Cement & concrete composites最新文献_第2页

Hydration mechanism and potential as solid-state electrolytes in sodium chloride-magnesium phosphate composite 氯化钠-磷酸镁复合材料作为固态电解质的水合机制和潜力

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-19 DOI: 10.1016/j.cemconcomp.2024.105862

Xiangrui Meng , Muhammad Riaz Ahmad , Mingzheng Zhu , Bing Chen , Liyan Wang

This study explores the feasibility of NaCl based magnesium phosphate cement (NaCl-MPC) composites as a solid electrolyte for energy storage applications by analyzing the physical, mechanical, hydration and electrochemical properties of composites. The results indicated that the incorporation of NaCl greatly improved the mechanical properties and ionic conductivity of composites, demonstrating enhanced electrochemical stability, making it a promising energy storage material. NaCl induced complex physical and chemical interactions within the MPC system by facilitating the filling of micropores and microcracks, providing the additional nucleation sites and converting intermediate products into struvite. NaCl also reacted chemically in the MPC system to produce small amounts of hazenite crystals. These effects ultimately led to the densification of the microstructure of MPC and significantly improved its mechanical properties. Generally, the improvement of ionic conductivity of solid electrolytes compromises their mechanical properties. However, the NaCl-MPC composites in this study showed significant improvement both in ionic conductivity and mechanical properties, highlighting their potential for advanced energy storage applications.

本研究通过分析复合材料的物理、机械、水合和电化学性能，探讨了将基于氯化钠的磷酸镁水泥（NaCl-MPC）复合材料作为固体电解质用于储能应用的可行性。结果表明，NaCl 的加入极大地改善了复合材料的机械性能和离子传导性，提高了电化学稳定性，使其成为一种前景广阔的储能材料。氯化钠促进了微孔和微裂缝的填充，提供了额外的成核位点，并将中间产物转化成了闪长岩，从而在 MPC 系统中引发了复杂的物理和化学相互作用。氯化钠还在 MPC 系统中发生化学反应，生成少量黑云母晶体。这些效应最终导致了 MPC 微观结构的致密化，并显著改善了其机械性能。一般来说，固体电解质离子电导率的提高会影响其机械性能。然而，本研究中的 NaCl-MPC 复合材料在离子传导性和机械性能方面都有显著改善，突出了其在先进储能应用方面的潜力。

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引用次数: 0

Hybrid effects of carbon nanotubes and nano-rubber on the mechanical properties and microstructure of oil well cement paste cured at different temperatures: Experimental studies and a micromechanical model 碳纳米管和纳米橡胶对不同温度下固化的油井水泥浆的力学性能和微观结构的混合效应：实验研究与微观力学模型

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-17 DOI: 10.1016/j.cemconcomp.2024.105842

Jiyun Shen , Yan Wang , Yongjin Yu , Pengcheng Fu , Mingliang Zhang , Longbang Qing , Rongwei Yang

A ductile oil well cement paste (OWCP) with lower autogenous shrinkage is of paramount importance to the integrity of cement sheath under downhole condition. Taking advantage of multiple experimental tests and a micromechanical model, the hybrid effects of nano-rubber (NR) and carbon nanotubes (CNTs) on the mechanical properties, autogenous shrinkage, hydration behavior and microstructure of OWCP were investigated in this study. Results show that the hybrid addition of NR and CNTs effectively enhances the mechanical properties and ductility of OWCP, 7-day tensile strengths of OWCP incorporated with 4 wt% NR and 0.04 wt% (N4C4) cured at 30 °C, 60 °C and 90 °C exhibit 1.4%, 13.7%, 13.0% strength gain with respect to those of plain OWCP (P) at the similar curing temperature; T/E ratios (tensile strength/Young’s modulus) of 7-day N4C4 cured at 30 °C, 60 °C and 90 °C exhibit 82.3%, 39.3% and 40.8% increase as compared to that of P at the similar curing temperature; the hybrid addition of NR and CNTs suppresses the autogenous shrinkage of OWCP, leading to about 31.9%, −12.8%, and 20.8% reduction of 72-hour autogenous shrinkage of OWCP at 30 °C, 60 °C and 90 °C, respectively. The developed micromechanical model is capable of well quantifying the hybrid effects of NR and CNTs on the mechanical/poroelastic properties of OWCPs. The present work is anticipated to shed light on the development of a ductile OWCP with lower autogenous shrinkage under harsh downhole conditions.

