Cement & concrete composites最新文献_第8页

Unraveling the multiscale enhancement mechanism of nano-Al2O3 on subzero-prepared alkali-activated slag paste 揭示了纳米al2o3在亚零制备碱活性矿渣膏体上的多尺度强化机理

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

Cement & concrete composites

Pub Date : 2025-11-26 DOI: 10.1016/j.cemconcomp.2025.106418

Jin Xu, Hongen Zhang, Qiang Ren, Wenting Li, Bei He, Zhengwu Jiang

Alkali-activated materials show promise for in-situ subzero preparation due to alkaline activators' lower freezing point. Nanomaterials offer potential to enhance mechanical performance, but their enhancement mechanisms under subzero require deeper systematic exploration. This study investigated the performance of alkali-activated slag paste (AASP) prepared in-situ over 20 °C to −20 °C and explored the modification mechanisms of nano-Al₂O₃ (NA) under subzero temperatures with MIP, TGA, SEM-EDS, and ²⁹Si NMR technologies. The study showed that the compressive strength of AASP significantly weakened, closely associated with the reduction in C-A-S-H content and the decline in polycondensation degree as the reaction temperature decreased. Furthermore, the pore structure deteriorated and carbonation intensified. NA had high reactivity, could provide additional aluminum phase through pozzolanic reaction, and also had a nucleation effect. AASP improved the production of C-A-S-H through the coupling of the above effects at the early stage of product formation. Appropriate NA of 0.5 wt% facilitated the formation and polycondensation of C-A-S-H and optimized the pore distribution, but excessive addition led to an increased proportion of large and harmful pores, primarily due to agglomeration effects. This study clarified the deterioration mechanisms of subzero-prepared AASP and the multiscale enhancement strategies using nanomaterials, establishing reaction process models that offer critical insights for engineering applications in cold climates.

由于碱性活化剂的冰点较低，碱活化材料有望在低温原位制备。纳米材料具有提高机械性能的潜力，但其在低温条件下的增强机制需要更深入的系统探索。本研究考察了在20℃~ -20℃条件下原位制备的碱活性矿渣膏体（AASP）的性能，并利用MIP、TGA、SEM-EDS和29Si NMR等技术探讨了纳米al2o3 （NA）在零下温度下的改性机理。研究表明，AASP的抗压强度明显减弱，这与随着反应温度的降低，C-A-S-H含量的降低和缩聚度的下降密切相关。孔隙结构恶化，碳酸化加剧。NA具有较高的反应活性，可以通过火山灰反应提供额外的铝相，并具有成核作用。在产物形成初期，AASP通过上述效应的耦合提高了C-A-S-H的产量。适量添加0.5 wt.%的NA有利于C-A-S-H的形成和缩聚，优化了孔的分布，但过量添加会导致大孔和有害孔的比例增加，这主要是由于团聚效应。本研究阐明了亚零度制备的AASP的劣化机制和使用纳米材料的多尺度增强策略，建立了反应过程模型，为寒冷气候下的工程应用提供了重要见解。

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引用次数: 0

Insight into a novel polycarboxylate superplasticizer with crack resistance for cement-based materials: synthesis, performance and mechanisms 一种新型抗裂聚羧酸型水泥基材料减水剂：合成、性能和机理

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

Cement & concrete composites

Pub Date : 2025-11-26 DOI: 10.1016/j.cemconcomp.2025.106413

Kai Ma , Wenhao Luo , Yali Li , Xingyu Gan , Lingchao Lu , Laibo Li

The inevitable volume shrinkage of concrete during the hardening process can lead to the formation of cracks. The existence of cracks can significantly reduce the mechanical properties and durability of concrete. A novel polycarboxylate superplasticizer (NPM) with crack resistance was designed to improve the crack resistance of cement-based materials by regulating the molecular structure of polycarboxylate superplasticizers. The structure, molecular weight and reaction degree of NPM were precisely determined. The effect of NPM on the mechanical performance of cement-based materials has been comprehensively analyzed. The results revealed that the NPM can reduce the peak heat release of cement hydration and increase the cumulative heat of cement hydration. The autogenous shrinkage, drying shrinkage, cracking index and harmful pores of the sample were decreased by 87.0 %, 48.83 %, 51.80 %, and 27.21 %, respectively. The improved crack resistance can be attributed to the introduction of amphiphilic groups, which effectively reduce surface tension and capillary stress within the pore solution, thereby mitigating the shrinkage and cracking behaviour of the cement-based materials.

