迁移性阻锈剂对氯盐污染混凝土耐久性的影响——电化学性能与渗透浓度前锋线(英文)

EFFECT OF MIGRATORY CORROSION INHIBITORS ON THE DURABILITY OF CHLORIDE-CONTAMINATED REREINFORCED CONCRETE——ELECTROCHEMICAL PERFORMANCE AND PENETRATION CONCENTRATION

钢筋锈蚀是混凝土结构提前破坏的主要原因,为提高氯盐环境下混凝土结构耐久性并延长其使用寿命,人们采取了包括掺入外加剂、应用高性能混凝土和环氧涂敷钢筋在内的很多方法,这些方法中迁移性阻锈剂(migratory of corrosion inhibitors,MCIs)在作为混凝土添加剂、表面涂敷和结构修补的应用中表现出很大的灵活性。研究了表面涂敷氨基醇和羧酸胺基迁移性阻锈剂(400g/m2)对掺加胶材总量0.5%氯化钠的C30混凝土中钢筋锈蚀的抑制效果及其在混凝土中的迁移性能,监测了涂敷MCIs前后混凝土试件中钢筋的电化学阻抗谱、开路电位、线性极化电阻和腐蚀电流。结果表明:涂敷迁移性阻锈剂60d后钢筋混凝土试件平均腐蚀电流从涂敷前3.77μA/cm2降低为0.104μA/cm2,尤其是涂敷#6阻锈剂腐蚀电流最低可降低到涂敷前的1.1%;渗透浓度前锋线的分析结果表明:在保护层下30～40mm处仍能检测到较高含量的有机氮,表明迁移性阻锈剂确实通过毛细孔和微细裂缝渗透进入了混凝土内部和钢筋表面,即使在氯盐条件下钢筋产生了锈蚀,在硬化混凝土表面涂敷迁移性阻锈剂也能有效抑制钢筋锈蚀发展或使其修复。

Corrosion of the steel bars in concrete is the major cause of premature deterioration of reinforced concrete structures. To improve the durability and extend the service life of concrete structures under chloride condition, various methods （such as adding admixture, using high performance concrete and epoxy coated steel bar） have been used. In the existing techniques available, the migration of corrosion inhibitors （MCIs） used as admixtures shows a versatility in the surface treatments and in rehabilitation. The inhibiting effectiveness and the migratory performance of amino alcohol （AMA） and amine carboxylate for the MCIs in chloride contaminated concrete were investigated. The harden reinforced concrete specimens（C30） contaminated with 0.5% NaCl by mass of the cementitious materials in the mixing process were experienced by a adequate curing and were subjected to two-month exposure tests after painting with 400 g/m^2 of the MCIs. The corrosion behavior of the steel bar in specimens was monitored using electrochemical impedance spectroscopy （EIS）, open circuit potential, linear polarization resistance （LPR） and corrosion currents. The results show that the steel bars in concrete samples after surface painting the MCIs for 60 d give a lower corrosion current of 0.104μA/cm^2, compared to the untreated sample（3.77μA/cm^2）. The minimum corrosion current of the sample coated with #6 inhibitor could be reduced to 1.1% of the untreated sample. The nitrogen concentration depth profiles for concrete samples treated with the MCIs were analyzed. The higher organic nitrogen content in the depth of 30-40 mm indicates that the inhibitors assuredly migrate through the concrete capillary and micro-crack to the steel bars in cover concrete. The results show that the MCIs are effective in the suppression of the corrosion development or the rehabilitation of the corrosive steel bar when they are applied on the surface of the hardened concrete even though the initiation of corrosion in the presence of chloride.