EP #118: Concrete Petrography Explained

Seth Tandett (00:00)
Welcome to another episode of Concrete Logic Podcast. And today I have Dr. Jon Belkowitz back on the show today. Always a good time to talk to Dr. Jon. So today we're going to talk about what petrography is and what can it tell us. normally, in my experience, petrography is used to when the

Crap hits the fan. So when a concrete doesn't come up to strength, they're checking maybe concrete was placed that shouldn't have been placed in a certain area. So they want to check out what it is. So Dr. Jon's going to explain what it is. But it's a pretty powerful tool. It helps us diagnose failures, improve mix designs. And it's

I think everyone should know what it is if you have concrete on your project, which every job has concrete on their project. with that, Dr. Jon you could define what petrography is and how it's used in concrete.

Dr Jon (00:51)
with that. Well,

So funny enough, I talked to my dad about this podcast since we missed it last week.

And he said, you know, it's always good to start with not only a definition, but your closing remarks, what you hope people can learn. So I wanted to define the word, patrography first, using the Latin, then the Federal Highway Association, and then I wanted to give you my closing remarks, all of which should take about two minutes to do. And then from there, go on to what your thoughts are. Does that sound fair?

Seth Tandett (01:26)
That's great. Thank you.

Dr Jon (01:27)
So petrography comes from two root words or two words, Latin words. One is actually petra in, you know, United States and America, we use petro for petroleum based products. But in Latin, petra stood for stone or rock and graphy is the study of. So petrography is the study of stone and rock. Now.

if we go back to the Latin. Now, if we go to the Federal Highway Association, back in 2006, they have this wonderful publication that's all about the historical background of analyzing concrete. And they define...

Petrography as a branch of science of petrology, which in addition to description classification includes the deciphering of the origins of rocks, study the relationships between various rocks, mineral deposits, study of the effectiveness of various geologic processes and unveiling the complex history of rocks. It's a very nice, well authored sentence there. And they go into the different tools and techniques

which we'll be talking about today, which is petrographic analysis is a powerful tool for understanding and solving concrete durability challenges. I think that's the first thing that you brought up, correct?

Seth Tandett (02:43)
Correct.

Dr Jon (02:44)
But then it's not just about identifying the problems, but it's also enabling the civil engineer, the ready mix producer to create a better concrete mix design for value added and long-term performance. So I think you had brought up ASR or calcium oxychloride formation. It's not just about how we're solving problems that

already happened being, what's the word, reactive but being proactive. And that's what I hope to get across to your audience today.

definition, what it is, and then where you would use it.

Seth Tandett (03:20)
Yeah, how does it actually apply to concrete and what kind of information can we get? Explain the process first. Let's explain the process of how you use... What? Yeah.

Dr Jon (03:28)
Okay, so we have

two situations, right? We've got somebody who wants to be reactive, which you already talked about, and proactive. So we're gonna start reactive first. Let me get a pencil here so I can write some notes and just keep track. So let's say you are, so this is reactive. You own a hospital or you're a contractor who builds hospitals, right? Contractor for hospitals.

and you get a call from one of the attendees on the floor, one of the floor maintenance guys that you've got some rubber flooring, dimpling. And when you come down to your floor, there's these big old bubbles where all the beds turn, right? What you would do as the contractor is go take some pictures.

and call a concrete testing lab to come in because this is a common problem. Say, hey, what the hell is going on? Why is this falling apart? Now, you might also call the flooring provider and say, hey, what the hell is wrong with your tiles? But let's leave it out of it. Let's leave the litigation side out of it. So what you would do is you would call a civil engineering firm and have them come out.

And whether or not they have that skill set, what they're going to want to do is investigate what the hell is going on and why is the concrete doing that. Because putting rubber or vinyl or even asbestos tiles, which we don't do anymore on top of concrete, is not a new thing.

And normally if we keep our concrete within a certain amount of conditions, whether it's relative humidity or all of the suggestions that Bob Higgins has, there's a boundary condition that if you stay under the moisture content, the salt content, you can have your adhesive and your tile or your coating stay on for a very long time without it delaminating, tenting, bubbling, the adhesive not working.

So what they normally do is, either with or without the tile, they're core through the concrete and they'll take samples. Right? So what a petrographer does is, where they get a big old cylinder, they'll take slices of it from the top.

from the middle, from the lower section, all the way through from the top surface of the concrete throughout the body to the bottom to investigate. Now normally, and again this is all dependent on who you're working with, if this is a flooring provider, they don't go deeper than that top surface subsurface. What they're looking for is what is on the surface and they might do some chemical analysis.

Seth Tandett (05:48)
Right, first inch.

