EP #092: Concrete Contractors Unite: PLC Troubleshooting

Seth (00:01.101)
Welcome to another episode of the Concrete Logic Podcast. And today I have Mike Hernandez, the technical director of the American Society of Concrete Contractors, ASCC with me. And we're going to talk about a survey they did jointly with ACI about PLC, Portland, limestone, cement, or one of our favorite topics on this show. We beat the crud out of that thing and it still needs to be beaten on.

Mike's going to help us with that today. Before we get started, as I always do every episode, this podcast is the purpose of this podcast is for you all, the folks that are listening, but you can support the show in three different ways. The first way is share the podcast with someone you know. If you're listening to this, you know, someone that probably doesn't listen to the podcast and would

would get some kind of value out of it. So please share it with them. The second thing you could do is if you go to the website, concrete logic, podcast .com and there, you can, reach out to me a couple of ways. there's a contact button on there. And then then the bottom right -hand corner of the homepage, there's a little microphone thing. So you can either click the contact button that'll shoot me an email or you can click on the microphone and record like a voicemail.

And I'll shoot a voicemail to my email. And what I'm looking for you to do there is to give me topic or guest ideas, because I really want to put out episodes that you all want to hear. so the, I mean, I majority of the folks, I would say between 90 to 95 % of the people that are on this podcast is because someone suggested them, or re you know, referred them to come on the show. So that it's, it's,

Mike Hernandez (01:51.028)
for the next class.

Seth (01:57.613)
Up to you all to reach out and tell me who you want to hear or what topic you want to hear about. And then the last way is on the same, homepage on concrete logic podcast .com. There's a donation button at the top right hand corner and you click on that and then you can pick, you get, there's a couple of choices there. You can either pick any amount that you want to, donate to the show.

or there's another one where you can do like a subscription, a monthly subscription. I think it's set at like 10 bucks a month or something like that. But either one, if you feel like you want to give some value back in that way, you're more than welcome. And when you do that, what I do is the next episode after you donate to the show, I'll list you as a producer. So you'll be attached to that episode forever. Okay.

so feel free to do that. And also helps me when you, when you do that, you do any of these three things, then I know you're listening and that I am, you know, provide new value. Cause that's my goal. I want to provide you value on the podcast. So with that, let's get into it. Mike, Mike, did you, you want to tell us a little bit more about ASCC and what y 'all do for concrete contractors?

Mike Hernandez (03:16.884)
Thank you.

Mike Hernandez (03:23.22)
Sure. Seth, thanks for having me on today. For those who don't know, ASCC is a paid association for concrete contractors, about 700 members, about 600 of which are concrete contractors. And there's about 100 members who are either vendors who sell materials or ready to mix producers or engineers or consultants.

They can be other associations also. So we're closely affiliated with a lot of the major national groups like ACI, NRMCA, PCA, pumping, tilt up guys. So there's a lot of industry overlap within the concrete world. So kind of keep an eye on what each other are doing. And ASCC is very engaged at ACI to try and

influence on behalf of concrete contractors, the direction of the documents to make them more contractor friendly. So I'm actually personally involved on 15 ACI committees and our members are involved in over 50 committees to just kind of keep an eye on things and have an influence. So what I want to talk about you today is that as you mentioned, PLC is a very hot topic. It has come up

multiple times, World of Concrete, at ASCC meetings, at ACI International, like the San Francisco Convention, in the spring of 23, and the Boston Convention in the fall of 23. And by early 24, our members were clamoring for, what are we doing about this? What is ASCC going to do? And ACI 302 is the committee.

that works on slabs and because that group was seeing the biggest challenges, in general, if you're pouring walls or if you're pouring foundations, the effect seemed to have been minimal or none at all. Maybe it takes a little longer to get strength. Maybe it doesn't matter much. But for hard trialed slabs,

Mike Hernandez (05:53.172)
Those are the guys who are seeing the biggest difference from a 1 -2 to a 1 -L. And about half of respondents were saying that they were seeing no issues at all. So the guys who were having issues were asking, what are the other people who aren't having any problems at all doing differently than I'm doing? It becomes like, what am I doing wrong? What's different about?

about my mix or my team. So I guess that's was the genesis of, okay, what, what are we going to try and.