混凝土在硬化过程中不可避免的体积收缩会导致裂缝的形成。裂缝的存在会显著降低混凝土的力学性能和耐久性。设计了一种新型抗裂聚羧酸酯型高效减水剂（NPM），通过调节聚羧酸酯型高效减水剂的分子结构来提高水泥基材料的抗裂性能。精确测定了NPM的结构、分子量和反应度。综合分析了NPM对水泥基材料力学性能的影响。结果表明：NPM能降低水泥水化峰值放热，增加水泥水化积热；试样的自收缩率、干收缩率、开裂指数和有害孔隙率分别降低了87.0%、48.83%、51.80%和27.21%。抗裂性能的提高可归因于两亲性基团的引入，这有效地降低了孔隙溶液中的表面张力和毛细应力，从而减轻了水泥基材料的收缩和开裂行为。

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引用次数: 0

Alkali-activated metakaolin geopolymers as structural electrolytes: Insights into structure–function relationships and energy storage potential 碱活化偏高岭土聚合物作为结构电解质：结构-功能关系和储能潜力的见解

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

Cement & concrete composites

Pub Date : 2025-11-26 DOI: 10.1016/j.cemconcomp.2025.106407

Jiaxi Mao , Suxi Wang , Wentao Jia , Yi Liu , Shikun Chen , Yajun Zhang , Dongming Yan

The rapid growth of distributed and renewable energy systems has created an urgent demand for structural materials capable of simultaneously providing mechanical support and energy‐storage functionality. Conventional cementitious materials, however, exhibit low ionic conductivity and poor electrochemical activity, limiting their use in multifunctional energy‐storage structures. To address this challenge, this study explores the development of alkali‐activated metakaolin (MK) geopolymers modified with different sodium salts (Na₂SO₄, NaCl, and NaOH) as structural solid electrolytes. The incorporation of sodium salts enhanced the ionic conductivity and capacitive behavior of the MK‐based electrolytes. Results showed that the incorporation of sodium salts significantly enhanced the ionic conductivity and capacitive performance of the geopolymer electrolytes. The Na₂SO₄‐modified sample (MK‐S) exhibited the highest ionic conductivity of 33.22 mS cm⁻¹ and an areal capacitance of 603.93 mF cm⁻², corresponding to a 4.5‐fold increase over unmodified MK. This improvement is primarily associated with enhanced Na ⁺ availability and refined pore connectivity attributed to the presence of SO₄²⁻ anions. These findings demonstrate a viable route toward structural electrolytes for next‐generation energy‐storage‐integrated building materials, although further investigation under application scenarios is still required.

在胶凝材料中集成机械稳健性和离子电导率代表了一种有前途的策略，即用于储能集成建筑系统的多功能结构电解质。在这项研究中，用不同的钠盐（Na2SO4， NaCl和NaOH）修饰碱活化的偏高岭土（MK）地聚合物，以阐明凝胶结构演变，离子传输行为和电化学性能之间的关系。结果表明，钠盐的掺入显著提高了地聚合物电解质的离子电导率和电容性能。Na2SO4修饰样品（MK‐S）的离子电导率最高，为33.22 mS cm-1，面电容为603.93 mF cm-2，比未修饰的MK增加了4.5倍。这种改善是由于SO42-配位诱导的移动Na+浓度增加和优化的孔连性的协同作用。这些发现为下一代储能集成建筑材料提供了一条通向耐用结构固体电解质的可行途径。

