This week’s episode is “Polymer: Who needs it?”. It explores how polymer works, why and how it is used, and the philosophy of relying on science and engineering for good concreting practices.
For more information about polymer, see this article.
Jeff Girard (00:03):
Good morning everybody. This is Jeff Girard and Caleb Lawson, and we come up with a name for our podcast. It’s called The Maker and the Mix, because we’re not just talking about concrete, we’re talking about us, the makers too. So welcome to our second podcast.
Caleb Lawson (00:22):
Yes, welcome. Excited to Patty. I’m interested to see who joins. I don’t know where the link was posted. I know Lane posted it, but I’m not a hundred percent sure where that happened. So I’m excited to see whoever joins and
Jeff Girard (00:44):
As we get our podcasts under our belt, we’ll have more people reading, watching, listening to these and perhaps joining in as a conversation.
Caleb Lawson (00:55):
And maybe I’ll get my camera figured out. It’s just moment we’re rolling with it. But
Jeff Girard (01:02):
We’re makers, not studio executives or actors standing in front of camera preening For the audience, we’re just here.
Caleb Lawson (01:15):
Maybe I preen
Jeff Girard (01:16):
Need to could tell he’s clean shaven. So today’s podcast, today’s discussion is
Caleb Lawson (01:24):
Polymer. Who needs it?
Jeff Girard (01:25):
Yeah, polymer. Who needs it? What is it? Why do we need it? Why do we use it and why is it not used in most concrete? So before we jump into it, before we get into the chemistry of it and the different kinds of polymer out there and all the this and that and the why’s in the wear force, I’m going to roll the clock back to when I got, certainly not when I got started in concrete, but when I got started in this kind of concrete, that was back in 1999, back in the old days, the prehistoric days, the Buddy Rhodes and the Fu Tung Cheng days when
Caleb Lawson (02:02):
A dinosaur, he might be offended.
Jeff Girard (02:06):
He is a legend.
Caleb Lawson (02:08):
Or are you calling yourself a dinosaur?
Jeff Girard (02:10):
I’m calling myself dinosaur. Nice. I’m older than you, but I’ve been around for
Caleb Lawson (02:17):
Everybody. We love you.
Jeff Girard (02:19):
Back in the old days, just after fire was invented, the kind of concrete we worked with was very close to conventional concrete. So I mean conventional, concrete, it’s the kind we structural engineers design things out of anybody who works with concrete as a trade, boring foundations, roads, crafting bridges, or even doing something as important, but simple as pouring a patio or a sidewalk that’s conventional concrete. The kind that comes from a batch plant is mixed in a, well, it’s already mixed, but it’s put in a truck, it’s delivered and then it’s delivered by shoot. Right? So that’s conventional concrete. Your Quikrete five thousands and your Sakrete and your whatever version of a home center is an approximation of that. And they’re, as we discussed in the last podcast, they are made for a purpose. They’re made down to a cost for consumers to use to cast things like a sidewalk or poor fence poster, things like that. Well, getting back to more conventional concrete, the things you cast tend to be rather large, have a high volume and have a certain set of performance characteristics that are not made necessarily clearly defined, but are well understood. If you’re pouring a driveway, you’re probably going to be using at minimum 3000 psi concrete, probably something higher. Maybe your local codes or your local convention of what you like to do creates a higher concrete, has more cement in or whatever that slabs going to be probably four inches thick, maybe more. But now
Caleb Lawson (04:15):
Interjection four inches thick is pretty thin in that world, correct?
Jeff Girard (04:20):
Yeah. When I talk to other fellow structural engineers and other professional engineers and I tell them what I do, their reaction is quite shocked because in the structural world, in buildings, in the real world, four inches is considered structurally very thin. You don’t make things much thinner than that. Now, nowadays with like U H P C and things like that, there are structures that are made thinner, but in normal parlance of things you make out of concrete, four inches is quite thin. Six inches, eight inches is more conventional. Now the reason why I’m mentioning this, the reason why I’m bringing this up is it leads to the root reason why polymer is used in some kinds of concrete and that has to do with curing. Now, as we all know, concrete is made up of several key ingredients and then additional ingredients that you could almost consider spices that enhance the mix.
Jeff Girard (05:31):
And for us, pigment is one of those spices, one of those admixtures that we use to change the characteristics of the concrete. And that’s purely a decorative thing, has nothing to do with its strength or its durability, it’s just how appealing is it? Do we want it to be pink or do we want it to be gray? Do we want it to be green? Whatever, right? Other ad mixtures like superplasticizer or shrinkage reducing admixtures or pozzolans, those are ingredients. Pozzolans are little more than an admixture because they react with the cement, so they count as cement. Those are ingredients that modify the characteristics of the concrete, the workability, the strength characteristics, the durability and all that. Okay? None of those matter. None of those matter if the two most important ingredients don’t react properly. And those two ingredients are your water and your cement because those create the glue that holds it all together.
