Table of Content

Volume 45 Issue 5
15 May 2026

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Cement and Concrete

Effect of Temperature Rising Inhibitor on Hydration of Ferroaluminate Cement

ZHU Jiajun, LIAO Yishun, GUO Junping, LI Wenhua, LI Lingyun

2026, 45(5):  1483-1490.  doi:10.16552/j.cnki.issn1001-1625.2025.1070

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In order to solve the problems of concentrated heat release and rapid setting of ferroaluminate cement-based materials， the influence of temperature rising inhibitor on the hydration process and physical-mechanical properties of ferroaluminate cement was investigated through tests of fluidity， setting time， compressive strength， hydration heat and hydration products analysis. The results show that the addition of temperature rising inhibitor improves the fluidity of cement mortar and prolongs the setting time of cement paste. When the content of temperature rising inhibitor is 2.0%（mass fraction）， the initial and final setting time of cement paste are 73 and 106 min respectively， which are 49 and 68 min longer than those of the sample without inhibitor. When temperature rising inhibitor is added， the compressive strength of the specimen decreases obviously at the early age of 6 h. Compared with the sample without inhibitor， the compressive strength decreases by 38.14% when the content of the inhibitor is 2.0%， and then the effect of the inhibitor gradually weakens with increasing age， and hydration gradually recovers. At the same time， the addition of inhibitor delays the time of the exothermic peak of cement hydration. When the content of inhibitor is 2.0%， compared with the sample without inhibitor， the second exothermic peak value increases by 66.93%， the time of the peak is delayed by 2.75 h， the third exothermic peak value decreases by 20.38%， and its appearance time is delayed by 9.28 h.

Mechanism of FeSO₄·H₂O Synergistic with DTPA Modified Magnesium Oxychloride Cement

SU Hui, ZHANG Linkang, BAI Yanjie, LYU Jiaxin, ZHANG Xin, NAN Bowen, PI Haojun

2026, 45(5):  1491-1500.  doi:10.16552/j.cnki.issn1001-1625.2025.1086

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In this study， the effects of ferrous sulfate monohydrate （FeSO₄·H₂O） and diethylene triamine pentaacetic acid （DTPA） on setting time， mechanical properties， water resistance and microstructure of magnesium oxychloride cement （MOC） were investigated. The mechanism of water resistance improvement of MOC by FeSO₄ ·H₂O and DTPA was revealed. FeSO₄·H₂O and DTPA were added to MOC in different proportion from 0% to 2% （mass fraction）. The results show that when 2% FeSO₄·H₂O and 2% DTPA are added， the performance of MOC is significantly optimized. The initial setting time and final setting time are extended to 339 and 374 min， respectively， which are 120% and 81% higher than those of the control group （without FeSO₄·H₂O and DTPA）. At the same time， the 7 d softening coefficient is increased to 0.9， which is 164% higher than that of the MOC group. The 28 d compressive strength reaches 130 MPa， which is 76% higher than that of the group control， and the porosity is also significantly reduced. This is attributed to the fact that the carboxyl structure of DTPA chelates Mg²⁺， which provides the active site for Mg²⁺ in the MOC system， so that the 5Mg（OH）₂·MgCl₂·8H₂O （5·1·8 phase） crystals are arranged more closely and the structure is denser. At the same time， the gel-like 5·1·8 phase crystals are formed to fill the micropores between the crystals， thus significantly improving the water resistance of MOC.

Multivariate Modification Strategy of EPS and Its Application in Lightweight Cement Mortar

PANG Chaoming, LIAO Baohong, WANG Shaohua

2026, 45(5):  1501-1512.  doi:10.16552/j.cnki.issn1001-1625.2025.1015

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To meet the development needs of lightweight building materials， this study addressed the issue of poor hydrophilicity of expanded polystyrene （EPS） particles by conducting a series of hydrophilic modification experiments and systematically investigated the influences of modified EPS particles on mortar properties. Single or composite surface modifications were applied to unexpanded polystyrene （PS） raw particles using polyvinyl acetate emulsion （PVAc）， sodium silicate （SS）， hydroxypropyl methylcellulose ether （HPMC）， and bentonite （BT）. After the expansion and foaming of PS raw particles，EPS lightweight mortars with density grades of 1 100 and 1 400 kg/m³ （D11 and D14） were prepared， their fluidity， compressive strength， water absorption， drying shrinkage， thermal conductivity，sound absorption and insulation properties， as well as microscopic interfacial morphology， were examined. The results show that that surface modification of PS raw particles significantly enhances the surface hydrophilicity of EPS particles， effectively improves the interfacial bonding between the foamed particles and the cement matrix， and thereby comprehensively enhances mortar performance. The maximum compressive strength reaches 10.3 MPa （an increase of 87.3% increase） for the D11 and 21.8 MPa （an increase of 61.5% ） for D14. The water absorption and drying shrinkage of mortar decrease， with maximum drying shrinkage reductions of 44.0% （D14） to 53.9% （D11）.Furthermore， the thermal conductivity of the mortar remains at a low level of 0.070~0.122 W/（m·K）， demonstrating potential for integrated self-insulation and structural applications.

Experimental Study on Mechanical Performance of PVA-ECC Strengthening and Toughening Units Prepared by Freezing

REN Jun, TUO Mintai, MAO Jianghong, CHEN Changyu, ZENG Gensheng, LIU Xiangyun, LI Zhong

