Kim Swanson: 0:03

Welcome to AASHTO Resource Q&A. We're taking time to discuss construction materials, testing and inspection with people in the know. From exploring testing problems and solutions to laboratory best practices and quality management, we're covering topics important to you.

Brian Johnson: 0:19

Welcome to AASHTO Resource Q&A. I am Brian Johnson, with me is my co-host, kim Swanson, and we have some special guests John Malusky and Ryan LaQuay.

Kim Swanson: 0:35

I can't believe you did that, Brian. We just had a conversation about how we're going to pronounce our A's and I did not agree to that pronunciation, but I'm glad everyone can be here for today's episode yeah.

Brian Johnson: 0:48

So the reason in case you're wondering why why I did that we were today's episode is about the Hamburg or Homburg wheel tracking test, and the reason why we're talking about that today is because it is a new addition to the proficiency sample program. So that's why John Molesky and Ryan LaCroix are here with us, and what we were talking about is, when you go to a meeting, you often hear people say either Hamburg or Homburg, and we're going to call it just so everybody knows. I know we have some international listeners. We're going to call it Hamburg because we're American and that's just how we typically say it. So no offense to our international listeners about how we pronounce Hamburg or Hamburg, but I want to get that out of the way right up front so it doesn't become an ongoing issue on this podcast. Does that sound good, john?

John Malusky: 1:54

That works for me, Brian. Thank you.

Brian Johnson: 1:56

I have to admit, the composure was excellent. I don't know if you're watching this, but you guys maintained pretty good composure through that introduction, so congratulations. What we want to talk about is the proficiency sample program, not just because it's a new sample, but because of how we prepared it this time. So, john, why don't you give us some background on how we got here? Why did we add this sample program to our system?

John Malusky: 2:23

Why did we add this sample program to our system. Well, this has been probably a year to a year and a half in the making, Back in I'm going to say, the spring of 2023. During our technical exchange, there was a discussion with the administrative task group, which is AASHTO Resources Oversight of the state DOTs and they bounce ideas off of us and proposals and recommendations, and one of the recommendations was to investigate the plausibility of having a Hamburg Wheel Track proficiency sample program. So that's kind of where it originated, way back when a year and a half ago. And then throughout the course of that time, Ryan myself and the Proficiency Sample Program crew spent a lot of time having discussions, doing some research, talking to plant producers, other people such as NCAT, DOT staff, just trying to figure out a way to make this work and do it in a reasonable fashion. So it's been a little while.

Kim Swanson: 3:30

What were some of the challenges that you encountered while you were trying to prepare this?

Ryan LaQuay: 3:35

We talked with a number of different people in the industry DOTs and whatnot where they were doing similar programs, and they had a number of issues. The one big issue was making the quantity of samples needed for their participants.

Ryan LaQuay: 3:54

Because with Hamburg we're doing Hamburg, you need at least four compacted samples or slabs whatnot there? Or compacted samples or slabs, whatnot there. So we're looking at for us we put in about all in 10,000 grams of material and that needed to be pretty darn similar across the board for the whole thing. And way we've done that in the past for our mixed samples is we hand batch everything, hand mix everything. So doing that 200 times over, because we have about 160 labs in this program plus our extras and whatnot, is not quite feasible. So we had to figure out a better way to do that. So we asked around to these other programs had a variety of different methodologies for how they got their materials. So we had to kind of go through that and see what was feasible for us and what we could actually manage.

Brian Johnson: 4:54

All right. So when you did the first attempt at this, can you give us some background about how that went?

Ryan LaQuay: 4:59

We did a little pilot with, was it four?

Ryan LaQuay: 5:02

three DOTs, four DOTs, Yep a little pilot with uh, was it four, three dots, four dots? Um. So we, uh, we talked to a local manufacturer, got some plant mix, um, batched it out the way that we, you know, thought we were going to do it for for the production here. Um, and the way we did that first was we sent out two boxes, sample a, sample b, and we'd have them then batch down to their two individual specimens. Out of that, some confusion happened there on the batching and which sample is which. Is it sample A, the top sample? Is it sample A, the bottom sample? So we got that out. There had some confusion on the instructions and then whenever we actually ran the samples they blew apart. It was what, 3,000 passes or so, yeah.

