Study On The Performance Of Zn-Al Composite Sacrificial Anode And Application Of Its In The Reinforced Concrete Structure At The Splash Zone

In recent years, along with the corrosion situation of concrete structures in marine environment becoming increasingly serious, the sacrificial anode material and sacrificial anode cathodic protection technology has also been growing, but the traditional sacrificial anode materials stretched to protect the splash zone that crossion is most serious. Composite anode with high current efficiency, high activity, high electrochemical capacity, full of possibilities for the protection of the concrete structure of splash zone, so it is important to develop a new type of composite sacrificial anode to protect concrete structure of splash zone in marine environment.In this paper, Composite sacrificial anodes that conform to national stand are prepared, the electrochemical performance of composite anode is compared with aluminum anode and zinc anode with electrochemical test methods. Results show that the current efficiency of composite anode is is superior to aluminum anode and the actual electrochemical capacity is better than that of zinc anode. Polarization curve and EIS of these anodes in 3.5% Na Cl solution and 3.5% Na Cl-saturated Ca(OH)2 solution are tested to study the dissolve law, dissolve rate and applicability by chemical workstation. Results show that the activity of composite anode in solution between that of zinc anode and aluminum anode. The dissolution rate of the composite anode can be divided into acceleration, transition, deceleration three stages in 3.5% Na Cl solution, and that can be divided into deceleration, transition, deceleration in 3.5% Na Cl-saturated Ca(OH) 2.Finally, the potential of steel protected by zinc anode, aluminum anode and composite anode, which is placed in 3.5% Na Cl solution, 3.5%Na Cl-saturated Ca(OH)2 and concrete briquette, which water-cement ratio is 0.3 and 0.4, and which the thickness of concrete cover is 10 mm and 15 mm,under the condition of dry-wet circulation, is tested to study polarization effect of these anodes. Results show that all steels unprotected rust, and the potential of all steels protected stay between-1.1V and-0.9V(vs SCE) after 12 hours, in 3.5% Na Cl solution. After steels, which had rusted, are protected by composite anode, the potential of steels rapidly drop to around-0.9V(vs SCE), and large areas of rust off the surface of steel. The potential of steel stay at-1.1V(vs SCE) in 3.5%Na Cl-saturated Ca(OH)2 in the beginning of the experiment, and local areas of steels unprotected rust, indicating that composite anode can provide relatively and more stable protection to steel. The potential of steel stay between-1V and-0.9V(vs SCE) in concrete briquette under the condition of dry-wet circulation,in conformity with the experiment result of EIS and polarization test, and water-ratio and the thickness of concrete cover do not appear to influence the potential of steel in concrete.