Taming the beast

Concrete cancer is a destructive beast that ravages the construction industry.

Why?

This problem is caused by the ‘water of convenience’ or ‘free water’ in concrete that is not required for hydration, but is necessary for mixing, placing, levelling and the finishing of concrete.

How?

This bleed water is lighter than other materials in the concrete matrix, so it floats to the top. 

In any piece of concrete, in most applications, millions of tiny bleed water tubes called capillaries are formed, that stay in the concrete once it has set.

Concrete is the most stable of all construction materials but, because of these capillaries, it acts like a sponge, allowing the ingress of water and destructive chemicals. 

When these liquids reach the steel, the pH - that was at 12 when the concrete was poured - drops to as low as 7, destroying the structural steel. The steel rusts, the concrete around it expands and spalls. 

This contributes to catastrophic failure – and it’s a beast to the longevity of any structure.