Table of Content

Volume 45 Issue 8
15 August 2026

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Cement and Concrete

Research Progress on Interlayer Bond Strength of 3D Printed Concrete

HE Zhimin, CHEN Xince, LU Bowen, ZHANG Guixin, LIU Junzhe

2026, 45(8):  2583-2599.  doi:10.16552/j.cnki.issn1001-1625.2026.0115

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In extrusion-based 3D printed concrete （3DPC）， due to the layer-by-layer stacking process， interlayer bond strength is a key factor affecting the overall structural performance.This paper systematically reviews the latest research progress on the interlayer bond strength of 3DPC. Firstly， from a materials perspective， the regulatory mechanisms of cementitious material mix proportion， aggregates， admixtures， fibers， and nanomaterials on interfacial performance are analyzed. Secondly， from a processing standpoint， the influence patterns of printing parameters and curing temperature and humidity， and other factors are discussed， and the strengthening effects of chemical bonding agent spraying and physical enhancement techniques are summarized. Furthermore， the applicability and limitations of macroscopic mechanical testing methods—such as interlayer direct tensile， splitting tensile， and shear tests—are critically compared. These methods are reviewed in conjunction with recently released industry standards. The application of microscopic characterization techniques， including scanning electron microscopy and nanoindentation， as well as non-destructive testing methods， in studying interfacial bonding mechanisms is also reviewed. Finally， the paper identifies current research gaps， particularly regarding the coupled effects of multiple factors and long-term durability， and proposes future research directions for enhancing interlayer bond performance.

Influence of Ferrite Phase Content on Erosion Resistance of Ferrite-Aluminate Cement

LI Hongxuan, WANG Yali, PEI Tianrui, WANG Zhiyong, QI Dongyou

2026, 45(8):  2600-2611.  doi:10.16552/j.cnki.issn1001-1625.2026.0143

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Ferrite-aluminate cement holds significant application prospects in marine engineering due to its low clinkering temperature， reduced carbon emissions， and excellent erosion resistance. In this study， four cement samples with different ferrite phase content were prepared. Immersion tests in chloride and sulfate solutions were conducted， and the influence of ferrite phase content on erosion resistance was systematically investigated using analytical techniques such as XRD， TG， MIP， and SEM. The results indicate that as the ferrite phase content increases， the cement exhibits a lower chloride diffusion coefficient， enhanced chloride-binding capacity， and significantly improved sulfate resistance. When the proportions of the main minerals C₄A₃S， C₂S， and ferrite phase all approach 30%， the cement demonstrates optimal erosion resistance. Its dense structure and low porosity， along with the synergistic effects of ettringite， ferric gel， and aluminate gel in the hydration products， effectively impede ion penetration and enhance durability.

Optimization of D-Mannitol-Modified Magnesium Phosphate Cement Properties Using Response Surface Methodology

WANG Qiuao, CHEN Feng, PENG Jinying, LI Yue, QIAN Shanshan

2026, 45(8):  2612-2623.  doi:10.16552/j.cnki.issn1001-1625.2026.0255

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Magnesium phosphate cement （MPC） is formed by magnesium-based raw materials （whose main components include magnesium oxide or magnesium hydroxide）， phosphates， and retarders. MPC exhibits excellent performances such as rapid setting and hardening， high early strength， superior bonding capability and good volume stability， and it has been widely applied in road rapid repair， airport runway maintenance and special structural rehabilitation. Nevertheless， the traditional retarder borax causes obvious early strength deterioration of MPC when it is incorporated， and it fails to achieve a good balance between working performance and mechanical strength. Moreover， most new retarders still exert adverse impacts on the early mechanical properties of MPC， so their retarding effect and strength development could not be coordinated well. To address the above deficiency， this study adopted response surface methodology to explore the synergistic influence and regulation mechanism of D-mannitol and borax compound system on MPC performances.

Borax and D-mannitol content were selected as experimental variables， both ranging in mass fraction from 2.50% to 5.01%. A two-factor， five-level central composite design was adopted， and quadratic polynomial regression models were established to correlate borax content and D-mannitol content with setting time， 1 d flexural strength， and 1 d compressive strength. Variance analysis results indicate that all regression models were highly significant， with high coefficients of determination and low coefficients of variation， demonstrating satisfactory fitting accuracy and predictive reliability of the models. Experimental results show that the retarding effect of D-mannitol is more pronounced at a low borax content of 2.50%~3.50% by mass. At a high borax content of 4.50%~5.01% by mass， the early strength initially increases and then decreases with rising D-mannitol content. By contrast， strength declines monotonically as D-mannitol content increases at low borax content. The optimal mix proportion is obtained by model optimization： borax content is 2.50% and D-mannitol content is 4.78%. Under this optimal proportion， the measured setting time is 29.0 min， the 1 d flexural strength is 8.6 MPa， and the 1 d compressive strength is 48.1 MPa. Multiple characterization analyses show that in the optimized composite system， D-mannitol reduces the agglomeration of magnesium oxide particles through its dispersion effect， whereas borax acts as a retarder by forming a protective film on the surfaces of magnesium oxide particles. This dispersion-film formation effect regulates pH evolution， thereby reducing the early hydration rate of MPC. Meanwhile， the optimized composite system accelerates the dissociation of the protective film at specific hydration stages， exposes active sites on magnesium oxide particle surfaces， enhances the generation of hydration products， improves the density of the matrix， and effectively promotes the early strength development of MPC.

This study clarifies the synergistic mechanism of D-mannitol and borax， and provides theoretical support and technical reference for the application of D-mannitol-modified MPC.

Hydration Kinetics Model and Mechanical Property Prediction of Limestone Powder-Slag-Cement (LS³) Binder System

WU Lang, PAN Wenxin, HU Jiaxin, LEI Bin, AI Jianping

2026, 45(8):  2624-2636.  doi:10.16552/j.cnki.issn1001-1625.2026.0220

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Utilizing slag and limestone powder as issueary cementitious materials in cement-based composites has become increasingly widespread due to their low cost and low-carbon characteristics. When combined with cement， they exhibit synergistic reactions that enhance the mechanical properties of concrete. To establish an integrated hydration-strength optimization model for the limestone powder-slag-cement （LS³） ternary composite binder system， this study developed an integrated hydration-strength prediction model that couples chemical reactions， microstructural evolution， and macroscopic mechanical behavior to simulate the hydration process and calculate the reaction degrees of individual components. The Bernard-Ulm-Lemarchand model was employed to analyze the evolution of phase volume fractions during hydration. Combined with the degree of reaction， mixture proportions， and Powers’ theory， the relationship between gel-space ratio and compressive strength was established. Response curves of concrete strength were then obtained through parametric analysis. The results indicate that limestone powder dominates early age （2 d to 7 d） strength development， whereas slag acts as the main driver for laterage （90 d to 360 d） strength growth. It is proposed that a limestone powder content of 8% to 12% and a slag content of 15% to 25% constitute the optimal range for balanced strength development across all ages in this system. The predicted compressive strengths show a correlation coefficient of 0.95 with experimental values and a root mean square error of 1.35 MPa. The model predictions agree well with independent test data. This study provides a theoretical model and computational basis for the precise design and engineering application of low-carbon cementitious materials.

Terahertz Time-Domain Spectroscopy of Calcium Silicate Hydrates with Varying Calcium-to-Silicon Ratios

LI Zhanguo, CHEN Ying, LI Yue, LI Xiangyu

2026, 45(8):  2637-2649.  doi:10.16552/j.cnki.issn1001-1625.2026.0083

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Calcium silicate hydrate （C-S-H） is the main binding phase of hydrated Portland cement and largely determines strength and durability of concrete. It is nanocrystalline and mostly amorphous， with short-range order but no long-range periodicity. The medium-range order （MRO） that connects these two scales is thought to control the mechanical and transport behaviour of concrete， yet it is hard to measure， and the link between the nanostructure of C-S-H and its properties is still poorly understood. The boson peak， an excess of low-frequency vibrational states common to disordered solids， reflects both the MRO and the nanoscale fluctuation of elastic constants. For C-S-H it has been predicted by molecular-dynamics simulations but not yet measured. Terahertz （THz） radiation （0.1 THz to 10 THz） lies in the frequency range of these collective vibrations， so terahertz time-domain spectroscopy （THz-TDS） can be used to probe the boson peak directly.

