How Pozzolans Work in Concrete Countertop Mix Design

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This podcast dives deep into the technical aspects of what pozzolans do in concrete countertop mix design, how they really work at a chemical level, and how and why to use them. But it’s not all technical, don’t worry! We also discuss our training philosophy and why having a solid technical foundation will allow you to be successful with any of the great concrete countertop mixes out there.

Do you want to learn more? Our Ultimate Creative Concrete Training is not just a 5-day hands-on class where you meet some cool people and make some cool concrete. It also includes from-scratch mix designs plus the understanding of how they really work. You will learn not just how, but why.

Register now for August 7-11 or December 4-8, 2023:

We also have a lot more information about pozzolans on our website, as well as CSA cements:

Join us LIVE every Wednesday! Click  here for joining info.  To submit podcast topic requests or suggestions, click here.


Jeff Girard (00:00):
Hey, good morning everybody. Welcome to the maker of the Mix podcast. I’m Jeff Girard and Caleb Lawson’s here and he’s on a remote location.

Caleb Lawson (00:13):
Yeah, I’m remote today. Well, a little bit of why I’m, I’m not in my normal spot and why you might see some jiggling. I’m on my phone this morning because we are in Banner Elk, North Carolina on an install of four beautiful fireplace surrounds and unfortunately the job site wasn’t super prepared, so the measurements were accurate and they were ready for us. But there was mean the stone masons had put on lath and stone where they didn’t need to and then they hadn’t taken it back off and there was lumber in front of all of our places we needed to work. And so we spent more than half the day yesterday undoing things to get ready, which if you have been a part of one of the ultimate classes, that’s not really our job. So rest assured, Jeff, I’m charging for it. But we wanted to get the job done, so we’re going back in the morning. Thankfully my wife’s best friend has a cabin about mean, literally one street over from the neighborhood that we’re working in. And so I texted Jen and I was like, please, I, I’m hoping that the cabin is available. And she was like, yes, it’s been just clean. Go use it. So super grateful that was available to us. Yeah, those

Jeff Girard (01:40):
Kind of things happen.

Caleb Lawson (01:41):

Jeff Girard (01:42):
Unfortunately, even if they said they’re ready because I know you checked us to make sure they’re ready and that’s what is the definition of ready,

Caleb Lawson (01:49):
Right? Right. Yeah. So that’s where I am. So that’s also why we’re recording a little bit early this morning. So if you tune in later and you were like, oh my gosh, we didn’t see you at eight o’clock, right? You missed you. We are, sorry, apologize. Did not have time to adjust, but it’s seven 20 and I needed to get rolling back up for the job site. So I want to make sure that we got this recorded and got this up for everybody to watch, but also if need to get back up to the job site. So

Jeff Girard (02:23):
Morning’s topic’s going to be information packed and we’re going to kind of keep it brief first to respect your time to do that. But on the other hand, it’s not a topic that needs an hour long discussion. This is more factual and it has to do with pozzolan or also known as supplementary cementitious materials. So I know we all have experience using concrete that’s made with them. And what I want to do is take a broad overview of talk about, and I’ve said this in class and I’m going to repeat this again here and go into a little bit more detail. What are they, why do we use them? Why do we care? And what information is there that’s out there about them that is technically accurate but not necessarily practically accurate? So let’s start in the big picture. What are they? So these polands or supplementary cementitious materials, and I’ll list a few. There’s fly ash class C and class F flash ash, which most of us don’t use, but it’s often used in the construction industry. There’s slag or blas furnace lag or ground granulated, blas furnace lag. It’s all the same thing. There’s Medicare, there’s silica fume and also a specialized type called white silica fume. And then there’s VCAS, which is a brand name. It’s really an abbreviation for very, very finely ground glass. And there’s a couple types of that and

Caleb Lawson (04:00):
That’s abbreviation for vitrified calcium aluminum silicate.

Jeff Girard (04:03):
Yeah, which has nothing to do with CSA cement or anything like that. Sometimes people get, they hear those letters and they kind of think one thing when they, it’s not. So all these materials, well couple with a couple exceptions, class C flash and slag by themselves, if you just took them and put them in a bucket of water, they would never, ever harden. So they are al all Aly activated. So these materials dissolve when the pH or the alkalinity of the solution they’re in, the mix they’re in is high enough and that’s usually above a 10 and a half pH, which is pretty alkaline. Usually when you make fresh concrete, ordinary concrete, it’s PHS around probably around a 12, sometimes even a 13. Kind of depends on the cement. So that’s very, very alkaline. That’s like draino alkaline. So that’s why you get chemical burns on your hands.

