We’ll have to start by explaining what we’re doing…
Why does concrete need internal protection?
Concrete is bound together by bonds of molecules (all different shapes and sizes) that form between the cement particles called CSH: Calcium-silica-hydrates.
When you initially cure the concrete, the aim is for strands of these CSH molecules to form as a result of a reaction of the uncured calcium in the cement (found in the form of free lime). However, while the concrete is still fresh, these new bonds are quite weak, and only strengthen over time – this is curing.
Here is an interesting study on the chemistry.
Something that also happens during the curing is that the excess water used in the mix bleeds out, and as the water rises it tends to form passageways within the wet slab, that other molecules follow, and the pores grow larger. The molecules break through the still-weak CSH strands like a scythe, meaning that the end result of the curing is much more ineffective than if the water was immobilised.
It also means that the concrete is left very porous, although the porosities are microscopic. These pores allow moisture to enter and move around within the slab once it is fully cured, introducing soluble contaminants and aiding in the corrosion of the reinforcing steel. This then causes more cracks to occur from within, and the cycle continues. More about that here.
The following pictures resemble how the different components in concrete look when concrete cures, before and after the bleed water has left the concrete very porous.
So that’s why we need proactive protection, so as to ensure that contaminants cannot enter the pores, to prevent corrosion of the reinforcing steel.
So how do we protect?
The AQURON reacts to form more CSH in the pores. Concrete, even aged concrete, usually still has uncured calcium (free lime) available, and this reacts with a catalyst in the AQURON treatment. This catalyst is charged with opposite polarity to the concrete, so it is drawn in like a magnetic force, and is not dependent on gravity. The silica particles bind the relative humidity (moisture that is still within the slab after the bleed water has escaped) and turn it into a gel, called a hydrogel, which eventually becomes part of the concrete.
This is explained by MARKHAM CEO Mark Smith in this podcast discussion.
The CSH that is formed in the gaps, duplicating the concrete itself, is actually stronger than the original concrete. This is thanks to the using nano-silica in the treatment, which is something that contributes to the impressive strength and durability of the ancient Roman structures, some of which are still standing.
This blog will help explain.
Why protect from Day 1?
The reason we believe that Engineers and Architects should specify our treatments in from the planning stage is that the sooner you can take advantage of the moisture and use it to your advantage, instead of allowing it to cause havoc, the better. Moisture can be involved positively; it doesn’t have to be an aspect that constantly sits on your shoulders like a burden, making you worry about structural integrity in the long term.
Simply adding an admixture to your concrete with the pour, or spray-applying it afterwards during the curing phase will ensure you can add years to concrete service life!
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Or if you want to talk to someone to get started, please get in touch!