Grading asphalt binders with the, multiple stress creep recovery test, AASHTO TP 70 and MP 19

Grading Asphalt Binders with the Multiple Stress Creep Recovery TestAASHTO TP-70 and MP-19 “The Future is Coming” Karl ZipfDelDOT February 2014... Brief History of the Test• DTFH61-08-H-

Grading Asphalt Binders with the Multiple 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

• Sounds like NASCAR

• Like in the

Boston

Massacre

• Both asphalt and mascara are black

• 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 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

• 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

DelDOT and PG 76-22 as MSCR

64V

64E

NEAUPG & PMA

• 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,

The End

(Not really There will probably be

more next year.)

Questions?

Implementing a New Standard