pull-out tests, analyzing the variation rules of evaluation parameters for bonding strength. X-ray diffraction (XRD) and low-field nuclear magnetic resonance (LF-NMR) were used to analyze the reaction products and pore structure of UHP-AAC matrix, while scanning electron microscopy (SEM) was employed for the characterization of the surfaces of the pulled-out steel fibers. The results show that the increase in curing age and water glass modulus has a positive impact on the strength of matrix and the bonding performance between steel fibers and matrix. When the water glass modulus is 1.5, the compressive strength, flexural strength, and peak load at 28 d increase by 10.4%, 4.3%, and 13.3%, respectively, compared to when the modulus is 1.1. However, with the increase in alkali equivalent, a large amount of hydration products precipitate on the surfaces of the particles, leading to an increase in both macropores amounts and overall porosity, which is detrimental to the strength of UHP-AAC matrix and its interface bonding performance with steel fibers.

Pure Mode Ⅱ Shear Fracture Performance of Recycled Concrete after High Temperature

GAO Litang, MA Jiatao, TIAN Yupeng, WANG Haichao, DU Yanxin

2025, 44(10):  3587-3596.  doi:10.16552/j.cnki.issn1001-1625.2025.0446

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The shear fracture characteristics of recycled concrete under high temperatures is one of the key factors to evaluate structural safety in fires. This study prepared C30 concrete specimens with different replacement ratios of recycled coarse aggregate (0%, 50%, 100%, mass fraction). These specimens were subjected to high temperature treatments at 25~600 ℃. Shear tests were conducted using novel pure mode Ⅱ fracture specimens to systematically analyze the effects of high temperature damage and recycled aggregate on the shear fracture properties of recycled concrete. The results indicate that elevated temperature significantly reduces the fracture toughness. The fracture energy reaches its peak at 400 ℃. An increased replacement ratio of recycled coarse aggregate exacerbates the performance degradation. When the replacement ratio is 100%, the fracture energy of specimens at room temperature and 600 ℃ decreases by 20.15% and 12.69%, respectively, compared to natural concrete. The load-displacement curves exhibit more pronounced brittle failure characteristics with increasing temperature and replacement ratio. Mechanistic analysis shows that high temperature causes microcrack propagation in the interfacial transition zone (ITZ) between the cement matrix and aggregate, along with hydrate decomposition. The surface defects and high water absorption of recycled aggregate further weaken the performance of interfacial bond, promoting shear crack propagation along these weak zones. The research reveals the degradation patterns of fracture parameters under the synergistic effect of high temperature and recycled aggregate, and establishes a synergistic degradation mechanism between fracture energy and shear strength. It provides a theoretical basis for the safety assessment of recycled concrete structures after fire exposure.

Crack Resistance and Toughening Performance of Basalt Fiber Bridge Deck Concrete in Alpine Regions

GUO Yinchuan, TAN Jie, SHEN Aiqin, PEI Yunfeng, REN Guiping, ZHANG Yimiao

2025, 44(10):  3597-3608.  doi:10.16552/j.cnki.issn1001-1625.2025.0383

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In order to study the crack resistance and toughening performance of basalt fiber bridge deck concrete in alpine regions of Xinjiang, two types of curing environments, standard curing and large-temperature variation curing in alpine regions, were used indoors to study the early crack resistance of basalt fiber bridge deck concrete by means of plastic crack-resistant test and constraint ring test. An independently designed fatigue test apparatus was also used to study the fracture toughness of basalt fiber bridge deck concrete after fatigue loading. The results show that the incorporation of basalt fiber under the larger-temperature variation curing environment in alpine regions results in the suppression of plastic cracking and constraint cracking of the bridge deck concrete. When the alternating load-temperature is 150 000 times, the fracture toughness of basalt fiber bridge deck concrete is 15.76% and 17.09% higher than that of the benchmark concrete at 0.50 and 0.70 stress levels, respectively. Incorporation of basalt fiber can enhance the early crack resistance and fracture toughness of bridge deck concrete after fatigue loading in alpine regions.

Size Effect on Splitting Tensile Performance of High-Strength High-Performance Concrete after Freeze-Thaw Cycles

JIN Tangyu, PENG Shuai, YU Zhenpeng, WU Tianqian

2025, 44(10):  3609-3619.  doi:10.16552/j.cnki.issn1001-1625.2025.0385

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To investigate the effect of freeze-thaw cycles on the tensile mechanical properties size effect of high-strength high-performance concrete, a study was conducted involving the design of five freeze-thaw cycles and three specimen sizes. Using a freeze-thaw cycle equipment, a hydraulic servo machine, and digital image correlation (DIC) technology, splitting tensile mechanical performance tests were carried out after freeze-thaw cycles, allowing for the acquisition of the splitting tensile mechanical performance parameters of high-strength high-performance concrete under varying conditions. The results indicate that, with an increase in the number of freeze-thaw cycles, a gradual decline is observed in both the mass of the specimens and the relative dynamic modulus of elasticity. A progressive decrease in the tensile strength of the specimens is also noted. After 300 freeze-thaw cycles, the tensile strength reductions for specimens of 50, 75, and 100 mm in size are 15.11%, 22.60%, and 27.20%, respectively. It is demonstrated that larger specimen sizes exhibited a more significant impact from freeze-thaw cycles on the tensile strength of concrete. Furthermore, it is found that, as the number of freeze-thaw cycles increases, the size effect on the tensile strength of the concrete becomes more pronounced. Based on the classical size effect law model and the experimental results obtained, a model is proposed that considers the influence of freeze-thaw cycles on the tensile strength size effect of high-strength high-performance concrete. In addition, DIC technology is employed to analyze the damage evolution characteristics and crack expansion of concrete after freeze-thaw cycles. The research findings provide a theoretical basis for the optimization design and safety assessment of high-strength high-performance concrete structures in cold regions.

