Service life estimation, failure mechanisms, and specifications of galvanic anodes for corroding reinforced concrete structures

IF 3.4 3区工程技术 Q2 CONSTRUCTION & BUILDING TECHNOLOGY

Materials and Structures Pub Date : 2024-12-02 DOI:10.1617/s11527-024-02536-2

Karthikeyan Manickam, Deepak K. Kamde, Radhakrishna G. Pillai

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Abstract

Cathodic protection using galvanic anodes is a proven technique to control or prevent corrosion of steel in reinforced concrete structures. However, huge variations have been observed in the properties of various galvanic anodes available in the concrete repair market and their resulting performance. This work assessed the performance of five commercially available galvanic anodes using an earlier developed Galvanic Anode Performance (GAP) test. In addition, a methodology to estimate the guaranteed minimum service life (SL_min) of galvanic anodes in concrete systems exposed to specific environmental conditions is developed. This methodology involves the determination of electrochemical capacity (i.e., total electrical charge drawn) of galvanic anodes and the corrosion rate of galvanic anodes using potentiostatic scans. It was found that the average SL_min of the five anodes tested under severe laboratory exposure conditions (Relative humidity of 100% and temperature of 25 ± 2 °C) ranged from about 3 months to 7 years – indicating huge variation in the quality of various galvanic anodes. The analysis of the physico-chemical characteristics of the encapsulating mortar of pristine and aged galvanic anodes showed that the average SL_min depends on the pH, activator content, total pore volume, and critical pore entry diameter of the encapsulating mortar and is irrespective of the mass of zinc. Also, the failure mechanisms of galvanic anodes observed during the GAP test are conceptualized and correlated to the properties of encapsulating mortar. Finally, a set of prescriptive and performance specifications for the selection of galvanic anode systems to achieve a target service life of repair is presented.

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腐蚀钢筋混凝土结构用电阳极的使用寿命估计、失效机制和规范

阴极保护是一种成熟的技术，用于控制或防止钢筋混凝土结构中钢的腐蚀。然而，在混凝土修复市场上可获得的各种阳极的性能及其产生的性能存在巨大差异。这项工作使用早期开发的电阳极性能（GAP）测试评估了五种市售电阳极的性能。此外，开发了一种估算暴露于特定环境条件下混凝土系统中电阳极保证最小使用寿命（SLmin）的方法。该方法包括使用恒电位扫描测定电阳极的电化学容量（即总电荷）和电阳极的腐蚀速率。研究发现，在恶劣的实验室暴露条件下（相对湿度为100%，温度为25±2°C），五种阳极的平均寿命从3个月到7年不等，这表明各种阳极的质量差异很大。对原始和老化阳极包封砂浆的理化特性分析表明，平均SLmin取决于包封砂浆的pH值、活化剂含量、总孔容和临界进孔直径，与锌的质量无关。同时，对GAP试验中观察到的阳极破坏机制进行了概念化，并将其与包封砂浆的性能相关联。最后，提出了一套规范和性能规范，用于选择电阳极系统，以实现修复的目标使用寿命。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Materials and Structures 工程技术-材料科学：综合

CiteScore

6.40

自引率

7.90%

发文量

222

审稿时长

5.9 months

期刊介绍： Materials and Structures, the flagship publication of the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM), provides a unique international and interdisciplinary forum for new research findings on the performance of construction materials. A leader in cutting-edge research, the journal is dedicated to the publication of high quality papers examining the fundamental properties of building materials, their characterization and processing techniques, modeling, standardization of test methods, and the application of research results in building and civil engineering. Materials and Structures also publishes comprehensive reports prepared by the RILEM’s technical committees.