Nr. Buenfeld et Jp. Broomfield, Influence of electrochemical chloride extraction on the bond between steeland concrete, MAG CONCR R, 52(2), 2000, pp. 79-91
Laboratory tests were undertaken to assess the effect of electrochemical ch
loride extraction (ECE) on the bond strength of plain reinforcing steel in
concrete. Specimens were cured/stored for 3 months prior to ECE and were th
en treated at a current density of between 0.02 and 0.75A/m(2) of reinforce
ment area for periods of up to 32 weeks. Chloride-free specimens showed a s
mall gradual increase in bond strength after ECE. Prior to ECE, specimens c
ontaining chloride (1.5% by weight of cement) had higher bond strength than
chloride-free specimens, due to corrosion. This enhanced bond strength was
largely eliminated by 2 weeks of ECE, due to dissolution of corrosion prod
ucts, although these specimens also then showed a slight increase in bond s
trength after further treatment. Tests carried out 10 min, 24 h and 28 days
after ECE suggest that bond strength reduces during ECE. Variations in bon
d strength are considered with regard to the processes occurring during ECE
, and the practical implications of these findings are discussed.