Dr Jon (05:54)
They might go subsurface to see, is there finishing issues? Did we not have a CSP, a concrete surface profile? Do they not prepare the concrete? And then they can also look for holes, pores, any irregularities that's in the concrete that would be indicative of what would cause the failure.

Now, what Bob brought up is what we're seeing in a lot of these floors is that if we do some type of chemical analysis, which you you have in your ASTMC 856, you see I use this thing all the freaking time. This is like the third copy I've got. But it goes over the different techniques that you've got to use to identify what the heck is going on with your concrete. And some of those techniques are examining the chemistry.

So for let's say a flooring issue, Bob brought up salts. If we have somebody do petrographic analysis with let's say, I don't know if they're using x-ray diffraction, gas chromatography, x-ray fluorescence, there's so many different types of techniques, but what we're doing is looking for a mass species. So you have, when you make concrete, even if your concrete bleeds, you have a certain amount of sodium, calcium, potassium, magnesium, blah, blah.

say, where did put my concrete? They're evaluating the top surface that was meant for rubber tiles and there's eight to ten times the amount of sodium and potassium at the surface. What would Bob tell you? Would that floor be successful or unsuccessful?

Seth Tandett (07:19)
That's a failure, but how do you know that?

Dr Jon (07:21)
Well, they do, that's what I said, they take the sample, take a little bit off the sample, or they can put in a scanning electron microscope and they look at it with a specific set of electrons that go at it, and those electrons bounce back, and with that, we have references that say if electron bounces this direction, it's this type of mass species.

Seth Tandett (07:31)
okay.

So there's a special microscope that you use for this. I can't go buy one at the store and look at my concrete.

Dr Jon (07:45)
you can if you want. It's a very special

store, but no, there's a bunch of different microscopes, gas chromatography. There's all this different equipment out there that we have at our fingertips to use. Some of us have all of them. You know, I don't have an SEM. I want an SEM. I work with people who have SEMs, so I get to use them all the time, but I don't have a tabletop SEM. I already tried to convince Whitney of that one, and that was back in like the early 2000s.

didn't work. you know the microscope. Sure sure sure. So that's under ASTMC 1723. It's a scanning electron microscope. So scanning electron microscopes are pretty f-ing cool. Just the concept of them.

Seth Tandett (08:14)
Yeah. What's a SEM before you

Dr Jon (08:30)
When we use a regular optical microscope, when we either have light shining down on our sample or light shining through our sample, what we're looking at is a shiny sample because we're lighting it up. Well, a scanning electron microscope is, okay, you're still there. A scanning electron microscope is something that's similar in that we are projecting an energy source onto our sample, right? But,

Seth Tandett (08:46)
I'm still here.

Dr Jon (08:56)
we're using not a radiant light, we're using an electron source. So the light particles or the energy particles are a thousand times smaller, if not even smaller than the waves that we're getting from our light bulb.

Right? Right? So we're in this vacuum chamber, we got a piece of our concrete, and we're looking at not the concrete itself, what happens is the electrons that we project at the sample, they hit the atoms of the mass species of the calcium, silica, all the different shit in there, then they bounce off the sample, or excuse me, they hit the mass species, then an electron is

Seth Tandett (09:11)
cool.

Dr Jon (09:38)
projected off the sample. That electron that is bounced off the sample is called a secondary electron. We catch that on a screen and we turn that into a 3D image. Do you want me to show you one real quick? So here, maybe I can show you a lot of them real quick.

Seth Tandett (09:50)
Ooh, that's cool.

Yeah, that'd be great.

So while you're doing that, this is a specialty thing, so only certain folks can do this.

Dr Jon (10:06)
Hey, listen, if you want to go get a degree in this, if you want to spend your time as a hobbyist and working with, different universities, you could do it as much as you want. That's how I started doing this is just, I kept asking people, I was like, Hey, can I use your scope or can I try it out? And you know, you ask enough people, you annoy them enough. They eventually say no, or they eventually say yes. so this is, can you see my screen?

Seth Tandett (10:32)
Yeah, that's cool.

Dr Jon (10:33)
So this is from the work I did. So I've done a lot of training and that's one of the biggest things you need to be a photographer, whether it's...

scanning electron microscopy or you we've got our other microscopes over here. I think one goes up to 150x and the other one goes up to 1800x. This one is going to 1000 and I think we have a few images that go up to 20,000x or 200,000x. But what we're seeing here is you talked about it before, ASR. So this is the ASR gel rosette under a high powered microscope.

So you're not looking at inches, our scale bar over here on the right is microns. So it's a hundred microns and this is just, I mean, there's a lot of scientific value as we get deeper or a higher magnification. But just looking at it, it's a very beautiful image. Oops. So this is...

