氯盐环境下矿渣对混凝土中钢筋腐蚀过程的影响

Influence of slag on corrosion of steel bar in concrete under chloride attack

针对氯盐环境下钢筋混凝土的腐蚀问题,以不同矿渣掺量的水泥净浆层代替混凝土保护层,设计制作了系列钢筋混凝土试件,开展了氯盐溶液中各试件腐蚀过程的Tafel和EIS测试,分析了矿渣掺量对各试件中腐蚀电位、腐蚀电流密度、保护层电阻、钢筋表面电荷转移电阻等电化学参数的影响。结果表明,相比于未掺矿渣试件,掺矿渣试件在腐蚀初期的腐蚀电流密度较大,但随着腐蚀的进行,其钢筋表面电荷转移电阻的降低速率和腐蚀电流密度增大速率明显较小,这说明复合矿渣保护层削弱了早期的护筋能力,但能有效提高保护层对钢筋的整体抗腐蚀性能。

According to the corrosion process of reinforced concrete under chloride environment,a series of slag-cement paste-steel specimens with different slag contents have been designed to replace reinforced concrete.Then,they were measured by both Tafel and electrochemical impedance spectroscopy(EIS)under chloride corrosion solution.The effects of slag on electrochemical parameters such as corrosion potential,corrosion current density,protective layer resistance and charge transfer resistance of steel were analyzed.Results show that,compared with specimens with no slag,the corrosion current densities of slag specimens are larger at the initial corrosion stage.However,with the progress of corrosion,the reducing rate of charge transfer resistance and the increasing rate of corrosion current density are significantly smaller,which indicates that the protection layer of slag-cement weakens the early capacity in protecting steel meanwhile improves the corrosion resistance of concrete.