August PSP Insights - Polymer-Modified Emulsified Asphalt

AASHTO re:source Q&A Podcast Transcript

Season 4, Episode 14: August PSP Insights - Polymer-Modified Emulsified Asphalt

Recorded: August 22, 2023

Released: August 29, 2023

Host: 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. 

[Theme music fades in.] 

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. 

00:00:20 KIM: Welcome to AASHTO resource Q&A I'm Kim Swanson. We are without Brian Johnson today, but joining me to talk about another PSP Insights episode are your favorite guests, John Malusky, Director of the Proficiency Sample Program. Welcome, John.

00:00:34 JOHN: Hey Kim. Thanks.

00:00:36 KIM: We also have Ryan LaQuay, the Laboratory and Testing Manager, welcome, Ryan.

00:00:41 RYAN: Thanks, Kim. Long time caller, first time listener.

00:00:44 KIM: And we have Joe Williams, Senior Quality Analyst or Heirloom Quality Analyst. If you have listened to previous episodes, welcome back, Joe.

00:00:54 JOE: Thanks Kim. Glad to be back.

00:00:56 KIM: In this episode, we are talking about the polymer modified emulsified asphalt, or PME samples, and this was around 1 and 2. So this is our first round of the sample. John, what can you tell me about this sample in general?

00:01:14 JOHN: First, I think we should take a moment and give Kim a round of applause for saying polymer modified emulsified asphalt proficiency sample scheme. That's a tongue twister, and she practiced before, and she just nailed it. So good. Work him.

00:01:27 KIM: I am leaving that in, so yes. Thank you, John.

00:01:33 JOHN: So yeah, rounds one and two here. And you know what? I'm going to do my best to really stay quiet on this one. This scheme was developed by Ryan LaQuay, our Lab and Testing Manager. This was an opportunity for him, so he kind of went cradle to grave. Hopefully not really grave with this one, but [RYAN: Early grave.] he early grave. He was the one who took the whole thing under his wing to let it roll. So Ryan, go ahead, let her rip, man.

00:01:56 RYAN: Sure. I mean, so, I mean, let's start with why we're even doing this.

00:02:00 KIM: That was going to be my first question and I missed it so great. Why are we doing this, Ryan?

00:02:04 RYAN: So basically, is we're seeing a lot more use of polymer modified emulsified asphalts in the industry, specifically with pavement preservation. You know, we already do the standard emulsified asphalt sample. We're starting to see more of this and it's becoming more prevalent and asked the States and people that work with us a while ago, like, hey, what do you want to see and this was top of their list so. Here it is.

00:02:26 KIM: This is 100% new sample. Unlike some of the other samples that are one and two this year that are just kind of rebranded, but this is 100% brand new thing that we're doing.

00:02:40 RYAN: Right. I mean if you want to split hairs, we'll call it. It's almost like a spin off. Uh, and that it's got its origin story in the other sample, but it's got its own unique characters.

00:02:49 KIM: I love that analogy. That works with me completely. So this was the first round of the samples and what do people get with this sample?

00:03:00 RYAN: They get 2 bottles of liquid emulsified asphalt. Nothing too fancy with that, similar to our other sample.

00:03:06 KIM: This one is different from the emulsified asphalt samples, which we have renamed to be specific. That's unmodified, correct.

00:03:14 RYAN: Right. So this one we got from one of our suppliers and it was modified with a latex Polymer.

00:03:20 KIM: What has happened with this first round? What are we seeing in the results that everybody submitted?

00:03:25 RYAN: Oh, we got a couple of interesting things here. So First off, we sent this out to 255 laboratories, which is our standard must fight asphalt round participants. If you run the most fight asphalt tests, you're running this one as well. Now, we had almost 240 submitted, which is a solid 95% or so return on that, which will take that every day of the week.

00:03:45 KIM: What's unique with this sample round?

00:03:47 RYAN: So there's three tests that you run, and then after that there's. For preparation methods and then this test split out again from there.