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引用次数: 0

Ultra-high sensitivity biomass-based cement sensor utilizing three-dimensional conductive luffa sponge 利用三维导电丝瓜海绵的超高灵敏度生物质水泥传感器

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

Cement & concrete composites

Pub Date : 2025-11-25 DOI: 10.1016/j.cemconcomp.2025.106416

Lu Yang , Yifan Hou , Hanqi Ji , Kuo Li , Qiuying Zhao , Chen Wang , Haiyan He , Huajie Huang , Hongqiang Chu , Feifei Zhao

Biomass-based conductive cements with high mechanical strength and piezo-resistivity are emerging as promising candidates for constructing compatible and embedded pressure sensors in smart infrastructure systems. However, the inherently rigid nature of cement poses a significant challenge in achieving both high sensitivity and low detection limits, limiting their widespread application. Herein, we develop a novel luffa sponge/cement composite with ultra-high sensitivity and low detection limit by employing a “hard–soft” integration strategy. Specifically, luffa sponge (LS) is firstly attached with multi-walled carbon nanotubes (MWCNTs) through in-situ polymerization of dopamine, forming a conductive yet flexible three-dimensional network (LS-M). The subsequent incorporation of soft LS-M framework into rigid cement matrix can facilitate efficient stress transfer and continuous electron pathways upon small pressure, leading to boosted piezoresistive performance. The proposed sensor demonstrates a giant sensitivity up to 12.3 MPa⁻¹, ultra-low detection limit of 188 Pa, exceptional linearity (R² > 0.98) and remarkable stability over 160 loading/unloading cycles (6.0 MPa). Additionally, a further hydrophobic surface coating extends its applicability to humid and underwater environments, validating its capability in complex scenarios. This work presents a promising approach for the development of biomass-based conductive cements for high-performance pressure sensor in smart infrastructure.

具有高机械强度和压电阻率的生物质导电水泥正在成为智能基础设施系统中构建兼容和嵌入式压力传感器的有希望的候选者。然而，水泥固有的刚性特性对实现高灵敏度和低检测限提出了重大挑战，限制了它们的广泛应用。在此，我们采用“软硬”集成策略开发了一种具有超高灵敏度和低检测限的新型丝瓜海绵/水泥复合材料。具体来说，丝瓜海绵（LS）首先通过多巴胺的原位聚合与多壁碳纳米管（MWCNTs）连接，形成导电且柔性的三维网络（LS- m）。随后将软LS-M框架掺入刚性水泥基体中，可以促进小压力下有效的应力传递和连续的电子路径，从而提高压阻性能。该传感器具有高达12.3 MPa−1的超高灵敏度，188 Pa的超低检测限，出色的线性度（R2 > 0.98）和超过160个加载/卸载循环（6.0 MPa）的卓越稳定性。此外，进一步的疏水表面涂层扩展了其在潮湿和水下环境中的适用性，验证了其在复杂情况下的能力。这项工作为智能基础设施中高性能压力传感器的生物质导电水泥的开发提供了一种有前途的方法。

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引用次数: 0

Strength recovery mechanism in cement pastes modified with superhydrophobic silica fume: delayed pozzolanic activation and microstructural densification 超疏水硅灰改性水泥浆强度恢复机制：延迟火山灰活化和微观结构致密化

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

Cement & concrete composites

Pub Date : 2025-11-24 DOI: 10.1016/j.cemconcomp.2025.106409

Linjing Cui , Tengfei Xiang , Shuoshuo Chen , Shunquan Zhang , Minglei Guo , Zhong Lv , Hui Rong , Depeng Chen