Jeff Girard (06:36):
Those create the whole stew of chemical compounds that your pozzolans react with that bind everything together that create the properties, because otherwise if you didn’t have those, you would just have sand. And if you are making concrete with rocks and it rocks and all the other things, so it’s the cement and the, the cement and the water are the two most important ingredients. They are the foundational ingredients that everything else depends on. And if those ingredients are not mixed properly, if they’re not proportioned properly upfront, you’re going to get poor performance. You’re not going to get the right kind of characteristics. So that’s where water cement rate water to cement ratio comes in. So if you can control the amount of water you put into your concrete, you’re controlling and to some degree predicting the net characteristics. How strong is it, how durable is it, how porous or non-porous is it? All those things. But that’s not enough. I mean, when you mix your concrete and you proportion all your ingredients very carefully, you are just setting the stage. It’s like you’re preparing a race car for the race,
Jeff Girard (07:54):
But unlike preparing a race, well just like preparing a race car, you still have to navigate it. You still have to drive it. You still have to win the race. And everybody’s goal is to be first. And the last thing you want to do is be last or crash and be out of the race before it ends. And this is where curing is very important and this is something that’s often overlooked even in the real world. Curing is not paid attention to because it involves attention and time and those are things that a lot of people either don’t have or not or are not aware of, or maybe they just don’t care and they’ve gotten away with things and that kind of, well, it worked last time, so I’m going to keep doing it. That approach is a bit of a gamble and it doesn’t work for everybody.
Jeff Girard (08:46):
So this is where polymer neatly dovetails into things. Before I get into that though, I’m going to stick with conventional concrete. You don’t polymer and conventional concrete, you don’t use polymer in a driveway. I mean, first of all, in G F R C, the polymer is about a third of the total material cost of that in group, that mixture. So it’s very expensive. So using polymer in a conventional concrete would make it cost prohibitive. It would be too expensive to do. The second reason is when you have a very thick mass of concrete, a four inch thick slab or a six inch thick slab or an eight inch thick slab, you’ve got a huge volume and there’s a lot of water in that, especially conventional concrete has a lot of water in it.
Jeff Girard (09:35):
That excess water that’s in that mix is basically a reservoir. And where does water go as your concrete cures? The chemical reaction consumes some of that water, but that’s only part of it. Everything else is called water of convenience. You’re adding extra water to increase the workability, and that’s why you’ll see people with a hose just adding water because hey, we want to make the concrete more workable that that’s really bad because you’re diluting the glue and everything else and you’re creating more open space, you’re displacing all those particles that want to come together and form a tight matrix, making a more spongy and open pore structure so the concrete’s more porous. All that excess water can leave more easily because there’s bigger channels for it to escape. But where does the water go away from that excess water? That’s not part of the chemical reaction that leaves through the surface.
Jeff Girard (10:37):
So the surface of say, a driveway, the water can leave through the bottom into the gravel base or through the air up top. If you’re pouring a floor and you’re pouring against say a plastic vapor barrier, the purpose of the vapor barrier basically keeps the moisture from the ground getting into the concrete so that slab doesn’t stay moist over its lifetime. But it also does. Another thing is it seals the bottom of the slab so the water can’t lead through the bottom. It only goes one way. Okay, so that’s a convenient thing. That’s like half your curing and oh, there she is. Oh, hello.
Jeff Girard (11:25):
Can you hear us lane? Anyway, I’m going to keep going. Lane, can you hear us? Oh, she left. She left. Okay. I’m not sure if everybody could see that or not, but I could see it. And Caleb, you could see it so maybe they could. All right, so when I got started making concrete, the standard thickness was pretty thick. Some people cast three four inch thick solid slabs, inch and a half, two inch thick slabs were more common. And so what I’m getting at is the slab thicknesses were quite thick. And if you recall of how a slab works in structural, how it behaves structurally in in flex because everything we make, I’m going to use a book as an example. We cast a flat panel or maybe it’s a wall panel, maybe it’s a countertop slab, maybe it’s a tabletop, everything. Here we go, okay, everything we do is a beam.
Jeff Girard (12:37):
Once it is lift picked up and lifted and moved around. So when you have a slab that’s lifted and picked up, it’s exposed on all sides. It’s flexible and it needs to be strong enough to be able to resist those loads. So when a beam is lifted, it flexes and when it flexes, that one side is in compression, one side’s intention down here. And the tension side is where you would put your structural steel rein like rebar and structural wire and things like that. Or if in the case of geo first you put your scrim, okay, the top surface, the extreme surfaces are where most of the work is done, where most of the strength is resisting. And as you move closer to the center of the slab, no compression, there’s no tension. So the actual center of the slab, the middle of that slab does no work.
Jeff Girard (13:39):
So if you have a thick slab that is full of water and only the surface is drying and that moisture at just under the surface is being replenished by the thickness of the slab, it takes a long time for that surface to truly start to dry out to the point where it doesn’t cure right moisture from the center, it’s drawing it from the center where the strength is less important and keeping that surface layers that are important that allows them to keep hydrating to gain strength. Because that’s the whole thing is when you cast concrete, the moment you cast it and the moment it transitions from a liquid to some a solid, it basically has no strength. And then a few hours after it gets hard, it’s very, very fragile, it’s very weak. And over time that all those calcium silica, hydrate gels start meshing together to form a solid, to form a strong, solid.