自生收缩率较低的韧性油井水泥浆（OWCP）对于井下条件下水泥护套的完整性至关重要。本研究利用多种实验测试和微观力学模型，研究了纳米橡胶（NR）和碳纳米管（CNTs）对 OWCP 的力学性能、自生收缩、水化行为和微观结构的混合影响。结果表明，混合添加 NR 和 CNTs 能有效提高 OWCP 的机械性能和延展性，在 30 ℃、60 ℃ 和 90 ℃ 下固化的含有 4 wt% NR 和 0.04 wt% (N4C4) 的 OWCP 的 7 天拉伸强度分别为 1.在相似的固化温度下，与普通 OWCP（P）相比，其强度分别增加了 4%、13.7% 和 13.0%；在 30 ℃、60 ℃ 和 90 ℃ 下固化 7 天的 N4C4 的 T/E 比（拉伸强度/杨氏模量）分别为 82.3%、39.3% 和 40.8%；NR 和 CNT 的混合添加抑制了 OWCP 的自生收缩，使 OWCP 在 30 ℃、60 ℃ 和 90 ℃ 下的 72 小时自生收缩率分别降低了约 31.9%、-12.8% 和 20.8%。所开发的微机械模型能够很好地量化 NR 和 CNT 对 OWCP 机械/波弹性特性的混合效应。本研究有望为开发在恶劣井下条件下具有较低自生收缩率的韧性 OWCP 提供启示。

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引用次数: 0

Effect of industrial multi-walled carbon nanotubes on the mechanical properties and microstructure of ultra-high performance concrete 工业多壁碳纳米管对超高性能混凝土力学性能和微观结构的影响

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-17 DOI: 10.1016/j.cemconcomp.2024.105850

Sijie Deng , Jie Fan , Biliang Yi , Jianfeng Ye , Gengying Li

To enhance the safety and functionality requirements of engineering structures, carbon nanotubes are used to improve the performance of concrete. However, their high cost limits their large-scale application. In this study, industrial multi-walled carbon nanotubes (IMWCNT) were employed to ultra-high performance concrete (UHPC) to achieve a balance between nanomodification and economy. The effects of different IMWCNT contents on the flowability, mechanical properties, and water resistance of UHPC were investigated. Moreover, the hydration products, microstructure, and fiber–matrix interface characteristics of UHPC specimens were analyzed using thermogravimetric analysis and scanning electron microscopy. The incorporation of appropriate amounts of IMWCNTs could effectively improve the mechanical properties and crack resistance of UHPC and partly prevent the infiltration of water into the matrix. Adding 0.1 wt% IMWCNTs resulted in optimal mechanical properties, and the flexural/compressive strengths of fiberless UHPC mortar and fibrous UHPC (2 vol% steel fibers) were increased by 6.7/5.2 % and 8.5/11.3 %, respectively. Microstructural analysis of the samples showed that uniformly dispersed IMWCNTs can enhance cement hydration and bridge the cracks at the microscale and nanoscale. In addition, incorporating an appropriate amount of IMWCNTs in UHPC reduced the porosity of its fiber–matrix interface and optimized steel fiber distribution in the matrix. Cost-benefit analyses results showed that although the addition of IMWCNTs increases the manufacturing cost of fibrous UHPC, their addition in moderate amounts (0.1 wt%) does not adversely affect the economic index due to the improvement in mechanical properties.