C-S-H gels with nominal calcium-to-silicon molar ratios （Ca/Si） of 0.5， 0.8， 1.0， 1.4， and 1.7 （actual values 0.54 to 1.74 after impurity correction） were synthesized hydrothermally under nitrogen. They were characterized by X-ray diffraction （XRD）， Fourier-transform infrared spectroscopy （FTIR）， thermogravimetric analysis （TGA）， X-ray fluorescence， laser particle sizing and helium pycnometry， which revealed a poorly crystalline tobermorite-like gel with turbostratic stacking， and provided the contents of water and impurities （portlandite and calcite）. THz-TDS spectra were recorded in transmission on HDPE-diluted pellets over 0.4 THz to 3.0 THz， and the complex refractive index， absorption coefficient and dielectric function were obtained. To isolate the response of the gel itself， the dielectric contributions of the crystalline impurities were removed with an effective-medium （Bruggeman-Hanai-Sen） model， using volume fractions taken from XRD and TGA. For the measured particle sizes， the 1.0 THz to 1.5 THz range falls within the Rayleigh （weak-scattering） regime， so the spectral features come from intrinsic lattice dynamics rather than from particle scattering.

The intrinsic refractive index （1.58 to 1.85） and the real part of the permittivity show little dispersion， indicating that the water in C-S-H is nano-confined or chemically bound； FTIR showed the Si—O band shifting to lower wavenumber and broadening as Ca/Si increased， consistent with depolymerization of the silicate chains. After the dielectric loss was normalized， every sample showed a broad boson peak near 1 THz （0.82 THz to 1.02 THz）， close to values reported for silicate glasses and to the molecular-dynamics prediction for C-S-H. Its intensity varied non-monotonically with composition， peaking at Ca/Si=1.0 and decreasing on both sides of this ratio. This same composition also corresponds to an inflection in the structural-water loss （200 ℃ to 350 ℃） and the narrowest XRD diffuse peak， marking a structural crossover at Ca/Si≈1.0 from a regime governed by silicate-chain connectivity to one governed by interlayer calcium. The boson-peak frequency corresponds to a medium-range dynamical correlation length of about 1.0 nm to 1.5 nm.

These measurements provide experimental evidence of a boson peak in C-S-H and link its strength to the Ca/Si-dependent medium-range order and elastic heterogeneity of the gel. The terahertz boson peak therefore offers a way to probe the low-frequency dynamics of C-S-H that complements the usual static structural methods.

Effects and Mechanism of Internally Incorporated Calcium Stearate Emulsion on Properties of Concrete

ZHANG Xiang, WANG Yufeng, LEI Zhen

2026, 45(8):  2650-2663.  doi:10.16552/j.cnki.issn1001-1625.2026.0182

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To systematically investigate the influence law and mechanism of internally incorporated calcium stearate emulsion on the properties of concrete， concrete specimens with water-cement ratios of 0.4 and 0.5 and effective calcium stearate emulsion dosages of 0%， 0.5%， 1.0%， and 2.0% （mass fraction） were prepared. Comprehensive tests were conducted on workability， mechanical strength， pore structure and microstructure， hydrophobicity， self-cleaning ability， photostability， and resistance to chloride ion penetration. The results show that calcium stearate emulsion can improve the workability of concrete and increase the surface contact angle of specimens from approximately 60° to 120°， but it inhibits the hydration reaction of cement， leading to a decrease in the compactness of concrete structure， thereby affecting the strength development at various ages. The concrete surface modified by calcium stearate exhibits good self-cleaning effects on hydrophilic dust， hydrophobic graphite powder， and oily contaminants. When the calcium stearate dosage is not higher than 1.0%， the capillary water absorption capacity and chloride ion penetration degree of concrete are significantly reduced； when the dosage is increased to 2.0%， the impermeability performance of concrete reverses due to the deterioration of pore structure， and even becomes inferior to that of the control group. After 180 d of simulated photo-aging， the contact angle decreases by less than 1°， and the hydrophobic performance remains relatively stable.

Influence of Carbon Fiber on Mechanical Properties of Polymer Modified Concrete under Impact Load

LI Mengyang, ZHANG Chao, WANG Zhihang, ZHANG Yue, SONG Xiaobo, BAI Erlei, MA Jianjun

2026, 45(8):  2664-2675.  doi:10.16552/j.cnki.issn1001-1625.2026.0170

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Polymer modified concrete （PMC） has attracted considerable attention in civil and protective engineering because of its improved toughness， crack resistance， and bonding performance compared with ordinary concrete. However， despite these advantages， PMC remains a quasi-brittle material and still exhibits limited resistance to impact and dynamic loading. To further enhance its mechanical performance and energy absorption capacity under extreme loading conditions， carbon fibers， characterized by high strength， high modulus， and excellent crack-bridging capability， were incorporated into PMC. This study aimed to systematically investigate the influence of carbon fiber content on the static and dynamic mechanical behavior of carbon fiber reinforced polymer modified concrete （CFRPMC） and to reveal its strengthening and toughening mechanisms under impact loading. Four groups of specimens containing carbon fiber volume fractions of 0%， 0.1%， 0.2%， and 0.3% were prepared. Static mechanical tests were conducted to determine compressive strength， split tensile strength， and flexural strength. Dynamic compression tests were performed using a split Hopkinson pressure bar （SHPB） system under different impact pressures. Dynamic stress-strain responses， dynamic compressive strength， peak strain， peak toughness， and failure characteristics were analyzed. Furthermore， the influence of carbon fiber content on crack propagation and fragmentation behavior was evaluated through macroscopic failure observations. The experimental results demonstrate that the mechanical performance of CFRPMC exhibits a distinct trend of initial improvement followed by deterioration with increasing carbon fiber content. Under static loading， the optimal fiber content was found to be 0.2% by volume. At this content， the compressive strength， split tensile strength， and flexural strength reach 31.72， 4.66， and 8.96 MPa， respectively， representing increases of 9.0%， 48.9%， and 43.8% compared with the fiber-free PMC. In addition， the split tensile-compressive strength ratio and flexural-compressive strength ratio increase significantly， indicating a substantial reduction in brittleness and a remarkable improvement in toughness. Under impact loading， all specimens exhibit pronounced strain-rate sensitivity. Dynamic compressive strength， dynamic peak strain， and dynamic peak toughness increase continuously with increasing strain rate. Compared with PMC， CFRPMC shows wider stress-strain plateaus around the peak stress， indicating enhanced post-cracking load-carrying capacity and improved deformation resistance. Among all mixtures， the specimen containing 0.2% carbon fiber exhibits the best dynamic performance. At comparable strain rates， its dynamic compressive strength increases by up to 23.5% relative to PMC， while its impact toughness reaches approximately 2.1 times than that of control specimen. The maximum dynamic compressive strength recorded for CFRPMC with 0.2% carbon fiber reaches 60.17 MPa at a strain rate of 133.3 s^-1.Analysis of concrete crushing morphology reveals that carbon fiber can effectively bridge microcracks and delay crack initiation and propagation during impact loading. Consequently， the failure mode gradually transforms from severe brittle pulverization to block-like fragmentation. Fragment-size observations further confirm a reduction in the proportion of fine particles after fiber incorporation， reflecting enhanced energy dissipation capability and improved structural integrity. However， excessive fiber content （0.3%） leads to fiber agglomeration， increases internal defects， and localizes stress concentrations， ultimately reducing both static and dynamic mechanical properties. Overall， the synergistic modification of polymer and carbon fiber significantly enhances the strength， toughness， and impact resistance of concrete. A carbon fiber volume fraction of 0.2% provides the optimal balance between crack-bridging efficiency and fiber dispersion， achieving simultaneous improvements in static strength， dynamic load-bearing capacity， and energy absorption performance. The findings provide valuable theoretical support and practical guidance for the design and application of high-performance impact resistance concrete materials in protective structures， transportation infrastructure， military engineering， and other critical engineering fields.

