Grading Asphalt Binders with theMultiple Stress Creep Recovery Test

AASHTO TP-70 and MP-19

“The Future is Coming”

Karl ZipfDelDOT

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

• 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 StatesLTPP 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 64-22 = PG 64S-22, Jnr 2.0 - 4.5 64C• PG 64-28 = PG 64S-28, Jnr 2.0 – 4.5 64C • 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