Polarisation resistance data provide critical constraints for estimates of structural integrity based on corrosion rates in soil. However several pitfalls have been identified in the application of standard electrochemical methods. Packing fractions, moisture, and galvanic resistance must be assessed prior to subjective Tafel analysis. Better results can be obtained using a transient galvanic pulse with numerical modelling of the observed response. Multiple determinations for a bentonite synthetic soil indicate drift in Rp values consistent with water content. Weight loss methods confirm the associated corrosion rates assuming general oxidation but a ten-fold increase is required where pitting is significant.
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