Effect of Magnetized Water on Properties and Microstructure of Concrete at Various Strength Grades

LIU Li, DING Pan, XIANG Yangsheng, HOU Li

2026, 45(8):  2676-2685.  doi:10.16552/j.cnki.issn1001-1625.2026.0201

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This study investigated the effects of magnetized water on the workability and compressive strength of concrete at four strength grades （C20， C40， C60， and C80）， using mixing water subjected to different magnetization cycles （1， 5 or 10 times） under fixed magnetic field intensity （1 T） and flow velocity （1.33 m/s）. Microstructural changes were characterized using scanning electron microscopy （SEM） and mercury intrusion porosimetry （MIP）. The results indicate that magnetized water significantly enhances concrete workability. Among the four grades， C60 concrete shows the most pronounced improvement， with slump increasing by 41.17% and flow spread by 20.27%. Regarding mechanical properties， C40 concrete exhibits the greatest gains in compressive strength， achieving increases of 16.81%， 18.37%， and 10.22% at 3， 7， and 28 d， respectively. The optimal performance is achieved at five magnetization cycles. Microstructural analysis reveals that magnetized water promotes cement hydration， leading to increased C-S-H gel formation， denser paste structure， and refined pore size distribution. These findings provide insights into the role of magnetization cycles in modulating concrete performance and support the application of magnetized water in sustainable concrete construction.

Effect of SAP on Autogenous Shrinkage and Thermodynamic Properties of Alkali-Activated Foam Concrete

LI Mingming, JIANG Dongbing

2026, 45(8):  2686-2698.  doi:10.16552/j.cnki.issn1001-1625.2026.0127

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Alkali-activated foam concrete （AAFC） possesses multiple advantages， including low density， high strength， and excellent thermal insulation. However， its inherent susceptibility to shrinkage cracking remains a critical drawback that hinders widespread practical application. This study systematically investigated the effects of the morphology and water absorption/release behavior of superabsorbent polymer （SAP） on the workability， autogenous shrinkage， compressive strength， and thermal conductivity of AAFC using ground granulated blast-furnace slag as the primary binder. The underlying mechanisms were elucidated through thermogravimetric analysis （TG）， scanning electron microscopy （SEM）， low-field ¹H nuclear magnetic resonance （¹H NMR）， and capillary pressure measurements. The results demonstrate that the addition polyacrylate SAP （SAP-A）， characterized by a high-water absorption capacity and irregular morphology， significantly increases the yield stress and plastic viscosity of the paste， markedly raises the proportion of pores larger than 500 μm in diameter， and ultimately leads to a 30.5% reduction in the 28 d compressive strength of AAFC compared to the control group without SAP. In contrast， the incorporation of acrylic acid-acrylamide copolymer SAP （SAP-M）， which exhibits a moderate water absorption capacity and spherical structure， facilitates uniform dispersion of bubbles. This optimizes the pore structure， thereby enabling the steady development of strength while reducing the thermal conductivity of AAFC to 0.089 W/（m·K）. Furthermore， SAP-M rapidly releases its absorbed water after final setting， achieving a 32.6 percentage point higher cumulative water release at 3 d compared to SAP-A. This behavior effectively alleviates the development of capillary pressure and enhances the autogenous shrinkage mitigation efficiency by 28.7%.

Verification of Integrated Mixing-Stirring-Extrusion Rapid 3D Printing Achieve Continuous Construction of Rapid-Setting Concrete

LI Weihong, DENG Yongjie, WANG Chaoying, ZHONG Jianjun, LYU Libo, MA Haiyan, YU Hongfa, LI Dongwei

2026, 45(8):  2699-2710.  doi:10.16552/j.cnki.issn1001-1625.2026.0014

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To address the conflict between the open time and setting time of rapid-setting cementitious materials caused by the “mix-then-convey process” in concrete 3D printing， as well as the consequent failure to meet the continuous construction requirements of building structures， this study adopted an independently developed integrated mixing-stirring-extrusion 3D printing device for rapid-setting concrete. With the innovative design of dual-pipeline separate delivery of dry materials and liquid， plus in-nozzle instant mixing， stirring and extrusion， this technical bottleneck was overcome. Taking rapid-setting magnesium phosphate cement （MPC） mortar as the printing material， this study systematically investigates the evolution law of the number of setting layers of printed components over time， as well as the dynamic matching relationship between the compressive strength of materials at the setting-unset interface （setting line） and the total self-weight stress of unset layers， so as to verify the feasibility of continuous construction of rapid-setting materials using this integrated process. The results show that there are always 4 to 7 unset layers above the set layers of MPC mortar printed components， and the number of unset layers gradually decreases with the progress of printing. The compressive strength of the printed layers at the setting line is always 25.6 times or more of the total self-weight stress of the unset layers， and the strength development rate was 26.7 times or more of the self-weight stress development rate of the unset layers. This indicates that the bottom set layers can continuously support the self-weight of the upper unset layers， confirming that the integrated mixing-stirring-extrusion 3D printing process enables rapid and continuous construction of MPC mortar. The research findings provide a reference for improving the 3D printing efficiency of rapid-setting cementitious materials and optimizing the printing process.

Machine Learning-Based Compressive Strength Prediction of Concrete: Model Screening and Performance Comparison

TIAN Shenhua, LI Beixing, XIAO Xiang, ZHOU Junkang

2026, 45(8):  2711-2723.  doi:10.16552/j.cnki.issn1001-1625.2026.0140

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To develop an accurate prediction model for concrete compressive strength and compare the prediction performance of different machine learning methods， this study trained 17 machine learning models using a dataset consisting of 1 030 samples， which included eight features such as water-to-binder ratio， age， and aggregate-to-binder ratio. Six models with higher accuracy were selected from these. Subsequently， each of these six models was combined with five hyperparameter optimization algorithms， namely Bayesian optimization （BO）， sparrow search algorithm （SSA）， simulated annealing （SA）， sine cosine algorithm （SCA）， and particle swarm optimization （PSO）， resulting in 30 optimized hybrid models. The models with superior accuracy were further selected for external validation and SHapley Additive exPlanations （SHAP） interpretability analysis. The results show that the least squares boosting model optimized by SSA （LSBoost-SSA）， the eXtreme Gradient Boosting model optimized by BO （XGBoost-BO）， and the light gradient boosting machine model optimized by SSA （LGBM-SSA） exhibit the best performance； XGBoost-BO achieves the optimal performance in external validation， capable of controlling the prediction error of concrete strength within 5 MPa； SHAP analysis reveals that water-binder ratio， curing age， and cement content are the core factors influencing concrete compressive strength.

Solid Waste and Eco-Materials

Research Progress on On-Site Disposal Technology of Shield Muck and Preparation of Backfill Grouting Material

LEI Zhenghui, ZHAO Chengjun, LI Yongliu, YAN Hongfu, FENG Tianyou, TAO Rencheng, JI Qiuling, GAO Zicong, MA Yuwei

2026, 45(8):  2724-2736.  doi:10.16552/j.cnki.issn1001-1625.2026.0046

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With the rapid development of urban rail transit， the efficient disposal of shield muck has become a key issue restricting the sustainable development of tunnel projects. Using shield muck to prepare backfill grouting materials can not only achieve the on-site resource utilization of muck， significantly reduce the grouting cost， but also conform to the national policy orientation of "reduction， resource utilization and harmless treatment" for construction solid waste. This paper systematically expounds the source， classification and on-site reduction treatment technology of shield muck， and focuses on summarizing the research progress and engineering application of using shield muck to prepare backfill grouting materials. The research shows that after classification treatment， the coarse particles in the muck can replace fine aggregates to provide skeleton support， and the fine particles have the potential to replace bentonite. By optimizing the curing agent system， regulating the particle size distribution and water-solid ratio， the utilization rate of muck can be effectively improved， and the fluidity， stability and compressive strength of the slurry can be improved. Engineering practice shows that the muck-based grouting materials perform well in terms of settlement control， segment floating and anti-seepage. However， they still face challenges such as large differences in muck composition， lack of standard specifications and insufficient long-term performance data. In the future， research on standardization and durability needs to be strengthened.

