Cement & concrete composites最新文献_第7页

Simultaneous alkalinity neutralization and reactivity enhancement of red mud through CO2 mineralization 二氧化碳矿化同时中和赤泥的碱性和增强反应性

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-12-04 DOI: 10.1016/j.cemconcomp.2025.106420

Chao Zhang , Xiangkun Zhang , Zhijuan Hu , Wenlong Wang , Yingliang Zhao , Peiliang Shen

The high alkalinity and low hydraulic reactivity of red mud (RM) severely restrict its application in cement or concrete industry. In this study, an innovative CO₂ mineralization approach for simultaneous alkalinity neutralization and reactivity enhancement of RM was developed, aiming to promote its use as a supplementary cementitious material (SCM). The results demonstrate that CO₂ mineralization significantly mitigates the alkalinity of RM, reducing the pH from 12.65 to 7.59. The carbonated RM exhibited remarkable pozzolanic activity, with a strength activity index of 113 % (7-day) and 109.8 % (28-day), confirming its potential as a highly active SCM. The carbonation of RM demonstrated exceptional CO₂ sequestration capacity, capturing 24.34 g of CO₂ per 100 g of RM, achieving a carbonation degree of 62.89 %. Alkalinity neutralization primarily occurs through carbonation reactions between CO₂ and alkaline components, generating stable carbonate precipitates. Furthermore, carbonation kinetics analysis revealed a 60.5 % reduction in average particle size and a 235.1 % increase in specific surface area of RM, indicating significant microstructural refinement. Rapid carbonation of C₃S, C₂S, sodalite, perovskite and jennite to the formation of calcite, metastable CaCO₃ and silica-alumina gel, indicating mineral reconfiguration of RM. The combined effects of microstructure refinement and mineral reconfiguration jointly enhanced the pozzolanic activity of RM. Overall, these findings establish RM carbonation as a dual-purpose solution for sustainable waste valorization and carbon capture, offering both technical and environmental advantages for industrial implementation.

赤泥的高碱度和低水力反应性严重制约了其在水泥和混凝土工业中的应用。在本研究中，开发了一种创新的二氧化碳矿化方法，用于同时中和碱性和增强反应性，旨在促进其作为补充胶凝材料（SCM）的应用。结果表明，CO2矿化显著降低了RM的碱度，将pH从12.65降低到7.59。碳酸化RM表现出显著的火山灰活性，强度活性指数为113%（7天）和109.8%（28天），证实了其作为高活性SCM的潜力。RM的碳化表现出优异的CO2固存能力，每100 g RM可捕获24.34 g CO2，碳化度达到62.89%。碱度中和主要通过CO2和碱性组分之间的碳化反应发生，产生稳定的碳酸盐沉淀物。此外，碳化动力学分析显示，RM的平均粒径降低了60.5%，比表面积增加了235.1%，表明微观结构得到了显著改善。C3S、C2S、钠钛矿、钙钛矿和闪铁矿快速碳化形成方解石、亚稳CaCO3和硅铝凝胶，表明RM的矿物重构。显微结构细化和矿物重构的共同作用增强了RM的火山灰活性。总的来说，这些发现确立了RM碳化作为可持续废物增值和碳捕获的双重目的解决方案，为工业实施提供了技术和环境优势。

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引用次数: 0

Size effect and mechanism-based multiphase modeling of strain-hardening behavior of Ultra-High-Strength Engineered Cementitious Composites (UHS-ECC) 超高强度工程胶凝复合材料（UHS-ECC）应变硬化行为的尺寸效应及多相模型

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-12-02 DOI: 10.1016/j.cemconcomp.2025.106424

Ji-Xiang Zhu , Bo-Tao Huang , Wei-He Liu , Ling-Yu Xu , Kai-Di Peng , Jian-Guo Dai