Ryan LaQuay: 5:47

I think that's right and just absolutely exploded, so that one got a quick X of not a viable sample.

John Malusky: 5:54

The one thing that we noticed right from the get-go is that we're already seeing some challenges and variations just with preparing the material itself. Some challenges and variations just with preparing the material itself. Ryan and I compacted probably 20, 30 different pucks in our gyratory compactor in our facility to try to hit the correct specimen height of the 62 millimeters but also get the right air voids. And to the industry people who are doing this, that's pretty common and seems like it'd be a pretty easy thing. But one thing that we realized is that our compactor is completely different than other compactors. There are so many different makes and manufacturers and models out there that there appears to be quite a bit of variation. So when we're looking at some of the data in this round, we're actually asking for things like the number of gyrations. It took your gyratory compactor to get to the 62 millimeters just because of some of the variation that we're seeing. Like our compactor specifically, it's an older Pine 125X and it compacts from the top down and it was taking us like, specifically with this mix that we used for the round, I think it was in the low 40s. Correct me if I'm wrong, ryan. You did the last final one. I think it was high 30s, low 40s For us to get to the six to seven I guess six to 8% air voids at 62 millimeters of height. And we've seen other laboratories with the same mix, different compactor. It will take them 75 to 90 gyrations, so just immediately off the top we're seeing some variation with the compaction effort itself. So that was probably one of the biggest things we've tried to overcome and figure out from the get-go.

John Malusky: 7:47

Ryan already kind of mentioned the segregation issues that we may have with the mix. We actually spent quite a bit of time talking to the Ministry of Transportation of Ontario. They have a laboratory program, sample program, kind of like we do, and huge thanks to them for their support and help with this. But the first thing that they immediately told us is do not go with any mix over a half inch, 12 and a half millimeter mix because of segregation. Um, they were shedding some light on on what they do, uh, they actually kind of do a stockpile, uh type sampling, and they they advised against that due to segregation and they provided their procedures and protocols.

John Malusky: 8:29

Um, so we we kind of kind of shied away from that just because of their recommendations. Um, but it was, it's been. It's been interesting, so I'll say that. So the the design was just an initial challenge itself. I think we we went through what? Four different mixes, or three different mixes, until we targeted the one for the round with multiple trials, with different DOTs. So it took a little bit, for sure. I think that's why it took us probably 18 months to get it going.

Brian Johnson: 8:58

Yeah, that's great that you spent that extra time to get it right before you sent it out, so I think that should give people some confidence. Extra time to get it right before you send it out, so I think that should give people some confidence. What other data are you collecting in this sample other than the gyrations?

Ryan LaQuay: 9:13

Let's pull up the data sheet here and look at everything we've got. So we're looking for compaction device manufacturer and model, the average record temperature of the mix prior to compaction. Average time from sampling pour in the mold until compactor applies the load. Number of gyrations as mentioned before. Then we're going to have laboratories determine the bulk-specific gravity. We will be providing them a maximum specific gravity and then they'll calculate the percent air voids. And then when we go to the Hamburg we're going to ask for the wheel track manufacturer whether or not the root mean square error has been verified. And then the rut depth from 5, 10, 15, and 20,000 passes, stripping inflection point, rut depth at stripping inflection point and number of passes to failure.

Brian Johnson: 10:07

I don't want you to give away this answer, sure, but I assume you have an expectation of how many passes to failure on this sample, correct, correct? We do so you'll be. Now. This is our proficient sample program, so the ratings will be based on the average, but you have at least an idea. So should anybody expect to be able to complete the test as they normally do and not get a failure?

John Malusky: 10:36

So for this round I can't say we're 100% certain as to what's going to happen. The other trial runs that Ryanyan and I had talked about, the the pass count was substantially low. You know, our first one, we we used a mix that I believe was around 30 wrap that I think failed around 3500 passes. The second one was a standard virgin mix with no wrap at all and I think that was around 7,000 passes, ryan, yep, and this one from the data that we've seen, I would I'll say this you can anticipate it to be over 10,000. So we were hoping that many of the state specifications that are out there now are recommending a 10,000 minimum pass count. So our first goal was to try to at least hit that with the design. So we're anticipating that it will make 10,000 passes. We can't guarantee that on the average and what the normal distribution is going to look like and a standard deviation, but we're hopeful that it goes beyond 10,000 passes.

