EP #160: Is Type IL Cement the Problem, or Did It Just Expose One?

Seth (00:00)
And welcome to another episode of the Concrete Logic Podcast. And today I have Concrete Bob Higgins back on the show. And today, this is what we're going to talk about. Type 1-2 cement is making a comeback. It's because the market's asking for it. The contractors, producers, and owners want concrete to act like concrete again. But let's not pretend Type 1-L caused every problem.

concrete had issues before PLC showed up. We had scaling, dusting, cracking, bad curing, too much waters, and still had the specs that cared more about 28-day strength than long-term performance. So going back to type 1-2, it might help us out, but it won't fix the bad concrete habits that we had before. So the real question today is, if type 1-2 does come back, did we actually learn anything? So Bob's going to help us out with that today.

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questions or share the things that you're going through and It's like a community that we can talk about our concrete problems or successes So check it out concrete logic Academy comm or concrete school dot co All right, Bob Let's talk about There's there's there's rumors out there that some folks are going back to type 1 to submit some manufacturers have turned off the

I guess the type 1L spigot and are now going back to type 1-2. So I wanted to bring you on because I think we need to refresh everyone's memory for the folks that did switch to type 1L. Before type 1L came out, we still had problems, right? When we were using type 1-2, we still had the same issues that you do still see today. I just think type 1L kind of

exposed bad practices more because it's so sensitive, right? It had less clinker in it and I guess a less, a way for bad habits to be covered up. So now if we could revisit the things that were going on before type 1L, I think we can help prevent maybe a bad switch back, switch back.

Bob Higgins (04:24)
I'll tell you what, hallelujah. Absolutely. I just read an article yesterday on this very subject where they were talking about how this is actually teaching them a lesson because when the Type 1L first came out, they were seeing it was one for one with Type 1-2. I said, no, no.

It's not. There's different properties to this. And what makes it kind of worse is if you look at virtually all the ASTM standards that are on concrete, the ASTM standards are on concrete that we don't place anymore.

So what are we qualifying? mean, everybody is out there is so confused. And like you said, there's a history that we have to revisit to where we don't keep repeating these mistakes because that switch to type 1L was a very bad idea. But it was based on

mounting problems that they were having with type 1-2. And that kind of brings us to some historical issues where we've gone along and with very little fanfare made changes in the concrete, the chemistry, the semantics, and everything else, not dealt with them and not expressed what the changes could possibly do to somebody who's in the field. So.

I really don't like how the concrete contractors have been thrown under the bus. Because if you take the original standards and the original cement formulations, what the concrete contractors do is actually pretty solid. But what they're basing it on doesn't exist anymore. So it's...

It reminds me that there's a hole in the bucket, dear Liza, where you keep seeing all these things you have to do. if you can't carry the water because there's a hole in the bucket, you have nowhere to start. it'd be really because that's what I wanted to do is kind of have a conversation with you today where we just talk about the genesis of this, which really began in the 1920s. In the 1920s, cement was much, much coarser.

was really, really durable. So people are excited about it because Portland cement was very durable and they were replacing concrete. And even in the 50s, there was little to no deterioration. But the problem was, is as it became more accepted, what happened is there were demands on the time element because the set and cure of this type of concrete was very, very slow.

Say that they want to accelerate it. So somehow, someway, somebody decided that compressive value was the best way to evaluate the concrete. So as they plug this in, they found.

look, if we grind the cement finer, we can get higher strengths much earlier. So as they started doing that, they started having issues because the three-day curing wasn't controlling the cracking and the warping and the curling anymore. So they had to switch.

to seven days and they made it sound like that's the way they've always done it and that's not true. Because as I kept digging through the archives that I could find, concrete required very little water cure when it first came out in the 1920s. And as they kept getting the grinding finer and finer, it demanded more water because there was more heat generation and the cement formation was much faster. So the other thing they did is they found, well, if we

reduce the amount of cement in it, we're also going to reduce the amount of heat. And that was successful. And it was still meeting the compressive values that they were seeking. But unfortunately, down the line, as we've discovered,

There was this really good article in Concrete International by Evman Rome back in the 1980s where he discusses this and he showed that there was a 34 % reduction in cement content to hit the exact same.

PSI at 28 days. So if you could magically go back and compare 1980 concrete at 28 days with a 1920 or even 1950s concrete, the 1980s concrete was 500 % more permeable to water. But that was never the case.

Seth (08:50)
Yeah. So

did I hear you right? So back in the 1920s, we had coarser concrete. They didn't grind it up. And the reason they ended up grinding it up more was because they found that it sets up quicker. It meets the, not just the 28 day. We went to like a seven day. I mean, we're down to two day, three day strength requirements.

Bob Higgins (09:11)
Yeah.

Seth (09:13)
So that was the reason why it was, I guess, now it's finer. That was the evolution between the 1920s to what we have now.

