Thaumasite investigation

Thaumasite investigations

 Thaumasite investigations allow us to provide insight a new type of sulfate attack which was discovered in the nineties, initially to the foundations of residential properties but subsequently to foundations of motorway structures; the thaumasite form of sulfate attack (TSA).  Given the presence of carbonates and cold, wet conditions along with sulfates, thaumasite can form replacing cement hydrates in hardened concrete, leading to severe weakening or possible decomposure of the concrete matrix into a white ‘mush’.

Whereas TSA is not common to structures in the UK, preventative measures can be taken should a structure be suspect to this form of sulfate attack.  Due to the conditions required for its formation, buried concrete is more susceptible to TSA.

With direct experience in such works, Nicholls Colton can assist with Thaumasite investigations which will typically include:

  • Visual inspection of exposed elements of a structure.
  • Taking dust samples of hardened concrete for subsequent laboratory testing, typically for sulfate and chloride levels. Such sampling takes place over sufficient depth in the concrete to allow identification of areas at risk from sulfates.
  • Taking cores from hardened concrete for visual examination and phtography at the laboratory subsequent petrographic, X-ray diffraction (XRD) and/or scanning electron microscope (SEM) examination.

Samples for chemical analysis would be tested in our UKAS accredited laboratory, cores for petrographic, XRD or SEM examination being subcontracted to a test house with specific knowledge in this work.