Preliminary Study of the Influence of Supplementary Cementitious Materials on the Application of Electro Remediation Processes

Abstract

Supplementary cementitious materials (SCMs), based on pozzolanic materials, improve durability against corrosion and mechanical properties of concrete structures by decreasing their permeability. Even though the influence of SCMs on the chloride combination with the cement phases has been widely studied, its effects on electrokinetic remediation processes such as electrochemical chloride extraction (ECE) have not been clarified. For this reason, the influences of two SCMs, fly ash (FA) and blast-furnace slag, on the extraction of chloride through the concrete net pore have been studied in this paper to determine the viability of the application of electrochemical chloride treatments in these structural materials. Alternative electrochemical indicators to the ones included in the standards are also proposed to better determine the final point of the treatment. A cement replacement of 8% on both SCM (FA and slag) has been tested, and in addition to charge density, chloride content, and corrosion measurement at the end of the treatment (included in the standards), different electrical and electrochemical indicators such as electrical resistivity, EIS, or depolarized potentials are used to monitor the ECE. The influence of the treatment on disconnected steel has been also studied. In the case of slag mortar, no steel passivation was reached, while in the case of FA, the passivation of the steels connected to treatment was reached in the same way as in plain CEM I specimens. A degree of protection is also detected in the nonconnected steel, which means that substitution of 8% in FA does not affect treatment efficiency and can also partially protect the metallic elements embedded in the same electrolyte but not connected to the treatment.