高温对钢纤维-聚乙烯醇纤维-CaCO<sub>3</sub>晶须多尺度纤维/水泥复合材料弯曲性能和微观结构的影响

李黎; 李宗利; 高丹盈; 曹明莉

doi:10.13801/j.cnki.fhclxb.20200907.001

高温对钢纤维-聚乙烯醇纤维-CaCO₃晶须多尺度纤维/水泥复合材料弯曲性能和微观结构的影响

doi: 10.13801/j.cnki.fhclxb.20200907.001

李黎^1, ,,
李宗利^1,,
高丹盈²,
曹明莉^3,

1.
西北农林科技大学　水利与建筑工程学院　旱区农业水土工程教育部重点实验室，杨凌 712100
2.
郑州大学　土木工程学院，郑州 450002
3.
大连理工大学　建设工程学部，大连 116024

基金项目: 中央高校基本科研业务费专项资金(Z109022067)；国家自然科学基金(51678111)

详细信息

通讯作者:
李黎，博士，副教授，研究方向为纤维混凝土　E-mail：drlili@vip.163.com

中图分类号: TB332
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- 被引次数: 0
出版历程
- 收稿日期: 2020-08-03
- 录用日期: 2020-09-03
- 网络出版日期: 2020-09-08
- 刊出日期: 2021-07-15

Influence of high temperature on flexural properties and micro structure of steel fiber-polyvinyl alcohol fiber-CaCO₃ whisker multi-scale fibers/cement composite

LI Li^{1
, ,},
LI Zongli^1
,,
GAO Danying²,
CAO Mingli^3
,

1.
Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education, College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100, China
2.
School of Civil Engineering, Zhengzhou University, Zhengzhou 450002, China
3.
Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024, China

摘要

摘要: 为促进钢纤维(SF)-聚乙烯醇(PVA)纤维-CaCO₃晶须(CW)多尺度纤维/水泥复合材料的工程应用，考察其抗火耐高温性能，本文研究了SF-PVA-CW多尺度纤维/水泥复合材料高温后的弯曲性能及其微观结构。研究发现：随温度升高，SF-PVA-CW多尺度纤维/水泥复合材料弯曲强度总体下降，但在500℃以下时下降缓慢，CW掺量为3vol%的SF-PVA-CW多尺度纤维/水泥复合材料弯曲强度有所提高；800℃及以上时，SF-PVA-CW多尺度纤维/水泥复合材料的弯曲强度急剧下降。采用JSCE SF4规定的等效弯曲强度评价弯曲韧性。随温度升高，SF-PVA-CW多尺度纤维/水泥复合材料的等效弯曲强度逐渐降低，500℃以下时掺加CW显著增强了SF对裂缝的控制能力，其中小挠度阶段的作用效果优于大挠度阶段。800℃以上时，等效弯曲强度急剧下降，其中大挠度阶段下降更为显著。借助数码相机、光学显微镜和SEM进行多尺度观测，揭示了高温对SF-PVA-CW多尺度纤维/水泥复合材料弯曲性能影响的微观机制。
- 晶须 /
- 水泥 /
- 纤维/混凝土 /
- 高温 /
- 弯曲强度 /
- 弯曲韧性 /
- 微观机制
Abstract: In order to promote the engineering application of steel fiber (SF)-polyvinyl alcohol (PVA) fiber-CaCO₃ whisker (CW) multi-scale fibers/cement composite, and investigate its fire resistance and high temperature resistance, the flexural properties and microstructure of the SF-PVA-CW multi-scale fibers/cement composite after high temperature were studied. The results show that with the increase of temperature, the residual flexural strength of the SF-PVA-CW multi-scale fibers/cement composite decreases overall, but decreases slowly below 500℃ and the the SF-PVA-CW multi-scale fibers/cement composite with 3vol% CW still increase. The flexural strength decreases sharply at 800℃ and above. The equivalent flexural strength based on JSCE SF4 was used to evaluate the flexural toughness. With the increase of temperature, the equivalent flexural strength of the SF-PVA-CW multi-scale fibers/cement composite decreases gradually. At the temperature up to 500℃, the addition of CW significantly enhances the crack restricting of SF, and the effect of small deflection stage is better than that of large deflection stage. The equivalent flexural strength decreases sharply at 800℃ or above, especially at large deflection stage. With the help of digital camera, optical microscope and SEM, the micro mechanism of the influence of high temperature on the flexural properties of the SF-PVA-CW multi-scale fibers/cement composite was revealed.
- whiskers /
- cement /
- fiber reinforced concrete /
- high temperature /
- flexural strength /
- flexural toughness /
- micro mechanism