In order to facilitate structural applications, a systematic and rational assessment of the size effect on the tensile performance of Ultra-High-Strength Engineered Cementitious Composites (UHS-ECC) is of crucial significance. To achieve this goal, direct tension tests were conducted on dumbbell-shaped UHS-ECC specimens of three different thicknesses (i.e., 10, 20, and 30 mm). Three different lengths (i.e., 6, 12, and 18 mm) of polyethylene (PE) fibers were also studied. As the specimen thickness increased, the tensile strength of UHS-ECC decreased, while the tensile strain capacity was unaffected. Increasing the fiber length from 6 mm to 12 mm led to significant enhancements of both the tensile strength and strain capacity of UHS-ECC, but further increasing the fiber length from 12 mm to 18 mm only slightly improved the tensile strain capacity with the tensile strength nearly unchanged. Mechanism-based finite element (MMFE) modeling was conducted to interpret experimental observations and elucidate the underlying physical mechanisms. The numerical analysis demonstrated that the experimental results could be accurately predicted by appropriately selecting fiber orientation distributions, indicating that the size effect and fiber length effect were strongly, if not fully, associated with the fiber orientation distributions. Specifically, thicker specimens were related to higher fiber orientations, which was consistent with the wall effect. Longer fibers were correlated with higher fiber orientations, probably due to the tendency of longer PE fibers to become folded during the mixing process. These folded fibers exhibited a smaller projected length in the tensile direction and reduced crack bridging capacity, resulting in effects similar to increased fiber orientation. The findings in this study provide a fundamental basis for optimizing fiber length and specimen thickness to mitigate size effects and to enhance the tensile performance of UHS-ECC in structural applications.

系统、合理地评价超高强度工程胶凝复合材料（UHS-ECC）的尺寸效应对其拉伸性能的影响，对其结构应用具有重要意义。为此，对哑铃形UHS-ECC试件进行了10、20、30 mm三种不同厚度的直接拉伸试验。还研究了三种不同长度的聚乙烯（PE）纤维（即6,12和18mm）。随着试件厚度的增加，UHS-ECC的抗拉强度降低，但抗拉应变能力不受影响。当纤维长度从6 mm增加到12 mm时，UHS-ECC的抗拉强度和应变能力都得到了显著提高，而当纤维长度从12 mm增加到18 mm时，UHS-ECC的抗拉强度几乎没有变化，但拉伸应变能力的提高幅度很小。采用基于力学的有限元（MMFE）建模来解释实验观察结果并阐明其潜在的物理机制。数值分析表明，适当选择纤维取向分布可以准确地预测实验结果，表明尺寸效应和纤维长度效应与纤维取向分布有很强的相关性，如果不是完全相关的话。具体而言，较厚的试样与较高的纤维取向有关，这与壁效应一致。较长的纤维与较高的纤维取向相关，这可能是由于较长的PE纤维在混合过程中倾向于折叠。这些折叠的纤维在拉伸方向上显示出较小的投影长度，并且降低了裂缝桥接能力，导致类似于纤维取向增加的效果。本研究结果为优化纤维长度和试样厚度，以减轻尺寸效应，提高UHS-ECC在结构应用中的拉伸性能提供了基础依据。

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引用次数: 0

How about improving the lime-hemp concrete properties using bio-based polymer additives? 如何使用生物基聚合物添加剂来改善石灰-大麻混凝土的性能？

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-12-02 DOI: 10.1016/j.cemconcomp.2025.106422