00:03:54 KIM:. So looking on our website on the proficiency samples tests and sample types page. The Polymer modified emulsified asphalt sample looks really complicated. It's a very big sample table wise. Is it actually that complicated or is it pretty straightforward?

00:04:13 RYAN: It's not as complicated as it looks. The issue of why it looks so busy there is that there's four different preparation methods for this material and working on how we get the asphalt residue out of the emulsified asphalt material. And so for this, there's the options of the distillation, the vacuum distillation, evaporation and low temperature evaporation.

00:04:33 KIM: I don't know what really any of that.

00:04:35 JOHN: We've received a lot of comments in the industry. About this with this sample, there are, you know, traditionally 2 methods that you use to collect the residue. It's the residue by distillation and the residue by evaporation. When you add polymer into an emulsion material or even a liquid asphalt material when you heat it up to high temperatures. The polymer breaks down and you lose the benefits of the polymer in that asphalt.  So we have the other two techniques that are used to get the material which are the lower temperature technique. The first one is the vacuum distillation and the second one is the low temperature evaporation technique. So those two techniques are meant to keep the polymer in a stable condition where it can actually be utilized and improve the performance of the asphalt. So that's basically where the split comes and that's why we now have four different. Techniques for residue and that's why they're split out four separate.  Ways because we're expecting to see different results from each technique.

00:05:33 KIM: If a laboratory is performing the tests on these samples. Do they just pick one of those methods or do they do multiple ones?

00:05:41 JOE: So typically, in the past with the EML samples, if a laboratory was accredited for residue by distillation and residue by evaporation, which both fall under Astro T59, they would do.  Both of those. Preparation methods and then the underlying tests with them as well.  With these newer ones that we're doing with the polymer modified emulsified asphalts, we're actually not offering accreditation for those yet. So there's no. Requirement for them to do those and their underlying tests. However, we are simply asking labs at this point if they have the equipment to perform these methods. If they have the time to do this, it would be a great data collection process for us to help with these standard developments as well and also to. To look at if there's enough laboratories interested in this that we want to start offering accreditation services.  To add on the question that Kim just asked, is there enough material for them to do all four and the testing under all four of these methods?

00:06:45 RYAN: Well, as of right now, no, that was the feedback we got of a lot of, hey, we need more. So we're going to up the sample size next year to encompass.

00:06:47 JOE: OK.

00:06:53 RYAN: All that because, you know, while I planned it, I was like, oh, this will absolutely. Here's enough for this. Here's not for that. I forgot to duplicate that four times over. So yeah.

00:07:01 JOE: You live and learn.

00:07:02 JOHN: Yeah, exactly. So here's thing that we neglected to count on is that we had obviously way more than enough material. That we needed to. Perform those core tests right? The ones that are part of the accreditation, so the traditional. The operation and the traditional distillate. More than enough material, but one thing that we didn't realize when you start talking about these low temperature techniques and you're getting the residue, it's not like you're getting a simple, small amount of residue for something like a dynamic shear rheometer test. We're talking about filling up pen cups and talking about filling up elastic recovery molds, and you need way more material than we anticipated.  So just say for example, if the residue is, you know it's a 50% residue.  And we have 500 extra milliliters of emulsion. We're only going to get ballpark 250 grams of material. That's not enough to do all of those other techniques once they're used, it might only be enough to do like 2. So one thing that we're going to do, Ryan and I have already discussed this for the next year's round, we are essentially going to double the amount of material in there. So that should give labs enough. Product to do all the tests if they want to participate.

00:08:08 RYAN: In it, Joe, you're talking about, you know.  Looking at participation of these uh for the vacuum distillation method, we had zero responses.

00:08:17 JOE: I was going to ask that as. For our listeners and the analysis just got finished, so I really haven't had a chance to look at a whole lot of this with those newer standards that we're not accrediting for. So the participation was.