Let's see if I got any, so that's all 1000. You still seeing this? So this is 2000 mag.

Seth Tandett (11:36)
Yes.

Dr Jon (11:39)
And now you can see we're going a little bit deeper into the individual microstructure. Instead of seeing the big gel itself, we're going into the lathe-like or wispy-like fibers that make up the ASR gel. Now, the reason why we care about that is because that fiber-like morphology, the way that the different, you know, for lack of a better term, the gels collide or the way they stack up against each other or the crystals,

creates a morphology that draws in not only more salt but water. Now if we can use a certain chemical to change the morphology of that, like let's say nano silica, we can change the mechanism of how that water is drawn into the ASR gel and how that ASR gel can thrive and survive. Does that make sense?

Seth Tandett (12:27)
Yeah.

Yeah.

Dr Jon (12:28)
So that's a zoomed in. Man, it doesn't let me.

They're just so beautiful.

Seth Tandett (12:34)
And it just looks like a bunch of different textures. Is that just different samples or is that just looking at it?

Dr Jon (12:39)
Well yeah.

So different samples, so all these different looks to them is the ASR gel with different types of nano silica or without nano silica. So the more feathery like or the more fuzzy like like this, so this is a 30X, 30,000X, excuse me. So this is looking at the different fibrils of the gel and this is the reference. So this is without nano silica.

And this is what I was talking about, these things line up against each other, they create extremely small pores, and with that you get this capillary pressure, this pore water suction that drives water into the ASR gel so it can create more of the expansive gel with salt.

isn't that beautiful?

Seth Tandett (13:33)
That's crazy.

Dr Jon (13:34)
Yeah, so the more of the nanosilica we bring to the environment, the more of this that we have.

where we lose that wispy-like, have less of these smaller pores, we have a lot more bigger open pores, so we reduce that capacity for capillary suction, that drawing in of water into the ASR gel. But this is getting into a really specific type for a very specific project. Do you mind if we go back to the failure shtick?

So I just want to finish that up. So what we can use is for, let's say a failure of floors, is that top surface to see, did the contractor put anything on it weird? Did somebody not do a good prep? Was there a lot of moisture on the floor? Is there hydrolysis going on?

It's a, I hate to use post-mortem because that often refers to a person's death, but it's after failure and it could be anything. We're using it on bridges to see how well bridges are doing, you know, a year and a half into their service life. I was just part of a study that's looking at how cement composition has changed in terms of being consolidated for pavements.

And what we're seeing is a segregation of the aggregate from the top surface down through the bottom surface. And you have more of a paste here, which is more susceptible to that early failure, whether it's abrasive wear or plastic or drawing shrinkage.

So that's another failure scenario that we can look at. And you could use everything from the low magnification microscopes to the high magnification microscopes that we just looked at here a second ago and get similar images. I don't know if you can say that, but it's images that help you tell a story. And that's what you try to, it's a story problem. We have a problem here. How the hell did it happen?

Now what we're trying to figure out is we're trying to find clues to help us identify what went wrong. Are we always going to find that? That's the problem that you might not always either have a photographer who's good enough. The tools that they have might suck or they're reading the tea leaves the wrong way. That's why you've got to go through a lot of training because...

There are, it's almost like being a medical doctor in that it's never a singular thing when concrete fails. There's normally a coupling event, two things go wrong, or multiple things go wrong at a time.

Like for instance, if we're talking about flooring, it's rarely that it was just a moisture related issue. That's again, I hate to keep going back to Bob Higgins, but that had to have been your best podcast to date. hasn't stopped, Daniel hasn't stopped talking about it and he sends it to people and he tells them it's required listening. Yeah. I'd love to see the numbers on that one, but anyway.

Seth Tandett (16:15)
Well, that's good. Good.

Dr Jon (16:20)
This something that Bob talked about. He's like, rarely is it a singular event. Rarely is there some moisture. And don't tell me that because I have a relative humidity of 85%, I'm going to be okay. Because if you got a lot of salt at that surface, there's going to be a gradient. There's going to be a moisture draw, whether it's from the ambient environment, if you cut your concrete open or it's still open, or...

If somehow, I know he doesn't believe in it, and somehow you get some type of negative pressure from a moisture head underneath the concrete. I agree with him that that is rare at best, but that still does happen, especially if you've got places in Arizona where you've got geysers coming out of your joints. So.

That's one way of using petrography to identify, you know, hey, it's not just the relative humidity using this analysis technique like, you know, scanning electron microscopy or the different XRDs fluorescent get the different chemical identification techniques to see, hey, there was a urethane still at the surface. There was some fatty esters. Something that shouldn't have been on the surface was there.

