Specialised admixtures for control and durability

BRENDAN:

G’day and kia ora, everybody, wherever you’re listening in from Glad to have you on board. It's Brendan here, and we've got Doug and Hayden with us today on this live event - Specialized Admixtures for Control and Durability. And what I'm going to do right now is share the slide deck. I promise you, it's not death by slide deck; it’s a very short one today.

So can everybody see that all right? And please let me know if you can't hear. So the agenda covers the benefits of specialized liquid admixtures for batching plants, and for site teams, and for the asset owner. So it's a win-win-win situation we'd like to talk about.

And Hayden and Doug you've probably met before, particularly if you've been on our previous events. They’re based in the Napier offices in New Zealand. They'll introduce themselves as they join the conversation. And you can submit your questions at any time on the chat or question tabs. So that all helps with the flow of the conversation as we go along.

And we've got a question for you. You can put your answer to this at any time, but we're going to circle back to it right at the end of the session: What's your number one challenge in concrete production or construction? So if you could give that some thought. We'd like to hear about it a little later on. Hayden, I think you're going to take us away on this.

HAYDEN:

Thanks Brendo. And yes, good morning, good evening, wherever you’re streaming in from. So yes, good to be on another one of these. And like Brendan said, Hayden Prestidge, out of the New Zealand office.

But that question's interesting. What's the number one challenge in construction and production of current ready-mix? And it's a question we’ve been going around asking, probably for the last three months or more, of all the major players in the industry, ready-mix and in the construction side. It's been very interesting that there is a change in scene in concrete; and obviously this drive towards greener, you know, reduced carbon etc, and it is changing dynamics, changing thoughts.

And whether, you know, we’re keeping up with the play; and whether there's systems that we don't know about that can help us get better etc. So yes, keen to be part of this session. And as always, we love questions. That's where the magic happens on these sessions. More interaction and real chat. So keen to just keep those busy as we go through.

But yes, just wanted to really to talk about the realities of a changing industry and just dive into a couple of these points of what we're seeing. Obviously, we've got... and some of you will be familiar with this from our past webinars and things - but we've seen a little bit of disconnect between those setting expectations and milestones etc - you know, governing bodies, authorities, even companies chasing green star etc. But then, what that means, the disconnect between the actual people on the ground working with the concrete, producing the concrete, placing the concrete, those expectations are different. It’s a different product coming through. You know, we've got cement replacements, etc; it doesn't behave exactly the same as “good old GP concrete” as we hear it in the industry.

So a lot around the batching and placement, there's quite a bit of difference we’re seeing in reaction times, you know, strength, development, bleed, workability, open life. You know, how long we've got, that slump retention, all those sort of things are changing scenes. And we may not be familiar or trained on how to deal with this new product coming through.

The consistency of performance has been a topic. It's quite interesting, going through Australia, New Zealand, UK as well. Are we matching consistency? Are we getting the same every time - the same results? So it's been a good topic. And then there's some lingering concerns around the durability. You know, these new mixes.

What happens in 5, or 10, 20, 50 years time, when we’ve got a whole lot of cement replacement? Are we 100% sure that we're going to meet the design life? So that's some of the things that we're seeing. We’re interested in those on the call, what you're seeing as well, the real realities of the changing industry. But I think we can all agree it is changing. So let's be up to date with what's some good principles and good practices to make it better.

So - handing over to Doug Hamlin.

DOUG:

Thanks Hayden. Yes, and I guess just on that, the overarching, or ... Overall it's a very positive move the industry is making to, you know, reduce the carbon footprint. Obviously cement is a very high contributor in the space. And, you know, overall that's very positive. It's just these few challenges and things that need to be addressed so that the market as a whole jumps on board and, you know, starts using these concretes.

So yes, I'm Doug Hamlin, I've been with MARKHAM about 14 years now. Based alongside Hayden in the new Zealand office. The last webinar, we got a few bits of feedback around focusing on specifics; you know, specific products for challenges. What are the actual problems we solve, as such?

So what we've done here is listed out some of the main ones that we're working on - that we're working with clients on - for your benefit so you can, you know, start thinking about, whether there's use in your... whether you're a ready-mix supplier or whether you're a government department, council or whatever it may be; trying to achieve these low carbon numbers.