Haichuan Liu, Kamilia Abahri, Rachid Bennacer

The construction sector's high energy use and CO₂ emissions drive the search for sustainable materials such as bio-aggregate concrete. Hemp concrete, composed of hemp shiv and lime, offers benefits including a negative carbon footprint, thermal and acoustic insulation, and moisture regulation but suffers from low strength and durability. Literature studies have shown that bio-based polymers can improve the properties of lime-based materials. This study aims to evaluate the potential of using biopolymers to improve the comprehensive properties of lime-based hemp concrete. Investigated the effect of three bio-based polymers (casein, κ-carrageenan, and hydroxypropyl methylcellulose (HPMC)) on the hygrothermal properties (thermal conductivity, WVP, and MBV), mechanical strength, and capillary water absorption. Additionally, mineralogical and microstructural analyses were conducted using XRD, TG, and SEM. Results showed that within 0.5–5 % of contents, three bio-based polymers had little effect on the hygrothermal performance of hemp concrete but significantly affected mechanical strength and capillary water absorption. Adding casein hindered binder hydration and carbonation, reducing compressive strength and increasing water absorption, despite improving hygrothermal properties. Incorporating 0.5 % κ-carrageenan slightly increased compressive strength, but higher contents resulted in strength loss and higher capillary water absorption. Adding HPMC offered the most balanced performance, with 5 % content increasing strength by 155 %, reducing water absorption by 29 %, while preserving thermal conductivity and moisture buffering close to the reference group. These effects were attributed to enhanced interface bonding and the matrix itself due to HPMC's physicochemical effect. The findings contribute to developing enhanced bio-aggregate-based concrete, advancing their applicability in sustainable construction.

建筑行业的高能耗和二氧化碳排放促使人们寻找可持续材料，如生物骨料混凝土。大麻混凝土由大麻叶和石灰组成，具有负碳足迹、隔热和隔音、调节水分等优点，但强度和耐久性较低。文献研究表明，生物基聚合物可以改善石灰基材料的性能。本研究旨在评价利用生物聚合物改善石灰基大麻混凝土综合性能的潜力。研究了三种生物基聚合物（酪蛋白、κ-卡拉胶和羟丙基甲基纤维素（HPMC））对复合材料的湿热性能（导热系数、WVP和MBV）、机械强度和毛细吸水率的影响。此外，采用XRD、TG和SEM对样品进行了矿物学和微观结构分析。结果表明：在掺入量的0.5 ~ 5%范围内，3种生物基聚合物对大麻混凝土的湿热性能影响不大，但对其机械强度和毛细吸水率有显著影响；添加酪蛋白阻碍了粘结剂的水化和碳化，降低了抗压强度，增加了吸水率，尽管改善了湿热性能。掺入0.5% κ-卡拉胶可略微提高材料的抗压强度，但含量越高，强度损失越大，毛细吸水率越高。添加HPMC提供了最平衡的性能，5%的含量增加了155%的强度，减少了29%的吸水性，同时保持了热导率和湿缓冲接近参考组。这些影响是由于HPMC的物理化学作用增强了界面键和基体本身。研究结果有助于增强生物骨料基混凝土的发展，提高其在可持续建筑中的适用性。

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引用次数: 0

The rate-dependent fiber-matrix interface in ultra high-performance fiber reinforced concrete: Interface property determination 超高性能纤维增强混凝土中速率相关纤维-基体界面：界面性能测定

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-12-01 DOI: 10.1016/j.cemconcomp.2025.106423

Ji Woon Park , John E. Bolander , Yun Mook Lim

Quantifying the rate dependency of the fiber-matrix interface is crucial to evaluating the dynamic behavior of fiber-reinforced cementitious composites (FRCCs). Numerous studies have directly conducted high-speed pullout tests on single or multiple fibers. However, current test methods are limited with respect to quantifying the effects of random fiber dispersion, irregular crack surfaces, and the resulting variations in the inclination and embedment length of fibers within FRCC materials. To address these needs, this study uses a novel inverse analysis procedure to accurately capture the dynamic pullout behavior of randomly distributed fibers in composite materials. This has been achieved using a recently developed multi-scale lattice model combined with an optimization algorithm. The numerical model is capable of simulating the mesoscale response of FRCCs while accounting for the rate-dependent fiber-matrix interface at the microscale. The inverse determination of rate-dependent behavior of the reinforcing fibers in strain hardening cementitious composites is consistent with experimental findings. The results provide new insights into the effects of multiple fiber bundling and inclination within the cementitious composite specimens. In particular, the analysis showed that multiple randomly oriented fibers caused more matrix spalling than single-fiber pullout tests, in agreement with experimental observations. Additionally, fiber pullout behavior was governed more by the propagation speed of the dominant crack than by the overall specimen displacement rate.