Right? It wasn't just the flooring thing. It wasn't just the adhesive, you know, not being designed correctly or somebody didn't choose the right one. We chose the right one. Just somebody did a something wrong to the surface. Now it could also go the opposite way. Hey, there was nothing wrong with the surface. Perfect CSP. There was no relative humidity. There was no slots at the surface. Somebody just didn't use the right adhesive or the right amount of the adhesive or they didn't use it the right way. Now.

Seth Tandett (17:33)
Right.

Dr Jon (17:47)
That's being reactive, being proactive. Can we go there?

Seth Tandett (17:49)
Reactive, yep.

Yep, that was gonna ask that.

Dr Jon (17:53)
So two people are proactive in the industry, the people who produce concrete and need to know what the heck my materials are gonna do to the concrete, whether it's alkalized silica reactivity or it's pyrotide attack.

Some could even argue that the chemical technique that Dr. Weiss came up with when he was at Purdue for calcium oxychloride formation is another technique and all that goes to supporting concrete mix design and hey, can we use this material? So there is a specific ASTM for petrographic techniques for aggregate and I believe it's ASTM C295. I'd love to tell you but they packed my book.

Pack my book. We're not moving for another six months.

Seth Tandett (18:36)
So they ask you to do petrographic effort on stuff they're testing in the yard or.

Dr Jon (18:44)
No, no, no. So if I'm the aggregate provider.

Seth Tandett (18:47)
Yeah.

Dr Jon (18:47)
I need to get, I can't remember how often it is, whether it's a year, six months, but they've got to get a petrographic analysis of their aggregate to look at the mineralogy. And basically it's what you were alluding to before. A certain aggregate or alkali aggregate reactivity is one of the things. And that's what you're looking at. What you do is you take the rock and you're looking at the quality of that by taking these very thin samples.

What are they? 30 microns thick. And you're putting under a certain polarized light. And from there what you can see is these beautiful diffraction patterns of the rock. Now, you know, there's certain mineralogies like mica. I think you've seen mica before. That has a certain look to it under light. Now, if you look at certain patterns of rock that were getting out of this lift, and it shows a very distinct pattern for rocks that are

susceptible to alkali aggregate reactivity, then either we have to design that in the mix or that rock becomes, you know, riprap or fricking, you know, landscaping material.

Seth Tandett (19:51)
okay.

Dr Jon (19:51)
Yeah,

depends. Now, folks do the same thing with cement where they do not only chemical, they should be doing a chemical analysis every month or every so many tons, which is just using an XRD, an X-ray diffraction, where you're looking at chemical composition saying, I want to know how much of my tricalcium and dicalcium and silicates are in my cement, my A-lites or B-lites.

And not only did we use x-ray D, but we also used microscopy to look at that too. The A lights and the B lights have a different look to them, where the tricalcium silicate, or I believe that's the A lights, have a more of a, what is it, hexagonal shape, face cubic centered, so they're more angular. And you see much more of it. You normally have like 60 to, or was it 50 to 70 % tricalcium silicate.

what makes up your cement, but then you have your dicalcium silicate or your C2S or your B-lite, which is more rounded, it's more embedded in your tricalcium silicate, and we find less of it.

Seth Tandett (20:52)
Do they do this at the at the point of just clinker or after the grind?

So could you talk about a of a case study of when someone reached out to you for this?

Dr Jon (21:03)
you know, most of our case studies are on litigation.

Seth Tandett (21:07)
well, I know I was hoping you would say I have a proactive client that we just talked about because that's one of the misconceptions that I had was this petrography at least on in concrete is only used as a crap, we got a problem. But what you're telling what I learned today was no, there's actually people that ask for this analysis because they're being proactive because they want to know what material they're

they're working with. So that's good to hear. you have something like that you can share or is it? Okay.

Dr Jon (21:32)
Right, so.

I do.

Now I can go two different roads. I have something that we can look at that I did on ASR gels specifically, something that we already looked at with nano silica or something that I think this is better where we did a whole bunch of different type of analysis techniques as part of our petrographic analysis.

Seth Tandett (21:40)
Okay.

Okay.

Let's do the better one, the last one.

Dr Jon (22:02)
Okay,

so let's do the better one, let's do the last one. Hey, thanks for catching me on that, you two. I really do appreciate that.

Seth Tandett (22:09)
to keep us all out of trouble.

Dr Jon (22:10)
It's not us that were doing it. Is that in the weird light? Does that look pink to you?

Seth Tandett (22:14)
No,

no, I can see it.

Dr Jon (22:16)
Okay, so this was something I want to thank the taxpayer, the American taxpayer and the US Army Corps of Engineers for paying for my research.