Bob Higgins (09:25)
in

1980 and it kept progressing and they're still progressing, if you can call it that. So they go with a finer and finer grind because basically they can get more concrete with less cement. Now, unfortunately, type one was the concrete.

being used back, the cement being used in concrete back then. And then they're finding out that as they did the finer and finer grind, that they were starting to get the cracking and warping again. So dealing with that, and this is what puzzled me, and I've brought this analogy up several times. There's type one and there's type three cement. Type one and type three cement are chemically identical. The only difference is that type three is a very, very fine grind.

So as they keep grinding the type 1 finer, it starts becoming more and more like type 3. Well, you can't use type 3 in standard environments because the concrete heats up too much, it cracks too much. So what they've done with the type 1, they started adding type 2 to slow down the heat of hydration, but it also slows down the hydration process itself.

And the proportions were changing. The proportions, as they were changing, were not being conveyed to those working with the concrete. So the people placing the concrete would gain blame for problems. Well, concrete's always been concrete. Yeah, it has been concrete, but you didn't tell them about the changes.

Then they had these recovery requirements that came in later on as the environmental issues came in. And then they want to start adding these grinding aids to cement to make it more efficient so they're using less energy. have this cascade of negative elements being placed into the cement and the concrete that has not been conveyed to the people in the field.

Yeah, are the concrete contractors to blame for some of this? Yeah, to an extent. But if they were given the original material, this wouldn't be happening. So they need to get good information so they know what they're dealing with. You can always deal with a problem when you know what the problem is. But if you don't know what the problem is, it leads to all the speculation. I read these things about how water moves through concrete and all these other things.

Most of it is inaccurate because as I keep reading the studies, I can't find any data that says absolutely this is what it does. ⁓ You don't know absolutely. I've got over 3,000 studies and tests in my library and almost all of them have assumptions incorporated into their conclusions. My take on this, you cannot.

Seth (11:52)
Yeah.

Bob Higgins (12:07)
include an assumption, and then have a conclusion. If you have an assumption, there are open-ended elements that you have not dealt with. So your conclusion is based on a predetermined concept of what's going on with the concrete.

Seth (12:24)
No worries.

Bob Higgins (12:29)
That's the problem. It's been assumption after assumption after assumption. we have a real opportunity when we go back, like you were saying, back to type one, type two cement. But we need to deal with the reality of it. Otherwise, we're going to keep repeating the same mistakes over and over again. The curing process that we use is

I thought that what Dr. Zollinger did with the Texas Transportation Institute was really illuminating. He took 4,000 psi concrete in a lab test. So he did it without cure and a seven-day water cure. What really stuck out for me

was that the 7-day water cure, when they isolated the top inch of the concrete, it was a full 20 % lower in compressive value than the remainder of the concrete. Well, that will not show up in a compression strength test because it only registers the break, not the squash. So there's techniques that we use where some of the problems are hiding out in the open and we don't know it.

So we really need to revisit this. If they're going to go back to type 1, type 2, let's revisit this and go back to the basics. OK, what do we have? Is the type 1, 2 cement that we get from company A, B, C, and D, are they the same proportions? Do they have the same proportion of type 1 and type 2 cement? Do they have the same proportion of limestone filler? We need to know this.

The other thing that bothers me, the ready-mix producers must, by law, reveal whatever's added to the concrete that's outside of concrete. If it's a plasticizer or some other modifier, they are required by law to produce the data of what they're adding to the concrete. If it's not sand, aggregate, and cement, they have to produce this. That requirement is not given to the cement producers. Why?

I'm not getting any answers. even... I wouldn't hear it.

Seth (14:28)
I don't have an answer for you.

Well, I think we know that your first question was, the proportions the same from one manufacturer to the next? the answer is no. I I could sit here and tell you that now. So what do we need to do? So the curing, the example, you were saying the water curing.

Bob Higgins (14:48)
Yeah.

Seth (14:59)
didn't work in that case as far as having strength that was consistent throughout that thickness of concrete. So ⁓ what would you suggest that we do now that we're going to be working with a new cement? Well, some of us are going be working with a new cement. Well, new, but we're going to, it's new, but we're going back to the old, supposedly the old cement.

Bob Higgins (15:08)
Yeah.

We'll see. Yeah. Yeah.

The old news, Samantha, we're going to go back.

Seth (15:23)
the old news submit.

how do we need to approach that so we don't screw this up?

Bob Higgins (15:29)
My opinion is they need to find methods of self-curing, where they make the concrete autogenously curing itself, where you give it water reservoirs. And I've seen all kinds of studies where they're using these super absorbent polymers and all these other things. And some help, some don't. But there's been an accelerated study of this. So I know there's something going on in the back room.

