Table of Content

Volume 45 Issue 6
15 June 2026

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Cement and Concrete

Research Progress of CO₂ Curing for Calcium Silicate Board

YE Junhao, CHEN Ge, FANG Jingrui, BAI Feng, QIN Hesheng, WANG Lina

2026, 45(6):  1851-1863.  doi:10.16552/j.cnki.issn1001-1625.2025.1248

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The autoclaved curing process， a mainstream step in calcium silicate board production， is characterized by high energy consumption and a significant proportion of carbon emissions. Meanwhile， CO₂ curing technology offers a dual advantage： it simultaneously enhances the interfacial properties of calcium silicate-based materials and enables CO₂ sequestration. However， the lack of a systematic summary of this technology’s application in the calcium silicate board field currently hinders its process optimization and engineering promotion. This work provides a systematic review of the research progress of CO₂-cured calcium silicate boards. It begins by outlining the key steps of the autoclaved curing process and the common defects in the resulting products. It then elucidates the carbonation process of calcium silicate minerals during CO₂ curing， along with the characteristics of the reaction products and the multi-scale mechanisms involved. Building on this foundation， the performance of CO₂-cured boards is compared with that of autoclave-cured boards in terms of mechanical properties and CO₂ sequestration efficiency， analyzing the technology's advantages and limitations. Finally， future research directions are proposed， including the synergistic optimization of process parameters and the targeted regulation of carbonation mechanisms at the fiber-matrix interface. The study indicates that CO₂ curing enhances material performance through pore filling by products and interface strengthening， while achieving stable CO₂ sequestration. Nevertheless， challenges such as low curing efficiency and insufficient long-term stability still exist. This review can provide theoretical reference and practical basis for the green manufacturing upgrade of calcium silicate boards and decarbonization pathways of the construction materials industry.

Influences of Multiple Components on Performance Deterioration of Magnesium Potassium Phosphate Cement under High-Temperature

ZHOU Zheng, ZHOU Yutong, ZHAO Zhoufeng, QIU Lyuchao, ZHANG Shiyuan, WANG Liting, PENG Bo, JIAN Shouwei, TAN Hongbo

2026, 45(6):  1864-1875.  doi:10.16552/j.cnki.issn1001-1625.2025.1276

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Magnesium potassium phosphate cement （MKPC） is prone to dehydration and decomposition of its hydration products under high-temperature exposure， which leads to strength degradation and volumetric shrinkage， thereby limiting its engineering applications in high-temperature environments. To address this issue， an orthogonal experimental design was employed to systematically investigate the effects of the water-to-binder ratio and the content of silica sol， expanded vermiculite， and glass beads on the performance degradation of MKPC under high-temperature. The underlying mechanisms were further elucidated through microstructural analyses using XRD， SEM， and TG-DSC. The results indicate that expanded vermiculite and glass beads can effectively mitigate strength loss and volumetric shrinkage under high-temperature conditions and are the key components for suppressing the performance degradation of MKPC under high-temperature. When the water-binder ratio is 0.25 and the dosages of silica sol， expanded vermiculite and glass beads are 5%， 15% and 12% （mass fractions）， respectively， MKPC exhibits excellent strength stability and volume stability at high temperatures. Microstructural analyses reveal that expanded vermiculite promotes the formation of refractory silicate phases to construct a stable high-temperature skeleton， while glass beads soften to form a glassy phase that enhances particle bonding. The synergistic effect of these two components effectively improves the high-temperature structural stability of MKPC from both phase composition and microstructural perspectives.

Influence of Freeze-Thaw Cycles on Mechanical and Water Absorption Properties of Silane-Modified ECC

LIU Yajun, XUE Shanbin, ZHENG Zihao, SHI Zhihao, WANG Wenhuan

2026, 45(6):  1876-1891.  doi:10.16552/j.cnki.issn1001-1625.2025.1154

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This study comprehensively investigated the influence patterns and mechanisms of internally incorporated silane types on the mechanical properties and water absorption properties of engineered cementitious composites （ECC） using multiple material testing techniques. It analyzed the evolution patterns and microscopic mechanisms of mechanical and water absorption properties for both unmodified ECC and isooctyl triethoxy silane IOTS modified ECC after freeze-thaw cycles. The results show that： except for γ-methacryloxy propyl trimethoxy silane （KH570）， neither IOTS nor N-（β-aminoethyl）-γ-aminopropyl trimethoxy silane （KH792） causes a significant negative impact on the mechanical properties of ECC. Both KH570 and KH792 markedly delay the hydration heat release of the cementitious materials. The IOTS modified ECC exhibited the best hydrophobicity， maintaining its hydrophobic characteristics even after severe freeze-thaw damage. After freeze-thaw cycles， the compressive strength deterioration rate of IOTS-modified specimens is higher than that of unmodified specimens， but their flexural strength remains higher. As the number of freeze-thaw cycles increases， the relationship between the water absorption mass per unit area and the square root of time shifts from linear to bilinear for both types of specimens， and the duration of the initial linear stage shortens as the number of freeze-thaw cycles increases. The research findings provide a theoretical basis for the hydrophobic design of ECC and its application and durability evaluation in freeze-thaw environments.

Influence of Low-Concentration CO₂ Environment at 40 ℃ on Early Carbonation and Hydration Reaction Process of Cement Mortar

HU Qinghao, LI Shaochun, CHEN Xu, ZHANG Shuchang

2026, 45(6):  1892-1902.  doi:10.16552/j.cnki.issn1001-1625.2025.1148

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In response to the low-carbon development strategy for building materials， this study explores the optimization path for early-age performance of cement-based materials under low-concentration CO₂ conditions. Cement mortars were subjected to CO₂ curing at 3% （volume fraction） concentration and 40 ℃ for 2， 6， and 12 h to investigate the effects of the carbonation-hydration synergy on mechanical properties， microstructure evolution. The results show that the comprehensive performance of cement-based materials is optimal after 6 h of carbonation， with a 28 d compressive strength of 58.6 MPa—approximately 15.1% higher than that of the purely hydrated sample. At this stage， the amount and crystallinity of CaCO₃ reach their maximum， and the proportion of calcite increases significantly. Mercury intrusion porosimetry results reveal that 6 h carbonation effectively refines the pore structure of the specimen surface layer， reducing porosity to 21.8% and enhancing compactness and stability of the material. However， extending the carbonation time causes deterioration of the surface pore structure， leading to reduce strength due to over-carbonation.

