This is the Winter 2015 edition of the quarterly BINDER TECHNICIAN NEWS brought to you by the Asphalt Institute.

Ask Mike

Michael T. Beavin
Technical Training Coordinator
Asphalt Institute

Question: My operator is challenged with the BBR creep stiffness single operator precision. M-values are never considered suspect and always within single operator precision limits. Creep stiffness is not about one third of the time.

We have tried: 1. Staggering starting times in the BBR bath to give both samples exactly the same soaking time doesn’t correct this problem. 2. Reheating the pouring can between pouring BBR molds doesn’t correct this problem 3. Running the first or second sample in the BBR did not show any difference as far as high or low values. 4. Creep stiffness has been suspect on both PPA and non-PPA modified asphalts.

What can we be doing to cause a spread of creep stiffness? Could it be an instrument issue?

Mark Homer
Manager of Liquid Asphalt Supply
Ajax Materials Corporation

Answer: Great question, Mark. Our answer should help some other lab rats and honorary lab rats understand more clearly what is going on behind the scenes during BBR testing.

We are not surprised that your m-value results always fall within allowable tolerances because the m-value is independent of geometry. In other words, you could significantly under-pour one of your two beams and expect to get repeatable results between them. I hope I’m not bursting bubbles here but it’s kinda easy to repeat m-value. The published precision statement reflects this with allowable single operator precision at under 3% for d2s (the tightest allowable variability in the PG system).

Stiffness is another matter. Stiffness is inherently more variable since it is very dependent on geometry. It is proportional to the third power of the thickness. Any irregularity in specimen dimensions greatly affect results. Also, any inadvertent deformation during demolding can affect results. Per AASHTO T 313,  Note 14, “…a warped test beam yields a measured stiffness less than the actual stiffness.” So, double check that your demolding procedure is not causing deformation in your test specimens.

An interesting fact about the BBR test is that the industry standard since the implementation of the PG system has been to test a set of two specimens and then average them. The standard has not even mentioned testing the second beam. The original intent when the research was being conducted was to require a set of two beams but it never made it into the standard (the newest update of the ASTM standard has fixed this).

That said, usually two sets of two beams are used to calculate compliance with the published precision statement. Averaging two beams erases some of the variability you may see between each beam. So, in other words, you are probably right in line with everybody else.

Submit your binder question to Mike Beavin and if it is chosen for an edition of Binder Technician News, you will receive a FREE custom t-shirt. Please include your t-shirt size in your email.

Need an NBTC class or recertification? Here are our 2015 dates:

March 10-12, 2015
March 31-April 2, 2015
November 17-19, 2015

We look forward to seeing you in Lexington!

The NBTC goes global

In early November, the National Binder Technician Certification program hopped the Atlantic. Asphalt Institute’s Technical Training Coordinator Mike Beavin joined John D’Angelo in Doha, Qatar to conduct the first NBTC outside of North America. The program was hosted by International Testing Laboratories.

Doha is currently undergoing what is widely considered the most rapid infrastructure growth in the world. Several multi-billion dollar projects are underway and, with the anticipation of the FIFA World Cup in 2022, there is extra urgency to complete this transformation. Projects include skyscrapers that rival the most elaborate in Dubai, a 35-billion dollar light rail system, a 16-billion dollar airport and a 22-billion dollar overhaul of local road/drainage and major highways.

But with the rapid growth, AI’s sponsors recognized that there must be an excellent understanding and implementation of quality control systems. Qatar recently adopted AASHTO M 332, ‘Performance-Graded Asphalt Binder Using Multiple Stress Creep Recovery (MSCR) Test’ and in the last two years, technicians have been practicing the tests associated with the system. There was no consistent way, however, to evaluate their progress. This was about to change. 

Twenty-five individuals attended 1.5 days of lectures covering the M 320 and M 332 specifications. The attendees represented agency, contractors and laboratory technicians and those with the minimum laboratory experience completed written and hands-on examinations.

Like in the U.S., starting in 90s with the NETTCP program and then in 2008 when that program was brought to the rest of the U.S. by the NBTC, the Doha course represented a serious effort by industry and agency to reduce testing variability. Technicians in the U.S., where the PG system and MSCR test were developed, have had years to become familiar with the concepts and techniques. In fact, over three hundred technicians currently hold NBTC/NETTCP certification.

Since 2008, the pass rate has increased from under 50 percent to over 85 percent as word spread that these exams were no-kidding evaluations of proficiency.  Doha candidates that passed the exams would represent the first NBTC certified technicians in the region. Growing pains were inevitable. So, how did it go?