为了提高工程结构的安全性和功能性要求，碳纳米管被用来改善混凝土的性能。然而，碳纳米管的高成本限制了其大规模应用。本研究将工业多壁碳纳米管（IMWCNT）应用于超高性能混凝土（UHPC），以实现纳米改性与经济性之间的平衡。研究了不同 IMWCNT 含量对 UHPC 的流动性、力学性能和耐水性的影响。此外，还使用热重分析和扫描电子显微镜分析了 UHPC 试样的水化产物、微观结构和纤维-基质界面特征。结果表明，适量的 IMWCNTs 能有效改善 UHPC 的力学性能和抗裂性，并能在一定程度上防止水分渗入基体。添加 0.1 wt%的 IMWCNTs 可获得最佳力学性能，无纤维超高性能混凝土砂浆和有纤维超高性能混凝土（2 vol.%钢纤维）的抗弯/抗压强度分别提高了 6.7/5.2% 和 8.5/11.3%。样品的微观结构分析表明，均匀分散的 IMWCNTs 可以增强水泥的水化作用，并在微观和纳米尺度上弥合裂缝。此外，在 UHPC 中掺入适量的 IMWCNT 还能降低纤维-基体界面的孔隙率，优化钢纤维在基体中的分布。成本效益分析结果表明，虽然添加 IMWCNTs 会增加纤维状 UHPC 的制造成本，但适量添加（0.1 wt.%）IMWCNTs 并不会因其机械性能的改善而对经济指标产生不利影响。

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引用次数: 0

Effect of nano-silica on mechanical properties and microstructure of engineered geopolymer composites 纳米二氧化硅对工程土工聚合物复合材料机械性能和微观结构的影响

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-16 DOI: 10.1016/j.cemconcomp.2024.105849

Biqin Dong , Chenxi Liu , Eskinder Desta Shumuye , Yuanyuan Zhang , Hui Zhong , Guohao Fang

Engineered geopolymer composites (EGC) are promising alternatives to highly ductile cement-based composites, whereas effectively balancing the strength and ductility of most developed EGC mixes is challenging. This study systematically evaluated the feasibility of incorporating nano-silica (NS) particles to address the problem of balancing strength and ductility in EGC, aiming to develop EGC with extraordinary mechanical properties. The relationship between microstructure and mechanical properties of NS-EGC was studied via X-ray computed tomography (XCT) and backscattered electron microscopy (BSEM) tests, to gain an in-depth understanding of the obtained properties. Results indicate that NS-EGC mixes with superior compressive and tensile behaviour were successfully fabricated based on micromechanics design theory. The optimal NS content and particle size were 1 % and 15 nm, where the resulting composite outperformed all proposed EGC in terms of compressive strength (94 MPa), tensile strength (9.17 MPa) and tensile strain capacity (9.06 %). The mechanical properties of NS-EGC were strongly dependent on the pore structure, fibre orientation and fibre dispersion, where these microstructural effects can be modified by NS. This study provides a new approach to optimising the strength-ductility balance of EGC through nano-silica incorporation, offering the potential for broadening the application of EGC in high-performance structural materials.

工程土工聚合物复合材料（EGC）是高延展性水泥基复合材料的理想替代品，但有效平衡大多数已开发的 EGC 混合物的强度和延展性具有挑战性。本研究系统地评估了掺入纳米二氧化硅（NS）颗粒以解决 EGC 强度和延展性平衡问题的可行性，旨在开发出具有优异机械性能的 EGC。通过 X 射线计算机断层扫描（XCT）和背散射电子显微镜（BSEM）测试研究了 NS-EGC 的微观结构与机械性能之间的关系，以深入了解所获得的性能。结果表明，基于微机械设计理论，成功地制造出了具有优异压缩和拉伸性能的 NS-EGC 混合物。最佳的 NS 含量和粒度分别为 1%和 15 nm，由此制得的复合材料在抗压强度（94 兆帕）、抗拉强度（9.17 兆帕）和拉伸应变能力（9.06%）方面均优于所有建议的 EGC。NS-EGC 的机械性能与孔隙结构、纤维取向和纤维分散密切相关，而这些微观结构效应可通过 NS 加以改变。这项研究提供了一种新方法，通过加入纳米二氧化硅来优化 EGC 的强度-电导率平衡，为扩大 EGC 在高性能结构材料中的应用提供了可能。