Okay, so they did a great job of not only forcing me to stick to gray concrete coming down the chute, like Jon, if this is not helping out the industry, if this is research for the sake of research, then we're wasting time and assets. So this had to be something that could be used in the field. So part of my research was looking at not just the microscopic, but connecting the field, macroscopic,

to the microscopic and then going even a little bit further and that was into the nanoscopic. So that's what this whole question is. What is the impact of nanosilica size and surface area on phase development, degree of hydration and pore development? Now what we're doing here is we're looking at four different techniques.

Now, this was not something that we did after the fact. This is something that we did before anybody understood what the hell NanoSilica was on the ReadyMix site. They didn't know good or bad, and we wanted to look at it with open eyes and big bellies, the good as well as the bad. Almost wanted to make it like a product brochure or have a troubleshooting guide as well as try this for your next job site. Does that make sense before I go on?

Seth Tandett (23:42)
Yes.

Dr Jon (23:43)
So we got four techniques here. TGA, which is thermal gravimetric analysis, where we're taking our hydrated sample, Portland cement, water.

We crush it up after 28 days into a fine powder. We put it into our thermogravimetric analysis. We heat it. We either catch the stuff that's coming off or we measure the change in weight and we differentiate that change in weight over time. It tells us a certain what was in the sample at those temperatures. Was there a lot of calcium hydroxide? Was there a little bit of calcium hydroxide? Calcium silicate hydrate, water content.

so on and so forth. With NMR, nuclear magnetic resonance, that's kind of like putting your concrete into an MRI, where we're subjecting our sample to a magnetic field, and then when bombarding it with radio frequencies, the silicas bounce out of that radio field or that magnetic field.

and then they go back to their original field. Now that relaxation time tells you at what state the silicone is within our hydrated cementitious composite. Now you combine that with scanning electron microscopy, which helps us look at the topography, some of what we looked at before of our sample at a microscopic scale with...

backscattered electron microscopy, helps us look at pore structure as well as phase development as well as chemical analysis, we can come up with an overall story which goes back to our question, what the heck is our, not just our nano silica size, but the surface area doing to our hydrating cement? And the reason why I say that is, or ask that question in the beginning,

We didn't know that there was a difference between using a five nanometer particle and a hundred nanometer particle. We kind of closed our eyes, threw it in the back of the truck and hoped something good was gonna happen. But as we make our particles smaller, that specific surface area is gonna have a lot more changes to it, reactivity, dissolution rates, on and so forth, as opposed to the larger particles. And that's what this was all about.

So calcium or thermogravimetric analysis, one of the things that it's been used at for a long period of time is looking at not only the calcium hydroxide content, but it's a backwards way of determining if you have...

reduce the amount of calcium silicate hydrate content in your mix. And what we get out of it from the nano silica is that.

There you know from what we found is chemically speaking the smaller we go in particle the more calcium hydroxide we consume and we assume that from the consumption of our pozzolanic reaction to create more of our calcium silicate hydrate so from this information nano silica one Over here in blue was our smallest particle three to five nanometers then we had 15 to set or excuse me nine to eleven

nanometers and then here was 45 to 47 that nano silica 3 and in the front our black and orange were our references or straight cement and our 20 % class of fly ash and what we found and I believe this is at 28 days is that using nano silica we can have a direct impact on reducing calcium hydroxide content just as we would with our 20 % class of fly ash, but

we're doing it with a significantly lower amount of material. Now, besides using the TGA, we wanted to use another method, and that was that nuclear magnetic resonance. And what the NMR is looking at is the calcium silicate hydrate structure itself. And if you've never looked at a calcium silicate hydrate, I don't know, have you ever looked at one under a microscope?

Seth Tandett (27:38)
No, I'm a practitioner, man. I just put concrete.

Dr Jon (27:42)
I don't know, so am I, but I read this shit

on the weekends. It looks like a ham and cheese sandwich. Right, so you have the top portion, let me see if I can do a laser pointer. You have the top, you see this laser pointer? So the top portion over here is your bread, that's the calcium oxide layers.

Seth Tandett (27:47)
Yeah.

Dr Jon (27:59)
And this is after all the hydration is happening. This is looking at the calcium silicate hydrate, the backbone of concrete strength. Then in between those pieces of bread, you got your ham and cheese. You got these interlayer dominated silicate chains with water and calcium ions. We call those bridging silicone tetrahedron. And on top of the sandwich, we've got these pairing silicone tetrahedron. Now what we want to do is condense the interlayer

layer

dominated silicone tetrahedron. Now, one of the easiest ways for us to see that is using this NMR. And what we're doing is we're trying to increase not only the number of silicone states within this ham and cheese or within the sandwich, but we're also trying to increase the density. So we go from Q0, Q1, Q2 to these Q3 states.