00:08:26 RYAN: Pretty low with those on that one. Yeah. And then for the low temperature.  Evaporation looks.  Like 6.  Yes, 6 responses, definitely. Those two are newer methods. They're not specked out in the polar modified emulsion specification, but there's some talk about these catching on, so getting ahead of it. Hopefully

00:08:43 KIM:. Alright. I love that continual. Improvement mindset on that. Lessons learned. We know we're going to. Send more material. Is that going to?  Increase the cost of the sample.

00:08:54 JOHN: It will a tiny bit, Kim. It's not going to be substantial, but we've actually already built that into next year's fees. Our fee schedule is posted now for 2024, pretty modest increase in samples and that will help cover the cost of that extra.  Serial our bulk billing process happened September 1st for PSP is actually probably a good time to mention it. Any of the laboratories are listening in on this that are participating in the program. Your invoices will be coming out to you here in the next about 2 1/2 weeks, so be prepared.

00:09:25 KIM: So Joe, since this is the first round of a brand new sample, are there going to be any accreditation shake ups around this sample or not yet?

00:09:40 JOE: No....I will elaborate. [KIM: Please.] you mentioned this before with several samples that we've talked about recently on the Hveem samples splitting out into three different ones, the coarse aggregate and fine aggregate getting shaken up into degradation and graduation and gravity. With those changes, we did continue on from the previous sample types. As far as accreditation decisions go, specifically suspensions is. What I'm talking about with this one being the first of a brand new sample type, there won't be any accreditation decisions from this. We won't be reviewing these ratings for anything. Keeping that in mind, as with any PSP sample, if the laboratory does receive low ratings, it is still up to them to investigate. Those low ratings, do a root cause analysis and implement any corrective actions and document that process as well and file them away per their quality manual procedures.  Because as assessors come through. Who and perform assessments at the laboratories. They will look for records of that corrective action. So. So, no, no accreditation changes or decisions or suspensions, but lab should still be doing their corrective action reports for any low ratings.

00:10:49 KIM: That's a great reminder. I know I forget about that part of it just because I'm.  Not a laboratory.  So, but I often forget that there is action taken on their end for all low ratings. Whether an accreditation decision has been.  Made or not based on those low ratings, I also say just for you, for a reminder for people to submit data because I feel like that is a common theme of Joe every one of these episodes reminds everybody to submit data. So I'm just going to throw that out there for you.

00:11:18 JOE: A lot of our suspensions are caused in part by data not being submitted so so get it done. Make the time.

00:11:26 KIM: What else have we learned since this was the first round you mentioned already? You more material to do all the optional tests? Is there any other lessons that we've learned?

00:11:34 RYAN: There's a couple. So the first one I'm going to start. Residue by distillation is at a decently high temperature, and as John mentioned, for high temperature your polymer breaks down. So what we had this year was we ran at this standard testing temperature in standard. Next year we'll be bringing that temperature down to something that's a little more manageable for the material and should help with the results because. We can now look across these different preparation methods how the results turned out and they're very different between.  And the distillation, recovery, evaporation, recovery and the little bit of low temperature evaporation recovery that we got back the four test methods that kind of compare and contrast across these three preparation methods, percent residue penetration of the residue elastic recovery and ash content as far as percent residue for the distillation and evaporation, those were within.  .3%, which? That part's pretty tight. It's what happens with the residue afterwards that we see some some variability for the penetration of the residue, the distillation residue was higher than the evaporation recovered material and the evaporation recovery material was higher than the lower temperature evaporation. The cover material, so kind of stepped down as the temperature went down. So you're seeing that impact of of the heat on the material essentially.

00:12:51 KIM: And for those who are not terribly familiar with that, what does that actually mean or what does that tell us?

00:13:00 JOHN: The biggest thing with this is when we're talking about the standards developers. So when you have either AASHTO or ASTM writing the specifications, they're looking at the tests that are applicable at the on the residue. And the specification can't go and say that all of these are equivalent if the penetration on the residue for the distillation right now, as Ryan said, we're showing about a. The 118 then on the penetration from residue by evaporation, we're showing 9. The one and then on the penetration on residue by low temperature evaporation, we're showing a 75. Those three values are so far off now. There might be a they might put a minimum value on the specification. However, there's so much variability there that we need to hone that in we need. To figure out. Why that variability exists and how to bring that down so those methods are either considered equivalent? Or they're parsed out where we can use that data and have some credibility and and backing behind it for the actual, you know, results and specifications.

