Hypersaline Water

and its effect on concrete

Saline”, of course, means salty; and is often used to refer to a solution of salt in water.
Hypersaline” is a technical term referring to water which is saltier than typical sea water.

How does this involve the mining industry?

“As part of the water management program, water is also sourced from tailings dam return water and from bore water. This hypersaline water contains about five times as much salt as sea water.”Water Corporation education sheet

Hypersaline water occasionally hits the headlines when it inadvertently spills out of its regular containment, contaminating neighbouring environments or farmland. The ultra-high level of salt in the water makes it an aggressive, reactive pollutant.

Challenging to concrete

For this reason, when we are working with mining infrastructure, we are often asked about protecting the concrete involved in containment or channeling of hypersaline water.

It is well known that high chloride levels in solution are a serious challenge for concrete. They destroy the passivity of the rebar zone within the structure, leaving it vulnerable to rebar corrosion and the consequent spalling and deterioration.

Where have we seen this before?

The quote above, from the Water Corporation, mentions sea water. Yes, the same challenges are found in the marine environment. While the concentrations involved in hypersaline water are much higher, the principle is the same: water enters via the micro-porosity of the concrete.

If you can block that porosity, moisture cannot enter at all. This means that, regardless of the salt concentration, the concrete is protected internally.

How is this possible?

And as a result of both in-house testing, external project studies, and extensive on-site anecdotal evidence, we would like to tell you that a hydrogel waterproofing admixture is an extremely effective means of protecting concrete against chloride contamination … and thereby saving long-term unplanned costs.

Waterproofing concrete using hydrogel admixture

Here’s the technical overview:

Hydrogel treatment is a liquid, added to the mix water during the batching process at the supply plant. Combined with the mix water, it is evenly distributed throughout the batch. The cement in the mix then causes the treatment to interact with the water and a hydrogel is formed throughout the concrete. The water, now being in a gel state, is able to maximise the saturation of every cement particle – so essential for uniform hydration. After placement, the hydrogel solidifies within the pore structure to minimise moisture loss during the curing stage and prevent ingress and migration of water and common debilitating substances throughout the life of the concrete.

The benefits of hydrogel waterproofing admixture include

  • 1 – WATERPROOFING by immobilising of the moisture content and preventing further ingress.
  • 2 – IMPROVED CURING by controlling the hydration – giving a more durable concrete.
  • 3 – SHRINKAGE REDUCTION – reducing microcracking during curing, and therefore removing entryways for long-term contamination.
  • 4 – SELF HEALING – a hydrogel treatment continues to be effective for the life of the structure, reacting to ambient moisture levels, and sealing non-moving cracks up to 0.5mm.

It also happens to be nil VOC, and improves the concrete handling, making placement easier.

The treatment is extremely safe for the environment, besides reducing the need of new concrete production, through enhancing service life.

Sounds relevant? Want to talk? Get in touch!

Your structure was poured years ago? Don’t despair, MARKHAM also offers remediation treatments! And you’ll be interested to know, it is possible to test concrete chloride levels, thereby monitoring the effectiveness of the treatment.

Hero image: Central Norseman Gold Mine

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