Results of a 2-year field study performed in Switzerland to evaluate t
he process and to obtain information on the efficiency of electrochemi
cal chloride removal as a restoration technique for chloride contamina
ted concrete are presented. It is shown that about 50% of the initial
chloride content is removed within 8 weeks (ca 5 x 10(6) cm-2). In the
treated zones of the structure the half-cell potentials became more p
ositive by about 80-100 mV. A comparison with the theoretical efficien
cy for chloride removal, calculated from the transference number of ch
loride ions, show that mainly the free chlorides in the pore solution
of the concrete are removed. Due to the slow chemical equilibrium betw
een bound and free chlorides, a second treatment after several months
also removes originally bound chlorides. For severe and inhomogeneous
chloride contamination local zones with active rebars and high chlorid
e content may remain after the treatment.