Superhydrophobic silica fume (SSF) holds significant potential for enhancing the durability of cement-based materials in corrosive environments. Nevertheless, the trade-off between hydrophobicity and mechanical performance remains a critical challenge. SSF enhances the anti-corrosion performance of cement-based materials but reduces their early strength. This study reveals SSF's unique strength recovery mechanism: The alkaline environment progressively hydrolyzes the grafted silane layers, as directly evidenced by XPS, which shows a 13.06 % decrease in C-C/C-H bonds and a concurrent 10.81 % increase in Si—O—Si networks over 7 d. This alkaline hydrolyzes enables a delayed pozzolanic reaction, narrowing the gap in Ca(OH)₂ consumption from 1.8 % (3 d) to 1.0 % (56 d) in a simulated system and driving a more than twofold increase in Q₃ content in cement paste. Consequently, this delayed pozzolanic reaction underlies the observed strength recovery, effectively narrowing the compressive strength gap to 7.5 % at 56 d. This study confirms that the hydrophobic modification only temporarily suppresses reactivity, enabling a unique self-recovery mechanism that reconciles early-stage durability with long-term strength.

超疏水硅灰（SSF）在增强水泥基材料在腐蚀性环境中的耐久性方面具有巨大的潜力。然而，在疏水性和机械性能之间的权衡仍然是一个关键的挑战。SSF提高了水泥基材料的抗腐蚀性能，但降低了水泥基材料的早期强度。本研究揭示了SSF独特的强度恢复机制：XPS直接证明，碱性环境会逐渐水解接枝的硅烷层，在7天内，C-C/C-H键减少13.06%，同时Si-O-Si网络增加10.81%。这种碱性水解可以延迟火山灰反应，将模拟系统中Ca(OH)2消耗的差距从1.8 %（3天）缩小到1.0%（56天），并驱动水泥浆中Q3含量增加两倍以上。因此，这种延迟的火山灰反应是观察到的强度恢复的基础，在56 d时有效地将抗压强度差距缩小到7.5%。该研究证实，疏水改性只是暂时抑制反应性，实现了一种独特的自我恢复机制，可以协调早期耐久性和长期强度。

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引用次数: 0

Tip penetration test for rapid in-line assessment of static yield stress during 3D concrete printing process 在3D混凝土打印过程中，快速在线评估静态屈服应力的尖端渗透试验

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

Cement & concrete composites

Pub Date : 2025-11-24 DOI: 10.1016/j.cemconcomp.2025.106412

Ali Fasihi, Nicolas A. Libre

The static yield stress of printable cementitious materials is a critical parameter governing the shape stability and buildability of 3D printed concrete structures. Among various testing techniques, the penetration test has emerged as a promising method for in-situ measurement of static yield stress during printing process. However, the applicability of the penetration test for in-line monitoring of static yield stress remains limited due to the necessity for substantial material thickness. To address this challenge, this study proposes a novel tip penetration test, which enables static yield stress determination without the requirement for full cone submergence, thereby facilitating assessment of thin printed filaments while reducing the testing time.

The effects of key process parameters such as penetration speed (0.25 mm/s, 0.5 mm/s and 1 mm/s), cone surface condition (rough and smooth), and cone semi-angle (30°, 45° and 60°) on the accuracy of the tip penetration test results were systematically investigated by comparing the results with the standard vane rheometer test. Furthermore, a theoretical framework based on solid plasticity theory was proposed to convert the tip penetration test results to static yield stress. The optimum penetration speed was identified as 0.5 mm/s and smooth cones with semi-angles of 45° and 60° provided the best correlation with vane test results. The proposed theoretical model effectively estimated the static yield stress from tip penetration test results. The accuracy of the predictions was found to be highly sensitive to the selected failure criterion.

