Report 447 Sulfate specification for structural backfills

Publication Year

2001

Document Status

Withdrawn

Abstract

Problems have been experienced on recent highway schemes with corrosion of galvanised, corrugated steel buried structures (CSBS) due to chemical reactions from structural backfill. The corrosion has been attributed to the presence of sulphates and sulphides in the selected fill, which were not detected under current testing requirements. More recently, problems have arisen due to the thaumasite form of sulfate attack on buried concrete in bridge foundations. A review by TRL (Unpublished Project Report PR/CE/ 169/96) indicated that improvements could be made in the identification and assessment of sulphur compounds in the current Specification for Highway Works (MCHW1) and related documents. The present project was undertaken to develop appropriate test methods for sulphur compounds in structural backfills, to determine appropriate limiting values for the various sulphur compounds and to prepare. modifications to MCHW1 and related documents. This is the final project report and contains the proposed test methods, limiting values for sulfate generated by oxidation of reduced sulphur and modifications to the relevant sections of the MCHW and DMRB.

Document History

Superseded by the 2005 edition.

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