So, yes. First of all, starting with the use of slag. So the issues around with slag cement is typically low early strength. So it takes a while to react and hydrate, and start forming that calcium-silica-hydrate; versus your standard Portland GP cement, which is acting much faster, and that's what everybody's used to. So, you know, whereas a normal cement, a GP cement, you might be able to strike your formwork, or life your precast panels, on day one. It could be pushed out somewhere between 1 to 3 days with slag. So, you know, to boost that early strength, and keep that... ensure that durability stays there and also that the workability of the product as well.

So that kind of flows into that next point there. Some of these mixes do become different, harder to place, depending on who you talk to. They do behave differently. So they do bleed at different rates, different times. They may not be as easy to pump and place. So looking at enhancing that workability through an admixture, making it act as close as we can to a standard GP concrete. Waterproofing and durability, so much the same as you would in traditional construction.

So being able to increase things like the chloride resistance, the resistance to water penetration in the concrete, you know, pushing that service life out as long as possible, stopping moisture getting to the reinforcing steel. Pump aid is another area there. So when you're pumping, maybe height, you know, decent height, or over long distances, to be able to keep that concrete together, and cohesive, but also so it pumps nicely; and you're not having to wind the pump pressure up and put your pumps and your gear through duress there. So being able to increase the lubricity of the concrete, so that, you know, it places more like a standard concrete there, or better. It makes life easier for everybody, which we'll touch on in the next few slides.

With calcined clays - so that's a reasonably new... it has been around for years, but hasn't been really looked at due to costs and things. It’s starting to become more of a topic now. But it is very water hungry, so it does increase your water demand which obviously has impacts on your workability, strength gains, all those things. So we're looking at... we’ve got options there to increase that workability and make sure we're not losing any of that performance there.

Silica fume replacement. So silica fume is becoming more scarce. There's also issues around how it's handled at the plants. So it's got safety concerns being a powdered silica product. But we're looking at whether we can replace that with a liquid admixture. Lots easier to handle, safer to handle. And, you know, more consistent in terms of how you can dose it on-site.

H₂S resistance is an interesting one there. So obviously with some of these concretes, particularly slag, you are getting a high durability concrete. But we've been able to improve that even further and get that durability earlier on than you would. So you're not having to wait till your 56, 90 day, time period to be able to get those average strengths and usability of the concrete. Fly ash replacement. A few issues there, particularly around with the closing of coal fired power stations and things, we are looking at alternative sources now.

So things like pond ash; older, lower grades of fly ash that were typically dumped are being reused now, or pulled out of the ground. And there are some issues here with activation of this. So it's not as fast as the higher grades. So yes, whether we can essentially increase their reactivity from earlier on and get that product used in concrete because it does have, you know, that low carbon benefit.

And lastly the efflorescence. So this is more around bricks and masonry production. So particularly when you're doing, you know, more vibrant sort of darker colors - having issues with the salts coming out of the concrete and causing visual markings, that type of thing. And now that, you know, to stop that and getting a more consistent, high quality product, which obviously over... has the initial visual benefit, but being able to stop that happening right from day one gets a lot... You get a longer lasting product as well.

So that should give you a brief overview of some of the areas we're looking at. It is extensive and there's a lot of, you know, different pieces to the puzzle here. But yes, that hopefully helps in outlining some of those there. Over to you, Hayden.

HAYDEN:

Thanks, Douglas. Agree. It's... they’re probably the main things that we've had in our conversations. So I'd love to hear from anyone on this call, if there's anything else that's pressing. Or if that resonates, and in what way. That would be good. But now we just want to focus in on the batching side, the actual production of ready-mix and some of these newer mixes and how the colloidal silica liquid admixtures are helpful in this thing.

And I really want to bring it down to two areas - or one really, is your reduction of risk. There's so much pressure on ready-mix producers. And they’re carrying a lot of weight as far as the risk goes. And how do we get that into the best position so there’s a reduction of risk?