可打印胶凝材料的静态屈服应力是控制3D打印混凝土结构形状稳定性和可建造性的关键参数。在各种测试技术中，渗透测试已成为一种很有前途的印刷过程中静态屈服应力的原位测量方法。然而，由于需要较大的材料厚度，渗透试验在静态屈服应力在线监测中的适用性仍然有限。为了解决这一挑战，本研究提出了一种新的尖端侵彻测试方法，该方法可以在不需要完全浸入锥体的情况下进行静态屈服应力测定，从而在减少测试时间的同时便于对薄印刷细丝的评估。通过与标准叶片流变仪测试结果的对比，系统研究了侵透速度（0.25 mm/s、0.5 mm/s和1 mm/s）、锥体表面粗糙度（粗糙和光滑）、锥体半角（30°、45°和60°）等关键工艺参数对尖端侵透测试结果精度的影响。在此基础上，提出了一种基于固体塑性理论的理论框架，将尖端侵彻试验结果转化为静态屈服应力。确定最佳侵彻速度为0.5 mm/s，半角为45°和60°的光滑锥体与叶片试验结果相关性最好。提出的理论模型能有效地从尖端侵彻试验结果中估计出静态屈服应力。发现预测的准确性对所选择的失效准则高度敏感。

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引用次数: 0

Advancing energy savings and CO2 emission reductions in lightweight concrete with bio-based polyurethane phase change material for sustainable building applications 推进节能和二氧化碳减排的轻质混凝土与生物基聚氨酯相变材料的可持续建筑应用

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

Cement & concrete composites

Pub Date : 2025-11-22 DOI: 10.1016/j.cemconcomp.2025.106404

Muhammed Bayram , Ercan Aydogmuş , Osman Gencel , Abid Ustaoğlu , Ahmet Sarı , Gökhan Hekimoğlu , Selçuk Memiş , Hasbi Yaprak , Togay Ozbakkaloglu

Improving the energy efficiency of building materials is critical for reducing environmental impacts. This study develops and evaluates bio-based polyurethane composites (BPUCs) incorporating lauryl alcohol (LA) as a phase change material (PCM) for lightweight cementitious systems. The composites were synthesized from modified castor oil (MCO), commercial polyether polyol (CPP), and methylene diphenyl diisocyanate (MDI), and systematically characterized to assess their thermal, mechanical, microstructural, and environmental performance. Differential scanning calorimetry, thermogravimetric analysis, hardness, tensile, and thermal conductivity tests were performed, followed by outdoor thermal regulation testing using a full-scale cabin setup. Results show that increasing LA content improves bulk density (38.9–67.6 kg/m³), hardness (7.1–15.2), and thermal conductivity (0.026–0.038 W/m·K), while moderately reducing tensile strength (243–138 kPa) and strain (89–43 %). The optimized composite, BPUC-LA-6, achieved a latent heat storage of 127.8 J/g and enhanced thermal stability, with activation energy increasing from 108.47 to 164.13 kJ/mol. When incorporated into lightweight cementitious composites (BLWC3), the system reduced peak surface temperatures by up to 6.5 °C and maintained nighttime warmth by approximately 2 °C, confirming its effective thermal energy storage behavior. Energy simulations across different Turkish climate zones indicated heating energy reductions up to 60 % in severe climates, accompanied by proportional decreases in CO₂ emissions. The economic analysis showed annual savings between $0.65 and $4.39 per square meter depending on the heating source, with a payback period of 2–15 years. This work presents a scalable bio-based polyurethane–PCM system that integrates renewable materials with high PCM loading, offering a practical route to energy-efficient and low-carbon building materials.

