Abstract
Following the discovery of severe corrosion of cadmium plated steel bolts in an underground irrigation system, the corrosivity of the surrounding soil and ground water was assessed using the procedures outlined in the standard DIN 50929. This methodology predicted successfully the strongly aggressive nature of the soil from the irrigation system, which contained sulphate reducing bacteria, although the corrosivity of the ground water was low. An evaluation of alternative bolting materials was conducted using both soil from the irrigation network and soil of lower corrosivity from a university campus in Athens. This has shown that general corrosion rates for screws made from type 316 stainless steel or brass are much lower than those for ferritic steel or similar steel coated with cadmium or zinc. However, the brass and stainless steel screws both showed evidence of localised corrosion (pitting and dezincification respectively).
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