再碱化后钢筋混凝土电化学性能

采用交流阻抗谱和极化曲线,对再碱化后钢筋混凝土进行电化学研究.再碱化试验参数是:电流密度3A.m-2,5A.m-2;再碱化天数14和28d;电解液为1mol/L的碳酸钠电解液.同批碳化试件分8组再碱化,时间间隔为1,2,3,8,9,10,13个月,然后放入室内.再碱化试验结束后,测试钢筋混凝土的交流阻抗谱、钢筋的开路电位、腐蚀电流和pH;对再碱化后试件的开路电位从-1 100mV经过一定时间正移到-300mV以上的现象进行再碱化模拟试验研究.结果表明,再碱化过程中,阴极钢筋处产生的氢气使钢筋的再钝化比较缓慢;再碱化处理之后要弛豫一段时间才可检测钢筋电化学;在本试验条件下,再碱化后钢筋混凝土电化学性能随着时间衰减;再碱化后10～13个月,电化学性能逐渐趋于稳定.

Electrochemical study on carbonated concrete after realkalisation

Electrochemical properties of carbonated concrete after realkalisation were studied with electrochemical impedance spectroscopy(EIS) and polarization curves.The parameters of realkalisation were current density,3 A·m-2 and 5 A·m-2,realkalisation time,14 d and 28 d,the concentration of sodium carbonate solution,1 mol·L-1.The group of carbonated samples was 8.The first group was realkalisated,seven other groups were realkalisated every 2,3,4,9,10,11,14 months. All samples were kept indoors.The electrochemical impedance spectroscopy,open circuit potential(OCP),corrosion current and pH were measured after the realkalisation experiment.And the realkalisation simulated experiment was done for explaining the phenomea that the OCP was increasing from-1 100 mV to-300 mV with the time after realkalisation.The test results show that the hydrogen generating at the cathode rebar during the experiment delay the re-passivation of rebar,and the electrochemical measurements werenot done until after the relaxation.Under the experiment conditions,the electrochemical properties of carbonated concrete decay after realkalization.Within 10-13 months after the realklaisation,the electrochemical properties become gradually steady.