Jeff Girard (05:07):
That’s why your hands feel slippery. That’s the lipids in your skin dissolving from the high alkalinity. So they need alkalinity to start working. Well, where does that alkalinity come from? In a Portland cement based concrete, which most of us use when you add water to Portland cement, you start this chain of reaction, this chemical reaction, and you start generating different compounds. And the compounds we’re most interested in are the calcium, silica, hydrates. Those are the glues that hold everything together. And there’s two flavors. There’s an early one and a late stage one. But combined, they are what bind everything together. They are what we think of as the cement and that’s mainly concerned with, there are other byproducts that are made. One of those is heat and a final one is calcium hydroxide. And calcium hydroxide is a chemical related to sodium hydroxide, which we know of as the brand of drain clear called Drano.

Jeff Girard (06:16):
So calcium hydroxide is generated and it starts building up as Portland cement hydrates. So the longer it’s hydrating, the longer it’s curing, the more and more is building up inside the concrete. Now normally it doesn’t hurt the concrete, it’s not a detriment, but as a material it’s building up inside and it kind of looks like flat hexagonal plates and they’re pretty big compared to the micro structure of what’s happening inside the concrete. All this is super microscopic, right? You can’t see it, but calcium hydroxide is pretty water soluble. So when as your concrete is curing and as things starting to, it’s well past the, oh, it’s already hard stage like at day one, day three, day seven, day 28, whatever, as those crystals start to form, just like if you’ve ever spilled sugar water in your countertop or you’ve seen salt, they put salt on the roads or you put salt on your sidewalks in the winter for ice, as that salty water starts to dry out, the salt crystallizes.

Jeff Girard (07:30):
Well, that’s what’s happening inside your concrete and those calcium hydroxide crystals form on the surfaces of things, just like frost forms on your windshield, those crystals can block the calcium hydra, silica hydrates the glues from bonding things together. They form like a bond breaker. And generally speaking, there’s not enough of it to really weaken the concrete, but you do have these internal bond breakers that are inside your concrete that are also pretty water soluble. So if moisture gets down, like rain gets down inside your concrete because maybe the concrete had too much water it used in it, so it’s got pretty open pores, those open pores lead to or intersect with those calcium hydroxide crystals. The rain gets in there, they dissolve, and now what happens when the rain goes away, the concrete starts to dry out, capillary starts drawing that out and that’s what you see what you call salts or lime or EF fluorescence. That’s the primary reason why you get EF fluorescence is you have all these soluble materials, things that can dissolve easily coming out of the concrete. Okay, what now

Caleb Lawson (08:47):
I want to ask a quick question. So you said it doesn’t necessarily weaken your concrete per se, but the add of what we’re getting at will ultimately strengthen it. Correct?

Jeff Girard (08:59):
Exactly. So if you have it, it’s picture in your head. You’re painting the outside of your house, so you got your house and you got your paint, and if you don’t clean, that’s surface. If it’s dirty and you start painting over that dirt, paint’s not going to stick. Capacity for the paint to stick to adhere is very high, but if you got something in between, it’s just ultimately going to peel off. Well, if you’ve got little spots of dirt here and there, but the rest of it’s clean, then the majority of it’s going to bond well, but it’s not as bonding as well as it could.

Caleb Lawson (09:35):
That makes sense.

Jeff Girard (09:36):
So that analogy here applies on a microscopic level inside your concrete. So when you make concrete let, let’s just arbitrarily throw some numbers out. These, these are just references. So let’s say I’m going to use a fixed low water cement ratio. We’re going to say a 0.30, okay. Some people make it lower and that’s fine, some people use higher, that’s fine, but we’re just going to pick a number. If I don’t use any pozzolan in my concrete, I’m just taking Portland cement and my aggregate in my water and that’s it. And I put that in there as that cement hydrates and glues everything together. Now I’ve got calcium hydroxide inside that concrete and it’s going to give me a certain amount of strength. It is what it is. Doesn’t matter what the numbers are, don’t get fixed on numbers. They’re not that. They are important, don’t get me wrong, but we don’t need to worry about whether it’s 7,500 or 62 50 or 83 75 or anything like that.

