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

Abstract

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 (tp) of concrete structures, the current practice is to assume that the corrosion rate (icorr) of different steels are equal to that of PM steel—leading to erroneous estimation of tp. This paper provides icorr 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 icorr measurement. A total of 100 specimens were tested. It was found that the CTD and QST steels exhibit higher icorr than the PM and PS steels. The paper also provides statistical distributions for icorr 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.