Influence of surface crack width on bond strength of reinforced concrete

This paper reports the results of an experimental program to investigate the changes in the bond characteristics of deformed mild steel reinforcing due to chloride-induced corrosion. The principal parameters investigated are the cover depth, bar diameter, degree of corrosion, and the surface crack width. The results show a strong relationship between the average surface crack width and the average bond strength; the degree of corrosion does not demonstrate such a clear relationship. The bars with a 1 C/F (cover/diameter) show an initial increase in bond strength at the first visible crack; no similar initial increase is observed for the bars with 3 C/F. The bottom-cast bars display a higher bond strength with no corrosion, but a similar bond strength is observed for both top- and bottom-cast bars once cracking is observed.