量化纤维-基体界面的速率依赖关系是评价纤维增强胶凝复合材料动态性能的关键。许多研究直接对单根或多根纤维进行了高速拉拔试验。然而，目前的测试方法在量化纤维随机分散、不规则裂纹表面以及纤维在FRCC材料中倾角和嵌入长度的变化的影响方面是有限的。为了满足这些需求，本研究使用了一种新颖的逆分析程序来准确捕获复合材料中随机分布的纤维的动态拉拔行为。这已经实现了使用最近开发的多尺度晶格模型与优化算法相结合。该数值模型能够模拟纤维碳纤维的中尺度响应，同时在微观尺度上考虑速率相关的纤维-基质界面。应变硬化胶凝复合材料中增强纤维速率依赖行为的逆测定与实验结果一致。研究结果为研究胶凝复合材料试件中多纤维束和倾角的影响提供了新的思路。特别是，分析表明，与单纤维拉拔试验相比，多个随机取向纤维引起的基体剥落更多，这与实验观察结果一致。此外，纤维的拉拔行为更多地受主导裂纹扩展速度的影响，而不是受试件整体位移率的影响。

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引用次数: 0

Local bond-slip behavior and mechanisms of steel fiber-UHPC matrix interface modified by nano-engineering 纳米改性钢纤维- uhpc基体界面的局部粘结滑移行为及机理

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-11-30 DOI: 10.1016/j.cemconcomp.2025.106421

Xinyue Wang , Xinkai Ma , Ashraf Ashour , Linwei Li , Qishuai Wu , Liangsheng Qiu , Baoguo Han

The bond performance at the interface between steel fibers and the ultra-high-performance concrete (UHPC) matrix plays a critical role in determining the mechanical behavior of UHPC. While nano-engineering presents promising strategies to strengthen this interface, the localized bond-slip behavior of steel fibers in nano-engineered UHPC is not fully understood, owing to the complex microstructural features and pronounced stress heterogeneity along the interface resulting from the fiber-matrix modulus disparity. Combining pull-out tests, microstructural characterizations, theoretical modeling, and numerical simulations, this study elucidates two distinct mechanisms responsible for bond enhancement induced by nanofillers: the interface nano-modification effect and the transition zone nano-modification effect. The relative scale between nanofillers and steel fibers governs the enrichment or dilution of nanofillers at the interface, thereby affecting the modification efficacy within the transition zone. These mechanisms collectively contribute to a notable improvement in interfacial bond strength, reaching a peak value of 11.73 MPa—exceeding all previously reported results. The derived bond-slip constitutive models, grounded in these mechanistic insights, indicate that although nano-engineering can substantially improve the strength and durability of UHPC, it also leads to a reduction in ductility.

钢纤维与超高性能混凝土基体界面的粘结性能对超高性能混凝土的力学性能起着至关重要的作用。虽然纳米工程提出了有希望的增强该界面的策略，但由于复杂的微观结构特征和纤维-基质模量差异导致的界面上明显的应力不均匀性，纳米工程UHPC中钢纤维的局部粘结滑移行为尚未完全了解。结合拉出试验、微观结构表征、理论建模和数值模拟，本研究阐明了纳米填料诱导键增强的两种不同机制：界面纳米修饰效应和过渡区纳米修饰效应。纳米填料与钢纤维的相对尺度决定着界面处纳米填料的富集或稀释，从而影响过渡区内纳米填料的改性效果。这些机制共同促进了界面结合强度的显著提高，达到11.73 mpa的峰值，超过了之前报道的所有结果。基于这些力学见解的黏结-滑移本构模型表明，尽管纳米工程可以大大提高UHPC的强度和耐久性，但它也会导致延展性的降低。

