混凝土构件中钢筋锈蚀的电加速技术对比试验研究  

Experimental comparison of galvanostatic methods for accelerated corrosion of steel bars in RC members

作　　者：王晓刚 杜相波[1] 闫军印[1] 方召欣[1] 

机构地区：[1]烟台大学土木工程学院,山东烟台264005

出　　处：《建筑结构学报》2015年第1期104-110,共7页Journal of Building Structures

基　　金：国家自然科学基金项目(51108400);山东省自然科学基金青年基金项目(ZR2013EEQ018)

摘　　要：采用试验方法对实验室中常用的获取锈蚀钢筋混凝土构件的电加速锈蚀技术进行对比研究。共设计了8块混凝土板试件,考虑钢筋直径和锈蚀电流密度不同,分别采用全浸入法、半浸入法和干湿交替法进行电加速锈蚀,通过激光扫描建模对锈蚀钢筋表面特征进行统计分析,对比不同方法下的锈蚀不均匀性和锈胀裂缝发展。结果发现,半浸入法和小电流干湿交替法中钢筋实际锈蚀程度明显小于法拉第定律的预测值。钢筋区段最大截面锈蚀率与平均锈蚀率的比值可用来量化锈蚀不均匀性,该比值服从广义极值分布,并受钢筋直径和截断长度的影响。全浸入法得到锈蚀钢筋的不均匀性较差,胀裂开展速率最低,不宜采用。半浸入法得到锈蚀钢筋不均匀性好,但胀裂开展速率较低,在针对锈蚀钢筋本身的研究中可采用。干湿交替法在两方面表现均较好,建议采用,但外加电流密度不宜大于50μA/cm2。Comparison was made experimentally among the varied galvanostatic methods that are commonly used in laboratory to obtain corroded reinforced concrete( RC) specimens. Eight concrete slabs were prepared for accelerated corrosion using full-immersion,half-immersion and wet-dry cycling methods,with different diameters of steel bars and impressed current densities. Modeling of the corroded bars was realized through 3D laser scanning to facilitate the statistical analysis on surface characteristics of the bars,and uneven corrosion distribution and expansive cracking were investigated comparatively. Shown by the results,half-immersion and low current wet-dry cycling methods both result in lower corrosion degree compared with the expectation of Faraday's law. A ratio R can be used to quantitate uneven corrosion of a rebar section,which is defined as the maximum cross-sectional area loss ratio divided by the average weight loss ratio. R value obeys general extreme value distribution,affected by sample diameter and length. Fullimmersion method is not an ideal method,considering the fact that it generates lower uneven corrosion and lightest crack expansion. Half-immersion method can be used in the research focusing merely on corroded bars,since it leads to higher uneven corrosion but less severe cracking. Wet-dry cycling seems to be the best,whereas the impressed current density is recommended to be below 50 μA / cm2.

关 键 词：钢筋混凝土构件 钢筋 电加速锈蚀 干湿交替法 电流 不均匀性 锈胀裂缝 

分 类 号：TU375[建筑科学—结构工程]