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Asphalt Modifiers: Warm Mix, Polyphosphoric Acid, and Polymers Tim Clyne, MnDOT MnROAD Research Conference October 4, 2011
Asphalt Modifiers:
Warm Mix, Polyphosphoric
Acid, and Polymers
Tim Clyne, MnDOT
MnROAD Research Conference
October 4, 2011
Presentation Topics
Intro to Binder Modification
Types of modification used at MnROAD
Dry Additives (Mineral Fillers)
Polymers
SBS, Elvaloy
Polyphosphoric Acid
Warm Mix Asphalt
Pavement Lab & Field Performance
Summary & Conclusions
Why Modified Asphalt?
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
0 5 10 15 20
Me
dia
n N
o. o
f T
ran
s. C
rac
ks
pe
r 3
05
m
(pe
r 1
00
0 f
t.)
BAB Age, years
PG XX-34 Avg.
1971 to 1980
1981 to 1990
1991 to 1994
1995 to 1999
2 cracks/1000’
at age 7!
Bituminous over Concrete
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9 10
Pavement Age, Years
Avera
ge T
ran
svers
e C
rackin
g, L
F
58-34
58-28
64-28
64-22
Basics of Binder Modification
Start with soft binder grade
Low temperature
Add modifier to increase high temperature grade
Without compromising low temperature grade
PG 49-34 PG 64-34
Types of Modification at MnROAD
Dry Additive
PG 52-34 (2006)
Polymers
SBS
Elvaloy
PG 58-34, 64-34, 70-28 (1999, 2004, 2007, 2008, 2010)
Polyphosphoric Acid
PG 58-34 (2007)
Warm Mix Asphalt
Evotherm 3G
PG 58-34 (2008)
1999 Superpave Study
PG 58-28, 58-34, 58-40
Slightly different rutting performance
Vastly different cracking performance
2006 PG 52-34 on Mainline
Major cracking in driving
lane due to instrumentation
and age
6” HMA + 33” Class 4
1.5” Mill & Inlay
PG 52-34, Level 2
Superpave, no RAP
Amazing Performance
3.6 Million ESALs after 5 years
Cracking returned, but low severity
Minimal rutting
Polyphosphoric Acid Study
Field validation of previous FHWA (and other) laboratory work
More cost-effective than polymers
FHWA, Innophos, ICL Performance Products, Mathy Construction, Marathon, Paragon, Dupont, Western Research Institute
Four different PPA binders (PG58-34):
PPA
PPA + SBS
PPA + Elvaloy
SBS
100
1000
10000
1.0E-03 1.0E-01 1.0E+01 1.0E+03
Reduced Freuency (Hz)
|E*|
(M
Pa
)
PPA
SBS + PPA
SBS
PPA + Elvaloy
Dynamic Modulus
Lab Cracking Performance
-1,500
-1,000
-500
0
500
1,000
1,500-30,000
-20,000
-10,000
0
10,000
20,000
30,000
PPA Only SBS+PPA SBS Only PPA+Elvaloy 500
mic
rost
rain
fati
gue
life
300
mic
rost
rain
fati
gue
life
VECD Fatigue Life at 300εμ
VECD Fatigue at 500εμ
≠≠ ≈
Fatigue
Fracture
Field Rutting Data
PPA Project Status
TRB Circular from 2009 Workshop
Several published papers from study
TRB, AAPT, ASCE Journal, etc.
Numerous conference & workshop presentations
Funding is complete
Final report due in 2012
PPA + Polymer generally performed better than
either modifier alone
No Big Deal!
Warm Mix Asphalt
6 Cells on Mainline
Control on LVR
New construction (2008)
Elvaloy
PPA
Evotherm 3G
Lubricator
Anti-strip
Mix Design Requirements
Wear and Non-Wear
12.5 mm NMAS
Traffic Level 4
PG 58-34
20% RAP from MnROAD
No requirements for WMA technology
Hardrives chose REVIX (Evotherm 3G)
Construction Lessons Learned
More lab work needed at mix design to determine
compaction temperature range
Definite energy savings
Appears as though fumes/emissions were less
Equal density appears to be achievable with equal or
less effort
No Big Deal!
Moisture Damage Potential
85.6%83.4%
0
1
2
3
4
5
6
7
8
9
wear non-wear
Str
en
gth
, p
si
70.0%
75.0%
80.0%
85.0%
90.0%
95.0%
100.0%
Ten
sile S
tren
gth
Rati
o
Dry
Wet
TSR
WMA Ride Performance
WMA Rutting Performance
Spring 2011
WMA Field Performance (2)
1 transverse crack in 5 test sections
Over instrumentation area (inadequate compaction)
25% reflective cracking on 3” WMA overlay
So far, so good
Great, But What Does It Cost?
Binder Grade Price per Liquid Ton
PG 58-28 $410
PG 64-28 $530
PG 58-34 $555
PG 64-34 $585
Summary
Modified binders have shown excellent performance
at MnROAD
Minimal cracking and rutting
Similar to MnDOT network performance
Better than neat binders
SBS and Elvaloy provide great polymer modification
PPA modification is an acceptable alternative at
(generally) a lower cost
Even dry additive works at times
Life Cycle Cost?