Otherwise, there wouldn't be this interest and there wouldn't be all these studies coming out. They can qualify this by analyzing the results of the curing because one of the things that came out as they became a little more sophisticated with the testing they were doing in field concrete.

And I noticed this was global. There was a study in the Middle East and also in Portugal, along with the United States, where they put in these thermal couples as well as these embedded humidity devices. Well, completely unexpected. Even though they were water curing and putting curing compounds on, the concrete, the top inch of the concrete was self-desiccating within two to three weeks. Well, if they're putting water on it,

Why is it self-desiccating? It shouldn't self-desiccate if it's getting wet. ⁓

Seth (16:47)
what I'm going

to pause you so not everybody knows what self-desiccate means. So what does that mean?

Bob Higgins (16:52)
Okay, what happens is the water gets used up and the relative humidity drops. So what happens, the water gets captured, at least...

for a period of time by alkalinity. So as the cement initially forms, it reduces the amount of water available, but that also concentrates the alkalinity. As alkalinity concentrates, it lowers the relative humidity. Once it drops below 85%, the efficiency falls dramatically. It goes from about 100 % efficiency, 90 to 100 % efficiency, 85 to 90 % relative humidity.

and drops to about 10 % efficiency at 80%. And then once it goes below 80%, cement formation stops. So it self-desiccates. So the cement formation in the surface is not happening. It's not consistent. And that's the first line of defense for all concrete is for environmental protection. The surface should be the top priority. And it's not. It's allowing water to penetrate because now we don't have as much cement formation.

Everybody's yelling about, we need a lower water cement ratio. Well, if you're not producing cement, that's a negative return on investment. Why put in cement if it's not going to form? All you do is you're just creating more filler that's going to create moisture issues later on down the line. We really need to get back to the basics. I don't know how to do that.

Seth (18:10)
Yeah.

Yeah, so.

Bob Higgins (18:25)
unless people just want to listen and finally put their heads together and put a program together.

Seth (18:30)
Yeah, so the your your

you're killing the concrete before it reaches its full potential when it's self-desiccating. So the water is not getting to all the cement for the cement to do its thing, is what you're saying.

Bob Higgins (18:44)
trip.

Yeah, precast

concrete's a good example. And that is a good example that the concrete industry doesn't understand its own product. I'm going to come around and say it. Because precast is supposed to be the premier concrete. And the center portion of it is great. The outer portion sucks.

Because if you precast concrete and you compare it to standard concrete, if you have them both side by side, standard concrete, put some water on it, and it gradually absorbs. You throw water on precast, it disappears. Throw more on, it disappears. Throw more on, it disappears. Why? Because it heated it up. When they heat it up, that kills the solubility of the calcium hydroxide. It also kills the ability of cement formation because of the...

Seth (19:04)
Yeah.

Bob Higgins (19:31)
elevated temperature because they're showing all these studies, know, 50 years of studies. have a graphic that I use in my presentations when concrete is exposed to say 130 degrees Fahrenheit.

Seth (19:45)
You're a popular guy. You're good.

Bob Higgins (19:46)
Sorry.

Okay. When it's exposed to 130 degrees Fahrenheit, after one year, only reaches, and this is in favorable conditions, 73 % of its design strength at one year. So for convenience, we're sacrificing durability. We have to start waiting.

the durability factor with convenience.

Seth (20:14)
Yeah, mean,

everything's got a trade-off. There's not a perfect concrete out there, right? You're going to give up something to achieve something else. the precast example is they do that for modular construction. So they prefab and do that. So when you do that, you're giving up the durability, what you would get out of a cast-in-place version of that. But they

Bob Higgins (20:28)
Yeah.

Seth (20:38)
you know, some owners out there, builders out there, appreciate precast because, you know, when it gets out there, it gets erected. So it's a quick construction process. So you're gaining that, but you're giving up some of this other stuff. So yeah, I mean, with everything, there's going to be a trade-off. There's nothing perfect out there.

Bob Higgins (20:48)
Exactly.

And the thing is,

yeah, now the thing is you can add these materials that can compromise, but then there's other materials you can add that will add value to it. For example, there's additives you can put in precast concrete that will stop the calcium hydroxide from becoming insoluble when the temperatures increase. That will help.

Seth (21:23)
Yeah.

Bob Higgins (21:24)
develop more SNAP. Now they're not doing that because they're not really interested because there's been no demand for them to change anything. So if the demand comes from the field, look, we know you can do this so this is what we want because it's not really expensive to do it. I mean, there's almost no added cost versus the added value. I mean, the added value is by far a bigger issue than the costs are.

Seth (21:50)
Yeah. So let's get back to our prevention suggestions on the switchback. So the first thing I heard was, first of all, we got to know what we're dealing with. we got to ask as contractors and producers, what are we dealing with as far as the submit?

Bob Higgins (21:57)
Yeah.