Jeff Girard (10:36):
They’re just numbers. So you’re going to get a certain number level right here. So that’s your strength. If I take some of that cement out, take some of that Portland cement out and I replace it with an equal weight of a pozzolan. Now there’s bunch of different pozzolan, I’m just going to generalize here. You replace it with a pozzolan that calcium hydroxide that’s being generated inside the concrete is reacting with those pozzolan. So I I’m taking that calcium hydroxide before it crystallizes and consuming it to generate more of the calcium, silica, hydrate gels, more of the glue so that there’s an engine inside the concrete that’s making more glue from the waste product that would normally just be there. And because I’m making more glue and I’m consuming the things that are forming basically wipe away of the dirt so that when I’m painting, I don’t have that dirt anymore. I now have more surf, more stuff being bonded. Well,

Caleb Lawson (11:41):
Almost like what you’ve done is you’ve applied a primer to the paint that eats the dirt.

Jeff Girard (11:47):
Yeah, exactly. And so now I’m taking full advantage of that cement paste and I can now get much better strengths because I don’t have things taking the strength away. In addition, I’m also helping to fill some of those voids that are there. So the calcium hydroxide takes up space. Everything in your concrete takes up space, water takes up space, sand, grains, take up space, anything that’s soluble that can dissolve hook up space and now it’s gone. So if I replace it with more glue, so now my concrete is more dense, it’s less porous, there’s another term for that. Permeability has a much lower permeability, it’s much less porous. That’s a good thing. So I’m getting all these benefits and as I consume more and more of that calcium hydroxide and I make the concrete less and less porous, that means the chance of f fluorescence happen to outdoor concrete goes down, right?

Jeff Girard (12:49):
So that’s the reason why we use these things, right? We get lots of positive benefits. Now let’s kind of get into the nitty gritty of the different kinds and I’m not going to dive too deep. So the poms that we use in the concrete countertop industry or whatever we want to call our industry generally are white because we want our binder, the cement paste, the cement, the sands, everything would be very light color white so that we have the full range of colors that we want to work with. So there are only three or four white polands. So there’s slag, which is a byproduct of the steel refining industry. SL is good, but it has kind of a quirky effect that because when they refin steel that it’s used to absorb impurities from the raw ingredients if they’re recycling steel and things like that. So it might have copper in it and things like that.

Jeff Girard (13:47):
SL can turn blue or green when it’s cures and it needs to oxidize for that greenness to go away or that blueness to go away. So if you’re interested in, there’s a slag association, just Google like slag, green slag or something like that. So if you seal your concrete before it oxidizes, that concrete may be bluish for a long time and it’s not necessarily a real color. So that kind of keeps a lot of people from using it, but that doesn’t mean everybody doesn’t use it. It’s a fantastic, it’s a recycled product, so it’s a fantastic thing to use. Fly ash comes from burning coal and there’s tons of it and it’s a very, very common pom used in the regular construction industry to replace cement. So cement’s the most expensive ingredient in ordinary concrete, and if you can replace it with a waste product that’s basically free, that’s a good thing.

Jeff Girard (14:46):
Ash is, doesn’t react very quickly. It takes a long time for it to do its thing and in norm, in the ordinary construction phase of, you know, pour something and you might not have to start building something on that or with that concrete for a month or two, it’s no big deal. But for us, we work in days, not months. So we are real sensitive to time and hi ash being a waste product can range in color from a light beige gray to black because of all the carbon from is soot, basically it’s leftover, it’s not soot, but it’s leftover from burning coal. So generally most people don’t use that. Medi kills a manufactured product. A lot of people, some people use that. It was very, very popular in the concrete countertop industry probably about 15 years ago. And it’s an extremely reactive, gives great strength, I guess you could say.