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引用次数: 0

Development of ultra-high-performance concrete incorporating nanobubble water and steel slag powder: Mechanical and microstructural optimization 纳米气泡水与钢渣粉混合的高性能混凝土的研制：力学与微观结构优化

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-11-29 DOI: 10.1016/j.cemconcomp.2025.106419

Rongzhen Piao , Hong-Joon Choi , Seong-Jae Kim , Wengui Li , Doo-Yeol Yoo

This study aimed to develop low-carbon sustainable ultra-high-performance concrete (UHPC) by partially replacing ordinary Portland cement with steel slag powder (SSP) and using different types of mixing water—tap water, nanobubble water (NW), and carbon dioxide NW (CNW). NW improved particle dispersion and lubrication, thereby enhancing flowability, whereas CNW slightly reduced flowability owing to localized carbonation and moisture loss. SSP addition improved workability by weakening interparticle van der Waals forces. Both NW and CNW accelerated hydration. CNW also induced in-situ carbonation and generated nanoscale calcium carbonate, thus partially inhibiting C–S–H formation. Fourier transform infrared (FTIR) analysis confirmed an increase in silicate polymerization by CNW and a decrease in hydration products at SSP replacement ≥20 %. NW and CNW improved strength by refining the pore structure and enhancing fiber–matrix bonding. Strength increased at SSP replacement ratios of up to 20 % but decreased at ratios ≥30 % because of insufficient hydration and a weak microstructure. The specimen prepared using CNW and an SSP replacement ratio of 20 % (CNW20) achieved the highest strength, with compressive and tensile strengths 6.2 % and 17.5 % higher than those of the control, respectively. CNW delayed crack initiation and reduced strain localization. Moderate SSP contents (≤20 %) improved crack dispersion by enhancing the integrity of the interfacial transition zone. CNW20 showed optimal cracking resistance, with a 43.5 % higher strain energy density and 18.3 % more microcracks. These findings demonstrate that solid waste utilization can be integrated with in-situ carbon capture to develop ecofriendly UHPC.

本研究旨在通过钢渣粉（SSP）部分替代普通硅酸盐水泥，并使用不同类型的混合水——自来水、纳米泡水（NW）和二氧化碳NW （CNW）——开发低碳可持续高性能混凝土（UHPC）。NW改善了颗粒的分散和润滑，从而增强了流动性，而CNW由于局部碳化和水分损失而略微降低了流动性。SSP的加入通过减弱粒子间范德华力改善了可加工性。NW和CNW都加速了水化。CNW还可以诱导原位碳化，生成纳米级碳酸钙，从而部分抑制C-S-H的形成。傅里叶变换红外（FTIR）分析证实，CNW增加了硅酸盐聚合，当SSP替代量≥20%时，水化产物减少。NW和CNW通过改善孔隙结构和增强纤维-基质结合来提高强度。当SSP替换率达到20%时，强度增加，但当SSP替换率≥30%时，由于水化不足和微观结构薄弱，强度下降。使用CNW和SSP替换率为20% （CNW20）制备的试样强度最高，抗压强度和抗拉强度分别比对照提高8.9%和12%。CNW延迟裂纹萌生，降低应变局部化。适量SSP含量（≤20%）通过增强界面过渡区的完整性来改善裂纹的分散。CNW20的抗裂性能最佳，应变能密度提高43.5%，微裂纹增加18.3%。这些研究结果表明，固体废物利用可以与原位碳捕获相结合，以发展生态友好的UHPC。

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引用次数: 0

Magneto-responsive flow behavior and early-age microstructural evolution of 3D printing lightweight concrete with fly ash cenospheres 3D打印粉煤灰微球轻混凝土的磁响应流动行为及早期微结构演化