Hydrophobic Properties and Mechanism of TEOS-IBT Synergistically Modified Cement Paste

CHENG Zigao, CONG Yun, ZHANG Yan, LI Gen, ZHI Tianyi, TAN Hongbo

2026, 45(6):  1903-1913.  doi:10.16552/j.cnki.issn1001-1625.2025.1160

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To improve the hydrophobic properties of cement-based materials， isobutyl triethoxysilane （IBT） and tetraethyl orthosilicate （TEOS） were used to singly and jointly modify P·I 52.5 Portland cement paste （water-cement ratio of 0.35）. The content of IBT or TEOS was set to 1%~6% （mass fraction）， and 1%~3% TEOS was compounded on the basis of fixing the IBT content at 3% （mass fraction）. The cement paste was characterized by tests of fluidity， setting time， compressive strength， contact angle， capillary water absorption coefficient （S）， heat of hydration， combined with characterization techniques such as SEM、FTIR and XRD. The results show that the co-admixture markedly amplifies surface hydrophobicity， the compound addition of IBT-3%+TEOS-3% increases the contact angle up to 140.0°， compared with the single addition of 3% IBT， the contact angle is increased by 58.37%. In terms of moisture transport performance， IBT-4% reduces capillary water absorption coefficient （S） from the control value of 0.004 19 mm·s^-1/2 to 0.000 99 mm·s^-1/2； When TEOS of 1%~3% is compounded on the basis of fixing the IBT content at 3%， S is 0.002 93~0.003 63 mm·s^-1/2， higher than IBT-3% alone group but still 13%~30% lower than the control. Based on the above results， this study reveals the synergistic mechanism of TEOS and internally mixed IBT in modified cement paste， and provides an operable basis for the design of hydrophobic cement-based materials.

Mechanical Anisotropy and Pore Evolution Mechanism of 3D Printed Concrete

MA Lianxia, LIU Chao, CHEN Wei, ZHU Wenxuan, ZHAO Weifei, YANG Qiuju

2026, 45(6):  1914-1923.  doi:10.16552/j.cnki.issn1001-1625.2025.1282

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3D printed concrete （3DPC） faces challenges regarding anisotropy and interlayer weakness， which limit its structural applications. This study investigated the intrinsic correlations between buildability， mechanical behavior， and pore structure of 3DPC through macro-micro scale analysis. Firstly， a material system suitable for extrusion was designed. Furthermore， X-ray computed tomography （X-CT） and digital image correlation （DIC） were employed to quantitatively analyze pore characteristics and their influence on damage evolution. The results show that 3DPC has excellent thixotropy and buildability， and achieves 19 layers of continuous stacking without collapse in ultimate buildability tests. DIC analysis reveals significant anisotropy in crack evolution： X-direction loading causes cracks to propagate upwards and downwards from the edges， Y-direction loading shows bottom-up propagation， while Z-direction loading induces 45° shear failure along the interlayer interface. Microscopic analysis confirms that the complex irregular pores and interlayer interfaces within 3DPC are the sources of crack initiation. This study not only validates the printing performance of the material but also provides a basis for revealing the damage mechanism and achieving crack precise control in 3DPC.

Optimization Design and Performance Study of Shotcrete Mix Proportion for Tunnels in High-Altitude Mountainous Regions

LI Yue, ZHOU Guanghui, YANG Bin, JIN Kaikai, JIANG Zezhou, QIU Ziheng, SHAO Weiwei

2026, 45(6):  1924-1936.  doi:10.16552/j.cnki.issn1001-1625.2025.1281

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To prepare shotcrete suitable for high-altitude mountainous regions， this study employed orthogonal experimental design to investigate the effects of early-strength admixture dosage， water-binder ratio， accelerator dosage， and sand ratio on the slump， 8 h compressive strength， and 28 d compressive strength of shotcrete. The results show that the early-strength admixture dosage and water-binder ratio significantly affect the shotcrete’s flowability and compressive strength. The sand ratio influences flowability as well as early and late compressive strength， though to a lesser extent. The accelerator dosage has a minor effect on both early and late compressive strength. Secondly， through range analysis and grey target decision theory， an optimal mix proportion design for shotcrete is obtained： early-strength admixture dosage of 26% （mass fraction）， water-binder ratio of 0.30， accelerator dosage of 7% （mass fraction）， and sand ratio of 50%. Finally， XRD， TG， and SEM microstructural analyses elucidate the mechanisms by which the accelerator and early-strength admixture influence shotcrete performance， the two exhibit a synergistic effect， significantly enhancing the early strength of the cement paste. These findings provide technical support for the optimized design and preparation of shotcrete for tunnels in high-altitude and rugged mountainous regions.

Experimental Study on Mechanical Properties of UHPC Based on SHPB and Direct Shear Apparatus

YANG Heng, LI Mengmeng, CHEN Jiangying

2026, 45(6):  1937-1946.  doi:10.16552/j.cnki.issn1001-1625.2025.1156

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In practical engineering， concrete structural members are subjected not only to compressive loads but also frequently to tensile and shear loads. Therefore， investigating the mechanical behavior of ultra-high performance concrete （UHPC） under various stress states and loading rates is crucial for structural safety design. In this study， quasi-static and dynamic compression， splitting tensile， and shear tests were performed on UHPC with and without steel fibers， utilizing a universal testing machine， a split Hopkinson pressure bar （SHPB）， and a self-designed direct shear apparatus. The results indicate that the incorporation of steel fibers significantly enhances the mechanical properties of UHPC under both quasi-static and dynamic conditions. Furthermore， both types of specimens （UHPC with and without steel fibers） exhibit a significant strain rate hardening effect. Specifically， in the shear tests， although the presence of steel fibers and high strain rates alter the evolution characteristics of peak stress， they do not alter the failure mode， which remains as mixture fractures of type I and type II.

Effect of Nano AFt on Properties of Supersulfated Cement-Based Foam Concrete

ZHAO Hui, YAN Wei, JIA Shaozhen, LIU Yakun, WANG Lei, MENG Jiang, WANG Jun, ZHANG Miao

2026, 45(6):  1947-1958.  doi:10.16552/j.cnki.issn1001-1625.2025.1128

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Supersulfated cement-based foamed concrete （SSC-FC） has broad application potential in the field of building energy conservation due to its lower carbon emissions and cost. However， its slow early hydration and insufficient formation of hydration products of SSC-FC result in poor pore-wall compactness， leading to inadequate mechanical properties and carbonation resistance， which significantly limit its engineering applications. In this study， nano ettringite （nano AFt） was incorporated to enhance the pore-wall structure of SSC-FC through its nucleation-induced effect. The influence of nano AFt content on the mechanical properties and carbonation resistance of SSC-FC was systematically investigated， and the mechanisms on hydration process， phase composition， and pore-structure evolution were analyzed using isothermal calorimetry， XRD， SEM. The results show that the incorporation of nano AFt accelerates early hydration and promotes the formation of AFt at the pore-wall interface， leading to a denser pore-wall structure. When the nano AFt content reaches 8%（mass fraction）， the 7 d compressive strength of SSC-FC increases from 1.26 MPa to 2.08 MPa， and the 28 d compressive strength increases from 2.37 MPa to 3.61 MPa. In addition， nano AFt refines the pore size distribution， reduces the pore coordination number， and decreases the number of connected pores， thereby restricting CO₂ transport. Under 1 d accelerated carbonation conditions， the sample with 8% nano AFt retains an uncarbonated region of 25 mm， and its carbonation coefficient increases from 0.88 to 0.92.

