PSD Residential Flooring

a solid base for the future

Sulfate Attack........................... page 1 | 2 | 3

How to recognise typical damage from sulfate attack

Expansive sulfate reaction within the concrete floor slabs will tend to produce horizontal expansion of the floor slab or oversite concrete. However, these are generally constrained at the perimeter, where the concrete abuts external and internal walls. As a result the slab or oversite concrete is typically uplifted into a dome shape which, with time, may achieve a deflection of several centimetres. The doming will put the upper part of the concrete element into tension, leading to a map pattern of cracking. This cracking may penetrate through floor slabs, or be confined to the topmost 'screed' layer, which often comprises a much weaker mix of sand and cement, 25-35 mm thick.