Sulphate Content Testing
The Testing Process
Sulphate attack is a chemical break down where sulphate ion attacks components of cement paste. Sodium Sulphate attacks calcium hydroxide and forms gypsum that becomes more than double the volume. Sulphate content testing performed in a laboratory can be used to assess sulphate content of samples retrieved from site.
How Sulphate Content Testing Works
Sulphate attack might show itself in different forms depending upon the chemical form of the sulphate and the atmospheric environment the concrete is exposed to.
The consequences of sulphate attack include not only disruptive expansion and cracking, but also loss of strength of concrete due to the loss of cohesion in the hydrated cement paste and of adhesion between it and the aggregate particles. It can be caused by sulphate containing water coming into contact with the concrete. For example, sea water, ground water or sewage water.