2026, 45(5):  1513-1526.  doi:10.16552/j.cnki.issn1001-1625.2025.1078

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The fabrication of strengthening and toughening units using fiber-reinforced engineered cementitious composites is recognized as an effective approach to enhancing the mechanical performance of structural components. Polyvinyl alcohol engineered cementitious composite exhibits high ductility， pronounced strain-hardening behavior， and excellent crack-control capability， making it particularly suitable for embedding as localized functional reinforcement within normal concrete structures. Despite these advantages， existing techniques face substantial limitations. Achieving stable interface bonding while enabling flexible and directional placement of reinforcement units remains challenging， and further investigation is required to develop embedded directional strengthening methods capable of reinforcing structurally weak regions within concrete elements. Liquid nitrogen quick-freezing offers a potential solution by imparting controllable shape stability to the cementitious matrix. This approach allows strengthening and toughening units to be geometrically parameterized and optimally oriented according to localized stress distributions， enabling precise control over spatial placement， orientation， and scale. By rapidly arresting early hydration， quick-freezing preserves microstructural integrity and prevents the formation of coarse ice crystals that could compromise fiber-matrix interaction. Subsequent controlled thawing resumes hydration and restores mechanical performance. This technique introduces a novel strategy for directional toughening in engineered cementitious composites （ECC）-normal concrete （NC） composite systems and provides a framework for systematic material-level evaluation. To validate the feasibility of this concept， the present study focuses on the material performance of polyvinyl alcohol fiber-reinforced engineered cementitious composite units. Strengthening and toughening units were fabricated using two freezing protocols： slow-freezing and liquid nitrogen quick-freezing， followed by controlled thawing at predetermined temperatures. Mechanical performance was evaluated through 28 d compressive and uniaxial tensile tests， while multi-scale characterization was conducted using digital image correlation （DIC）， X-ray diffraction （XRD）， and scanning electron microscopy （SEM） to investigate strain localization， hydration progression， microstructure， and fiber-matrix interface integrity. Experimental results indicate that quick-freezing combined with subsequent thawing effectively preserves mechanical performance. Compressive strength of quick-frozen units recovered to 96.6% and 98.8% of the standard-cured reference values under two thawing conditions （40 and 60 ℃）， while tensile properties， including first-cracking stress， peak stress， and ultimate strain， were essentially comparable to the reference group. In contrast， slow-freezing induced substantial mechanical degradation： compressive strength decreased by 38.5%， and peak tensile stress and ultimate strain decreased by 42.3% and 34.3%， respectively. Multi-scale analyses revealed that quick-freezing and thawing maintained fine， uniformly distributed multiple-cracking patterns and a dense interfacial structure， whereas slow-freezing resulted in hindered hydration， a more porous matrix， and impaired fiber-bridging performance. These findings demonstrate that liquid nitrogen quick-freezing provides distinct advantages for fabricating strengthening and toughening units with controllable geometry and preserved performance. The results offer a robust experimental foundation for embedding pre-fabricated units in critical regions of concrete structures to enhance mechanical performance and support subsequent optimization of interface synergy with surrounding concrete. This study establishes the material basis and practical evidence necessary to inform further research on ECC-NC composite structural applications and interface engineering.

Mechanical Properties of Ferroaluminate Cement-Based Materials Reinforced by Hybrid Fiber

LIU Zhan, MEI Junpeng, DU Yonghui, GUO Hanyu, YANG Shilin

2026, 45(5):  1527-1535.  doi:10.16552/j.cnki.issn1001-1625.2025.1007

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To enhance the toughness of ferroaluminate cement-based materials， this research presented the design of a multi-scale hybrid fiber composite system through the incorporation of polyoxymethylene （POM） fiber and polypropylene （PP） fiber. The impact of this system on the fundamental mechanical properties of ferroaluminate cement mortar， including fluidity， flexural strength， compressive strength， ultimate tensile strength， and bending strength was examined. Furthermore， scanning electron microscopy was employed to examine its microstructure. The results indicate that the impact of hybrid fibers on the fluidity of ferroaluminate cement is less significant than that of single type fiber. POM fiber can significantly enhance the flexural strength of cement when two types of fiber are mixed. Both single and composite fiber incorporations can markedly enhance the deflection capacity of ferroaluminate cement-based materials. When the volume fractions of PP fiber and POM fiber are both 0.3%（mass fraction）， the hybrid fiber system demonstrates a remarkable “positive hybrid effect”， resulting in the maximum enhancement of equivalent bending strength. Microscopic examination reveals that POM fiber and PP fiber can synergistically operate across various dimensional scales to collectively impede fracture propagation， thereby enhancing the toughness of ferroaluminate cement-based materials.

Effect of Nano-Silica Content on Freezing Temperature of Concrete

LI Meng’en, QIN Yanhui, YIN Jinshuai, ZHENG Zihao, MA Haoyuan, LI Shuo

2026, 45(5):  1536-1544.  doi:10.16552/j.cnki.issn1001-1625.2025.0991

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Currently， research on the freeze-thaw durability of nano-silica （NS） enhanced concrete primarily focuses on the influence of different NS content， while quantitative studies on the freezing temperature of NS-modified concrete are still lacking. Although existing theories and mechanistic studies suggest that NS may lower the freezing temperature of concrete， experimental data and quantitative analyses are still relatively scarce. In this work， physical experiments were conducted to measure the temperature variation curves of C40 concrete with different NS content， and the freezing temperature was quantitatively characterized. Microscopic analysis of the pore structure was performed using the nuclear magnetic resonance （NMR） technology. The results show that within the experimental content range （0%， 1%， 2%， and 3%， mass fraction）， the freezing temperature of concrete decreases significantly with increasing NS content. When the NS content is 2%， the optimization effect on the pore structure is most remarkable， and the relative reduction in freezing temperature is most pronounced， particularly as the NS content increases from 1% to 2%. The results of this study supplement the research on the effect of NS on the freezing temperature of concrete， provide a reference for further investigation into the freeze-thaw damage mechanism of NS-modified concrete， and offer a basis for optimizing NS content in concrete engineering in different cold regions.

Comprehensive Evaluation of Crack Resistance, Carbon Emissions, and Cost for Ballastless Track Bed Slab Concrete

FANG Lei, LIN Ju, YUAN Qiang, CAI Huangyi, XU Song

2026, 45(5):  1545-1558.  doi:10.16552/j.cnki.issn1001-1625.2025.1066

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Reducing the risk of early?age cracking in track bed slab concrete is a critical issue in the application of double block ballastless tracks. However， existing methods for improving the crack resistance of track bed slab concrete often overlook the impacts on carbon emission and economic efficiency. To address this， this study proposed a low?shrinkage， high?crack?resistance track bed slab concrete， which incorporated low heat cement combined with shrinkage-reducing admixture， expansive agent， and fiber. Cracking factor η was defined as the ratio of the maximum tensile stress σ to the tensile strength f_t. From life cycle assessment， the carbon emission amount of concrete with different mix proportion was compared. Finally， a multidimensional comprehensive evaluation of cracking factor， modification cost， and carbon emission amount of track bed slab concrete was conducted using entropy-analytic hierarchy process （AHP）. The results show that the optimal mix proportion consists of low heat cement combined with 2%（mass fraction） shrinkage?reducing admixture， 8%（mass fraction） expansive agent， and 0.3%（mass fraction） fiber. Compared with conventional track bed slab concrete， the optimal concrete mix proportion reduces the cracking risk by approximately 80%， and the raw material?related CO₂ emission reduces by 11.53 t per kilometer of track bed. This research has guiding significance for the mix proportion design of low?carbon and high?crack?resistance track bed slab concrete and the comprehensive evaluation of cement?based materials properties， environmental and economic benefits.

