total potential sulfate

Technical Note: What is total potential sulfate?

Definition and Background

Total Potential Sulfate (TPS) represents the chemical equivalent of the maximum sulfate that could be theoretically generated if all sulfur within a sample of a geological material (e.g., soil, rock, aggregate etc.) was to oxidise.

TPS is determined as part of the assessment of sulfur-species, in combination with determination of water-soluble sulfate, acid-soluble sulfate and total sulfur. This conversion has been used since at least the late 1970s (e.g., Nixon 1978, Wilson 1987) and is now found in most UK guidance, having been formalised in BR 279 (Bowley 1995) and used in the M5 motorway thaumasite investigations (TEG 1999).… Read the rest

Research Paper: Derived chemical terms for sulfur-species assessment

derived chemical terms

Tom St John (University of Bristol) has published a paper on the use and limitations of derived chemical terms for assessing sulfur-species in ground materials. The author considers a wide range of derived chemical terms used in the literature, such as equivalent pyrite and total potential sulfate and the limitations involved in their application.

The paper is titled “Use of derived terms for sulfur-species in geological materials”.


“An assessment of the sulfur/sulfide content of ground materials for civil engineering purposes is essential in order to understand the potential for sulfate development. In the absence of detailed petrographic/mineralogical data, terms such as “total potential sulfate”, “oxidisable sulfides” and “equivalent pyrite” are often derived from sample test results for total sulfur, water-soluble sulfate and acid-soluble sulfate.
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