为了揭示Cl?傆b、SO42?傆b作用下混凝土中钢筋腐蚀机理的差异, 并为氯盐和硫酸盐侵蚀下混凝土的抗腐蚀调控提供理论基础, 研究了Cl?傆b、SO42?傆b侵蚀下混凝土孔溶液中钢筋的电化学行为差异, 并利用基于第一性原理的密度泛函理论研究了腐蚀性物质(Cl?傆b、SO42?傆b)和致钝物质(CaOH+、OH?傆b)在Fe(100)表面的竞争吸附。结果表明: 相较于含Cl?傆b的混凝土孔溶液, 钢筋在含SO42?傆b的混凝土孔溶液中的腐蚀电位和极化电阻均更低, 更易发生腐蚀; SO42?傆b对OH?傆b与铁表面反应的抑制作用略强于Cl?傆b; SO42?傆b既可促使CaOH+中Ca-OH键伸长, 又可阻碍CaOH+中OH基团与表面Fe原子间的作用, 其对CaOH+与铁表面反应的抑制作用明显强于Cl?傆b。

To reveal the difference of corrosion mechanism of steel bars in concrete under Cl?傆b and SO42?傆b action, and provide the theoretical basis for the control of concrete corrosion resistance under chloride and sulphate attack, the electrochemical behavior of reinforcement subjected to Cl?傆b and SO42?傆b in concrete pore solutions was investigated, and the competitive adsorptions of corrosive ions (Cl?傆b, SO42?傆b) and passive ions (CaOH+, OH?傆b) on the Fe (100) surface were analyzed by the density functional theory based on the first-principles. The results show that the corrosion potential and polarization resistance of steel reinforcement in concrete pore solution with SO42?傆b both are lower than those in concrete pore solution with Cl?傆b, indicating that the steel reinforcement corrosion occurs more easily in concrete pore solution with SO42?傆b. The inhibition effect of SO42?傆b on the reaction of OH?傆b and iron surface is slightly stronger than that of Cl?傆b. Moreover, SO42?傆b can promote the elongation of Ca-OH bond, and block the interaction of the OH group in CaOH+ and surface Fe atom, showing that the inhibition effect of SO42?傆b on the reaction of CaOH+ and iron is stronger than that of Cl?傆b. The results reveal the corrosion mechanism of steel reinforcement under the attack of Cl?傆b and SO42?傆b in concrete.