What can we do to determine what is different? And so I'm not sure how many people regularly subscribe to concrete international, but there was a article published in the February issue of CI, which went into the survey and it went into plastic and hardened properties that were different based upon what the respondents had said.

from a 1 -2 or a 2 -5 depending on where you're from mix. So we went to the New Orleans Convention proposing that we do a major mix collection effort from across the country, all eight NRMCA regions and say, okay, the industry was stable pre -COVID, we'll use those mixes as a baseline.

And then we want to collect a thousand mixes, 50 of a 1, 2 and 75 of a 1L from each of the eight NRMCA regions and then run them through an AI. And for the ones that contractors are saying are working well, try and find strong correlations and weak correlations for what has changed from that 1, 2 mix to the 1L mix to say, okay,

Mike Hernandez (08:03.892)
If I was doing great with my 1 -2 mix and I'm doing great with my 1L mix, what am I most likely to have seen change from that previous to the new one? To just give some direction for contractors, because if you just say, I don't like it, that's not much direction to your ready mix producer. You want to give them that.

Seth (08:28.013)
Right.

yeah, I mean to jump in here, so can we talk a little bit about the, or maybe you were getting to this was the data you collected. as, as most folks know that listen to this in concrete, contractors know this, that, you know, concrete is very, it's a local product, right? It's, it's made with local products. Did you.

Mike Hernandez (08:31.188)
I'm sorry, good and different.

Seth (08:57.645)
I was flipping through the information you sent me on the mix collection data. Did the NRMCA regions, is that what, did you all segment the data that way? Or I guess, can you talk about a little bit about that? Cause someone in, I'm in Virginia, you're in California. We deal with two different, totally different materials, right?

Mike Hernandez (09:25.364)
Yes, correct. So I'm actually, Jim's in California. I'm in the Denver area, in the Rocky Mountain region. And our headquarters in St. Louis. So you're absolutely correct in that we're dealing with a local material, but the NRMCA does make regional distinctions. So by

Seth (09:30.189)
okay. You're a little bit closer. Well, you're definitely.

Mike Hernandez (09:53.748)
We're trying to collect the data by region, just trying to subdivide it a little more, because maybe like.

the cement will be a little more regional than local. For example, there's a couple of cement producers in Colorado that basically service states a little bit to the east, a little bit to the south and west of them. And we're just in the process. So the funding approval was given and the committee approval was given in late March.

So by April, I was basically generating a list of ASC members and ACI 302 members of who would be appropriate to ask for this. So the ask kind of went out in late or early May and then kind of a refresh, okay, I don't have enough data yet. Ask more people in late June and where I really need support from your listeners is in...

NRMCA regions three and four, which is North Central and the Pacific Northwest, super underrepresented in Nebraska, the Dakotas, Minnesota, Iowa, Montana, Idaho, Washington, and Oregon. That there's just for whatever reason, not very many AESCC members and not very many ACI participating contractors to ask even.

and even fewer responding because the ones that have responded have said, we're not using 1L in Oregon very much or we're not using it in my, where I am in Montana, at least for whatever reason. It's about 50, somewhere between 55 and 60 % of the cement being used that was a 1, 2 is now being used as a 1L, but it needed help there.

Seth (11:49.901)
Okay. So, so I might've, I might've jumped ahead and I apologize, Mike. So the, the survey results that you sent me back was just asking who's, what kind of problems are you seeing right now that, that you have results from, right? So that you, you have the results from that. And then the next step is what you're asking for folks to participate in is where you're collecting data from these different regions.

of the mixes that you're having problems with. Is that what you're looking for? Are you looking for data for both, which ones you're having success with and ones that you're having problems with.

Mike Hernandez (12:30.58)
Well, I'm hoping to get more that we're having success with, but really I'll take anything at this point. If you're having problems, I will send a survey to them that says, okay, what are you seeing with this mix? Some of them are saying, okay, it's plastic property challenges, like it's a little water -starved or it's...

