Effect of Wollastonite Microfiber on Ultra-High-Performance Fiber-Reinforced Cement-Based Composites Based on Application of Multi-Scale Fiber-Reinforcement System
Effect of Wollastonite Microfiber on Ultra-High-Performance Fiber-Reinforced Cement-Based Composites Based on Application of Multi-Scale Fiber-Reinforcement System
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DOI：
10.3151/jact.13.332
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发表时间：
2015-06-01
影响因子：
2
通讯作者：
Mihashi, Hirozo
中科院分区：
文献类型：
--
作者：
Kwon, Sukmin;Nishiwaki, Tomoya;Mihashi, Hirozo
超高性能纤维增强水泥基复合材料(UHP-FRCCS)的发展是因为需要一种新型的、具有高吸能能力的通用材料。超高压碾压混凝土具有优异的抗裂性和较长的使用寿命，适合用于抗震设计。本研究提出了一种基于多尺度纤维增强体系的材料设计概念。在这种方法中，长而粗的长纤维与短而细的中纤维和超细纤维混合。这种大纤维、中细纤维和超细纤维的组合有望提高复合材料在拉伸下的力学性能。然而，仅由微纤维增强的水泥基复合材料的延展性在很大程度上是未知的。因此，在这项研究中，作者通过两个系列的试验评估了超细纤维是否改善了超高强度碾压混凝土的延性。采用针状矿物硅灰石作为超细纤维，用两种不同类型的钢纤维作为中观纤维和宏观纤维。首先，通过砂浆缺口梁的三点弯曲试验评价了增韧效果。其次，通过单轴拉伸试验研究了硅灰石超细纤维对共混多尺度纤维增强体系力学性能的影响。大纤维、中细纤维和硅灰石超细纤维的共混物表现出很强的增强特性。结果表明，硅灰石超细纤维增强复合材料的延性与超细纤维含量和纤维类型密切相关，细纤维、中细纤维和大纤维共混可制得高韧性的超高强度碾压混凝土。因此，本文提出的基于多尺度纤维增强体系的材料设计思想能够有效地提高超高强度碾压混凝土的延性，即使在单轴受拉的情况下也是如此。
The development of ultra-high-performance fiber-reinforced cement-based composites (UHP-FRCCs) was motivated by the need for a new and versatile material with high energy absorption capacity. With its excellent cracking resistance and consequent long life, UHP-FRCC is suitable for use in seismic design applications. The present study proposes a material design concept based on a multi-scale fiber-reinforcement system. In this approach, long, thick macrofibers are blended with short, thin mesofibers and microfibers. Such a combination of macrofibers, mesofibers, and microfibers is expected to enhance the mechanical properties of the composite under tension. However, the ductility of cement-based composites reinforced solely by microfibers is largely unknown. Therefore, in this study, the authors assessed whether microfiber improves the ductility of UHP-FRCC in two series of experiments. Wollastonite, which is a needle-shape mineral, is employed as a microfiber, and two different types of steel fibers are used as meso-and macrofibers. First, the enhanced toughness was evaluated in three-point bending tests on notched mortar beams. Second, the influence of wollastonite microfiber on the mechanical properties of the blended multi-scale fiber-reinforcement system was evaluated in uniaxial tension tests. Blends of macrofibers, mesofibers, and wollastonite microfibers exhibited strong reinforcement characteristics. The results indicate that the ductility of composites reinforced with wollastonite microfibers is highly dependent on the microfiber contents and type of fiber used and that blending of micro-, meso-, and macrofibers produces a highly ductile UHP-FRCC. Thus the material design concept based on the multi-scale fiber-reinforcement system proposed in this paper was shown to be effective in increasing the ductility of UHP-FRCC, even under uniaxial tension.