NEW TEST methods and assessment procedures for sulfur compounds in structural fill materials have been published by Transport Research Laboratory.
Sulfate specification for structural backfills is the result of work for the Highways Agency by TRL and Sheffield University.
Standard test methods for sulfate and total sulfur are limited and there are no standard test methods for reduced sulfur species such as pyrite, which has been implicated in the thaumasite form of sulfate attack on bridge foundations and corrosion of buried corrugated steel culverts.
New test methods build on existing methodologies and use advances in analytical techniques to allow better characterisation of sulfur.
The report includes assessment procedures for backfill to steel and concrete. TRL said procedures were compatible with existing assessment methods for sulfate content and include limiting values for reduced sulfur species.
The test methods and assessment procedures are compatible with the recently published BRE Special Digest 1: Concrete in aggressive ground .
TRL said the new methods provided a uniform standard approach to testing for sulfur compounds. At the moment, most analytical laboratories used a range of in-house methods, it said.
lTRL Report 447: Sulfate specification for structural backfills can be purchased from TRL Publications, tel: 01344 770783.