矿物掺合料对钢筋氯盐腐蚀行为的影响及其作用机理

用水泥提取液模拟混凝土孔隙液,用自腐蚀电位、动电位极化和电化学阻抗技术,研究单掺粉煤灰或矿粉、复掺粉煤灰和矿粉对混凝土中钢筋氯盐腐蚀行为的影响.结果表明,粉煤灰和矿粉均能有效降低钢筋受氯离子腐蚀的风险,减小腐蚀速率,并能不同程度地提高钢筋腐蚀的临界氯离子浓度.抑制氯离子腐蚀能力由强到弱依次为:矿粉>矿粉+粉煤灰>粉煤灰>水泥.且随氯离子浓度的增大,矿粉和粉煤灰的阻锈效率会有不同程度的下降.用矿粉和粉煤灰按适当比例复掺的方法来对抗氯离子腐蚀不仅经济,而且有不错的阻锈效果.

Mechanism and Effect of Mineral Admixtures on Corrosion Behavior of Reinforcing Rebar in Cement Extracts Contaminated with Chlorides

By means of free corrosion potential measurement,potentiodynamic and electrochemical impedance spectroscopy etc,the effect of fly ash and slag on corrosion behavior of reinforcing rebar was investigated in solution of cement extract with contaminant of chlorides,which was adopted to simulate the known concrete pore solution in reinforcements.The results show that fly ash and slag can effectively reduce the risk of chloride induced corrosion and the corrosion rate of reinforcing steel rebar.Besides,the threshold value of chloride for corrosion is increased to some extence.The inhibition ability to chloride induced corrosion is in the order of: slag > slag + fly ash > fly ash > cement.In addition,the corrosion inhibition efficiency of slag and fly ash decreases to some extent with the increase of the chloride concentration.The admixture of fly ash and slag at a appropriate proportion is excellent corrosion inhibitor for chloride induced corrosion to steel rebar in terms of cost and effectiveness.