The Effect of Electrochemical Chloride Extraction Treatment on the Microstructure and Mechanical Properties of Cementitiuos Materials

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Title: The Effect of Electrochemical Chloride Extraction Treatment on the Microstructure and Mechanical Properties of Cementitiuos Materials

Author(s): T. D. Marcotte, N. M. Ihekwaba, C. M. Hansson and B. B. Hope

Publication: Special Publication

Volume: 171

Issue:

Appears on pages(s): 507-530

Keywords: Bond strength; chlorides; compressive strength; density; energy; microstructure; porosity.

Date: 8/1/1997

Abstract:
Electrochemical chloride extraction is a rehabilitation process aimed at reducing the chloride levels of contaminated reinforced concrete structures to below the critical values for corrosion of the reinforcing steel (rebar). While this has been demonstrated to be feasible, the effects of the treatment on the microstructure and the mechanical properties of the concrete have not yet been adequately documented. This research attempts to characterize the changes in concrete and mortar, particularly at their interface with the rebar, due to an extraction treatment. To this end, concrete specimens with 3.0% Cl by mass of cement, and mortar specimens with 2.0% Cl by mass of the cement were cast, cured and, after various exposures, subjected to electrochemical chloride extraction treatments typical of those applied commercially. The mortar specimens were examined metallographically while concrete specimens were subjected to mechanical durability studies. It is clear from this study that the structure and mechanical properties of the concrete immediately adjacent to the reinforcing steel are severely degraded by the electrochemical extraction treatment. It remains to be seen if the damage is permanent or if there is a subsequent redistribution of ions which could ameliorate the structure and, hence, the properties.