EP #132: Concrete Truth - What the 2024 PLC Report Admits That 2011 Didn’t

Seth Tandett (00:00)
And welcome to another episode of the Concrete Logic Podcast. And today I am running solo. Very similar to what I did in episode 126. So if you didn't listen that episode, you... Excuse me. I broke down the 2011 report on PLC.

It's the actually if you're on YouTube, I'm Sharing my screen here, but ⁓ It's this report here. It's the state of the art report on the use of limestone in cements at levels of up to 15 % and I went I went through that and Just really just went through and shared what that paper had to say It wasn't my opinion. I was just

you know, stating what the paper had. After that episode came out, I shared some clips like I do on ⁓ LinkedIn and the American Summit Association reached out and commented on the post saying, hey, did you know there's an updated version of that report? There's a 2024 version. And they were nice enough to share that with me. I, I,

Actually, I did know there was a 2024 report and I believe I mentioned that in the episode 126 when I looked at the 2011 report, which by the way was updated in 2014. So this is probably way confusing. But anyways, so I knew it was there. The reason why I went back and looked at the 2011 report was because it was...

It was actually cited in this new report, which is this one here I'm showing on my screen, 2024 report. So I thought it was good to go back and look at that report to find out the, I guess, an origin of why.

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It was important because I wanted to know the basis of the newer report.

So anyhow, so here we are, the American Submit Association, formerly known as Portland Submit Association, shared the 2024 report and I told them I would review it, read it, and here we are. That's where we are today. let's get started here. ⁓ Just before I go into the,

I guess what details are in there. Just a couple things that stood out to me. First is the 2024 version. We got a couple more authors involved here that were on the 2011 report. And then my favorite thing.

Here I'm scrolling, scrolling, scrolling, sorry. This is my favorite thing in this whole report. But if you scroll to the...

fifth page of the 101 pages of the report. There's graph here that shows the blended cement share of total U.S. cement consumption. we were well less than 10 % of the cement used in the U.S. was a blended cement all the way up to we could say according to the graph here.

about January, February of 22. And then it just shoots up at skyrockets up to nearly 60%. And the graph ends in this report in November of 23. So we talk about the drastic change here. And this is the...

illustrates it quite well. ⁓ just an update, I saw American Cement Association commented or posted saying that it's now, the blended cement use is now up to 65 % of US consumption. So it's still increasing.

So that's quite a bit of a difference in a very short amount of time. We're talking about less than four years. So that's why it's such a...

Popular topic, not just in this podcast, but across our industry, because it's definitely changed things up. like I said, if you listen to our episodes, we've talked about folks that are successful and ones that aren't successful with the new cement. we're trying to highlight why that is.

But anyways, in this episode, we want to get into it here is the differences between the two reports. So we have.

Well, roughly 2011, again, the 2011 version was updated in 2014. This new version is...

2024 so you could say about decade of a. Experience here. Added to this report.

this newer report.

So let's compare the two and see what the differences are. here, this is the, I guess this is what spurred this episode here is a comment from American Cement Association posting that, thank you for taking a look at the 2011 report. Just want to let you know there's a 2024 report.

And that's why we're here today. So why is this report important? These reports, and I've shared with you, there's a ton of these things. I don't know how many of you all out there actually look. But any kind of paper, research paper, white paper, article, or anything on PLC or blended cements,

there's references there that are listed and this report, the state of the art report is referenced quite a bit and that's what caught my eye. basically, know, just got curious, wanted to know why this report was referenced, what's in this report and why is it so important. So, you know, it's basically one of the backbones of

the whole PLC adoption in the US. So like I said, it's the...

2011 report we talked about we've updated that So what's what's changed since the 2011 report let's just get into it

All right, so back in 2011-2014 report, one of the quotes in there was, no significant risks to durability are expected from the use of up to 15 % limestone and cement. Now, when you go into the 2024 report, it says, PLC mixtures may show higher carbonation rates and chloride ingress, but these effects can be managed with proper curing and assay.

SCM use. So that's quite a bit difference there.

Let's talk about admixtures in the 2011 report. says PLC concretes can be considered essentially interchangeable with ordinary Portland cements and admixture performance. And in the 2024 report, it says some projects have reported difficulty maintaining consistent air entrainment, particularly when SCMs are also used. Careful admixture control is necessary. So again.

Things have changed quite a bit from the first report to this updated one.

On evidence base, basically the, where did the 2011 report get most of its data from? So in the 2011 report it said laboratory and limited field studies are sufficient to confirm that PLC performs similarly to type 1-2 submits.

And then if you go to fast forward to the 2024 report, it says with 10 more years of field data, PLC can now be confirmed as reliable across a wider range of conditions. So.

That's where we got in 10 years.

And finally the rationale of using PLC in 2011 was framed this way. The main benefit of increased limestone is improved efficiency and milling and resource utilization with secondary CO2 benefits.

But in 2024, it says PLC is a key solution to reduce carbon emissions and address climate change in the cement sector. So CO2 was secondary in the 2011 report. In the 2024 report, it's now...

primary.

All right, so you with me so far?

All right, we cut through all that.

Just a quick refresher on the 2011 report in case you didn't catch episode 126. The 2011 report was all about reassurance. It was heavy on lab studies. There were, believe it not, 230 references, know, other books and papers to reference to.

but it was limited on the field data. We beat this horse a bunch, but the message was the cement, the same cement you've always used just with a little more limestone. There's not a whole lot of risk, no problems. Things should go well.

And yeah, so now if we look at the 2024 report.