Research Progress on Solidification of Radioactive Waste by Phosphoric Acid-Based Geopolymers

QIN Yongbo, ZHANG Li, GUO Xiliang, WANG Ji, REN Yafeng, HAN Xu, YANG Zijie, YAN Xiaojun, GAO Chao

2026, 45(8):  2737-2748.  doi:10.16552/j.cnki.issn1001-1625.2026.0091

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Phosphoric acid-based geopolymers exhibit great application potential for radioactive waste solidification due to their excellent mechanical properties， high resistance for high temperature， and corrosion resistance. However， the immobilization mechanism of phosphoric acid-based geopolymers is complex， and related research starts relatively late， resulting in insufficiently systematic technical research and a lack of in-depth understanding of the immobilization mechanism. This paper analyzes the research progress in the field of phosphoric acid-based geopolymers for immobilizing different types of ions and wastes， and evaluates their immobilization performance by comparing the immobilization mechanisms with those of ordinary Portland cement and alkali-activated geopolymers. In addition， based on the current research progress and trends， this paper discusses the existing problems and future research directions in the application of phosphoric acid-based geopolymers for radioactive waste immobilization， providing insights for the further research and development of phosphoric acid-based geopolymer solidification technology.

A High-Fidelity Agglutinate-Containing Chang’E-5 Lunar Regolith Simulant

ZHANG Qingqing, ZHU Quanyao, XIAO Lei, MENG Zijin, SUN Huajun

2026, 45(8):  2749-2759.  doi:10.16552/j.cnki.issn1001-1625.2026.0139

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Lunar regolith is the primary object for in-situ resource utilization （ISRU）， and agglutinates， as a critical component， possess a complex microstructure that directly dictates the reliability of ISRU technologies. However， the sub-micron/nanoscale metallic iron （Fe⁰） and porous vesicular structures within agglutinates are extremely difficult to replicate under laboratory conditions， resulting in a general lack of scientific fidelity in existing lunar regolith simulants. Targeting the Chang’e-5 （CE-5） lunar regolith， this study successfully developed a high-fidelity simulant， WUT-1， through precise mineral matching and a controllable in-situ thermal reduction process， specifically overcoming the challenge of in-situ Fe⁰ precipitation within the glass matrix. Analytical results demonstrate that WUT-1 is highly consistent with the authentic lunar regolith in terms of chemical composition， phase mineralogy， and macro-physical properties， while accurately reproducing the heterogeneous microstructure. This research significantly enhances the scientific fidelity of the simulant in microstructure and fundamental physicochemical properties， providing high-reliability testing materials for the ground validation of key technologies such as lunar landing， in-situ construction， and resource extraction.

Mechanisms of Alkali-Silica Reaction Inhibition in Concrete Using Composite Solid-Waste Mineral Admixtures as Fly-Ash Replacements

XU Qing, YANG Shuqing, FENG Wei, LI Lin, CUI Hongzhi

2026, 45(8):  2760-2769.  doi:10.16552/j.cnki.issn1001-1625.2026.0120

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To address the challenges associated with the uneven regional distribution of fly ash resources and the limited availability of a stable local supply for dam construction， this study developed a composite solid-waste mineral admixture derived by solid wastes from engineering-side areas as a substitute for fly ash to mitigate alkali-silica reaction （ASR） in concrete while enabling in situ resource utilization of solid wastes. The reaction activity and mitigation effectiveness were evaluated through activity index， hydration heat， and expansion rate， while the underlying suppression mechanisms were elucidated by combining pore-solution ionic analysis with backscattered electron scanning electron microscopy. The influence on material performance was further assessed using compressive strength testing， mercury intrusion porosimetry， and thermogravimetric analysis. The results demonstrate that the composite solid-waste mineral admixture exhibits a lime consumption activity of up to 52.3%， comparable to that of fly ash. A composite solid-waste mineral admixture replacement level of not less than 20% is sufficient to control ASR expansion below the specified limit. Pore-solution ionic analysis result reveals a mitigation mechanism characterized by the reduction of alkali metal ions and the modulation of aluminum species. Thermogravimetric and porosity results indicate that， under the same mix proportion， Ca（OH）₂ is continuously consumed and the pore structure gradually densifies with curing age. Overall， this study provides a low-carbon mitigation strategy for ASR control in concrete in regions with constrained fly ash supply.

Effect of Mineral Admixtures on Hydration Kinetics of Low-Heat Portland Cement

ZHOU Junkang, LI Beixing, TIAN Jikun, TIAN Shenhua

2026, 45(8):  2770-2781.  doi:10.16552/j.cnki.issn1001-1625.2026.0226

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To reveal the influence of mineral admixtures on the hydration kinetics of low-heat Portland cement， the isothermal calorimetry was employed to measure the hydration heat evolution rate and cumulative heat of three cementitious systems with fly ash （FA）， ground granulated blast furnace slag （SL）， and their blend at mass replacement levels of 20%， 30%， and 40%， respectively. The Krstulovic-Dabic hydration kinetic model was used to quantitatively analyze the variations of kinetic parameters at different hydration stages， and the results were verified by mechanical property tests. The results show that the incorporation of mineral admixtures reduces the hydration heat and strength of low-heat Portland cement. The fitting results of the Krstulovic-Dabic model indicate that FA and SL exhibit different effects on the hydration kinetics. Specifically， the rate constant K_{\mathrm{3}}^{\mathrm{\text{'}}} in the diffusion-controlled stage decreases with increasing dosage when FA is added alone or when FA and SL are blended， but increases with increasing dosage when SL is added alone. Under a constant total dosage of mineral admixtures， the hydration rate constants and the degree of hydration at the transition points of the FA-SL blended system are intermediate between those of the single FA system and the single SL system， demonstrating a synergistic effect between the two admixtures in low-heat Portland cement. Mechanical property tests macroscopically verify the synergistic optimization effect of FA and SL blending on strength development. Considering both strength development and hydration temperature rise control， the combined use of FA and SL is a balanced strategy to optimize the performance of low-heat Portland cement.

Performance and Comprehensive Benefit of Eco-Friendly Ultra-High Performance Concrete with Molybdenum Tailings

FENG Junjie, LI Yixiao, MA Yan, GENG Shenghan, SHEN Xingyue, YAN Shaoyang, WANG Xinwu, LIU Qi

2026, 45(8):  2782-2793.  doi:10.16552/j.cnki.issn1001-1625.2026.0154

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To address the prominent issues of high carbon emissions and high energy consumption in the production of ultra-high performance concrete （UHPC）， this study proposed a synergistic utilization strategy for molybdenum tailings powder and sand， aiming to realize the high-value utilization of all components of molybdenum tailings. The mix proportion of UHPC was optimized based on the particle closest packing theory and wet packing density method. Eco-friendly UHPC was prepared by substituting cementitious materials with mechanically activated molybdenum tailings powder and quartz sand with molybdenum tailings sand， and the performance and comprehensive benefit of UHPC were studied. The results indicate that UHPC exhibits favorable workability， high compressive strength and a dense pore structure when the replacement rate of molybdenum tailings powder is no more than 30% （mass fraction） or that of molybdenum tailings sand is no more than 75% （mass fraction）. The eco-friendly UHPC prepared with 20% （mass fraction） molybdenum tailings powder and 75% （mass fraction） molybdenum tailings sand exhibits a slump flow of 585 mm， meeting the workability requirements for construction. Its compressive strength reaches 154.8 MPa， an increase of 3.1% compared with that of the reference group （without molybdenum tailings）. The resource utilization rate of molybdenum tailings attains 48.8%， and the carbon emissions， energy consumption and material costs per unit strength per unit volume are reduced by 17.5%， 14.9% and 30.6% respectively relative to the reference group. This study provides references for the low-carbon preparation of UHPC and the high-value conversion of molybdenum tailings.

Macroscopic Properties and Microstructure Analysis of Mixed Ceramic-Fiber-Rubber Composite Mortar

XU Guang, DU Xiangqin, WU Tingjie, ZHU Yuanshuai, WANG Chunyi, LIU Xingjie

2026, 45(8):  2794-2805.  doi:10.16552/j.cnki.issn1001-1625.2026.0178

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To alleviate the increasing scarcity of sand resources and overcome the inherent brittleness of mortar， this study utilized ceramic sand and rubber particles as partial replacements of mechanism sand by mass and added polypropylene fibers to design and fabricate 9 groups of composite mortar specimens with different mix ratios. Through flowability tests， mechanical property tests， as well as scanning electron microscopy， energy dispersive spectrometer and mercury intrusion porosimetry tests， the effects of ceramic sand， PPF and rubber particles on the workability， mechanical properties and microstructure of mortar were investigated. The results show that when ceramic sand replaces 50% （mass fraction） of mechanism sand， it doesn’t adversely affect the fluidity， and the 28 d compressive strength is improved. The co-addition of PPF and rubber particles reduces the flowability， compressive strength， splitting tensile strength， and flexural strength of mortar， but improves the toughness of the composite mortar specimens. The interface between ceramic sand and mortar is dense and compact. When the replacement rate of ceramic sand is 50%， the porosity， average pore diameter and pore area of the mortar all decrease. The inclusion of PPF and rubber particles weakens the interface transition zone of mortar. Furthermore， PPF increases the average pore diameter and porosity of mortar， while rubber particles refine the pore diameter and improve the pore size distribution， but increase the number of harmful pores.