So when we put in more of our nano silica, what we're finding is we're changing up the state, and that's what all these numbers represent. The top portion is our controls, where we have none of the Q3 states. And then once we start adding our nano silica,

we start increasing our Q3 states as well as our Q2 states. We're densifying our calcium silicate hydrate, which is great for us because a denser calcium silicate hydrate means that we're creating something that's less susceptible to alkalized silica reactivity because it's imbibing, it's controlling, it's chemically binding those alkalis, that poor water solution that would contribute to that alkalized silica reactivity.

surviving and So then what we do is we go to another test where we look at the phase development, that this is backscatter electron microscopy. And what we're looking at here is a flat polished sample of our nano silica or our cement paste only without nano silica here on the left.

Here it's with too much nano silica, the smallest nano silica at a very high dosage, and then a much larger nano silica at the same dosage at the smaller one. And what we see from this is that first too much of a small nano silica is not a good thing, but we use an image or a gray

I'm sorry, a grade point counting software called ImageJ to do a surface analysis to tell us how much of the calcium hydroxide we have left over, how many pores, how much unreacted cement, and how much of the calcium silicate hydrate we have. And it's just a point counting system based on the gray scale of what we're looking at under the microscope. But then we come back, or first we do, I'm sorry, a chemical analysis

to evaluate what color it is that we're looking at. So for instance, if you're looking at this one, this is without any nano silica, you see a lot of light gray and dark gray in here. Then when you get to too much nano silica, you see all that black stuff.

That's all the pores and whatnot, right? All the holes. I think that's easy for us to understand. The light ray stuff is unreacted cement. We call that anhydrous cement. Now the reason why it's light gray, it's getting brighter. It has some things in it that will hold onto electrons. It'll start charging.

If there isn't anything in that space, won't hold onto electrons, it won't charge, and all we'll see is black, hence we have the pores. Now what we do is we take this sample, we zoom in on it, and then we use the backscatter electron microscope. It has something called an energy dispersive x-ray analysis tool, which allows us to collect some of those electrons and identify what we're actually looking at, either using a line method,

or an averaging method or a point method.

Okay.

So this is something a little bit different. We didn't use this in our research, but this is transmission electron microscopy. We're looking at it at almost like a molecular level. So this is the calcium silicate hydrate under a much higher magnification. And we're going down to those individual ham and cheese layers here, which is a lot higher magnification than I've ever done. I really wanna use this type of microscope, but Whitney won't buy one from me.

Now, what it is freaking and you've got getting vacuums and special rooms for it. There have to be a certain humidity. So this was done by a guy named IG Richardson. Some of his work is, you know, just on the calcium silicate hydrate. He's got a paper on like CSH1, CSH2. What we're looking at here is this interfacial zone between on the right side, we have a very porous

Seth Tandett (32:32)
sounds expensive.

Dr Jon (32:57)
outer product of our calcium silicate hydrate. It develops very, very quickly, but it doesn't offer a lot of long-term strength because of the porosity of it. On the left-hand side, we have this inner product or this globular morphology of our calcium silicate hydrate. A lot denser, a lot stronger, and because of that, it's going to add to our durability. We want more of this on the left and less of this on the right.

Now the stuff here on the left, the better stuff with the happy face, it has higher orders of the calcium silicate hydrate, that Q2 and Q3. The stuff on the right, the bad stuff, the bad calcium silicate hydrate of the outer product has a lot more of the Q1 and the Q2 states and has almost none of the Q3 states. Does that make sense?

Seth Tandett (33:49)
I think we got to a point where it's over my head, but I generally understand what you're saying and why it's being used. So I guess just to sum up this proactive approach, this sounded like you were doing some research on nano silica and you were looking at different cases of how much, just as layman terms, so don't shoot me, Jon, is

Dr Jon (33:58)
Right on.

No, no, no, you're great.

You're doing freaking great,

Seth Tandett (34:17)
So

you were looking at, under this microscope, were different amounts of nanosilica on, is that correct? Yep.

Dr Jon (34:28)
Right, right, right. So,

yeah, so we were looking at, here we go. So each one of these, where it says CS1, CS2, those are three different distributions of nanosilica. And we looked at them in different samples at different dosage rates.

Seth Tandett (34:37)
Yep.

Yep. Yep. Understand.

Dr Jon (34:49)
And then

what we did is, like you said, that proactive, what the heck is this doing to just cement hydration, not concrete, but just to the cement, chemically speaking. And you can't just use one experiment, right? You can't just look at one magnification and you can't just look at one sample.

