硅酸盐学报

导电超高性能混凝土的弯敏感知特性和荷载-挠度关系

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王艳 ¹^,² , 李奥阳 ¹ , 张少辉 ¹ , 郭冰冰 ²^,³ , 牛荻涛 ²^,³

硅酸盐学报 | 研究论文 2025,53(2): 416-427

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硅酸盐学报 |研究论文 2025 , 53 (2) : 416 -427

导电超高性能混凝土的弯敏感知特性和荷载-挠度关系

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王艳¹^,², 李奥阳¹, 张少辉¹, 郭冰冰²^,³, 牛荻涛²^,³

作者信息

^1．西安建筑科技大学材料科学与工程学院，西安 710055

^2．绿色建筑全国重点实验室，西安 710055

^3．西安建筑科技大学土木工程学院，西安 710055

作者简介:

王艳（1982—），女，博士，教授。

Bending Sensitive Characteristics and Load-Deflection Relationships of Conductive Ultra-High Performance Concrete

Yan WANG¹^,², Aoyang LI¹, Shaohui ZHANG¹, Bingbing GUO²^,³, Ditao NIU²^,³

Affiliations

^1.School of Materials Science and Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China

^2.State Key Laboratory of Green Building, Xi'an University of Architecture and Technology, Xi'an 710055, China

^3.School of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China

WANG Yan (1982-), female, Ph.D., Professor. E-mail: wangyanwjx@126.com

出版时间: 2025-02-20 doi: 10.14062/j.issn.0454-5648.20240025

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摘要

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碳纤维为工程结构的智能化建设提供了新途径，但其成本仍远高于其他纤维。利用废弃碳纤维（WCFs）制备了导电超高性能混凝土（C-UHPC），探究了C-UHPC的受弯性能、弯敏感知特性和荷载-挠度关系。结果表明：掺WCFs降低了C-UHPC的抗压强度。C-UHPC电阻率随WCFs掺量的增加而降低，当WCFs掺量为1%（体积分数）时，C-UHPC电阻率下降了99.89%，达到导电阈值。高掺量WCFs（>1%）会使C-UHPC韧性下降。弯曲应力下，C-UHPC的荷载-挠度曲线可分为弹性阶段、弯曲硬化阶段、破坏阶段。掺WCFs后C-UHPC具有受弯机敏特性，以峰值荷载为变化节点，峰前荷载的电阻曲线基本不发生波动，峰后荷载的电阻曲线快速上升。基于现有模型，建立了适用于C-UHPC的受弯荷载-挠度本构模型。最后，引入应力、应变灵敏度分析了不同WCFs掺量下C-UHPC弯曲应力、应变与电阻的关系。

关键词

超高性能混凝土 / 废弃碳纤维 / 导电性能 / 弯敏感知 / 荷载-挠度

Abstract

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Introduction

In modern society, the electricity is the foundation of all intelligent facilities. To realize the intelligent development of cementitious materials, electrical conductivity is one of the important directions for the future research of engineering structures and building materials. Of which, ultra-high performance concrete (UHPC) has been widely used in large-span building structures, tunnel and bridge structures, and repair and reinforcement projects, etc. If the conductive properties of UHPC are realized, and its self-sensing characteristics are given to achieve the demand of intelligent monitoring, it is of great theoretical significance and practical value to ensure the service safety of the building structure. It has reached a consensus at present that UHPC is modified by adding conductive materials to reduce the resistivity. However, conductive materials are expensive and difficult to achieve large-scale engineering applications. The use of waste carbon fibers (WCFs) can not only meet the performance requirements, but also reduce the preparation cost, improve the utilization rate of resources, and avoid environmental pollution. But at this stage, there is a lack of research on the influence of WCFs on the electrical conductivity of UHPC, and the relationship between electrical conductivity and load-deflection needs to be explored. Therefore, this paper took the electrical conductivity and bending performance of UHPC as the research point, and analyzed the bending sensitivity and load-deflection relationship of C-UHPC under different WCFs content. And the variation law between stress, strain and resistance was explored.

Methods

The UHPC with conductive properties was prepared by WCFs and steel fiber (SF), and the final mix ratio was determined by combining theoretical analysis and pre-experimental research. The water-binder ratio of C-UHPC was 0.16, and the content of WCFs was 0%, 0.5%, 1.0%, 1.5%, and 2% (in volume), respectively. Due to some differences between WCFs and virgin carbon fibers (VCFs), a comparative study of the two fibers was carried out by SEM, Raman spectroscopy, and contact angle. The compressive strength tests of C-UHPC cured for 1, 3, 7 d, and 28 d were carried out. The conductivity of C-UHPC was tested by four-electrode method (28 d). The bending sensitivity of C-UHPC mainly studied the relationship between stress, strain, and resistance under bending load. During the test, the load was automatically recorded by the stress sensor of the test machine, the deflection was measured by the bottom displacement meter of the specimen, and the resistance was measured by the external resistance box. After loading, the change values of load, deflection, and resistance were collected synchronously. Finally, SEM was used to observe the microscopic morphology of fibers and fiber-matrix interface in C-UHPC.