John Malusky: 11:42

The one thing that we had a discussion with some of the industry experts is do we want a sample that doesn't fail? And our answer to that was no, because if we don't get a failing sample at some point up to that 20,000 pass count. Then people can't determine a stripping inflection point as accurately, because you're you're getting much more interpret, interpretation or, excuse me, interpolation, rather than just getting a failure and being able to plot that so, um, yeah, it's, it's. It's been interesting to try to figure this all out and learn. Um, you know it's a lot, of, a lot of effort behind the scenes went into this. To be honest, probably the easiest part was the production. Once we got this figured out, had some discussion with the crew, the packaging was pretty easy.

Brian Johnson: 12:35

Before we go too far. I don't want to forget this. I want to go back to one of the comments Ryan made earlier. In case anybody doesn't know this test, can you please clarify when you said that the sample explodes? We're not sending out, uh, explosive materials correct.

Ryan LaQuay: 12:53

Yeah, we're not using gunpowder as mineral filler. Uh no, it's um, basically the rut the wheel as it comes through the sample um, shoves it all out to the side um, and does not nice and clean. It's like you take a heavy weight through mud and just kind of push it all out to the side.

Brian Johnson: 13:12

Yeah, so it collapsed. It collapsed and fell apart. So I want to make sure people understand that who don't know the test. I'm sure the people who know the test kind of had an idea of what you were saying, but those who don't probably were very curious about that comment.

Brian Johnson: 13:25

Let's get back to the preparation of this sample. So if you know about our proficiency sample program, you know that we prepare everything so carefully. We weigh up all the aggregate to the nearest tenth of a gram and it's got to fall within a very tight range and we add the asphalt to the tenth of a gram. Uh, and we were so precise in our measurement and we're so consistent that we come up with these really good samples that are that are repeatable, you know, able to be tested in a repeatable manner and come up with some good data. The big change here is that we didn't do that this time, not that that we weren't careful, but we did it a little differently and faster and more representative of what people do in practice. John, can you take us through your experience in developing this methodology this time?

John Malusky: 14:19

Yeah, the biggest thing was what we've kind of already touched on a little bit discussing with the producers and suppliers and other industry experts and the main issue is segregation. That was our biggest concern when we packaged this material. So we didn't want to stockpile sample right. We didn't want to just have a mixed truck come here and dump a pile on the ground or dump a pile on a stainless steel sheet that we had like release agent on it, because obviously when you dump in a pile, material rolls and that role is segregation. So after a lot of investigation and discussion we decided and settled on the use of a hot box trailer, which is basically a truck that's just got a diesel burner in, it, heats the sides and base and it's typically used for pothole patching. But that was a way for us to get enough material, keep it warm, able to be workable and we felt like we would keep it consistent. And the other major recommendation was I kind of already mentioned particle size. We started out with a 3, 8 inch or 9.5 millimeter mix I think the asphalt content was just over 5% to try to keep a little bit more liquid or keep it a little bit more viscous. So we had that kind of flowing capability to not allow it to segregate, just as if we were to package a fine aggregate or a sand. We would keep things in a moist condition to stop fine separation and particle separation. So just something completely different.

John Malusky: 16:01

It actually took us probably four months to find a hotbox trailer itself. We could have bought a new one, but given that we were only going to need this for essentially one day, we didn't feel that it was justified in the purchase. So we contacted multiple suppliers. I was at a trade show or two talking to different people to try to get one and we were fortunate to find a company that rents them, and they are only about 40 miles away from us, so we actually really lucked out. They had availability. We actually rented the trailer for a month to make sure that we had it, even though we knew we only needed it for a day or two. Plus, we wanted to account for things like the weather we wanted to have the truck here on site and any event that we had a rainy day we could hold off and not have to package and try to do our best to make sure that all things were accounted for.