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-11-29 DOI: 10.1016/j.cemconcomp.2025.106411

Jielin Tao , Shengming Hu , Zhenhua Duan , Dengwu Jiao

This study develops a magneto-responsive lightweight concrete with fly ash cenospheres (FACs) and micron-sized Fe₃O₄ particles (MPs) to address the critical challenge of balancing extrudability and buildability in 3D concrete printing. By applying controlled magnetic fields synchronized with printing stages, the rheological properties are dynamically adjusted through magnetic particles reorganization. The integrated methodology combines time-dependent rheological tests (including flowability at 0–30 min, shape retention at 20–23 min, and penetration resistance at 30–60 min) with microscale characterization (i.e., XRD, SEM-EDS, and X-CT) and interparticle magnetic force calculation. The results demonstrate that horizontal magnetic field-driven particle rearrangement occurs without chemical phase changes, with the optimal performance at water-to-binder (w/b) ratio of 0.37 where concrete viscosity enables stable magnetic network formation. SEM-EDS and X-CT analyses confirm the alignment of magnetic particles parallel to horizontal magnetic field, correlating with directional strength influence. Additionally, SEM-EDS further reveals preferential MPs accumulation at FACs interfaces after applying long-term horizontal magnetic field for 24 h. Furthermore, this study establishes a fundamental framework for magnetically controllable lightweight concrete, enabling real-time rheology adjustment during 3D printing to achieve adaptive and mechanically robust structures through magnetic-directed microstructural technology. This method can extend the printable time window by leveraging the increasing flowability enhancement effect of MP and resolve the extrudability-buildability conflict by providing high flowability without magnetic field and structural stability under a horizontal magnetic field (achieving an 85.1 % deformation reduction during stacking).

本研究开发了一种具有粉煤灰微球（FACs）和微米级Fe3O4颗粒（MPs）的磁响应轻量化混凝土，以解决3D混凝土打印中平衡可挤压性和可建造性的关键挑战。通过施加与印刷阶段同步的可控磁场，通过磁性颗粒重组来动态调节流变性能。综合方法结合了随时间变化的流变学测试（包括0-30分钟的流动性，20-23分钟的形状保持，30-60分钟的渗透阻力），微观表征（即XRD， SEM-EDS和X-CT）和颗粒间磁力计算。结果表明，水平磁场驱动的颗粒重排发生在没有化学相变化的情况下，当水胶比（w/b）为0.37时，混凝土粘度能够稳定形成磁网，其性能最佳。SEM-EDS和X-CT分析证实磁颗粒的排列平行于水平磁场，与方向强度的影响有关。此外，SEM-EDS进一步揭示了长期水平磁场作用24小时后，在FACs界面上优先积累MPs。此外，本研究建立了磁可控轻质混凝土的基本框架，可以在3D打印过程中实现实时流变调节，通过磁定向微结构技术实现自适应和机械坚固的结构。这种方法可以利用MP增强流动性的效果来延长可打印时间窗口，并通过在无磁场的情况下提供高流动性和水平磁场下的结构稳定性（在堆叠过程中实现85.1%的变形减少）来解决可挤出性与可构建性的冲突。

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引用次数: 0

Elucidating the effect of modulus of sodium silicate on microstructural and mechanical properties of alkali activated slag pastes 研究了水玻璃模量对碱活性矿渣膏微观结构和力学性能的影响

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-11-28 DOI: 10.1016/j.cemconcomp.2025.106415

