PERFROMANCE EVALUATION OF ASPHALT PAVEMENT
MIXES IN IDAHO CONTAINING HIGH PERCENTAGES FOR
RECYCLED ASPHALT PAVEMENT (RAP)
Haifang Wen, PhD, PE Kun Zhang, Graduate Student Washington State University
Fouad Bayomy, PhD, PE Ahmed Muftah, Graduate Student
University of Idaho
Outline • Background • Objectives • Laboratory Characterization • Findings
Outline • Background • Objectives • Laboratory Characterization • Findings
Background • Benefits of using RAP in HMA
– Economics • Aggregates • Binder
– Environment • Resources • Petroleum • Landfill • Energy • Emission
Background • Status of the use of RAP in HMA
Copeland et al. 2011
Mix Design-Virgin Binder Selection
• ITD Binder Adjustment
– Replacement <=17%. No adjustment
– 17%<Replacement<= 30. One grade lower
– Replacement>30 %. Blending chart. – Based on assumption of complete blending between RAP
binder and virgin binder
Dynamic Modulus
• Dynamic modulus increased with increasing RAP
percentage, and RAP significantly affects dynamic modulus values at intermediate and high temperature (Li 2008, McDaniel 2012, Qazi 2011)
Performance-Rutting
• Consensus Conclusion:
– Rutting resistance increased as the increase of
percent of RAP (Hajj 2009, Qazi 2011, Santos 2010, Yu 2010, Colbert 2012)
– Aged RAP binder increase the stiffness of mixture
8
Fatigue Cracking
• Most studies show that RAP mixtures had reduced fatigue life or more brittle behavior (Huang 2011, Shu 2008, Yu 2010, NCHRP 9-12)
• A few studies, however, showed that mixtures with RAP had better fatigue life (Santos 2010, Hajj 2009, McDaniel 2012)
• Fatigue life of stiffer mixes depends on the thickness of layer (Sousa 1998, Hassan 2009)
Thermal Cracking
• Fracture Energy (Li 2008) – Decrease as RAP content increased, indicating lower low-
temperature fracture resistance • Fracture temperature (Hajj 2011)
– Thermal stress retained specimen test (TSRST) test – similar TSRST fracture temperature between 0 and 15%
RAP mixes – several degree warmer for 50% RAP mixes , indicating
decreased thermal cracking resistance • Using soft binder could help improve thermal
cracking resistance
Moisture Susceptibility
• Mixtures with RAP could have acceptable resistance
to moisture damage, or addition of antistripping
additive could help mixtures with RAP gain TSRs
above 0.80 (Hajj 2009, NCHRP 9-46, Yu 2010, Loria 2011)
11 *www. pavementinteractive.com
Background • We can not wait for 20 years to see the
performance • Need to determine the performance before
pavement with high RAP percentage is built • Key is to select materials properties from lab
to relate to field performance for performance evaluation and also mix design
Outline • Background • Objectives • Laboratory Characterization • Findings
Objective
• Verify the guideline by ITD on the use of RAP in HMA to lead to same performance in the laboratory
• Evaluate the effect of RAP on pavement performance
Outline • Background • Objectives • Laboratory Characterization • Findings
Material Procurement
• Plant Loose Mixes and Field Cores – US95 Garwood to Sagle, 30% RAP by binder
replacement • Lab Mixes
– Binder: • PG58-28 (Control), PG52-34
– Aggregates: • Nominal Maximum Size is 19mm