Research on Mechanical Properties of Nanomaterial and Fiber Modified Tunnel Spoil Concrete

YANG Taihua, WANG Gonglue, LUO Xufeng, ZHOU Zhe, TU Ming, LIU Bin, LIU Xuewei

2026, 45(5):  1559-1570.  doi:10.16552/j.cnki.issn1001-1625.2025.1000

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To enhance the mechanical properties of tunnel spoil concrete and promote the sustainable utilization of mineral waste， an orthogonal test was conducted to investigate the effects of varying contents of nano-silica， fly ash， and basalt fibers （with lengths of 6 and 12 mm） on the mechanical properties of tunnel spoil concrete. Based on macro- and micro-scale test results， the optimal mix proportion was determined， and the mechanisms of influences of these materials on the concrete’s performance were clarified. The results indicate that the overall properties of the modified tunnel spoil concrete reach their optimum with the incorporation of 1% （mass fraction） nano-silica， 10% （mass fraction） fly ash， 0.15% （volume fraction） of 6 mm basalt fiber， and 0.1% （volume fraction） of 12 mm basalt fiber. Compared with the unmodified tunnel spoil concrete， the compressive strength and splitting tensile strength of the modified concrete increase by up to 20.0% and 26.3%， respectively. Fly ash and nano-silica promote the formation of C-S-H gel during the hydration process. The fibers enhance the splitting tensile performance， ultimately improving both the mechanical properties and failure mode of the concrete.

Early Strength Prediction Model of Underwater Pile Foundation Concrete and Demolition Age of Casing

LI Xiaoqing, WANG Pu, FANG Qixing, WU Peng, TIAN Weijun, DANG Yue, LIU Jinxin, XU Xiangtian

2026, 45(5):  1571-1579.  doi:10.16552/j.cnki.issn1001-1625.2025.1039

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Existing testing methods are difficult to monitor the actual strength of concrete in underwater pile foundation casing and fail to accurately evaluate the compressive strength of underwater pile foundation concrete. To reveal the early compressive strength development law of underwater pile foundation concrete， this study used the independently developed temperature control and self-balancing pressure curing equipment to simulate the underwater pile foundation condition and conducted the influences of different self-weight heights， curing temperatures and curing ages on the early compressive strength of pile foundation concrete. The results show that， compared with standard curing， the compressive strength of concrete specimens simulated underwater curing for 7 d is increased by 6.56%. Curing age is the main factor affecting the early compressive strength of pile foundation concrete， followed by curing temperature， and the influence of self-weight height is relatively weak. Prolonging the curing age improves the improvement effect of curing temperature on the compressive strength of underwater pile foundation concrete. Based on the maturity theory， a prediction model for the early age strength of underwater pile foundation concrete is established， with the relative error between predicted and measured values within 7.0%. Combined with the engineering case of the Guijiang Grand Bridge on the Pingzhao Expressway， the demolition age of the casing is shortened from 17 d to 5 d. The research results provide a reliable basis for the early bearing capacity evaluation and construction decisions of underwater pile foundation.

Preparation of Silica-Modified Epoxy Coating and Its Protective Performance on Steel Bars

KONG Shuo, GENG Yongjuan, LIU Yancen, LI Shaochun

2026, 45(5):  1580-1590.  doi:10.16552/j.cnki.issn1001-1625.2025.1002

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To enhance the comprehensive performance of epoxy resin （EP） coatings in steel reinforcement protection， this study addressed issues such as high brittleness， high porosity， and weak interfacial bonding.Nano-SiO₂ （NH₂-SiO₂） was modified by γ-aminopropyl triethoxysilane （γ-APS） to prepare amino functional nano-SiO₂， which was introduced into epoxy resin to prepare NH₂-SiO₂/EP composite coating.FTIR， TGA， and XPS analyses confirm successful modification： amino functional groups are successfully grafted on the surface of SiO₂ by chemical bonding， improving dispersion and interfacial compatibility of nanoparticles in epoxy matrix. SEM and EDS analysis reveal optimal coating density with uniform particle distribution at 3%（mass fraction） NH₂-SiO₂ content. Research indicates that the 3%-NH₂-SiO₂/EP composite coating exhibits approximately 75% higher tensile strength than pure epoxy resin， and the maximum load is 2.2 kN； while reducing coefficient of friction from 0.97 to 0.77， demonstrating significant wear resistance improvement. Electrochemical impedance spectroscopy （EIS） results indicate that the coating maintained impedance modulus is still above 1×10¹¹ Ω·cm² after 3 d immersion in 3.5%NaCl concrete simulated corrosion solution， showing excellent corrosion resistance. This study provides a theoretical basis for design and application of anti-corrosion coating for high performance steel bars.

Solid Waste and Eco-Materials

Research Progress on Effect of Rice Husk Ash on Properties of Cementitious Materials

WANG Jianfeng, LIN Kaihao, LAI Haocheng, SONG Yifang, JIANG Yiming, LI Na, WANG Wei

2026, 45(5):  1591-1602.  doi:10.16552/j.cnki.issn1001-1625.2025.0953

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Rice husk ash （RHA）， a by-product of rice husk combustion， possesses unique physical and chemical properties with potential as a cementitious material admixture.Incorporating RHA into cementitious materials not only enhances the resource utilization rate of rice husk as agricultural waste but also helps mitigate the issues of high energy consumption and environmental pollution associated with cement production. This paper systematically describes the physical and chemical properties of RHA and analyzes the influence of rice husk pretreatment methods on its performance. Subsequently， it comprehensively reviews the effects and mechanisms of RHA on the workability， mechanical properties， and durability of cementitious materials. Finally， it summarizes the shortcomings in existing research and outlines future research directions， aiming to provide a reference for further study and application of RHA in cementitious materials.

Triaxial Mechanical Properties of Bamboo Stem Biochar-Modified Cement-Stabilized Soil

KONG Aisan, HONG Yalu, YE Minhui, WU Hongxiang, TANG Wei, LI Na, WANG Wei

2026, 45(5):  1603-1614.  doi:10.16552/j.cnki.issn1001-1625.2026.0041

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To investigate the modification effect of bamboo stem biochar on cement-stabilized soil at different curing ages， this study examined the mechanical properties of bamboo stem biochar-modified cement-stabilized soil （BBMCS） specimens， including deviatoric stress-strain curves， peak deviatoric stress， internal friction angle， and cohesion， via unconsolidated-undrained （UU） triaxial tests. The results indicate that bamboo stem biochar improves the morphology of the stress-strain curves of cement-stabilized soil by optimizing its internal structure. The deviatoric stress-strain curves of all BBMCS specimens exhibit strain-softening behavior， characterized by brittle failure. At curing ages of 7 and 28 d， BBMCS specimens with a bamboo stem biochar content of 6% （by mass） demonstrate optimal mechanical properties， with their peak deviatoric stress increasing by 89% and 81%， respectively， compared to the control group without bamboo stem biochar. The enhancement of mechanical properties in BBMCS by bamboo stem biochar is primarily attributed to the improvement of cohesion， with no significant effect observed on the internal friction angle. Based on the experimental data， a quadratic prediction model relating bamboo stem biochar content， confining pressure， and peak deviatoric stress at different curing ages was established. The predicted values show good agreement with the measured values. These findings provide basis for the engineering application of BBMCS.

