Purpose

High-ductility cementitious composites (HDCC) have an excellent crack controlled capacity and corrosion resistance capacity, which has a promising application in structure engineering under harsh environment. The purpose of this study is to explore the corrosion mechanism of steel bar in HDCC.

Design/methodology/approach

Intact and the pre-cracked HDCC specimens under the coupled action of different dry–wet cycles and chloride attack were designed, and intact normal concrete (NC) was also considered for comparison. Corrosion behavior of a steel bar embedded in HDCC was analyzed by an electrochemical method, a chloride permeability test and X-ray computed tomography.

Findings

Steel corrosion probability is related to the chloride permeability of the HDCC cover, and the chloride permeability resistance of HDCC is better than that of NC. Besides, crack is the key factor affecting the corrosion of steel bars, and the HDCC with narrower cracks have a lower corrosion rate. Slight pitting occurs at the crack tips. In addition, the self-healing products and corrosion products fill up the cracks in HDCC, preventing the external aggressive ions from entering and thereby decreasing the steel corrosion rate.

Originality/value

HDCC has a superior corrosion resistance than that of NC, effects of variable crack width on corrosion behavior of steel bar in HDCC under the coupled actions of different dry–wet cycles and chloride attack are investigated, which can provide the guide for the design application of HDCC material in structure engineering exposed to marine environment.

中文翻译：

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干湿循环和氯化物侵蚀耦合作用下高延性水泥基复合材料中钢筋的腐蚀行为

目的

高延性水泥基复合材料（HDCC）具有优异的裂纹控制能力和抗腐蚀能力，在恶劣环境下的结构工程中具有广阔的应用前景。本研究的目的是探讨HDCC中钢筋的腐蚀机理。

设计/方法/方法

设计了不同干湿循环和氯化物侵蚀耦合作用下的完整和预开裂 HDCC 试样，并考虑了完整的普通混凝土 (NC) 进行比较。通过电化学方法、氯化物渗透率测试和 X 射线计算机断层扫描分析了嵌入 HDCC 的钢筋的腐蚀行为。

发现

钢材腐蚀概率与HDCC覆盖层的氯化物渗透性有关，HDCC的耐氯化物渗透性优于NC。此外，裂纹是影响钢筋腐蚀的关键因素，裂纹越窄的HDCC腐蚀速率越低。裂纹尖端出现轻微点蚀。此外，自修复产物和腐蚀产物填补了HDCC的裂缝，阻止了外部侵蚀性离子的进入，从而降低了钢的腐蚀速率。

原创性/价值

HDCC具有优于NC的耐腐蚀性能，研究了不同干湿循环和氯化物侵蚀耦合作用下不同裂纹宽度对HDCC钢筋腐蚀行为的影响，可为设计应用提供指导。暴露于海洋环境的结构工程中的 HDCC 材料。