Dongdong Jiang , Zuhua Zhang , Genshen Li , Caijun Shi

The modulus (Ms) of sodium silicate solution has both qualitative and quantitative effects on the reaction products formed in alkali activated slag (AAS) pastes, primarily consisting of C-(N)-A-S-H gels and hydrotalcite phases. Various intrinsic characteristics of these reaction products exhibit significant variations as a function of Ms, such as the chemistry of both pure phases, as well as the nanostructure and morphology of gel phases. Moreover, the volume fraction of reaction products, identified as the first-order parameter explaining the compressive strength of AAS pastes, is synergistically affected by the reaction degree of slag particles and the solid-phase quantity transformed from soluble silicate species supplied by sodium silicate solution. Specifically, the silicon content supplied by sodium silicate solution at Ms of 2 is comparable to the dissolved silicon content as the reaction degree of slag particles reaches ∼36 %. In addition, the inner products of AAS pastes exhibit superior micromechanical properties, primarily due to the enrichment of hydrotalcite phases rather than contributions from the solid skeleton of gel phases. Their relative proportion within reaction products exerts more significant influence on the compressive strength of AAS pastes than the reaction degree of slag particles.

水玻璃溶液的模量（Ms）对碱活性渣（AAS）膏体（主要由C-(N) a - s - h凝胶和水滑石相组成）形成的反应产物有定性和定量的影响。这些反应产物的各种内在特征表现出显著的变化，如纯相的化学性质，以及凝胶相的纳米结构和形态。反应产物的体积分数作为解释AAS膏体抗压强度的一级参数，受矿渣颗粒的反应程度和由硅酸钠溶液提供的可溶性硅酸盐转化的固相数量的协同影响。具体来说，当渣粒反应程度达到~ 36%时，硅酸钠溶液在Ms = 2时提供的硅含量与溶解硅含量相当。此外，AAS膏体的内部产物表现出优异的微力学性能，这主要是由于水滑石相的富集，而不是凝胶相的固体骨架的贡献。它们在反应产物中的相对比例对AAS膏体抗压强度的影响比对渣粒反应程度的影响更为显著。

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引用次数: 0

Composition-driven microstructure refinement in geopolymers enabled by copper slag-based core-shell structure 铜渣基核壳结构驱动的地聚合物微观结构细化

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-11-28 DOI: 10.1016/j.cemconcomp.2025.106414

Longfei Zhang , Yuxuan Chen , Wenkai Wu , Zhaokang Liu , Qingliang Yu

Geopolymers face limited load-bearing applications due to low elastic modulus and high porosity caused by weak N-A-S-H gels. Traditional modification methods often fail to address interfacial inertness or porosity issues. This study develops a novel copper slag (CS) based core-shell structure featuring an iron-rich core and nano-silica (NS) coating to enhance geopolymer stiffness synergistically. High-purity NS (358 m²/g) synthesized via acid leaching and complexation forms a dense 0.6 μm shell using polyvinylpyrrolidone (PVP). Adding 2 wt% composite optimizes reaction kinetics, increasing 28-day compressive strength by 21.30% (54.3 MPa) and elastic modulus by 26.41% (12.11 GPa), surpassing ordinary Portland cement at equivalent strength. The iron-rich core reduces harmful macro-pores by 8.13%, while the NS shell promotes Al³⁺ substitution for Si⁴⁺, promoting the preferential formation of dense C-A-S-H gels. This dual mechanism achieves high synergy (coefficient = 1.35), enabling advancing sustainable high-performance geopolymers with combined environmental and structural benefits. These findings suggest various promising applications in such as high-rise buildings and large-span bridges.

由于弱N-A-S-H凝胶导致的低弹性模量和高孔隙率，地聚合物的承载应用受到限制。传统的改性方法往往不能解决界面惰性或孔隙度问题。本研究开发了一种新型的铜渣（CS）基核壳结构，该结构具有富铁核和纳米二氧化硅（NS）涂层，以协同提高地聚合物的刚度。采用酸浸法制备高纯度NS (358 m2/g)，并以聚乙烯吡咯烷酮（PVP）络合形成致密的0.6 μm壳层。添加2 wt.%的复合材料优化了反应动力学，28天抗压强度提高了21.30% (54.3 MPa)，弹性模量提高了26.41% (12.11 GPa)，超过了同等强度的普通硅酸盐水泥。富铁核减少了8.13%的有害大孔，而NS壳促进Al3+取代Si4+，促进致密的C-A-S-H凝胶的优先形成。这种双重机制实现了高协同效应（系数= 1.35），使可持续高性能地聚合物具有环境和结构双重效益。这些发现表明了在高层建筑和大跨度桥梁等各种有前景的应用。

