硅酸盐学报

冻融与盐蚀耦合作用下混凝土的细观特征与损伤演化规律

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陈少杰 ¹ , 任建喜 ¹ , 刘浪 ² , 李玉根 ³ , 任翔 ¹ , 符强 ⁴

硅酸盐学报 | 研究论文 2024,52(11): 3524-3536

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硅酸盐学报 |研究论文 2024 , 52 (11) : 3524 -3536

冻融与盐蚀耦合作用下混凝土的细观特征与损伤演化规律

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陈少杰¹, 任建喜¹, 刘浪², 李玉根³, 任翔¹, 符强⁴

作者信息

^1．西安科技大学建筑与土木工程学院，西安 710054

^2．西安科技大学能源学院，西安 710054

^3．榆林学院建筑工程学院，陕西榆林 719000

^4．陕西省现代建筑设计研究院有限公司，西安 710021

通讯作者:

陈少杰（1989—），男，博士，讲师；

李玉根（1983—），男，博士，教授。

作者简介:

陈少杰（1989—），男，博士，讲师。

Mesoscopic Characteristics and Damage Evolution of Concrete Under Coupling Freeze-Thaw and Salt Erosion

Shaojie CHEN¹, Jianxi REN¹, Lang LIU², Yugen LI³, Xiang REN¹, Qiang FU⁴

Affiliations

^1.School of Architecture and Civil Engineering, Xi'an University of Science and Technology, Xi'an 710054, China

^2.School of Energy Engineering, Xi'an University of Science and Technology, Xi'an 710054, China

^3.School of Architecture Engineering, Yulin University, Yulin 719000, Shaanxi, China

^4.Shanxi Modern Architectural Design and Research Institute Co., Ltd, Xi'an 710021, China

Corresponding Author:

CHEN Shaojie (1989-), male, Ph.D., Lecturer. E-mail: csj@xust.edu.cn;

LI Yugen (1983-), male, Ph.D., Professor. liyugen@yulinu.edu.cn

CHEN Shaojie (1989-), male, Ph.D., Lecturer. E-mail: csj@xust.edu.cn

出版时间: 2024-11-20 doi: 10.14062/j.issn.0454-5648.20240005

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摘要

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通过快速冻融试验，结合X射线计算机断层成像（CT）扫描技术和三维重构分析，在细观尺度上研究了不同氯盐浓度环境与冻融作用下混凝土剥落深度、体积损失率、孔隙结构和CT值的变化规律。基于CT数据建立了混凝土的损伤演化模型，并与波幅和质量定义的损伤进行了对比分析。结果表明：冻融与盐蚀耦合作用下混凝土主要发生砂浆剥落破坏，剥落深度和体积损失率随冻融次数的增加而增大。冻融过程中混凝土的损伤由表及里，随着表面砂浆剥落，部分闭口孔逐渐转为开口孔，最终消失，试样孔隙率整体呈波动增大趋势。氯盐浓度对混凝土冻融损伤发展速度影响显著，随着氯盐浓度的增加，混凝土的剥落深度和体积损失率呈先增大后减小的趋势。混凝土的超声波波幅随冻融次数的增加逐渐减小，二者存在较好的指数关系。试验设计的4种浓度中，3.5%（质量分数）氯盐溶液中的混凝土冻融破坏最严重。基于CT数据定义的损伤演化模型与波幅和质量表征的损伤度线性关系良好，且与质量损失率吻合度更高，说明该模型较好地反映了混凝土的损伤演化过程。

关键词

冻融 / 盐蚀 / 混凝土 / 细观特征 / 扫描技术 / 损伤分析

Abstract

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Introduction

Concrete structures serving in cold regions are often affected by freeze-thaw damage, which is the main reason for the loss of durability in cold region concrete. Additionally, cold region concrete is also subject to salt erosion due to factors such as soil salinity and winter salt application. The coupled action of freeze-thaw and salt attack causes more severe damage to the internal structure of concrete materials, greatly impacting their service life. The deterioration of concrete durability under the coupled action of freeze-thaw and salt attack is primarily manifested as degradation of macroscopic properties such as mass, dynamic elastic modulus, and strength, accompanied by changes in the microstructure. The deterioration process is a complex physical-chemical process involving multiple scales. Merely focusing on the evolution of macroscopic properties often hinders a deep understanding of the degradation mechanisms. Therefore, it is of great significance to clarify the evolution process of microscopic features of concrete under the coupled action of freeze-thaw and salt attack, quantitatively characterize the damage evolution laws from the perspective of pore structure, spalling depth, and compactness, in order to gain a profound understanding of the coupling mechanism and degradation mechanisms of both phenomena.

Methods

Concrete specimens were prepared using volume-stable P·O 42.5 ordinary Portland cement, river sand with a fineness modulus of 2.5, and coarse aggregates ranging from 5 mm to 10 mm. The dimensions of the concrete specimens were 100 mm×100 mm × 100 mm. NaCl solutions with four different concentrations, namely 0%, 3.5%, 5.0%, and 8.0%, were used as the corrosive medium in the freeze-thaw process. A freeze-thaw cycling tests according to the fast freezing method specified in GB/T50082—2009.