00:14:07 KIM: So when you said we need to hone in, who is that we that. You're referring to.

00:14:12 JOHN: That's going to be the collective industry agencies getting together to work on, you know, modifying the standards, revising them to make that systematic air that we've got built in there. Narrow that down so. We're getting more reasonable, repeatable results.

00:14:27 RYAN: So we kind of expected the residue by distillation materials to perform poorly in the testing because we're treating them as such high temperature. We expected it to not do well. We definitely see the difference. However, going off the spec M316 here for polar modified but lost sight asphalts it meets for CRS 2.  With the distillation requirements I have.

00:14:46 KIM: OK. Another question, so for the statistical analysis of it, was everyone getting the similar expected or unexpected results or were they vastly different across everybody or was there variability in that?

00:15:04 JOHN: We did see some consistency. So you know, when we looked at those specific techniques, the 1S values essentially matched up to what we saw before collecting the residue. When we looked at the actual test methods themselves on the residue that was pulled, that's where we saw some increased variability between what we typically find in the standards. And that's a product of the evaporative technique.  In the introduction to these tests in the sample scheme and also the variability that we introduced by using the higher temperature for the distillation. So once again, you know a lot of stuff that we can button up on our end, but also there are things here that need to be addressed with the standards developers and us as a community to make sure that we get this to where it needs to be.

00:15:45 RYAN: So just going off the mention of standards development, that's also something else that's kind of, it's not, it wasn't the plan, but it's also it's part of the results here by going through these and dealing with actually getting out there to the customers will not we're finding parts where the standards Don’t Line up exactly with reality. So for example, the low temperature evaporation method. Basically you're cooking it off at a low temperature, you end up with a ball almost right, asphalt. I'm trying to. Do a good other things so. Yeah, so it's malleable, but it's not. It's not liquid, it's it's a solid. Uh for the 1-2 test methods. You're supposed to pour it into molds, which isn't necessarily possible. I guess we just suspend it and do the the pitch experiment. Just let it go for a while. It'll get there eventually.

00:16:29 KIM: That is actually what I just was thinking about in my head, but I was also thinking like, I mean, yeah, you can't really poor Silly Putty.

00:16:36 RYAN: Right. But no, there's some parts there where things may have been added or added into the standards which don't quite reflect the actual current practice.  We'll present that back to the ASM subcommittee or the Astra sub committees and hopefully develop these standards a little bit further.

00:16:51 KIM: Yeah, it looks like there's some good opportunity for some process improvement in that respect though, has there been any other lessons learned? I mean, we've talked about a few already. What else have we learned?

00:17:01 JOHN: Yeah. One thing that we definitely learned as well is there appears to be a decent amount of interest in the optional method that we had in the round, which is the quick boil. This method was published in ASTM in 2022 as a new method. Can't remember what committee it. Came out of but. We added it in last year to try to help the standard developers get some data for precision and bias. And you know this is a brand new test method. We haven't offered assessments and accreditation for. It but we. Had participation of 28 labs, so to us that sounds like a potential for a new assessment. And accreditation for that specific test method. So that might be something here that we need to discuss with the accreditation program, the assessment program and start getting people accredited. That the other interesting part about that method is it's so far showing pretty consistent data with the traditional residue by evaporation method. Just comparing the data we're seeing for sample one, we saw the traditional residue by evaporation to show results of 70.01%.

00:18:07 JOHN: For sample one and for sample 269.93%. When we looked at this new quick. oil method which calls for a different amount of material to be used. We saw a value of 70.06 for sample one and for 70.20 for sample B. So even though it's a completely different method by than the traditional evaporation method, it's looking pretty good looking like. We're seeing comparable results.

00:18:35 RYAN: In more participation than the other two newer methods as well.