Acoustic Emission Signal Recognition of Freeze-Thaw Damage Type of Foam Concrete Based on GMM-SVM

GONG Linling, CHEN Bo, ZHOU Chengtao

2025, 44(10):  3620-3633.  doi:10.16552/j.cnki.issn1001-1625.2025.0484

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In order to understand the evolution regularity of freeze-thaw damage of foam concrete and accurately identify its damage type, uniaxial compression-acoustic emission joint tests were carried out on foam concrete with different freeze-thaw times at different loading rates. The acoustic emission signal label data were obtained by Gaussian mixture model (GMM) clustering, and the cross clusters in the data were separated by support vector machine (SVM). A new method of acoustic emission signal damage pattern recognition based on GMM-SVM algorithm was proposed. The results show that freeze-thaw action will accelerate the transformation of foam concrete failure characteristics from brittleness to ductility. The tensile stress dominates the damage mode of foam concrete in the early stage of loading, and the shear stress increases gradually with the loading process and reaches the maximum in the unstable failure stage, and the maximum decrease in the proportion of tensile cracks is 41.25%. Through the GMM-SVM algorithm, the cross-cluster of tensile-shear fracture can be accurately distinguished. It is verified that this method can correspond to different damage modes of foam concrete throughout the full loading process.

Prediction of Concrete Electric Flux Based on Machine Learning and Mix Proportion

LI Yifei, SHI Xinbo, LIN Baochen, WANG Wei, XIAO Huigang, LIU Jialin

2025, 44(10):  3634-3643.  doi:10.16552/j.cnki.issn1001-1625.2025.0221

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To address the issue of evaluating concrete transmissivity, a machine learning prediction model for concrete electric flux was developed based on known mix proportion, revealing the key influencing factors and their effect law. Using an ensemble of six machine learning algorithms, including extreme gradient boosting (XGBoost) and support vector regression (SVR), prediction models were constructed from 48 experimental datasets. The shapley additive explanation (SHAP) function was employed to analyze feature contributions. The results indicate that the XGBoost model achieves the highest prediction accuracy (R²=0.983 6), with sand content and air content identified as the primary factors influencing concrete electric flux. Data analysis shows that the electric flux reaches its minimum value at a water-binder ratio of approximately 0.4, and a sand ratio between 30.5% and 35.3% can sustain electrical conductivity at a low level. This study provides a theoretical basis and quantitative method for predicting concrete durability.

Internal Electrically Cured Concrete Temperature Field Simulation and Thermal Insulation Parameter Optimization in Negative Temperature Environment

LIU Zhongyang, CHEN Baoming, HUANG Yimiao, GU Yusen, WANG Ping, SONG Jinge, PAN Yujie

2025, 44(10):  3644-3653.  doi:10.16552/j.cnki.issn1001-1625.2025.0523

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Temperature is the key to the hardening of concrete with self-limiting heating cable-internal electric curing (SHC-IEC) in negative temperature environments, and the insulation measures are both temperature barriers and energy managers. In this paper, ANSYS and AutoCAD were used to establish a 3D mesoscopic finite element model of concrete considering random polyhedral aggregates. The effects of insulation measures on the temperature-time characteristics of SHC-IEC concrete in negative temperature environment were analyzed, and experimental verification was carried out. In addition, based on the maturity theory, the design scheme of SHC-IEC thermal insulation configuration and curing time was optimized. The results show that the 3D mesoscopic finite element model has good accuracy, and the temperature result of the finite element simulation is only 0.83 ℃ off from the experimental test result. The thickness of the insulation layer and the thermal conductivity of the insulation material significantly affect the maximum temperature and the uniformity of the temperature field of the SHC-IEC concrete specimen under negative temperature environment. When the insulation layer thickness exceeds 50 mm or the thermal conductivity of the insulation material is less than 0.05 W/(m·℃), the efficiency of temperature increase gradually decreases. Using the maturity theory, taking the 30% and 50% compressive strength values of 28 d standard curing as the benchmark, when the thermal conductivity of the insulation material is 0.032~0.149 W/(m·℃) and the insulation layer thickness is 13~380 mm, the shortest heating time is 13.089~15.605 h and 21.400~25.775 h, respectively.

Synthesis of Nano C-S-H Composite Seed Early-Strength Agent by Mechanically Assisted Wet-Chemical Method

YANG Lirong, YANG Shiwen, LI Shuaikang, WANG Shengqiang, ZHANG Huakang, LIU Zhigang, WANG Chunmei

2025, 44(10):  3654-3664.  doi:10.16552/j.cnki.issn1001-1625.2025.0480

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Sodium sulfate (Na₂SO₄) and nano calcium silicate hydrate (C-S-H) seeds can be used as early-strength agents for cement-based materials. The combination of the two can further improve the early mechanical properties of cement-based materials. In this study, analytically pure CaSO₄ and Na₂SiO₃·9H₂O were used as calcium source and silicon source, respectively, and polycarboxylate superplasticizer (PCE) was used as dispersant to prepare Na₂SO₄ and nano C-S-H composite seed early-strength agent in situ by mechanical assisted wet-chemical method. The effects of calcium-silicon molar ratio and mechanical force application time on the structure and properties of composite seed early-strength agent were investigated, and the synthesis mechanism of composite seed early-strength agent was discussed. The results show that the composite seed early-strength agent prepared by calcium-silicon molar ratio of 1.0 and mechanical force application time of 1.0 h shows lower average particle size (52.38 nm), higher stability and excellent early-strength performance. When the mechanical force application time is 1.0 h, the synergistic effect of Na₂SO₄ and nano C-S-H increases the 1 d compressive strength of high-content slag cement by 35.3%. Compared with pure nano C-S-H seed and Na₂SO₄, the addition of composite seed early-strength agent increases the 1 d compressive strength of high-content slag cement by 13.1% and 17.3%, respectively. Mechanical force can refine CaSO₄ particles, break chemical bonds, improve Ca²⁺ leaching activity, promote uniform mixing of calcium and silicon components, and collaborate with wet-chemical reactions to efficiently prepare nano composite seed early-strength agents in situ. This study can provide support for the low-cost and large-scale utilization of composite seed early-strength agents in cement-based materials.

