Electrochemical chloride extraction (ECE) based on the high performance conductive cement-based composite anode

Abstract

The chloride ions, imbibition in the reinforcement concrete, are detrimental to the durability of the material. In this paper, a low shrinkage and high ductile conductive cement-based mortar was developed as a novel external anode for electrochemical chloride extraction (ECE). The electricity resistivity, fracture energy and drying shrinkage of mortar with different length, volume fraction of carbon fiber were investigated to optimize mix proportion of conductive cement base mortar (CCM). Subsequently, the proposed CCM with good performance was then utilized as the anode to remove the chloride ions electrochemically from three types of reinforced concrete. The chloride ions distribution in concrete and CCM anode were obtained to evaluate the electrochemical chloride extraction (ECE) efficiency. Additionally, the microstructures, elements distribution and calcium hydroxide content of CCM anode and ITZ were achieved for the further mechanism investigation. Experimental results indicated that the ECE efficiency for CCM anode was as high as that of traditional stainless mesh anode. The CCM anode with 0.8% volume fraction of carbon fiber exhibits excellent ductile and conductivity performance. Furthermore, CCM anode thickness influences significantly on the chloride removal efficiency and residual chloride proportion in concrete and CCM anode. And 10 mm thickness of CCM anode was a suitable value to ECE treatment of reinforced concrete. The microstructure and calcium hydroxide content in CCM anode showed no degradation after 35 days of ECE treatment, which indicated that the CCM anode have an excellent cracking resistance capacity and could be re-used.