Corrosion inhibitors for the rehabilitation of reinforced concrete
Corrosion inhibitors for the rehabilitation of reinforced concrete
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发表时间：
2000-03
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通讯作者：
D. Anstice
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作者：
D. Anstice
研究了四种缓蚀剂亚硝酸钠、一氟磷酸钠、乙醇胺和醇胺混合物在不同pH值和氯离子浓度的模型电解液中浸泡42天，以模拟碳化和/或氯离子污染混凝土中的气孔溶液相。对单氟磷酸钠和烷醇胺类缓蚀剂进行了现场试验，研究了它们对混凝土的渗透深度。研究了不同碳化气氛对水化水泥浆体孔溶液化学组成和微观结构的影响。通过监测实验室样品孔溶液中的离子迁移，研究了碳化水泥浆体的物理再矿化和以亚硝酸钙为基础的氯离子污染水泥浆体腐蚀修复体系。主要研究结果如下：1、在不同pH值和氯离子浓度的饱和空气水溶液中，亚硝酸钠、一氟磷酸钠、乙醇胺和醇胺混合物均表现出对钢的钝化阳极缓蚀剂的作用。2、单氟磷酸钠按供应商推荐使用时，未能显著渗透到部分碳化现场混凝土中。磷酸盐和氟化物在单氟磷酸钠处理的部分碳化现场混凝土中渗透5 mm。3、发现烷醇胺类缓蚀剂中的乙醇胺组分已渗透到部分碳化部位的混凝土中。4.碳化水化水泥浆体在亚硝酸钠饱和溶液上碳化，导致碳化浆体孔隙溶液中亚硝酸盐浓度显著升高。研究了氯化钠、硝酸铵、硝酸镁和重铬酸钠的饱和溶液，并确定它们是控制碳化环境相对湿度的替代品。5.在饱和条件下，由于羟基离子的扩散，硬化碳化水泥浆体的物理再矿化程度有限。然而，扩散到碳化水泥浆体中的相当大一部分羟基离子被结合到水泥基质中。再矿化水泥浆体的孔溶液中羟基离子浓度保持在5 mmol/L以下。6、亚硝酸根离子在饱和未碳化水化水泥浆体的孔溶液中扩散穿透距离较大。
Four corrosion inhibitors namely sodium nitrite, sodium monofluorophosphate, ethanolamine and an alkanolamine-based mixture were studied by immersing mild steel bars for 42 days in model electrolytes of varied pH and chloride concentration which were intended to simulate the pore solution phase present within carbonated and/or chloride-contaminated concrete. Site trials were carried out on sodium monofluorophosphate and the alkanolamine-based inhibitor to study their depth of penetration into concrete. The influence of various carbonating atmospheres on the pore solution chemistry and microstructure of hydrated cement paste was investigated. Physical realkalisation of carbonated cement paste and a calcium nitrite-based corrosion rehabilitation system for chloride-contaminated cement paste were investigated by monitoring ionic transport within the pore solution phase of laboratory specimens. The main findings were as follows: 1,Sodium nitrite, sodium monofluorophosphate, ethanolamine and the alkanolamine-based mixture all behaved as passivating anodic inhibitors of steel corrosion in air-saturated aqueous solutions of varied pH and chloride concentration. 2,Sodium monofluorophosphate failed to penetrate significantly into partially carbonated site concrete when applied as recommended by the supplier. Phosphate and fluoride penetrated 5mm into partially carbonated site concrete treated with sodium monofluorophosphate. 3,The ethanolamine component of the alkanolamine-based inhibitor was found to have penetrated significant depths into partially carbonated site concrete. 4,Carbonating hydrated cement paste over saturated solutions of sodium nitrite resulted in significant concentrations of nitrite in the pore solution of the carbonated paste. Saturated solutions of sodium chloride, ammonium nitrate, magnesium nitrate and sodium dichromate were investigated and identified as alternatives for controlling the relative humidity of the carbonating environment. 5,Hardened carbonated cement paste can by physically realkalised to a limited extent due to the diffusion of hydroxyl ions under saturated conditions. A substantial proportion of the hydroxyl ions that diffused into the carbonated cement paste however, became bound into the cement matrix. Hydroxyl ion concentrations remained below 5mmol/l within the pore solution of the realkalised cement paste. 6, Nitrite ions penetrated significant distances by diffusion within the pore solution of saturated uncarbonated hydrated cement paste.