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The Accelerated Corrosion Testing Method (ACTM) uses anodic polarization to accelerate corrosion by providing a potential gradient, driving negatively charged chloride ions through the grout to the steel. The ACTM is intended to provide a relative comparison of a grout's corrosion resistance. The time to corrosion cannot be directly related to field performance, but can be compared with grouts with known acceptable performance. The ACTM is particularly useful in determining combinations of admixtures that may adversely affect a grout's corrosion performance. Previous ACTM testing did not include correction for the ohmic resistance (or IR drop) of the grout which changes with the addition of chemical and mineral admixtures. Grouts with different omhic resistances will have different polarized potentials at the steel/grout interface. The polarization read by the potentiostat cannot be read directly at the steel/grout interface, so differences in the omhic resistance of the grout will affect the actual polarization potential. In the present study, a potentiostat that includes IR compensation will be used to evaluate this effect on numerous grout mixes. The grout designs tested in this study will include several types of corrosion inhibitors. In previous ACTM studies, some corrosion inhibitors have shown a corrosion accelerating effect which may be due to the nature of the accelerated testing. |
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