Regulation and Stability of Ettringite Growth by Aluminum Phases

TANG Pei, ZHAO Dongsheng, CHEN Wei

2026, 45(6):  1959-1967.  doi:10.16552/j.cnki.issn1001-1625.2025.1246

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Ettringite is the main hydration product of sulfate-based low-carbon cementitious materials and has a significant impact on the mechanical properties and durability of the materials. It is crucial to explore the formation and evolution process of ettringite. Aluminum phase is often used as a key component to regulate the growth of ettringite. Existing studies mostly focus on the improvement of the macroscopic performance of low-carbon cementitious materials by adding external aluminum phase， while the formation mechanism of ettringite by it still needs to be further improved. This paper synthesized ettringite using four types of aluminum phases， namely， crystalline aluminum chloride （AC）， aluminum sulfate octadecahydrate （AS）， polymeric aluminum sulfate （PAS）， and sodium aluminate （NA）， as raw materials， and investigated the influence of the type of aluminum phase on the growth behavior and stability of the synthesized ettringite. The results show that 60 ℃ is the optimal synthesis temperature for ettringite formation， and the mass fraction of ettringite formed with AS participation is the highest， reaching 94.23%. Compared with other aluminum phases， the maximum weight loss temperature of ettringite formed with AS participation is 120.4 ℃， with the best thermal stability， more stable crystal structure， and a smaller variation in the aspect ratio， which is around 14.5. This study provides a theoretical foundation for the subsequent optimization design and performance improvement of low-carbon cementitious material systems.

Stability of Calcium Carboaluminate Prepared by One-Step Method Under Various Environmental Conditions

WANG Yingxiang, DING Tianhui, JI Zhijiang, XIE Shuai, WU Zihao, MA Chao, YU Haiyan

2026, 45(6):  1968-1978.  doi:10.16552/j.cnki.issn1001-1625.2025.1237

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This study used a one-step method to prepare calcium carboaluminate （MC）， which involved the direct reaction of calcium sources， aluminum sources， and carbonate sources at temperatures of 80， 90， and 100 ℃. The stability of the prepared MC in solutions with different pH levels， temperatures， and concenrations of chloride salt， sulfate， and its mixed salt environments was investigated using X-ray diffraction， scanning electron microscopy， and thermogravimetric analysis. The results indicate that MC prepared via the one-step method exhibits excellent chemical stability in alkaline environments （pH≥11）. The initial decomposition temperature of MC is 130 ℃， and it completely decomposes into CaO and Al（OH）₃ at 450 ℃. In chloride solutions， MC readily immobilizes free Cl^- to form Friedel’s salt. The immobilization efficiency shows a positive correlation with the Cl^- concentration， and MC prepared at 90 ℃ demonstrates the highest Cl^- reactivity. In sulfate solutions， MC easily reacts with \mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} to form ettringite. In CaCl₂-Na₂SO₄ mixed salt solution， \mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{\mathrm{2}-} has a higher reaction priority than Cl^-. At a low concentration （0.2 mol/L） of the mixed salt solution， the main products are ettringite and calcium carbonate， while at high concentrations （0.5 and 1.0 mol/L）， the products shift predominantly toward calcium sulfate dihydrate phases. This study provides new insights and experimental support for the feasibility of using one-step MC as a corrosion inhibitor for steel reinforcement in practical engineering， confirming that its stability is closely related to the synthesis temperature， as well as the type and concentration of environmental ions.

Solid Waste and Eco-Materials

Effect of Activation Process on Properties of Kaolin-Based Low-Carbon Cement

LIAO Yuntian, PENG Wenjie, LI Bo, CHEN Wei, ZHENG Xuhang

2026, 45(6):  1979-1987.  doi:10.16552/j.cnki.issn1001-1625.2025.1116

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This study utilized activated kaolin， limestone powder， and a small amount of cement clinker to prepare low-carbon cement. The effects of two activation methods， mechanochemical activation and thermal activation on the microstructure of kaolin， the properties of the low-carbon cement， and the composition and structure of its hydration products were systematically examined. The results indicate that kaolin transforms into an amorphous state after activation treatment. Mechanochemical activation is more effective in enhancing the reactivity of kaolin than thermal activation. When 40% （mass fraction） mechanochemically activated kaolin and 20% （mass fraction） limestone powder are incorporated， together with an external addition of 5% by mass of calcium hydroxide， the prepared low-carbon cement achieves compressive strengths of 14.8 MPa at 3 d and 39.4 MPa at 28 d. The main hydration products are calcium silicate hydrate （C-S-H） gel， ettringite （AFt） ， and calcium sulfoaluminate hydrate （AFm）. Furthermore， the external addition of calcium hydroxide enhances the pozzolanic reaction of kaolin， increases the formation of hydration products， and improves pore structure of the paste and enhances its mechanical properties. This study explores a technical pathway for producing low-carbon cement with activated kaolin， achieving favorable performance development at a 60% clinker replacement rate by mass， thereby providing an effective approach for the development of low-carbon cement.

Preparation and Performance Prediction of Multi-Component Blended Green ECC Based on Orthogonal Experiment

ZHAO Tianpu, ZHAN Xuefang, LIU Xiaojun, HUANG Dan, ZHAO Yibin, WANG Haolei

2026, 45(6):  1988-2001.  doi:10.16552/j.cnki.issn1001-1625.2025.1245

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To reduce cement consumption， promote solid waste utilization， and enhance both the strength and ductility of engineered cementitious composites （ECC）， this study investigated the effects of partially replacing cement with a ternary blend of rice husk ash （RHA）， rice straw ash （RSA）， and corn straw ash （CSA） on the static mechanical properties of ECC. Based on the principles of orthogonal experimental design， 9 groups of multi-component blended green ECC mixtures were designed. Uniaxial tensile， cubic compressive， and four-point bending tests were conducted to analyze the influences of RHA， RSA， and CSA at different replacement ratios （0%， 5%， and 10%， mass fraction） on various mechanical performance indicators of ECC. Furthermore， a predictive model for the static mechanical properties of the ternary-blended green ECC was established. Results indicate that the mixture containing 5% RHA and 5% CSA exhibits the best mechanical performance， compared with the control. Its 28 d tensile strength， ultimate tensile strain， and flexural load capacity increase by 15.31%， 46.64%， and 24.45%， respectively. RHA was the dominant factor influencing tensile behavior， while CSA mainly affects compressive and flexural strength； the influence of RSA is minimal. Regression models developed for compressive strength and tensile strain showed good accuracy， providing theoretical support for utilizing agricultural waste ashes in green ECC.

