Case 3
Navigation
- Introduction
- Causes of Defects
- Good Practices
- Standards
- Maintenance and Diagnostics
- Remedial
- Similar Cases
- References
Maintenance and Diagnostics
Maintenance
- Reactions of sulphate attacks are not visible to the eye. This suggests that regular inspection on the performance of façade and immediate repair should be done to remedy such defects.
- Suitable instruments and techniques should be used to diagnose defects properly. Diagnosis involves a process in which experts investigate the buildings’ conditions, carry out tests, evaluate, make recommendations for remedial actions where necessary and predict the future performance of a building.
Diagnostics of Defect (see also NDT)
Visual Inspection
A concrete structure suffering from sulphate attack frequently show one or more of the following signs.
- Cracking (bulging or heaving of concrete due to expansion. Cracks radiate from the centre of movement.)
- Spalling
- Etching
- Leaching
- Softening
- Staining
Sulphate attack exhibits a whitish appearance.
Precipitation Method
In the laboratory, sulfate ions are precipitated using barium chloride in an acidic medium to form uniformly sized barium sulfate crystals. The amount of barium sulfate in suspension is then determined by measuring its turbidity and comparing it to a known standardization curve.