基于核磁共振技术的玄武岩-聚丙烯混杂纤维增强混凝土孔隙特征分析

黄观送; 苏丽; 薛翠真; 朱翔琛; 付勇; 叶付凯; 乔宏霞

基于核磁共振技术的玄武岩-聚丙烯混杂纤维增强混凝土孔隙特征分析

黄观送^{1, 2},
苏丽^{1, 2, ,},
薛翠真^{1, 2},
朱翔琛^{1, 2},
付勇^{1, 2},
叶付凯^{1, 2},
乔宏霞^{1, 2}

1.
兰州理工大学　土木工程学院, 兰州 730050
2.
甘肃省先进土木工程材料工程研究中心, 兰州 730050

基金项目: 国家自然科学基金(U21A20150)；甘肃省青年科学基金(23JRRA824)；甘肃省科技计划资助(23JRRA813)

详细信息

通讯作者:
苏丽，博士，副教授，硕士生导师，研究方向为混凝土耐久性　E-mail: suli_0527@163.com

中图分类号: TU528.1
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- 文章访问数: 91
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- 被引次数: 0
出版历程
- 收稿日期: 2024-03-18
- 修回日期: 2024-04-29
- 录用日期: 2024-05-09
- 网络出版日期: 2024-06-12

Analysis on pore characteristics of hybrid basalt-polypropylene fiber-reinforced concrete based on nuclear magnetic resonance technology

HUANG Guansong^{1, 2},
SU Li^{1, 2
, ,},
XUE Cuizhen^{1, 2},
ZHU Xiangchen^{1, 2},
FU Yong^{1, 2},
YE Fukai^{1, 2},
QIAO Hongxia^{1, 2}

1.
School of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, China
2.
Gansu Advanced Civil Engineering Materials Engineering Research Center, Lanzhou 730050, China

Funds: National Natural Science Foundation of China (U21A20150); Youth Science and Technology Foundation of Gansu Province (23JRRA824); Gansu Provincial Science and Technology Programme Grants (23JRRA813)

摘要

摘要: 采用核磁共振(Nuclear Magnetic Resonance，NMR)测试了玄武岩-聚丙烯混杂纤维混凝土(HBPRC)的孔隙特征，对比分析了玄武岩纤维(BF)和聚丙烯纤维(PF)以及二者混杂对HBPRC的抗压强度、孔隙率、孔径分布和曲折度的影响，并基于核磁共振T₂谱和孔隙结构分形理论对4个孔径区域的孔隙结构分形维数进行了量化。结果表明：随着BF的添加，T₂谱反映出适量的BF可以减小混凝土的孔隙率，而且有利于减小大孔体积占比；而随着PF含量增加，T₂谱面积增加，且混凝土内部孔隙有变大的趋势。掺入BF-PF混杂纤维对混凝土的孔隙特征会产生正协同作用，当BF和PF掺量均为0.05%时，协同作用最佳，与普通混凝土相比，抗压强度提高了3.52%、孔隙率降低了1.47%、曲折度提高了8.20%。凝胶孔体积占比增大了8.76%，大孔体积占比降低了5.30%，孔径分布得到优化。HBPRC的孔隙结构具有明显的分形特征，孔隙结构分形维数在过渡孔、毛细孔和大孔区域依次增加，此外，分形维数越大，抗压强度越大。通过微观分析认为，纤维在混凝土基体中的粘结状态和分布是影响HBPRC孔隙分形特征的主要原因。
- 玄武岩-聚丙烯混杂纤维混凝土 /
- 核磁共振 /
- 孔隙特征 /
- 抗压强度 /
- 孔隙结构分形维数
Abstract: The pore characteristics of hybrid basalt-polypropylene fiber-reinforced concrete (HBPRC) was tested by Nuclear Magnetic Resonance (NMR). The effects of basalt fiber (BF) and polypropylene fiber (PF) as well as their blends on the compressive strength, porosity, pore size distribution and tortuosity of HBPRC were analyzed comparatively. The fractal dimensions of the pore structure in four pore-size regions were quantified based on the T₂ spectra of NMR and pore structure fractal theory. The results show that with the addition of BF, the T₂ spectrum reflects that the appropriate amount of BF can reduce the porosity of concrete, and it is beneficial to reduce the percentage of large pore volume. But as the PF content increases, the T₂ spectral area increases and there is a tendency for the pores of the concrete to become larger. Incorporation of BF-PF hybrid fibers produces a positive synergistic effect on the pore characteristics of concrete. The synergistic effect is optimal when the dosage of both BF and PF is 0.05%, which improves the compressive strength by 3.52%, reduces the porosity by 1.47%, increases the volume percentage of gel pores by 8.76%, increases the tortuosity by 8.20%, and reduces the volume percentage of large pores by 5.30%, and optimizes the distribution of pore size, as compared with ordinary concrete. There are obvious fractal characteristics in the pore structure of HBPRC, and the fractal dimensions of the pore structure of HBPRC increases sequentially in the region of transition pores, capillary pores, and large pores. In addition, the larger the fractal dimension, the greater the compressive strength. It is concluded from the microscopic analysis that the bonding state and distribution of fibers in the concrete matrix are the main reasons affecting the pore fractal characteristics of HBPRC.
- basalt-polypropylene hybrid fiber reinforced concrete /
- nuclear magnetic resonance /
- pore characteristics /
- compressive strength /
- fractal dimension of the pore structure