Seth (12:38.669)
Okay.

Mike Hernandez (13:01.14)
set times are all over the place or having hardened challenges like it's getting low strains of 28 days or it's cracking before I can saw cut it. I mean those but what I'm really hoping to get more of is ones that are doing well and then try and see what those mixes what is what is unique about those mixes as opposed to the ones that are not doing as well.

and use the AI to kind of crunch through those to get the correlations of what makes them special. Because it's a very messy problem. Because like you said, they're unique materials. You're dealing with different proportioning, different targets for how much cement, the aerogradations, whether they're kind of gap graded, that there's no intermediate aerogates.

manufactured versus natural sands, how much admixtures, what the water cement ratio is. There's so many variables. It's very difficult for a human to look at hundreds of mixes and distinguish what's important and what's not important. But the AI platform that we're working with should be fine doing those kind of things.

Seth (14:30.349)
So what are other than the mix design, are you looking for...

Mike Hernandez (14:38.58)
We'll give them a survey for performance feedback. That's why we'll talk to contractors, not just producers.

Seth (14:44.109)
Right. But when you're talking to contractors, I know we're focusing on the material, but you're also looking for, you know, how did they cure it? Thicknesses of slabs. I assume we're focusing on slabs because you said that's where most of the problems are. So you need to know probably thickness of slabs as well. I would think.

Mike Hernandez (15:09.332)
I'm not asking about thickness. I am asking them for the weather conditions that they placed it with, if they can give it to me. That would, which will kind of give some indication of the evaporation rate that they were dealing with. Like if it's, so traditionally 0 .2 pounds per square foot per hour is like when you start worrying about, do I need to get evaporation reducers? Do I need to be misting the air? Like the hot weather concreting threshold.

That point two, people are talking about being down to like 0 .1 or 0 .05, like one quarter of the evaporation rate is now a concern that you have to start putting countermeasures on it or doing things to make sure that doesn't get away from you. And at first we were recommending just using more evaporation reducer. Now it's true finishing aids, which would be like a...

trying to endorse anything but like a colloidal silica would be something that you could actually finish into this lab as opposed to the monomolecular like old school con film that you were just supposed to

keep the moisture inside the slab because it seems to be more sensitive to moisture loss than a 1 -2 was. 1 -2 seemed to hold on to its own moisture better.

Seth (16:36.845)
Yeah, no, I think, from what I've heard and what I've, you know, you know, the stories I've heard, you know, and, and folks that have been on the podcast, it, it sounds like the, the cement is, is not as forgiving as type one too. And it, so if you're used to get away with something in the past, you're not getting away with it now.

At least that's what I believe is going on. so if you had crappy curing, measures before processes before this, this makes is not going to let you get away with it. And it's like, like you said, I think, I think the water, the other water, the, it seems like it's, it's the, the issue is around how much water is in the mix from what I.

can tell from this point, at least the data that's been shared with me. But like around here, I haven't heard of like in the middle Atlantic region and, and projects that, we're associated with. I haven't heard a lot of problems in our area, but if you go further south of us, then you start hearing stories of people having problems. So that's why I was asking about the different.

how you're separating the regions and stuff, because some areas are not having as many problems as others. And again, I like your idea of send us the successful mixes instead of everyone so focused on when things go bad.

Mike Hernandez (18:24.532)
Yeah. And I think you kind of nailed it when you said that one, two was more forgiving that you can get away with a lot of things that you probably shouldn't have been getting away with, like just minimal or half -hearted curing, initial curing, which now you don't get away with that half -hearted effort. You have to do it properly to get the proper performance.

And just getting the message to the finisher, so the guy with the tools that you got to do it the right way. And then as that cement is being transitioned into new markets, then recognizing that or recognizing that, hey, what used to in a cooler weather, now it's going to take more time to set up and just being prepared for that or.

in hot weather, it might actually set faster. Just to be, to have a.