But where we're relying on some others to take on some of that space and ease that pain. So what we're really seeing is, quality control is a big one. Safety. Safety, first of all, we'll go there. So there's a lot of powders. And obviously, cement is the bad boy in the industry. But being the crystalline-type powders, you know, for... just purely for the labour of putting product in. How are we controlling that, and how are we maximizing our safety requirements there?

And then quality control as well, we want to really dive into next. It is important, you know, we may have to manually... those products, when we have to, you know, back up to a different stand, put in powdered products, put in, you know, different bags, etc. Are we really capturing those processes right? And do we know what's actually going in the mix?

You know, 2am in the morning when the trucks are coming thick and fast and pours are going crazy. Are we getting it right? Versus a liquid-type admixture that can be plumbed in and through the batching system and just comes up through mixes. And it's all recorded on your data and your batching sheets, etc. So it's a real key point there.

And then just the simplicity of it really, which probably ties that together, you know. We’re really finding we’re having some good feedback in the industry of liquids versus powders, you know; the ability to move, store, batch, those sort of things; the safety of them, and then getting them into the right place. So is there anything else to add on that one, Doug, do you think?

DOUG:

No, no, that’s covered it well, thanks. Over to you, then, on what the site teams get. Oh, yes. So as Hayden mentioned, there's obviously the safety and simplicity of batching; that type of thing. That really extends in principle to when you're placing on site. So with these types of admixtures, you're not seeing the same workability issues, not seeing the sticky concrete.

We've heard a story recently, about a site team having a high SCM mix, and literally getting stuck in the concrete with their gumboots, not being able to, you know, move around. So that's not good when you're trying to screed and rake and place the concrete, level the concrete. So what colloidal silica does - fastening on that type of admixture for now - it helps retain that moisture in the concrete. So it makes it more lubricated, essentially. So you're not ... your moisture isn't being taken away...

So if you've got, like, a powdered admixture which would draw the water away from the mix and make it drier, more sticky, these admixtures, they are liquid to start with. So they've got their own moisture, so to speak. And then once they're mixing in the concrete, they actually retain that moisture within a type of a gel. And what that's doing is essentially setting up more cement paste within that concrete in those early stages. So it makes it lots easier. Everybody knows if you get a high-cement concrete, you're getting a much creamier mix to work with.

And that's what we're seeing with these admixtures. So you're getting... it’s a lot easier to place. Especially where you've got things like high micro-silica doses, that type of thing. And then some of these slag concretes have similar issues with being able to place it, to push it around on site, that type of thing.

Another benefit which really relates to the overall quality of the concrete. So workability I believe, is very important to getting a high quality concrete. And along with that, being able to retain that moisture in the concrete helps with that drying shrinkage reduction. So if you're holding that moisture in the concrete so that it can hydrate that cement, it's not, you know, evaporating out into the atmosphere.

So, yes, essentially a two-fold benefit. You're getting an easier concrete to place, which results in a higher quality job, and then you're getting less cracking and things like that on site. So your result from month one, in front of the client, is much better than it is without, you know, addressing these challenges. Is that fair, Hayden?

HAYDEN:

Yes, that’s good. And probably just to add on there, even the ability to close-finish, to get a good surface, has been recognized. And in all aspects, even shotcrete where, you know, traditionally that’s sometimes been a challenge. So that's good. But there’s definitely some benefits. And we want to make sure that the site teams are getting - first, trained, on what's going to come through the pipe, and then that they’re getting the best result. Because, like Doug said, that's 100% the start or the key of long term durability, which probably rolls into our next slide, Brendan.

And really now looking at what does the asset owner themselves get out of all this? That's the key part. You see some roading authorities or governing bodies or whatever it is, construction companies or ready-mix companies, they’re setting the guidelines, the outline brief, so to speak. And our job is to help make concrete the best it can be to hit those milestones that they’ve put out. For an asset owner, long-term durability is huge. Obviously no one wants to spend months and dollars on repairs, repair cycles etc, so there should not be any reduction of quality and durability while we're chasing sustainability.

And that's probably… if you dive back at a couple of our recent webinars and material, you'll see that message coming through. But that's really our focus: how to extend life of concrete without going away from this drive to get more sustainable. So that's a big one, is how to get these goals and ensure we're getting the right concrete, right result.

