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Fig. 8: Installation of disc-shaped anodes with narrow side toward nozzleman to minimize area behind the anode protection from future corrosion. If repair mate- rials have a resistance higher than 15,000 ohm-cm then a conductive mortar bridge should be used. Alternately, anodes can be placed outside of the repair and connected to exposed steel within the repair area. The use of embedding mortar can also be ben- eficial to prevent shadowing even if the repair material resistivity is less than 15,000 ohm-cm. If no embedding mortar is used, then using thin elongated anodes or installing disc- or oval-shaped anodes so that the narrow side faces the nozzleman will reduce the area behind the anode. David W. Whitmore, P.Eng, is President of Vector Corrosion Technologies, a company which specializes in the cor- Fig. 9: Thin elongated anodes are ideal for shotcrete repairs rosion protection of steel in reinforced concrete structures. Whitmore is a licensed profes- sional engineer and a NACE Certified Cathodic Protection Specialist. He has been an ICRI member for over 20 years and is a Fellow of ACI and CSCE. J. Chris Ball is Vice President of Marketing and Innovation for Vector Corrosion Tech- nologies based in Tampa, FL. Ball has over 20 years of con- struction industry experience with a specialty in concrete repairandcorrosionpro - Fig. 10: Thin elongated anodes installed prior to tection systems. He is a member of ACI, ICRI, shotcrete repair. Installation behind the reinforcing and NACE. bar further reduces cross-sectional area Shotcrete • Summer 2014 19


2014SumShotcreteEMag
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