Yeah, exactly. I looked at these two bags of cement when I went out to Colorado. It literally said type one two or type one L or.

Seth (22:06)
⁓ Because,

Yeah.

Well, they didn't want to print new bags, they... You got to circle one or the other before you ship it out. So that way... Yeah.

Bob Higgins (22:23)
yeah, so if you're apples, you might get oranges.

my god, I mean, I couldn't believe what I saw. And we didn't know it was in the back.

Seth (22:33)
No? Is that not what happened?

Yeah. Yeah, that's not good. Yeah, so you got to know what you're dealing with, because then that's going to determine your methods. Because I've seen it on drawings before, where a structural engineer said, in the spec, all these specs now, this gives you an option to use type 1.2 or type 1.L. You know, C150 or C1595, is that right?

Bob Higgins (22:40)
No.

Yeah.

Seth (23:03)
Is that right? OK.

So that gives you the option. But what I saw on this one engineer did on the actual drawings he wrote is, if you are going to use type 1L, you have to do these things. So you have to submit one of your submittals, your curing process, basically. How are you going to prevent type 1L from doing what?

has happened out there in the field when it doesn't get properly cured or handled or it's not what we're told it is when it gets out to the job site. I've heard instances where the amount of limestone is not consistent across a job, which is crazy. We were talking about consistency.

So if you don't have consistency in material, can't ask the contractor to change his methods with every stinking truck that shows up on the job site. It's all got to be fairly consistent across the board if you want a good product.

Bob Higgins (24:07)
And I experimented with the type 1L because I wanted to find out how much float I would get with the the limestone and it was ridiculous. I mixed it really well and the best way to determine that was to take a neat mortar with the type 1L. I did with aggregate and it was less obvious so I did it with a neat mortar and there was literally a layer about 64th of an inch of just pure limestone dust.

It all floated

Seth (24:37)
So how did you do that?

So what did you do? You just took the cement by itself, didn't mix it with aggregate or sand, and you did... ⁓

Bob Higgins (24:45)
He had to sit with water and

let it sit in this bucket. And I went ahead and cured it the way it's supposed to be cured. And I had about a 64th of an inch of limestone dust that collected at the surface. It wasn't obvious when I put aggregate in, because the aggregate will kind of block some of the.

Seth (24:58)
Yeah.

Bob Higgins (25:05)
migration of the limestone, but I wanted to find out just how light the limestone was and how it would stratify. And it does. It does tend to stratify, which is really, really bad news. And I saw this one job where we asked them to take cores and the cores fell apart.

I've never seen that with type 1-2 cement.

Seth (25:28)
Yeah.

Bob Higgins (25:29)
So I mean, that alone just shows the quality difference. And again, like you said, if we're gonna go back there, let's fix the problems that led us to this in the first place.

Seth (25:41)
Yeah, because the guys aren't going to have excuse anymore. Can't say, hey, that's the material. We got what we asked for, right? Type one, two.

Bob Higgins (25:45)
Yeah.

Yeah, and I will take the blame and the credit for causing a lot of this to happen because I put out a question that people started asking because a lot of the contractors I was talking to were told that their problems were regional and isolated. So I kept talking to these different contractors throughout the United States and they all had similar

issues. So I presented a rhetorical question, said, how is it that all these concrete contractors have been in business for decades have suddenly become incompetent overnight?

And they started comparing notes. as people started talking, hey, wait a minute, this is not isolated. Because there's the adage of divide and conquer, and that's what was happening. It was a divide and conquer. But now that people are talking to each other and realizing we need to go back to this, let's do it the right way then. If you're going to go back to this, let's get this together and get people educated. Because if we can get them educated,

and what they need to do and the changes they need to make, we're going to get some really good concrete. Really good concrete.

Seth (27:02)
Yeah.

Cool. I think that's a good spot. Yeah. Yeah. No, that's a great. I think we'll pause that today. I'd like to bring you back on and talk about what we talked about before we hit record and talk about how we're mishandling our admixtures. We're not doing ourselves any favor if you don't mind coming back and talking about that.

Bob Higgins (27:05)
This, yeah, this is not, let's not waste it.

Yeah.

⁓

no, not at all, because that's one of the ambushes a lot of people are getting. So everyone's confused about what's causing the problems. that's OK. OK.

Seth (27:35)
Yeah, don't give it away. We want people to come back.

All right, Bob. I appreciate you coming on the show. Everybody check out the show notes. I will have Bob's link in there so you can reach out. And if you got any chemistry issues with your concrete, this is the guy you want to talk to, Concrete Bob. So there'll be a link in there. There'll be links for the Academy. Make sure you check out the Academy. Bob, thanks for coming on the show today. Appreciate it.

Bob Higgins (28:03)
Thank you for having me.

I always enjoy this.

Seth (28:06)
Yes, folks, next

time, let's keep it concrete.