Tailoring of steel fiber surface by coating cellulose nanocrystal for enhanced flexural properties of UHPC

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

Cement & concrete composites Pub Date : 2024-09-25 DOI:10.1016/j.cemconcomp.2024.105773

Jiang Du , Yuhuan Wang , Pengwei Guo , Weina Meng

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引用次数: 0

Abstract

Ultra-high-performance concrete (UHPC) is an advanced generation of cementitious composites with excellent compressive strength and durability. However, the relatively poor interfacial transition zone (ITZ) between steel fibers and UHPC matrix leads to insufficient flexural properties and hinders its further applications. This study proposed a cost-effective, sustainable, and highly reactive coating material, cellulose nanocrystals (CNCs), to densify the ITZ of steel fiber surfaces, thus enhancing the flexural properties of UHPC. Utilizing the Herschel-Bulkley model, the critical concentration of 1.0 % is determined for enabling uniform dispersion of CNCs, enhancing the coating performance and reliability. The performance of CNCs as coating materials was evaluated by flexural test of UHPC with CNCs-coated steel fibers, pull-off test, scanning electron microscope (SEM), atomic force microscope (AFM), energy-dispersive spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). Results showed that compared to UHPC with pristine steel fibers, the flexural strength and toughness of UHPC with CNCs-coated steel fibers were increased by up to 14 % and 18 %, because the single fiber pull-off energy was increased by 50 %. It can be attributed to the densified ITZ which is validated by the increased UHD C-S-H and HD C-S-H on ITZ. However, when the concentration of CNCs suspension (i.e., 1.5 %) exceeds the critical value, the CNCs coating film would stick the uniformly dispersed steel fibers together and then affect their distribution, thus reducing the mechanical performance of UHPC. This work provides a green and effective approach for promoting flexural properties and an in-depth understanding of CNCs coating mechanism.

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通过涂覆纤维素纳米晶调整钢纤维表面以增强超高强度混凝土的抗弯性能

超高性能混凝土（UHPC）是新一代水泥基复合材料，具有优异的抗压强度和耐久性。然而，钢纤维与超高性能混凝土基体之间的界面过渡区（ITZ）相对较差，导致抗折性能不足，阻碍了其进一步应用。本研究提出了一种具有成本效益、可持续发展和高活性的涂层材料--纤维素纳米晶体（CNCs），用于钢纤维表面 ITZ 的致密化，从而提高 UHPC 的抗弯性能。利用 Herschel-Bulkley 模型，确定了 1.0 % 的临界浓度可使 CNCs 均匀分散，从而提高涂层性能和可靠性。通过数控涂层钢纤维 UHPC 的弯曲试验、拉脱试验、扫描电子显微镜（SEM）、原子力显微镜（AFM）、能量色散光谱（EDS）和傅立叶变换红外光谱（FTIR），对数控涂层材料的性能进行了评估。结果表明，与含有原始钢纤维的 UHPC 相比，含有 CNCs 涂层钢纤维的 UHPC 的抗弯强度和韧性分别提高了 14% 和 18%，因为单根纤维的拉断能提高了 50%。这可以归因于 ITZ 的致密化，ITZ 上 UHD C-S-H 和 HD C-S-H 的增加也验证了这一点。然而，当 CNCs 悬浮液的浓度（即 1.5%）超过临界值时，CNCs 涂膜会将均匀分散的钢纤维粘在一起，进而影响其分布，从而降低 UHPC 的力学性能。这项研究为提高抗弯性能提供了一种绿色、有效的方法，同时也为深入了解 CNCs 涂覆机理提供了一种新的思路。

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来源期刊

Cement & concrete composites 工程技术-材料科学：复合

CiteScore

18.70

自引率

11.40%

发文量

459

审稿时长

65 days

期刊介绍： Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.