提高建筑材料的能源效率对于减少对环境的影响至关重要。本研究开发并评估了将十二烷基醇（LA）作为轻质胶凝系统相变材料（PCM）的生物基聚氨酯复合材料（BPUCs）。以改性蓖麻油（MCO）、商业聚醚多元醇（CPP）和亚甲基二苯基二异氰酸酯（MDI）为原料合成了复合材料，并对其进行了热性能、力学性能、微观结构和环境性能的系统表征。进行了差示扫描量热法、热重分析、硬度、拉伸和导热性测试，随后进行了使用全尺寸座舱设置的室外热调节测试。结果表明：增加LA含量可提高材料的容重（38.9 ~ 67.6 kg/m3）、硬度（7.1 ~ 15.2）和导热系数（0.026 ~ 0.038 W/m·K），但可适度降低抗拉强度（243 ~ 138 kPa）和应变（89 ~ 43%）。优化后的bpu - la -6复合材料的潜热蓄积量为127.8 J/g，热稳定性增强，活化能从108.47增加到164.13 kJ/mol。当加入轻质胶凝复合材料（BLWC3）时，该系统将峰值表面温度降低了6.5°C，并保持了大约2°C的夜间温度，证实了其有效的热能储存行为。跨越土耳其不同气候带的能源模拟表明，在恶劣气候条件下，供暖能耗减少高达60%，同时二氧化碳排放量也相应减少。经济分析显示，根据供暖来源的不同，每平方米每年可节省0.65美元至4.39美元，投资回收期为2-15年。这项工作提出了一种可扩展的生物基聚氨酯- PCM系统，该系统集成了可再生材料和高PCM负荷，为节能和低碳建筑材料提供了一条实用的途径。

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引用次数: 0

Design of sustainable cementitious systems incorporating layered double hydroxides with antimicrobial and photocatalytic properties 可持续胶凝系统的设计，包括具有抗菌和光催化性能的层状双氢氧化物

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

Cement & concrete composites

Pub Date : 2025-11-22 DOI: 10.1016/j.cemconcomp.2025.106408

Dominika Konarska , Olga Długosz , Izabela Klapiszewska , Adam Kubiak , Anna Parus , Agnieszka Ślosarczyk , Jan Fořt , Teofil Jesionowski , Robert Černý , Marcin Banach , Łukasz Klapiszewski

Developing multifunctional cementitious composites that can address both structural and environmental challenges is essential for sustainable construction. In this study, Zn–Al layered double hydroxides (LDHs) modified with Zr⁴⁺, Ni²⁺, Ti⁴⁺, and Cu²⁺ were synthesized and incorporated as admixtures (0.25–1.0 wt%) into CEM I 42.5R and CEM II B-V 42.5R systems. XRD and morphological analyses confirmed the presence of well-defined LDH phases. The diffraction peaks, indexed to the R-3m space group, corresponded closely to the hydrotalcite reference pattern (JCPDS No. 89–0460) at the following angles: 11.71° (003), 23.52° (006), 34.47° (102), 39.29° (105), and 46.87° (108).

Zn–Al–Ti (ZAT) LDH demonstrated outstanding dual functionality, enabling the rapid photocatalytic degradation of metronidazole under UV-LED irradiation, with >95 % removal efficiency sustained over five reuse cycles. Additionally, ZAT exhibited complete antimicrobial activity at ≥0.75 wt%, preventing microbial colonization and enhancing long-term durability in humid or high-risk environments. Mechanical testing revealed that the Zn–Al–Zr (ZAZ) admixture significantly enhances compressive strength. In Series I, 0.25 wt% ZAZ achieved 34.6 MPa after 3 days and 56.8 MPa after 28 days, while 1.0 wt% ZAZ reached 32.1 and 64.5 MPa, respectively. In Series II, 0.75 wt% ZAZ reached 27.8 MPa at 3 days and 57.6 MPa at 28 days. Incorporating fly ash further improved performance by increasing porosity and internal light scattering.

These results demonstrate that LDH-modified cementitious composites are ideal for sewage pipelines, hospital wastewater channels, and other infrastructure that requires structural integrity and resistance to chemical and biological degradation.