Influence of Limestone Powder on Properties of Sulphoaluminate Cement-Based Grouting Material

ZHAO Feifei, ZHANG Haibo, CHAI Hucheng

2026, 45(6):  2002-2010.  doi:10.16552/j.cnki.issn1001-1625.2025.1164

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To address the issues of rapid heat release， unstable setting and hardening time， and relatively high cost in sulfoaluminate cement-based grouting material （SCGM）， and to further promote the resource utilization of manufactured sand stone powder and the development of green building materials， this study investigated the effect of stone powder on the fluidity， bleeding rate， setting time， and compressive strength of SCGM. The underlying mechanism of stone powder on the workability of SCGM was explored using micro-testing techniques such as XRD， SEM， TG-DTG， and NMR. The results indicate that stone powder promotes the hydration of SCGM， enhances its 28 d mechanical properties， and fills material voids. When the stone powder content is 5%（mass fraction）， compared with the reference sample without stone powder， the 3 d compressive strength of SCGM decreases by 11.4%， while the 28 d compressive strength increases by 10.5%， and the porosity decreases by 10.3%. Additionally， stone powder improves the fluidity of SCGM and extends its setting time.

Prediction Model for Autogenous Shrinkage of Concrete with Combined Incorporation of Fly Ash and Ground Granulated Blast-Furnace Slag Powder

GU Shengbin, LI Beixing, WENG Xianjie, TIAN Shenhua

2026, 45(6):  2011-2020.  doi:10.16552/j.cnki.issn1001-1625.2025.1238

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To accurately predict the influence of combined incorporation of fly ash （FA） and ground granulated blast-furnace slag powder （GGBS） on the early-age autogenous shrinkage behavior of concrete， this study systematically investigated the development of autogenous shrinkage in 16 concrete mixtures with total replacement levels of 20%， 30%， 40%， and 50% （mass fraction） by FA and GGBS， and FA-to-GGBS blending ratios of 3∶0， 3∶1， 3∶2， and 3∶3 （mass ratio）. Based on the experimental results， a corresponding prediction model for autogenous shrinkage was established. The results indicate that when the FA-to-GGBS blending ratio is fixed， the autogenous shrinkage rate of concrete decreases with the increase in the total replacement level of mineral admixtures. Conversely， with a constant total replacement level， the autogenous shrinkage increases significantly as the proportion of GGBS rises. Grey relational analysis further reveals that the FA content is the dominant factor influencing autogenous shrinkage， with a greater impact than GGBS. Building on these findings， this study modifies the classical B4 model for concrete autogenous shrinkage by introducing a correction term K_fs to characterize the effect of combined incorporation of FA and GGBS and adopting a time-development exponent n_fs related to the ultimate autogenous shrinkage. Thus， a prediction model suitable for concrete incorporating both FA and GGBS is established. Validation results demonstrate that the model predictions agree well with experimental data， providing a theoretical basis for predicting autogenous shrinkage in related engineering applications.

Performance and Mechanism of Wollastonite-Slag-Metakaolin Geopolymer under Seawater Wet-Dry Cycles

WANG Xiaobin, LUO Liting, HE Zixiang, CHEN Juan

2026, 45(6):  2021-2033.  doi:10.16552/j.cnki.issn1001-1625.2025.1224

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To investigate the service performance of metakaolin geopolymer mortar in marine environments， this study focused on the degradation behavior and mechanisms of metakaolin geopolymer mortar modified with a wollastonite-slag composite admixture under two erosion modes： seawater wet-dry cycles and full immersion. Wollastonite-slag-metakaolin geopolymer mortars （WSM） with varying mass ratios of wollastonite to slag （1∶2， 1∶1， and 2∶1）， along with pure metakaolin mortar （MK）， were prepared. The evolution of their apparent morphology， physical properties， and mechanical performance over 0~90 erosion cycles was comparatively investigated， and the degradation mechanisms were analyzed using micro-testing methods such as SEM and XRD. The results indicate that the damage caused by wet-dry cycles is significantly more severe than that by full immersion. The former is identified as a “physical-chemical” coupled erosion process driven by salt crystallization pressure and an ion “pump” effect. The wollastonite-slag composite admixture significantly enhances erosion resistance and durability of metakaolin geopolymer mortar. Specifically， when the mass ratio of wollastonite to slag is 1∶1 （WSM15）， geopolymer mortar exhibits the optimal performance. Compared with the reference MK group， the compressive strength of WSM15 increases by 59.3%， while the mass loss rate is reduced by 30.97%. The enhanced performance originates from the physical and chemical synergistic effects of wollastonite and slag.

Influences of Composite Mineral Admixtures on Strength and Capillary Water Absorption of Thermal Wet Curing Cement Mortar

HU Cheng, WANG Qijie, XIANG Weiheng, LIANG Yuyuan, CAO Kang, CAI Guangrun

2026, 45(6):  2034-2040.  doi:10.16552/j.cnki.issn1001-1625.2025.1262

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In order to drive the green and low-carbon transformation of the building materials industry， the steel slag （SS）， ground granulated blast furnace slag （GGBS） and fly ash （FA） were used to replace 40% （in mass， the same below） of cement， and systematically studied the effects of different mix designs on the mechanical properties，capillary water absorption characteristics and microscopic properties of composite cementitious materials under thermal wet curing. The test results show that in terms of mechanical properties， when the content of FA is 10%， the flexural and compressive strength of mortar specimen are higher than those of 0% and 20% FA. At the same time， with the increase of SS content and the decrease of GGBS content， the flexural and compressive strength of mortar specimen also decrease. In addition， when the SS content is 10% and GGBS content is 20%， the flexural strength and compressive strength are second only to the group with SS content of 0% and GGBS content of 30%， The increase in flexural strength is similar for both， while the increase in compressive strength is higher for the former than for the latter. In terms of capillary water absorption characteristics， with the increase of SS content， the capillary water absorption coefficient also increases gradually， reflecting the deterioration of pore structure. In terms of microscopic properties， the increase of SS content will reduce the active components of composite cementitious materials， but the appropriate amount of SS can promote the hydration reaction of GGBS.