Jeff Girard (15:43):
It’s downside for some folks is it tends to make your concrete thick and sticky, real sticky. So are the kind of characteristics you’re looking for. Metakaolin is a fantastic and a dose of five to 10% is fantastic on that. So another one is white silica fume. So white silica fume is a byproduct of refining special kind of steel. Normal silica fume comes from refining steel from blast furnaces and it’s literally the fumes that come off the open hearth blast furnaces and formal silica fume is like dark gray, it looks like mill scale on hot rolled steel and that’s extremely reactive. It’s a very, very good pozzolan, but of course it’s dark gray, so you are limited in colors. The kind of cool thing about white silk fume is it tends to be pretty white, either pure white or sort of a grayish white. It’s a little bit harder to find, it’s a little bit more expensive and it has some positive and negative characteristics. Silica fume, you have to be very, very careful of how you cure your concrete. It does not like to dry out so you can have problems. So it’s well known in the concrete industry by concrete professionals that the curing phases for white silica fume or silica fume in general has to be paid attention to. So it tends to be used in precast plants where they can do very careful controlled curing, you know, just don’t Well,

Caleb Lawson (17:11):
And certainly we hope that if any of you watching who are artisans are using what we would consider at this point to be common sense curing practices. I mean uncovering your concrete and all of those things, making sure that you’re not just leaving it out to dry out in your shop. Yeah,

Jeff Girard (17:29):
Yeah, that’s very important. And we’ve talked about that and we’ve talked about ways to manage that and we’re not going to get back into that here.

Caleb Lawson (17:36):

Jeff Girard (17:37):
So the pozzolan that I prefer to use, it’s not available to everybody, is VCAS. So this is very finely ground post-industrial glass from the production of glass insulation before they color it and other forms of glass, not like window glass, not flint glass, not bottle glass, that those types of glass have high sodium contents, which is not the best for your concrete. It can cause some issues. So this glass is very low sodium pozzolan and it’s very reactive. I’ve done an ex, I’ve done over years worth of are there

Caleb Lawson (18:19):
Are poms that are made with other glasses and things though, correct

Jeff Girard (18:23):
From, I’ve used some in Australia, I’ve used some in other states where they take ground bottles and I’ve seen, I’ve read a lot of research, I’ve been research, I’ve researched everything, read technical papers and things that are freely available on the internet. So you too can Google stuff and read for yourself. So it’s not like I’m gatekeeping the information out there. It may be a little hard to understand, but it’s out there. There have been lots of research of using recycle glass because so much glass is used and w wipe landfill it. And not everything can be, especially if you commingle glass. Ultimately when you have brown glass and green glass, you can’t make clear glass anymore. And there’s only so much brown glass and green glass that’s or brown glass that’s desired. So well, if you can grind it up and powder, turn it into a powder, you can use it in your concrete.

Jeff Girard (19:16):
And that’s not a bad thing. Usually high sodium GL powder glass pozzolan have clumping issues. That’s what I’ve observed. Anyway, all these have different chemical makeups and you can look on, they have, usually it’s a combination of calcium as they’re ba, calcium, aluminum and silicate. So like glass v a s, calcium, aluminum, silicate, and the proportions of those three prime elements in the glass, in the pozzolan forms, it’s called a turn diagram. So it looks like a little triangle and instead of having like, okay, it’s all of this or all of that, and you’re somewhere on that spectrum, it gets a little complicated, but silica F is like all silica. There’s no aluminum in it, there’s no calcium in it, and Melin tends to have more calcium and aluminum in it, so it has very little silica in it. And then flash is somewhere else. Same with slag. But all, all that means is their components are different and that influences how quickly they react and how quickly they do their thing. And ultimately their purpose from our point of view is they make more glue, they consume that calcium hydroxide and that we make denser, less porous, less permeable, stronger concrete.

Jeff Girard (20:48):
We as artisans, we as manufacturers, the things that are important to us are we want to make our customers happy. We want to be able to achieve the designs that they want us to make. We want to be able to achieve the designs we want to make. Okay? That generally means we want to make strong, high, early strength, low shrinkage, concrete that doesn’t have any kinds of problems. It’s not crumbly, it doesn’t crack, it doesn’t have micro cracks, it doesn’t shrink all those things. And so that’s why we modify our concrete with ad mixtures and pozzolans are a way, a prime way of doing that. So they’re a tool that we use to make our concrete better, and in doing so, we make better products ultimately. And even if you, all this is just abstract knowledge and I’m trying to keep this high level so that we don’t get bogged down in techno babble. That makes me look like I’m super knowledgeable, but it’s irrelevant and confusing to a lot of people because why would you care? You don’t have that background. You can research it and you can learn it. You know, guys are smart, but care, I don’t presume to say, oh, well you should know what this is because it makes me look good.

