钢筋混凝土在线腐蚀监测中护环电极智能约束研究

SMART CONFINEMENT OF GUARD RING ELECTRODE TECHNIQUE FOR ONLINE MONITORING OF CORROSION OF REINFORCED CONCRETE

基于护环电极（GRE）原理，研究了提高钢筋混凝土在线腐蚀速率测量精度的方法；通过GRE电极将极化电流约束在辅助电极CE投影面区域内的钢筋网架内确定钢筋的被极化面积；同时，采用智能GRE电流约束值修正程序，使钢筋腐蚀速率测量值与均匀极化技术测量值保持一致性．结果表明，GRE约束系数入与混凝土自生电阻率及钢筋腐蚀状态有一定的函数关系，当GRE电流对CE极化电流进行完全约束时即λ=1，钝化态钢筋腐蚀速率将比实际值偏小几倍．要准确测量钢筋锈蚀速率，钢筋自腐蚀电位Ecorr越负，混凝土电阻尺。越小，则约束系数入也必须减小，基于此文中提出了一种基于Ecorr和Rc的智能约束系数计算程序，并研制了便携式在线钢筋锈蚀检测仪．现场试验证明：对于活化态钢筋，λ=0．2-0．6，而对于钝化态钢筋，λ=0．5-0．8时腐蚀速率测量结果较为准确．

Based on the principle of the guard ring electrode （GRE） , a guard ring is applied to confine the spread of CE polarization current within a constant area. The quasi-proportional relationship between the confinement efficiency A and the electrical resistivity（pc ） of the concrete and the half-cell potential EHC of the concrete has been found after comparing the results measured by Guard Ring Method（GRM） and Uniform Polarization Method （ UPM ）. Full confinement （ λ = 1 ） for the CE polarization current will lead to a underestimation of concrete corrosion rates in passive state. Meanwhile, in order to obtain the accurate corrosion rate, a A value varied with the self corrosion potential Ecorr of the rebar and the concrete resistance Rc by the help of smart arithmetic is more suitable than a constant value generally applied in some commercial corrosion meter. We found that the A value should decrease as Rc decreases and Ecorr going negative. In fact, GRM can give accurate corrosion rate in active rebar state w only when the A ranged in 0. 2 - 0. 6, and in passive state only when the A within the range 0. 5 - 0. 8.