Jeff Girard (14:43):
And time is a factor where different mix designs and different water cement ratios achieve different curing rates, right? Curing is the act of the chemical reaction happening and your concrete getting stronger. It’s really important. So if you thin slab, if you a thin slab like three quarters of an inch or half an inch, the distance between the center of that slab and that face is very, very short. So that water doesn’t have a long path to go to leave. So that slab is going to dry out and drop below that critical threshold where the cement inside that concrete doesn’t have enough moisture to keep that chemical reaction growing.
Jeff Girard (15:37):
Some of you may have seen my presentations either a world of concrete or in my classes where I kind of relate that cement particles are like tomato seeds. I want to eat a tomato, so I plant a seed in the ground and I want that plant to grow so it makes tomatoes that I can eat. Well, when you plant a seed in the ground, you need to water it. You need to keep it watered for the plant to grow. And if you stop watering that plant, it dies, right? That’s a bit of an extreme example, but it gets the point across is your cement hydration is important and if the moisture levels inside your concrete drop below a critical threshold and it doesn’t take much for it to drop to where that chemical reaction basically stops, you’re not getting the strength expecting. The concrete might feel hard, but it’s not strong.
Jeff Girard (16:33):
So you can’t go often go by just how does it feel? You can’t go by a kind of seat of the pants, wrap your knuckles on it and go, oh, it’s hard, therefore it’s strong. Only testing will show that. And that’s just impractical for a lot of people. So the best way to make sure that your concrete is strong is through a prescriptive way of, Hey, we we’re cast or concrete, we’re going to cure it properly. Now we all know when you cast concrete, you, once you’re done casting, you cover it in plastic to trap the moisture under that plastic and maybe you put some blankets on it to help trap some of the heat that is generated during the hydration. Because as cement hydrates, it undergoes heat process that I don’t want to get off on track here, but curing under plastics is just the beginning. If you don’t have polymer in your concrete and you’re casting something thin and you’re using Portland cement, you still need to then maintain that moisture level around the outside of the concrete so that the moisture that’s inside your concrete doesn’t evaporate leave and threaten the strength of your concrete.
Caleb Lawson (17:42):
So what would you say? Let’s say for the sake of argument that you don’t have a problem in it
Caleb Lawson (17:48):
And you’re creating a, let’s call it an inch and a half thick piece of countertop. But the way that we do it, of course your edges are going to be built thick and your field, if you will, is going to be left at three quarters of an inch thick. So let’s say that that’s your eight foot by two foot slab, let’s call it countertop, kitchen countertop, 25 and inches. You don’t have polymer. So you’ve covered it in plastic, you have covered it in blankets to keep some heat in without polymer to gain the same amount of strength that you would have with polymer. How long would you need to keep it covered and would you need to do anything additional over and above keeping it covered in order to have that same level of strength and work?
Jeff Girard (18:33):
So that’s an excellent question. I’ve done, I’ve been doing lots of flexural tests. I’ve done probably close to 1500 flexural tests over the last almost year in developing my own products. But what I’ve seen is that if you have identical mixes, one with and one without polymer, and you look at say their seven day strength, you will lose at least 25% of your strength if you don’t use polymer. And that’s
Caleb Lawson (19:09):
Exact same curing technique. So
Jeff Girard (19:11):
Exact same curing techniques, which is cover their piece and plastic overnight, mold it the next day, and it’s sitting in your shop,
Caleb Lawson (19:20):
Jeff Girard (19:21):
Caleb Lawson (19:22):
And really from art standpoint, that to me, I don’t know that I care so much about 28 day strengths. I mean, it’s ninth number to note, but for me as an artisan, and I imagine most of you practical full strength is five to seven days because that’s when I’m moving it to install it, right? Sometimes before. So your practical maximum strength, obviously it can keep you gaining strength and all of that, but your practical maximum strength is somewhere within the first week most sometimes in the second week. And so my question then kind of coming back to it is, so there’s the difference between polymer and no polymer with the exact same cure. What would you have to do to a no polymer concrete to get it to the level of polymer concrete? So how long would you have to leave it covered? So there
Jeff Girard (20:15):
Actually is a standard for that. The Precast Concrete Institute, this happened to be one of the books that I use a lot and get in frame. There we go. I’m backwards. This, you know, can buy it online. I think maybe still anyway, there’s a standard for curing polymers and grc and we’re kind of getting into answering the question, what is polymer and who needs it by talking about why it’s important to make? And this is specific to GFRC. So again, the world of GFRC comes from the commercial world where building panels, things like that to achieve a, because if you’re making a building panel that’s going up on a building and it’s got to survive 20, 30, 40 years, they are interested in long term strength. So that’s the main focus and that’s why the 28 day compressive strength is used so much because the performance of a structure is more important in the long term to the people who use it and to the public in general than it’s say one, three or five day strength is now to the people building this structure, the 1, 3, 5, 7 day strengths is extremely important.
