The stability of the passivation film on reinforcing steel is significantly influenced by the internal chemical environment of concrete under industrial sulfur dioxide (SO) corrosion. This study aimed to investigate the electrochemical state of the reinforcing steel and the internal chemical environment (corrosion products, phase composition, and pore structure) of concrete by conducting indoor simulations of reinforced concrete specimens exposed to industrial SO environment. The results indicated a consistent trend in open circuit potential (OCP) and corrosion current density () of steel rebar in different types of concrete. A sudden reduction in OCP is accompanied by a significant increase in when the rebars reach an active state. At this time, the ratio of sulphation depth to protective layer thickness ranges from 0.47 to 0.63. The main sulphation products were gypsum and ettringite, with their content decreasing as the cover layer depth, water-to-binder ratio, and fly ash content increased. Due to crystallization pressure and expansion, the impact of SO corrosion on the capillary pores of concrete was the most significant, followed by its effect on larger pores. After 96 days of corrosion, there was an increase of 191.7 % and 116.2 % in the quantity of pore sizes, respectively. Furthermore, the porosity growth rate in concrete with the incorporation of fly ash is lower than that of Portland concrete. This suggests that the rational use of fly ash to partially replace Portland cement is beneficial for enhancing the resistance of concrete to SO corrosion.

中文翻译：

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工业 SO2 引起的腐蚀：腐蚀开始的研究

工业二氧化硫（SO）腐蚀下混凝土内部化学环境对钢筋钝化膜的稳定性影响显着。本研究旨在通过对暴露于工业 SO 环境的钢筋混凝土试件进行室内模拟，研究钢筋的电化学状态和混凝土的内部化学环境（腐蚀产物、相组成和孔隙结构）。结果表明，不同类型混凝土中钢筋的开路电位（OCP）和腐蚀电流密度（）具有一致的趋势。 OCP 的突然降低伴随着钢筋达到活跃状态的时间显着增加。此时硫酸盐化深度与保护层厚度之比范围为0.47～0.63。硫酸盐化产物主要为石膏和钙矾石，其含量随着覆盖层深度、水胶比、粉煤灰含量的增加而降低。由于结晶压力和膨胀作用，SO腐蚀对混凝土毛细孔的影响最显着，其次是对较大孔隙的影响。腐蚀96天后，孔径数量分别增加了191.7%和116.2%。此外，掺入粉煤灰的混凝土的孔隙率增长率低于波特兰混凝土。这表明合理使用粉煤灰部分替代硅酸盐水泥有利于增强混凝土的抗SO2腐蚀能力。