balanced/performance-engineered asphalt mixture design...
TRANSCRIPT
Balanced/Performance-Engineered Asphalt Mixture Design
Thursday, November 1, 20182:00-3:30 PM ET
TRANSPORTATION RESEARCH BOARD
The Transportation Research Board has met the standards and
requirements of the Registered Continuing Education Providers Program.
Credit earned on completion of this program will be reported to RCEP. A
certificate of completion will be issued to participants that have registered
and attended the entire session. As such, it does not include content that
may be deemed or construed to be an approval or endorsement by RCEP.
Purpose
Discuss balanced/performance-engineered asphalt mixture design.
Learning Objectives
At the end of this webinar, you will be able to:
• Describe the concept of balanced/performance-engineered asphalt mixture design
• Identify the potential benefits of implementing balanced/performance-engineered mixture design
• Discuss potential obstacles to successful implementation of balanced/performance-engineered mixture design and identify strategies to mitigate such obstacles
• Assess future needs for improvement in the area of balanced/performance-engineered mixture design
Balanced/Performance-Engineered Asphalt Mixture Design – Part I
TRB Webinar Thursday, November 1, 2018
2:00 PM to 3:30 PM ET
Louay N. Mohammad, Ph.D., P.E.Department of Civil and Environmental Engineering
LA Transportation Research CenterLouisiana State University
Asphalt Mixture Design• Volumetrics
– Voids in the Total Mix, VTM– Voids in the Mineral Aggregate, VMA– Voids Filled with Asphalt, VFA
• Densification– Stages during lab compaction process
VOLUME MASS
air
asphalt
aggregate
TotalMass
TotalVolume
aggregate
ConcernsOptimum asphalt binder
content– Quantity – NOT QUALITY– Aged Binders
» Replace virgin binder» RAP and/or RAS
VOLUME MASS
air
asphalt
aggregate
TotalMass
TotalVolume
aggregate
Background Follow-up to 2018 TRB workshop 124
– Performance Balanced/Engineered Asphalt Mixture Design: Implementation Efforts and Success
Performance balanced, or engineered, asphalt mixture design is a topic of substantial interest in the asphalt pavements community.
Many groups identify integration of mechanical and performance tests with current volumetric design practice to be an encouraging method to produce longer-lasting asphalt pavements that account for the many additives and mixture types available.
Balanced/Performance-Engineered Asphalt Mixture Design – Part I – focuses on implementation efforts of performance balanced/engineered asphalt mixture design,
including successes and areas for improvement
Balanced/Performance-Engineered Asphalt Mixture Design – Part I – November 26, 2018, 2:00-3:30 ET – Presents Case studies of successful balanced/performance-engineered mixture designs
Speakers Richard Duval
– Federal Highway Administration– Balanced Mix Design in the Western United States
Derek Nener-Plante– Maine Department of Transportation– Performance-Related Specification Efforts Using the AMPT
Performance-Engineered Mixture Design (PEMD)
The Beginning of Asphalt Performance Specifications in WFLHD
Richard B. Duval, P.E.FHWA Asphalt Program Lead
AFK30/50 BMD WORKSHOP TRANSPORTATION RESEARCH BOARD
November 1, 2018
• AMPT: Asphalt Mixture Performance Tester
• AQCs: Acceptance Quality Characteristics
• BMD: Balanced Mix Design• GTR: Recycled ground tire
rubber• HMA: Hot mix asphalt• PEMD: Performance-
Engineered Mixture Design• PRS: Performance-Related
Specifications• QA: Quality Assurance
• RAP: Reclaimed asphalt pavement
• RAS: Reclaimed asphalt shingles
• SHRP 2: Strategic Highway Research Program 2
• TFHRC: Turner-Fairbank Highway Research Center
• VFA: voids filled with asphalt• VMA: voids in mineral
aggregate• WFLHD: Western Federal Lands
Highway Division
2
Acronyms
The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear only because they are considered essential to the objective of this presentation.