Model Test of Carbonized Photovoltaic Piles Based on Solid Waste Fly Ash

ZHU Xitong, LI Chi, LIU Yang, WANG Xiaorong

2026, 45(5):  1615-1625.  doi:10.16552/j.cnki.issn1001-1625.2025.1072

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In centralized photovoltaic projects， a large amount of cement is consumed in foundation construction， which not only depletes natural resources but also exerts negative impacts on the environment. Therefore， exploring and applying alternative curing materials to replace cement has become a crucial direction for the photovoltaic industry to achieve green and low-carbon development. Focusing on the core goal of cement reduction， this study used circulating fluidized bed fly ash （CFBFA） and flue gas desulfurization gypsum （FGD） as mineral admixtures， and prepared photovoltaic pile foundations by combining carbonation curing technology. Carbonation tests， concrete strength tests， and indoor model tests were carried out to systematically analyze the solid waste absorption capacity and engineering performance of this technology. The results show that carbonation curing can improve the mechanical properties of concrete by optimizing its pore structure： after 28 d carbonation curing， the solid waste concrete with 30% CFBFA and 3% FGD （mass fraction） achieves a compressive strength of 45.2 MPa and a splitting tensile strength of 5.5 MPa， which are 55.3% and 89.7% higher than those of the solid waste group under standard curing， respectively. In addition， the ultimate uplift bearing capacity of the solid waste-based photovoltaic pile is 6.7% higher than that of the traditional pile foundation， and its pile side friction resistance performs better. When the carbonation curing technology for solid waste-based photovoltaic piles is applied to prepare foundations for every 1 000 photovoltaic panels， it can reduce standard coal consumption by 42.2 kg/t， decrease electricity and resource consumption by 33.0%， and absorb 29.4 t of CFBFA and 2.9 t of FGD simultaneously. In conclusion， the carbonation curing technology for solid waste-based photovoltaic piles can significantly reduce cement usage in photovoltaic projects and achieve the dual goals of solid waste resource utilization and carbon emission reduction.

Mechanical Properties of Nano-SiO₂ Modified GGBS-Fly Ash Geopolymer-Stabilized Soil

HU Jianlin, TAO Xilong, LI Yaru, JIA Tianyao, WU Chunping, MENG Zhipeng, ZHOU Yongxiang

2026, 45(5):  1626-1637.  doi:10.16552/j.cnki.issn1001-1625.2025.0958

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To address the issues of high energy consumption， significant carbon emissions， low early strength， and poor water stability in cement-stabilized soil， this study used ground granulated blast-furnace slag （GGBS） and fly ash as precursors， water glass as activator to prepare geopolymer， and added nano-SiO₂ to solidify the soil. Through unconfined compressive strength tests and water stability tests， combined with microscopic analyses including scanning electron microscopy， energy-dispersive spectroscopy， and nitrogen adsorption， the effects of nano-SiO₂ content and curing age on the mechanical properties of geopolymer-stabilized soil were investigated. The results indicate that the unconfined compressive strength of geopolymer-stabilized soil initially increases and then decreases with increasing nano-SiO₂ content， with an optimal nano-SiO₂ content of 0.6% （mass fraction）. When the mass ratio of GGBS to fly ash is 5∶5， 7∶3， and 9∶1， the unconfined compressive strength is 16.0%， 22.4% and 26.5%， respectively， higher than that of the undoped nano-SiO₂ specimen. The higher the content of GGBS is， the more significant the effect of nano-SiO₂ on the unconfined compressive strength of geopolymer-solidified soil is. With the increase of curing age， the unconfined compressive strength of geopolymer-stabilized soil gradually increases， but the effect of nano-SiO₂ on the unconfined compressive strength decreases. When the mass ratio of GGBS to fly ash is 7∶3， the strength growth rates at 7， 14， and 28 d for specimens with nano-SiO₂ are 22.4%， 15.4%， and 6.0%， respectively， relative to those without nano-SiO₂. The incorporation of nano-SiO₂ improves the water stability and reduces the strength loss rate of the specimens. Microscopic analysis reveales that nano-SiO₂ enhances the compressive strength and water stability of geopolymer-stabilized soil through chemical reactions， particle filling， and nucleation effects. Nitrogen adsorption test results show that with increasing nano-SiO₂ content， the cumulative pore volume and the proportion of large pores in the specimens first decrease and then increase， which is consistent with the change of mechanical properties.

Hydration Properties of Polyvinyl Alcohol-Modified Slag-Fly Ash-Based Alkali-Activated Cementitious Materials

LI Binghan, LI Shiji, ZHAO Yimeng, LIU Yunpeng, XU Da, ZHAO Shuli

2026, 45(5):  1638-1649.  doi:10.16552/j.cnki.issn1001-1625.2025.1009

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Although alkali-activated cementitious materials exhibit lower greenhouse gas emissions and mechanical properties comparable to those of Portland cement， they suffer from problems such as significant drying shrinkage， susceptibility to cracking， and notable performance fluctuations. Incorporating polyvinyl alcohol （PVA） can effectively reduce drying shrinkage， enhance flexural strength and toughness， and promote structural densification. This study systematically investigated the effects of different PVA content （0%， 2.5%， 5.0%， 7.5%， and 10.0%， mass fraction） on the fluidity， setting time， hydration heat， compressive strength， flexural strength， drying shrinkage， mass loss， pH value， water absorption rate， and microstructure of slag-fly ash-based alkali-activated cementitious materials. The results show that as the PVA content increases， the paste fluidity decreases and the final setting time is prolonged； both the hydration heat release rate and cumulative heat release decrease； the compressive strength decreases with higher PVA content， whereas the flexural strength improves after 28 d of curing， with the highest flexural strength （6.63 MPa） achieved at a PVA content of 5.0%； drying shrinkage is reduced when the PVA content does not exceed 5.0%， but increases when the content exceeds 5.0%； the introduction of PVA also leads to a decrease in paste pH value and an increase in water absorption rate. Microstructural analysis indicates that PVA films and hydration products mutually encapsulate and fill each other， forming a composite structure that enhances the microscopic densification of the material. This study clarifies the regulatory effect of PVA on the hydration behavior and macroscopic properties of alkali-activated cementitious materials， providing a basis for their engineering applications.