It's got a lot more to it. For one, there's 493 references in the report. That's quite a bit. It does have more case studies in it. So there's some bridges, pavements, and even some long-term exposure sites, which we'll talk about here a little bit later.

Definitely has the 2024 report has a different tone. Here's a quote from the report. PLC is a key solution to reduce carbon emissions and address climate change in the cement sector. So again, hitting on what our priority is here.

But there definitely was a shift into emitting. There are issues. There's ⁓ again carbonation, chloride ingress, admixture sensitivity. All those things were brought up in the 2024 report. But again, it says these things are controllable or manageable.

Which is fine. So, you know, more time, more data. I mean, that's how science works, right? You get more data, you can update your...

your findings.

Let's talk about the positives beyond CO2 and it not necessarily has to be positives for the concrete contractor or the producer. So, it's one of the lines in the 2024 report again citing less clinker production results in lower energy demand during finished grinding, which means real energy savings at the mill, right?

Also in the report it says in some cases PLC concretes exhibited improved workability compared to OPC, Portland cement. And what else here? ⁓ the lower heat of hydration of PLC can be beneficial in mass concrete applications. So they're finding that in mass concrete

that PLC is a possibly a.

It's a good use case for PLC, which makes sense, right? It's reducing the clinker, reducing the heat. So, I guess the point is there are pauses outside the climate argument. Producers save some money. Supposedly you get better slump. And in the use case of masks,

concrete it could help with thermal cracking. So those are things worth pointing out I believe.

We kind of hit on these.

here. We'll go ahead and jump to these. So there again you got to kind of pay attention to what they're saying. Obviously this paper is written to promote the use of PLC but they do like in the 2011 report do caution you. So PLC one of the things cited here PLC concretes showed higher carbonation depths than

OPC and several studies. It also notes PLC mixes without SEM showed increased chloride permeability in some cases. And also PLC mixtures exposed to de-icing salt showed greater surface scaling if curing was inadequate. And we've talked about how important curing is and how I think it was two or three episodes ago we talked about

you know, how sensitive PLC mixtures are. So the curing is just that much more important. Also in the 2024 report, regarding air mixtures, says, entrainment performance may vary and requires adjustment.

Now, this is not saying these are failures, the message is always we can manage this new cement with proper curing, SCM blends, and with our water cement ratios. And then like I said, that means the PLC is less forgiving, it's more sensitive. When we were using type 1-2 and

some of us are still using it out there. You can get away with more, I guess, sloppier methods, right? With PLC, your margin of error is very small.

All right. won't like I mentioned before, there's some projects cited in here. So these are, like I said in the 2011 report, it was more lab studies than anything. But in 2024 report, have projects cited. There's bridges, pavements, exposure sites. So let's talk about some of these examples.

The first one is the PCA Southeast Exposure Site. That's, I believe, the longest project reference. It says concrete prisms were exposed for over 15 years. The report says PLC concretes exposed at the PCA Southeast Exposure Site performed comparably to Portland's cement mixes with respect to strength development and scaling.

when properly cured. So that's a positive, but these are just test blocks, not highways or bridge decks that are, you know, seeing thousands of cars running across them every day. So just... ⁓

⁓ But then here's another one. ⁓ The Utah DOT bridge decks, the report notes that PLC mixes have been in service for about 10 years in bridge construction with good performance so far. That's encouraging, but again, 10 years isn't 50 years or some of these things are built for 100 years.

Next one, ⁓ the Texas pavements. The report says PLC mixtures have been successfully used in pavement applications for over a decade with no documented durability related failures to date. Another solid example, but no documented failures doesn't mean there were no problems. It just means nobody's pointed any out.

The had some examples in here as well. The PLC used on bridge structures for about eight years in this example with chloride exposure data being tracked.

Then there's some several European projects, buildings and pavements. I think they're that ranged in between five to ten years in service.

So the 2024 report does have, you know, it has better examples. It's not just based on lab, you know, results. But we're still, you know, far from seeing how this blended submit performs over a long period of time. I mean, in the scheme of things, when we build things, 15 years isn't really that long.

So we got some time to experience these and see how these mixes perform.

So where does this leave us? Again, I'm just sharing with you all what's in this report. don't know how many of us are actually opening these things up. Again, this thing's 100 pages long.

you know, beyond maybe some academics out there that actually look at these things, but...

It's a we're definitely in the report. We're not talking about concrete falling apart. I would feel a little bit better if they actually actually pointed out some issues. I mean, they they do talk about them, but like in the project examples, if they said, hey, this was, you know, this was the issue and this is how it was repaired afterwards.

dealt with afterwards I guess. I think just based on reading the report I that must have occurred because they tell you ways to mitigate some of the issues that we we mentioned.

So, but what's an improvement is definitely over the 2011 report, 2011 update in 2014, is that they're actually admitting that there's issues. So we just have to manage the carbonation, the chlorides, with, you know, proper curing and...

managing our admixtures. But I pose this question to somebody this week on LinkedIn. I guess the way to look at this is if the CO2, reducing our global warming potential or reducing the CO2 in body carbon, would we still call

the PLC a success or an innovation? Or would it just be something that's sitting on the shelf still?

That's what I would ask of you all. but anyways, I appreciate you tuning in again. If you haven't, go back and check out episode 126, where we broke down the original report. And I appreciate the American Cement Association for reaching out. It's still ⁓ weird to call them Americans.

Submit Association, Stuffed Portland Submit Association, whatever. But yeah, so if anyone's listening and they want to come on the show and talk about this more, I'd be happy to have you on.

Want to hear more of these? Let me know. And until next time, let's keep it concrete.