An ideal PEMD test supplements volumetric mixture design by using engineering and performance tests on conditioned specimens to address multiple distresses considering mixture aging, traffic, climate and location within the pavement structure as a part of the asphalt mixture design and approval process. PEMD tests should also• better characterize the appropriate asphalt content• better characterize the effect of increased use of additives,
modifiers, reclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAS), recycled ground tire rubber (GTR), and other nontraditional materials
• better characterize mixture designs that use a variety of production techniques, as well as changes to mixture design criteria
3
Performance-Engineering Mixture Design (PEMD)
PEMD and PRS
Time
PEMD: Index/Lab Mixture
Qualification
Before Construction
During Construction
After Construction
PEMD/PRS: Field Acceptance
PEMD/PRS: Field Acceptance
In-Service
PRS is the field acceptance of qualified PEMD mixtures during/after construction.
PRS also evaluates non-mixture Acceptable Quality Characteristics that affect performance; such as smoothness.
4
Quality Continuum
QA and Performance Continuum
5
Current QA Specifications
Pay Adjustments
Incentiveor
DisincentivePay Factors
AcceptableQuality
Characteristics
Strength, Air Voids, VMA,
Density,Thickness,Smoothness
etc.
6
Performance-Related Specifications (PRS)
Pay Adjustments
Incentiveor
DisincentivePay Factors
PredictedLife
As-Designed
vs.As-
Constructed
FundamentalEngineeringProperties
Strength Modulus,CrackingProperty,Rutting
Property
AcceptableQuality
Characteristics
Air Voids,Density,
Thickness,Mixture
Properties,etc.
7
8
PRS Elevator Speech
Performance related specifications (PRS) compare design expectations to what was constructed, and pay accordingly.
PRS Definition
“QA specifications that describe the desired levels of key materials and construction quality characteristics that have been found to correlate with fundamental engineering properties that predict performance”
Transportation Research Circular Number E-C137 Glossary of Highway Quality Assurance Terms
9
Project Partnership within FHWA Federal Lands Highway & Turner Fairbank Highway Research Center
SHRP2 R07 Targeted Assistance ProgramFurthering the Use of Performance Specifications
• 1960s Federal Specifications– Broadband gradation requirements– Asphalt content by weight during mixing– Asphalt cement by certification– Methods of manufacture
11
HMA Progression of Specifications
• 1970s Federal Specifications– Gradation target values and tolerances– Asphalt content target and tolerance– Density– Limited asphalt cement testing – (primarily certification)
12
HMA Progression of Specifications
• 1980s Federal Specifications– Gradation with target value and tolerance– Asphalt content with target value and
tolerance– Density– Thickness– Asphalt cement testing – limited certification– Statistical acceptance– Pay lots and pay factors
13
HMA Progression of Specifications
• 1990s Federal Specifications– Gradation with target value and tolerance– Asphalt content with target value and
tolerance– Density– Asphalt binder testing (Performance Grades)– Smoothness measurement with pay
adjustments (Profilograph)– Contractor testing with agency verification– Statistical acceptance– Pay lots and pay factors
14
HMA Progression of Specifications
• 2000s Federal Specifications– Asphalt mixture volumetrics (VMA, Air Voids, VFA)– Asphalt content with target value and tolerance– Minimum VMA– Density– Asphalt binder testing (Performance Grades)– Smoothness measurement with pay – adjustments (Inertial Profilers)– Contractor testing with agency verification– Statistical acceptance– Pay lots and pay factors
15
HMA Progression of Specifications
• Immersion – Compression• Tensile Strength Ratio• Hamburg Wheel Track Testing• Asphalt Pavement Analyzer• TSRST• Others
16
Additional Mixture Tests
• Can we…– Optimize and improve performance?– Determine how volumetrics relate to
performance and pavement life?– Develop quality adjusted pay factors that
reflect “as-constructed” pavement life?
