Experimental Program
To consider the asymmetry of underground structure restoration,the device of the EDM can be summarized as follows.The embedded rebars of the concrete structure and the titanium plateare connected to the negative terminaland positive terminalof the power supply,respectively,as displayed in Figure 1.The cracked concrete specimen is put between the water and electrolyte,while titanium plates are immersed in alkaline electrolyte.There is a continuous electrochemical deposition in the concrete member or structure when an appropriate direct current(DC)is maintained in the system.Therefore,the cracks and pores in the concrete members and structures can be healed or filled gradually by the deposition products.
Figure 1 Experimental device
The main electrochemical reactions during the electrodeposition are as follows:
Cathodic reaction:
Athodic reaction:
where Y 2+is the ion in the solution,such as the Mg2+and Ca2+.In the experiment,the influence of electrolytes,electrodes,modes of cathode connection are considered.Meanwhile,the surface coverage and the microstructures are adopted to assess the repairing effects.