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引用次数: 0

Exploiting Bacillus pseudofirmus and Bacillus cohnii to promote CaCO3 and AFt phase formation for stabilizing waste concrete fines 利用假芽孢杆菌和共生芽孢杆菌促进 CaCO3 和 AFt 相的形成以稳定废弃混凝土细料

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-15 DOI: 10.1016/j.cemconcomp.2024.105839

K. Kliková , P. Holeček , D. Koňáková , H. Stiborová , V. Nežerka

In this study, we explored the potential of microbiologically induced calcite precipitation (MICP) for enhancing the microstructural integrity of waste concrete fines (WCF). Traditionally, ureolytic bacteria, such as Sporosarcina pasteurii, have been widely used in MICP due to their ability to produce calcium carbonate via urea hydrolysis, but this process generates ammonia, raising environmental concerns. As an alternative, we employed the carbonic anhydrase pathway using Bacillus pseudofirmus and Bacillus cohnii to induce biomineralization without ammonia byproducts. We examined three types of WCF materials and found that samples containing gypsum facilitated the formation of AFt phases (ettringite/thaumasite crystals) when treated with these bacteria, significantly increasing WCF cohesion and forming strong conglomerates. Comparative analysis revealed that facultative anaerobes exploiting the carbonic anhydrase pathway outperformed ureolytic bacteria in strengthening the material. Investigations into pre-compaction and feather fiber reinforcement did not yield improvements in strength and stiffness.

在这项研究中，我们探讨了微生物诱导方解石沉淀（MICP）在增强废弃混凝土细料（WCF）微观结构完整性方面的潜力。传统上，尿素分解细菌（如巴氏芽孢杆菌）因能通过尿素水解产生碳酸钙而被广泛用于 MICP，但这一过程会产生氨，引起环境问题。作为一种替代方法，我们利用假芽孢杆菌（Bacillus pseudofirmus）和枯草芽孢杆菌（Bacillus cohnii）的碳酸酐酶途径来诱导生物矿化，而不产生氨副产品。我们研究了三种类型的 WCF 材料，发现含有石膏的样品经这些细菌处理后可促进 AFt 相（埃特林岩/白云石晶体）的形成，显著增加 WCF 的凝聚力并形成坚固的团块。比较分析表明，利用碳酸酐酶途径的兼性厌氧菌在增强材料强度方面优于尿解细菌。对预压实和羽毛纤维加固的研究并没有提高强度和刚度。

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引用次数: 0

Flexural post-cracking performance of macro synthetic fiber reinforced super workable concrete influenced by shrinkage-reducing admixture 受减缩外加剂影响的大体积合成纤维增强超强可加工混凝土的挠曲后开裂性能

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-13 DOI: 10.1016/j.cemconcomp.2024.105847

Jingjie Wei , Nima Farzadnia , Kamal H. Khayat

Most literature has focused on the effect of shrinkage-reducing admixture (SRA) in shrinkage mitigation resistance of concrete. This study aims to examine the impact of SRA on the efficiency of macro synthetic fibers (MSF) in enhancing the flexural post-cracking behavior of fiber-reinforced super workable concrete (FR-SWC). A comparative analysis of the influence of fiber combinations on the flexural post-cracking behavior of beams is also included. Results showed that a higher dosage of SRA, particularly at 5 % by mass of binder, had a noticeable negative impact on flexural post-cracking performance of beams while exhibiting positive effect on workability and shrinkage reduction. However, incorporating low dosages of SRA (1.25 % by mass of binder) did not have a significant impact on the ability of MSF. This was attributed to the reduction of the MSF-matrix bond strength caused by a significant delay in cement hydration. The characteristics of selected MSF type, including length and surface roughness had a positive effect on the post-cracking performance of FR-SWC, regardless of SRA dosage. The notched beams made with 100 % MSF_A outperformed those made with fiber combination of 25 % MSFA and 75 % MSF_B. Beams made with 100 % MSF_A showed 55 % higher residual flexural tensile strength, 49 % higher equivalent flexural tensile strength, 50 % higher fracture energy, and 35 % higher equivalent flexural strength ratio compared to beams made with fiber combination of 25 % MSF_A and 75 % MSF_B. Therefore, the negative effect of SRA on the flexural-post cracking behavior can be partial compensated by adjusting MSF content and combinations.