Performance Enhancement of Excess-Sulfate Phosphogypsum-Slag Cement Through Electrochemically Activated Red Mud

TANG Pei, ZHU Meiyi, RONG Pengjie, CHEN Wei

2026, 45(8):  2806-2816.  doi:10.16552/j.cnki.issn1001-1625.2026.0130

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Excess-sulfate phosphogypsum-slag cement （ESPSC） represents a low-carbon cementitious material that simultaneously valorizes phosphogypsum and granulated blast furnace slag （GGBS）， with carbon emissions only 20% to 30% of ordinary Portland cement. However， residual soluble phosphorus and fluorine impurities in phosphogypsum severely retard hydration， resulting in critically low early-age strength that limits practical application. Red mud， a strongly alkaline byproduct of Bayer-process alumina refining with global stockpiles exceeding 4 billion tonnes， theoretically provides reactive aluminum to promote hydration， yet its active components are predominantly locked within stable crystalline minerals including cancrinite， muscovite， and kaolinite. Traditional activation routes such as thermal calcination and mechanical grinding are energy-intensive and incompatible with low-temperature ESPSC system， necessitating a greener activation approach.

This study employed an electrochemical method to activate red mud at a constant potential of 1.15 V versus Hg/HgO in 4 mol/L NaOH solution at 60 ℃ for 3 h， exploiting cathodic reduction of iron oxides to disrupt the mineral lattice and liberate reactive aluminum species. The electrochemically activated red mud was incorporated into ESPSC at replacement levels of 10%， 15%， and 20% by mass， and its effects on mechanical properties， hydration products， microstructure， and hydration kinetics were systematically characterized using XRD， TG-DTG， SEM-EDS， ICP-MS， and isothermal calorimetry. Electrochemical treatment induces partial transformation of crystalline minerals to amorphous phases， evidenced by the weakening or disappearance of cancrinite and muscovite diffraction peaks. Ion dissolution analysis shows that aluminum concentration in the filtrate increases 18.6-fold to 259.521 mg/L， iron concentration decreases by 95.4% to 0.030 mg/L， and solution pH rises from 10.64 to 12.48， confirming substantially enhanced pozzolanic reactivity.

Incorporation of 20% electrochemically activated red mud achieves a 3 d compressive strength of 24.1 MPa， a 6.3-fold improvement over the reference group， and a 28 d strength of 45.8 MPa， a 40.5% increase. TG-DTG analysis shows that the mass loss ratio in 60 to 120 ℃ range rises from 3.32% to 7.61% at 3 d， confirming markedly greater ettringite and C-（A）-S-H gel formation. Isothermal calorimetry reveals that the hydration induction period is shortened from approximately 40 h to as little as 3 h. SEM-EDS observations confirm a denser microstructure with uniformly distributed ettringite and abundant C-（A）-S-H gel filling the pore space， while high Al and Si atomic fraction of 9.25% and 7.84% （paste with 20% electrochemically activated red mud） in partially reacted red mud particles， which verifies that reactive aluminum participates in hydration. The enhancement is attributed to two synergistic mechanisms： the greatly increased reactive aluminum supply accelerates early ettringite formation， and the retained alkalinity further activates slag by promoting Si—O and Al—O bond breakage to sustain C-（A）-S-H gel growth at later ages. This work provides an effective technical pathway for red mud valorization and addresses the inherent early-strength deficiency of ESPSC systems.

Preparation and Properties of Core-Shell Structured Solid Waste-Based Non-Sintered Ceramsite

ZHU Sen’ao, HUANG Xiulin, PENG Li, CAO Panpan

2026, 45(8):  2817-2828.  doi:10.16552/j.cnki.issn1001-1625.2026.0244

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To realize the high-value and large-scale utilization of industrial solid wastes and address the high energy consumption and high carbon emission problems of traditional sintered ceramsite， this study integrates core-shell structure design with interface modification strategy. Using stone tailing powder （STP） and flue gas desulfurization gypsum （FGDG） as the main raw materials， this work prepares high-volume solid waste-based non-sintered ceramsite. The dual bonding interface strengthening mechanism anchored by Si—O—Si covalent bonds and bridged by carboxyl—Ca^2＋ coordination bonds of the modifier was revealed. The shell proportioning and modifier synthesis process were optimized via orthogonal tests. The effects of modifier dosage， water-to-material ratio and curing age on the properties of ceramsite were systematically investigated， and XRD， SEM， and FT-IR were adopted for microscopic characterization. The results show that under the optimal formulation， the mass ratio of flue gas desulfurization gypsum to mineral powder is 1∶2， the mass fraction of stone tailing powder is 60%， the cement content is 8%， the modifier dosage is 2.0%， the water-to-material ratio is 0.24， and the curing age is 28 d. The prepared ceramsite achieves a cylinder compressive strength of 4.8 MPa， a bulk density of 751.2 kg/m³， and the 1 h water absorption is reduced to 7.1%， which complies with “Lightweight aggregates and their test methods—part 1： Lightweight aggregates” （GB/T 17431.1—2010）. The ceramsite exhibits excellent application performance in thermal insulation partition boards and lightweight concrete， providing theoretical support and a feasible technical route for the preparation of high-performance lightweight aggregates from industrial solid wastes.

Thermally Activated Coal Gangue and Its Application in Phosphogypsum Slag Cement

TANG Pei, LIU Jiaxin, QU Bo, RONG Pengjie, CHEN Wei

2026, 45(8):  2829-2838.  doi:10.16552/j.cnki.issn1001-1625.2026.0086

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To address the dual challenges of large-scale phosphogypsum disposal and mineral powder shortage in phosphogypsum slag cement， this study systematically investigated the feasibility of thermally activated coal gangue as a substitute for mineral powder and its influence mechanism on cement performance， while promoting the resource utilization of industrial solid waste. Coal gangue was calcined at 600 ℃ to 800 ℃ for activation and was used to replace mineral powder at various mass fractions （10% to 100%）. The mechanical properties， hydration process， and microstructural evolution of the materials were comprehensively evaluated. The results demonstrate that at early age （7 d）， coal gangue activated at 700 ℃ exhibits optimal enhancement at a 20% replacement rate， with compressive strength increasing by 12.38% compared to the control group. At later age （28 d）， coal gangue activated at 600 ℃ demonstrates superior mechanical performance at a 20% replacement rate， achieving a compressive strength increase of 53.62%. Phase analysis reveals that thermal activation transforms kaolinite in coal gangue into metakaolinite， significantly enhancing the leaching rate of reactive silica and alumina and thereby promoting pozzolanic reactivity， which facilitates increased formation of ettringite （AFt） and C-（A）-S-H gel. Hydration heat analysis confirms that thermally activated materials accelerate the early-stage hydration process and shorten the induction period. This study demonstrates that thermally activated coal gangue can serve as an effective substitute for mineral powder in phosphogypsum slag cement systems， providing crucial technical support for the high-value utilization of bulk solid waste and the development of low-carbon cementitious materials.

Influence Mechanism of Additives on Mildew of Phosphogypsum

CHENG Xiao, WU Fade, WANG Hongxia, SONG Xiaoguang, GAO Chunyong, GUO Junhua, LI Fan

2026, 45(8):  2839-2849.  doi:10.16552/j.cnki.issn1001-1625.2026.0180

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Mildew on phosphogypsum products not only poses a threat to human health but also causes significant deterioration of material properties. This study was investigated the influence mechanism of additive types and dosages on the mildew of phosphogypsum， based on commonly using additives in the production of phosphogypsum products. The samples were characterized using XRF， EA， SEM， and static contact angle measurements to preliminarily explore the mildew mechanism of phosphogypsum. The results indicate that a higher dosage of water reducer accelerates the mildew rate of phosphogypsum. At the same dosage， naphthalene-based water reducer is more likely to induce mildew on phosphogypsum compared to polycarboxylate-based water reducer. A higher dosage of waterproofing agent slightly reduces the mildew rate， suggesting that waterproofing agent can improve mildew resistance to a certain extent. Increasing the surface environmental pH of phosphogypsum promotes the growth of the six selected fungal strains， making the material more susceptible to mildew. The carbon （C） element introduced by additives is the primary factor accelerating mildew， followed by nitrogen （N）. Elements such as K， Mg， Al， and P， which are macronutrients required for microbial growth， have a certain influence on mildew， but their effects are relatively minor.