00:18:39 KIM: Good, I guess. I did have a question. We normally have extra proficiency samples available for customers to buy if they wanted to test this or do this, do we have any available? Since this is a new sample, do we have that in our inventory? If people were interested in using it for in house training or something like that?

00:19:00 RYAN: If they want to take our supply off our hands, we'll give it to them, but we do not certify it as good quality or comparable. Because it breaks.

00:19:08 KIM: OK.

00:19:09 JOE: Yes, that's a good point to be brought up to. There's no not going to be any suspensions with this round. So an EML  Comes out unmodified emulsified asphalt. When that one comes out, so we don't see many, but we do see a handful of suspensions from those rounds. And unfortunately, laboratories just have to carry that suspension until the next sample round because we can't send XPS just because the material breaks. Down and the results aren't reliable.

00:19:37 RYAN: Yeah. And it also ties in the fact of, you know, we we ask people to do this, but we'll keep asking, especially the most find asphalt samples, test those as soon as you get them, please avoid the chance of of having any breakage. You know, the longer it goes, the less likely it is you're going to have the good results.

00:19:52 KIM: Yeah. So if for this example the ship date listed for the PME is the mid June was June.  15th and then the closing date for it where you needed your data submitted by August 10th. That's about two months. So if you tested it on June 16th versus August 9th, is there going to be differences in the data that's submitted?

00:20:16 RYAN: Definitely some. The question comes down to whether or not it's significant and you run the risk of it possibly being significant. It might not be, but there's a chance of it. So for example, for our in-house testing, we test it after packaging before shipping and then we test it at the end after the sample closes. The samples that I tested at the end, every single one, was appreciably broken. And I don't know if you know the term broken. We keep saying it right.

00:20:40 KIM: Assuming it was like separated like when you have like oil and vinegar not mixed together.

00:20:44 RYAN: Right, right. Except you can't just shake it up as as easily. So basically, there's chunks of asphalt floating around in, you know, water, chemicals solution. You can start, you can heat it up, you can stir it up a bit, but it's not going to get back to that initial state. So we tested the the stability samples and they passed our statistical analysis it.

00:20:47 KIM: Ohh well that's sad.

00:21:05 RYAN: Wasn't as pretty as those samples are, but it did technically Pass.

00:21:09 KIM: now, is there anything that we can do to make it more stable or is it just the nature of the the product.

00:21:15 RYAN: Nature of the beast. Yep.

00:21:17 KIM: OK. And are we thinking of maybe shortening or is it an option to shorten the amount of time between ship date and closing date to reduce that variability?

00:21:27 RYAN: For the listeners that can't see John's grin and shaking head. That's an emphatic yes.

00:21:32 KIM: So you'll have fewer months.

00:21:33 RYAN: Yeah. So.

00:21:33 KIM: You have less than two months to do it.

00:21:35 RYAN: Right. So that that's our trade off of if we shorten the period, you know we might get complaints about how it's not enough time. But we're also looking at having less broken material.

00:21:45 JOHN: The sample viability is really more important and. I think at this point six weeks is probably long enough to test the product. We actually extended it traditionally. I mean, we're talking 10 years ago our testing time was actually only six weeks. Once we gained our ISO 17043 accreditation, we saw such an uptick in international. Participation we had concerns about our international customers getting the samples with enough time to test. So we expanded the testing time to 8 weeks to allow an additional two more weeks for the labs to get their material and test. When it comes to a sample like this, typically emulsions. And one of. The tests is storage stability and it's 30 days is the typical test where there passes or fails. This is one of the situations where you know it may pass at 30.  From the supplier, which is perfect, that's exactly what the ASTM specifications says, but it may not pass at 45 and at a plant they have the capability to, you know, remix. They could do what they need to to keep the material in a great state for production and test.

00:22:50 JOHN: We don't have that situation, right. We're sending the samples out in plastic bottles and hopefully the lab testing as soon as they get them. So our only choice in this situation is to cut the testing time down so we can anticipate that next year instead of an 8 week testing window, the labs will have a six week testing window.