Jeff Girard (22:06):
Silly, right? I’m here to help. We are here. Caleb and I are here to help you understand how to do what you want to do better. And this little quick podcast here is to kind of explain, dip in, dip our toes into the pool of deep technical knowledge that for a lot of people, I don’t want to say you don’t need to know it, but you don’t need to know it to do your job. It’s nice to know, but it’s not nece. It’s not necessary for you to be able to do your job. So a lot of the information I’m talking about comes from, this is one source, the, I don’t know if you can see it here from the Portland Cement Association Design and Control, concrete Mixers. You can buy this book. Page 67. I’m terrible at doing this. Here we go. Where is it?

Jeff Girard (22:55):
There you go. There you go. There we go. Right? Wikipedia has this picture. It’s all on Google, this stuff. This is nothing new. This is in the construction world, in the real world where they’re doing stuff. If you’re building a skyscraper or a dam or a bridge button or something where you need really high performance concrete engineers, civil engineers like me who have taken classes, done things do mix. We are the ones who do that mix design. We’re creating a recipe. That’s a cool thing about concrete in the building industry is we create the material for the project. So every mix design is unique to a project. So we’ll look at different combinations of maybe it’s silica, fume and fly ash mix with slag and then your cement, because those are readily available locally. We don’t have to import them. And then the end results, the property of the concrete is very, very strong.

Jeff Girard (23:48):
It meets the needs of the project. So that’s why we use them in that kind of concrete. But you don’t use it for a sidewalk because it’s not necessary. We only use it when we’re necessary. Well, for the kind of work that you and I and Caleb do and other folks do, we want very high strength concrete. We want our concrete to perform really well. That’s why we use these things. Now, we don’t all use Portland cement. Some of us only use Portland cement based concrete. Some of us use concrete that has a mixture of Portland cement and csa, which stands for calcium sofa, illuminate cement. Others use just CSA cement. There’s a specific version of it called, it’s a bell light form or bell light phase of CSA cement and the company rapid set. That’s their stuff. You don’t blend that with Portland cement. It’s its own version of it. It’s a slightly different form.

Caleb Lawson (24:43):
So be, just so I’m clear here, if you’re using calcium sulf Illumina as an additive to Portland cement, you would still use a pozzolan in that particular case, correct? Because

Jeff Girard (24:53):
We could, yes. Because again, when you work with Portland cement, you add water to Portland cement, calcium hydroxide, the thing that makes the alkalinity, the activator for your pozzolan a final byproduct of the hydration reaction or it’s warm,

Caleb Lawson (25:11):

Jeff Girard (25:12):
So it’s like, here’s another analogy. You got a fireplace, you got logs in the fireplace, you light the fire, you burn the wood, you get the heat, you get the light, you get the ambience that those are the things you want. Sure there’s smoke. That’s one of the byproducts. But where you’re left over is ash. Calcium hydroxide is the ash of that reaction. It’s the stuff that builds up. It doesn’t inhibit things, but it’s inconvenient, right? Well, if you could add something to your logs, this special log, that’s not a piece of wood, but it’s something else that you put in there and burn along with your logs. As the logs are burning, it’s consuming the ash and turning it back into heat and flame. That’s what polands do inside your concrete. Okay? So with CSA cement, CSA cement as part of the chemical reaction, does produce a little bit of calcium hydroxide, but then it is consumed by that continual reaction to form the final bonding agent, the final hydrate gel. So it’s a very transient temporary production. Sure it makes it, but it’s not available for pozzolan to use. Or if there is, there’s only such a small amount, it’s almost insignificant.