Mechanical Properties and Shrinkage Properties of Multi-Component Composite Solid Waste Cementitious Materials

CHENG Kunyang, LIU Xiaolin, FENG Yuan, WANG Yanpeng, ZHANG Rui, YU Bentian

2026, 45(6):  2041-2051.  doi:10.16552/j.cnki.issn1001-1625.2025.1217

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To promote the efficient recycling of industrial solid waste and reduce carbon emissions of cement-based materials， this paper utilized tuff powder， fly ash， slag powder， and silica fume to synergistically replace part of cement， preparing a novel multi-component composite solid-waste cementitious material. Four groups of high-activity mix proportion were optimized through pozzolanic activity and strength index tests. Their fluidity， early and late strength （compressive/flexural strength）， autogenous shrinkage， and drying shrinkage performance were systematically tested. Combined with nuclear magnetic resonance （NMR）， X-ray diffraction （XRD）， and scanning electron microscopy （SEM） techniques， the micro-evolution mechanisms of the materials were deeply analyzed.Tests indicate that the introduction of multi-component solid wastes， while causing a slight reduction in early strength， significantly improves early autogenous shrinkage （reduced by 18.3% to 29.7%）. However， due to the increase of free water evaporation caused by the delay of early hydration process， the drying shrinkage of the system increases （increased by 44.0% to 58.3%）.Microscopic analysis reveals that the incorporation of solid waste dilutes clinker concentration in the early stage and retards reaction rates， which is conducive to reducing autogenous shrinkage. However， in drying environments， slower hydration leads to increased free water loss， thereby increasing drying shrinkage. With the extension of curing age， multi-component solid wastes participate in secondary hydration. The generated gel products fill internal defects and significantly increase the proportion of harmless and less harmful pores， thereby optimizing the overall pore structure.

Hydration and Hardening Mechanism and Property Optimization of SS-GBFS-Cement-DG Quaternary Cementitious System

WU Yankun, CHEN Jian, HAO Jianshuai, FANG Kuizhen

2026, 45(6):  2052-2062.  doi:10.16552/j.cnki.issn1001-1625.2025.1110

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To achieve the high-value resource utilization of bulk industrial solid wastes， this study constructed a quaternary cementitious system centered on the synergy between steel slag （SS） and granulated blast furnace slag （GBFS）， activated by cement and desulfurization gypsum （DG）. The synergistic hydration mechanism of the quaternary cementitious system under composite activation was revealed through systematic mixture proportion design and micro-characterization techniques such as mercury intrusion porosimetry （MIP） and scanning electron microscopy （SEM）. The interwoven formation of hydration products ettringite （AFt） and calcium silicate hydrate （C-S-H） gel continuously consumed Ca（OH）₂， thereby driving significant pore refinement and microstructural densification， was elucidated. The optimal mass fractions for each key component is 40% GBFS， 10% cement， and 8%~12% DG. Hydration kinetics analysis indicates that the system exhibits typical three-stage exothermic characteristics： aluminate phase reaction， silicate hydration of cement， and a pronounced secondary reaction stage attributable to the alkaline-sulfate activation of GBFS. The sulfate from DG and alkalinity from cement jointly activated the GBFS and SS， promoting continuous formation of AFt and C-S-H gel while extensively consuming Ca（OH）₂. MIP and SEM results further demonstrate significant microstructural densification of the quaternary cementitious system at 28 d： the proportion of harmful pores （>50 nm） decreases markedly， while that of harmless gel pores （<50 nm） increases from 68% to 81%. The C-S-H gel develops from an interlaced distribution into a continuous honeycomb-like structure， tightly interwoven with AFt crystals to form a dense network. This research clarifies the underlying strength development mechanism of the quaternary binder system， driven by synergistic activation and pore structure refinement. It offers a theoretical foundation and technical route for the development of high-performance， low-carbon construction materials.

Influence of Carbonized Recycled Cement Concrete Powder on Performance of Foamed Concrete

HE Yanhui, WANG Huan, ZOU Yong, CHEN Cheng, XU Peng, HE Zhihao

2026, 45(6):  2063-2074.  doi:10.16552/j.cnki.issn1001-1625.2025.1151

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Under the background of the “double carbon” target， the high energy consumption and high emission problems of the cement industry need to be solved urgently. The resource utilization of construction solid waste has become an important way for the development of low-carbon building materials. In this study， ordinary Portland cement was used as the matrix， and recycled cement concrete powder （RCCP） and carbonated recycled cement concrete powder （carbonated RCCP） were prepared by accelerated carbonation treatment. Foamed concrete was prepared by replacing cement with 0%， 20%， 40% and 60% （mass fraction） RCCP and carbonated RCCP respectively. The effect of carbonated RCCP on the workability， microstructure and thermal properties of foamed concrete was analyzed by fluidity， dry density， water absorption rate， compressive strength， XRD， TG-DSC， SEM， microCT and thermal conductivity coefficient tests. The results show that with the increase of RCCP substitution rate， the fluidity of slurry decreases. When the substitution rate is 60%， the fluidity of carbonated and uncarbonated samples decreases by about 8.0% and 11.0% respectively compared with the reference sample. With the increase of the substitution rate of carbonated RCCP， the compressive strength of sample increases first and then decreases. When the substitution rate is 20%， the 28 d compressive strength reaches the peak value， which is 6.3% higher than that of RCCP sample. With the increase of RCCP substitution rate， the porosity increases， the thermal conductivity performance is improved. When the substitution rate of carbonated RCCP is 60%， the thermal conductivity is 6.8% lower than that of RCCP sample.

Ceramics

Research Progress on Biomass-Based High-Performance Structural Carbon Materials: Carbon Fibers, Carbon (Carbide) Matrices, and Carbon Coatings

LI Chuxing, WANG Honglei, ZHOU Xingui, YU Jinshan

2026, 45(6):  2075-2091.  doi:10.16552/j.cnki.issn1001-1625.2025.1088

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Carbon materials play a key role in promoting the development of human civilization， but their preparation depends on fossil raw materials and faces severe challenges such as resource shortage and environmental pollution. Biomass has become an ideal carbon source to replace fossil raw materials due to its wide range of sources， renewable and carbon neutrality. The existing reviews in the field of biomass carbon pay more attention to functional carbon materials with high specific surface area. This paper focuses on high-performance structural carbon materials and systematically reviews its latest research progress， including the following three directions. Aiming at the problem of insufficient mechanical properties of biomass carbon fibers， optimization strategies are proposed from two aspects： raw material screening and precursor modification. The preparation and properties studies of carbon matrix and carbide ultra-high temperature ceramic matrix based on sugar sol-gel process are reviewed， and the advantages and existing challenges of sugar sol-gel process are discussed. The formation mechanism， quality control strategy of carbon coating prepared by carbohydrate hydrothermal carbonization technology and its influence on the mechanical properties of composites as interface phase are described.