Effect of Dry and Wet Treatment on Cementitious Activity of Stainless Steel Slag and Environment

CHEN Meizhu, CHEN Tong, CHEN Dongyu, WU Yongwei

2026, 45(5):  1650-1662.  doi:10.16552/j.cnki.issn1001-1625.2025.0959

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The cementitious activity of stainless steel argon oxygen decarburization （AOD） slag is found to be significantly influenced by its processing method. In this study， a systematic comparison of the physicochemical properties was conducted between dry-processed and wet-processed AOD slag using various characterization methods including XRD， XRF， BET， and TCLP， complemented by cement mortar performance tests.The results demonstrate that， compared to wet-processed slag， the dry-processed slag exhibits a 3.63% increase in apparent density， a reduction in D₅₀ to 23.37 μm， and a specific surface area of 1.13 m²/g. The pH value of the leachate increases from 9.7 to 10.5. Moreover， the total CaO and SiO₂ content are decreased by 2.14% （mass fraction）， the β-C₂S phase content is reduced， and the basicity drops from 2.01 to 1.96. At 30% mass replacement of cement by AOD slag， compared with the wet-processed slag， the cement mortar containing dry-processed slag shows a 48.62% increase in cumulative heat release. The initial fluidity increases by 6.03%， and the initial and final setting times are shortened by 39 and 29 min， respectively. 28 d flexural strength activity index and compressive strength activity index reach 88.13% and 53.45%， respectively， which are 10.71% and 6.96% higher than those of the wet-processed slag， confirming that AOD slag after dry processing exhibits superior cementitious activity and environmental safety. These findings of this study provides theoretical and technical support for the high-value utilization of stainless steel AOD slag.

Carbon Sequestration Performance of Steel Slag-Based Foamed Concrete under Different Material Compositions and Curing Processes

TANG Xiaosong, SONG Qiulei, LUO Jingjing, ZHANG Cheng, ZHANG Yuyang

2026, 45(5):  1663-1670.  doi:10.16552/j.cnki.issn1001-1625.2025.0965

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To elucidate the regulatory mechanisms governing the carbon sequestration performance and mechanical properties of steel slag-based foamed concrete （SSFC）， and to explore innovative pathways for the resource utilization of steel slag as well as the development of novel carbon-sequestering building materials， this study investigates the effects of steel slag content， carbonation time， and carbonation pressure on the CO₂ absorption rate and compressive strength of SSFC， and proposes a technical approach to enhance its carbon sequestration performance through of SSFC the synergistic use of pre-curing and an early-strength agent.The results indicate that increasing steel slag content， prolonging carbonation time， and elevating carbonation pressure progressively enhance the CO₂ absorption rate of SSFC. The compressive strength initially increases and subsequently decreases with higher steel slag content （peaking at 70% steel slag content by mass fraction）， and the compressive strength increases with the increase of carbonation time. Moreover， the synergistic effect of pre-curing and early-strength agents significantly improves carbon sequestration performance of SSFC. Under optimal conditions （70% steel slag content， 0.4% Li₂CO₃ content （mass fraction）， 5 d standard curing， and 0.3 MPa pressure for 24 h carbonation）， SSFC achieves a 13.0% CO₂ absorption rate with 6.9 MPa compressive strength， this study provides novel insights for developing next-generation carbon-sequestering foamed concrete.

Effect of Microbial-Modified Phosphogypsum on Properties of Supersulfated Cement

REN Jun, YAN Yunxiao, LI Miaoyuan, TIAN Zhenhe, ZHAO Lixing, WANG Dafu

2026, 45(5):  1671-1681.  doi:10.16552/j.cnki.issn1001-1625.2025.1025

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In the context of global carbon peaking and carbon neutrality goals， the development of low-carbon， low-energy-consumption cementitious materials has become an important trend in the field of building materials. Supersulfated cement （SSC）， as a green cementitious material mainly composed of granulated blast-furnace slag， phosphogypsum and a small amount of cement clinker， has the advantages of low calcination energy consumption and high industrial solid waste utilization. However， untreated phosphogypsum contains harmful impurities such as phosphorus and fluorine， which seriously inhibit the hydration process of SSC， leading to long setting time and low early strength， limiting its large-scale engineering application. Traditional modification methods such as water washing and alkali washing have problems such as low impurity removal efficiency， high energy consumption， and secondary pollution.This study aims to systematically explore the effects of water washing， alkali washing， microbial treatment and microbial-alkali synergistic treatment on the macro-performance and microstructure of SSC， and reveal the enhancement mechanism of microbial modification. On the basis of the optimized mix ratio of m（slag）∶m（phosphogypsum）∶m（cement clinker）=0.84∶0.13∶0.03， the standard consistency water demand， setting time， and compressive strength of SSC were tested in accordance with Chinese national standards. The hydration products， micromorphology， pore structure and thermal stability were characterized by XRD， SEM， MIP and TG/DTG.The results show that all modification treatments can effectively improve the performance of SSC， and the microbial-alkali synergistic treatment shows the best effect. Microbial treatment increases the standard consistency water demand of SSC， shortens the initial and final setting time， which are about 20% and 30% shorter than those of the untreated group， and significantly improves the compressive strength. Compared with the control group， the 3 d compressive strength increases by 298%~349%， and the 28 d compressive strength still increases by 40%~58%. Microbial modification removes 40.24%~53.33% of total phosphorus and 34.91%~48.11% of fluoride impurities， reduces the median particle size of phosphogypsum， raises the pH value of the pore solution by about 0.98 units， and promote the formation of C-S-H gel， ettringite and calcium carbonate. Microscopic characterization shows that microbial treatment optimizes the pore structure， increases the proportion of harmless pores below 20 nm， reduces the total porosity， and makes the matrix denser.The innovation of this study lies in the first systematic comparison of multiple modification methods of phosphogypsum， clarification of the evolution pattern of bacteria in the hydration process of SSC. Bacterial cell walls act as nucleation sites to adsorb Ca²?， and the lysed organics further promote biomineralization， forming a synergistic mechanism of impurity removal， alkalinity improvement， nucleation promotion and pore filling. This research provides a green and efficient modification route for the high-value utilization of phosphogypsum， enriches the application theory of biomineralization in cement-based materials， and offers important academic value and engineering guidance for the development of high-performance low-carbon cement.

Settlement Law of Recycled Brick Aggregate in Foamed Concrete Slurry

LIU Yunxiao, TANG Zhenghui, HAN Yingbo, DING Yiming, ZHOU Hui, LI Xiaoguang, LIANG Kun

2026, 45(5):  1682-1692.  doi:10.16552/j.cnki.issn1001-1625.2025.1050

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Using foamed concrete for back-filling effectively resolves the issue of "vehicle bumping at bridgeheads". However， this method is associated with high costs and significant hydration heat release. Incorporating recycled brick aggregate （RBA） into foamed concrete as a dumped rip-rap concrete not only simplifies the construction process， but also reduces the hydration heat of foamed concrete and lowers costs. Nevertheless， it remains uncertain whether RBA particles of varying sizes will continue to settle to the bottom of foamed concrete slurry， which may potentially compromise the quality of the back-filling construction. In this study， finite element analysis software was utilized to develop a settlement model for simulating the settling behavior of RBA particles in foamed concrete. Furthermore， the effects of rheological parameters， RBA size， and dumping height were systematically examined. As particles move through a slurry， the final motion state of the particles is independent of the dumping height in an infinitely deep slurry. Yield stress of the slurry determines whether the particles are continuously settling or hovering in the slurry， while plastic viscosity dictates the terminal settling velocity. The minimum particle size of RBA that can settle to the bottom of the slurry can be determined by testing the density and yield stress of the slurry. To facilitate engineering applications， the critical particle size—the smallest particle size can settle to the bottom— of RBA in the five types of foamed concrete slurries at dumping heights ranging from 1 m to 3 m is presented.