Solid Waste and Eco-Materials

Review on Cement Solidification Treatment and Disposal Techniques of Mixed Wastes from Pb-Containing Heavy Metal Radioactive Concentrate

TAN Xiao, ZHOU Dongsheng, WANG Dong, YANG Wu, ZHOU Jiang, LIU Chunyu

2025, 44(10):  3665-3675.  doi:10.16552/j.cnki.issn1001-1625.2025.0404

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The safe treatment and disposal of nuclear waste is the core to ensure the secure recycling of nuclear energy. As the fourth-generation advanced reactor, the lead-cooled fast reactor (LFR) has become a research hotspot in the world due to its excellent safety and economy. However, for the new mixed radioactive waste of Pb-containing heavy metal radioactive concentrate generated by LFR, there are still some problems such as insufficient research on treatment technology and unclear disposal standards. Based on the cement solidification technology, this paper expounds and summarizes its fundamental principles, historical development, and research progress in the field of radioactive concentrates and Pb-containing heavy metal wastes treatment. Furthermore, based on the current research results, the key problems and development trends of cement solidification technology in the treatment and disposal of Pb-containing radioactive concentrate are deeply analyzed, aiming to provide ideas for the research and development of the cement solidification treatment and disposal technology of mixed waste from LFR.

Effect of Fly Ash on Properties of Ferroaluminate Cement Concrete under Seawater Dry-Wet Cycles

ZHANG Pu, QI Dongyou, WANG Xiaoke, XU Kaiqin, WANG Zhiyong, BI Jing, ZHANG Dong, HE Changyu, XIE Yabin

2025, 44(10):  3676-3683.  doi:10.16552/j.cnki.issn1001-1625.2025.0379

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This study aims to investigate the effect of fly ash content on the durability of ferroaluminate cement concrete under seawater dry-wet cycles. The mass loss rate, relative dynamic modulus of elasticity, and compressive strength of concrete with varying fly ash content were tested under seawater erosion conditions. Additionally, the microstructure was analyzed using XRD, SEM and mercury intrusion porosimetry. The results show that under seawater dry-wet cycles, both the mass change rate and relative dynamic modulus of elasticity of the concrete improve first and then deteriorate with the increase of fly ash content. The concrete exhibits optimal performance at a 20% (by mass) fly ash replacement level, the concrete shows optimal performance, with the mass change rate, relative dynamic modulus of elasticity, and compressive strength stabiliz after 56 seawater dry-wet cycles and remain stable through 140 seawater dry-wet cycles. At a 30% fly ash replacement level, the concrete maintains stability. In contrast, specimens with a 40% fly ash replacement level show pronounced degradation. Regarding compressive strength, an increase in fly ash content leads to a gradual decline in compressive strength. After 56 seawater dry-wet cycles, the compressive strength of concrete with 20% and 30% fly ash replacement levels remains stable. Microstructural analysis reveals that the incorporation of fly ash does not alter the main composition of hydration products but promotes the formation of ettringite. Moreover, the addition of fly ash increases the number of medium sized capillary pores and harmful pores, which negatively impacts the pore structure. However, its appropriate addition is beneficial for enhancing the chloride ion erosion resistance of concrete, thereby improving the durability of cement concrete.

Performance Degradation Mechanism of Autoclaved Fly Ash Foam Concrete under Different Cooling Methods after High Temperature

HAO Yunhong, CHEN He, SUN Hao, LIU Junguo, HAN Ping, DU Genjie

2025, 44(10):  3684-3693.  doi:10.16552/j.cnki.issn1001-1625.2025.0308

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The high temperature caused by fire and cooling methods will significantly affect the compressive performance of autoclaved fly ash foam concrete (AFAFC), thus affecting the safety of building structure. In this study, the performance of AFAFC was tested by high temperature and different cooling methods. The effects of high temperature and different cooling methods on the appearance, quality, compressive strength, porosity and microstructure of AFAFC were studied. The results show that the compressive strength of AFAFC is the highest when the fly ash content is 60% (mass fraction) at room temperature, and the optimal calcium-silicon ratio is 0.86. High temperature leads to color change and crack propagation of AFAFC. With the increase of temperature, the mass loss rate of AFAFC increases gradually, and the compressive strength increases first and then decreases. The high temperature resistance of AFAFC is the best when the fly ash content is 60% (mass fraction). After 600 ℃, the compressive strength of AFAFC60 in natural cooling state and water cooling state decreases compared with that at room temperature. The research results can provide a theoretical basis for the study of high temperature resistance of AFAFC materials.

