Why is impermeability significant in concrete?

LOUISE: Well hello all, and welcome to Markham’s latest podcast episode. I’m Louise Kirk, part of the Markham marketing team in Australia and it’s great to have you listening today.

Continuing our Invisible Strength series today we will be discussing the factor of impermeability in concrete. Why is Impermeability Significant in Concrete? We’ll also be talking about concrete floor slab issues under floor coverings.

With me today is Nikki Horn, our New Zealand Project Manager. Nikki joins us from the Markham headquarters in Napier, New Zealand. Nikki, welcome aboard and please introduce yourself to the audience!

NIKKI: Thank you, Louise, for that awesome introduction. So, as Louise said, my name is Nikki. I have been at Markham for two-and-a-half years now – time flies! So I started here as the project management assistant and got promoted, went up the ranks to project manager. I have a medicinal chemistry and business background, so a little bit different from what I do here.

LOUISE: Oh thanks, Nikki! And connecting from our Sydney office we have Wade Lanham, one of our experienced project consultants. Wade tell the audience about yourself!

WADE: Yes thanks, Louise! Yes, my name is Wade, I work out of our Sydney office. Look after most of the east coast of Australia. I’ve been with Markham for around three years. What’s interesting about that is, we were a fairly small company back three years ago and we’ve really gone through some rapid growth. So it’s been really good to be part of that growth and looking forward to what comes in the future as well.

LOUISE: Well, thank you, Wade! Could you launch us into our topic by explaining how impermeability is addressed in the industry?

WADE: Yeah, it’s an interesting topic, when we’re talking about impermeability in concrete. It’s something that affects quite a lot of different aspects of concrete, from contaminants getting down into the concrete – from moisture getting through concrete – even quite a lot of water coming through if we’re talking about something like a basement situation. There are lots of different ways that people try and deal with this. It can be membranes and types of things like that cut off water from getting into the concrete. It can be camouflaged in strength ratings. A lot of people believe by upping the strength rating in the concrete that you’ll actually make it less permeable.

There are lots of different things that people use, such as flyash in mix designs, but there’s lots of different complexities in trying to battle these type of things. So yeah, it essentially what people are trying to do is make a denser concrete to try and combat the situation.

LOUISE: So what you’re saying is that people are talking about making concrete stronger, and they are actually making it less permeable.

WADE: Yes, in some cases they are and that’s what we want to try to achieve. If we can make a denser, stronger concrete – for one it lasts longer so we don’t have to wreck these structures earlier, but a lot of the contamination that does damage to concrete is carried in by moisture. So if we can reduce the moisture getting into the concrete we’re actually going to make concrete last longer naturally. And yeah, prevent us from using so much of it over and over again.

LOUISE: And is there a better method of doing it than just flyash? Nikki, could you help us about this? What’s your recommendation?

NIKKI: Thanks, Louise. I personally don’t have a lot of experience using flyash. There is a global shortage of flyash actually. This comes down to a couple of factors – the poor quality of flyash from some different places, and it’s very expensive to import because it is so bulky, and we are making less and less of it due to the environmental impact of burning coal.

One of the solutions that I often utilise is the hydrogel treatment, and I prefer it over flyash because it can be better for the environment, and it enhances self-healing and closes up all of those porosities, to make the concrete more impermeable.

LOUISE: That’s very interesting! That point you mentioned about immobilising the internal moisture leads us to our further topic, I think, about concrete slabs under floor coverings. Can you give us an overview? A drone view of issues you see in the field?

NIKKI: Yes I can. So as we all know, construction schedules are very tight. There never seems to be enough time or enough money, and time is money, unfortunately. When you do use a hydrogel treatment, the slab becomes trafficable within 24 hours. You can load up that slab with materials, which is really great. Traditional methods of curing like ponding and blankets slow down progress. Of course, you can’t get other trades on those slabs for 7 to 14 days, which is really not ideal when you are trying to make up time lost in construction. Quite often, what we do is we recommend 28 days between your hydrogel treatment and putting down the floor coverings. With the immobilised moisture within those pores from the hydrogel, as long as your floor prep is up to scratch, you can guarantee the floor coverings regardless of the E96 or calcium chloride testing and RH readings.

LOUISE: So Nikki, to summarise what you’ve said: immobilising the concrete’s internal moisture with hydrogel treatments will prevent any moisture adhesive issues with floor coverings?

