10123 Projecting Time-to-Corrosion for Black and Corrosion Resistant Reinforcement in Concrete Exposed to Chlorides

Available for download

Product Number: 51300-10123-SG

ISBN: 10123 2010 CP

Author: William H. Hartt

Publication Date: 2010

Member Price: $0.00

Non Member Price: $20.00

Price: $20.00

Qty:

A protocol is described whereby time-to-corrosion, T_i, of reinforcing steel in concrete exposed to chlorides was calculated as a distributed, rather than discrete, parameter. The method consists of inputting 1) an average value for surface [Cl^-] and the effective diffusion coefficient, 2) the mean and standard deviation of concrete cover over the reinforcement, and 3) a distribution function for the critical Cl^- threshold concentration to initiate corrosion, C_T, based upon values previously reported. The calculation result is a cumulative distribution function (CDF) plot of T_i. Example analyses were performed based upon a range of design and material property values of the above parameters for both past and representative, present day bridge decks and marine bridge substructures.

Results for corrosion resistant reinforcement are compared with those for black bar. It is proposed that reinforced concrete durability should be characterized not simply in terms of the time at which corrosion initiates for a small percentage of the reinforcement, as is normally done, but also by the rate at which active corrosion subsequently begins for the remaining, uncorroded reinforcement. Implications of such an approach are discussed.

Keywords: Reinforced concrete, corrosion, critical chloride threshold concentration, time-to-corrosion, bridge decks, marine bridge substructures, corrosion resistant reinforcement