Solid Waste and Eco-Materials

Preparation of CaA Zeolite from Circulating Fluidized Bed Coal Fly Ash and Its CO₂ Adsorption Performance

YU Xingtong, TENG Yang, ZHANG Kai

2025, 44(10):  3694-3704.  doi:10.16552/j.cnki.issn1001-1625.2025.0411

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The zeolitization treatment of coal fly ash (CFA) offers a viable approach for the resource utilization of solid waste. In this study, calcium species were selectively extracted from CFA as a calcium source for subsequent ion exchange processes. Highly crystalline zeolite A was successfully synthesized through an alkali fusion-hydrothermal method using CFA as the raw material. The structural characteristics of the synthesized zeolite were characterized using techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The experimental results demonstrate that under the conditions of pH value of 3, a liquid-to-solid ratio of 4, and an acid leaching duration of 70 min, the calcium extraction efficiency reaches 82.21% (mass fraction). Under hydrothermal treatment conditions at 90 ℃ for 12 h, cubic zeolite NaA with a specific surface area of 17.95 m²/g is synthesized. Subsequent ion-exchange treatment of the zeolite NaA yielded zeolite CaA demonstrating a substantially enhanced specific surface area of 408.32 m²/g. Under the conditions of an adsorption temperature of 25 ℃, a total gas flow rate of 80 mL/min, and a CO₂ volume fraction of 10%, the saturation adsorption capacities of zeolites NaA and CaA are measured to be 1.276 and 1.450 mmol/g. The kinetic model fitting demonstrates that zeolite CaA exhibits a higher CO₂ adsorption rate compared to NaA zeolite, which holds significant implications for carbon capture cost reduction.

Silicon Source Regulation in Steel Slag-Based Alkali-Activated Cementitious Materials and Its Strength Evolution Mechanism

SONG Yuzhang, ZHAO Qinglin, YAO Xiaojie, MA Wenjie

2025, 44(10):  3705-3712.  doi:10.16552/j.cnki.issn1001-1625.2025.0400

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In order to break through the key technical barriers of poor cementitious properties of steel slag and realize the resource utilization and high value-added utilization of steel slag, this paper uses a large amount of steel slag as the main raw material, and uses alkali activator to stimulate the cementitious properties of steel slag. At the same time, appropriate silicon sources are introduced and the ratio of cementitious materials is optimized to reduce the activator content. The results show that in the steel slag-slag binary system, when the steel slag content is 60% (mass fraction, the same below) and the activator content is 17%, the compressive strength of the system is the largest, which is 74.2 MPa. When silica fume is introduced as silicon source, the activator content decreases from 17% to 11%, and the compressive strength of the system can still reach 72.7 MPa. When quartz powder is introduced as silicon source, the compressive strength of the system decreases to 63.7 MPa. Compared with the microstructure of the system with an activator content of 17%, when the activator content is reduced to 11%, the generated number of hydrated calcium silicate (C-S-H) gels in the system changes very little after the introduction of silica fume, and the internal structure is highly dense. The main reason is that silica fume, as a silicon source material, can provide corrosion-type SiO^2-₃ to participate in the formation of C-S-H gels, thereby forming sufficient compressive strength. After the introduction of quartz powder, the activity of quartz powder has not been effectively activated under the condition of humid-heat-treating at 60 ℃, and it is dominated by filling effect in the system, resulting in a certain degree of reduction in the generated number of C-S-H gels and the density of internal structure.

Influence of Pore Structure on Transport Properties of AASF Mortar under Carbonation Curing

ZHENG Dapeng, YANG Jianxiang, ZHAO Debo, CUI Hongzhi

2025, 44(10):  3713-3724.  doi:10.16552/j.cnki.issn1001-1625.2025.0348

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Alkali-activated materials, as a novel low-carbon and eco-friendly cementitious material, has attracted significant attention. However, the quantitative relationship between its pore structure and transport properties, which is closely related to durability, remains unclear. To clarify the influence mechanism of pore structure variations on the transport properties of alkali-activated materials, this study employed high-humidity carbonation curing to regulate the microstructure. The effect of carbonation curing on the mechanical properties, pore structure, and transport properties (gas permeability and surface capillary water absorption rate) of alkali-activated slag-fly ash (AASF) mortar was explored. Results demonstrate that carbonation curing changes the distribution of microscopic pore structure. The filling of carbonation products lead to a more uniform pore distribution in both small-pore region (<100 nm) and transitional-pore region (100~10 000 nm), significantly decreasing material transport properties. Gas permeability exhibits a multiplicative reduction, and the capillary water absorption rate even decreases by 66.66% for the sample with 40% (mass fraction) fly ash, thereby contributing to enhanced durability of AASF mortar.

Anti-Chloride Ion Permeability of Alkali-ActivatedSlag-Fly Ash Concrete

CHEN Linlu, CHEN Xin, LI Jiaxu, WANG Hongfeng

2025, 44(10):  3725-3733.  doi:10.16552/j.cnki.issn1001-1625.2025.0554

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This paper focused on optimizing the anti-chloride ion permeability of alkali-activated slag-fly ash (AASF) concrete. The electric flux method was used to test anti-chloride ion permeability, combined with SEM microstructure analysis, systematically studied the mechanism and influences of various variables on the anti-chloride ion permeability of concrete with fly ash content, alkali equivalent (calculated as Na₂O equivalent), water glass modulus and water-binder ratio as the key control variables. The results show that the electrical flux value of the test specimen is only 763.87 C under the conditions of a mix ratio of 25% (mass fraction) fly ash, 5% alkali equivalent, 1.2 water glass modulus, and 0.40 water-binder ratio, which is 58.20% lower than that of the benchmark cement-based concrete. This verifies that the AASF concrete with this mix ratio has the optimal anti-chloride ion permeability. A chloride ion permeation model with fly ash content as the main influencing factor was established based on the above test results and Fick's second law. The calculated value of chloride ion diffusion coefficient has an error of within ±5% compared to the measured value after comparing and analyzing with the test results.

