Statistical Distributions for the Corrosion Rates of Conventional and Prestressing Steel Reinforcement Embedded in Chloride Contaminated Mortar

Many concrete structures are built using plain mild (PM) and cold-twisted deformed (CTD) steel rebars. Also, quenched and self-tempered (QST) and prestressing (PS) steels are extensively used in today’s construction. For estimating the corrosion propagation period (t_p) of concrete structures, the current practice is to assume that the corrosion rate (i_corr) of different steels are equal to that of PM steel—leading to erroneous estimation of t_p. This paper provides i_corr data from a 33-month experiment on PM, CTD, QST, and PS steels embedded in chloride contaminated mortar. Linear polarization resistance test was adopted for i_corr measurement. A total of 100 specimens were tested. It was found that the CTD and QST steels exhibit higher i_corr than the PM and PS steels. The paper also provides statistical distributions for i_corr of these four steels. For PM, CTD, QST, and PS steel embedded in chloride contaminated mortar, and exposed to wet-dry conditions, these are found to be ∼Weibull (2.5, 20.7, 0) μA/cm², ∼Lognormal (0.45, 3.2, 0) μA/cm², ∼Gamma (6.8, 3.5, 0) μA/cm², and ∼Weibull 3P (1.3, 6.5, −0.02) μA/cm², respectively. Similar distributions for dry condition are also presented. These statistical tools would help engineers in estimating residual service life and scheduling repair activities.