We get insights into the Asphalt Mixture Gyratory 55/56 sample rounds and share some tips to avoid common issues labs may encounter when running these tests.
AASHTO re:source Q&A Podcast Transcript
Season 4, Episode 13: August PSP Insights - Gyratory
Recorded: August 11, 2023
Released: August 22, 2023
Hosts: Brian Jonson, AASHTO Accreditation Program Director; Kim Swanson, Communications Manager, AASHTO re:source
Guests: John Malusky, Proficiency Sample Program Director; Ryan LaQuay, Laboratory and Testing Manager; Joe Williams, Senior Quality Analyst, AASHTO re:source
Note: Please reference AASHTO re:source and AASHTO Accreditation Program policies and procedures online for official guidance on this, and other topics.
Transcription is auto-generated.
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00:00:02 ANNOUNCER: 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. Now here’s our host, Brian Johnson.
00:00:25 BRIAN: Welcome to Ashton Resource Q&A. I'm Brian Johnson.
00:00:28 KIM: And I'm Kim Swanson.
00:00:30 BRIAN: And today, we're going to talk about hot mix gyratory samples 55 and 56 in our series of proficiency sample discussions. And with us again are our guest, John Malusky, Director of the Proficiency Sample Program. Welcome, John.
00:00:46 JOHN: Hey, Brian, thanks. Glad to be here again.
00:00:48 BRIAN: And Ryan LaQuay Laboratory and Testing Manager.
00:00:52 RYAN: Thanks Brian.
00:00:52 BRIAN: And congratulations on being the arm cover and hand cover model for the latest version of the 2023 standards.
00:00:58 RYAN: Thank you. If you see a neon green glove, uh, that's me.
00:01:04 BRIAN: That's him. He's famous.
00:01:06 BRIAN: And we also have Joe Williams, Senior Quality Analyst. Joe, welcome to the podcast again.
00:01:12 JOE: Hi, Brian. Hi Kim. Thanks a lot.
00:01:13 BRIAN: Let's talk about this round of proficiency samples. John, I'm going to start with you. Can you give us a rundown of how this sample is prepared?
00:01:22 JOHN: Absolutely, Brian. This is actually probably my geek out moment here. This is my favorite sample that we produce each year. I just think so much work time and effort goes into this. More in that, I think it's awesome. It's probably the best sample that we prepare each year. I love it. Just the amount of effort, quality time that goes into it. And usually, I mean almost every year the results are amazing. The data looks great. We never see any issues with it. It's just a really good, well designed sample scheme. And I think our group can be really proud of the work that they do on this one. But kind of. Go into the prep work of it a lot. You know, we had a podcast, I think. Was a week. Or two ago about the Marshall samples and beam samples very, very similar preparation when it comes to the production. Side of it, the team. And prepares the aggregate in size fractions, batches it up in the bags. Cans of asphalt are sent as well.
00:02:19 JOHN: All virgin material is completely raw and we develop a mixed design in house, but a lot of work from Ryan and. Myself and then. The laboratories get that mixed design. The batch recipe prepare it. They prepare one specimen for. Butter batch and a rice sample and then two compaction specimens for each side. Very similar to the setup and practice for Marshall and Bean, but this one just always seems to be like the cream of the crop sample for us.
00:02:45 BRIAN: Why is that and how does this design differ from the Marshall or Veeam?
00:02:51 JOHN: Oh, I don't think it really differs that much. I think there are. I'm going to say, you know, a few more things that we target specifically. I think I mentioned some of this, we target in the Marshall as well. But VMA and VFA. But there seems to be less variability with it than the Marshall. It seems like with the generators it's just more controlled. I feel like the participants really have a good handle on what they're doing and how things work and it the round just comes out so clean, like even, you know, even if you your laboratory. Ends up having a lower rating. It still ends up being pretty good. Just the look of. The scatter diagrams. It's just a like I said, a great round that that seems to work out all. The time.
00:03:34 KIM: How many people participate in this sample?
00:03:37 JOHN: So, This one's actually grown. Pretty substantially in the past few years, we have just over 1000 participants for a while there, it it was stuck in like the seven hundreds and eight hundreds and then we had a lot of pavement associations and dot start to work together. To use the. Program as a means of an assurance program. Between the two organizations and then at least some of them allow for like simpler dispute resolution when it comes to the testing of their own mix designs that they're making within their state. And that has really bumped up the participation in this program. We saw over a 20% increase in the past, probably two to three years. So that's been awesome. And like I said, the data that we're generating from it and the way that the round looks, it's excellent, good stuff.
00:04:25 BRIAN: How does this sample participation differ from others internationally?