John Malusky: 16:57

A ton of effort even went into the box size that we use for the quick release boxes.

John Malusky: 17:07

Ryan had mentioned before that we were going to take a larger sample and have the laboratory split and then, after the confusion that we so pumped into the whole program by having horrible splitting instructions, splitting instructions, we we made the decision and alternated our course to send out single samples for each portion of the wheel, so the front of the wheel, the back or so. For those of you who don't know the hamburg specimens, there's two pucks in each side of the machine, a front and a back, so for the left side of the machine and then for the right side machine. So that's why ryan had mentioned we had to send four samples. So rather than sending two boxes and have the laboratory split, to get the four or one gigantic box and have the laboratory split, we went with four individual boxes. So we had to adjust and contact our supplier for the quick release boxes and had probably seven or eight different sizes of boxes sent here and tested them to see how they would split and what would fit and all that good stuff.

Ryan LaQuay: 18:12

That goes well beyond just putting rocks in a box actually we got the boxes and we took some just random mix and also went and checked our different scoops, uh, to see what would work out. So we just hit a bunch of stuff in the lab, brought all scoops to see what would work out. So we just heat a bunch of stuff in the lab, brought all the scoops together and tried to figure out like all right, this scoop can get us to about 50% capacity, so two scoops gets us one, or this one gets about two-thirds of the way, so one full scoop and a little partial. So that was a solid morning that we spent just trying to figure out scoops and boxes and how we'd approach that.

Brian Johnson: 18:43

Did you identify the individual sample boxes to tell them where to put them in the? So you actually did label them.

John Malusky: 18:49

Yep, okay, all right, that's what I thought you were saying but I want to make sure. Yeah, with the sample labels, we'll say, you know, sample A front, sample A back, sample B front, sample B back. So the laboratories are hopefully putting in, putting them in this specific location for the machine and that's following all the way through the compaction effort.

Brian Johnson: 19:10

Yeah. So, the segregation issue. You mentioned the challenges that you would have with a pile. Obviously, dumping from the truck to the hotbox trailer is going to potentially have some segregation and then sampling out of that, I would think, would also have a risk of some segregation of the particle sizes. How did it look when you were, when you were actually getting your samples out of the hot box, where I mean because visually you'd be able to see if you were experiencing some segregation. What did you think?

Ryan LaQuay: 19:45

Yeah, no red flags. During the production process. Everything looked pretty well homogeneous. There wasn't like big clumps of 3S material or big clumps of fine material. Everything seemed pretty well blended. We are actively right now so I was late to this recording testing that to verify that it was all properly blended and homogeneous.

Brian Johnson: 20:06

Oh, so what are you doing to test that, Ryan?

Ryan LaQuay: 20:09

So we are doing a successful extraction, so we're burning in gradations, so we'll probably be done early next week and we'll have our final data on how well this turned out.

Brian Johnson: 20:19

And what does success look like in that result? What are you hoping to see? Look like in that result. What are you hoping to see.

Ryan LaQuay: 20:25

So we're going to look to have basically the distribution of materials, distribution of asphalt content, to be pretty darn close. So for our in-house blended samples we have some tolerance because human error and whatnot. So we're basically looking to make sure that we're still within that spread of tolerance, also looking against the standard for repeatability on that, just seeing that everything is generally the same across the board. So they're not going to be perfect, but we're trying to be as close as we can.

John Malusky: 20:59

Yeah, one thing I do want to go back to and kind of add a little bit of clarification is, brian, you had talked about using a truck to dump the truck into the trailer. That's not what happened, so we actually so.

John Malusky: 21:12

With the trailer situation, our crew took the trailer directly to the batch plant and the batch plant just dropped the prepared mix out of the hopper right in. So we eliminated one potential problem, uh, step of inhomogeneity, um, and it it seemed to to work out. Like I said, I think the only thing that we did notice was, after a little while, some fines and asphalt did stack up on the scoops, um, but after so many uh, maybe Ryan, there every 35, 40 minutes, we actually swapped scoops out to keep our scoops clean, and then the ones that were dirty and had fines built up around the lip, we cleaned those off. You know, to try to do our best to stop any kind of segregation. So, you know, we, like I said, we put a ton of thought into it to to try our best and we're going to see what happens with it.