Solidification of Red Mud Based on Geopolymerization and Nanomaterial Composite Optimization

TIAN Shumei, LUO Haowen, WANG Hongxing, RUAN Junhao, ZHAO Tiantian, ZHANG Xiaoyi, WU Shangwei

2026, 45(5):  1693-1708.  doi:10.16552/j.cnki.issn1001-1625.2025.1026

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The resource utilization of red mud has long been limited by its high pH value characteristic. A red mud solidification technology based on synergistic reactions of solid wastes and optimized compounding of nanomaterials was proposed by the reverse utilization of the strongly alkaline environment of red mud， the geopolymerization potential of solid wastes such as fly ash and mineral waste residue， and the filling-dispersion function of nanomaterials. Orthogonal mechanical experiments were designed to obtain the optimized mix proportions for the red mud solidification， aided by the variance and range analyses. Scanning electron microscopy and X-ray diffraction analyses were conducted on typical ratio samples to reveal the solidification mechanism of red mud， aided by micro-pore structure analysis. The results indicate that the optimal mass ratio for red mud solidification is m（metakaolin）∶m（fly ash）∶m（mineral waste residue）∶m（calcium chloride）∶m（sodium silicate）∶m（nano-SiO₂）∶m（nano-Al₂O₃）∶m（carbon nanotube）=20.00%∶25.81%∶12.90%∶7.74%∶7.74%∶23.46%∶1.16%∶1.16%. The products of geopolymerization and hydration-hydrolysis reactions are both detected in all the samples. Dissolution rate and degree of chemical reaction completion of silicon-aluminum substances are improved， and the elongated pores larger than 1.0 μm are better filled， through the silicon-aluminum ratio regulation by the nanomaterial adjustments， to optimize the microstructure of the solidified red mud and provide strength assurance for it. This technology achieves a high red mud incorporation rate of 80% （mass fraction）， providing a new strategy for the resource utilization of bulk solid wastes.

Ceramics

Research Progress of Porous Ceramic Materials for Transpiration Cooling

JIANG Li, WANG Honglei, ZHOU Xingui, YU Jinshan

2026, 45(5):  1709-1726.  doi:10.16552/j.cnki.issn1001-1625.2025.1036

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Hypersonic vehicles face severe thermal protection challenges under extreme service conditions， where traditional passive thermal protection technologies struggle to meet the demands for long-term， reusable thermal management requirements. Transpiration cooling is an efficient active thermal protection technology. Porous media materials used for transpiration cooling need to possess characteristics such as high-temperature resistance， lightweight， and high permeability. Porous ceramic materials for transpiration cooling， with their low density， high specific surface area， excellent high-temperature oxidation resistance， and low thermal expansion coefficient， have emerged as ideal candidate materials. This article systematically reviews the working principles and advantages of transpiration cooling technology， focusing on the performance characteristics and main preparation methods（including template replication method， partial sintering method， pore-forming agent addition method， direct foaming method， and additive manufacturing） of porous ceramics. It compares the advantages and disadvantages of different methods and highlights the current challenges in balancing high porosity with mechanical properties， achieving complex structural shaping， and precisely controlling gradient porosity. Finally， this article outlines future research directions， such as precise pore structure regulation and the construction of multiphase ceramic systems， to promote the industrial application of these materials in aerospace thermal protection.

Laser Ablation Behavior and Development Trend of Ceramic Matrix Composites

ZHANG Yunzhe, CHEN Minsun, WANG Honglei, ZHOU Xingui, YU Jinshan

2026, 45(5):  1727-1740.  doi:10.16552/j.cnki.issn1001-1625.2025.1118

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With the extensive application of high-energy laser technology in military and industrial fields， the laser ablation behavior and protection mechanisms of ceramic matrix composites have become a hot topic in cutting-edge research. This paper systematically reviews the ablation mechanism， dynamic response behavior， and anti-ablation protection strategies of ceramics and ceramic matrix composites under laser irradiation. Firstly， the basic physical processes of laser-material interaction are elaborated， including photon-electron coupling， energy absorption， and heat conduction mechanisms， and the influences of parameters such as laser power， wavelength， and pulse mode on the ablation morphology and evolution of the heat-affected zone are analyzed. On this basis， the ablation behaviors of typical carbide （such as C/SiC， SiC_f/SiC）， oxide （such as Al₂O₃/Al₂O₃）， and nitride （such as Si₃N₄， AlN） matrix composites under different laser conditions are further summarized， including material removal mechanisms， oxidation kinetics， phase transformation processes， and microstructure evolution， and the influences of external factors such as supersonic gas flow and environmental atmosphere on the ablation process are discussed. In terms of protection， the design concepts， performance advantages， and research progress of reflective， ablation-resistant， thermal insulation， and composite protective coatings are systematically discussed， covering the development and application potential of new protective systems such as high-reflection ceramic modification， multi-layer structure design， high-entropy ceramics， and biomimetic gradient materials， providing theoretical basis and technical paths for the research and engineering application of high-performance laser ablation-resistant materials.

Preparation of Iron-Loaded Porous Ceramics by Polyurethane Foaming and Low-Temperature Sintering Method

WEI Mingmin, FAN Zimin, ZHAO Xiaofeng, WANG Guofei, SUN Ying, MAO Yulan, DUAN Xiaobo

2026, 45(5):  1741-1748.  doi:10.16552/j.cnki.issn1001-1625.2025.1049

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Iron tailings were employed as the primary raw material to fabricate iron-loaded porous ceramics （IT-PC） with a sponge-like interconnected pore structure via a polyurethane foaming and low-temperature sintering process at a sintering temperature of 650 ℃. The effect of polyurethane content on the microstructure， phase composition， apparent porosity， water absorption， bulk density， and compressive strength of the resulting IT-PC were systematically investigated. The results indicate that quartz and hematite are the major crystalline phases of IT-PC. Polyurethane foaming forms a three-dimensional skeletal template within the slurry， directly determining the material’s apparent porosity， pore connectivity， and pore size distribution. As the polyurethane content increases from 14%（mass fraction） to 22%， the apparent porosity rises from 61.60% to 87.65%， and the water absorption increases from 78.54% to 277.13%， whereas the bulk density decreases from 0.78 g·cm^-3 to 0.32 g·cm^-3， and the compressive strength drops from 2.80 MPa to 0.31 MPa. When applied as a heterogeneous Fenton catalyst carrier for acidic magenta degradation， this porous ceramics achieve a 95% removal rate with no detectable leaching of soluble iron ions. It demonstrates excellent structural stability and recyclability， exhibiting promising application potential in dye wastewater treatment.