Research Progress on Tunable Properties of Barium Strontium Titanate Ceramics

ZHAO Yi, RAN Dongsheng, JIN Yihang, XIA Chenyu, CHENG Lu, LIU Wenfeng

2026, 45(6):  2092-2103.  doi:10.16552/j.cnki.issn1001-1625.2025.1222

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Barium strontium titanate （Ba_1-x Sr _x TiO₃，BST） ceramics， as an environmentally friendly ferroelectric material， have attracted considerable attention among lead-free dielectric tunable materials due to their excellent dielectric properties， large dielectric nonlinearity， good chemical stability， and adjustable Curie temperature. Owing to simple preparation processes and relatively low production costs， BST ceramics exhibit wide application prospects in modern communication systems， electronic information equipment， and tunable microwave devices. In recent years， extensive research on the enhancement of tunable properties and comprehensive improvement of dielectric characteristics in BST ceramics has been carried out， aiming to meet the requirements of next-generation tunable microwave devices. This work systematically review the research progress and current status of tunable properties in BST ceramics from the three key aspects： the doping modification， the design of multi-phase composites， and the optimization of the preparation process. Furthermore， a valuable reference for the future development and application of high-performance dielectric tunable materials is provided.

Effect of TiO₂ Doping on Strength of YSZ Ceramics at Different Sintering Temperatures

ZHANG Hongjia, FENG Jinyang, CHENG Kaixin, ZHANG Qiang, HAO Xiaoyong

2026, 45(6):  2104-2112.  doi:10.16552/j.cnki.issn1001-1625.2025.1200

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Yttria stabilized zirconia （YSZ） ceramics have emerged as an important material in mechanical and electronic applications owing to their high strength， excellent high-temperature resistance and good biocompatibility. However， the excessively high sintering temperature results in high energy consumption and costs. Therefore， the current research focus on finding ways to lower the sintering temperature while maintaining performance. YSZ ceramics with varying TiO₂ content were prepared by atmospheric pressure sintering at different temperatures. The effect of TiO₂ content on the densification， phase composition and mechanical properties of YSZ ceramics at different sintering temperatures was systematically studied. The results show that the doping of TiO₂ can reduce the sintering temperature of YSZ ceramics， promote grain growth and sintering densification， and is beneficial to stabilize tetragonal phase zirconia. At lower sintering temperatures （1 350， 1 400 ℃）， the flexural strength of YSZ ceramics decreases first and then increases with increasing TiO₂ content （0.5%~7.0%， mole fraction）. The flexural strength of YSZ ceramics with 7.0% TiO₂ is the highest， reaching 530.4 and 576.3 MPa， respectively. At higher sintering temperatures （1 450， 1 500 ℃）， flexural strength generally declines with increasing TiO₂ content， and only trace content （0.5%~1.0%） exhibiting a strengthening effect. Specifically， the flexural strength of YSZ ceramics doping with 1.0% TiO₂ at 1 450 ℃ is 660.7 MPa， and that of YSZ ceramics doping with 0.5% TiO₂ at 1 500 ℃ is 633.1 MPa.

Microstructure and Properties of Al₂O₃/SiC_w Composite Ceramics Prepared by Microwave Sintering and Hot Isostatic Pressing

FAN Xinfang, HONG Dongbo, LIN Liangliang, ZHENG Aiqin, WANG Jue, YIN Zengbin

2026, 45(6):  2113-2121.  doi:10.16552/j.cnki.issn1001-1625.2025.1174

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Alumina （Al₂O₃） ceramics are widely recognized for their high hardness， excellent wear resistance， and outstanding chemical stability， making them highly promising for structural applications. In this study， high-performance Al₂O₃/SiC_w composite ceramics were fabricated using a combined process involving microwave sintering followed by hot isostatic pressing （HIP）. The effects of microwave sintering parameters， silicon carbide whisker （SiC_w） content， and HIP post-treatment on the microstructure and mechanical properties of Al₂O₃/SiC_w were systematically investigated. The results indicate that with 7% （mass fraction） SiC_w addition and microwave sintering at 1 650 ℃ for 10 min， the Al₂O₃/SiC_w achieves optimal mechanical properties， exhibiting a relative density of 99.2%， Vickers hardness of 18.62 GPa， and fracture toughness of 4.85 MPa·m^1/2. After HIP treatment， the properties of the specimens are further improved. In particular， the specimen with 10% SiC_w shows the best mechanical property， with its relative density increasing from 97.55% to 99.56%， Vickers hardness reaching 19.55 GPa， and fracture toughness attaining 5.05 MPa·m^1/2. Compared to the specimen before HIP treatment， the Vickers hardness and fracture toughness are enhanced by 10.8% and 10.0%， respectively.

Preparation of High-Purity Ultrafine Mg-Al Spinel Powder by Double Metal Alkoxide Method

WANG Ying, LEI Muyun, LING Hao, WANG Haili, LI Zhen, HUANG Cunxin

2026, 45(6):  2122-2128.  doi:10.16552/j.cnki.issn1001-1625.2025.1188

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High-purity Mg-Al spinel （MgAl₂O₄） powder with an average grain size D₅₀ of 0.42 μm， low hard agglomeration， and purity higher than 99.99% （mass fraction） was successfully prepared by double metal alkoxide method combined with planetary ball milling technology. By optimizing the alkoxide hydrolysis conditions and ball milling mechanical parameters， the spinel phase powder was synthesized at low temperature and dispersed at the nanoscale， significantly reducing energy consumption. The obtained powder was sintered at 1 550 ℃ under vacuum for 4.0 h at 60 MPa combined with hot isostatic pressing （1 750 ℃， 200 MPa for 2.0 h） post-treatment. High optical quality MgAl₂O₄ transparent ceramics with linear transmittance of up to 83.5%@600 nm （close to the theoretical value of 86%） were successfully prepared. This study confirms that the double metal alkoxide method has significant advantages in preparing ultrafine powder that meet the stringent requirements of transparent ceramics， providing an important powder foundation for the development of high-performance spinel optical materials.

Preparation of Iron Oxide Red from Hydrochloric Acid-Based Titanium White Wastewater and Its Application in Black Ceramic Pigments

DUAN Ning, ZHANG Fan, LU Chenglong, ZHANG Yinfeng, LI Lichi

2026, 45(6):  2129-2140.  doi:10.16552/j.cnki.issn1001-1625.2025.1214

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Titanium white wastewater from the hydrochloric acid route contains abundant ferrous chloride， which can be recovered for resource utilization. This study adopted a purification-oxidation-calcination process to prepare iron oxide red from the waste acid， which was subsequently used as an iron source to synthesize a Fe-Cr black ceramic pigment applied in black ceramics. The effects of reactant molar ratio， initial Fe2? concentration， aeration rate， and oxidation temperature on the preparation of iron oxide yellow were investigated. Furthermore， the influence of calcination temperature on the formation of iron oxide red， the Fe-Cr black pigment， and the coloring performance of the ceramics was examined. The results show that purified ferrous chloride solution， under optimal conditions （molar ratio 2.4∶1， Fe²⁺ concentration 0.5 mol/L， aeration rate 1.5 L/min， oxidation temperature 40 ℃）， yields iron oxide yellow， which after calcination at 750 ℃ produces iron oxide red with a purity of 98.384%， a median particle size of 3.575 μm， and CIELAB color parameters L^*=38， a^*=24.8， b^*=21.5. Using this as raw material， the Fe-Cr black pigment synthesized at 1 250 ℃ exhibits optimal coloring performance in ceramics， presenting a pure black appearance with L^* =36.54， a^* =1.05， b^* =0.86， matching standard reference values closely. This work demonstrates a high-value conversion route for titanium white wastewater， offering both economic and environmental benefits.