Jeff Girard (21:39):
And those of you who have ever done like SL, cast multiple floor buildings, you need to know what the one day three day strength is. So that when do you strip the forms? And so the, there’s the maturity method that’s used to determine all that. And I’m not going to get into that, but it’s important to know what its short-term strength is for the people making it. And it’s important to know what its strength is to the people using it. So our needs are a little different from our customers. And if our concrete is strong enough for us, it’s definitely going to be strong enough for the customers who are using it in general. I’m making
Caleb Lawson (22:18):
Generalization. It’s like, can I handle it? Can I get it into the house? Is it strong enough for those practices? Because that’s the most stress it’s ever going to be under, in most cases a countertop or whatever. I mean a table, this has seven foot span, I can sit in the middle, but maybe I shouldn’t sit in the middle of day one or whatever, but
Jeff Girard (22:39):
You got to handle it. The
Caleb Lawson (22:41):
Jeff Girard (22:41):
You got to be able to demo it, you got to handle it. In the last podcast I mentioned that that slab that was being installed and it snapped in two, that’s a catastrophic failure that you don’t want to have happen because it’s going to cost you a lot of money, you know, spend all the time to build the form and buy the materials and cast it and all the labor and things like that. But not to mention the loss of business or anything like that.
Caleb Lawson (23:14):
But my point, getting back to again, cause it’s not going to be pr, I understand the standard is probably cure for seven days in a hundred percent humidity environment at all. That’s obviously enough practice for us. But is there a point, let’s say if I were to leave my slab under blankets, maybe it’s a heating blanket and plastic for 48 hours, would that be enough or 72 hours? Or would 17 or 18 hours be enough? Is there a point at which not using poly work does not become a detriment?
Jeff Girard (23:54):
Yeah, I’m not skirting the issue. I keep getting off track. The answer is this, the performance specification written by P C I for curing polymers, and that’s what we’re talking about is curing polymers, not bonding agents, but curing polymers is to achieve the 28 day flexural strength of your concrete. Again, the long term, right? It’s bending strength. You have to wet cure that concrete for seven continuous days and then let an air drive for the remaining time for that concrete to equal the strength of the same exact mix that uses curing polymer in it. That is only cured under plastic for one day and the rest of the next 27 days are air cured. So the difference is six days, six day difference. And that’s for the kind of concrete in the thicknesses, we make three quarters of an inch, one inch thick, that sort of thing. Not fixed labs, not something else. It’s a direct comparison to what we’re making. In fact, those of us who use G F R C, at least the stuff I teach, I teach with a commercial mix. And the reason why I teach with a commercial, I’ve tweaked it a little bit, but the reason why I’m using a commercial based mix as a foundation of my mix design is it works and there’s a huge
Caleb Lawson (25:27):
Jeff Girard (25:28):
Evidence, body of test data and real world actual stuff that’s out there for the last 40 years. In fact, I was reading some research papers that were written in 1981 this morning, so going back 40 years plus about G F R C. So this is a situation think
Caleb Lawson (25:50):
That would make it out date that it’s
Jeff Girard (25:53):
Day, well, if it ain’t broke, why fix it? I read a comment this morning about somebody was talking about fibers and we’re talking, it was about fiber loading and the typical G F R C pre-mix load is 3%. And the comment was, well why do you need 3%? What are you making? So the point of that was, hey, I get away with 2%. Everything I do works with 2%. Why do you need 3%? And that’s an excellent point. If you’re not making anything that demands a lot of performance, then you can get away with a lot. But if you do suddenly start to make that does require a lot of performance, then you better pay attention to the details and understand why you’re using it. So let’s get back to the original question, Palmer. Why? Who needs it? Well, we’ve kind of started to answer that question.
Jeff Girard (27:02):
The role of polymer, and there’s lots of different kinds of polymer in GFRs in concrete, is as a curing agent, as a means of, and its sole purpose is to slow the evaporation rate of the water that’s in your concrete. It’s like an internal curing membrane. It’s like that plastic that you put on overnight, but it’s there all the time. That’s its job polymer does not make your concrete stronger. What it does is it keeps your concrete from getting weaker by drawing out. And that’s a big difference. Poly polymer also doesn’t prevent curling or shrinkage or anything like that. That’s either, that’s usually from poor curing practices or for some other factors that don’t have anything to do with the polymer because the polymers throughout the whole slab. So it’s acting equally everywhere.
Caleb Lawson (27:58):
Well, I mean if you leave your eight foot slab under infrared heat, extreme infrared heat overnight, like it’s going to curl. Cause you’re drying out on the top surface.