And then protection from within is really where it starts. If we're getting the right quality concrete, that's the long-term protection from day one. If you’re densifying, you're really making the matrix of the concrete the best it can be. Not only that, but the surface as well. You know, when you're talking about abrasion resistance etc, you really want to think about the long term.

And that's probably our biggest focus area for the asset owner, is making sure they get the carbon reduction they’re after, but they get the quality they’re after, as far as durability. Trust that helps. Keen for any questions. We've been talking a lot. We'll get to question time very soon. Back to you, Doug.

DOUG:

No, that's good. And I 100% agree. We've got to make sure that that doesn't suffer - that long-term durability, you know, if we want a win-win situation here. So as far as looking at areas... Again, some of the feedback on the last webinar was to look at case studies and, you know, actual projects and things like that.

A lot of this area with carbon reduction is fairly, I guess, new. And we're dealing with commercially sensitive clients and projects and that type of thing. So we can't share actual examples of projects, but we can give you examples of the types of projects we work on. And we would strongly encourage you to come and discuss... or come and have a discussion with us around how we can benefit these low-carbon... whether that's low carbon mixes, whether that's from an asset owner point of view, how to implement them into your projects, that type of thing. Or whether that's from a ready-mix, or whether that's from a concrete placer, you know, working out how we get this concrete down on the ground, and supporting our structures.

So firstly, the marine and coastal is an area we've done a lot of work in, in terms of extending service life. So working against steel corrosion predominantly from chloride attack on the concrete. The roading and highways area. So getting that long term durability, particularly around carbonation in roading, is the big topic. And, you know, while it's a slow attack, it does does break down that concrete microstructure and eventually attack the steel. And you know, you can do that from day one with admixtures, protect that concrete from those sorts of attacks. Mining construction. The emphasis there really is on protection against the processing chemicals there. The acids, hypersaline water, high mineral water. It all leaches the good stuff out of concrete; and being able to protect that from happening, make it last longer, along with the ease of placing. So often you've got concrete pours happening underground, which could be, you know, 1 to 2 hours open time for the concrete and being able to have an admixture that increases the durability but also doesn't create any problems around set times and strength gain, all those type of things. We've seen some big successes there. Placement of shotcrete and sprayed concrete. We touched on it earlier, but being able to reduce those pump pressures; being able to finish it off easier; less bounce back; less concrete coming off the walls – “rebound” is the word I'm looking for - from the walls when you're spraying shotcrete. Again, similar sort of idea, but piling is where you're wanting to keep the mix cohesive and workable. Keep it together. So with a piling mix, you often get issues with groundwater, and bleedwater from the mix, segregating the concrete; and being able to resist those and keep it together is, very important. Ultra flat floors. So, you know, increasing that abrasion resistance, making sure we're not losing any of that surface durability, is an area we can help with. And lastly, it's more your area Hayden, but top deck waterproofing. Do you want to ...?

HAYDEN:

Yes, yes, that's interesting. There's a lot of waterproofing products out there. But it's one thing that’s probably gained a lot of traction; and be interesting to see if anyone is involved with this on the call. It's where it's traditionally been membranes, coatings, type approach to these, top deck waterproofing - the ability to go integral and waterproof the concrete itself is providing some really good results. So that's another benefit of doing this system. Something that can't be reversed, something this can't wear etc. So yes, that's some of the areas we work in. I trust that’s helpful, to provoke some thoughts. I'm never a big fan of webinars being sales pitches as such so don't get us wrong there. We have had feedback to go into a little bit more detail about what these products do, so hence why we're diving into that space. But that's really getting us to the end now. That's plenty of our voices; we’re keen to hear your voice. In summary: obviously we’re colloidal silica fans. Everything we’re built off is really based on that technology. We've had such a big experience for that, and it's well recognized in the industry with some really good wins, as we’ve just been saying.

So a big focus around that with the liquid [admixture] - maximum benefit and minimize risk, because that’s huge. Risk is becoming more and more, you know... project teams are passing around risk really, they’re trading risk in construction. How do we minimize that but get the right result? And then, really looking to include or be early in discussion on projects, mix designs, new movements towards different binders, you know, cement replacements etc. How do we maximize what we're trying to do, get it to the best place, get it into the construction arena rightly and performing well.