NIKKI: Yes. So Markham has been using hydrogel treatments in this way under floor coverings for nearly 25 years. We’ve used it in aged care facilities in both Australia and New Zealand, and some big reputable companies like Ryman, BUPA, Summerset and Arvida. We’ve used it in schools and one of my favourite examples is the “277 and 309” development for Westfield in Newmarket, New Zealand. Our CEO has this great video of him walking through the mall itself and looking at all the tenancies, and every single one of them has a different flooring type, whether it’s carpet, tiles, vinyl, and you can see there that with a hydrogel treatment underneath, there are no issues with any of those floor coverings. And it’s a great video – when he walks past, you see the flooring types change and it just is really incredible.

LOUISE: Can you share any specific examples? Any case studies that stand out in your mind?

NIKKI: Yeah, I can, thank you! Mark and Graham have this awesome story about a local job where we utilised the AQURON hydrogel treatment. So it was about 20 years ago and we … it was an existing slab. We treated it with the AQURON hydrogel, and it was sanded and prepared for floor coverings. Now about three or four weeks later, all of these little bubbles turned up all over the slab. It was really, really strange. And so Mark and Graham went to look at it, and they determined it was not a moisture issue as thought, it was a full preparation issue. Upon lifting up the flooring and areas with those bubbles, you can see that there was almost a divot in the slab that had allowed the AQURON to pool on the top of the surface, meaning that it didn’t bind with the adhesive on the floor covering. These little divots were actually the footprints of the person doing the floor preparation. As they rocked from side to side with the sander they had left these little divots and obviously, the sanding didn’t take off enough of the slab or the top of the concrete to get rid of these divots.

So essentially Markham put their money where their mouth is, and said “Hey, if you replace these floor coverings, and re-prep the floor and don’t re-apply the AQURON and it fails, we will replace not only at the cost for the flooring replacement, but the initial one as well.”

So they had so much trust in the product and the process that they really, you know, put their money where their mouth is, to re-use that phrase.

So that’s exactly what happened. They took off the floor coverings. It came off two-inch strips except for the areas where those bubbles were, because it was such a strong bond between the adhesive and the concrete, except in the areas where these bubbles were – that came off very easily, because that bond was not there.

Now, this concrete actually had an RH of 90%, which really shows that despite the presence of all that moisture in the concrete, the hydrogel had immobilised it and made that slab impermeable. So the floor was re-sanded and re-prepped after the floor coverings had been removed and no AQURON was re-applied, and the floor coverings went back down. That was 20 years ago and there have been no issues there since. It’s a great testament to, you know, the trust that we have here at Markham in our products. And it’s just one of those great learning experiences for the team here as well.

So this is why Markham has our flooring installation guide that comes along with our products and why we also stick to a supply and apply methodology for hydrogel treatments under floor coverings.

LOUISE: Wow, that case is almost hilarious. How do you find it, Wade? You’re seeing the same sort of issues on construction sites?

WADE: Yeah I am. It’s funny because I tend to deal mainly with new construction. In new construction we see other challenges as well as these challenges that Nikki mentioned. There’s things like curing and moisture control, and there’s lots of different elements that go into it a new build.

So by using these hydrogel treatments we actually knockout what would normally be multiple sections of a build in one hit and it goes down the night of the concrete pour.

So we’re covering things like curing the concrete, moisture control in the concrete, densifying the concrete and, in some cases even urine barrier in those age care situations.

So what would normally be a multiple part of the build is actually all knocked over really quickly. The good thing about this is it’s not just the cost-saving of products in these situations, but it’s the massive time saving for that construction team. I think we mentioned earlier that time is money. So by being able to cure the concrete with the same product the night of the concrete pour then being able to load up all their gear for the next day onto that slab … you can actually lay floorings after just 28 days on fresh concrete, the flooring contractors don’t have to worry about their moisture control. They don’t worry about warranties for that it’s all covered under the Markham warranty. So there’s many, many different benefits that save you massive amounts of time and money across these new builds.

LOUISE: Definitely a win-win solution.

Well, thank you so much Nikki and Wade for joining us today! And to all our listeners, we welcome any questions or feedback that you have on today’s topic or even if you have a specific project you would like to talk about.

If you want to find out more, please go to our website www.markhamglobal.com. We do our best to respond to all inquiries within a business day. We’re also happy to take suggestions for topics in the future. Tell us, what are your concrete pain points in the field? How can we help to educate the industry?

Thank you so much for listening and don’t miss our next episodes.