Jeff Girard (28:06):
Jeff Girard (28:16):
I mentioned there’s different kinds of polymer. In fact, I a, I’ve had read this book for a long time, handbook of polymer modified concrete and mortars properties and process technology. So this is a very dense textbook on chemistry and the different kinds of polymers. We use acrylic polymers in G F R C and in other kinds of concrete that are for curing purposes. But not all polymers do that. There’s EVAs ethylene vinyl that state, I should have looked this up and I can’t remember because I don’t use ’em. But there’s EVAs and PVAs and Styron, Betadine Rubbers sbr. There’s natural latexes. In fact, the very first recorded instance in the technical papers for using polymer in concrete was in 1923 with natural latex. Rubber didn’t go very far, but it was an experiment. And the most polymers that are used in other forms of concrete are as bonding agents, as glue, as adhesives, thin sets, micro toppings, self-leveling overlays are full of polymers. And in those instances, those polymers are used to glue that new stuff to the old stuff. And they’re typically a very high solids content. So some mixes might use 10% solids might use 20% solids. I’ve seen some mixed formulations that use up to 30% polymer solids in the concrete, and that’s going to make the concrete really rubbery and flexible and have all those great properties that you want for things like a micro topping or a self-leveling overlay because you don’t want it to peel up or flake off or crack because the substrate moves. No,
Caleb Lawson (30:08):
It’s almost taking on the characteristics of the polymer at that
Jeff Girard (30:11):
Point in those specific. Absolutely. But like for G F R C, even using the commercial polymers like Forton and Polyplex, there’s a few others, those are only used at maybe a five or 6% load. So in that instance, the characteristics of the concrete are still dominated by the concrete itself. Your concrete formulation structurally, EM mean is largely influenced by what you put in it. Now, your personal interaction with the concrete is going to be affected by the polymer and by what polymer you using. There’s a big difference between liquid polymers and dry polymers and the way they disperse and all that. And I’m not going to get into that here, but if you’ve kind of grown up using a liquid commercial G FRC polymer, I’m just going to use Forton as an instance because that’s common. I have a lot of people have used it. It’s not the only one on the market. Your personal experience as you’re working with it is it tends to be really sticky. Feel free to interject your reactions. The concrete tends to be kind of foamy and spongy and things like that. And those are not necessarily the most desirable characteristics. Well, for the kind of concrete we make
Caleb Lawson (31:30):
Air it entrains there it seems like. So you get less dense concrete
Jeff Girard (31:34):
With it. It does
Caleb Lawson (31:36):
In my experience, than you do with the dry.
Jeff Girard (31:39):
And that, a large reason for that is that polymer was developed in conjunction with the development of G FRC for the commercial world. And the equipment used to cast it, which is the large peristaltic pump sprayers. So everything about G frc, the entire world of G F C is a system. You got the ingredients, you got the mixes design, you’ve got the equipment, and that’s all tailored, very carefully tailored to do one thing we don’t do. A lot of us don’t use that. So when you take away the spraying effect from that high pressure, high volume sprayer, you lose the ability to purge the air. And if you’re just doing direct casting or things like that, now that air that’s being whipped into the concrete stuck there stays there.
Caleb Lawson (32:31):
Right. Well, and I wanted to make an interesting point. I was thinking about, okay, we as a tie society I think are always after, okay, the new next best thing. And that’s a good thing. Our computers are always being upgraded, our cars are always being upgraded. But then I think also about, for instance, Mercedes-Benz Love Mercedes-Benz, but typically the technology in a Mercedes-Benz is seven to 10 years ahead of its time. They are on the cutting
—– technical difficulties —–
Jeff Girard (00:02):
Okay, here we go. Now we’re recording again. So, alright, so a little technical glitch there. No big deal. We’re going to keep going. So
Caleb Lawson (00:11):
I like them and they’re on the cutting edge almost always of technology inside the vehicle. Now what I have observed is that that is a point of failure in those vehicles
Jeff Girard (00:28):
Being leading edge sometimes
Caleb Lawson (00:30):
And that technology is going to end up in a Ford in eight years.
Jeff Girard (00:35):
Caleb Lawson (00:36):
You think about autopilot, I mean Mercedes was one of the first to have a cruise control that was automatic. And so where I’m getting at is being on the bleeding edge is awesome and really exciting, but it does have detri detriments that you don’t know about until it’s in production. So in theory, all of this is super, super exciting and cool and in practice it might also be super exciting and cool, but it might have a failure point that we don’t know yet. Now contrast that with the small block Chevrolet V8 motor, right? The three 50 small block Chevy, it’s gone through several iterations. I mean there’s fuel injection that’s been added to it, but the bare bones of the engine block are identical to what we had in the Bel Air in 19 feet fifties
Jeff Girard (01:29):
Push rock technology.
Caleb Lawson (01:31):
And so my point, progress is super, super important, but so are the roots, right? Chevy GM would not still be using that motor if it what, because they’ve got an enormous r and d department that is spending tens if not hundreds of millions of dollars every year on developing better technology, right? Vehicles, I mean the car, my wife has a 2015 Yukon. It has a 5.3 liter v8, which is based on the Chevy small block. So it’s not a three 50 anymore. I don’t know what the cubic inches are, but it’s the same block roughly. It’s based on the same technology. Now it has technology that shuts down four the cylinders when you’re on the highway from go fuel economy. That was possible, but actually that was possible in’t say Lincoln tried to do it in the seventies,
Jeff Girard (02:23):
Least in the eighties.