You've got it. There has to be ad nauseum. There has to be a plus or minus. There has to be a standard deviation because if you do this the wrong way, you can get erroneous results, results that really have no meaning to them. So again, it comes with, if you're not using enough experiments to look at it from all different sides, like when you go to a job site, you don't just look at it from the street, right? Right? When you're proactive,

Seth Tandett (35:35)
Yeah.

Dr Jon (35:35)
go onto the job site, you look at the excavation, you grab the soil, you get the soil tested, right? You see where the water table is, you identify what the structure is and when the maximum loads are. From there, you can understand how you build your foundation. Does that all make sense? We're taking the same principles here and we're using it, but instead of looking at it in a macroscopic, we're looking at it in a microscopic view.

Okay.

Seth Tandett (35:58)
So

I think we covered, there were several things I wanted to cover. was explain what petrography was, we did that. Two was when is it used? We covered that. And three was what are some misconceptions of it? And we learned that people actually ask for your services.

on a proactive basis, which I always thought was reactive. So I guess, could you share like, how much does this cost? Like if someone's like, I got, let's go back to a practitioner situation. This is, we're in a bind. Something happened at the job site.

Dr Jon (36:33)
Yeah.

Let's say you've got concrete tiles. You make concrete roofing tiles for a living. Right? You make two million a year and you sell them for multimillion dollar homes. Right? This is a real occurrence now.

Seth Tandett (36:40)
Mmm, yeah, that guy.

Yep.

Dr Jon (36:53)
What you would do is you would notice discoloration. And you would notice it because you would get some calls and complaints. What do you mean discoloration? You would get call after call after call. That's what the practitioner, whether it's the contractor that places them or the person who makes them and contracts them as well. They get a phone call from their owners, hey, I don't know why, but I got white lines, white streaks.

We're cleaning them and then well acid etch them. They keep calling you getting from mold So now what you do is you go out and you collect some of these panels and you're standing over them. You're like What the heck do I do

Seth Tandett (37:25)
Uh-huh.

Dr Jon (37:25)
Well, you didn't design them first. You probably called an engineer. So you're to call back an engineer and say, hey, I've got these concrete tiles, which people do. And I don't know why they're changing colors. I've been doing this for 20 years, and I've never had a problem with this. This has just happened within the last year. So we'll collect some questions. But then the question is, how much is it worth to them to do the petrography?

If this is a multi-million dollar deal, they should probably be contacting their insurance company and their insurance company will go through the same histrionics that we just talked about, but then they'll look in the yellow pages for a patographer, they'll interview them, and then they'll hire them, and that's how we'll work with our client.

If our client doesn't have insurance or they don't want to go through their insurance company, they'll ask us, how much is this going to cost? And to turn on any one of these machines, and I know this is going to sound crazy, but you're talking $100 to $500 just to turn on the machine. And that's just to turn on the machine. That's an hour,

Seth Tandett (38:22)
Yep. That's not as bad as I thought you were going to say.

Right?

Dr Jon (38:28)
So $100 to $500 an hour. So you're turning it on every hour after that. And that's just the machine. We're not talking about the photographer. And then the machine, that's only maybe 15 minutes to maybe three hours worth of work. The real nasty works comes in processing the sample. So you can look at anywhere between $1,500 to $6,000 per sample.

And then there, it's anywhere between 15 and 20 % of the total working cost is your report cost. It's not an inexpensive endeavor, to say the least. But let's say we're going back to this roofing tile. Well, let's say the guy's like, listen, I don't want to go insurance route. I just want to know what happens. So either I can talk to

you know, the folks that design this or maybe my raw material providers and see if I can stop doing this, stop this from happening. You know, that's, that's reactive, but that's a proactive direction that I know I can't sue anybody. can't go to an insurance company. I'm just losing out of pocket. I still have a business to run. How do I

You know, if I know what's going on, I know how to fix it. Let's say for the roof tiles, if they're doing, what's it called? Precast concrete roof tiles that they're doing in a form. It's a three cubic yard mixer that spits out an SCC. And we're noticing telltale signs of, you know, overdosing of the high range water reducer, whether it's waxy bubbly look on the top surface or it's

an excessive amount of bleed channels that are created that are going from the bottom of the form to the top of the form and then from there we're seeing the salts migrate to the surface too. Like that can be changed with something as easy as a mix design. Now, okay so what did that take us I think is what you are asking. Figuring that out could have cost somewhere around fifteen thousand to twenty five thousand dollars.

Now there are some photographers that will promise you, I need to take one look. It'll take me a few minutes, $1,000 under my scope.