HTML全文

图 1 四点弯曲试验方法

Figure 1. Test method of four-point flexural test

下载: 全尺寸图片幻灯片

图 2 SF-PVA-CW多尺度纤维/水泥复合材料高温后的弯曲强度

Figure 2. Flexural strength of SF-PVA-CW multi-scale fibers/cement composites after high temperatures

下载: 全尺寸图片幻灯片

图 3 SF-PVA-CW多尺度纤维/水泥复合材料高温后特定挠度处的等效弯曲强度

Figure 3. Equivalent flexural strength at specific deflection of SF-PVA-CW multi-scale fibers/cement composites after high temperatures

L/600=0.2 mm; L/150=0.8 mm; L/100=1.2 mm; L/50=2.4 mm

下载: 全尺寸图片幻灯片

图 4 数码相机采集的SF-PVA-CW多尺度纤维/水泥复合材料高温后截面形貌

Figure 4. Section morphologies of SF-PVA-CW multi-scale fibers/cement composites after high temperatures acquired by digital camera

下载: 全尺寸图片幻灯片

图 5 高温后光学显微镜下SF-PVA-CW多尺度纤维/水泥复合材料的微观结构

Figure 5. Microstructures of SF-PVA-CW multi-scale fibers/cement composites under optical microscope after high temperatures

下载: 全尺寸图片幻灯片

图 6 高温后SF-PVA-CW多尺度纤维/水泥复合材料的SEM图像

Figure 6. SEM images of SF-PVA-CW multi-scale fibers/cement composites after high temperatures

下载: 全尺寸图片幻灯片

表 1 原材料的基本性能

Table 1. Properties of raw materials

Raw material	Density/ (g·cm⁻³)	Size	Mechanical property	Origin
Cement	3.20	Specific surface area 356 m²/kg	—	Dalian Onoda Cement Co. Ltd.
Silica sand	2.65	Fineness modulus 1.9 Media sand	Moh’s hardness 7	Dalian
SF	7.8	Length 13 mm; Diameter 200 μm	Tensile strength ≥2 GPa; Elastic modulus 200–210 GPa	Bekaert
PVA	1.29	Length 6 mm; Diameter 31 μm	Tensile strength 1.1 GPa; Elastic modulus 41 GPa	Wanwei High-tech Material Co. Ltd., China
CW	2.86	Length 20–30 μm; Diameter 0.5–2 μm	Tensile strength 3–6 GPa; Elastic modulus 410–710 GPa	Shanghai Fengzhu Co. Ltd.
Notes: SF—Steel fiber; PVA—Polyvinyl alcohol fiber; CW—CaCO₃ whisker.

下载: 导出CSV

表 2 钢纤维(SF)-聚乙烯醇(PVA)纤维-CaCO₃晶须(CW)多尺度纤维/水泥复合材料的配比

Table 2. Proportions of steel fiber (SF)-polyvinyl alcohol (PVA) fiber-CaCO₃ whisker (CW) multi-scale fibers/cement composite

Group	Volume fraction/vol%			Fiber dosage/(kg·m⁻³)
Group	SF	PVA	CW	SF	PVA	CW
PC	0	0	0	0	0	0
CW/C	0	0	1	0	0	28.6
SF-PVA/C	1.50	0.5	0	117	6.45	0
SF-PVA-CW/C1	1.50	0.5	1	117	6.45	28.6
SF-PVA-CW/C2	1.25	0.5	2	117	6.45	57.2
SF-PVA-CW/C3	1.25	0.5	3	117	6.45	85.8

下载: 导出CSV

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