大多数文献都关注减缩外加剂（SRA）对混凝土抗收缩性的影响。本研究旨在考察 SRA 对大型合成纤维（MSF）在增强纤维增强超强工作性混凝土（FR-SWC）抗弯后开裂行为方面效率的影响。此外，还比较分析了纤维组合对梁弯曲后开裂行为的影响。结果表明，较高的 SRA 用量（尤其是粘结剂质量的 5%）对梁的挠曲开裂后性能有明显的负面影响，同时对工作性和收缩减少有积极作用。然而，添加低剂量的 SRA（粘结剂质量的 1.25%）对 MSF 的能力没有显著影响。这是因为水泥水化明显延迟导致 MSF-基质粘结强度降低。所选 MSF 类型的特征（包括长度和表面粗糙度）对 FR-SWC 的开裂后性能有积极影响，与 SRA 用量无关。使用 100% MSFA 制作的凹槽梁优于使用 25% MSFA 和 75% MSFB 纤维组合制作的凹槽梁。与使用 25% MSFA 和 75% MSFB 纤维组合制成的梁相比，使用 100% MSFA 制成的梁的残余抗弯强度提高了 55%，等效抗弯强度提高了 49%，断裂能提高了 50%，等效抗弯强度比提高了 35%。因此，通过调整 MSF 的含量和组合，可以部分弥补 SRA 对抗弯后开裂行为的负面影响。

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引用次数: 0

Effect of CuSO4 content and pH on the mechanical properties and antibacterial ability of copper-plated cement-based material CuSO4 含量和 pH 值对镀铜水泥基材料力学性能和抗菌能力的影响

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-13 DOI: 10.1016/j.cemconcomp.2024.105848

Hongqiang Chu , Weiling Chen , Yi Fang , Yunchao Liang , Baolin Long , Fengchen Zhang , Wenwei Li , Linhua Jiang

Microbial induced concrete corrosion (MICC) is the main deterioration mode of concrete corrosion in concrete wastewater transportation system. Protective coating is one of the commonly used microbial corrosion protection technologies for concrete. In this study, the effects of CuSO₄ concentration and pH value of electroless plating solution on the preparation of copper-plated hardened cement paste (HCP) were investigated, and the antibacterial properties of HCP surface were optimized by electroless copper plating. The main components of the coating were copper and its oxide particles. When HCP was plated at the CuSO₄ concentration of 10 g/L, the copper coating with high mass gain (0.3 %) and Vickers hardness (212.0 HV) was obtained. In addition, cubic copper structure constituted a compact copper coating HCP. The plating solution with pH of 9 was helpful to obtain the best quality gain and Vickers hardness of the coating. The microscopic morphology analysis showed that the coating had a relatively dense structure. Besides, antibacterial test indicated that copper-plated HCP had a significant improvement in antibacterial performance.

微生物诱发的混凝土腐蚀（MICC）是混凝土污水输送系统中混凝土腐蚀的主要恶化模式。保护涂层是常用的混凝土微生物腐蚀防护技术之一。本研究考察了 CuSO4 浓度和无电解镀液 pH 值对制备镀铜硬化水泥浆（HCP）的影响，并通过无电解镀铜优化了 HCP 表面的抗菌性能。镀层的主要成分是铜及其氧化物颗粒。当 HCP 的 CuSO4 浓度为 10 g/L 时，镀铜层的质量增益（0.3%）和维氏硬度（212.0 HV）都很高。此外，立方体铜结构构成了紧密的铜镀层 HCP。pH 值为 9 的电镀液有助于获得最佳的镀层质量增益和维氏硬度。显微形态分析表明，镀层具有相对致密的结构。此外，抗菌测试表明，镀铜 HCP 的抗菌性能显著提高。

