Electro active repair of concrete demonstration of applicability

Abstract

Conventional concrete patch repairs have poor durability: 50% fail within ten years. A major cause is insufficient removal of contaminated concrete and insufficient steel cleaning. Chlorides left behind reactivate the corrosion process. The effects of various cleaning methods of reinforcing steel suffering chloride induced corrosion were compared in a demonstrator in form of a concrete slab. Rebars were cleaned by A) applying 5 A/m2 direct current for 24 hours in tap water saturated with calcium hydroxide according to a patented method, “Electro Active Repair (EAR)”, B) blasting using rubber particles (sponge jet), C) steel wire brushing, or D) not cleaned. The main conclusion is that applying electrical current for a short period (24 h) effectively removed chloride from corrosion products and pits, and increased the pH of the solution in corrosion pits. Consequently, adding cleaning of the rebars by EAR to the conventional repair process is expected to improve the durability of conventional concrete repair.