Abstract With the growing demand for sustainability and rapid development of nanotechnology, nanocellulose materials extracted from natural plants have attracted great attention. The incorporation of nanocellulose materials leads to a change in viscosity and yield stress on ultra-high performance concrete (UHPC). Rheological parameters affect the mechanical strength and steel fiber distribution of UHPC significantly. Therefore, it is essential to adjust the matrix rheology within an appropriate range through nanocellulose materials. This study aims to propose a novel method to optimize steel fiber distribution and mechanical properties of UHPC by adjusting the matrix rheology with cellulose nanofibers (CNFs) suspensions. The relationship among CNF concentration, steel fiber distribution, and the mechanical properties of UHPC was established. Test results showed that the failure mode of UHPC containing CNFs changed from single cracking to multiple cracking, accompanied by 11–23% enhancement in tensile strength. With the increase of CNF concentrations, the probability density distribution functions of steel fiber orientation showed the trend toward the distribution with a larger inclination. The addition of CNF suspensions effectively reduced the number of steel fibers settling to the bottom of the specimens. Scanning electron microscopy analyses demonstrated that the nanoscale reinforcement by CNFs was conducive to improving the mechanical properties of UHPC.

中文翻译：

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使用纤维素纳米纤维调节超高性能混凝土的基体流变学和力学性能

摘要 随着人们对可持续性的需求不断增长和纳米技术的快速发展，从天然植物中提取的纳米纤维素材料引起了人们的广泛关注。纳米纤维素材料的加入导致超高性能混凝土 (UHPC) 的粘度和屈服应力发生变化。流变参数显着影响 UHPC 的机械强度和钢纤维分布。因此，有必要通过纳米纤维素材料将基体的流变性调节到合适的范围内。本研究旨在提出一种通过纤维素纳米纤维 (CNF) 悬浮液调节基体流变性来优化 UHPC 钢纤维分布和机械性能的新方法。CNF浓度、钢纤维分布、建立了UHPC的力学性能。测试结果表明，含有 CNF 的 UHPC 的失效模式从单一开裂转变为多个开裂，同时​​拉伸强度提高了 11-23%。随着CNF浓度的增加，钢纤维取向的概率密度分布函数呈现出向更大倾角分布的趋势。CNF 悬浮液的添加有效地减少了沉降到试样底部的钢纤维的数量。扫描电子显微镜分析表明，CNFs 的纳米级增强有利于提高 UHPC 的机械性能。伴随着 11-23% 的抗拉强度增强。随着CNF浓度的增加，钢纤维取向的概率密度分布函数呈现出向更大倾角分布的趋势。CNF 悬浮液的添加有效地减少了沉降到试样底部的钢纤维的数量。扫描电子显微镜分析表明，CNFs 的纳米级增强有利于提高 UHPC 的机械性能。伴随着 11-23% 的抗拉强度提高。随着CNF浓度的增加，钢纤维取向的概率密度分布函数呈现出向更大倾角分布的趋势。CNF 悬浮液的添加有效地减少了沉降到试样底部的钢纤维的数量。扫描电子显微镜分析表明，CNFs 的纳米级增强有利于提高 UHPC 的机械性能。