Chloride erosion resistance of calcium formate incorporated cement mortar under chloride attack

•Calcium formate correlates adversely with chloride-induced-corrosion resistance of cement mortar.•The content of calcium formate influences corrosion of steel bar.•Calcium formate loosens internal structure of cement mortar after soaked in NaCl solution. Calcium formate has been widely added in con...

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Bibliographic Details
Published in:Construction & building materials 2022-01, Vol.314, p.125611, Article 125611
Main Authors: Ben, Xunqin, Jiang, Linhua, Guo, Ming-Zhi, Meng, Yuanyuan, Chen, Lei, Jin, Weizhun, Wang, Fei
Format: Article
Language:English
Subjects:
Accelerator
Calcium formate
Chloride ion erosion
Durability
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Summary:•Calcium formate correlates adversely with chloride-induced-corrosion resistance of cement mortar.•The content of calcium formate influences corrosion of steel bar.•Calcium formate loosens internal structure of cement mortar after soaked in NaCl solution. Calcium formate has been widely added in concrete as an accelerator to obtain a high early strength in civil engineering, such as shotcrete and concrete repairment. However, its effect on chloride ion erosion and steel bar corrosion under marine environments is elusive. In this study, rapid chloride migration and chloride ion titration methods were employed to investigate the effect of calcium formate on the chloride ion erosion in cement mortars. Electrochemical impedance spectroscopy and the loss weight ratio of rebar were measured to quantitatively characterize the corrosion extent of the steel bars. Furthermore, the relationship between chloride ion penetration and internal structures of the composite was established based on its pore structures characterized by means of mercury intrusion porosimetry. The crystalline phases and microstructures of the cement pastes were examined by XRD and SEM analyses, respectively. The results showed that calcium formate increased the formation of C2AH8 resulting in a significant increase in porosity and reducing the amount of chemical bound chloride ions inside, increasing the diffusion coefficient and content of chloride ion. Moreover, the increase in the number of internal pores allowed chloride ions to migrate easier in mortar and readily trigger corrosion of steel bars.
ISSN:0950-0618
1879-0526
DOI:10.1016/j.conbuildmat.2021.125611