Refractory Materials

Effect of Double-Doping Al and Si on Phase Reconstruction and Slag Erosion Resistance of Magnesia-Carbon Bottom-Blowing Elements

YAN Mingwei, ZHANG Lunliang, SUN Guangchao, YE Shufeng, LIU Kaiqi

2026, 45(5):  1749-1756.  doi:10.16552/j.cnki.issn1001-1625.2025.1035

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Magnesia-carbon bottom-blowing element for metallurgical furnace is typically enhanced by adding Al or Si to improve its performance. To investigate the effect of double-doping Al and Si on phase reconstruction and slag erosion resistance at high-temperature nitrogen environment， the magnesia-carbon bottom-blowing element specimens were prepared using fused magnesia， flake graphite， Al powder， and Si powder. The specimens were heat-treated in a 1 600 ℃ nitrogen atmosphere， and XRD， SEM， and EDS were employed to analyze the phase reconstruction and microstructure of the matrix of the Al single-doped and Al-Si double-doped specimens before and after erosion by slag. Results indicate that different from the Al single-doped specimen， the Al-Si double-doped specimen induces distinct phase transformations in the matrix， and double-doping Al and Si has an important effect on the slag erosion resistance. After the slag erosion experiment at 1 600 ℃ for 20 min， the Al single-doped specimen shows no significant slag adhesion on its contact surface with converter slag， with oxidation erosion layer less than 1 000 μm. In contrast， the Al-Si double-doped specimen develops a 300 μm oxidation erosion layer composed of spinel， Ca₃（Al_1-x Fe _x ）₂Si₃O₁₂， and 12CaO·7Al₂O₃， demonstrating that Si significantly influences phase reconstruction and slag erosion resistance of magnesia-carbon bottom-blowing elements and its excessive addition should be avoided.

Functional Materials

Research Progress on SiC_f/SiC Composites Prepared by NITE Process

YAO Xinrong, WANG Honglei, YU Jinshan, ZHOU Xingui

2026, 45(5):  1757-1776.  doi:10.16552/j.cnki.issn1001-1625.2025.0995

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Continuous silicon carbide fiber-reinforced silicon carbide ceramic matrix composites （SiC_f/SiC composites） are renowned for their exceptional mechanical properties， high-temperature stability， and irradiation resistance， rendering them ideal candidates for applications in the hot sections of aero-engines and nuclear reactors. The microstructure， properties， and application domains of these composites are significantly influenced by the fabrication routes employed. Among these， the nano-infiltration and transient-eutectic （NITE） process has gained prominence in the production of high-performance SiC_f/SiC composites， attributed to its short processing cycles， high densification， and excellent irradiation resistance. This review provides a comprehensive summary of the principles and optimization strategies associated with the NITE process for SiC_f/SiC composites fabrication. Furthermore， recent advancements in the high-temperature oxidation resistance， thermal conductivity， and irradiation resistance of SiC_f/SiC composites produced via the NITE process are examined. The article outlines current progress and identifies remaining challenges in the industrialization of the NITE process， explores hybrid methodologies combining NITE with other fabrication techniques， and discusses future research directions and prospects for NITE-based SiC_f/SiC composites.

Research Progress on Preparation of Hydrophobic Modification Zeolite and Its Application in Gas Purification Field

ZHU Hang, LI Yan, LI Yi, WANG Bo, WU Yanan, ZHANG Wei, LIU Wenjia, LI Ping, ZHANG Ke

2026, 45(5):  1777-1789.  doi:10.16552/j.cnki.issn1001-1625.2025.1018

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Zeolite is widely used in the field of gas separation and purification due to their regular microporous structure， high specific surface area and excellent adsorption selectivity. However， the surface of traditional zeolite is rich in silicon hydroxyl（—Si—OH ） and aluminum hydroxyl（—Al—OH ）， and it is easy to adsorb water molecules preferentially in high humidity gas system， which will lead to pore blockage and decrease of adsorption capacity of target gas， thus seriously limiting the applicability of zeolite to complex working conditions. The surface chemical properties and pore environment of zeolite can be regulated by hydrophobic modification， which can significantly improve the water resistance of zeolite and become the core technology to solve this problem. In this paper， the hydrophobic modification methods of zeolite （such as silane coupling agent modification， surface coating modification， dealumination modification and multi-method synergistic modification） are systematically reviewed， and the mechanism and modification effect of each method are expounded. The application progress of hydrophobic modification zeolite in CO₂ capture， volatile organic compounds （VOCs） removal and other pollutant purification is emphatically analyzed. Finally， the problems in the preparation of hydrophobic modification zeolite and its application in gas purification are put forward， and the development trend of hydrophobic modification zeolite is prospected.

Oxytetracycline Ratio Fluorescence Detection Based on Europium Metal-Organic Framework Encapsulated Cs₃Bi₂Br₉ Quantum Dots

ZHENG Jiahong, GUO Kang

2026, 45(5):  1790-1800.  doi:10.16552/j.cnki.issn1001-1625.2025.1054

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The specific detection of oxytetracycline （OTC） residues is of great significance for food safety and environmental monitoring. The rapid and specific determination of OTC in the environment remains a challenge. In this study， Cs₃Bi₂Br₉ was encapsulated in an Eu-based metal-organic framework （Eu-MOF） to construct a ratio fluorescence sensor， Cs₃Bi₂Br₉@Eu-MOF， for the detection of OTC. The results show that the sensor exhibits optimal performance when anhydrous ethanol is used as the anti-solvent and the preparation is carried out under an oil bath temperature of 60 ℃ and pH=7. The sensing mechanism indicates that， with increasing OTC concentration in the range of 0~16 μmol·L^-1， the blue fluorescence emission peak intensity of Cs₃Bi₂Br₉@Eu-MOF at 424 nm gradually decreases due to the inner filter effect， while a red fluorescence emission peak at 616 nm appears and its intensity gradually increases due to the sensitization of Eu³⁺ by OTC. Based on the ratio signal （F₆₁₆/F₄₂₄）， the Cs₃Bi₂Br₉@Eu-MOF ratio fluorescence sensor demonstrates high sensitivity and a low detection limit for OTC， and excellent selectivity and anti-interference ability.

