high reclaimed asphalt pavement use in asphalt mixtures
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High Reclaimed Asphalt Pavement Use in Asphalt Mixtures. Canadian User/Producer Group for Asphalt Moncton, Canada November 15, 2009 Audrey Copeland and Gerry Huber FHWA and Heritage Research. Defining High RAP. R eclaimed A sphalt P avement Removed and/or reprocessed pavement - PowerPoint PPT PresentationTRANSCRIPT
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U.S. Department of TransportationFederal Highway Administration
High Reclaimed Asphalt Pavement Use in Asphalt Mixtures
Canadian User/Producer Group for AsphaltMoncton, Canada
November 15, 2009
Audrey Copeland and Gerry HuberFHWA and Heritage Research
U.S. Department of TransportationFederal Highway Administration
Defining High RAP• Reclaimed Asphalt Pavement
• Removed and/or reprocessed pavement materials containing: ~ binder (5%)~ aggregates (95%)
High RAP is defined as more than 25% RAP by weight of mix.
U.S. Department of TransportationFederal Highway Administration
RAP Efforts
• State of the Practice
• Primary Barriers and Remaining Challenges for Increased RAP Use
• National Efforts to Overcome Challenges
U.S. Department of TransportationFederal Highway Administration 4
States that Permit more than 25% RAP
U.S. Department of TransportationFederal Highway Administration
States that Use More than 20% RAP in HMA Layers
CA
AZ
CO
NM
TX
OK AR
LA
MO KY
AL GA
FL
VA
OH
MI
VTAK
MT
NV
MEWA
OR
UTKS
IDWY
ND
SD
MN
NE
WI
IAIL IN
MS
TNSC
NC
WV
PA
NY
CTNJDEMD
DC
MANH
PR
HI
RI
All layers (20% or more)Base and Intermediate layers onlyBase layer onlyDo not use more than 20% RAP
U.S. Department of TransportationFederal Highway Administration
So, why does < half of the nation use < 20% RAP?
• Blended virgin and RAP binder qualities especially for high RAP mixes and polymer modified binders
• Stiffening of the mix from high RAP quantities and resulting cracking performance.
6
U.S. Department of TransportationFederal Highway Administration
Other “Roadblocks”
• Presence of dust
• Consistency/variability of RAP
• Lack of Quality Control (QC) by contractor
• Durability, especially in the surface layers– Raveling
7
U.S. Department of TransportationFederal Highway Administration
Things are improving…
• Since 2007:– 21 States have increased amount of RAP
permitted
– 23 States now have experience with high RAP mixes
– 11 States have experience with high RAP and Warm Mix Asphalt mixes
U.S. Department of TransportationFederal Highway Administration 9
HMA Asphalt Pavement Recycling Expert Task Group
Advance the use of RAP in asphalt paving applications by providing highway agencies with critical information regarding the use of RAP, technical guidance on high-RAP projects, and direction on research activities.
The members consist of representatives from highway agencies, industry, and academia.
Website: www.moreRAP.us
U.S. Department of TransportationFederal Highway Administration 10
Current Guidelines• AASHTO M 323 Standard Specification
for SuperpaveTM Volumetric Mix Design
• Based on significant blending between virgin and RAP binder• Effects of plant production unknown• Calls for virgin binders that may be more expensive, hard to get• Blending chart analysis is time-consuming!
Recommended Virgin Asphalt Binder Grade Percent (%) RAPNo change in binder selection < 15Select virgin binder grade one grade softer than normal 15 – 25
Follow recommendations from blending charts > 25
U.S. Department of TransportationFederal Highway Administration 11
Issues to Consider when Increasing RAP
• Additional Processing & Quality Control (QC)
• Characterizing RAP
• Changing Binder Grade
• Mix Design
• Blending/Co-mingling of Virgin and RAP Binder
• Performance
U.S. Department of TransportationFederal Highway Administration
• Mill Intelligently
• Processing RAP
• Stockpile Management
Processing and Quality Control
U.S. Department of TransportationFederal Highway Administration
Characterizing RAP for High RAP Use
• Asphalt Content– RAP binder contribution, reduce virgin binder required– Ignition oven or solvent extraction
• Performance Grade of RAP binder– Estimate blended binder properties– Evaluate stiffness of RAP– Recovered Binder is unaged
• RAP Aggregate Gradation– Ensure quality material– Determining Gsb, Gse of RAP aggregate – significant effect
on VMA and asphalt content– Combined aggregate properties must meet consensus
requirements
U.S. Department of TransportationFederal Highway Administration 1414
Investigation of Properties of Plant Produced RAP Mixtures
• Assess current guidelines for RAP usage by determining low and high temperature properties of plant-produced HMA with varying RAP contents and virgin binder grades
• Investigate virgin and RAP binder blending during plant production
U.S. Department of TransportationFederal Highway Administration
EXPERIMENTAL DESIGN
Reclaimed Asphalt Pavement
Binder Grade 0% 15% 25% 40%
PG 58-28 X XPG 64-22 X X X X
U.S. Department of TransportationFederal Highway Administration
0.0001
0.0010
0.0100
0.1000
1.0000
10.0000
100.0000
1000.0000
10000.0000
0.001 0.010 0.100 1.000 10.000 100.000 1000.000 10000.000
Log Reduced Frequency, Hz
Log
Mod
ulus
, MPa
mix |E*| |G*|b,rec |G*|b,rap PG64
Phase I, PG64-22, 40% RAP
U.S. Department of TransportationFederal Highway Administration
0.0001
0.0010
0.0100
0.1000
1.0000
10.0000
100.0000
1000.0000
10000.0000
0.001 0.010 0.100 1.000 10.000 100.000 1000.000 10000.000
Log Reduced Frequency, Hz
Log
Mod
ulus
, MPa
mix |E*| |G*|b,rec |G*|b,rap PG58
Phase I, PG58-28, 40% RAP
U.S. Department of TransportationFederal Highway Administration
Phase I Conclusions
• RAP has less impact than expected.• Higher RAP contents not significantly
stiffer than virgin mix.• Binder did not stiffen linearly with
increasing RAP content.• Dropping grade to PG58-28 not
necessary.