Brian Johnson: 22:06

Now there are other wheel tracking tests out there other than the hamburg. How did we get to only have a sample program for that test and is there any thought to possibly adding or expanding this program to include other wheel tracking or rut testing tests?

Ryan LaQuay: 22:27

well, I assume we got here because this is the ATG's biggest target whenever they brought it up to us. It's becoming more popular for specifiers. They want to have data on this. That's something that we can get out of this, hopefully. But yeah, this is also our first toe in the water. If this goes well, we're going to look at all the rest of the balanced mix design programs or test methods and develop out through there.

John Malusky: 22:55

Yep, that's correct. We're looking at other methods. Some of the other things that we've already had suggestions for are indirect tensile strength and tensile strength ratio, so they're kind of the other two that are on the radar already for this. But we will see what happens. We're going to see how it goes. Hopefully the homogeneity and stability data come back and are reasonable. You know, the one thing that's kind of tough is we've always benchmarked our homogeneity off of our previous samples, so all the individual batching and hand mixing. So it's going to be a little bit more challenging, we believe, for us to hit some of those criteria because it's not prepared the same way. So we're going to have to evaluate the homogeneity and stability from a different benchmark, which is going to be a little bit different for us. So we'll see. I mean, I think we're very optimistic about the way things went and we'll see how it goes as we continue to test individually mixed and batched samples that we typically send out.

Brian Johnson: 24:15

Do you think you're going to expand that methodology to the other asphalt mixture sample programs?

John Malusky: 24:22

If we do see success with this and the materials appear to be stable and homogenous and the data that Ryan and our other laboratory technician generate, if it looks good, we will anticipate moving this type of production into our solvent extraction sample. It will help alleviate some time constraints that we experience and if the mix is consistent, then we'll go ahead and progress in that way and move to that kind of packaging event, first with that sample type, and if it continues to show promise of good, consistent data, we would consider making a change to our gyratory program and instead of having laboratories do the batching and mixing and all that kind of stuff by themselves, we would consider a just a, you know, essentially like a QC type program where laboratories would get boxes of mix and simply compact specimens and then, you know, do the typical volumetric testing on it and then kind of a branch off is the way that we set up our current gyratory program was sending virgin material to laboratories to test. It would kind of go to more of a mixed design program where we would send specific batching information but then the laboratories would be responsible for testing and providing data for all the components of a mixed design, so aggregate, specific gravities, angularity. You know then, obviously, your volumetric properties as well. You know GMA, bulk gravity, the stone, bulk gravity, the pucks, the asphalt, max gravity, vma, vfa, dust-to-binder ratio.

John Malusky: 26:19

So it would be more of an encompassing program for a facility who's specifically doing mix design itself rather than just QC checking the mix to make sure that you're hitting your volumetric properties. So there's a lot of opportunity to make some changes to the program and try to streamline the process a little bit for us and the facilities and the labs. And we're just going to see how it goes. We got to, as Ryan said, we got to dip our toe in the water first. And this is it, kim, do you?

Brian Johnson: 26:48

have any questions for them.

Kim Swanson: 26:50

I do. I mean, that seems like a lot of potentially exciting things happening based on the success of this round. We also have some other new samples in the proficiency sample world that we're doing, so I don't want to spend too much time on it, but can you go over just what's new coming up currently or coming up in 2025? That are new samples.

Ryan LaQuay: 27:15

Well, I'll say everything within the next six months. That'll cover it all. Yeah, sure. So end of this year we are doing a winter maintenance product sample. This was brought to us through ClearRoads and the DOTs sample. This was brought to us through ClearRoads and the DOTs. Basically, this said, we have our qualified product list, but we want to make sure that the testing laboratories are competent in what they're doing. So we're trying to do that with a liquid component and a solid component. Enrollment is open now, still open. We have it open until middle of November, trying to get as many people as we can into that one. We need more. So if you're listening and you have a chem lab who does this, send them our way, please. Thank you. And then in the beginning of next year we are splitting out the soil and chemistry and corrosivity tests out of the soil sample. So this is basically something that was already in the soil classification compaction sample, but we weren't able to modify the soil to have, you know, good results out of it.