Caleb Lawson (26:36):
I did some research on this to get ready for this podcast. And what I came up with was that I think for practical purposes, saying that it’s not, we don’t do that is more for practical purposes and not necessarily if you want to get into the technical data. It does. I actually, I guess it’s something where we didn’t get in. We don’t get into all a lot of the, it’s like this is technically true, but it’s not useful to you or this is technically,

Jeff Girard (27:18):
It’s a very nitpicky point that is largely moot in the grand scheme of things. Because let’s say I take pure CSA cement, and I’ve done this 15 years ago, I did these compression tests. If you take a pure CSA cement and then you start adding pozzolan to it and you start treating it like it’s Portland cement and you do compression tests, there’s a clear loss of strength because those pozzolans are not being activated. They’re not being turned into the glue that you want because there’s not enough calcium hydroxide to do that. And it’s also well known. So with pH, right, you got to have a high alkalinity for the literally dissolve and they only dissolve at a high concentration of a high pH. So if you don’t have enough concentration, if you don’t have enough high pH, they’re not going to do anything. So all those puzzles I added are just sitting there inert. Well, I’m expected them to turn into cement because that’s basically conceptually that’s what they’re D they’re doing. They’re turning into the glue not happening because the CSA cement, the non Portland cement is consuming the thing that we’re relying on itself. That’s why CSA cements get so strong, so fast. The reactions consume a lot of, they don’t make all these waste products. That’s, they’re a lot more efficient. So it’s a point when we teach.

Caleb Lawson (28:55):
So where you’re getting at is with Portland cement. Calcium hydroxide is a final byproduct with C cement. The transient amount of calcium hydroxide that does get produced is consumed in an early stage of hydration,

Jeff Girard (29:11):
Right? There’s not enough or any leftover at the end to activate your pozzolan and the pH of CSA cement the hardened cs. The fresh CSA cement is much lower. It generally is under 10 and a half. Well, that’s a threshold of pozzolan activation. So the highest pH, the most alkaline cements get, and this is from technical literature, is the minimum threshold for alkalinity that need it much higher. So like, yeah, it’s a very nitpicky thing to say, sure, they make it, but it’s not enough to do anything. And test physical testing bears

Caleb Lawson (30:03):
Out. Well, we can’t say anything. It could maybe do a little something. Oh,

Jeff Girard (30:08):
I’m sure it it’s doing something right. But is it enough compared to Portland cement? No, it’s not because there’s being consumed by itself. Here. Here’s here, here’s another analogy I want you to think about. And this is again, going a little bit off. I’ve got a light bulb and a battery and a switch, a flashlight if you will. So if the switch is off, nothing happens. I turn the switch on, circuit’s closed, light comes on, okay, now I’m going to replace that switch with a glass of distilled water and two metal electrodes in the water. Current can’t flow through distilled water. It’s basically an open switch. Now if I take a big teaspoon of salt and I stir it in there, dump that salt in, now I have an electrolyte. And now current can flow through that. So the light comes on nice and bright, start over with a new glass of water, I use a half a teaspoon of salt, less current can flow light doesn’t glow as much.

Jeff Girard (31:14):
Do it again with a quarter teaspoon, less current flows, the light’s really dim. There’s a point where if you don’t have enough that current flowing, the light bulb to our eyes, the practical sense to our eyes, there’s no light being made. So it’s safe to say nothing’s happening. Maybe some current is flowing so technically, sure, some micro occurrence flowing and it’s producing that filament’s getting a little bit warm. But to our eyes, to the real world that matters. Nothing happens. So when you come to a CCI class, you’re not just standing around with your hands in your pockets, watching people do stuff. You are elbows deep. We expect you to do everything. You’re being taught. Hey, tons and tons and tons of practical information and technical information or more esoteric in-depth stuff is being woven in and out of the class. But your brains are so full, you are absorbing, you’re drinking through a fire hose. I’ve had many people tell me that over there, you’re drinking. I felt like I’m drinking from a fire hose. And it’s hard to absorb that. And I understand that. That’s what a good teacher does, is they understand who is what their students can absorb, what they can take away from this, what’s important for,

Caleb Lawson (32:37):
Well, what they can use going forward mean. That’s one of the biggest focuses is like, yeah, we want to give you a foundation, kind of a bedrock to build your business on. And I think there are some really cool techniques out there that we don’t really delve into that you can get into later. Once the foundation is built properly and in class, we don’t get super nitty gritty into what mix you should use because ultimately that’s going to be a personal choice. Should absolutely. I said this on a sealer question this morning on Facebook, somebody was asking what sealer should they use? And there were a bunch of people that chimed in, and Jeff, I know you chimed in and Tom Fisher chimed in and a couple others chimed in. And I think the answer that Tom gave was essentially, a lot of us are vendors, myself included.

