Is faster better?
Well, high temperatures do force rapid curing. There’s no doubt everybody wants things sooner than ever before. With increasing time pressure on precast production lines and construction sites, it may be tempting to hurry the curing process. However, concrete being cured too quickly, particularly under hot ambient conditions, can result in inherent weakness.
And it’s those hot conditions we’d like to talk about now.
Doesn’t heat help the curing process?
As noted, heat may hurry the curing process. This doesn’t mean it’s helping.
Problems can readily result both internally and on the surface.
Within, the concrete may cure unevenly over time. This can result in voids, internal weaknesses, and excess free limes within the concrete. Delayed curing can lead to cracking later in the structure’s life.
On the surface, the most noticeable effect of excess heat is shrinkage cracking. Caused by excess evaporation at the surface, this is so common an occurrence in warmer climates that it is frequently ignored altogether.
Shrinkage cracking isn’t a big deal, right?
Not at first, no. It can be unsightly if extensive, but there are many situations where that doesn’t matter.
HOWEVER, micro-cracking is the start of a long-term cycle of deterioration, a driver for premature decay of the concrete.
Here’s what happens: major cracking is caused by reinforcing steel rusting, or by internal expansive concrete reactions such as ASR. Those processes can’t happen by themselves – they are driven by contamination such as chlorides and other salts. These contaminants travel and react because they are soluble in water – they do not react if totally dry.
Guess how the water gets in? Via microscopic porosities and cracks.
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LITTLE CRACKS CAN CAUSE BIG CRACKS, AND BIG CRACKS KILL CONCRETE.
Hence – there is a direct correlation between poor hydration during curing, and premature deterioration.
Further – high ambient temperatures have a negative effect on hydration quality.
Therefore, these high temperatures during construction will threaten the effective service life of the structure.
Protect the concrete from Day One, right?
So, we understand that the concrete needs the protection of thorough hydration; and that’s a very significant challenge on hot days.
‘Water curing’ has long been the traditional method for maintaining surface moisture. This is not necessarily practical in a precast environment. Curing compounds or coatings also have their drawbacks. They are usually intended to break down after the event, in ultraviolet light; however, there is often residue long after that break-down should have occurred, and this will need removal.
Presenting … hydrogel treatments!
There’s an advanced alternative which is simpler, more versatile, and often cheaper. The application of nanotechnology catalytic silica will induce the formation of a hydrogel within the porosity of the concrete. Sounds complicated? It’s a simple spray-on process with minimal fuss or interruption to workflow.
Hydrogel treatments and civil infrastructure precast elements
If you’re involved in the maintenance of civil infrastructure, including concrete structures, you may be aware that hydrogel treatments have been used for many years in Australasia for remediation and rescuing service life.
However, it is much more cost-effective, taking the planned service life of the structure into account, to protect all the concrete elements from the outset – at the precast and construction phase.
De Sitter’s Law of Fives applies. The earlier you invest in intelligent maintenance, the less the overall cost will be over time.
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How do we incorporate hydrogels into the construction?
There are two methods which will assist both hydration quality and long-term durability.
Hydrogel waterproofing admixture has multiple benefits. It is a superior alternative to crystalline admixture technologies and improves ease of handling. Improved hydration is just another of its many advantages. For more information, here’s a quick overview.
Spray-applied hydrogel treatment is the original and most popular approach. Its curing qualities are equal or superior to 7 days’ water curing (test results available). The resulting concrete hydrogel penetrates to 150mm depth, protecting reinforcing steel, immobilising moisture, waterproofing the concrete, and bonus anti-dust hardening benefits are thrown in.
And there’s more. Oh, there’s more.
Hydrogels are amazing and cover a range of concrete needs: waterproofing, anti-dust hardening, long-term durability.
Intrigued? Faced with a new project or a concrete maintenance challenge? Get in touch!