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图 1 BF和PF外观形貌

Figure 1. Morphology of BF and PF

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图 2 MesoMR12-060H-I 岩石微观孔隙结构分析与成像系统

Figure 2. MesoMR12-060H-I Rock microscopic pore structure analysis and imaging system

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图 3 核磁共振试验样品制备

Figure 3. Preparation of the NMR samples

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图 4 抗压试件破坏形态

Figure 4. Failure modes of compression specimen

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图 5 28 d HBPRC抗压强度

Figure 5. Compressive strength test results of 28 d HBPRC

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图 6 (a) PF断裂形貌；(b) 纤维搭接；(c) BF-PF三维纤维网

Figure 6. (a) PF fracture morphology; (b) Fibers overlap; (c) Three-dimensional bearing fiber mesh of BF-PF

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图 7 单掺BF试件横向弛豫时间分布

Figure 7. Transverse relaxation-time distribution of single doped BF specimen

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图 8 单掺PF试件弛豫时间分布

Figure 8. Transverse relaxation-time distribution of single doped PF specimen

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图 9 HBPRC横向弛豫时间分布

Figure 9. Transverse relaxation-time distribution of HBPRC

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图 10 HBPRC的孔隙率

Figure 10. Porosity of HBPRC

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图 11 HBPRC的孔径分布

Figure 11. Pore size distribution of HBPRC

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图 12 HBPRC的曲折度

Figure 12. Tortuosity of HBPRC

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图 13 HBPRC横向弛豫时间与分形特征的关系

Figure 13. Relationship between transverse relaxation time and fractal characteristics of HBPRC

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图 14 不同孔隙的HBPRC的孔隙结构分形维数

Figure 14. Fractal dimension of pore structure of HBPRC with different pores

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图 15 纤维与混凝土基体粘结

Figure 15. Bonding between fibers and concrete matrix

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图 16 纤维在HBPRC中的分布

Figure 16. Distribution of fibers in HBPRC

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图 17 HBPRC抗压强度与孔隙结构分形维数的关系

Figure 17. Relationship between compressive strength and fractal dimension of pore structure of HBPRC

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表 1 胶凝材料和BF化学组成(wt%)

Table 1. Chemical composition of cementitious materials and BF (wt%)

Composition	SiO₂	Al₂O₃	Fe₂O₃	CaO	MgO
Cement	34.67	7.90	2.93	35.5	1.77
Fly Ash	50.77	22.68	5.64	5.98	1.74
BF	51.4	15.4	9.8	9	5.7

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表 2 BF和PF的物理力学性能

Table 2. Physical and mechanical of BF and PF

Type	Density/(kg·m⁻³)	Tensile Strength/MPa	Elastic Modulus/GPa	Diameter/μm	Length/mm
BF	2.65	≥2400	≥40	15	18
PF	0.91	270	0.3	30	19

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表 3 玄武岩-聚丙烯混杂纤维混凝土(HBPRC)配合比

Table 3. Mix proportions of hybrid basalt-polypropylene fiber-reinforced concrete (HBPRC)

Mixtures	Mixture composition/(kg·m⁻³)
Mixtures	C	W	CA	S	FA	PBS	BF	PF
BF0PF0	320	160	1068	712	100	6.3	0	0
BF0.05PF0	320	160	1068	712	100	6.3	1.3	0
BF0.1PF0	320	160	1068	712	100	6.3	2.6	0
BF0PF0.05	320	160	1068	712	100	6.3	0	0.5
BF0PF0.1	320	160	1068	712	100	6.3	0	0.9
BF0.05PF0.05	320	160	1068	712	100	6.3	1.3	0.5
BF0.1PF0.05	320	160	1068	712	100	6.3	2.6	0.5
BF0.05PF0.1	320	160	1068	712	100	6.3	1.3	0.9
BF0.1PF0.1	320	160	1068	712	100	6.3	2.6	0.9
Notes: "C" refers to cement, "W" refers to water, "CA" refers to coarse aggregate, "S" refers to river sand, "FA" refers to fly ash, "PBS" refers to performance water reducer, "BF" refers to basalt fiber, "PF" refers to polypropylene fiber, "0", "0.05", "0.1" represent the fiber volume content of 0%, 0.05%, 0.1%, respectively

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表 4 HBPRC的横向弛豫T₂谱峰面积比例

Table 4. Transverse relaxation-time T₂ spectral peak area percentage of HBPRC

Mixtures	Peak 1/%	Peak 2/%	Peak 3/%	Peak 4/%
BF0PF0	62.60	13.91	10.18	13.28
BF0.05PF0	72.54	11.55	8.70	7.19
BF0.1PF0	61.79	13.66	10.07	14.46
BF0PF0.05	51.43	13.69	12.42	22.44
BF0PF0.1	56.05	13.77	10.25	19.92
BF0.05PF0.05	69.48	12.72	10.97	6.81
BF0.1PF0.05	64.08	13.52	9.44	12.94
BF0.05PF0.1	55.91	15.72	10.96	17.39
BF0.1PF0.1	65.80	14.44	12.14	7.60

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