Concrete specimens were scanned using a LightSpeed 64-layer helical CT scanner with a resolution of 512×512 pixels and an X-ray tube voltage of 120 kV. To prevent water evaporation and loss of moisture during CT scanning, the specimens were wrapped in plastic film. After obtaining the CT data, three-dimensional reconstruction analysis was performed to investigate microstructural parameters such as delamination depth, volumetric loss rate, pore structure, and CT value.

Results and discussion

The depth and volume of concrete spalling under the coupling effect of freeze-thaw and salt erosion gradually increase with the increase of freeze-thaw cycles, and the damage is mainly manifested as surface spalling. The degree of spalling in specimens with different concentrations of chloride salt solution is significantly different, increasing first and then decreasing with the increase of chloride salt concentration, and the spalling depth is the largest when the chloride salt concentration is 3.5%. The volume loss rate of concrete gradually increases with the increase of freeze-thaw cycles, and first increases and then decreases with the increase of chloride salt concentration. Among the four concentrations used in this experiment, the volume loss rate is the highest at a chloride salt concentration of 3.5%, followed by 5%, 8%, and 0%. The ultrasonic wave amplitude of concrete gradually decreases with the increase of freeze-thaw cycles, and there is a good exponential relationship between the two. The mass loss rate of concrete gradually increases with the increase of freeze-thaw cycles, and first increases and then decreases with the increase of concentration.

The coupling effect of freeze-thaw and salt erosion leads to dynamic changes in the pore structure of concrete, mainly occurring on the outer side of the specimens. With the increase of freeze-thaw cycles, the overall porosity shows a fluctuating increasing trend. With the aggravation of freeze-thaw damage, some closed pores gradually transform into open pores and then disappear with the peeling off of mortar. The damage evolution model based on the relative CT value definition has a good linear relationship with the damage characterization of amplitude and mass, and has a higher agreement with the mass loss rate. The damage degree of concrete gradually increases with the increase of freeze-thaw cycles, and first increases and then decreases with the increase of chloride salt concentration. A certain range of chloride salt concentration can accelerate the freeze-thaw damage of concrete, but when it exceeds this range, the development of damage is slowed down, and the concrete freeze-thaw damage degree reaches the maximum value at a chloride salt concentration of 3.5%.

Conclusions

Chloride salt has two effects on the freeze-thaw damage of concrete. On one hand, chloride salt increases the concentration difference between the inside and outside of the concrete pores during the freeze-thaw process, increases the liquid absorption rate of the specimen, and generates more pore ice during freezing, which accelerates the damage of concrete within a certain concentration range. On the other hand, the freezing point of chloride salt solution is lower than that of pure water. High concentration chloride salt solution has a slower freezing rate during the cooling process and a faster melting rate during the warming process. Compared with low concentration solution, the specimen has a shorter freezing time, which reduces the extent of concrete damage. Based on the analysis of indicators such as peeling depth, volume loss rate, amplitude, and mass loss rate in this study, it's found that a certain range of chloride salt concentration can accelerate the freeze-thaw damage of concrete, but the development rate of damage slows down when the range is exceeded. Among the four chloride salt concentrations used in this experiment, the concrete damage reaches the maximum value when the concentration is 3.5%.

Key words

freeze-thaw / salt erosion / concrete / mesoscopic characteristics / scanning technique / damage analysis

引用本文

陈少杰, 任建喜, 刘浪, 李玉根, 任翔, 符强. 冻融与盐蚀耦合作用下混凝土的细观特征与损伤演化规律. 硅酸盐学报, 2024 , 52 (11) : 3524 -3536 . DOI: 10.14062/j.issn.0454-5648.20240005

Shaojie CHEN, Jianxi REN, Lang LIU, Yugen LI, Xiang REN, Qiang FU. Mesoscopic Characteristics and Damage Evolution of Concrete Under Coupling Freeze-Thaw and Salt Erosion[J]. Journal of the Chinese Ceramic Society, 2024 , 52 (11) : 3524 -3536 . DOI: 10.14062/j.issn.0454-5648.20240005

基金

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国家自然科学基金(52268047)
陕西省自然科学基础研究计划(2024JC-YBQN-0610)
陕西省博士后科研项目(2023BSH EDZZ310)
陕西省“四主体一联合”地下结构抗震校企联合研究中心开放基金(KY2024-YB01)
榆林市科技计划项目(CXY-2022-157)

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2024年第52卷第11期

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文章信息

doi: 10.14062/j.issn.0454-5648.20240005

接收时间：2024-01-03
首发时间：2026-10-22
出版时间：2024-11-20

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出版历史

收稿日期：2024-01-03
修回日期：2024-02-03

基金

国家自然科学基金(52268047)

陕西省自然科学基础研究计划(2024JC-YBQN-0610)

陕西省博士后科研项目(2023BSH EDZZ310)

陕西省“四主体一联合”地下结构抗震校企联合研究中心开放基金(KY2024-YB01)

榆林市科技计划项目(CXY-2022-157)

作者信息

^1．西安科技大学建筑与土木工程学院，西安 710054

^2．西安科技大学能源学院，西安 710054

^3．榆林学院建筑工程学院，陕西榆林 719000

^4．陕西省现代建筑设计研究院有限公司，西安 710021

通讯作者:

陈少杰（1989—），男，博士，讲师；

李玉根（1983—），男，博士，教授。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20240005

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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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