Caleb Lawson (02:27):
But my point is technology’s been updated, the engine blocks remain the same and despite spending tens of hundreds of millions of dollars a year on r and d, they’re still using that engine block, which tells you the engine block is a valid base. And so taking it back to concrete, yes, my question earlier, well as the 1980s ancient history, is it too old? Is it gone? Whatever. No, they have it there for a reason and there are companies spending tens of hundreds, millions of dollars on research and development to make concrete better for a building material because it’s been used for thousands of years going to stop tomorrow and they’re still using polymer for a reason.
Jeff Girard (03:03):
Absolutely. That’s a really good point. I think the way, my point of view and it’s important to me, context is extremely important because if you make a blanket statement that’s a standalone statement that you don’t paint the bigger picture that that statement is colored by. You don’t really know where somebody’s coming from or what that statement’s all about. I’m speaking to people who do this as a business. That’s what CCI i’s. Job is to help people succeed as a business, not to do it as a hobby, not to do it because it’s fun not to do it because you want to be a mad scientist in your garage. Those are all great reasons. But when you run a business and when you want to run a successful business and Caleb, you are definitely somebody who can speak currently to this running a very successful concrete countertop in architectural, creative, concrete business. Every decision you make is colored by the fact that you’re running a business, you’re not playing, you’re not tinkering, you’re not creating, you’re doing creations and you are creating, but you’re doing it for a reason. You’re doing it to make money, you’re doing it to run a business so that you can be profitable, that you can grow, you can feed your family, you can support your employees and businesses can’t afford to make decisions that can lead to expensive costs and failures down the line.
Caleb Lawson (04:55):
And I would add to that might lead, right because
Jeff Girard (04:58):
Might it’s lead,
Caleb Lawson (05:00):
The reality is maybe you’re in a super friendly environment to curing concrete. Maybe you’re in Florida and it’s super crazy high humidity. So that aids in the curing if you’re concrete, it helps it to stay at a higher temperature for longer if it’s covered and things of that nature. If you’re in Nebraska in the winter, these things are, you have to do more, right? To make your concrete cure problem then you would in Florida, I mean when I was in Florida, I never had to do any more than cover my concrete with a piece of plastic that was enough. It was 90 degrees at midnight right here in North Carolina. I have to cover it with more than plastic and leave my heat on in the winter because though we in North Carolina have very mild winters respectively, when you consider you Montana, some of those north west kind of states, you talk Colorado out west, that kind of thing, it still gets cold.
Caleb Lawson (06:09):
It still was 34 degrees this morning so that if I just left the doors open and left the heat off, my concrete is not going to cure properly. So I have to pay more attention here. And y’all in environments that are very harsh and cold, need to pay more attention to how you’re choosing to cure your concrete. So it really is an active choice, not just to throw something over it. And yeah, so my point in all of that is basically the same point Jeff made is as a business owner in the act of running a business, we have to make choices. So I’ve heard a lot of people use the phrase sealer of the month club. And I think that’s an interesting exploration that maybe we’ll get into later. But the point is choosing different product to try and improve your business, but using that product in the business is never something I’m going to encourage. So try a new sealer by all means. Just don’t do it on the project. Try and make time on the weekend to roll, roll your sealer or spread or whatever you’re doing on some sort of santa piece.
Jeff Girard (07:21):
A can of worms that we don’t want to open right now.
Caleb Lawson (07:23):
But my point is,
Jeff Girard (07:25):
Don’t ever experiment on your customers
Caleb Lawson (07:28):
If you want to improve, if you want to change the game. So, but do it in a controlled environment where you can know what the results are going to be before you translate it to your clients. Yeah, that’s all I’m, and
Jeff Girard (07:41):
Caleb Lawson (07:42):
Not being into sealer or anything like that. I’m just saying we as this baby industry have a tendency to experiment on clients and I don’t love that.
Jeff Girard (07:53):
Very good point. Very good point. Something that I’ve seen over the last 20 something years, and we probably will see, still see for the next 20 years is the tendency to go rogue and to do your own thing. That’s pretty prevalent in this industry. A lot of people are very proud of the fact that they’re independent and that’s great and that’s kind of what makes this industry so special. But we have to remember that we as humans, our choices and our feelings don’t matter because we’re working with a material that doesn’t care about us. Our boss is the concrete, our boss, the concrete does what it does. And if we don’t handle it right, we don’t make it right. We don’t mix it properly, we don’t proportion it properly, we don’t hear it properly. It’s going to tell us, it’s going to scream and hit us over the head and it’s going to do it by crack or curling, doing something that we don’t want.
Jeff Girard (08:57):
And generally speaking, when we make a piece and it doesn’t do what we want, it’s expensive. And if you’re making a big project for a customer, maybe this is a big dining room table or maybe it’s a fireplace around or who knows what it is, it doesn’t matter. But if it’s pretty big and it doesn’t turn out and you have to do it again, not only does it cost you all that money because you have to do it again, but now your customer’s very unhappy and maybe your business takes a hidden reputation because now you haven’t met, you haven’t satisfied your promise to deliver something that they’re expecting. So there are very deep and profound implications to going counter to good practice. Curing is one of those good practices that is always preached. And I’m not just talking about in our field, and I spoke at World of Concrete for, I don’t know, 14, 15 years and with other speakers, curing is such an important part of our field.
