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At least 325 records · Page 18

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DOE OSTI2021

Corrosion of rebar in concrete. Part II: Literature survey and statistical analysis of existing data on chloride threshold

The literature is reviewed with respect to defining, measuring, and interpreting the chloride threshold (CT). CT was defined with a strong fundamental basis in the Point Defect Model. which also dictates the nature of the statistical analysis of surveyed CT values. A database of CT for various primary and secondary independent variables has been established. Statistical analyses reveal that CT is lognormally distributed, in accordance with the PDM, with most probable values being 0.85, 0.69, and 1.19 for %total Cl/cem, %free Cl/cem, and [Cl - ]/[OH - ], respectively. The breakdown and corrosion potentials follow normal distributions with means of 0.056 and -0.322 V SCE , respectively.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Corrosion of rebar in concrete. Part IV. On the theoretical basis of the chloride threshold

A theory is developed for calculating the chloride threshold (CT) from the Point Defect Model (PDM). CT is defined as the ratio [Cl - ]/[OH - ] at which the passivity breakdown voltage (E b ) equals the corrosion potential, ECP. CT is sensitive to the T, ECP, pH, and E b , because all four appear in the exponent X in CT = 10 X . Small uncertainties in these parameters translate into a large uncertainty in CT, emphasizing the need for accurate T, ECP, pH, and E b data. We demonstrate the theory by successfully calculating CT using data for selected systems.

36 MATERIALS SCIENCE↗

DOE OSTI2020