00:23:07 KIM: Any other future changes that we're going to make to the sample going forward based on what happened in the first round?

00:23:13 RYAN: Well, I think we're going to keep the test method schemes as is. If we see any sort of changes or sort requests from the States and specifiers of hey, we're starting to look into this, we'll start looking at that or we're checking out of this method entirely that may impact it. But as of now, going to keep it as is. Just said before, we're gonna increase the amount of material that comes out. We are going to be a bit more specific in the instructions as far as testing temperatures and some of the preparation methods there. I think that's my main notes for the next rounds.

00:23:41 KIM: Now if I remember Correctly someone mentioned that participants that were already in the unmodified multiplied.  Asphalt samples were automatically. Enrolled in this new polymer modified emulsified asphalt samples is. Was that correct? You're automatically enrolled in that.

00:24:00 JOE: That's correct. Any lab that was in the previous EML sample that is now specifically unmodified, emulsified asphalt was auto enrolled, and the polymer modified sample. They can't opt out of it, they need to be enrolled in both, and they need to participate in both.

00:24:19 KIM: With that participation then will eventually, I know there's no accreditation decisions happening now, but we'll eventually if they get satisfactory ratings in the first one, I think this year polymer modified assaults came out first.  So if they get satisfactory ratings on the overlapping tests and the polymer modified ones when the unmodified. Version comes out, they still have to participate and get satisfactory ratings. Or do they have a grace period kind of thing?

00:24:55 JOE: They would still need to participate. Yeah. Yeah, because because keep in mind that if they don't participate and they don't participate 2 years in a row, that's going to lead to a suspension. So it's sort of like this. We have a lot of labs that are accredited for both ignition oven and solvent extraction.

00:24:57 KIM: OK.

00:25:14 JOE: And after you do that kind of there's extraction methods, there is the sieve. you can't participate in one city analysis and then not participate in the other city analysis you have. o do both.

00:25:26 KIM: OK.

00:25:26 JOE: So it's it's sort of the same, the same thing here. You can't. You can't just do one you've got. To do both of them.

00:25:32 KIM: You have to do both and you have to do well in both, correct. A lab could be suspended for T59 in a couple years because of their results of the polymer modified emulsified asphalt. And that would impact their accreditation just for T-95 across the board. It doesn't matter that they got good ratings on the unmodified, emulsified asphalt version.

00:25:57 JOE: That's actually correct. That's something that's. Sort of been in the works for a while. We won't really get on a tangent on that, but because we don't separate the accreditation.  By material type. And that's not just emulsified asphalt. That's that's uh. A lot of different things cements another big one for that, too. It would just show up as a suspension as T59 period. But keep in mind that suspensions from PSP participation only occur if there's no data or low ratings or combination of the two.  On both samples, for two sample rounds in a row. So it takes time for a suspension to actually come through. And as I kind of mentioned earlier.  We don't do a lot of suspensions for almost fine asphalt, so it's not a huge deal. Low ratings are really big issue, but back to your original question, they do have to participate in.  Both all right and so.

00:26:51 KIM: Because we don't have an inventory of extra proficiency samples to resolve accreditation issues for this sample, so it the benefit that they're in both samples because then they can re get reinstated based on their results on the unmodified or no. OK, OK.

00:27:07 JOE: You know if. They if they were suspended due to PME. We wouldn't look at their results from EMS.

00:27:12 KIM: OK, that's the clarification I need. thank you very much once again to our guest, John Malusky, Ryan LaQuay and Joe Williams. Thanks again for being here. August has been a very heavy month for these PSP Insight episodes. So thank you for taking time to join us.

00:27:28 JOHN: No problem, Kim. [JOE and RYAN: Yeah. Kim. ]

[Theme music fades in.]   

00:27:30 ANNOUNCER: Thanks for listening to AASHTO re: source Q & A. If you'd like to be a guest or just submit a question, send us an email at podcast@aashtoresource.org or call Brian at 240-436-4820. For other news and related content, check out AASHTO re:source's social media accounts or go to aashtoresource.org.