Results and discussion

Compared with VCFs, the surface of WCFs was smoother, but the wettability and graphitization degree were relatively poor. Compared with the reference group (WCFs content of 0%), the compressive strength of C-UHPC decreased after the addition of WCFs, which was attributed to the smaller bond force between the interface of WCFs and matrix. In addition, WCFs and SF were easily entangled with each other, and the positive synergism between fibers was weak. The resistivity of C-UHPC decreased with the increase of WCFs content, but when the content of WCFs was greater than or equal to 1%, C-UHPC reached the conductive threshold, that is, the effective lap probability between fibers satisfied the conductive path of electronic transmission. The main conductive pathways of WCFs in C-UHPC included overlapping, connecting cracks, and micropores. When C-UHPC was subjected to bending load, the specimen underwent uncracked, critical cracks, macroscopic cracks, and finally failure. Of which, the macro cracks were mainly axial cracks, which expanded from bottom to top.

A three-stage constitutive equation applicable to the C-UHPC bending load-deflection model was established with high prediction accuracy. When C-UHPC was subjected to bending load, the resistance changed, and this phenomenon indicated that C-UHPC had a bending sensitive property. Taking the peak load as the change node, the resistance curve of the pre-peak load decreased slightly, and the resistance curve of the post-peak load increased rapidly. This was because when C-UHPC was subjected to external loading, the internal microcracks and micropores were closed, resulting in a temporary increased and more complete conductive path, and the resistance decreased. After exceeding the peak load, the matrix gradually cracked, and the axial cracks expanded, interrupting most of the conductive paths, resulting in an increase in resistance. The stress sensitivity could be divided into two stages: first, the stress sensitivity decreased significantly first and then tends to be gentle with the increase of stress; second, the stress began to decrease after reaching the peak value, and the sensitivity increases. The Poisson's ratio was introduced to improve the formula for strain sensitivity, and the strain sensitivity perpendicular to the loading direction was obtained. The strain sensitivity decreased first and then increases with the increase of strain.

Results and discussion

The addition of WCFs could reduce the compressive strength of C-UHPC, but improved its conductivity. Under bending stress, the load-deflection curve of C-UHPC could be divided into elastic stage, bending hardening stage, and failure stage. After mixing with WCFs, C-UHPC took the peak load as the change node, and the resistance curve of the pre-peak load basically did not fluctuate, and the resistance curve of the post-peak load increased rapidly. When WCFs content was 1%, C-UHPC reached the conductive threshold, and continuing to increase fiber content had no significant effect on the resistivity. The sensitivity of C-UHPC decreased first and then increases with the increase of stress and strain.

Key words

ultra-high performance concrete / waste carbon fibers / conductive property / bending sensitivity / load-deflection

引用本文

王艳, 李奥阳, 张少辉, 郭冰冰, 牛荻涛. 导电超高性能混凝土的弯敏感知特性和荷载-挠度关系. 硅酸盐学报, 2025 , 53 (2) : 416 -427 . DOI: 10.14062/j.issn.0454-5648.20240025

Yan WANG, Aoyang LI, Shaohui ZHANG, Bingbing GUO, Ditao NIU. Bending Sensitive Characteristics and Load-Deflection Relationships of Conductive Ultra-High Performance Concrete[J]. Journal of the Chinese Ceramic Society, 2025 , 53 (2) : 416 -427 . DOI: 10.14062/j.issn.0454-5648.20240025

基金

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国家优秀青年科学基金(52222806)
国家自然科学基金面上项目(52078414)
陕西省杰出青年科学基金(2022JC-20)

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2025年第53卷第2期

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文章信息

doi: 10.14062/j.issn.0454-5648.20240025

接收时间：2024-01-09
首发时间：2026-10-22
出版时间：2025-02-20

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收稿日期：2024-01-09
修回日期：2024-03-21

基金

国家优秀青年科学基金(52222806)

国家自然科学基金面上项目(52078414)

陕西省杰出青年科学基金(2022JC-20)

作者信息

^1．西安建筑科技大学材料科学与工程学院，西安 710055

^2．绿色建筑全国重点实验室，西安 710055

^3．西安建筑科技大学土木工程学院，西安 710055

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240025

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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