Ceramics

Research Progress on Toughening Technologies of Silicon Nitride Ceramics

NIE Jingkai, HOU Dong, ZOU Jianming, CHEN Tian, ZHANG Yiming, HAN Yu, HE Qiang

2026, 45(8):  2850-2862.  doi:10.16552/j.cnki.issn1001-1625.2026.0172

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As a high-performance structural engineering ceramics， Si₃N₄ has emerged as an ideal candidate material for demanding applications in advanced sectors such as aerospace， automotive， electronics， and medical technology， owing to its outstanding mechanical properties， wear resistance， thermal shock resistance， and chemical stability. However， the inherent high brittleness of Si₃N₄-based ceramics greatly restricts their application in a wider range of engineering fields. Over the years， researchers worldwide have conducted extensive research on the insufficient toughness in Si₃N₄-based ceramics. This paper systematically reviews the research progress on improving the toughness of Si₃N₄ ceramics： firstly， starting from the key factors affecting fracture toughness， it elaborates on the influence of powder properties of raw materials， sintering aid system， sintering process， and grain morphology and orientation distribution on the toughness of Si₃N₄ ceramics； based on this， it conducts in-depth analysis and discussion of the main toughening strategies and mechanisms. Finally， the paper outlines the future development trends and key breakthrough directions for high-toughness Si₃N₄ ceramics.

Multiscale Damage Analysis and Experimental Study of Crack Propagation in SiC

FENG Boping, YU Puliang, MU Zelong, LIU Yuanjiong, DING Xin, WU Jiulin

2026, 45(8):  2863-2875.  doi:10.16552/j.cnki.issn1001-1625.2026.0157

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Silicon carbide （SiC） is a high-performance ceramic material with high strength， high-temperature resistance， high thermal conductivity， and excellent chemical stability. These properties make it widely used in aerospace thermal protection， nuclear structural components， and semiconductor manufacturing. However， micro-defects and mesoscale pores are inevitably introduced during fabrication， severely limiting processing efficiency and service reliability. It is therefore of considerable engineering importance to develop a reliable multiscale damage analysis method capable of bridging microscopic damage mechanisms and macroscopic fracture behavior. To this end， this study proposed a multiscale damage analysis method that integrates molecular dynamics （MD） and the cohesive zone model. The method quantitatively investigated the effects of different micro-defect configurations and porosity levels on the fracture toughness of polycrystalline SiC.

At the microscale， MD simulations were conducted using an improved Tersoff potential for β-SiC， and traction-separation （T-S） curves were obtained under both intergranular and transgranular fracture modes. The critical traction ranged from 27.77 GPa to 30.91 GPa for intergranular fracture and from 39.01 GPa to 41.86 GPa for transgranular fracture. Among the five micro-defect types， the rectangular crack consistently yielded the highest critical traction. Introducing a void along the path of a propagating rectangular crack reduced the critical traction， whereas increasing the aspect ratio of an elliptical void effectively enhanced it. Cohesive parameters， specifically maximum tensile stress， stiffness coefficient， and fracture energy， were subsequently extracted from the T-S curves via bilinear fitting and served as input for the mesoscale and macroscale models. At the mesoscale， polycrystalline models with different porosities were constructed using a bilinear boundary Voronoi diagram method. To realistically represent the porosity， circular pores with a diameter of 20 μm were uniformly embedded. The extracted cohesive parameters were assigned to zero-thickness cohesive elements inserted along grain boundaries and within grains， thereby predefining potential crack propagation paths. Based on the mesoscale models， a 2D plane-strain three-point bending finite element model was established， featuring a length of 20 mm， a width of 4 mm， and a pre-crack length of 2 mm. The simulation results indicated that， at a given porosity， the rectangular crack yielded the highest critical reaction force and fracture toughness， while the combination of the prolate elliptical void and the rectangular crack yielded the lowest. This finding was consistent with the MD results. For identical micro-defects， fracture toughness was negatively correlated with porosity. Compared with the pore-free model， the average fracture toughness decreased by 2.89% for 3% porosity and by 7.33% for 6% porosity. The predicted critical stress intensity factor ranged from 1.87 MPa·m^1/2 to 1.98 MPa·m^1/2 at 0% porosity， from 1.82 MPa·m^1/2 to 1.92 MPa·m^1/2 at 3% porosity， and from 1.73 MPa·m^1/2 to 1.87 MPa·m^1/2 at 6% porosity. Finally， three-point bending tests were performed on SiC specimens with 3% porosity. The experimental results show an average critical reaction force of 10.60 N and an average fracture toughness of 1.93 MPa·m^1/2. The maximum deviation between the experimental and simulated fracture toughness was 8.63%， confirming the accuracy of the proposed method.

Overall， the proposed method provides an effective tool for fracture assessment and reliability-oriented design of SiC and related ceramic components. In particular， it offers guidance for optimizing porosity and micro-defect configuration during processing， and enables evaluation of the influence of these factors on structural fracture toughness at the material design stage， thereby helping reduce the risk of catastrophic fracture failure. Future work will incorporate more realistic pore morphologies， processing-induced heterogeneity， and multiphase effects to further extend the applicability of the method to more complex ceramic materials.

Fe₃O₄/CeO₂ Photocatalytic Fenton Reaction-Based Chemical Mechanical Polishing Slurry for Silicon Carbide Wafers and Its Mechanism

LI Wangyang, LYU Gong, WANG Kaiyue

2026, 45(8):  2876-2881.  doi:10.16552/j.cnki.issn1001-1625.2026.0173

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Silicon carbide （SiC） wafers， owing to their excellent physicochemical properties， are widely used in aerospace， 5G communications， and other fields. Chemical mechanical polishing （CMP） is an important method for achieving an ultra-smooth surface on SiC wafers. However， conventional polishing slurries still have drawbacks such as complex synthesis processes and high application costs. To address these issues， this study developed a Fe₃O₄/CeO₂ photocatalytic Fenton reaction system and an efficient CMP process suitable for the C-face of SiC wafers. SEM and AFM characterization results show that， after treatment with the photocatalytic polishing slurry， the surface quality of SiC is significantly improved， yielding an ultra-smooth surface. XPS valence-state analysis reveals that the electron transfer cycle formed between Fe³⁺/Fe²⁺ on the catalyst surface effectively promotes the continuous generation of hydroxyl radicals， thereby enhancing the oxidation of the SiC surface. Optimization results show that the material removal rate of the photocatalytic polishing slurry reaches 1 068 nm/h， while the surface roughness after polishing is reduced to 0.2 nm. These findings provide a new approach to the efficient， green， and ultra-precision machining of SiC materials.

Room-Temperature Flash Sintering of Lanthanum Chromate Through Co-Doping

GUAN Lili, WU Li, SI Zhipeng, BIAN Ziheng

2026, 45(8):  2882-2889.  doi:10.16552/j.cnki.issn1001-1625.2026.0107

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Doped lanthanum chromite ceramics possess high electrical conductivity and excellent high-temperature stability， demonstrating broad application prospects. However， lanthanum chromite materials are difficult to densify. In order to lower their sintering temperature and simplify the fabrication process， this paper applied the flash sintering technique to the preparation of this type of material. The effects of Co ion single doping and A/B-site Ca-Co ions co-doping on the structure， intrinsic properties， and flash sintering behavior of lanthanum chromite were investigated. The results indicate that， compared with LaCr_0.8Co_0.2O₃， further doping with Ca²⁺ induces oxygen vacancies and optimizes the charge carrier characteristics. The rapid migration driven by the electric field reduces the threshold value conditions required for the onset of flash sintering， thereby ultimately enabling the rapid sintering of La_0.9Ca_0.1Cr_0.8Co_0.2O₃ ceramics under a low electric field at room temperature. A fully dense structure is achieved after flash sintering for 60 s. Additionally， the fabrication efficiency is substantially improved compared to conventional high-temperature sintering at 1 650 ℃. This study elucidates the modulating effect of doping on the flash sintering behavior at low temperature of lanthanum chromite， offering a feasible pathway for the room-temperature sintering of functional ceramics of this type. It also provides experimental evidence and a theoretical reference for the application of direct-current flash sintering technology in the energy-efficient preparation of ceramic materials.

