It’s possible to argue that there’s not really any such thing as unprotected concrete. To start with, concrete is innately durable; and industry improvements on mix designs are actively focused on long-term structural life spans. Strictly speaking, concrete can be produced which is more or less self-protected against the daily conditions to which it will be exposed.
However, there’s a broad spectrum of reasons why designed life is rarely reflected in real life.
This article is not about those reasons, but to simplistically run through the deterioration process as it typically happens when no early protection is undertaken.
Number 1: Unprotected Concrete Lets in Moisture
Concrete is porous, and some moisture movement will always occur. Yes, mix designs which focus on durability and strength will produce a much less porous concrete. But no, it will still let in moisture (including moisture vapour), and moisture will move about within.
Moisture is a vehicle for many deleterious contaminants… little part-molecules of reactive elements are dissolved or suspended in the moisture, and carried along, into and through the concrete. These include obvious contaminants such as chlorides and sulphides and not-so-obvious reactants such as carbon dioxide.
Some of these reactive substances operate on the concrete itself, setting up the downward spiral of ASR or carbonation. Others may reach the ‘rebar zone’, the protective area of passivation around the reinforcing steel, and set up corrosion.
Number 2: Unprotected Concrete Cracks
ASR, steel corrosion and other issues will cause cracking. It’s the next step in a spiralling cycle of deterioration. The expansion of the corroding steel will rapidly accelerate this damage. What follows is that the cracks allow more moisture-borne contamination into the concrete, and the driving causes of the cracking are worsened.
Number 3: Unprotected Concrete Falls Apart
Unremediated cracking will worsen to the point where the concrete is de-laminating or spalling away from the corroding steel.
Somewhere between Number 2 and Number 3, there’s usually an attempt made by the asset owner to fix the problem. Without dealing with the underlying cause, these attempts have mixed results.
Concrete can be Protected Early!
There’s no need for this deterioration cycle to prematurely age your concrete assets.
SEAL the porosity of the concrete and IMMOBILISE the moisture so it’s not transporting contaminants!
This is where MARKHAM spray-applied penetrating hydrogel treatments really shine. The catalytic action of the treatment sets up a process that uses the free limes within the concrete, immobilizing the moisture into a hydrogel formation within the pores. It’s a comparatively simple process, but enormously effective, with far-reaching benefits.
In the case of exposed concrete, even in demanding marine or toxic environments, hydrogel treatments have been proved to provide greatly enhanced durability and extend structural service life.
Get in touch if you’d like more information – case studies, technical data or discussion about your particular concrete structure!