00:04:29 JOHN: We still have somewhere between. I think it's 60 and 80 participants internationally, which is right around the same numbers from. Marshall, so there's still a reasonable participation level there. I just think that Marshall is still more readily available. Equipment's a little bit easier to get just a little bit of an easier way to procure all the things you need to run a Marshall and get a Marshall mix design. Marshall has been around for what, 70 years probably, I don't know. It's just a ballpark. But it's been around for such a long time, and there's just a great way to get the equipment for a worse gyratory it's a little bit harder, a little bit more expensive, but I mean, they're still on pace.
00:05:06 BRIAN: We got a lot of international participation with it. I'm thinking about why statistical analysis might look a little tighter than some of the other samples. And I'm thinking about all of the equipment that is much more carefully measured, much more carefully designed, standardized, you know, the angle is standardized. The effort that goes into just making sure that the molds are the right specification now. Do you think that contributes to this? Because I, I mean compared to the kind of wide open process of Marshall compaction, it seems like it would contribute to a more. Consistent test result across laboratories.
00:05:53 RYAN: I think the Gyrator definitely helps remove some of the human variability. Marshall, there's a little more hands on interaction, different options of equipment which are toy it's all in that machine. The machines handling the bulk of the work there, and that's a lot easier.
00:06:10 BRIAN: To control. So Ryan, I got another question. For you, now that you know that this is John's favorite specimen or favorite sample, which I don't know did. You know that already.
00:06:19 RYAN: He gets excited about it every year.
00:06:22 BRIAN: That was it was news to me. I had no idea.
00:06:23 RYAN: Yeah, he comes in with.
00:06:23 BRIAN: This was his favorite.
00:06:24 RYAN: A spring in his step, you know.
00:06:27 BRIAN: But now that you know that this is his favorite, does that make you a little more nervous about testing it?
00:06:32 RYAN: No, you know, we're pretty good across the board. We want to have good, homogeneous and stable samples throughout. You know, whether it's your favorite or not, no, there's probably more pressure. The ones that are our favorite, if it's not our favorite, that means we're going to do more work on those ones. So yeah, no extra pressure there.
00:06:46 BRIAN: All right. Anything interesting in 55 and 56 from the testing perspective compared to previous rounds?
00:06:52 JOHN: No, not when it came to testing on our end. I mean, you know, like I said in the Marshall and this is. Kind of the first round where I took one of them and Ryan took the other. So this is Ryan's really first go at at volumetric mixed design and the numbers are really good. So like I. Said we're did another solid job with the design and looking at our values compared to the grand average, we nailed it again, we'd mostly fours and fives. So things seem to work out. Very well for us on our.
00:07:17 BRIAN: End now, Joe, let's go over to you with some accreditation questions. What do people need to watch out for related to accreditation on the gyratory samples? Other than not submitting results, I'm not going to give you. That easy out.
00:07:30 JOE: Alright, well, I'll, I'll. Probably, you know, put a plug in there for that at some point. From an accreditation standpoint, this one is one of the smaller samples that as far as line items, there's only a handful of tests in this one similar to the Veeam and Marshall Samples we talked about in our last one, but none of the compaction programs include data for T275 or D1188. That's bulk specific gravity by paraffin or parafilm, so if there would happen to be under an accreditation suspense. And for the regular bulk specific gravity, T166 or D2726, uh. Suspension of accreditation for the paraffin or PARAFILM standards would also take place. The only other kind of thing here is some people might notice that this sample includes line items for. T100. Which is actually a soils test and the reason that that one is included in this sample.
00:08:30 JOE: Is because R35, which is the standard practice for super pave mixed design, requires that the mineral filler, the specific gravity, be determined using T100. When we first started accrediting for that a few years ago, probably in 2015 or so, it was kind of a headache for some of these. Asphalt labs to be enrolled in a soil proficiency sample program just to test 1. 100 So what we did was or what John did was he started adding a small baggie of mineral filler to his samples for the laboratories to perform T100 on, and we actually moved that into the aggregate scope. So hopefully that saved some lads a little bit of money, but not having to be enrolled and soil just for that one single. Test we do get some. Questions from labs that are accredited. For soils testing that have T100 under there, you know do I have to submit data for this test and the answer is no. The only time you need to submit data for that test.
00:09:26 JOE: Is if you have T100 Merrow filler under the aggregate scope, which really you should only have if you are accredited for R35 under the asphalt mixture scope. So just those two things there, we haven't yet received our lists of suspensions to review, so not really sure how many, but again. Similar to those other compaction ones, usually the T-209-D2041 maximum specific gravity that tends to be the one that we do the most suspensions for out of this one, and actually with the way that the calculations work with T312 sometimes that there's a suspension for that. You can see it's a suspension for. The 312 and the percent maximum specific gravity for the 8 and 100 gyrations cause those things are kind of tied together, but as always, a lot of our suspensions come, at least in some part from laboratories not submitting data. So make sure with all the PSP programs get data submitted. So you can avoid.