Effect of Yb₂O₃ Co-Doping on Properties of Lu₂O₃∶Eu Transparent Ceramics

CHEN Jian, JING Wei, WANG Yaozhi, KONG Zhipeng, WU Hao

2026, 45(8):  2890-2898.  doi:10.16552/j.cnki.issn1001-1625.2026.0055

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Europium-doped lutetium oxide （Lu₂O₃∶Eu） transparent ceramics exhibit high density （9.4 g/cm³） and strong stopping power for MeV-level X-rays， making them highly promising for applications such as industrial non-destructive testing. However， the relatively large ionic radius of Eu³⁺ tends to induce grain boundary segregation and residual porosity， leading to scattering losses. Meanwhile， the presence of deep-level traps in the Lu₂O₃ matrix results in significant afterglow， limiting their application in high-frequency imaging. In this study， Yb₂O₃ was introduced as a dual-functional sintering aid and energy-level regulator， and （Lu_0.95-xYb?Eu_0.05）₂O₃ （x=0， 0.01， 0.03， 0.05， 0.10） transparent ceramics were fabricated via vacuum sintering combined with hot isostatic pressing. The results show that when the Yb³⁺ content is 10%（atomic percentage）， the in-line transmittance of the sample at 611 nm increases from 60% to 74%. Spectroscopic analysis confirms a cooperative energy transfer process from Eu³⁺ to Yb³⁺. Although this process induces partial luminescence quenching， it introduces new non-radiative relaxation channels that compete with trap capture， reducing the afterglow intensity by nearly two orders of magnitude and significantly suppressing the afterglow.

Fabrication and Properties of Mg_0.75Al_2.16O₄ Transparent Ceramics by SPS Combined with Hot Isostatic Pressing

WU Wentao, TU Guangsheng, LIAO Jiaxing, ZHANG Chaojie, TU Bingtian, WANG Hao

2026, 45(8):  2899-2908.  doi:10.16552/j.cnki.issn1001-1625.2026.0137

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Aluminum-rich spinel transparent ceramics exhibit excellent mechanical and optical properties and have significant application potential in optoelectronic windows and transparent armor. In this study， transparent ceramics were prepared from single-phase Mg_0.75Al_2.16O₄ powders by spark plasma sintering combined with hot isostatic pressing （HIP） treatment. The phase composition and microstructural evolution of the ceramics during pressure-assisted sintering were systematically investigated. The results show that a significant amount of α-Al₂O₃ secondary phase precipitates in samples at 1 300 ℃. With increasing SPS pre-sintering temperature， the content of the α-Al₂O₃ phase gradually decreases and completely disappears at 1 500 ℃. Pre-sintered ceramics with fine grains and low porosity are obtained at 1 400 ℃. After HIP treatment， the transparent ceramics exhibit an average grain size of approximately 2.88 μm， and the in-line transmittance in the visible and infrared regions reaches 72% （500 nm） and 84% （2 500 nm）， respectively. Benefiting from the formation of a fine-grained microstructure， the Vickers hardness of the samples reaches 14.3 GPa， which is about 10% higher than that of conventional MgAl₂O₄ transparent ceramics. This study provides insight into the fabrication and performance modulation of aluminum-rich spinel transparent ceramics with refined microstructures.

Glass

Effects of Pre-Irradiation Methods on Radiation Resistance of Silica Glass

WEI Lai, WU Junhao, ZHANG Xiaotong, CHEN Congyi, GAO Zitao, LING Xue, JIN Ke, GUO Xun, WANG Guobiao, CUI Yinan

2026, 45(8):  2909-2918.  doi:10.16552/j.cnki.issn1001-1625.2026.0138

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Silica glass and optical fibers are widely utilized in critical applications such as nuclear industry monitoring systems and remote sensing satellites due to their exceptional optical properties and robust radiation resistance. However， exposure to intense radiation can induce the formation of color center defects within the quartz glass matrix， which severely compromises its optical performance. Strategies to enhance the radiation resistance of glass materials are broadly categorized into pre-treatments and post-treatments. Pre-treatments improve material properties directly or indirectly via doping， gas loading and other techniques. Post-treatment approaches utilize photo-bleaching or thermal bleaching to facilitate the transformation or annihilation of radiation-induced color center defects， with thermal bleaching being extensively adopted due to its procedural simplicity and broad applicability. The pre-irradiation method employs a combination of initial irradiation and subsequent thermal annealing to eliminate the detrimental effects of precursor defects， thereby enhancing overall radiation resistance. Despite its potential， the optimal temperature ranges and annealing parameters require further clarification， and there is a noticeable lack of systematic comparative studies concerning defect evolution mechanisms under various annealing conditions. Based on pre-irradiation experiments， this study systematically investigates the formation dynamics of γ-irradiation-induced color center defects and the underlying mechanisms by which different high-temperature annealing behaviors influence radiation resistance.γ-irradiation experiments were conducted on a 1.25 MeV ??Co source platform at the China institute of atomic energy. The irradiation dose rate was maintained at 2 kGy/h， with total doses established at 1， 10， and 100 kGy. A systematic series of annealing treatments was subsequently conducted： room-temperature dark annealing for durations of 1， 3， and 6 months； high-temperature annealing in both air and hydrogen atmospheres at 400， 600， 800， and 1 000 ℃； and variable-duration isothermal annealing at 800 ℃ in an air atmosphere for 10， 20， 30， and 40 min. The annealed samples were then subjected to secondary irradiation at 2 kGy/h up to a total dose of 100 kGy. Changes in optical transmittance， alongside the types and concentrations of structural defects， were characterized using ultraviolet-visible （UV-Vis） spectrophotometry and electron paramagnetic resonance （EPR） spectroscopy.The experimental results demonstrate that γ-irradiation predominantly induces the generation of E’ center defects （g₁=2.004 4， g₂=2.003 5， g₃=2.003 1）， along with a minor presence of non-bridging oxygen hole centers （NBOHC）. When the total irradiation dose reached 100 kGy， the sample exhibited a maximum transmittance degradation of 23.5% （primarily located in the ultraviolet band）， while the E’ center concentration escalated to 2.228×10¹⁶ spins/g. Room-temperature annealing over a period of 6 months resulted in a marginal transmittance recovery of only 5.1%， primarily attributed to the gradual annihilation of NBOHC defects. In contrast， high-temperature annealing yielded significant restorative effects. The optimal treatment was identified as annealing at 800 ℃ in an air atmosphere， which improved the sample’s transmittance by 21.23% relative to its post-irradiation state. Crucially， following secondary irradiation， the transmittance of the samples annealed in air at 800 ℃ was 7.5% higher than their transmittance after the primary irradiation. Conversely， although annealing in a hydrogen atmosphere could successfully reduce defect concentrations in the short term， the newly formed Si-H bonds proved highly unstable and easily fractured during secondary irradiation， ultimately exacerbating the overall radiation damage.From the dual perspectives of optical performance and microstructural defect evolution， this paper systematically elucidates the mechanisms through which pre-irradiation methods under varying conditions impact the radiation resistance of quartz glass. These findings provide experimental foundation and theoretical reference for extending the operational service life of optical glass and fiber materials deployed in severe radiation environments.