Jeff Girard (10:05):
But so it’s done so lackadaisically in under most circumstances. And the only places where it’s really done with us any degree of control are in precast plants. Especially precast plants where they’re making a structural element that has to be, there’s a lot of liability tied to it. A bridge girder for instance, or something like that where the failure of that member, if it’s traced back to the people making it, that could be quite serious and we don’t have to worry about that. But the point is, curing is an extremely important part of making concrete. And the normal curing process of covering things in plastic and keeping it wet for a long time is simple and cheap in terms of materials, but expensive in terms of time. Nobody can afford to have a piece of concrete sit on their casting tables for a week and
Caleb Lawson (11:10):
Then don’t even get us started on ghosting. Cause I mean things,
Jeff Girard (11:13):
Right? Exactly. Because we are extremely sensitive to the visual variations in our concrete. The things that we can’t tolerate aren’t even a concept in the rest of the concrete world. So we’re extreme. We are on a very sharp, sharp, sharp, pointy end of the sensitivity scale. I mean we’re leading edge really. We are on the leading edge where two slab that have to be next to each other and one’s a half shade difference than the other that that’s perhaps a reject of the process of the whole project because things weren’t perfect. So we are on the bleeding edge because of the nature of the types of products and the types of customers we cater to.
Caleb Lawson (12:00):
So to tie it back together, cause we are a little bit above our typical 45 minute kind of deal, I want to respect the time of people listening, but to kind of tie it back all together is until such a time when the standard changes, it seems to me smart to at the very least do your own testing.
Jeff Girard (12:29):
And very few people who are in business who are running successful businesses have that kind of time. And so they are kind of left to trusting other people who advocate for certain practices. I’d like to think that some people trust me because not only am I an engineer, I’m a licensed professional engineer. So that means just like a doctor has to get a license, just like a lawyer has to get a license, I have to get a license. It’s
Caleb Lawson (12:58):
Jeff Girard (12:59):
That big thing right there. That’s my license. Okay? It’s not just a casual thing. It’s not just that I went to school and got spit out and one of those is my diploma. Both of those are my diplomas, bachelor’s, masters. That doesn’t mean anything. That means something right there that says
Caleb Lawson (13:17):
Path. Well I imagine like a doctor or a lawyer or whatever to maintain your license.
Jeff Girard (13:25):
I have to do continuous education. I have to self-teach year after year.
Caleb Lawson (13:30):
You have to
Jeff Girard (13:32):
Have to re-certify. And the whole point of that is I have learned from and draw from a very vast wealth of experience and knowledge that have been passed on for the last century or more scientists and engineers who find best practices and tease out the behavior of things and consolidate them into rules and guidelines and equations and codes so that ultimately folks can make concrete and that concrete does what they expect and what their customers need. The whole point. So I’m not just making this up in my garage and I don’t have an agenda to, that’s a personal agenda. It’s a conduit of all this knowledge based on my fellow engineers over the last century or so all over the world. So it’s not just me, it’s just not Jeff Girard saying what Jeff Gerard thinks. It’s I’m just the mouthpiece of this vast information into a world that I have deep roots in.
Jeff Girard (14:55):
I have deep experience. I’ve been doing this since 1999, longer than a lot of other people. And my observations, my personal experiences and certainly my experiences and interactions with the thousands of people I’ve taught over the years, tell me and give me insight that is very useful and helps me shape and tailor the kind of information that I know we all need. And this podcast is one of those needs is what is polymer and why do we use it? So kind of like you said to not to wrap this up, I’m not ending at this moment, but polymer’s there to help your concrete cure and curing your concrete properly is essential to getting the kind of performance you want out of your concrete. And if you make a piece of concrete and you don’t cure it properly, it’s not going to do what you expect.
Jeff Girard (15:52):
And so you might make a piece that’s a little bit different because maybe it was a dry day, maybe that piece was a little bit longer, maybe it was a little thinner, the design was different, something, right? But you are not aware of the differences or the significance of those differences and your practices of maybe doing it things a certain way have been successful in the past, but that one project revealed the weaknesses or the vulnerabilities of those practices and all of a sudden the piece didn’t do what you wanted. It snapped when you were installing. It broke when the customer used it curled or it cracked or it did something. And I’m not saying that’s always going to happen, but changing the rules because you don’t like them or somebody online told you you didn’t have to follow them. But those rules are inconvenient for you to follow tho. That’s not necessarily good practice for a business. And I’m going to kind of get on my soapbox and wave my finger and say, Jeff Girard says do good curing and polymer makes it easy to do to good curing. That’s what its job is for. It’s
Caleb Lawson (17:14):
Basically what you’re saying is if you don’t have polymer, you need to have something else that makes up that purpose.