Glass

Mechanical and Electrical Properties Regulation of Soda-Lime-Silica Transparent Glass-Ceramics

SUN Sijia, ZHEN Yu, WANG Daojing, SHEN Yi, ZHAO Qian, WEI Tingting, MA Tao, SHAN Wanning, LU Ping, XU Yinsheng

2026, 45(6):  2141-2150.  doi:10.16552/j.cnki.issn1001-1625.2025.1219

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Insulators are specialized insulating components capable of withstanding high voltage and mechanical stress， playing a significant role in overhead transmission lines. However， traditional tempered glass insulators are prone to self-explosion， while ceramic insulators are heavy and opaque， making it difficult to detect fine cracks as well as internal defects and damage. Therefore， there is an urgent need to develop transparent insulating materials with high electrical strength and high mechanical strength. In this work， the soda-lime-silica glass （Na₂O-2CaO-3SiO₂） was selected as the matrix material. A series of glass-ceramics were prepared by introducing nucleating agents and designing appropriate heat treatment schedules. The mechanical and electrical properties of the glass samples were regulated by Al₂O₃ and K₂O. The influence of K₂O and heat treatment process on the crystallization behavior， microstructure， bending strength， breakdown strength and electrical properties of glass-ceramics was systematically explored. The results show that with the increase of K₂O content， the mixed alkali effect arising from the coexistence of Na⁺ and K⁺ leads to an increase in the volume resistivity of the sample. After crystallization， the samples exhibit a transmittance greater than 50% at 500 nm， a volume resistivity greater than 1×10¹¹ Ω·m， a bending strength greater than 120 MPa， a Vickers hardness greater than 6 GPa， a relative dielectric constant of 7~9 （at 1 MHz）， and an electrical breakdown strength greater than 20 kV/mm. These materials show promise for application in the field of insulator materials for power transmission and transformation equipment in high-voltage power grid systems.

Effect of CeO₂ on Crystallization Behavior and Properties of Transparent Lithium Aluminosilicate Glass-Ceramics

WU Lanyu, ZHANG Xianghua, LIU Yaolong, LU Ping, ZHANG Dandan, MA Juping, LI Hanlin, LIN Sihui, XU Yinsheng

2026, 45(6):  2151-2159.  doi:10.16552/j.cnki.issn1001-1625.2025.1213

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The rare earth oxide CeO₂ not only affects the glass melting and refining process， but also controls crystallization and enhances the transmittance of glass， improving the mechanical and radiation resistance properties of glass materials， thereby expanding the application of lithium aluminosilicate （LAS） glass-ceramics in harsh environments such as aerospace. This article investigated the regulatory mechanism of trace CeO₂ doping （≤1.0%， mass fraction） on the structure， crystallization behavior， and properties of LAS glass-ceramics. The results indicate that the introduction of CeO₂ can effectively regulate the content of Q⁴ structural units in the glass network. Moderate CeO₂ （<0.5%） has an inhibitory effect on the crystallization of LAS glass-ceramics， but excessive CeO₂ （≥0.5%） actually promotes crystallization and structural depolymerization. The grain size of LAS glass-ceramics decreases first and then increases with the increase of CeO₂ content. By optimizing the CeO₂ content， the grain refinement of glass-ceramics is realized and its Vickers hardness， fracture toughness， transmittance， and radiation resistance property are improved. When the CeO₂ content is 0.3%， glass-ceramics with fine grains and excellent properties can be obtained， with a Vickers hardness of 7.45 GPa， fracture toughness of 0.93 MPa?m^1/2， and it has good radiation resistance property.

Functional Materials

Sol-Gel Synthesis of Mesoporous Calcium Silicate Humidity-Regulating Material and Its Performance

YANG Xue, JIANG Hongyi

2026, 45(6):  2160-2170.  doi:10.16552/j.cnki.issn1001-1625.2025.1182

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To achieve efficient environmental humidity regulation while reducing energy consumption， this study focused on the pore structure design and performance optimization of mesoporous calcium silicate materials with humidity-regulating capabilities. Employing the sol-gel method combined with vacuum drying， with tetraethyl orthosilicate （TEOS） as the silicon source and calcium nitrate tetrahydrate （Ca（NO₃）₂·4H₂O） as the calcium source， the effects of alcohol-water ratio （molar ratio， n（C₂H₅OH）/n（H₂O）=1/2~1/6）， calcium-silicon ratio （molar ratio， n（Ca）/n（Si）=0.9/1~1.5/1）， and calcination temperature （100~1 000 ℃） on the material structure and properties were systematically investigated. Systematic characterization via FT-IR， XRD， SEM， BET， TG-DTG， and 24 h moisture adsorption/desorption tests revealed structure-property relationships between these parameters and the material’s pore structure， phase composition， and humidity-regulating performance. Results indicate that under optimized conditions of an alcohol-water ratio of 1/4， a calcium-silicon ratio of 1.4/1， and a calcination temperature of 500 ℃， the material exhibits a narrowly distributed mesoporous structure （3.8~20.8 nm） with outstanding humidity-regulating capabilities （24 h moisture absorption rate of 207.36%； 24 h moisture desorption rate of 172.17%）. This study provides a systematic process route and theoretical foundation for developing high-performance mesoporous calcium silicate humidity-regulating materials， holding positive significance for advancing building energy efficiency and green humidity-regulating materials.

Influence of Uniaxial Strain on Effective Mass of Charge Carriers in Bi₂WO₆

LI Jia, WU Peidong, LIU Jian

2026, 45(6):  2171-2180.  doi:10.16552/j.cnki.issn1001-1625.2026.0128

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Band structure， electronic density of states， mechanical properties， and carrier effective mass of Bi₂WO₆ were systematically calculated using first-principles density functional theory. The influence of uniaxial strain applied along the x， y， and z directions on the material’s band structure and the effective mass of generated carriers was thoroughly investigated. The results demonstrate that the calculated elastic constants reveal strong mechanical stability of Bi₂WO₆， along with pronounced anisotropic behavior. The band structure calculations reveal that Bi₂WO₆ is an indirect bandgap semiconductor with a bandgap of 2.422 eV. Under uniaxial strain， the bandgap exhibits tunability， with the maximum variation observed along the x direction. Upon strain application， the electronic bandgap of Bi₂WO₆ can be modulated within the range of 1.851 eV to 2.796 eV. In addition， the effective mass of charge carriers in Bi₂WO₆ can be precisely modulated by applied strain. The disparity between electron and hole effective masses increases markedly with increasing uniaxial tensile strain， thereby significantly promoting the spatial separation of generated electron-hole pairs. This behavior is well consistent with experimental observations showing enhanced pizeocatalytic activity of Bi₂WO₆ powder under strong mechanical stress. This study provides a theoretical foundation for gaining deeper insight into the intrinsic coupling between mechanical strain， band structure， and catalytic activity in piezoelectric catalytic materials.