开发能够解决结构和环境挑战的多功能胶凝复合材料对于可持续建筑至关重要。本研究合成了Zr4+、Ni2+、Ti4+和Cu2+改性的Zn-Al层状双氢氧化物（LDHs），并将其作为外加剂（0.25-1.0 wt%）掺入CEM I 42.5R和CEM II B-V 42.5R体系中。XRD和形态分析证实了LDH相的存在。衍射峰指向R-3m空间群，在11.71°（003）、23.52°（006）、34.47°（102）、39.29°（105）和46.87°（108）角度与水滑石参考模式（JCPDS 89-0460）密切对应。Zn-Al-Ti (ZAT) LDH表现出出色的双重功能，能够在UV-LED照射下快速光催化降解甲硝唑，并且在5个重复使用循环中具有95%的去除率。此外，ZAT表现出≥0.75 wt%的完全抗菌活性，防止微生物定植，提高在潮湿或高风险环境中的长期耐久性。力学试验表明，ZAZ - al - zr （ZAZ）掺合料显著提高了抗压强度。在系列1中，0.25 wt% ZAZ 3天后达到34.6 MPa， 28天后达到56.8 MPa，而1.0 wt% ZAZ分别达到32.1 MPa和64.5 MPa。在系列II中，0.75 wt%的ZAZ在3天达到27.8 MPa，在28天达到57.6 MPa。加入粉煤灰进一步提高了孔隙率和内部光散射性能。这些结果表明，ldh改性胶凝复合材料是污水管道、医院废水通道和其他要求结构完整性和耐化学和生物降解的基础设施的理想选择。

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引用次数: 0

Performance and mechanistic insights into cement systems modified with wastewater-recovered struvite 用废水回收的鸟粪石改性水泥体系的性能和机理

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

Cement & concrete composites

Pub Date : 2025-11-21 DOI: 10.1016/j.cemconcomp.2025.106406

Ugochukwu Ewuzie , Rupack R. Halder , Abdulkareem O. Yusuf , Abiodun A. Saka , Godwin I. Ogbuehi , Titus C. Egbosiuba , Damilola A. Daramola , Monday U. Okoronkwo

Struvite, the stable hydration product and primary strength phase in magnesium ammonium phosphate cement (MAPC), derived from wastewater treatment, has recently been utilized as a sustainable additive to Portland cement (PC). However, its impacts on cement hydration kinetics, pore refinement, rheology, and the mechanisms underlying these processes have not been comprehensively studied. This study developed Portland cement-struvite (PCS) systems by replacing PC with 3–20 % struvite (ST wt%: PCS3–PCS20) and evaluated these processes using isothermal calorimetry, 3D micro-computed tomography (μXCT), time-dependent rheometry, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), and the Krstulović-Dabić (K-D) model. The FTIR/XRD confirmed the coexistence of typical PC hydrates and struvite, while μXCT showed a 41.7 % porosity reduction for PCS10 after 28 days. Static yield stress (SYS) increased significantly with ST; PCS10 and PCS15 exhibited 200 % and 351 % higher SYS than the control after 30 min. Plastic viscosity decreased with increasing ST, extending placement windows and improving workability. At the optimal 10–15 % substitution rate, PCS10 (and PCS15) achieved a 5.6 % (6.7 %) and 72.1 % (86.8 %) increase in compressive and flexural strengths, respectively, after 28 days. The K–D modeling showed that all systems followed the NG–I–D mechanisms, with slightly declining rate constants and crystal growth index (n) as ST increased, indicating retardation and a shift in hydrate morphology. The PCS systems rely on filler effects and ST-mediated Ca²⁺ surface adsorption, promoting early flocculation and reducing porosity. The PCS systems require less water to maintain workability and mechanical strength, without needing flow-modifying additives.