00:10:29 BRIAN: Or at least try to avoid suspensions just for just for that. And I know that some of the laboratories, even though we haven't gotten our list of laboratories that need to be suspended, they reach out as soon as they realize they're going to get suspended or they got their low ratings. Have you had any inquiries from your laboratories yet about that? I'm not necessarily sure about.
00:10:48 JOE: In this sample, but usually in other samples we will get those inquiries. And so yeah, that's a good reminder is that accreditation suspensions come from low ratings or no data. So the low ratings would be a 0 or A1. On the same line item for both samples for two sample rounds in a row. So it does take actually 4 consecutive samples, not sample rounds, but actual samples for a suspension to take place. So if you just got a one-on-one sample this round, there's no need to reach out to us. But you know, you do have to take corrective action. On any low ratings per laboratories quality manual and file, those corrective actions and those reports and investigations. Is because when our assessors come around to your laboratories, they will look for.
00:11:38 BRIAN: Records of that? Yeah, that's a good point. And the corrective action process starts when you get twos. Even though we don't suspend until you get zeros or ones. So you want to start making those improvements when you get into that low rating area of 2 and -2? Those are great reminders. Joe, thanks for That.
00:11:56 JOHN: so I'm going to touch on a little point here. You know, Joe, you just got done. Missing some of the things with the accreditation program and that line item about the mineral filler in T100 and how we added that. And then I actually want to point out line item 3 and the data sheet here a few years ago we had a recommendation to add this test property and that is the mass of the dry specimen prior to performing the bulk testing. And I know we got some feedback like from participants. What the heck are you doing? Why are you adding that? Who cares about that dry mass? That dry mass is actually a direct result. Of how well your laboratory prepared the specimen and scraped your mixing bowl out. And you know I've got some data here. I wanted to take a look at this for a little while and now that we've got some information from a few years, we can definitely see a trend with laboratories and how well they scrape and how well they mix and. Now it relates to their resulting data.
00:12:50 JOHN: It's pretty interesting. I actually pulled data from about 7 participants from this round. Who were all greater than 3 standard deviations away on both samples 55 and 56 for that bulk puck, and not really surprise here, but every single one of them had some other test property that had a low rating as it related to the bulks. The heights of compaction. 8 and 100 gyrations, and the percent of maximum gravity after 8 and 100 gyrations. So it's pretty interesting to see. I mean, I'm not really super surprised by it. It's one thing that, you know, as a laboratory, if you're testing and mixing. Should be looking at those values. What's the batch final batch mass and how much do my pucks weigh? Am I getting everything I need to out of that mixing bowl actually really interesting too to look at the data and. See some laboratories. Who have way more material in their pucks than what was in the mix design.
00:13:53 KIM: Do you have any tips for how to do that? Maybe Ryan has some tips of how to properly? Scrape the bowl so you don't have not enough, but then also I'm very confused by what you just said that they have more material. Than what was. Before, so I'm confused by that, but. I'm just looking for tips. For laboratories, not for me personally, because I will never do this test.
00:14:16 RYAN: The main thing is that you want to obviously heat. Heat is his key for. If you start getting too cold, you run the risk of the material sticking to your bowl and not getting it out of there. You want to make sure you're consistent across the board. Whatever you're doing, make sure doing the same thing over and over because you know it's not going to be clean to you know, down to silver whatever color you're mixing bowl is. But you know, if you look at that same sort of consistency, same sort of color you know make sure you get definitely sure getting your finds out of the bottom. I know definitely some of our mixing bowls, the very center of the bowl likes to accumulate material. If you don't give that little scrape at the end there, you can. There's that as.
00:14:50 JOHN: Well, there's definitely a build up issue. That's one thing that we see happen and you know to kind of tear into that ignition and solvent samples when we mix those by. Hand we see. A build up over the course of time. So we stop halfway through, we clean the mixing bowls, rebutter them, and then continue on. So that's one thing that that we definitely see, but it's really apparent. And I got some data here where our batching for this round the total mass of the mix design was 4965 grams. And we've got some laboratories reporting close to 5000 grams in their pups and you know people think well, how could you do that? And I mean, obviously the rice is a way to do it. You're right. We have a butter batch and we ask laboratories to butter their bowls first. But if you're getting almost 50 grams extra in the mix, I don't think you're cleaning out your bowl enough prior to even doing the. These are proficiency tests you want to try to do your best to make. Sure things are. Clean and buttoned up as well as they can before you start. So if you're not taking that kind of diligence and making sure that you're getting your mixes the way they need to and comparing that mass, you definitely want to take a look at it, it's going to reduce the amount. Of variability that you're seeing with the samples and your results?
