Procedures for assessing thaumasite sulfate attack and adjacent ground conditions at buried concrete structures

Abstract

Abstract In 1998 Halcrow were appointed by the Highways Agency to investigate the thaumasite form of sulfate attack at the buried concrete foundations of structures on major highways in Gloucestershire, UK. Detailed investigations were completed at 28 structures and the results used to apply a risk assessment procedure to a further ninety structures. Standard procedures for sampling, testing and classifying soil, groundwater and concrete were devised to ensure that rigorous statistical analyses of the data could be applied. The procedures were also designed to meet the then current UK guidance notes, BRE. Digest 363 [Building Research Establishment, Sulphate and acid resistance of concrete in the ground, BRE Digest 363, CRC Press, Boca Raton, 1996] and the Thaumasite Expert Group Report [Thaumasite Expert Group, The thaumasite form of sulfate attack: Risks, diagnosis, remedial works and guidance on new construction, DETR, 1999] and are compatible with the subsequent BRE Special Digest 1 [Building Research Establishment. Concrete in aggressive ground, Part 1: assessing the aggressive chemical environment, BRE Special Digest 1, CRC, Boca Raton, 2001]. Recommendations are made for applying many of the procedures that have been developed to future site investigations to enable consistency, compatibility and easier data transfer for future research on the thaumasite form of sulfate attack.