Performance Optimization of All-Solid Waste Non-AutoclavedAerated Concrete

YAO Xianhua, HAN Linyan, LIU Li, LI Zhicheng, WAN Mingduo, LIU Shiwen, CHEN Shengqiang, SHANGGUAN Linjian

2025, 44(10):  3734-3746.  doi:10.16552/j.cnki.issn1001-1625.2025.0443

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In this study, carbide slag was used to replace lime to prepare all-solid waste non-autoclaved aerated concrete. The effects of main process parameters such as calcium-silicon ratio (Ca/Si), water-binder ratio (W/B), alkali activator modulus (M), hydroxypropylmethyl cellulose (HPMC) content and curing conditions on the physical and mechanical properties such as fluidity, foaming curve, cross-sectional pore, water absorption, dry density and compressive strength of non-autoclaved aerated concrete were studied. The hydration products and microstructure of all-solid waste non-autoclaved aerated concrete were analyzed by XRD and SEM. The results show that with the increase of W/B, M and HPMC content, the compressive strength and dry density of all-solid waste non-autoclaved aerated concrete specimens increase first and then decrease. With the increase of Ca/Si, the compressive strength and dry density of all-solid waste non-autoclaved aerated concrete specimens decrease first and then increase. When all-solid waste non-autoclaved aerated concrete obtains good pore structure, good physical and mechanical properties, the optimum process parameters are: Ca/Si of 0.76, W/B of 0.5, M of 1.0, HPMC content of 0.6% (mass fraction), curing temperature of 70 ℃. The main hydration products (calcium silicate hydrate (C-S-H) gel and ettringite) of all-solid waste non-autoclaved aerated concrete after high temperature steam curing are the main providers of concrete strength. C-S-H gel and ettringite make the internal structure of aerated concrete denser.

Road Performance Research and Application of Stabilized Silt Subgrade with Slag-Based Cementitious Materials

WU Weijun, DING Beidou, ZHANG Kunpeng

2025, 44(10):  3747-3760.  doi:10.16552/j.cnki.issn1001-1625.2025.0482

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In this study, alkali-activated cementitious materials were developed through the synergistic activation of ground blast furnace slag (GGBS) with calcium hydroxide (Ca(OH)₂) and sodium sulfate (Na₂SO₄) for silt improvement. Cement stabilization was employed as a control group to address the deficiencies of poor gradation and low strength in silt when used as roadbed filler. Single-factor experiments were conducted to determine the optimal dosage ranges of the three curing materials, and the mix ratio of the composite curing agent was further optimized using the response surface methodology. Additionally, laboratory mechanical property tests were performed on solidified silt to investigate the influence of varying dosages of solidifying agents on the unconfined compressive strength, split tensile strength, and California bearing ratio (CBR) of solidified silt at different curing ages. Based on the laboratory findings, field trials were carried out on solidified silt subgrade fillers for the Anyang-Luoshan expressway section. The results confirmed that the silt subgrade stabilized with the composite curing agent exhibited excellent road performance. Test results indicates that the optimal mass mix ratio of slag, calcium hydroxide, and sodium sulfate is 19.75:10.86:1. The unconfined compressive strength and splitting tensile strength of the composite-stabilized soil increases with both the curing age and the dosage of the curing agent. The CBR value of the composite-stabilized soil with a 4% (mass fraction) dosage reached 27.96%, satisfying the bearing ratio requirements and being approximately 17.95% higher than that of the cement-stabilized soil with the same dosage. The compaction degree, dynamic cone penetrometer index (DCPI), CBR value, and deflection value of the test section of the slag-based solidified silt subgrade met the design specifications, demonstrating good application effects. This approach can be widely promotes for silt subgrade fillers.

Prediction and Optimization of Solidified Soil Performance Using Solid Waste-Based Cementitious Materials on Neural Network

YUAN Huihui, DENG Jiaxin, YU Ben, ZHANG Xiaoxiang, GU Lei, YANG Jianhui, HAN Shuang

2025, 44(10):  3761-3772.  doi:10.16552/j.cnki.issn1001-1625.2025.0303

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With the acceleration of urbanization, the problem of waste soil management is becoming more and more serious. In this paper, a soil solidification method based on solid waste-based cementitious materials was proposed. Using ground granulated blast furnace slag, steel slag and desulfurization gypsum as curing agents, the effects of different mix ratios on the unconfined compressive strength (UCS) of sandy silt were studied by mixture design, and the UCS prediction model of solidified soil was established by artificial neural network (ANN). The results show that the solid waste-based cementitious materials significantly improve the early and late UCS of solidified soil, especially when the steel slag content is not higher than 30% (mass fraction), the UCS of the solidified soil is better than that of the cement solidified soil. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis show that the hydration products ettringite (AFt) and hydrated calcium silicate (C-S-H) gel fill the soil pores and improve the compactness and mechanical properties of the solidified soil. The coefficient of determination R² of the 7 and 28 d UCS prediction models based on ANN is above 0.95, showing high prediction accuracy. Through the analysis of characteristic importance, the influence of solid waste-based cementitious materials content and soil water content on UCS of solidified soil are the more significant. The research results provide a theoretical basis for the mix proportion optimization and engineering application of solid waste-based cementitious materials.