If they're prepared for it, they can probably handle it. But if they're not prepared for it, if they're thinking it's going to be the same as it was five years ago, it's just not. It's just the way it is.

Seth (19:38.893)
Mm -hmm.

Seth (19:42.605)
Yeah, I was in.

what was someone shared with me, I won't say who it is, but a pre -casters share with me. You mentioned earlier that folks aren't having issues with, you know, the, I don't want to say mass concrete, cause that's the wrong term to use, but the larger elements. So your columns, your walls, foundations and such haven't been an issue. But I think it's because those things typically,

You got the formwork that sits on them longer. So it that's getting that initial curing like it needs. So if you leave the formwork on that's essentially you're, you're carrying the concrete the way you're supposed to. but the precaster share with me, he's like, they have to pull, they have to pull their slabs within 24 hours to keep their, their processes and, and their, their, I forgot what the, the thing's called, but yeah, it turned the bets. Thank you.

Mike Hernandez (20:44.948)
Sure, in their beds, yeah.

Seth (20:47.597)
Turn their beds quickly. He's like, we're just adding more, more cement reason, more cement than we were using before. And he's like, how green is that? Cause they don't have a choice. They got to have that strength come up, in a short amount of time. So they don't have the luxury of like the, the, you know, these one, one L, folks are telling us that, you know, now you gotta ask your, you gotta ask your.

Mike Hernandez (20:56.34)
Very.

Seth (21:15.821)
client, the GC, the owner say, Hey, we're using one L now. Are you good with us breaking at 56 days instead of 28 to get the strength that the design team wants? The precast guys don't have that luxury. They can't wait.

Mike Hernandez (21:32.244)
Yeah, yeah, I mean, then you start getting into like strength of the hands, the admixtures or what trying to change proportioning to try and tweak the mix a little bit. So it does present a whole new whole new world and.

I guess I'm not as much on the precast side, but I was at the precast conference in Denver in February, and they definitely brought up that they are sensitive to turning the beds every day that they get out there and whatever they're going to do to make that happen. Heat the forums, whatever is happening to make it work.

Seth (22:21.869)
Yeah. Can you talk a little bit more when you put, you brought, so the survey that initiated this, this second, I would, this next effort that y 'all are making, the survey that you sent out and you're, you're essentially asking what problems you're having. Can you talk a little bit about that survey? What the results of it and what spurred this, this additional effort?

Mike Hernandez (22:49.78)
Sure. So it was a survey that was set up by the ASCC and ACI 302 committee. There was 173 respondents. There had already been a couple of surveys. There had already been one by ASCC that was sent out in the fall of 22. There was one set up by the Tennessee Concrete Association.

In the summer of 23, the NRMCA also had one kind of right on the heels of that in 23. So this one kind of opened in the late summer of 23 and closed in October of 23. And it was actually one of the better responded to surveys that ACI had done. And it had a good cross section of respondents from ReadyMix Cement.

admixtures, country contractors. I think the biggest actual group was ready mix producers. And one of the most striking things was that almost 80 % of respondents said there was increased water demand. Almost over half said the set times had increased. And 20 % said the set times had decreased. So there's a lot of variability in set time reporting.

40 % said there was less bleed water. About 30 % said they were seeing crusting. Changes in finishing, almost half respondents. More of our pressure reducers, about 40%. Those are all plastic property changes. Hardened property changes, about half said there was no changes. Like a third said they were seeing random cracking. Less wear resistance, about 20%.

about 20 % said more dusting. So a little bit, like a little bit of everything, some domination issues.

Mike Hernandez (24:55.764)
So this keeps coming back to, in every one of these surveys, at least half the respondents said there was no change. And that's kind of what triggered this, like, why are some people having all these problems and why are over half people saying, there's nothing to see here? Like, what are they doing right? Which triggered this next phase, which is, well, let's try and figure out what they're doing right. What are they doing differently?

Seth (25:26.221)
Yeah, did you have anybody come back? I'm flipping through the survey. So if I'm overlooking it, I'm sorry. As far as finish, something I heard recently was it looks like it's porous on top. Like it's got little tiny holes you can see. Do you have anybody come back and say that?

