The effects of storage conditions on the sulphur speciation in geological material

Abstract

The corrosion of galvanized steel buriedstructures and the deterioration of buriedconcrete structures are problems attributed to the presence of sulphate and sulphide species in the structural backfill and natural ground surrounding the buried structures. Avoidance of these problems depends on reliable chemical testing of samples of the materials in the first instance. However, the results of tests may be incorrect because of oxidation of sulphur minerals during sample storage. Results are presented in this paper of aninvestigation carried out into the effects that different storage conditions have on the sulphur species, particularly oxidation of pyrite and growth of gypsum. The findings show that pyrite oxidation will occur withinstorage periods of weeks to months affecting subsequent chemical test results for sulphur species. In this paper guidance on suitable storage and testing protocols is provided.