Caleb Lawson (33:38):
So take it with a grain of salt. And my kind of reaction to that was, I mean, super good on Tom for saying that. Absolutely, that’s wonderful. And two, here’s what I use, but you should buy, I mean, I advised the guy, I was like, you should buy several different sealers. You should use them exactly as the manufacturer recommends that you use them, follow every instruction, do it ex to a T, let them fully cure to the manufacturer specifications and then test them yourself. Yeah, and I say the same thing about mixed designs. I’ve landed on the mixed design I use over years of testing. And is this practical? Is this, does it come down to a cost point that makes sense for my business, but I don’t want to cut cost just to cut cost? Does it work for that? Right? Does it meet all of these criterion?

Caleb Lawson (34:40):
It obviously, does it get hard? That’s kind of important. And then how flexible is it? Day one, am I risking a crack by flipping it? Flipping it over day one, how dense is it when the customer knocks on it, I do want them to hear a sound. I want them to feel like it’s solid. So that’s a factor. And so there’s all sorts of factors that over the years I’ve kind of eliminated from my repertoire, absolutely, because I’ve tested them. And so if somebody asked me, what mix should I use as the burgeoning artist, I’m not going to just blindly recommend you something because I use it, here’s what I use. But please go buy all of them.

Jeff Girard (35:21):
Try and

Caleb Lawson (35:22):
Test them for yourself and see which one you like the best.

Jeff Girard (35:24):
So getting back to and tying back into this, one of the mixes we use in class, we just did a big event where we cast this 16 foot table, double eight foot. We use Rapid Set CementAll, right? A lot of people use it. I like it. It’s convenient. You buy it at Home Depot. It’s relatively inexpensive. It’s incredibly strong. I have a lot of experience with it and I count on it, it have downside. Sure. Do I use poms with it? No. Do I tell people, don’t use poms with it. They don’t work well, getting back to the pozzolans don’t work in CSA cement because CSA cement consumes whatever hyd calcium hydroxide is generated by that reaction. It consumes a fair bit of it. How much? I don’t know. All I know is from my own personal tests that not enough calcium hydroxide is left over to activate the POS that I add thinking they’re going to work and they don’t.

Jeff Girard (36:33):
So instead of going off on a very technical tangent and getting down in the weeds of, well, they do work, but only a little bit is activated, but I can’t tell you how much, and it depends on the positive. You’re using all those little specific exemptions, you are already lost. Right? Again, coming back to, as a very experienced teacher with a lot of experience and a lot of technical knowledge, I have to look at what is the person receiving this information? What do they need to know? What are they capable of absorbing? What is going to be useful to them that they can remember? So I can go on a half an hour lecture on the chemistry of cement and what could and could not happen, kind of like what I’m doing now. Or I could just say, look, if you’re going to use this product, if you’re going to use cement all, let’s say don’t use pozzolan.

Jeff Girard (37:34):
And it’s much easier to remember that they don’t work as, sure I’m over oversimplifying. But it’s a practical thing. So you can be technically accurate or you can be practically informative. And for a lot of folks, all they need to be is practically informative and they’re relying on our expertise and our professionalism and our wholehearted sincerity to want to be helpful and give you real unbiased information that we’re not just pulling out a thin air to push our own agenda. It’s like, look, these are how, these are the things we use. This is how they work. This is why the tagline of CCI is, it’s not just how but why is the hardest question to answer. How is easy? And that’s kind of one of the differences we like to come from is, you know, ask us a question of why. We’ll let you know. If we don’t know, we’re going to find out.

Caleb Lawson (38:37):
Well, and I think too, the thing is, if you don’t trust what we’re saying, if you think that we’re being deceitful or whatever, go test it. Make yourself some of this concrete and test it for yourself if you want to dig in. And that’s one of the things I dug in because I wanted to make sure that I wasn’t misinforming people. Cause that’s super, super important to me that if I tell somebody something, I’m honest. I want to give people who come to CCI classes, people who ask me questions, I want to give them the best practical information I can with the most accuracy I can. And the most honesty.

