石灰石粉掺量对混凝土中钢筋脱钝临界氯离子含量的影响  

Effect of Limestone Powder Content on Chloride Threshold for Rebar Depassivation in Concrete

作　　者：李辰治 蒋林华[2] LI Chenzhi;JIANG Linhua(College of Civil Engineering,Tongji University,Shanghai 200092,China;College of Mechanics and Materials,Hohai University,Nanjing 210098,China)

机构地区：[1]同济大学土木工程学院,上海200092 [2]河海大学力学与材料学院,南京210098

出　　处：《材料导报》2024年第1期72-78,共7页Materials Reports

基　　金：国家自然科学基金(52078183)。

摘　　要：本工作研究了不同石灰石粉掺量(10%、20%、30%,质量分数,下同)对钢筋脱钝临界氯离子含量的影响,对混凝土试件进行干湿循环处理以加速氯离子渗透,同时采用半电池电位和电化学阻抗谱分别测定了钢筋的自腐蚀电位和腐蚀电流密度。结果表明,临界氯离子含量随着石灰石粉掺量的增加而减小,这主要是因为石灰石粉的掺入导致水泥含量降低,从而使混凝土孔隙液pH值降低。XRD分析表明石灰石粉的掺入抑制了单硫型水化硫铝酸钙(AFm)相的生成,从而降低了水化产物的氯离子结合能力。腐蚀电流密度的变化趋势服从三参数Weibull分布,其概率密度可以表征钝化膜破裂的速率,随着石灰石粉掺量的增加,钝化膜破裂速率增加。The effect of limestone powder(LP)content on the chloride threshold for rebar depassivation was investigated.Wetting-drying cycles were conducted to accelerate the chloride penetration into concrete specimens.Half-cell potential and AC impedance techniques were employed to monitor the dynamic changes of self-corrosion potential(E corr)and corrosion current density(i corr),respectively,which were used to diagnose the corrosion condition of the rebar.The results indicate that the chloride threshold decreases as the LP content increases,which is attributed to the lower pH value of concrete pore solution due to decreased cement content.XRD patterns demonstrate that incorporating LP inhibits the formation of monosulfate(AFm)phase,thereby undermining the chloride binding capacity of the hydrates.The variation of i corr with time follows a three-parameter Weibull distribution,with the probability density representing the rate of passivity breakdown,which is found to increase with increasing limestone content.

关 键 词：石灰石粉掺量 临界氯离子含量 腐蚀电位与电流密度 钢筋脱钝 WEIBULL分布 

分 类 号：TU528[建筑科学—建筑技术科学]