Mike Hernandez (25:52.148)
you

Mike Hernandez (25:56.724)
So what.

Why are we typically targeting people to respond on as like a hard trial slab? So it would, if you're hard trawling a slab, it would be very unusual to have pores up and up like that. I guess that would be particularly troublesome. Where resistance has been something that's come up like the little.

Commercial robots that take the same path all day, every day on a floor will wear like railroad tracks on the floor. So there's been a fair number of people who've had to do some repairs. So...

It seems like there's been more intermediate aggregates introduced in the mixes than previously existed. There's been...

Mike Hernandez (27:03.732)
disgusting modifiers being thrown in to make the mix more creamy by some teams. Like there's kind of a little bit of everything is some of the solutions I've heard. So that's why this whole AI thing has been like, okay, what's the most likely thing to have happened versus just having 20 ideas and then trying to hit all 20 of them to get the thing at the top of the list.

that's the most likely to help you and leave at the bottom of the list the thing that's least likely to have been a correlation to a mix performing well, just to prioritize transitions.

Seth (27:51.277)
it has

Mike Hernandez (27:51.412)
So right now we just need a whole lot of mixes to be submitted still. So I would ask that your listeners if they haven't already received a request first. So right now I initially reached out to about 200 contractors and I just went last week and kind of reanalyze our lists and tried to, at some point I had put some bumpers on.

The maximum number of participants like per state or per region. Like we have a lot of people in California and Texas because there's such populated States. I mean, two biggest populations in the country. So in New York was number three. So I just said, okay, so we're getting a lot of Texas. Fine. Just increase the numbers of allowable invites to any given States. And so I'm pushing the.

invite out to like 300 contractors. And I mean, within AACC, there's pretty much a whole lot of representation among the biggest, but then also there's a whole lot of contractors that I wouldn't necessarily meet that do plenty of work that just don't engage AACC. So I'd love to hear from them.

The email I'm trying to collect is mixes, -I -X -E -S at AESCC online .org. And if you just ping me on that email, just set up just for this study and I can send them more data about the study itself or just send me, basically it's a submittal package is what I'm asking for. Cause the submittal package will have

You're proportioning, it should have strength data. It'll have a milsor, it'll have the admixtures, it'll have the certification for the aggregates. And that should be enough of what the AI needs to do the analysis.

Seth (30:02.541)
Okay, can you say that email again? It was mixes at.

Mike Hernandez (30:06.292)
ASCConline .org. And if we could put that in the notes for the podcast, that would be great too.

Seth (30:16.493)
Yeah. Yeah, I'll do that.

Mike Hernandez (30:22.324)
So I mean, I've been told there's 30 ,000 country contractors in the US and only 600 of them are ASDC members. So there's a whole lot of people that aren't members.

Seth (30:33.037)
Right. So we're looking for mixes, slab mixes that were successful.

Mike Hernandez (30:41.044)
Yes, slide mixes specifically. I mean, if you have an exterior like a pavement mix, I guess I wouldn't throw it away, but I mean, I'm really looking for interior non -air entrained 3000 to 5000 PSI.

mixes that intended to be hard trialed or trialed as opposed to like a broom finish because if you're broom finishing it tends to be a little more forgiving because you're not gonna give it that final pass

Seth (31:20.973)
And you said you were lacking mostly, is it North Central region?

Mike Hernandez (31:26.452)
North Central, Nebraska, Dakota, Minnesota, Iowa, Pacific Northwest, Montana, Oregon, Idaho, Washington. We have decent representation, a lot of other places.

Seth (31:31.405)
Iowa.

Mike Hernandez (31:44.084)
But I mean, I'll take anything I can get, really. I'd be happy to have it. Especially if it's a good mix.

Seth (31:47.917)
Right. Well, yeah. I mean, do you plan on, are you going to release it once you have all the data for all the regions, or do you think you might phase it out? Cause it sounds like you're getting a lot of data from California, Texas and New York area. I mean, would you release that prior to give people an idea of what you're, what y 'all are seeing?