鸟粪石是磷酸铵镁水泥（MAPC）中稳定的水化产物和初强相，来源于废水处理，最近被用作波特兰水泥（PC）的可持续添加剂。然而，其对水泥水化动力学、孔隙细化、流变学的影响以及这些过程背后的机制尚未得到全面研究。本研究用3-20%鸟粪石（ST wt%: PCS3-PCS20）代替PC，开发了波特兰水泥-鸟粪石（PCS）体系，并使用等温量热法、3D微计算机断层扫描（μXCT）、时间相关流变法、x射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和Krstulović-Dabić （K-D）模型对这些过程进行了评估。FTIR/XRD证实了典型的PC水合物与鸟粪石共存，而μXCT显示PCS10在28天后孔隙率降低了41.7%。静态屈服应力（SYS）随着温度的升高而显著增加；30分钟后，PCS10和PCS15的SYS分别比对照组高200%和351%。塑性粘度随温度的增加、放置窗口的延长和可加工性的提高而降低。在10-15%的最佳替代率下，PCS10（和PCS15）在28天后的抗压强度和抗弯强度分别提高了5.6%（6.7%）和72.1%（86.8%）。K-D模型表明，所有体系均遵循NG-I-D机制，随着ST的增加，速率常数和晶体生长指数(n)略有下降，表明水合物形态发生了阻滞和转变。PCS系统依靠填料效应和st介导的Ca2+表面吸附，促进早期絮凝和降低孔隙率。PCS系统需要更少的水来保持可加工性和机械强度，而不需要流动改性添加剂。

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引用次数: 0

Mechanism exploration of crack orientation influence on compression fracture behavior of ASR-affected concrete under multiaxial restraint using DIC analysis 基于DIC分析的裂缝取向对多轴约束下asr影响混凝土压缩断裂行为的影响机制探讨

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

Cement & concrete composites

Pub Date : 2025-11-21 DOI: 10.1016/j.cemconcomp.2025.106402

Xi Ji , Hyo Eun Joo , Zhaojing Li , Yuya Takahashi , Misato Fujishima , Taito Miura

Although crack anisotropy has been shown to significantly influence the compressive behavior of alkali–silica reaction (ASR)-deteriorated concrete, an insufficient understanding of the underlying mechanism hinders the accurate modeling of ASR-affected concrete under restrained conditions. This study investigates the relationship between compressive fracture process and pre-existing ASR-induced cracks in different orientations to address the critical gap regarding the influence of crack orientation. The specimens subjected to ASR under varying restraint conditions were tested under compression in different directions at comparable volumetric expansion levels. A digital image correlation analysis was employed to characterize the fracture behavior during loading. The loading-induced crack was observed to propagate along the pre-existing crack in parallel-crack-dominant specimens whereas they additionally formed perpendicular to the pre-existing cracks in orthogonal-crack dominant specimens. Furthermore, both qualitative and quantitative analyses illustrated a causal chain in which stress concentrations around the orthogonal cracks initiated minor perpendicular cracks under loading, which in turn facilitated crack bridging and induced an additional strength reduction in the orthogonal-crack-dominated specimens. Based on the analysis, the model for compressive strength reduction was improved with integrating the negative influence of orthogonal cracks. These findings can enhance the reliability of performance prediction for ASR-affected structures under complex restraint and loading conditions.

尽管裂缝各向异性已被证明对碱-硅反应（ASR）变质混凝土的压缩行为有显著影响，但对其潜在机制的理解不足，阻碍了在约束条件下对受ASR影响的混凝土进行准确建模。为了解决裂纹取向影响下的临界间隙问题，研究了不同取向的asr诱导裂纹与压缩断裂过程之间的关系。在不同约束条件下进行ASR试验的试样在不同方向的压缩下进行了比较的体积膨胀水平。采用数字图像相关分析来表征加载过程中的断裂行为。在平行裂纹优势试件中，加载诱导裂纹沿既有裂纹扩展，而在正交裂纹优势试件中，加载诱导裂纹垂直于既有裂纹扩展。此外，定性和定量分析都说明了一个因果链，其中正交裂缝周围的应力集中在加载下引发了较小的垂直裂缝，这反过来又促进了裂缝的桥接，并导致正交裂缝为主的试件的额外强度降低。在此基础上，考虑正交裂缝的负面影响，对抗压强度折减模型进行了改进。这些发现可以提高在复杂约束和载荷条件下受asr影响的结构性能预测的可靠性。

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