U.S. Department of TransportationFederal Highway Administration
Phase II – Mixture Test Methods
• Dynamic Modulus, E*– Master Curves
• Indirect Tensile Test (IDT) Creep & Compliance– Critical Cracking Temperature
• IDT at high temperatures– Relaxation Modulus
• Complex Modulus, G* and d, of Recovered Binder
U.S. Department of TransportationFederal Highway Administration
Phase 2 Contractor A, PG 64-22 Mixes
100
1000
10000
100000
1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06
Log
|E*|,
MPa
Log Reduced Frequency, Hz
PG64-22
MixA (0%0 RAP)
MixB (15% RAP)
MixC (25% RAP)
MixD (40% RAP)
U.S. Department of TransportationFederal Highway Administration
Contractor A, 64-22 vs 58-28
100
1000
10000
100000
1.E-04 1.E-02 1.E+00 1.E+02 1.E+04
Log
|E*|,
MPa
Log Reduced Frequency, Hz
PG64-22 versus PG58-28
MixC (25% RAP)
MixE (25% RAP)
MixD (40% RAP)
MixF (40% RAP)
U.S. Department of TransportationFederal Highway Administration
Contractor B, PG64-22 Mixes
100
1000
10000
100000
1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06
Log
|E*|,
MPa
Log Reduced Frequency, Hz
PG64-22
MixA (0%0 RAP)
MixB (15% RAP)
MixC (25% RAP)
MixD (40% RAP)
U.S. Department of TransportationFederal Highway Administration
Contractor B, PG64-22 vs 58-28
U.S. Department of TransportationFederal Highway Administration
Contractor C, PG64-22 Mixes
100
1000
10000
100000
1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06
Log
|E*|,
MPa
Log Reduced Frequency, Hz
PG64-22
MixA (0%0 RAP)
MixB (15% RAP)
MixC (25% RAP)
MixD (40% RAP)
U.S. Department of TransportationFederal Highway Administration
Contractor C, PG64-22 vs 58-28
100
1000
10000
100000
1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06
Log
|E*|,
MPa
Log Reduced Frequency, Hz
PG64-22 versus PG58-28
MixC (25% RAP)
MixE (25% RAP)
MixD (40% RAP)
MixF (40% RAP)
U.S. Department of TransportationFederal Highway Administration
Contractor D, PG64-22 Mixes
100
1000
10000
100000
1.E-04 1.E-02 1.E+00 1.E+02 1.E+04
Log
|E*|,
MPa
Log Reduced Frequency, Hz
PG64-22
MixA (0%0 RAP)
MixB (15% RAP)
MixC (25% RAP)
MixD (40% RAP)
U.S. Department of TransportationFederal Highway Administration
Contractor D, PG64-22 vs 58-28
100
1000
10000
100000
1.E-04 1.E-02 1.E+00 1.E+02 1.E+04
Log
|E*|,
MPa
Log Reduced Frequency, Hz
PG64-22 versus PG58-28
MixC (25% RAP)
MixE (25% RAP)
MixD (40% RAP)
MixF (40% RAP)
U.S. Department of TransportationFederal Highway Administration
Indirect Tensile Test
Low temperature creep compliance test 0, -10, -20C
Low temperature strength test -10°C
Determine stiffness, strength, and critical cracking temperature, Tc
U.S. Department of TransportationFederal Highway Administration
Contractor A - IDT Strength
RR-A RR-B RR-C RR-D RR-E RR-F2000
2400
2800
3200
3600
4000
-44
-38
-32
-26
-20
Strength
Temperature
Mixes
Stre
ngth
, kPa
Pvmt. C
racking Tem
perature, °C
0% 15% 25% 40% 25% 40% PG64-22 PG58-28
U.S. Department of TransportationFederal Highway Administration
Contractor A - IDT Stiffness
RR-A RR-B RR-C RR-D RR-E RR-F10
14
18
22
26
30
-44
-38
-32
-26
-20Stiffness
Temperature
Mixes
Stiff
ness
, GPa
Pvmt. C
racking Tem
perature, °C
0% 15% 25% 40% 25% 40% PG64-22 PG58-28
U.S. Department of TransportationFederal Highway Administration
Contractor B - IDT Strength
JH-A JH-B JH-C JH-D JH-E JH-F2000
2500
3000
3500
-26
-20
-14
Strength
Temperature
Mixes
Stre
ngth
, kPa
Pvmt. C
racking Tem
perature, °C
0% 15% 25% 40% 25% 40% PG64-22 PG58-28
U.S. Department of TransportationFederal Highway Administration
Contractor B - IDT Stiffness