Great news. Two technicians, Jean Khnaizer with ITL and Banji Ibikunle Oluwangbemi (Bemi) with the Arab Center for Engineering Studies (ACES) exceeded the minimum scores. Asphalt Institute would like to welcome them as the first NBTC certified technicians in the Middle East.

We know Jean and Bemi will represent the program well and positively influence the quality of QC/QA testing.

- Mike Beavin


Product review: Brookfield Rotational Rheometer DV3T
In our first 2015 issue, this quarter’s tech tip will be a brief review/recommendation for some new lab equipment that the Asphalt Institute recently acquired.

Christmas came early this year in November, in the form of two brand new rotational rheometers. Anytime we find new equipment that particularly tickles our fancy, we like to share that information with the Binder Technician community, and the Brookfield DV3T is no exception.

While we were plenty happy with the Brookfield Rotational viscometers that we were using, the Brookfield II and III, we had been using them for quite some time and felt it was time to take a closer look at some of Brookfield’s newer models. Now before I start bragging on the DV3T, I want to make it very clear that this is NOT an advertisement for Brookfield. AI is not being compensated for this and additionally we are NOT downgrading any other rotational rheometer/viscometer manufacturers out there.  

With that being said, we are very happy with the new addition to our laboratory family. While there are a ton of features that I could speak in-depth about I’ll stick to a few key points that we find particularly cool.

Now MY favorite thing about the DV3T is the ease and ability to program multiple temperature rotational readings. I don’t know about you all, but here at AI we often run multi-temperature rotational viscosities, and they can really throw a monkey wrench into multi-tasking. With the DV3T, you simply set your temperatures, run the test, and come back when the test is done, as the device has automatically recorded your numbers at the specified target temperatures. For those of you unfamiliar with the multi-temp procedure, this is very helpful on a busy day where you are running around the lab trying to do a million things at once. It is always nice to have one less thing to think about and one less timer going off!

Another really cool feature is the 7-inch touch screen display that really simplifies all the steps leading up to the running of the test. Not that the earlier models were confusing, but the ease of the step-by-step instruction, makes the navigation of the interface quite simple.

“New rheometers represent the most advanced capability in the worldwide market for viscosity and yield stress measurement,” said Bob McGregor, general manager of marketing at Brookfield Engineering Laboratories. “Ease of use is facilitated by new touch screen interface, which has become the standard thanks to the market proliferation of everyday hand held devices, such as smart phones, iPads, etc."

Here is a list of some of the features and benefits of the DV3T.

- Madison Pohl, Asphalt Institute Asphalt Materials Technician

BTN Spotlight

Nicole Corbin, Marketing and Seminar Coordinator, Asphalt Institute
Nicole is our newest team member at the Asphalt Institute. She is a 2013 graduate of the University of Kentucky with a degree in Human Communications.

Nicole's role with NBTC is multi-dimensional. She acts as registrar for each class, coordinates class meals while NBTC students are on campus, prepares the materials for each student (MS-25 manual, handouts, etc.) and helps manage the NBTC official badges.

A native of Bardstown, Kentucky, Nicole is married to Steve and they share their Lexington, Kentucky home with their dogs Gracie and Stuart. If you have questions about NBTC or recertifications you can email her or call her at 859-288-4967.

Learn more about this program at

The Asphalt Institute, in cooperation with the North East Transportation Training and Certification Program (NETTCP) and working with the AASHTO Materials Reference Lab (AMRL) and industry leaders, has developed one consistent, national PG binder technician certification. This map indicates the states that have USERS/PRODUCERS (in yellow), PRODUCERS (in green) and USERS (in brown) who have been nationally certified by the Asphalt Institute’s National Binder Technician Certification program.
Ultimately, the Asphalt Institute would like to see both certified users and producers in every state. There are now 42 states with users and/or producers who are nationally certified by the AI NBTC and the NETTCP programs. Click the map…

Certification: What You Should Know About Training Binder Technicians (free)
Understanding the MSCR Test and its use in the PG Asphalt Binder Specifications (free)

(affordable technology, schedule at your convenience, pause-rewind-understand and email your questions)


Now only $50 in the Asphalt Institute online store. The second printing includes an Appendix on Multiple Stress Creep Recovery (MSCR) testing.
Asphalt Binder Series
(5 - 2 hour sessions)
Recorded Webinars
Part 1 Intro to Asphalt Binders
Part 2 Asphalt Binder Testing & Specifications
Part 3  Asphalt Binder Testing & Specifications (cont.)
Part 4 Asphalt Emulsions, Cutbacks & Air Blown Asphalts
Part 5 Asphalt Binder Modification & Testing Variability

(affordable technology, schedule at your convenience, pause-rewind-understand and email your questions)
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