Title: Effect of Concrete Settlement Cracks on Corrosion Initiation
Author(s): M. O’Reilly, J. Lafikes, O. Farshadfar, P. Vosough Grayli, O. Al-Qassag, and D. Darwin
Publication: Materials Journal
Appears on pages(s): 117-124
Keywords: chlorides; corrosion; crack width; reinforcing steel; settlement cracking
The effects of settlement cracking in concrete on corrosion initiation and rate of reinforcing steel in the presence of chlorides are evaluated using uncracked southern exposure (SE) specimens, cracked beam (CB) specimens with 0.012 in. (0.3 mm) artificial cracks directly above reinforcing steel, and settlement cracking (SC) specimens in which cracks with widths ranging from 0.001 to 0.004 in. (0.025 to 0.10 mm) form in plastic concrete over reinforcing bars. The earliest corrosion initiation was observed in the CB specimens, followed, in turn, by the SC and SE specimens. Although narrow, settlement cracks can lead to early initiation of corrosion—on average of less than half the time than for uncracked concrete. Relative to uncracked concrete, specimens with settlement cracks exhibited a 30% increase in corrosion rate while specimens with the artificial 0.012 in. (0.3 mm) crack exhibited an over 200% increase in corrosion rate.