Demonstration and Validation of Controlled Low-Strength Materials for Corrosion Mitigation of Buried Steel Pipes: Final Report on Project F09-A17

Abstract : Researchers investigated the use of controlled low-strength materials (CLSMs) to reduce the corrosion rate of buried steel structures. These thin, self-consolidating cementitious materials, also called flowable fills, have an alkaline chemistry that could promote rapid passivation of buried steel surfaces. Two different CLSM blends were tested. Both used cement and a flowability admixture, but one used native soil instead of standard fine aggregate. Using six prepared bare steel pipe specimens, six pipe beds were prepared to evaluate the corrosion-mitigation effects of the two CLSM sused both with and without galvanic cathodic protection (CP). Two control specimens were backfilled using native soil, with and without CP. Commercial probes and instrumentation were used to monitor the specimensfor 13 months, logging linear polarization resistance and electrical resistance data for post-exposure evaluation. After excavation, the specimens were also visually inspected for corrosion effects. Results indicated that both flowable fill materials, as used with CP, can effectively mitigate corrosion. Isolated corrosion cells formed where the pipe support pads for the soil cement specimens were improperly installed, resembling isolated corrosion that also appeared on flowable fill specimens without CP. The calculated return on investment for this project was 3.89.