Brian Johnson: 28:14

so we're pulling that off to the side, keeping the classification compaction sample as it is and making this one actually a viable testing sample when we get to those points, I think we'll have to have other podcast recordings to get into the weeds, like we did today on the Hamburg, so that people can learn more about them precisely. But back to one thing I do want to address on those the winter maintenance one. So far, just so people have an idea, what are our numbers looking like now?

Ryan LaQuay: 28:46

We have six participants.

Brian Johnson: 28:49

Six participants is a very sad number because we need more data. So the value of the program hinges on the number of participants, right?

Ryan LaQuay: 29:02

Yeah, so our statistical analysis will start to fall apart once we become under 17 participants. So that's our minimum benchmark we're looking for.

Brian Johnson: 29:11

So we've got a ways to go here A little bit. If you are far enough from the equator, enough to care about this type of activity winter maintenance no matter where you are on the planet consider signing up for this program, because I'm sure that people all over the world are interested in this and could probably benefit from the results of this program. So it doesn't have to be just DOTs or their subcontractors that participate in this.

John Malusky: 29:44

The program actually has a lot of additional potential. You know, not just for the, I'm going to say, physical properties of the brine solution and rock salt, right. One of the big things we're obviously looking at is particle size and distribution of you know the rock salt and how the gradation is met, so you know what kind of out of the back of a truck appropriately. But one of the other components that I think Ryan and I didn't even realize that was involved was the chemical component of the brine solutions. Many of the standards that we haven't included in the program yet because of I don't want to say a ton of interest, but maybe the interest isn't or the idea is not out there yet but for wastewater, right.

John Malusky: 30:31

So when all of this, the brine solution gets put on roads as a treatment that eventually gets washed into the environment. So a lot of the testing is for things like lead, arsenic, other heavy metals that are out there. So you know, it's kind of also a little bit more of an environmental side as well than just simply construction materials as as we're used to. So this is also another little toe dabble in the water of a different type of material than we've we've done in the past. Um, you know, but basically because of interest from from dots and members, so we'll see how it goes. But, uh, but yeah, if you agree with what b said, if you have the opportunity to sign up, please do so. Uh, so we can get some good data out there.

Brian Johnson: 31:15

I don't have any other questions for you on this topic, Kim.

Kim Swanson: 31:19

No, I think everyone covered everything that I had questions for. So I mean, I'm I'm happy yeah. Yeah, I mean, I'm not gonna lie. Some of this was way over my head, so that is why I stayed quiet most of the episode. But I want to thank you both for taking time today to talk about this and share about the new Hamburg Wheel Track sample, and then I do look forward to hearing about some of the other new samples as we get closer to those.

John Malusky: 31:49

Yeah, thanks, kim. I think one thing we should definitely consider is a follow-up to this. Once we do have the data back and we can analyze it a little bit more, um, and just kind of give a little bit more of a broad perspective on what we saw out of the results, rather than just, you know, z scores and ratings.

Brian Johnson: 32:04

Thanks again for being on the podcast, and if you are, uh, only listening to it, I want to let you know that we are now also showing this on our youtube channel, so there is a visual aspect to it. So, uh, and you'll notice that today is, uh, it's aloha friday here at the johnson household, uh, so I've got I've got my aloha shirt on and, uh, you three are clearly celebrating AASHTO Resource Friday because you have your AASHTO Resource branded polos on, and I would also say that this is highly unusual to see all three of you wearing one of those shirts, so it's not like you normally show up in an AASHTO Resource polo, so that's pretty funny. We hope you enjoyed the episode today and tune in for the next one.

Kim Swanson: 32:54

Thanks for listening to AASHTO Resource Q&A. If you'd like to be a guest or just submit a question, send us an email at podcast at aashtoresourceorg, or call Brian at 240-436-4820. For other news and related content, check out AASHTO Resources' social media accounts or go to ashtoresourceorg.