Jeff Girard (17:18):
Excellent summary, excellent summary. And for a lot of folks that’s just not practical right now to circle back, we’re talking about Portland cement based concrete here because Portland cement is a mixture. That is an ingredient that’s very common. We almost all of us use it, most of us use it, but it’s a very slow process. It’s a slow chemical reaction. That’s why we talk about the 28 day strength because it takes about 28 days for that cement hydration to reach close to its ultimate, we’ll call it 90 degree, 90%. I’m going to wave my hands that are and generalize. I do one day tests on my concrete because I want to see what it’s like the day I flip it. I do one day tests, I do seven day tests, I do 28 day tests and I get a spectrum of how does it perform. Certainly when you take a piece out of concrete, out of the mold, it’s covered under plastic. It’s hasn’t really dried out yet. So there’s no real issues there. It’s w what happens to it in your shop after you take it out of plastic and you start doing stuff to it.
Jeff Girard (18:27):
The issue where curing polymer can really help things mitigate that, that moisture loss maintain those high curing rates, especially at the surface that we see, touch, feel, and gives the concrete its strength. And that’s kind of the root of this discussion. Now there are folks, I’m going to bring this up because I know about it. Some of us use Rapid Set Cementall, CSA Cement and CSA Cement has a chemistry, you do it, I do it. Some folks only use that. Now it’s chemistry is a little bit different from Portland cement in that it hydrates really fast. The whole matrix hydrates in hours, not days. So you literally can get 28 day strengths in 24 hours. And so its strength gain is faster than its drying rate. So technically you do not need a curing polymer in G C SSA cement. But I’ve found that it helps and it helps in the fact that when, because CSA cement reacts so fast, it gets hot.
Jeff Girard (19:48):
We’ve all seen this, it gets hot and it can get so hot that you would burn yourself if you touched it. 160 degrees is not that uncommon, especially for thicker sections. Now if your concrete’s hot and it’s uncovered because why would you cover concrete that you just finished casting? It’s going to start drying itself out. It’s going to literally cook itself, dry itself out, and then you might see cracking or discoloration in the concrete. And I found even just covering that with plastic isn’t always enough to prevent that in all circumstances. Now the practice is to, the way you get around that is you keep the concrete wet for the couple few hours it’s going through its thermal peak. So once it’s passes thermal peak, it’s not going to dry itself out and it’s strong enough that you can just leave it alone covered plastic and you’re done.
Jeff Girard (20:48):
Some people don’t use polymer at all and they get away with it. I’ve found that if you use polymer in that you don’t have to do the wedding and it makes it a whole lot easier to cast carbon plastic and walk away. So it’s less critical in CSA based cement because of the rapid strength gain because it’s giving you literally 28 day strengths in 24 hours. So three hours, you’re getting probably three four day strength in three, four hours after it gets hard. So again, it’s strength gain surpasses its drying rate except for the fact that it gets hot. If it gets hot and starts really cooking itself, then you can have some problems.
Caleb Lawson (21:34):
And so really cause this using a retarder like citric acid can lower that curve of
Jeff Girard (21:43):
Spreads out the heat so the slab can cool. And that’s definitely a way to mitigate it in and that’s the case. It’s a recommendation, but it’s not a necessity.
Caleb Lawson (21:57):
And so I think if you’re not going to use it in rapid set, you just need to be mindful yes. Of hearing practices and those caring practices are over five, six hours instead of a day. So maybe if you finish casting at 5:00 PM you need to stay around until six or seven and make sure that it’s properly covered and properly wet and things of that nature. And I’ve had to do that. Alternatively, you can put the polymer in it and make sure that you’ve dusted your harder properly and covered plastic and go home.
Jeff Girard (22:28):
And to reiterate, the polymer does not slow down the curing rate. It does not affect any, it’s there to hold the moisture in and that’s his sole job. Yes, acrylic polymers are very good adhesives, but we don’t have enough of that in the concrete to act as in adhesive. That’s why thinsets and micro topics and things like that have such a high polymer load to different kind of polymer that’s cheaper because you need high polymer loads to get good adhesive properties and good structural characteristics. We’re using it strictly as AC curing E element and only acrylic polymers of the right kind of acrylic polymer does do that hold a moisture in. That’s what they’re for. So in Portland cement-based concrete, when you’re casting something very thin like we mostly do, and you are on a quick timeline turnaround timeline of passing today, de molding tomorrow, do rapid processing sealing, getting it out the door. Maybe you get it out the door in a week. You cannot afford to be wet curing your pieces for a solid week before you even touch them. That’s just not practical. That’s why we use polymer.
Jeff Girard (23:54):
There you go. So it’s been a bit of a roundabout discussion and hopefully you’ve painted a better picture of why do we use polymer. And a lot of the discussion really didn’t talk about the polymers themselves because what they are is less important than what they do. And what they do is help cure your concrete. And that’s really the heart of this discussion is you’re your concrete properly so that you get what you expect. Because we work hard, we spend a lot of money, we spend a lot of time, our customers are depending on us to give us good products that are going to perform well, that are going to last a long time, that they’re going to be happy with. And the more people who do things well, and the more customers who are happy, the more this industry and your success is going to grow. Yep, exactly. So with that, I’m going to sign off. Caleb’s going to sign off. Thanks for joining us. Take care. All right, we’ll see you. Yeah. Bye-bye.