Replacing thermal sprayed zinc anodes on cathodically protected steel reinforced concrete bridges: Experimental and modeling studies

摘要

This research aimed to address questions underlying the replacement of arc-sprayed zinc anodes oncathodically protected steel reinforced concrete bridges and to develop a protocol to prepare the concretesurface for the new anode through a combination of laboratory test and modeling studies. To achieve stronginitial bond strength of new zinc to the existing bridge concrete, the current operating configuration (#8 nozzlewith high sand volume) is too aggressive and should be changed to #6 nozzle with low sand volume to achievetarget RMS macro-roughness of 1.2-2.1 centi-inches and micro-roughness of 0.014-0.02 centi-inches. It isrecommended to adjust the anode removal and surface profiling based on the electrochemical age of theexisting concrete. Wherever possible, large aggregates (e.g., diameters ¾ in. and bigger) should be avoided forexposure by surface profiling. For non-electrochemically aged concrete, profile the surface to achieve a RMSmacro-roughness of 1.1-1.8 centi-inches and 5-36% exposed aggregates. For existing concrete with relativelyhigh electrochemical age (14 yrs), profile the surface to achieve a RMS macro-roughness of 1.1-1.5 centi16inches and 44-55% exposed aggregates.