MSCR Test

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 nonmodified 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
Elastic Response TP-70 X2.1 Curve
90
80
70
y = 29.37x-0.263
% Recovery 3.2 kPa
60
50
Passing Percent Recovery
40
30
Failing Percent Recovery
20
10
0
0
0.2
0.4
0.6
0.8
1
Jnr 3.2 kPa
1.2
1.4
1.6
1.8
2
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.
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 UserProducer 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