RAP Characterization
• Binder Content
• RAP Aggregate Gradation
• Bulk Specific Gravity of RAP Aggregate
• PG of Extracted RAP Binder
RAP Characterization
• Fractionated
– Coarse RAP and fine RAP are separated by No.4
Screen
• 0.53:0.47 for the North RAP
• Recombined after homogenization in a
concrete mixer
RAP Binder Content
• Ignition Oven (AASHTO T308) • Chemical Extraction (AASHTO T164 )
4.9% 4.5%
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
North RAP
IgnitionChemical
Gradation of RAP Aggregate
• AASHTO T30 “Mechanical Analysis of Extracted Aggregate”
0102030405060708090
100
% P
assi
ng
Sieve Size (mm)
Gradation of North RAP Aggregate
Ignition Oven Method
Chemical Method
19 12.5 9.5 4.75 2.36 0.075 0.6 1.18
Bulk Specific Gravity of RAP Aggregate • Ignition Oven : AASHTO T308
– Coarse Aggregate: AASHTO T85 – Fine Aggregate: IT 144
North RAP Aggregate 1 2 3 Average Std COV
Coarse RAP aggregate 2.604 2.604 2.611 2.606 0.004 0.15%
Fine RAP aggregate 2.618 2.628 2.635 2.627 0.009 0.33%
Combined 2.619
Results of PG of Extracted Binder
• Chemical Extraction and Recovery: – AASHTO T164-11 & AASHTO T170
• RAP Binder: PG 75.8-23.6
PG of Recovered North RAP binder
1 2 3 Average Std COV
High Temperature 76.9 74.9 75.5 75.8 1.0 1.3%
Low Temperature -22.7 -24.6 -23.6 -23.6 1.0 4.2%
Mix Design
• Lab Mixes
– Four different RAP percentages
• 0, 17, 30, and 50% (N0, N17, N30 and N50)
– Duplicate field mix in terms of aggregate gradation
• US-95, Garwood to Sagle, Chilo STG
– Class of Mixture
• 3/4’’, SP5, Traffic 10-30 (ESALs)
PG of Blended Binder for Mixes
% RAP Virgin Binder RAP binder Blended Binder Target PG of binder
0 58-28 ----- 58-28
58-28 17 58-28
75.8-23.6
61.0-27.3
30 52-34 59.1-30.9
50 52-34 (40-34) 63.9-28.8
Assuming 100% blending between the RAP binder and virgin binder
Results of Mixes 4.9
4.5
4.8
4.7
4.8
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
Bind
er C
onte
nt (%
)
Optimum Binder Content
N0 N17 N30 N50 Field Mixes
14.3
13.2
13.7
13.3
14
12.6
12.8
13
13.2
13.4
13.6
13.8
14
14.2
14.4
VM
A (%
)
VMA
N0 N17 N30 N50 Field Mixes
72
69
71 71 71
60
65
70
75
80
VFA
(%)
VFA
N0 N17 N30 N50 Field Mixes
1.3
1.5 1.4 1.4 1.4
0.6
0.8
1
1.2
1.4
1.6
1.8
DP
DP
N0 N17 N30 N50 Field Mixes
Lab Performance Evaluation
• Modulus • Rutting • Fatigue Resistance • Low Temperature Thermal Cracking
Dynamic Modulus Test (E*)
• Sample Preparation for E* – Mixing – Short term aging 140 F, 16hour aging – 2-2.5 hours aging at compaction temperature – Compaction – Core and cutting with air voids within 6.5%-7.5% – Testing temperatures ( 40o F, 70o F, 100o F, 130o F) – Loading frequencies(0.1Hz, 0.5Hz,1Hz, 5Hz,
10Hz, 25Hz).
E*- Master Curves-Mixes
1000
10000
100000
1000000
10000000
0.00001 0.01 10 10000
Dyna
mic
Mod
ulus
(psi
)
Frequency (Hz)
Dynamic Modulus Master Curves at 70° F Reference Temperature of the North
Mixes
0% RAP
17% RAP
30% RAP
50% RAP
% RAP Virgin Binder
0 58-28
17 58-28
30 52-34
50 52-34 (40-34)
Gyratory stability (GS)-Rutting
R = the resultant ram force E = the average eccentricity for a given gyration cycle A = the sample cross section, and h = the sample height at any gyration cycle.