Functional Materials

Progress in Synthesis and Applications of Vaterite-Type Calcium Carbonate

ZHAO Zeqian, LI Yutong, LI Jiangong, ZHANG Xiaosheng, LI Xiangyuan, BAO Weiren, DU Zhenyi, QIN Zhifeng

2026, 45(8):  2919-2931.  doi:10.16552/j.cnki.issn1001-1625.2026.0118

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Vaterite-type calcium carbonate is a metastable crystal form of calcium carbonate. Due to its high specific surface area， good dispersibility， easy conversion and easy functionalization， it has application potential in the fields of functional fillers， biomedicine and environmental governance. However， vaterite is easily converted to calcite/aragonite， which limits its controllable preparation and large-scale application. In this paper， the synthesis strategy and crystal regulation mechanism of vaterite are systematically summarized. The typical routes such as double decomposition method， carbonization method and gel/microemulsion method are mainly summarized. The effects of temperature， pH value and additives on nucleation-growth kinetics， particle size/morphology and crystal form proportion are summarized. Based on the structure-property relationship， the application performance and engineering challenges of vaterite in the fields of functional fillers and coatings， lubrication and rubber/latex materials， water purification and solid waste mineralization and drug delivery are summarized. Finally， the crystal form regulation framework with supersaturation window-mesophase path-interface adsorption selectivity as the core is proposed， and the large-scale preparation， stabilization regulation and green high-value application research are prospected， which provides a reference for the development and application of vaterite materials.

Preparation and Electrochemical Performance of B, N Co-Doped Carbon/Ti₃C₂T_xComposites

MA Sasa, CHEN Yongjun, HE Zihan, WANG Qianyi, WANG Zichen, LI Jianbao, LUO Lijie

2026, 45(8):  2932-2943.  doi:10.16552/j.cnki.issn1001-1625.2026.0126

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With the escalating demand for reliable grid-scale energy storage systems， aqueous zinc-ion capacitors （ZICs） have garnered extensive research attention owing to their intrinsic safety， cost-effectiveness， and their ability to bridge the performance gap between high-energy batteries and high-power supercapacitors. Among myriads of electrode materials， two-dimensional （2D） layered Ti₃C₂T_xmaterials have emerged as highly promising candidates due to their metallic conductivity， excellent hydrophilicity， and tunable surface chemistry. However， the severe self-restacking of nanosheets， driven by strong van der Waals forces， remains the critical bottleneck restricting their practical application. This phenomenon drastically reduces the accessible electrochemically active surface area and severely hinders internal ion transport kinetics. To address this inherent challenge， this work rationally designed a novel composite electrode by integrating chlorella-derived boron and nitrogen （B， N） co-doped carbon with Ti₃C₂T_xnanosheets， aiming to enhance energy storage performance through synergistic effects.

In this work， a cost-effective and eco-friendly preparation process was developed using Chlorella microalgae and boric acid as precursors. Initially， B， N co-doped carbon （CC） was synthesized via a hydrothermal pretreatment， followed by high-temperature carbonization and potassium hydroxide （KOH） activation. Subsequently， the obtained CC was assembled via electrostatic self-assembly with etched Ti₃C₂T_xnanosheets to fabricate a series of CC/Ti₃C₂T_xcomposites （CTxy） with varying mass ratios. Comprehensive microstructural characterization indicate that the appropriate introduction of carbon materials effectively inhibits the self-restacking of Ti₃C₂T_xlayers， expands the interlayer spacing， and constructs a robust multidimensional interconnected architecture. Particularly， the composite with the optimal proportion， CT11 （with a CC to MXene mass ratio of 1∶1）， exhibits a significantly increased specific surface area of 626.54 m² g^-1， while concurrently forming a hierarchical porous network that provides abundant ion transport channels and high-density electrochemically active sites.

Electrochemical measurements reveal that the composite electrode exhibits outstanding performance in a three-electrode testing system： at a current density of 0.1 A g^-1， the specific capacity of the CT11 electrode reaches 243.53 mAh g^-1. Upon assembling CT11 with a zinc anode into a full aqueous zinc-ion capacitor， the device demonstrates immense potential for practical application. At a current density of 0.1 A g^-1， the device delivers a high reversible specific capacity of 166.5 mAh g^-1； even at an ultra-high current density of 20 A g^-1， it maintains an excellent rate capability of 81.1 mAh g^-1. Crucially， the CT11//Zn zinc-ion capacitor exhibits ultralong cycling stability， retaining 85.71% of its initial capacity after 16 000 continuous charge-discharge cycles at a high current density of 10 A g^-1， demonstrating its superior electrochemical reversibility. In summary， the superior electrochemical performance of the composite originates from the synergistic interaction between Ti₃C₂T_xand the B， N co-doped carbon. This highly efficient structural modulation strategy not only optimizes the ion and electron transport pathways but also enhances the interfacial pseudocapacitive storage mechanisms. This work proposes a facile， sustainable， and practical structural modification strategy for MXene-based composites， providing broad insights for the precise design of next-generation high-performance aqueous zinc-ion capacitors.

Road Materials

Experimental Study on Permeability and Runoff Purification Performance of Microbial Enhanced Recycled Pervious Concrete

CHEN Minli, QIN Xiao, XIN Xiangyu, ZHANG Haolin, LIN Yongkang

2026, 45(8):  2944-2955.  doi:10.16552/j.cnki.issn1001-1625.2026.0165

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Using microbial-induced carbonate precipitation （MICP） technology to repair recycled aggregate for pervious concrete pavement can effectively avoid aggregate damage and environmental pollution caused by physical or chemical repair. In this paper， the influences of recycled aggregate content and design porosity on the permeability and pore characteristics of recycled pervious concrete were studied. Through the dynamic adsorption test of runoff pollutants， the periodic evolution characteristics of the purification efficiency of pervious concrete on heavy metal pollutants in runoff before and after aggregate repair were deeply explored. With the help of scanning electron microscopy combined with energy dispersive spectroscopy （SEM-EDS）， the distribution characteristics and relative content of residual elements on the surface of concrete pore wall were further analyzed， and the purification mechanism was revealed from the micro level， so as to realize effective engineering application. The results show that with the increase of recycled aggregate content， the permeability coefficient and connected porosity difference between concrete after strengthening and before strengthening increases. When the content is 50% （volume fraction）， the permeability coefficient and the connected porosity are reduced by 31.51% and 15.15% respectively compared with those before strengthening， which is attributed to the filling effect of biological CaCO₃ on aggregate defects. The initial purification rate of Zn²⁺， Cr³⁺ and Pb²⁺ by pervious concrete is increased to 35% to 80% by biological CaCO₃， and the adsorption effect of Zn²⁺ is the best， followed by Cr³⁺ and Pb²⁺. The biological CaCO₃ on the aggregate surface can undergo ion exchange and surface chemical complexation with heavy metal ions in the runoff， significantly increasing the residual amount of heavy metal elements on the surface of the concrete pore wall， and showing local enrichment characteristics， with excellent purification efficiency.

Road Performance of Base with Phosphogypsum Replacing Coarse/Fine Aggregates

ZONG Wei, LIU Cheng, ZHENG Wuxi, ZHANG Qixin, DONG Xianzheng

2026, 45(8):  2956-2966.  doi:10.16552/j.cnki.issn1001-1625.2026.0247

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To explore the resource utilization of phosphogypsum in road base materials， this study conducted basic mechanical tests， freeze-thaw and dry-wet cycle tests， dry shrinkage tests， expansion tests and pollutant leaching tests. A comparative study was performed on the road performance of two base layers： phosphogypsum composite stabilized crushed stone base （phosphogypsum powder replacing fine aggregate） and phosphogypsum artificial aggregate base （phosphogypsum artificial aggregate replacing coarse aggregate）. The results show that both materials meet the mechanical requirements for road application. Due to the low cylinder compressive strength， high crushing value and high soft stone content of artificial aggregate， the 360 d unconfined compressive strength of phosphogypsum artificial aggregate base is 6.12 MPa lower than that of the phosphogypsum composite stabilized crushed stone base. The two materials have comparable frost resistance and water stability， but present significant differences in dry shrinkage behavior. The phosphogypsum composite stabilized crushed stone base exhibits slight expansion with a 60 d dry shrinkage coefficient of -0.13×10^-6 με/%， while the phosphogypsum artificial aggregate base suffers severe dry shrinkage with a coefficient of 195.42×10^-6 με/% and more obvious performance degradation under dry-wet alternating conditions.In terms of volume stability， the phosphogypsum artificial aggregate base barely expands with a cumulative expansion rate of only 0.03%， while the phosphogypsum composite stabilized crushed stone base reaches 0.35% owing to ettringite formation. The property differences are mainly attributed to the various content of ettringite， C-S-H gel and structural compactness. Furthermore， the leaching concentrations of total phosphorus and fluoride of the two materials fully comply with the current class Ⅲ standard for surface water.