Caleb Lawson (39:19):
Most honesty being a hundred percent, that gives them a leg to stand on a foot to a foothold to be successful in this industry. And so I get super concerned that the information I’m giving is accurate and correct. And so I really, really dug in and that’s what I found in my research as well. Not that Portland Cement Association doesn’t know what they’re talking about, but I was encouraged and I would encourage you watching to research it for yourself. The technical data and the white papers and all of that are out there and it’s a little bit weedy. You have to really kind of slog through some of the technical data. But that’s what we talked about today is exactly the information that I came up with in my own independent research in addition to this. So yeah,

Jeff Girard (40:14):
And I’ve had the good fortune of, I learned this, gosh, when was this? 1986. That’s when I learned it in school. So yeah, I mean, learning about the material you’re working with I think is good. I think it’s important to understand what’s actually happening. The more you can master the material, and I, we’ve said this in prior podcasts, the more you can master the material you’re working with, the more you can do better things with it, the more you confidence you have in your material. But also the more you understand, the more you can sort the wheat from the chaff. And,

Caleb Lawson (40:58):
And something that I would add, Jeff, as we kind of wrap up and I do need to run here shortly. Sure. Something I would add that you said the other day in a conversation with me that really stuck with me is that back in 1980 or whatever, when really Buddy and Fu-Tung were up there making stuff, it was really, really important to, because there was a lot, weren’t any mixed designs, you had to have your own. And so today there are I

Jeff Girard (41:39):
A lot of choices.

Caleb Lawson (41:41):
Six, a lot of choices. I dunno, there are 5, 6, 7, 4, 3, I don’t know, there’s a, there’s a multitude of actually really quality mixes that we can choose from. And a lot of artisans, I know friends of my close friends of mine use mixes I don’t use, I know offhand three or four different people that use three or four different mixes designs. And they all make really good concrete. One of my best friends uses one of the Buddy Rhodes blended products, and it’s not the GFRC mix. And he makes really quality concrete. And I use the Alpha line and I like to think that I make really quality concrete. And so there are plenty of others out there. There are, there’s, and we could name them all off for sure, but they’re five, six or seven really high quality mix designs that if you buy them and you use them the way they’re supposed to be used, then you’re going to end up fine.

Jeff Girard (42:41):
And so CCI has always been, we try to stay objective and not push an agenda and certainly not force you to buy a certain product line or do anything like that. And I don’t want to get into product development or anything like that because in the end, what we make and how we make it is just as important as what we make it with. So you can do a lot of things with different mixes, interchanging them, and every mix has subtle differences. Maybe this one’s easier to hand pack and that one’s easier to make flowable and this one sets up a little quicker. Or this one has different characteristics or that one smells different than another one. Whatever. They’re all slightly different. It’s like cars. You can get into any car in a parking lot randomly, and as long as you can get in and drive it, it’s going to take you where you want to go.

Jeff Girard (43:42):
But they’re all going to feel different. They’re going to handle different, they can do different things in terms of pickup truck can carry more sheets of plywood than a convertible can, but they all will transport you from A to B. So if your minimum requirements are to just do something, you could probably close your eyes and pick anything. But as you get more and more specialized, it kind of behooves you to understand what’s going on inside your concrete. But that doesn’t also means that there are some, you have still have good choices, you always have multiple choices. There’s no one perfect mix for everybody, for every application. And pozzolans are a core ingredient in all of these mixes. And I just wanted to share this kind of technical background information with you. How do they work? Why do we use them and when do we not use them?

Jeff Girard (44:36):
Again, if you’re blending Portland cement and CSA cement, which something that I don’t care to do because it’s like why bother? But some people do, right? They have good reasons to then sure at apom, because the pozzolan cement’s going to be generating the calcium hydroxide, the pozzolan need, but in a straight CSA cement CementAll use them. Sure, maybe a half a percent of your POM gets consumed and helps, but the rest of it doesn’t. And we’re using a higher dose 5, 10, 15, 20% sometimes. So the rest of it becomes in our stays in our, and doesn’t really help anything. So in practical sense, that’s where that don’t use CSA cements don’t react because they consume most of it. They got off the track. I don’t want to go on this anymore. I know you got to run. So we’re going to wrap up today and thanks for joining us for this week’s Maker & The Mix.

Caleb Lawson (45:40):
Have a good one.

Jeff Girard (45:41):
Take care.

Caleb Lawson (45:42):
See ya.