When it comes to concrete, there not much that says “decay” as clearly as exposed, rusting reinforcing steel. Deterioration has significantly advanced when the structure reaches the corrosion point.
Corrosion of the reinforcing steel is a part of a longer process of concrete breakdown, which typically proceeds something like this:
- Stage 1: Concrete ageing, or ASR, or shrinkage, leads to microcracking at the outer layer of the concrete.
- Stage 2: Contaminants enter the concrete through the microcracking, from the surrounding environment, carried by moisture or moisture vapour. These gradually penetrate to the reinforcing zone.
- Stage 3: A corrosion cycle is set up, where the natural passivity of the concrete around the reinforcing is broken down, and oxidation (corrosion) of the steel commences and extends.
- Stage 4: The increased bulk of the oxidised steel causes more significant cracking of the concrete, including delamination and spalling. Often the problem becomes recognised during stage 4. Corrosion stains and increased cracking become obvious and develop into the more serious symptoms.
But that’s not the end of the process.
- Stage 5: The increased cracking leads to the increased entrance of the environmental contaminants, exponentially driving the decay of the concrete towards complete failure.
Sounds drastic? It’s a fact.
Commonly stage 4 is the point where money is spent on a structure, to allay the deterioration and attempt to arrest the process. Patches or coatings may help slow the process by slowing the ingress of contaminants.
However, what is really needed is a treatment to arrest the deterioration and prevent further corrosion.
And this needs to be applied as early as possible.
There is such a treatment. A specialised water-based catalytic treatment is available which can be spray-applied. This treatment utilises the alkalinity and moisture within the concrete to produce a penetrating hydrogel within the porosity of the concrete. Moisture migration in concrete is the base factor that initiates and feeds corrosion, the ‘vehicle’ of contaminants.
The hydrogel binds the moisture within the concrete, preventing the movement of contaminants. No contaminant ingress; no further movement of contaminants into the reinforcing zone.
This is an advanced and effective solution.
If you have the responsibility of upkeep and maintenance of concrete structures, we strongly recommend you are pro-active in addressing deterioration early.