Conductive Cement Pastes With Carbon Fibers As Anodes In The Electrochemical Chloride Extraction

The use of cement-based multifunctional materials as anodes in the protection against corrosion and in the repair of reinforced concrete structures are actually of great interest among scientists and engineers due to the benefits that present the methods of nondestructive rehabilitation. By nature, cement based materials have acceptable mechanical properties, however their electrical properties are deficient; the addition of conductive carbon materials such as graphite powder, coke powder or carbon fibers makes them multifunctional materials of suitable mechanical and electrical properties. This paper presents the study of the performance of a conductive cement paste (CCP) with the addition of crushed coke and carbon fiber (CF) as anode in the electrochemical chloride extraction in contaminated concrete with 2.31% chloride according to the weight of cement, studying the PCC as an alternative use of multifunctional materials in electrochemical techniques. A comparative is made in the performance of 3 anodes: stainless steel mesh, CCP without addition of carbon fiber and CCP with addition of 0.90% of CF in volume fraction, with the use of an alkaline electrolyte of lithium borate and current density of 4.0 A/m(2) on the steel surface. In addition, it was monitored subsequent corrosion potentials to Electrochemical Chloride Extraction (ECE) and pH variation in electrolyte and concrete mass. The anode of CCP with addition of CF presented chloride contents of 0.22% after 21 days of ECE, with free extractions of chlorides with up to 90.4% CCP with CF, while the technique with stainless steel mesh presented a 77.6%. The results provide an important advance in the improvement of the performance of anodes of multifunctional materials in electrochemical techniques used in rehabilitation of reinforced concrete structures contaminated with chlorides.