Effects of Compounding Mineral Admixtures on High-Temperature Resistance of Magnesium Potassium Phosphate Cement

LI Shuichang, HUANG Chen, MO Shimin, ZHAO Xicheng

2025, 44(10):  3773-3780.  doi:10.16552/j.cnki.issn1001-1625.2025.0316

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In order to investigate the synergistic improvement of the high-temperature resistance of magnesium potassium phosphate cement (MKPC) by compounding fly ash and silica fume. In this paper, the compressive strength tests of MKPC at four temperatures (25, 400, 600 and 800 ℃) were conducted by varying the relative content of compounding fly ash and silica fume. The appearance, mass loss and compressive strength of MKPC treated at different temperatures were investigated. Additionally, the phase composition and microstructure of MKPC were analyzed using X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The results indicate that after exposure to high-temperatures, the mechanical properties of MKPC without fly ash and silica fume decrease sharply, while specimens with 15% or 10% (mass fraction) silica fume show significant improvement. When the mass fractions of fly ash and silica fume are 5% and 15%, respectively, the mechanical properties of MKPC after high temperature are better. The high-temperature dehydration of K-struvite (MgKPO₄·6H₂O), the hydration product of MKPC, is the main reason for the mass loss and compressive strength reduction of MKPC. Silica fume and fly ash can promote the sintering of the phase and amorphous particles after the decomposition of K-struvite to form a ceramic-like structure, thereby improving the high-temperature resistance of MKPC. Interestingly, the improvement of silica fume on the high-temperature resistance of MKPC is greater than that of fly ash.

Effect of Strengthening Brick-Concrete Mixed Recycled Aggregate on Properties of Its Geopolymer Concrete

TIAN Aiping, CHEN Shuye, ZHANG Lin, FAN Qiqi, YANG Xuming, ZHOU Yingtao, LIU Heng, FENG Xingguo

2025, 44(10):  3781-3790.  doi:10.16552/j.cnki.issn1001-1625.2025.0447

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Resource utilization of solid waste is a key pathway toward achieving green and low-carbon development. In response to the challenges of difficult separation and significant performance differences between brick-concrete mixed construction waste, this study employed slurry coating pretreatment to enhance the properties of brick-concrete mixed recycled aggregates. Geopolymer binders were prepared using fly ash and slag, and the mechanical properties of geopolymer recycled concrete with various mix proportions were investigated. The results indicate that when the content of recycled brick aggregate does not exceed 15% (mass fraction), its impact on concrete compressive strength is negligible, however, compressive strength decreases significantly when the proportion exceeds this threshold. Slurry coating pretreatment improves the compactness of the interfacial transition zone (ITZ), leading to a 10.45% increase in compressive strength compared with control group. Furthermore, increasing fly ash content and the modulus of the alkali activator negatively affects concrete (mass fraction) strength. Based on a comprehensive analysis, it is recommended to limit the recycled brick aggregate content to no more than 15%, apply cement paste-slag geopolymer slurry for pretreatment, use fly ash content below 20% (mass fraction), and set the alkali activator modulus around 0.8. The optimized mix is successfully applied in a hydraulic engineering field trial, where the 28 d compressive strength reaches 36.7 MPa, confirming the technical feasibility and environmental benefits of this approach.

Solidification of Phosphorus and Fluorine in Phosphogypsum and Its Effect on Properties of Mine Filling Materials

CHEN Yanlong, ZHOU Yingying, FANG Keneng, CHEN Yiheng, CHEN Qianlin

2025, 44(10):  3791-3804.  doi:10.16552/j.cnki.issn1001-1625.2025.0433

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This study focused on the solidification of soluble phosphorus and fluorine impurities in phosphogypsum and its effect on the properties of filling materials. The effects of Ca(OH)₂ content, coal gasification slag (CGCS) content and particle size, free water content, and placement time on the solidification efficiency of soluble phosphorus and fluorine in phosphogypsum were investigated, with the solidification mechanism elucidated through SEM-EDS analysis. Subsequently, both untreated and solidified phosphogypsum were utilized as the primary raw material, supplemented with ordinary Portland cement (OPC) and fly ash (FA), to prepare phosphogypsum-based mine filling materials. The results show that CGCS reduces the total fluorine concentration in the toxic leachate of phosphogypsum and synergistically enhances the solidification of soluble fluorine by Ca(OH)₂. The compressive strength of filling materials prepared from solidified phosphogypsum is significantly increased from 0.25 MPa to 2.54 MPa, while the softening coefficient rises from 0 to 0.85 after 28 d of natural curing. XRD and SEM-EDS analyses further confirm that effective solidification of phosphorus and fluorine significantly promotes the hydration reactions of OPC and FA. Solidification of soluble phosphorus and fluorine impurities in phosphogypsum is a key approach to significantly enhance the mechanical properties and water resistance of filling materials.

Ceramics

Effect of B₄C Content on Densification and Mechanical Properties of Non-Equimolar Quinary Boride Ceramics

WANG Kun, QIU Shuaihang, ZOU Ji, JI Wei, WANG Weimin, FU Zhengyi

2025, 44(10):  3805-3813.  doi:10.16552/j.cnki.issn1001-1625.2025.0521

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In this paper, (Ti_0.1Zr_0.35Hf_0.35Nb_0.1Ta_0.1)B₂ composite ceramics were prepared by pressureless sintering process with B₄C as sintering aid. The microstructure and mechanical properties of samples sintered at 1 900~2 200 ℃ with different content of B₄C were investigated. The results show that the introduction of B₄C can significantly promote the densification of ceramics. At 2 100 ℃, ceramic samples with 2 % and 5 % (mass fraction) B₄C achieve near-complete densification, and the hardness and fracture toughness of materials are improved at lower sintering temperatures (2 000~2 100 ℃). The composite ceramics with 5% B₄C addition sintered at 2 100 ℃ show good mechanical properties, with a hardness of (21.49±1.17) GPa and a fracture toughness of (3.12±0.11) MPa·m^1/2. However, when the sintering temperature rises to 2 200 ℃, B₄C forms a liquid phase, resulting in a decrease in densification and mechanical properties of material. This study provides reference for the design of complex component ceramics composition, the regulation of sintering aid and the establishment of pressureless sintering densification window.

