Impact of Experimental Parameters on Degradation Mechanism and Service Life Prediction of CFRP Anode during Simulated ICCP Process

In actual building structure, it usually takes tens of years for the degradation to be significantly observed during impressed current cathodic protection (ICCP) process. Thus, simulated ICCP with aqueous electrolyte (instead of concrete) was used as an accelerated method to study degradation mechanism and make service life prediction. In this work, the impact of parameters including current (density) and NaCl electrolyte concentration on the degradation mechanism and service life prediction was evaluated for a simulated ICCP system with CFRP as anode. Experiments were performed with different levels of applied current (4, 10, and 20 mA) as well as with different NaCl electrolyte concentrations (3, 10, and 20% by mass). Test results showed that under all the designed conditions, both chlorination and oxidation reaction occurred during the simulated ICCP process, ensuring consistency of mechanism. From the aspect of service life prediction of CFRP, it was found that the system was not sensitive to the concentration of NaCl electrolyte but was much more influenced by the current (density) applied. Thus, for the simulated ICCP system, the current (density) should be carefully chosen since a tiny change in level of current may cause a large variation in service life prediction.