Behavior of experimental zinc-steel couples underground

Abstract

The behavior of zinc anodes for t he protectio n of iron and steel cathod ically was investigated in eigh t diverse soil en vironments. The experimen tal unit cons isted of a small steel ring to which was co nnected from one to t hree zin c cylinders to pro vide different area rat ios of zin c to steel. Corrosion of the steel cathodes was prevented over t he test periods of from approximately 3 to 6 years except in one poorly conducting soil a nd in a very alkaline soil. i\feasurements o f galvan ic current and open-and closed-circuit potentials made on the experimental co uples during t he co urse of the te t are in terpreted in terms of the extent cathodic protection rece iv ed. Meas urem ents o f t h e apparen t cu rrent r eq uired fo r cathod ic protection as indicated by current-pote ntial curves are compared wilh the cu rrcnts actually required to prevent co rrosio n.