00:15:57 BRIAN: Yeah, that's a tricky thing. If you're a laboratory that's just used to testing already mixed samples and all of a sudden you have to mix it yourself only once a year, you can get out of practice pretty easily. But I know when we make proficiency samples where we mix back in the. Warehouse area we've run into that situation, of course we're mixing a ton of samples at once, but the first couple and actually I shouldn't say just the first couple, sometimes you get in a groove and then you'll mix the sample and you'll see something go wrong like it just the way the mixer is is operating in the way that the aggregate. Is in the bowl. You'll have like 1/2 inch chunk fly out and then you have to go get that and hopefully it's not. You know, covered in dust or some, you know, you're not incorporating other things into the mix, but you know, luckily that would probably be not a whole lot anyway, with one piece of aggregate getting out.
00:16:52 BRIAN: But you do have to get that aggregate, especially 1/2 inch piece back in there because that's it we don't. There's not a lot of half inch material in the mix to begin with and that could throw you off a little bit. So you have to be cognizant of those things and you know, try to try to get as representative sample as you can out of what you're mixing. If you ever need tips before you work on that, that would be a good thing to reach out to us about. If you're not sure what to do, or if you say you know I have, I've never mixed. Before, if you're new what? Do I even use for this? You know that would be a reasonable question to ask. So since it I'm saying that, but so why don't I pose that question to you, Ryan, if I'm a new laboratory and I've never mixed before and I say I don't know what to do with this. What would you tell me?
00:17:36 RYAN: I would ask if you had any experience in cooking. It's the same sort of process well.
00:17:42 BRIAN: Only ramen noodles and hot pockets in the microphone.
00:17:45 RYAN: Well then we got a dual threat here. So basically, you know, make sure. Before you start diving into it, make sure your prep is ready. Make sure you have your equipment. Make sure you have your hot like this, something I've run into as well where you know, get ready to mix up. Got everything set out and I realized that I'd never turned on the hot plate. I turned off the. Other day it got turned on in the morning, so like well. Now we got kind of I hit a speed bump. All my materials ready, but my equipment isn't ready. So make sure your materials are ready. You know, make sure your equipment's ready to go look at the whole process before you start diving in on step one, make sure you have a place to put your material. You know, things like that. So just kind of look at. That the whole process you know holistically before you start chopping away at it.
00:18:27 KIM: That might be why I'm not a good. Baker, because I do not follow if I'm following from taking your advice, I yeah, that could be part of my problem. So thank you for that tip there, Ryan.
00:18:38 JOHN: Yeah, yeah, you're not wrong. Follow that recipe. I mean, you know, same thing. We also see some data on the opposite end for this weight where the sample size is around 4900 grams and it's kind of like. OK. We are 65 grams light more than likely none of your heights are going to be even remotely close because you don't even have enough material in the mold. So you also got to be careful on that and too, just make sure you're following. The batching the right way and following that recipe, yes.
00:19:03 RYAN: So whenever you have new trainees in the lab, I same thing as baking, you know, like how do I mix it? Well, have you ever made cookies ever made? Pasta before same. thing, you had your wet stuff to your dry stuff. Just follow your recipe. Follow your proportions alright.
00:19:15 KIM: And for clarification, we say butter. You're not actually meaning butter, right? That's kind of like a crumb coat. If you're, if you're going with the analogy, you're kind of crumb coating the inside of your bowl, and it's not actual butter. It's the term that is used.
00:19:31 JOHN: I know you're not as technically savvy as the rest of us, but did you really? Just ask that Question.
00:19:35 RYAN: no, they're so that for using release agent, we've had to tell people don't use the butter flavored cooking spray.
00:19:35 KIM: I wanted to clarify that question. Really. OK, OK.
00:19:45 BRIAN: Kim, you do technically like you will find butter flavored cooking spray in laboratories. Customarily, you will find that, yeah, that they have been spraying stuff with that. And I never it never occurred to me that someone might have taken the buttering. Term and persist that because of that.
00:20:02 RYAN: Literally yes.
00:20:05 BRIAN: But I wonder now if that's what happened.
00:20:08 KIM: I'm just here to ask the questions that you think are so silly that who would think that I'm here to ask those questions, John. So there you go.
00:20:16 JOHN: I'm just. I'm just going with it.
00:20:18 BRIAN: Feel like we've had a real breakthrough. Today we've learned so much.
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