For something that bad, where you're getting that many tiles, which is normally, you know, if they're doing like a two foot by three foot tile that's two inches thick, you're talking more than one batch of materials, especially if it's one million tiles. So cement has changed, aggregate may have changed. Definitely the personnel involved. So you're trying to find a common thread within all these different batches, which is a very hard thing to do.

and it takes a lot of samples and a lot of comparing and analysis and sometimes it's just looking at the same image over and over and over again to see what the details were.

Seth Tandett (41:03)
Yep.

Dr Jon (41:03)
or the difference in the details, excuse me. So that's very expensive. Yeah, I try to steer clients away from petrography as much as I can. I know that sounds funny because I'm in the petrography business and people ask, know, why? And it's because sometimes it might be the exact cost of

Seth Tandett (41:07)
Yeah.

Dr Jon (41:23)
you know, replacing or repairing, or it might be more expensive. Like you don't want to go to petrography unless you have to. And then the reason why, so, you know, I've been training for the better part of what I started in 2007. So what is it? 20, 19, 18 years that I've been trained to be a photographer and

All the folks that trained me, they were set to retire in 2018. Like it's 2025. some of the best ones are gone. Like my favorite photographers, if they haven't retired, they're about a year to two years away. So that was our biggest problem. We couldn't find a good photographer.

The photographers that we were using, just couldn't get their work complete on time. They didn't understand what they were looking at. They were jumping to conclusions. I I hate to say it, but unless you're doing an image counting technique and area fraction analysis, some of this stuff is very subjective. It's which one of these is not like the others. And that can change from person to person in technique and how good they are.

So, petrography is not inexpensive. The practitioners should know that if they're getting into it, if they need it, better be a damn good reason. I wouldn't just do it for the sake of doing petrography. Aggregate providers, they need to do it. That's ASTMC 295, whatever the hell it is. But there are rare occurrences where you really need to do it. Ugh.

Yeah, now, hey, if you can work with a university, you've got somebody who's training, they're just learning how to do it, you're not gonna get great results, but you can get it at a cost. And that's what I used to do when I was at University of Denver, especially for like metallurgical stuff. Like I was just taking pictures, I wasn't analyzing them, but I still got practice time, scope time.

Seth Tandett (43:05)
Yeah. Well, good. I think we got it all covered today. For sure. So if you wanted to learn more about petrography, you want to reach out to Dr. Jon, I'll put all of his contact information in the show notes. So please make sure you check out the show notes. And...

Dr Jon (43:09)
Awesome.

I tell you, there's, wait a second, there's some photographers that I'm a huge fan of. Do you mind if I call out some names that are just as good? I mean, they're amazing. And if we're ever stacked and racked on lines and we don't have time to do your work, do you mind if I just call out some names? There's Hugh Ho from WJE. He is top of the food chain. Like the stories that that man could tell. I'm a huge fan of him. Paul Stutzman, legend.

Seth Tandett (43:34)
Sure. Yeah.

Yeah.

Dr Jon (43:45)
in the industry. you've never read any of Paul Stutzman's works, they're all available at NIST for free, which is a government agency. And some of my earliest training was done under Paul Stutzman at NIST in Gaithersburg, Maryland. Then you have like the freaking, he's like, you know, what's that, that movie with Keanu Reeves and Patrick Swayze?

Point Break. Yeah, he's like Patrick Swayze's character in Point Break, but for petrographic analysis. David Rothstein. Yeah, yeah, he wears a shark tooth. Like he is one of the best petrographers.

Seth Tandett (44:04)
Point break, yeah.

He jumps out of airplanes. Wow. Nice.

Dr Jon (44:18)
And one of the coolest cats, I mean, was the motivation for me to start looking at my PhD. Had a beautiful facility up in Boulder, Colorado. was just three people. Him, young lady or a wonderful lady who worked behind the counter and the guy who did all of his prep work. And he, believe, sold to Twining and Company. I believe he retired too. But those three, definitely my top three favorite.

photographers and if I'm forgetting anybody like St. Paul or Darwin I just didn't work with them enough there's Daniel Armintrout who I worked with for my different degrees there's Frank Fisher I mean a lot but they aren't into concrete those top three guys if you guys ever need concrete work one more Brian Wolf from SGS TEC SGS another amazing photographer so I mean that's four

for photographers and I can't really name others that I think.

There's just not many out there. also recognize that as a practitioner is just there are slim pickings. So there are enough really bad ones out there, but the good ones are really hard to find.

Seth Tandett (45:14)
Yeah.

Yeah, well, I think you were saying it's expensive, but to me it's all relative. What's at stake?

Dr Jon (45:28)
Right, and that's what you have to keep in mind.

Seth Tandett (45:30)
Yep. All right, Dr. Jon, thank you. You spent a lot of time with me today. Appreciate it. And folks, until next time, let's keep it concrete.