Glass

Research Progress on Pt-Channel Technology Development in OLED Substrate Glass Production

ZHI Jiaoyao, HE Feng, ZHAO Zhilong, TIAN Yingliang, ZHAO Zhiyong

2025, 44(10):  3814-3825.  doi:10.16552/j.cnki.issn1001-1625.2025.0544

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With the iterative progress of intelligent terminals, organic light emitting diode (OLED) displays show a trend of large size and flexibility. This development trend not only propels OLED substrate glass to make breakthroughs in larger sizes, ultra-thin and flexible foldability, but also promotes the innovation of its core manufacturing equipment—Pt-channel technology. As a key piece of equipment for fining and homogenization molten glass, the Pt-channel plays a core role in improving the yield rate and performance of OLED substrate glass. Through the review of relevant literature, this paper comprehensively summarizes the development history of OLED substrate glass and the current research status of Pt-channel technology. It focuses on comparing and summarizing the structural forms and process characteristics of Pt-channels, analyzes their future development directions, and provides references for the development and structural improvements of Pt-channel technology in OLED substrate glass production.

Effects of Alkaline Earth Metal Oxides on High-Temperature Melt Properties of OLED Substrate Glass

TIAN Yingliang, WANG Zhongyu, LI Zhifeng, ZHAO Zhiyong

2025, 44(10):  3826-3832.  doi:10.16552/j.cnki.issn1001-1625.2025.0452

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The properties of high-temperature melts not only affect the melting and preparation of organic light-emitting diode (OLED)substrate glass but also influence the performance and service life of OLED devices. In this paper, alkali-free aluminoborosilicate glass was taken as the research object, and the influence of SrO/MgO molar ratio on the properties of high-temperature melts of OLED substrate glass (high-temperature viscosity, high-temperature resistivity, and surface tension) was systematically explored. The results show that with the increase of the SrO/MgO molar ratio, the high-temperature viscosity of the glass melt shows a nonlinear change, and when the SrO/MgO molar ratio is 3.31, the high-temperature viscosity reaches a maximum value. The high-temperature resistivity of the melt at 1 600 ℃ is increased by an average of 32.22%, and the melt surface tension decreases by an average of 2.47%. This study provides a scientific basis for optimizing key process performance of OLED substrate glass and has important guiding significance for industrial production and manufacturing.

Numerical Simulation of OLED Display Glass Overflow Process Forming

GUO Hongwei, LIU Mi, ZHU Nantian, NIE Dong, YANG Hailong, ZHAI Ziliang, ZHAO Zhilong

2025, 44(10):  3833-3843.  doi:10.16552/j.cnki.issn1001-1625.2025.0416

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As the core technology of the glass forming in high generation organic light-emitting diode (OLED) displays, the parameter configuration of the overflow downdrawing method determines the flow behavior of the glass liquid and the forming quality. In this study, the effects of inlet channel depth, distal channel depth and glass melt density on the thickness of glass liquid on the overflow surface, the velocity distribution and the velocity field distribution inside the overflow tank during the overflow process were systematically investigated using Fluent software. The results show that, with the increase of the inlet channel depth, the overflow of glass liquid at the proximal end decreases, leading to the reduction of flow velocity and thickness, while the velocity and thickness at the distal end are enhanced due to the accumulation of kinetic energy. With the increase of the distal channel depth, the flow of glass liquid at the distal end increases rapidly, and the velocity and thickness of the glass liquid increase significantly, while that of glass liquid at the proximal end decreases. The increase of the glass melt density makes the thickness and velocity of the glass liquid decrease at the proximal end, but the thickness and velocity of glass liquid remain unchanged and the velocity of glass liquid at the distal end increase. The increase of glass liquid density decreases the thickness and velocity of the proximal glass liquid, but the velocity of the distal glass liquid increases. Based on the multi-parameter synergistic control, when the inlet velocity is 0.015 m/s, the inlet is 100×100 mm, the tank width is 200 mm, and the wall thickness is 50 mm, the optimization scheme is proposed: the inlet tank depth H=253 mm, the distal tank depth h=30 mm, and the glass melt density ρ=2 440 kg/m³, which can achieve the smoothing of the velocity gradient between the near and far ends, and reduce the thickness difference to 0.205 mm, and provide theoretical support for the optimization of the design and process optimization of overflow trough.

Defect Formation and Performance Degradation Law of Quartz Glass in Neutron-Gamma Composite Radiation Fields

LI Li, FAN Lianbin, YANG Bo, WANG Xicheng, WU Xinjian, XING Long

2025, 44(10):  3844-3852.  doi:10.16552/j.cnki.issn1001-1625.2025.0513

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This study investigated the optical performance evolution law and applicability of quartz glass in low dose rate radiation environments through composite irradiation based on real-condition radiation fields. The spectral transmittance of quartz glass was measured across 200~2 000 nm. The results indicate that as the irradiation dose increases, the transmittance and absorption of quartz glass in the visible and near-infrared bands remain unchanged, while in the ultraviolet band (200~400 nm), light absorption significantly increases, and transmittance decreases with higher irradiation doses. In addition to the intrinsic defects such as oxygen vacancies (5.1 eV) and Si—E′ centers (6.1 eV), composite irradiation induces the formation of peroxy peroxygen-linked defects with a central wavelength of 4.3 eV in quartz glass. Under shortened mission durations conditions, the transmittance degradation of quartz glass in low-dose-rate radiation environments fully meets the optical performance requirements for fiber processing equipment and industrial robot vision inspection systems.

