Electrokinetically deposited coating for increasing the service life of partially deteriorated concrete sewers

Microbiological induced corrosion (MIC) is a leading deterioration mechanism in concrete wastewater conveyance systems. The work reported herein focuses on breaking the MIC cycle by preventing colonization of the bacteria responsible for converting hydrogen sulfide to sulfuric acid. Electrokinetics was used to drive an antimicrobial agent (cuprous oxide) into the porous wall surface of a pre-cast concrete pipe. An electric potential difference, applied between the steel reinforcement embedded in the concrete and a copper electrode placed in the coating solution, provides the driving force to the copper ions. Atomic absorption tests performed on the coated specimens were used to determine the percentage of cuprous oxide that penetrated the porous surface and migrated into the hardened concrete matrix. A pilot study conducted on three mock pipe specimens demonstrated that the process is effective on partially corroded and non-corroded pipes. Test data also revealed that the amount of copper that migrated into the concrete matrix is time dependent. Based on preliminary test results a treatment procedure was designed and implemented on a 380 mm diameter commercial pre-cast concrete pipe. The data suggest that the method could be deployed to “immune” new and partially deteriorated steel reinforced concrete pipes against MIC.