Karl Zipf DelDOT February 2014 Grading Asphalt Binders with the Multiple Stress Creep Recovery Test AASHTO TP-70 and MP-19 “The Future is Coming” Karl Zipf DelDOT February 2014

WARNING

Brief History of the Test DTFH61-08-H-0003 – Cooperative Agreement between the FHWA and the Asphalt Institute John A. D’Angelo (FHWA) Asphalt Binder ETG Member Companies of the Asphalt Institute – Technical Advisory Committee

The present test methods for asphalt binder grading do not adequately characterize rutting or polymer-modified asphalts (PMA). The current PG System (AASHTO M-320) is blind to modification and requires PG plus tests such as Elastic Recovery to characterize PMA binders.

The PG system was supposed to reduce rutting but over the past decade and a half it has not

The New Asphalt Binder Test Uses the DSR which labs already have. Runs the sample 10 times. Load and relax.

MSCR Test Data The test gives two values which are the basis of the standards, TP-70 and MP-19. Jnr – Nonrecoverable creep compliance for 10 cycles at a creep stress of 3.2 kPa % Average Recovery at a creep stress of 3.2 kPa

The New Asphalt Binder Test

What’s in a Name SHRP (Sharp) – Strategic Highway Research Program ISTEA (Ice Tea) – Intermodal Surface Transportation Equality Act TWG (Twig) – Technical Working Group MSCR (???) – Multiple Stress Creep Recovery

“MASCAR” Sounds like NASCAR

“Massacre” Like in the Boston Massacre

“Mascara” Both asphalt and mascara are black

“Muskrat” Multiple Stress Creep Recovery Test

Jnr Limits are Based on Rut Data The Jnr (Nonrecoverable Compliance) correlated to rut depth in the ALF track, field studies and lab tests. The Jnr will used to determine the binder grade. Jnr works for both modified and non-modified binders.

MSCR % Recovery & Modification Many processes will stiffen and binder but not all make them elastic. The % Recovery is used to characterize the elasticity from polymer modification. A polymer curve was developed based on data from available PMA binders.

Polymer Modification Curve Currently in TP-70, will move to MP-19

So Far So Good Jnr % Recovery So how do you grade a binder? Two key values for the MSCR test These will determine the binder grade and whether it can be called a PMA binder. Jnr % Recovery So how do you grade a binder?

Like PG System, Grade Based on LTPP Climate Temperature

Looks Familiar USDA Plant Hardiness Zone Map

Northeast States LTPP High, Low and USDA

M-320 & MSCR Nomenclature Right now it now it looks like the PG System The BIG change is that everything is based on the LOCAL high temperature environment. Our environment is 64C and our standard grade, like the PG system is PG 64-22. Other grades, PG 70, and PG 76 will be tested at 64C as PG 64(something), based on the Jnr. Binder name becomes state/region dependent.

MSCR and Low Temperature The low temperature tests and nomenclature will not change with MSCR. It still uses the BBR results. The mid temperature criteria, the 8 mm DSR test, will have 6000 kPa as a cutoff for the stiffer grades, since for DelDOT the test temp will be 25C.

MP-19 Grades at 64C Jnr = 2.0 – 4.0 = PG 64S-22 “Standard” = PG 64-22 Jnr = 1.0 – 2.0 = PG 64H-22 “Heavy” = PG 70-22 Jnr = 0.5 – 1.0 = PG 64V-22 “Very Heavy” = PG 76-22 Jnr = 0.25 – 0.5 = PG 64E-22 “Extreme” = PG 76-22 Note MP-19 uses “High” & “Heavy” interchangeably Standard “S” = traffic < 10 million ESALs, > 70 km/h Heavy “H” = traffic 10-30 million ESALs, 20-70 km/h Very Heavy “V” = traffic > 30 million ESALs, < 20km/h Extreme “E” > 30 million ESALs, < 20km/h, toll plazas

Polymer Curve & DelDOT Data

Where the New Grades Fall at 64C

When Will DelDOT See MP-19? The FHWA is pushing the MSCR test ASAP. The Asphalt Institute is pushing the MSCR test. The NEAUPG (Northeast Asphalt User-Producer Group) is reviewing a limited regional implementation for maybe 2014. NEAUPG will be polymer curve in 2014, and non-PMA in a future year. SEAUPG will consider it in 2015, central USA later, and west coast probably not at all. National implementation date is unknown.

DelDOT M-320 vs MP-19 Grades PG 58-28 = PG 58S-28, Jnr 2.0 – 4.5 58C PG 70-22 = PG 64H-22, Jnr 1.0 – 2.0 64C No Grade = PG 64V-22, Jnr 0.5 – 1.0 64C For 2014 ? PG 76-22 = PG 64E-22, Jnr < 0.5 64C and meet polymer elasticity curve.

DelDOT and PG 76-22 as MSCR 64V 64E

NEAUPG & PMA From Maine to Maryland there will probably be two standard grades, PG 58S & PG 64S. NYDOT will switch over all grades around Sept 2014 to MP-19.

MSCR and RAP Like the PG System, M-320 the MSCR spec, MP-19 is based on 100% virgin binders. RAP is stiff, Jnr 0.1 - 0.2, but not elastic so will fail the polymer curve. RAP affects the low temperature properties, and these rules have not changed, and it is the low temperature where one sees failure.

August 2014 The MSCR Test AASHTO TP-70 will be a full standard AASHTO T-350 The MSCR Binder Grading AASHTO MP-19 will be a full standard, AASHTO M-322.

The End (Not really. There will probably be more next year.) Questions?

Implementing a New Standard