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引用次数: 0

A novel all-solid-waste binder prepared by salt-alkali synergistic activation system constructed from phosphogypsum, soda residue and calcium carbide slag 利用磷石膏、碱渣和电石渣构建的盐碱协同活化体系制备的新型全固体废物粘合剂

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-10 DOI: 10.1016/j.cemconcomp.2024.105841

Di Wang , Zhaoyun Zhang , Weichao Guo , Jianyuan Li , Xuewei Li , Qingxin Zhao

Conventional alkali-activated slag materials apply strong industrial alkalis with high cost and potential corrosion risk. Alternatively, this study utilized industrial solid waste phosphogypsum, soda residue, and calcium carbide slag to construct a salt-alkali synergistic activated system. A new salt-alkali synergistic activation effect was formed by the SO₄²⁻ introduced by PG together with the Cl⁻ and OH⁻ provided by SR and CS, which promoted the hydration reaction. AFt, Friedel's salt, C-(A)-S-H, and other hydration products were generated and congregated, and a new all-solid-waste binder was created with 3d/28d strengths of 17.9/43.9 MPa, meeting the P·O 42.5 cement strength standard requirements. By conducting compressive strength and drying shrinkage tests on mortar and paste specimens with varying ratios, and employing XRD, TG-DTG, FTIR, and SEM-EDS analyses, the mechanical attributes of the binder were systematically assessed, and its hydration process was elucidated.

传统的碱活化炉渣材料使用强工业碱，成本高且具有潜在的腐蚀风险。而本研究利用工业固体废弃物磷石膏、苏打渣和电石渣构建了盐碱协同活化体系。PG 引入的 SO42- 与 SR 和 CS 提供的 Cl- 和 OH- 共同促进了水化反应，形成了新的盐碱协同活化效应。生成并聚集了 AFt、Friedel 盐、C-(A)-S-H 等水化产物，形成了新型全固态废料粘结剂，其 3d/28d 强度分别为 17.9/43.9 MPa，满足 P-O 42.5 水泥强度标准要求。通过对不同配比的砂浆和浆体试样进行抗压强度和干燥收缩试验，并采用 XRD、TG-DTG、FTIR 和 SEM-EDS 分析，系统地评估了该粘结剂的机械属性，并阐明了其水化过程。

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引用次数: 0

Layer interface characteristics and adhesion of 3D printed cement-based materials exposed to post-printing temperature disturbance 暴露于打印后温度干扰的 3D 打印水泥基材料的层界面特性和附着力

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-10 DOI: 10.1016/j.cemconcomp.2024.105837

Yi Zhang , Yaxin Tao , Jose R.A. Godinho , Qiang Ren , Zhengwu Jiang , Kim Van Tittelboom , Geert De Schutter

The layer interface, which is vital for the performance and longevity of 3D printed cement-based materials (3DPCM), is very sensitive to the environmental conditions because of the lack of formwork. Nevertheless, the current limited understanding of how temperature affects the layer interface has restricted the application of 3D printing in different construction scenarios. Here, we revealed the effects of temperature on the multi-scale phase distribution features of the layer interface through mercury intrusion porosimetry, X-ray computed tomography, nanoindentation and scanning electron microscopy with energy dispersive spectroscopy techniques. Additionally, the interlayer bond strength of 3DPCM was evaluated via the splitting tensile test. Small amplitude oscillation, surface roughness and isothermal calorimetry measurements were employed for an in-depth analysis of the mechanisms. Results indicate that an increase in temperature post-printing reduces the discrepancies in aggregate volume fraction between the layer interface and bulk matrix due to the increasing structuration rate and the amount of cement paste at the interface due to the reduced settlement of aggregates. The porosity difference between the layer interface and bulk matrix decreased with increasing temperature due to the pore size refinement by faster filling with hydrates. In addition, a more concentrated distribution of atomic ratios and elastic modulus of hydrates were observed at the layer interface of 3DPCM hardened at higher temperatures. Increased curing temperature improves the interlayer bond strength of 3DPCM owing to the enhanced aggregate interlocking, reduced porosity and improved high-density CSH content.