Functional Materials

Performance Analysis of Y³⁺-Doped Na₃Zr₂Si₂PO₁₂ Solid-State Electrolytes for Solid-State Sodium Batteries

WANG Yuanyuan, LI Yan, WANG Qi, LI Haichen, HAN Shuangshuang

2025, 44(10):  3853-3863.  doi:10.16552/j.cnki.issn1001-1625.2025.0432

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Sodium ion batteries have become a research hotspot in the field of energy storage due to their low cost and relatively high energy density. However, traditional liquid-state electrolytes have potential safety hazards such as leakage and flammability, and it is urgent to develop stable and reliable solid-state electrolytes. In this study, a series of Na_3+xZr_2-xY_xSi₂PO₁₂ (x=0, 0.05, 0.10, 0.15) solid-state electrolytes were prepared by Y³⁺ heterovalent doping Na₃Zr₂Si₂PO₁₂ to improve its compactness, ionic conductivity, and interface stability. The samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the appropriate amount of Y³⁺-doping (x=0.10) significantly improves the density (91.93%) and room temperature ionic conductivity (8.91×10^-4 S·cm^-1) of NASICON-type Na₃Zr₂Si₂PO₁₂ without destroying the crystal structure. The Y³⁺-doped samples have smaller interface polarization voltage and impedance growth rate, showing excellent interface stability. The solid-state sodium battery assembled based on Na_3.10Zr_1.90Y_0.10Si₂PO₁₂ has a capacity retention rate of 98.55% after 100 cycles at 0.1 C at room temperature. This study reveals the synergistic regulation of Y³⁺-doping on crystal structure and interface behavior, which provides an important reference for the design and interface optimization of sodium ion solid-state electrolyte materials.

Preparation of Nickel Sulfide/Carbon Composite Materials and Their Sodium Storage Performance

MENG Xudong, WANG Siyan, QUAN Bo, JIN Aihua

2025, 44(10):  3864-3872.  doi:10.16552/j.cnki.issn1001-1625.2025.0345

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The electrochemical performance of nickel sulfide composite materials were systematically investigated as anode materials for sodium-ion batteries (SIBs). To address the challenges of volume expansion and poor cycle stability in nickel sulfide materials in practial applications, nickel sulfide particles were treated by high energy ball mill method, and carbon-coated nickel sulfide (Ni₃S₂/BM/C) composites were prepared. Ni₃S₂/BM/C composite materials exhibit reversible capacity of 378.7 mAh·g^-1 after 100 cycles at a current density of 200 mA·g^-1. This performance is significantly higher than that of commercial Ni₃S₂ (163.4 mAh·g^-1). The excellent electrochemical performance of Ni₃S₂/BM/C composite materials originate from their unique structural advantages: the nanoscale particle size effectively alleviates volume expansion during charge/discharge cycles, while the uniform carbon-coating enhances electrical conductivity and plays a crucial role in long-term cycling stability. This study not only presents a promising strategy for the implementing of nickel sulfide composites in SIBs, but also provides reference for developing advanced SIBs negative electrode materials.

Preparation and Performance of High-Performance LSFT-GDC Composite Electrode

DONG Hao, CAO Zhiqun, LI Na, WEI Zhaotong

2025, 44(10):  3873-3879.  doi:10.16552/j.cnki.issn1001-1625.2025.0328

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Solid oxide fuel cells (SOFCs) have attracted extensive attention due to their exceptional efficiency, wide fuel selection, and low environmental pollution compared to conventional power generation systems. In this study, composite electrode materials comprising perovskite oxide La_0.3Sr_0.7Fe_0.7Ti_0.3O₃ (LSFT) and oxygen-ion conductor Gd_0.2Ce_0.8O_2-δ (GDC) were synthesized via the sol-gel method for application as both cathode and anode in symmetric solid oxide fuel cells (SSOFCs).The results show that the composite electrodes prepared with different mass ratios of LSFT and GDC exhibit good chemical compatibility. At 800 ℃, the symmetric cell using LSFT-GDC composite electrode (the mass ratio of LSFT and GDC is 6:4) achieves a polarization resistance of approximately 0.28 Ω·cm² (under humidified hydrogen atmosphere), with a maximum power density of 286 mW·cm^-2, demonstrating an excellent electrochemical performance. This enhanced performance is attributed to the LSFT composited with ionic conductor GDC, which extends the triple-phase reaction interface of the electrode material and improves catalytic activity for both oxygen reduction and hydrogen oxidation reactions. Furthermore, the symmetric cell demonstrates exceptional stability during a 24 h operational test in wet hydrogen atmosphere without performance degradation and maintained consistent electrochemical properties through 5 oxygen reduction cycles.

Synergistic Mechanism of KCl-Modified Graphitic Carbon Nitride for Photocatalytic Degradation of Methylene Blue

ZHAO Meixuan, WEI Menglan, WANG Yimeng, TENG Fei, OU Xiaoxia

2025, 44(10):  3880-3890.  doi:10.16552/j.cnki.issn1001-1625.2025.0415

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Using graphitic carbon nitride (g-C₃N₄) as a support, KCl-doped X%-KCl/g-C₃N₄ photocatalysts (X=5, 10, 15) were synthesized via mechanical grinding-thermal polycondensation, photocatalytic performance of g-C₃N₄ was optimized by turning the KCl doping ratio and a synergistic mechanism system involving “band structure-carrier separation-free radical generation” was conducted. The X%-KCl/g-C₃N₄ samples were systematically characterized by UV-Vis DRS, FT-IR, XRD, EPR, EIS and PL, and their methylene blue (MB) degradation performance under solar light was evaluated. The results indicate that the 10%-KCl/g-C₃N₄ photocatalyst exhibits outstanding degradation performance, under sunlight irradiation, achieving a 97.12% degradation efficiency for 10 mg/L MB within 120 min at a catalyst dosage of 1 g/L. The first-order reaction rate constant (0.022 9 min^-1) is 1.97 times higher than that of pristine g-C₃N₄ (0.011 6 min^-1). The work provides a novel strategy for designing non-metal-modified photocatalysts with high efficiency and sustainability.