Study on microstructural changes and acoustic emission characteristics during rust-induced expansion cracking in nano-metakaolin concrete

IF 3.9 3区工程技术 Q2 CONSTRUCTION & BUILDING TECHNOLOGY

Materials and Structures Pub Date : 2026-08-31 DOI:10.1617/s11527-026-03058-9

Wenjie Qi, Shiyi Zhang, Yingfang Fan, Dengfeng Li

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Abstract

Chloride ion permeation into concrete in marine environments initiates reinforcement corrosion, compromising structural integrity. Nano-metakaolin (NMK) effectively reduces concrete permeability. To investigate microstructural changes in NMK concrete under electric fields and the evolution of acoustic emission (AE) signals throughout corrosion stages, experiments monitored AE signals during accelerated corrosion-induced cracking of reinforced concrete under full immersion conditions. Characteristic AE signals at different stages were summarized, alongside an analysis of changes in hydration products. The findings indicate that NMK, rich in Si, Al, and other elements with pozzolanic activity, promotes the formation of hydration products. This improves the concrete microstructure, effectively impeding chloride ion migration within the matrix and thereby slowing reinforcement corrosion rates. After 48 h of electrification, the corrosion rate in the N5 group decreased by 59.80% compared to the N0 group. The morphology, quantity, and distribution of calcium silicate hydrate (C-S-H) gel, calcium hydroxide (CH) crystals, and Friedel’s salts were significantly influenced by NMK dosage. The relative content of C-S-H/AFt in the N5 group increased by 70.16% compared to the N0 group. As cement hydration progressed, NMK facilitated the transformation of large pores into smaller ones. The total void volume in the N5 group decreased by 21.97% compared to the N0 group. NMK can delay concrete crack formation, reduce the overall energy release rate, effectively inhibit shear crack development, and promote the stable propagation of tensile cracks.

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纳米偏高岭土混凝土锈蚀膨胀开裂微结构变化及声发射特性研究

在海洋环境中，氯离子渗透到混凝土中会引起钢筋腐蚀，损害结构的完整性。纳米偏高岭土（NMK）可有效降低混凝土渗透性。为了研究电场作用下NMK混凝土的微观结构变化以及整个腐蚀阶段声发射（AE）信号的演变，实验监测了全浸条件下钢筋混凝土加速腐蚀诱发开裂过程中的声发射信号。总结了不同阶段声发射信号的特征，并分析了水化产物的变化。结果表明，NMK富含Si、Al等具有火山活性的元素，促进水化产物的形成。这改善了混凝土的微观结构，有效地阻碍了氯离子在基体内的迁移，从而减缓了钢筋的腐蚀速度。通电48 h后，N5组的腐蚀速率比N0组降低了59.80%。NMK用量对水合硅酸钙凝胶（C-S-H）、氢氧化钙晶体（CH）和弗里德尔盐的形态、数量和分布有显著影响。N5组C-S-H/AFt相对含量较N0组提高70.16%。随着水泥水化的进行，NMK促进了大孔隙向小孔隙的转化。N5组总空隙体积较N0组减少21.97%。NMK可以延缓混凝土裂缝的形成，降低总能量释放率，有效抑制剪切裂缝的发展，促进拉伸裂缝的稳定扩展。

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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.