Influence of hydraulic pressure on pore structure evolution and chloride transport in concrete

IF 1.8 4区工程技术 Q3 CONSTRUCTION & BUILDING TECHNOLOGY

Magazine of Concrete Research Pub Date : 2024-03-11 DOI:10.1680/jmacr.23.00283

Jie Chen, Jin Xia, Renjie Wu, Yu Peng

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Abstract

To study the influence of hydraulic pressure on pore structure evolution and chloride transport behavior in concrete, the mass transport depth, chloride concentration, and pore characteristics of specimens with different water-cement ratios were investigated using silver nitrate spraying, potentiometric titration, the mercury intrusion porosimetry (MIP) method, N2 adsorption method, and laser confocal microscopy. The results showed that chloride concentration increases as the hydraulic pressure and the water-cement ratio increase. As this hydraulic pressure increases, the difference between water and chloride ion transport distinctive characteristics becomes conspicuously pronounced, extending from 5.2 mm to 25.4 mm in distance. The hydraulic pressure changes the pore structure of the concrete, leading to a surge in the specific surface area, larger porosity, and average pore diameters. Notably, ink-bottle-type pores emerge prominently and the proportion of fine mesopores and capillary pores markedly rises after the application of hydraulic pressure. Furthermore, a relationship between chloride diffusion coefficient and hydraulic pressure is suggested. A relationship between the modified permeability coefficient and hydraulic pressure is constructed based on the mesoporous contribution β to express the hysteresis effect of chloride.

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水压对混凝土中孔隙结构演变和氯离子迁移的影响

为了研究水压对混凝土中孔隙结构演变和氯离子迁移行为的影响，采用硝酸银喷射法、电位滴定法、汞侵入孔隙测定法（MIP）、N2 吸附法和激光共聚焦显微镜研究了不同水灰比试样的质量迁移深度、氯离子浓度和孔隙特征。结果表明，氯化物浓度随着水压和水灰比的增加而增加。随着水压的增大，水和氯离子迁移特性之间的差异变得非常明显，距离从 5.2 毫米扩展到 25.4 毫米。水压改变了混凝土的孔隙结构，导致比表面积增大、孔隙率增大和平均孔径增大。值得注意的是，在施加水压后，墨水瓶型孔隙明显出现，细中孔和毛细孔的比例明显上升。此外，氯化物扩散系数与水压之间也存在关系。根据介孔贡献率 β 构建了修正渗透系数与水压之间的关系，以表达氯化物的滞后效应。

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来源期刊

Magazine of Concrete Research 工程技术-材料科学：综合

CiteScore

4.60

自引率

11.10%

发文量

102

审稿时长

5 months

期刊介绍： For concrete and other cementitious derivatives to be developed further, we need to understand the use of alternative hydraulically active materials used in combination with plain Portland Cement, sustainability and durability issues. Both fundamental and best practice issues need to be addressed. Magazine of Concrete Research covers every aspect of concrete manufacture and behaviour from performance and evaluation of constituent materials to mix design, testing, durability, structural analysis and composite construction.