层界面对三维打印水泥基材料（3DPCM）的性能和寿命至关重要，但由于缺乏模板，层界面对环境条件非常敏感。然而，由于目前对温度如何影响层界面的了解有限，限制了 3D 打印在不同建筑场景中的应用。在此，我们通过汞侵入孔隙模拟法、X 射线计算机断层扫描、纳米压痕和扫描电子显微镜与能量色散光谱技术，揭示了温度对层界面多尺度相分布特征的影响。此外，还通过劈裂拉伸试验评估了 3DPCM 的层间结合强度。为深入分析其机理，还采用了小振幅振荡、表面粗糙度和等温量热测量法。结果表明，压印后温度的升高会减少层界面与块状基质之间的骨料体积分数差异，这是由于骨料的结构化率和界面上的水泥浆量都在增加，从而减少了骨料的沉降。随着温度的升高，层界面和大体积基质之间的孔隙率差异也会减小，这是由于水合物的快速填充使孔径细化。此外，在较高温度下硬化的 3DPCM 的层界面上观察到了更集中的水合物原子比和弹性模量分布。固化温度升高可提高 3DPCM 的层间粘结强度，原因是骨料交错性增强、孔隙率降低和高密度 CSH 含量提高。

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引用次数: 0

Enhancing fire resistance of lightweight high-performance cementitious composites using hollow microspheres 利用空心微球增强轻质高性能水泥基复合材料的耐火性能

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites

Pub Date : 2024-11-10 DOI: 10.1016/j.cemconcomp.2024.105845

Jingwei Yang , Hyunuk Kang , Jusung Yang , Junil Pae , Caijun Shi , Juhyuk Moon

Fire is detrimental to skyscrapers. Lightweight high-performance concrete (L-HPC) developed by combining lightweight microspheres and ultra-high-performance concrete binder is promising for future mega infrastructure projects. This study investigates the fire resistance of lightweight high-performance cementitious composites developed using hollow ceramic microspheres (HCMs) and hollow glass microspheres (HGMs) at different temperatures. Experimental results show that incorporating lightweight microspheres significantly increases the residual compressive strength of L-HPC by maintaining those of HGMs and HCMs groups at 92 % and 78 %, respectively, at 900 °C. Furthermore, these lightweight microspheres effectively mitigate thermal spalling and crack propagation in L-HPC. Microstructural analysis indicates that the lightweight microspheres facilitate steam-pressure release. The melting of HGMs realizes interconnections in the pore channel, which are subsequently strengthened by HGM and matrix-binder reactions. The HCMs feature perforated shells that provide inert and high-temperature-resistant steam channels. This study confirms that L-HPC developed using the abovementioned strategy exhibits excellent fire resistance.

火灾对摩天大楼有害无益。将轻质微球和超高性能混凝土粘结剂结合在一起开发的轻质高性能混凝土（L-HPC）在未来的大型基础设施项目中大有可为。本研究调查了使用空心陶瓷微球（HCMs）和空心玻璃微球（HGMs）开发的轻质高性能水泥基复合材料在不同温度下的耐火性能。实验结果表明，加入轻质微球可显著提高 L-HPC 的残余抗压强度，在 900 °C 时，HGMs 和 HCMs 组的残余抗压强度分别保持在 92% 和 78%。此外，这些轻质微球还能有效减轻 L-HPC 的热剥落和裂纹扩展。微结构分析表明，轻质微球有助于蒸汽压力释放。HGM 的熔化实现了孔道中的相互连接，随后通过 HGM 和基质粘结剂的反应加强了孔道。HCM 具有穿孔外壳，可提供惰性和耐高温的蒸汽通道。本研究证实，采用上述策略开发的 L-HPC 具有优异的耐火性能。

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引用次数: 0