JH-A JH-B JH-C JH-D JH-E JH-F10
14
18
22
26
30
-44
-38
-32
-26
-20Stiffness
Temperature
Mixes
Stiff
ness
, GPa
Pvmt. C
racking Tem
perature, °C
0% 15% 25% 40% 25% 40% PG64-22 PG58-28
U.S. Department of TransportationFederal Highway Administration
Contractor C - IDT Stiffness
EB-A EB-B EB-C EB-D EB-E EB-F20
30
40
-20
-14
Stiffness
Temperature
Mixes
Stiff
ness
, GPa
Pvmt. C
racking Tem
perature, °C
0% 15% 25% 40% 25% 40% PG64-22 PG58-28
U.S. Department of TransportationFederal Highway Administration
Contractor D - IDT Strength
PB-A PB-B PB-C PB-D PB-E PB-F2500
3000
3500
4000
-26
-20
-14
Strength
Temperature
Mixes
Stre
ngth
, kPa
Pvmt. C
racking Tem
perature, °C
0% 15% 25% 40% 25% 40% PG64-22 PG58-28
U.S. Department of TransportationFederal Highway Administration
Contractor D - IDT Stiffness
PB-A PB-B PB-C PB-D PB-E PB-F10
15
20
25
-26
-20
-14
Stiffness
Temperature
Mixes
Stiff
ness
, GPa
Pvmt. C
racking Tem
perature, °C
0% 15% 25% 40% 25% 40% PG64-22 PG58-28
U.S. Department of TransportationFederal Highway Administration
Phase II Summary
• Dynamic Modulus results seem to agree with Phase I results – RAP has less impact than expected.– Higher RAP contents not significantly stiffer than
virgin mix.– Dropping grade to PG58-28 may not be necessary.
• Critical cracking temperatures are mixed bag, but also indicate that binder grade changes may not be necessary.
U.S. Department of TransportationFederal Highway Administration 3737
High RAP Mix Design
• NCHRP 9-46 Mix Design and Evaluation Procedure for High Reclaimed Asphalt Pavement Content in Hot Mix Asphalt
• Objective: Develop mix design method and specification for HMA containing up to 50% RAP.
U.S. Department of TransportationFederal Highway Administration
Evaluating RAP Performance
• Long Term Pavement Performance SPS-5 sections– Virgin– 30% RAP– Milled and non-milled surface– 50 and 125 mm thick– Oldest is over 17 years
at Auburn University
U.S. Department of TransportationFederal Highway Administration
SPS-5 Project Locationsat Auburn University
U.S. Department of TransportationFederal Highway Administration
40
Fatigue Cracking
29%
10%61%
Virgin performedsignificantly betterthan RAP
RAP performedsignificantly betterthan Virgin
Differencebetween Virginand RAPinsignificant
at Auburn University
U.S. Department of TransportationFederal Highway Administration
41
Longitudinal Cracking
15%
10%
75%
Virgin performedsignificantly betterthan RAP
RAP performedsignificantly betterthan Virgin
Differencebetween Virginand RAPinsignificant
at Auburn University
U.S. Department of TransportationFederal Highway Administration
42
Block Cracking
3% 1%
96%
Virgin performedsignificantly betterthan RAP
RAP performedsignificantly betterthan Virgin
Differencebetween Virginand RAPinsignificant
at Auburn University
U.S. Department of TransportationFederal Highway Administration
43
Raveling7%
15%
78%
Virgin performedsignificantly betterthan RAP
RAP performedsignificantly betterthan Virgin
Differencebetween Virginand RAPinsignificant
at Auburn University
U.S. Department of TransportationFederal Highway Administration
So….What’s The Take-away?• Experience and data supports the proper use
of high RAP can provide similar or better performance than virgin mixes, but available plant and field data is sporadic.
• On-going research results indicate high RAP use is possible without adversely affecting performance.
• More studies are needed with emphasis on plant mixtures and field performance.
U.S. Department of TransportationFederal Highway Administration
Thank you!