Mike Hernandez (32:10.676)
So.

Mike Hernandez (32:14.228)
I'm not there yet. So right now I'm just in the raw collection phase and

We're basically the phasing is just get a bunch of the data and then geotech their Roxy is the name of their platform. They're going to crunch the data. And then we have the chairs of the proportioning committee and the ad mixture committee have agreed to take a look at it to make sure that the AI didn't come up with some crazy answer. That doesn't make any sense to validate the conclusions.

And then basically just have a summary report written by probably one of the consultants on 302 committee just to say, okay, here's what we're seeing, but still need a lot more mixes that are doing well. And I'll basically, I'll bounce someone to survey once they give me a mix to say, okay, how's this mix doing? What kind of conditions was it placed in? You know, cause ideal conditions that it did well is

Maybe not super surprising if it was kind of challenging conditions. That would be like really good to know.

Seth (33:31.853)
Yeah. Well, good. Did we cover everything that you wanted to talk about today?

Mike Hernandez (33:39.604)
Yeah, I mean, that was the big thing that's in process. Just the low carbon concrete in general is a super hot topic these days. If you've been to an ACI convention, there's multiple sessions about low carbon concrete and just that there's international and national push and federal funding to try and get essentially less clinker in our concrete.

that comes with its own challenges. And unfortunately, the contractor could be the one left with the responsibility for the bad outcome if they're not focused on, am I doing enough preparation and we're doing testing to see if we can, if this is a placeable mix. Like if you get first time ever out of the box, like you may have.

It may have an issue. I mean, there's, we're recommending that people basically do a mockup. If it's a project that a mixer familiar with in a new area, basically do, if you can get a bleed test, that'd be great. Ideal. If you know the set time, that would be ideal. If you're, if it's setting up in two hours, the test is a five hour set time. Something is happening here that you're not.

could be crusting on you and you're not realizing it.

Mike Hernandez (35:16.66)
Just things to be aware of. And it's a major focus for ASCC. I could see us work on this for quite a while, actually.

Seth (35:26.541)
Yeah, so you haven't released a formal position statement yet for that.

Mike Hernandez (35:35.028)
Well, we did some alerts that were... You did have to be a member to get to those that are behind the log in.

Seth (35:35.053)
Sorry.

Seth (35:38.541)
alerts, right.

Seth (35:43.021)
Yeah, I knew I saw something up. I was on your website. I was like, I was, I was like, we're still at position statement 47. So,

Mike Hernandez (35:54.516)
By the way, the position statements, I did go through the last few months and some of those, the position statements have been written over the course of 20 years. So they're referencing older ACI documents. So I basically went through and if it was referencing 318 from like 2005, I pulled it up to the current 31819. And if it was referenced to like, chapter eight, which is now chapter 26.

to get the current references, current years, current chapters, if the quotes different to fix that. We just updated all the references and they're having translated into Spanish. So by the end of July or sometime in August, we should have all 47 position statements with the most current ACA documents and in Spanish. There's one, which is number six.

that was endorsed by like seven other trade associations. So it didn't touch it because that was a big lift. That was like 2021 to get them to all endorse that. So that's the one while the Florida associations that's not changing the word in that one.

Seth (37:09.453)
I got you. Yeah. That one we've discussed on here. yeah. Well, cool. Well, I appreciate you coming on there. So, I will make sure I put this email address to send the mix designs to, and you'll have, Mike's contact information as well. And the link to, ASCC, I, again, I can't recommend.

highly enough the position statements and now they've it's open to the public so you can go on their website and see it without being a member. That's awesome. I think we could all I was sharing with Mike I used one just a few weeks ago with the client. I don't know if they read it but I gave it to him so I could say I did it.

but Mike, I appreciate you coming on the, on, on the show today. again, I'll give, all Mike's contact information. And then again, please help Mike out with these mixes. send over your information to the folks that have been successful with the new, PLC, mixes and, yeah, until next time, let's keep it concrete.