So hopefully that summarises roughly what we went through. But yes, keen to hear any thoughts. And to that question, if we can just ask that now. Very interesting. If anyone wants to come forward, what is the number one challenge? If you had to write it in a line in concrete production or concrete construction. Be really interesting.

Throw some thoughts around. We’ll wait a minute as they come through.

And then any other question, anything we've touched on? We sort of ran through that at a high level. Anything through that that you're interested in. We'll also fire out a bit of a summary where you can come back with any questions on email that you're keen to chat through.

So I know everyone's got busy schedules.

BRENDAN:

We’d be glad of any general questions. Did you want to say a little bit more about the permanency, Hayden, of the admixtures, the benefits?

HAYDEN:

Yes. We probably never dived into exactly what colloidal silica is doing in the concrete. What we're really doing is growing more calcium-silica-hydrate. We’re hydrating the cement better. So we’re pore-blocking, to a point. But we're growing more C-S-H in the concrete and making it the best it can be.

Because of that, it's really that we're not able to reverse that. Once that's happening, once that’s set up in the concrete, you can't reverse that. So that's permanency of it really. So you've got advantages of colloidal silica products in production and construction. But then long-term, because of its ability to hold up and resist wear, resist contaminants, moisture migration. Basically if you take moisture out of the equation for most things in concrete, you're on a win as far as getting the best life out of it. So yes, I think we’ve got a couple of people with some questions. Half a second.

BRENDAN:

Very good.

HAYDEN:

Good to go - or are we going to wait here?

BRENDAN:

It’s all right, a couple of the guests are typing, so we’re looking for that to come in.

HAYDEN:

Fine.

Any other points we should chatted about, Doug? Actually one thing I'd be interested to ask, what is a webinar topic that you guys would like to see? We roll these out monthly. If there's any... either email or on the chat now would be helpful too. But when we email out for feedback, we’d be really keen - So can you hone in on this topic? We’d like to have a discussion about this topic. That would be really good - anything concrete related.

DOUG:

No, I think you've covered it well. I guess the other area as a company - one of our big values is “evolving”. So when we're working with these mixes, we definitely want to be part of a journey. We're not trying to just say, here's a product that will fix all your problems. It’s more of, let's try these 2 or 3 products, see what works. Let's refine it. Let's get it to a point of, you know, a dose rate; a product, everything that works for everyone there. And that's something that's very much appreciated by clients, we get that feedback a lot.

BRENDAN:

We've got some feedback there from Loch, which is much appreciated, in regard to MARKHAM CNS [colloidal nanosilica] liquid products versus powdered waterproofing products. The MARKHAM product, Loch says, does produce a better concrete to mix and pump and place and finish.

HAYDEN:

Yes. We're not here to bag... you know, some of these products have been around for a long time, but concrete does change. Production does change. And that's probably our message really is, let's stay ahead of the curve. Making sure we’re getting the right system. So yes, I agree with saying that. There's some very good ways of getting to work with concrete, through different products. But can we get that consistency right from production through to finishing? I think that's a good comment. Thanks.

BRENDAN:

I suppose it’s one of the things we've seen in the industry, is that the changes have, I wouldn't say, taken people by surprise, exactly. But they've been, the newer mixes are perhaps more different than people were expecting them to be. And they need to be taken into account when you're training in places.

HAYDEN:

Yes, agree. Do you want to wrap us up, Brendo?

BRENDAN:

Yes, I think we can probably wrap up there, if there’s no more thoughts. Thank you, everybody. We will of course send you a follow up email with contact details and a survey link. You can tell us what you would like to see that we could improve. And yes, as Hayden said, we would be really keen to know any particular topics that you'd like to talk about or particular challenges. It's always fodder for these sessions. We love it.

HAYDEN:

Good. Thank you.

BRENDAN:

So thanks for joining.

DOUG:

Thank you very much.

HAYDEN:

Cheers!

BRENDAN:

Thank you.