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引用次数: 0

Properties and sealing performance of an ultra high-durability cement mortar plug under simulated downhole conditions 模拟井下条件下超高耐久性水泥砂浆桥塞的性能与密封性能

IF 13.1 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2025-11-27 DOI: 10.1016/j.cemconcomp.2025.106417

Ethan Yen, Bora Gencturk, Xiaoying Pan, Huanpeng Hong

Methane leakage from abandoned oil and gas wells is driven by compromised sealing through the cement matrix and at cement–steel and cement–formation interfaces. This study evaluates an ultra high-durability cement mortar plug (UHD-CMP) designed to address the high shrinkage, low tensile strength, and poor interface bonding of conventional mortars under downhole conditions. Compressive strength, shrinkage, porosity, gas permeability, and interface bond strength were measured under five curing regimes simulating thermal and moisture exposures. Three shrinkage-reducing admixtures were assessed: magnesium oxide (MgO), calcium oxide (CaO)-based expansive agent, and a surfactant-based reducer (SRA). UHD-CMP achieved compressive strengths up to 162 MPa, more than twice that of conventional mortars, porosity reductions of up to 71 %, and bulk gas permeability as low as 3.98 × 10⁻²⁰ m², up to five orders of magnitude lower than conventional mortars. Under prolonged moisture exposure at 70 % relative humidity, MgO- and SRA-modified UHD-CMP retained shear bond strengths of 1.5–2.3 MPa and 0.8–1.4 MPa, respectively, compared to 0.2 MPa or less for conventional mortars. Normal tensile bond strength was also significantly higher, with UHD-CMP maintaining approximately 0.44–0.46 MPa versus 0.09–0.11 MPa for conventional mortars under the same conditions. At elevated temperatures of 50–80 °C and 50 % relative humidity, shear bond strength decreased compared to standard curing but remained substantially higher than that of conventional mortars, which failed at 0.2 MPa or less. These results demonstrate UHD-CMP's potential for long-term sealing durability in well abandonment applications.

废弃油气井的甲烷泄漏是由于水泥基质、水泥-钢和水泥-地层界面的密封受损造成的。该研究评估了一种超高耐久性水泥砂浆桥塞（UHD-CMP），该桥塞旨在解决常规砂浆在井下条件下的高收缩率、低抗拉强度和界面粘结性差的问题。抗压强度、收缩率、孔隙率、透气性和界面粘结强度在模拟热和湿暴露的五种固化制度下进行了测量。评估了三种减少收缩的外加剂：氧化镁（MgO）、氧化钙（CaO）基膨胀剂和表面活性剂基还原剂（SRA）。UHD-CMP的抗压强度高达162 MPa，是传统砂浆的两倍多，孔隙率降低高达71%，整体渗透率低至3.98 × 10-20 m2，比传统砂浆低5个数量级。在70%的相对湿度下，MgO和sra改性的UHD-CMP分别保持了1.5-2.3 MPa和0.8-1.4 MPa的剪切强度，而传统砂浆的剪切强度为0.2 MPa或更低。UHD-CMP的正常抗拉强度也显著提高，在相同条件下，UHD-CMP的抗拉强度约为0.44-0.46 MPa，而传统砂浆的抗拉强度为0.09-0.11 MPa。在50-80°C和50%相对湿度的高温下，与标准养护相比，抗剪粘结强度有所下降，但仍远高于传统砂浆，后者在0.2 MPa或更低的温度下失效。这些结果表明，UHD-CMP在弃井应用中具有长期密封耐久性的潜力。

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