Road Materials

Strength Properties and Microscopic Mechanism of Alkali-Activated Cementitious Materials Solidified Silty Clay under Dry-Wet Cycles

YAO Yong, LIANG Tian, HU Yanan, ZHANG Lingling, LIU Lei

2026, 45(5):  1801-1811.  doi:10.16552/j.cnki.issn1001-1625.2025.1031

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There are a large number of silty clay with strong water sensitivity in the northwest of Sichuan Province. The silty clay shows significant dry and wet vulnerability under the action of dry-wet cycle， which is easy to induce engineering problems such as subgrade settlement. The solidification of silty clay by alkali-activated cementitious materials can significantly improve its engineering performance， but the performance change of solidified soil under the action of dry-wet cycle is not clear. In this paper， the effects of alkali-activated cementitious material content and alkali content on the properties of solidified soil under dry-wet cycle were clarified by 15 dry-wet cycle tests and multi-parameter analysis such as mass loss rate， unconfined compressive strength， pH value， conductivity and SEM characterization. The results show that when the content of cementitious material is 40% （mass fraction） and the alkali content is 5.0% （mass fraction）， after 15 dry-wet cycles， the mass loss rate is 1.9%， the unconfined compressive strength retention rate is 74.2%， and the appearance of solidified soil samples is smooth and crack-free. The results of this study can provide reference for the application of alkali-activated cementitious material solidified silty clay in road engineering.

Durability Evaluation of Cement Stabilized Gravel Base with Iron Tailings Sand in Cold Regions

GAO Feng, YANG Zhuohang, HAN Chang, WEN Penghui

2026, 45(5):  1812-1822.  doi:10.16552/j.cnki.issn1001-1625.2025.1080

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To improve the large-scale resource utilization level of iron tailings sand in road construction projects in severe cold mining areas， iron tailings sand was used to partially replace fine aggregates in preparing iron tailings sand cement stabilized gravel. The influence of iron tailings sand content on compaction parameters and unconfined compressive strength was investigated. The drying shrinkage characteristics， thermal shrinkage characteristics， frost resistance， and fatigue performance of cement stabilized gravel base under different preparation conditions were systematically studied. The results indicate that sodium silicate modification of iron tailings sand enhances its interfacial adhesion with cement paste， thereby improving the road performance of cement-stabilized gravel bases. As the iron tailings sand content increases， the maximum dry density of the cement-stabilized gravel increases first and then decreases. When the dosage of iron tailings sand is 60% （mass fraction）， the unconfined compressive strength reaches its maximum. Reducing cement content and modifying the surface of iron tailings sand both improve the durability of cement stabilized gravel. Compared with the sample mixed with unmodified iron tailings sand， the dry shrinkage coefficients of cement-stabilized gravel modified with iron tailings sand at a cement content of 4.0%（mass fraction） decrease by 24.31% and 17.74% at 7 and 14 d， respectively. When the temperature is reduced to 10~<20 ℃， the thermal shrinkage coefficient of cement stabilized gravel base samples with modified iron tailings sand reaches its minimum value. When the cement content is 4.0%， the improvement in frost resistance of cement stabilized gravel is more pronounced. The addition and modification of iron tailings sand can prolong the fatigue life of cement stabilized gravel， with the fatigue life improvement reaching up to 86.43%. The introduction of iron tailings sand in cold and arid mining areas can improve the service durability of cement stabilized gravel. The optimal replacement ratio of fine aggregates with modified iron tailings sand is recommended as 60%.

Shrinkage Compensation Mechanism and Properties of Dense-Skeleton Cement-Stabilized Crushed Stone-Steel Slag Mixture

LI You, WANG Xueqi, ZHAO Yuxia, ZHENG Mulian, HUANG Jie, LU Chuan, LI Yifeng

2026, 45(5):  1823-1837.  doi:10.16552/j.cnki.issn1001-1625.2025.1016

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To elucidate the shrinkage compensation mechanism of cement-stabilized crushed stone-steel slag， this study investigated the unconfined compressive strength， compressive resilience modulus， tensile splitting strength， and bending strength of dense-skeleton cement-stabilized crushed stone-steel slag with varying steel slag and cement content. Based on the expansion characteristics of steel slag and utilizing XRD and SEM techniques， the dry shrinkage strain， thermal shrinkage coefficient， and total shrinkage rate were evaluated. Additionally， the frost resistance， erosion resistance， and fatigue resistance of the mixtures were assessed. The results indicate that as the steel slag content increases， the mechanical properties of the cement-stabilized crushed stone-steel slag material increase. And the dry shrinkage strain of the materials with 20% and 40% （volume fraction） steel slag content decreases by 8.9% and 16.7%， respectively， but the temperature shrinkage coefficient increases by 2.6% and 6.4%. Nevertheless， steel slag incorporation generally contributes to reducing the total shrinkage rate of the material by 19.2% and 26.6%， respectively. The hydration of free calcium oxide in steel slag is the primary cause of volume expansion and its ability to compensate for the shrinkage of cement-stabilized crushed stone materials. The durability of the materials is enhanced by the incorporation of steel slag， with residual strengths after 6 freeze-thaw cycles increasing by 2.0% and 3.8% at 20% and 40% slag content， respectively， mass loss rates after 300 cycles of erosion decreasing by 22.2% and 38.2%， respectively， while fatigue life at a stress level of 0.80 improving by 88.32% and 230.00%， respectively. Furthermore， cement content significantly impacts the road performance characteristics of cement-stabilized crushed stone-steel slag materials. Increasing cement content markedly enhances the mechanical properties and durability of the material but adversely affects its shrinkage crack resistance.

Influence and Mechanism of Micro-Nano Bubble Water on Physical and Mechanical Properties of Cement-Stabilized Crushed Stone

XIE Xiangbing, JIA Yapeng, LI Cheng, HOU Boyan, ZHANG Yanxiang, WAN Zhenmin, SHAO Jinggan

2026, 45(5):  1838-1850.  doi:10.16552/j.cnki.issn1001-1625.2025.0990

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Micro-nano bubble water （MNBW）， as an active mixing water with a high specific surface area and strong molecular activation capability， which can effectively promote the early-age hydration process of cement-based materials. In this study， MNBW was introduced into cement-stabilized crushed stone mixtures.Through compaction tests， physical and mechanical properties as well as the microstructure of cement-stabilized crushed stone were systematically investigated through compaction tests， physical and mechanical properties tests， and microstructural analyses （XRD， FTIR， and SEM）. The results indicate that compared with ordinary mixing water， the mixture prepared with MNBW exhibits a slightly increased maximum dry density and a reduced optimum moisture content， thereby improving its compaction characteristics. MNBW-mixed specimens exhibit higher unconfined compressive strength， splitting strength， and flexural tensile strength at different curing ages， with the most pronounced enhancement observed at early ages. In addition， the incorporation of MNBW effectively reduces the water absorption rate of cement-stabilized crushed stone， indicating an improvement in the internal pore structure of the material. Microstructural analyses show that MNBW promotes the formation of hydration products such as calcium silicate hydrate （C-S-H） gel and calcium hydroxide （CH）， resulting in a denser internal structure of specimens.