Road Materials

Mechanical Properties and Microstructure Analysis of Reed Fiber-Reinforced Fluid Fly Ash

XIAO Qingyi, ZHANG Ziteng, MA Mingxiao, JING Wenlong, LI Ziyi

2026, 45(6):  2181-2190.  doi:10.16552/j.cnki.issn1001-1625.2025.1117

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In order to address the cracking problem caused by settlement and drying shrinkage of fluid fly ash materials used in the backfill of bridge and culvert abutments in soft soil areas， this paper investigated the mechanical properties of a reed fiber-reinforced fluid fly ash lightweight subgrade filler. Alkali-treated reed fibers with different content （0.2%~1.0%， mass fraction） were added into fluid fly ash， and the microstructural evolution mechanism of the material was analyzed using scanning electron microscopy. The results show that the optimum reed fiber content is 0.4%. Compared with the control group without reed fiber， the 90 d shrinkage value decreases by 25.8%， the 180 d compressive strength increases by 12.8%， and the 90 d splitting tensile strength increases by 21.2%. The water stability coefficients at 28 and 90 d increase to 0.938 and 0.969， respectively， and the 90 d freeze-thaw stability coefficient reaches 0.941. When the reed fiber content exceeds 0.6%， the overall performance of the composite material decreases. Microstructure analysis shows that the reed fibers form a dense gel-bridge structure with the matrix at the later curing stage， which enhances the crack resistance， strength， and long-term durability of the material.

Optimization of Stabilization Mix Proportion for Gully-Phase Soft Soil in Sichuan Basin Based on Response Surface Methodology

HUANG Rui, KANG Peng, LI Qinliang, WANG Tao, ZOU Dong, ZHANG Junyun, ZHANG Le, CHEN Chunlu

2026, 45(6):  2191-2202.  doi:10.16552/j.cnki.issn1001-1625.2025.1097

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To address the engineering challenges posed by gully-phase soft soil subgrades in the Sichuan Basin， this study developed a composite stabilizer using ordinary Portland cement， fly ash， basalt fiber， and polyvinyl alcohol resin.The unconfined compressive strength was used as the evaluation index to optimize the mix proportion of the stabilizer to enhance its solidification effect on soft soil. Based on the reasonable dosage ranges of each material determined by single-factor experiments， a four-factor， five-level experimental scheme was designed using the central composite design response surface methodology. Quadratic regression models were established between the unconfined compressive strength of the stabilized soil at different curing ages （7， 28， 60 d） and the influencing factors， and the influence laws of individual factors and their interactions on the strength were analyzed. The results show that the established models have good fit （R2>0.952 4）. The optimal mix proportion of the composite stabilizer obtained through model optimization is m（cement）∶m（fly ash）∶m（basalt fiber）∶m（polyvinyl alcohol resin）=8.00∶4.91∶0.34∶0.46. The relative errors between the predicted and experimental strength values at various ages under this proportion are all less than 10%， verifying the model’s reliability. Mechanistic analysis indicates that the cementation from cement hydration products， the micro-aggregate filling effect of fly ash， the reinforcement by basalt fibers， and the network structure formed by polyvinyl alcohol resin collectively enhance the soil’s strength and stability. The study provides a reliable material mix proportion scheme and theoretical basis for the solidification of gully-phase soft soil in the Sichuan basin.

Triaxial Compression and Disintegration Characteristics of Loess Stabilized by Biopolymer-Fiber Composites

NI Jing, ZHANG Hang, ZHU Lili

2026, 45(6):  2203-2214.  doi:10.16552/j.cnki.issn1001-1625.2025.1109

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Loess is a Quaternary sediment extensively distributed in Northwest China and is commonly used as foundation and construction material in engineering projects. Nevertheless， natural loess is featured by loose porous structure and high water sensitivity， leading to rapid strength degradation， collapse， disintegration， and even landslides upon water immersion， which severely threaten the long-term safety of engineering structures. Traditional loess stabilization methods using cement， lime， and fly ash can effectively enhance soil strength but are associated with high carbon emissions and ecological damage， which are inconsistent with China’s dual carbon policy. In response， environmentally friendly biopolymers and natural fibers have emerged as promising alternatives for sustainable soil improvement. This study aims to investigate the feasibility of using xanthan gum （XG）， an anionic biopolymer， combined with coconut shell fiber （CF） to stabilize loess， focusing on shear strength， disintegration resistance， and synergistic reinforcement mechanisms. A series of consolidated-undrained triaxial shear tests， disintegration tests， and scanning electron microscopy （SEM） tests were conducted on composite-stabilized loess with five XG contents （0%， 0.5%， 1.0%， 1.5%， 2.0%） and five CF contents （0%， 0.25%， 0.50%， 0.75%， 1.00%）. Triaxial test results indicate that XG and CF synergistically enhance the shear strength of loess in a dosage-dependent manner. Specifically， XG exhibits a slightly more pronounced effect on cohesion than on the internal friction angle， while CF demonstrates a substantially stronger effect on the internal friction angle than on cohesion， with an improvement amplitude approximately twice that of cohesion. The optimum dosage combination of 2.0% xanthan gum and 1.00% coconut shell fiber increases the cohesion and internal friction angle by 79% and 73% compared with the unamended loess， respectively. Disintegration tests demonstrate that increasing XG and CF contents gradually reduces the disintegration rate and delays the disintegration process， in which XG plays a dominant role. In particular， when the XG dosage increases from 0% to 0.5%， the disintegration rate of stabilized loess decreases by more than 80% regardless of the CF dosage. The optimum dosage combination of 2.0% XG and 1.00% CF allows the stabilized loess to maintain integrity without obvious disintegration， solving the inherent defect that loess is prone to instability upon water immersion. SEM microstructural observations reveal that XG provides cementation and pore-clogging effects by bonding soil particles， filling pores， and forming water-impermeable gel membranes. CF forms a three-dimensional reinforcing network by embedding in the soil matrix， thus promoting stress transfer and restraining crack propagation. Under the synergistic interaction， XG enhances the interfacial bonding between soil particles and fibers， forming a compact “XG-CF-clay” composite matrix that strengthens interfacial restriction and toughening efficiency. This synergistic effect ultimately improves the shear strength and water stability of loess. The results of this study provide important data and theoretical support for the application and promotion of eco-friendly biopolymer-based soil stabilization technologies in loess areas.