0
5
10
15
20
25
0 50 100 150
Air
Void
s, %
N
Air Voids vs. N
Gyratory stability (GS) - Rutting
% RAP Virgin Binder
0 58-28
17 58-28
30 52-34
50 52-34 (40-34) 11
11.5
12
12.5
13
13.5
14
14.5
0% 17% 30% 50%
GS
(Kn.
m)
%RAP
Flow Number Rutting • Laboratory Tests
– Rutting (flow number) – repeated load @ high temperature
*NCHRP Report 465
Flow Number - Rutting % RAP Virgin Binder
0 58-28
17 58-28
30 52-34
50 52-34 (40-34)
0
100
200
300
400
500
600
700
0% 17% 30% 50%
Aver
age
Flow
Num
ber
RAP %
Fatigue Performance Test • For fatigue, test methods in the lab can include
– Stiffness
– Indirect tensile strength
– Beam fatigue
Fatigue Resistance • Long term aging
– 5 days at 185ºF • Test temperature
– Temperature: 68ºF – Displacement Control: 2inch/min
• Properties – Fracture Work Density – Vertical Failure Deformation
Fracture Work Density Bottom-up fatigue cracking - fracture work from Indirect
Tensile test at 68ºF (Wen et al. 2011)
0
50000
100000
150000
200000
250000
70,000 90,000 110,000 130,000 150,000Num
ber
of P
asse
s to
3% C
rack
ing
Fracture Work Density, Pa
Vertical Failure Deformation Top-down cracking – vertical failure deformation (Wen
et al. 2013) 12 out of 15 pair pavements match
Vertical Failure Deformation
Fatigue Results
% RAP Virgin Binder
0 58-28
17 58-28
30 52-34
50 52-34 (40-34)
0.0667
0.0591
0.0728 0.0644
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
Vert
ical
Def
orm
atio
n at
Pea
k Lo
ad (I
nch)
N0 N17 N30 N50
14.78 13.66
12.32 13.81
0
2
4
6
8
10
12
14
16
18
Wor
k De
nsity
(Psi
)
N0 N17 N30 N50
5.3 Low Temperature Thermal Cracking • AASHTO T322
– “Standard Method of Test for Determining the Creep Compliance and Strength of Hot-Mix Asphalt (HMA) Using the Indirect Tensile Test Device”
• IDT Strength Test – Temperature: 14ºF
• Fracture Work Density Correlates with Thermal Cracking – Wen et al. 2013, 15 out of 19 pair pavements match
Results of Low Temperature Cracking
% RAP Virgin Binder
0 58-28
17 58-28
30 52-34
50 52-34 (40-34)
148
81
124
104
0
20
40
60
80
100
120
140
160
180
200
Wor
k D
ensi
ty (P
si)
N17 N30 N50 N0
480.41
601.25
483.13
580.37
0
100
200
300
400
500
600
700
800
IDT
Str
engh
t (P
si)
N0 N17 N30 N50
Outline • Background • Objectives • Laboratory Characterization • Findings
Findings • With the increase of RAP percentage
– Stiffness increases – Rutting resistance increases – Fatigue cracking resistance is not affected – Low temperature cracking resistance is affected
• The low temperature cracking resistance can be improved by change of PG grade or mix design
• Further verification is needed (South Idaho Mix)
Acknowledgements The team would like to thank ITD for sponsoring this research and their support during the study
Washington Center for Asphalt Technology (WCAT)
Haifang Wen, PhD, PE, Director Assistant Professor
Washington State University
Background • Established through partnership between
– Washington State Department of Transportation (WSDOT),
– Washington Asphalt Paving Association (WAPA), and
– Washington State University (WSU) • Funding also contributed by National Science
Foundation (NSF) • Website: wcat.cee.wsu.edu
Members
Graduate Students
WCAT Activities • Education
– Undergraduate and graduate students • Industry services
– Mix design and verification – Studies
• Research and development – NCHRP 09-49A, 04-36 – FHWA EAR – National Science Foundation – WSDOT, ITD, WisDOT, Counties – University Transportation Centers – Industries
Laboratory Experiments • WCAT is AASHTO accredited
– Mix design – Mix verification
• Binder Tests • Extraction and recovery • Asphalt Content of Compacted Bituminous Mixtures using Ignition
Oven or Solvent • Dynamic Shear Rheometer • Bending Beam Rheometer • Rolling Thin Film Oven • Pressure Aging Vessel • Rotational Viscometer (Brookfield)
Laboratory Experiments • Mix performance tests
– Dynamic Modulus Test - stiffness – Static Creep Test (Flow Time) - rutting – Repeated Load Test (Flow Number) – rutting – Indirect Tensile Test – fatigue and thermal
cracking – Modified Lottman – moisture damage – Studded tire simulator
Thanks!
Questions?
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