17
Performance Specifications
• Long term pavement performance predicted from fundamental engineering properties
• Incentives and disincentives justified through reduction or increase in pavement life
• Allow contractors to be more innovative and more competitive
18
Benefits of PRS – The Future
• Testing efficiency and simplicity– Completed/Continuous
• Standardization of test methods– Submitted to AASHTO Committee on Materials &
Pavements (COMP) 2018 - Continuous• Reliability of performance prediction models
– 1st phase Completed – Still need Transfer Functions• Performance volumetric relationships
– Ongoing – Shadow Program such as WFL• Same principles and methods between mix design and
PRS– Ongoing – Future – Production Test
19
Challenges with PRS
• Perform desktop study (past project)• Shadow projects
– Performance testing / analysis– Demonstrates how PRS could be used– Understanding PRS testing and acceptance
operations– Collect data for PRS development
20
Project Outline
• Perform desktop study– Past projects– Collect test results from construction– Mix design information– Obtain field cores of existing pavement– Advanced laboratory testing– Traffic data
• Compare predicted life vs. “as-constructed”• Compare against pay factors for completed
work
21
Past Project – Desktop Study
• East Entrance Road– First WMA project constructed in 2007– Excellent traffic data– Extensive testing
(FHWA mobile lab)
22
Past Project:Yellowstone National Park
Source : FHWA - WFLHD
Typical Data – Pay Factors
Source : FHWA - WFLHD
23
• Obtain cores from existing pavement• Advanced laboratory testing –
fundamental AMPT• In-service traffic data (vehicle counts/
traffic mix)• PMS / RIP data• Performance relationships
24
Performance Testing
• Good traffic data• Good “as-constructed” project data• Obtain cores for AMPT testing
– Dynamic Modulus– Cyclic fatigue– Stress Sweep Rutting
25
Key Information for Desktop Study
A) Skyliners Road near Bend, OR (completed 2016)
B) Lake Crescent – Highway 101 in Olympic National Park, WA (currently under construction)
26
Shadow ProjectsCurrently / Recently Constructed
Source : FHWA - WFLHD
A B
• Understanding testing and analysis• Demonstrate how project would be
accepted using PRS• Understand processes and testing for
PRS type operations• Collect data for improvement and
implementation
27
Why Shadow Projects?
• Additional sampling of current project materials– Performance testing– Use of calibrated performance models– Predicted pavement life vs. volumetric
properties– “As constructed” pavement life vs. pay
factors
28
Shadow Project Data
• Asphalt concrete mix design information– Contractor mix design– Agency verification– TFHRC confirmation and comparison
• Acceptance Quality Characteristics (AQCs)– Asphalt content– VMA– Density– Asphalt binder– Roughness (IRI Evaluation)
29
Shadow Project Data
Source for Images: FHWA - WFLHD
• Verified mix design• Laboratory Batched Mix
– 3 air void contents (4%, 7%, 10%)
• Plant Produced Loose Mix– 3 air void contents (4%, 7%, 10%)
• Field Cores– Specimens obtained from field cores
30
Shadow Project Performance (AMPT) Testing at TFHRC
• Needs to be more efficient– Manufacture and production of specimens
• Simplicity– Straightforward methods
• Standardization of methodology– Provisional standards currently with AASHTO
• Use of available equipment– AMPT
31
Testing Efficiency and Samples
• Proposed to enable field core testing• To improve the efficiency of laboratory
specimen fabrication
32
Small Specimen Testing
Source : North Carolina State University
33
Test Specimens from Field Cores
Source : North Carolina State University
Testing Efficiency and Simplicity
Small Specimen
|E*| Tests Fatigue Tests
Large Specimen
|E*| Tests
Fatigue Tests
34Source : North Carolina State University
Testing Efficiency and Simplicity
Large Specimen Small Specimen
Steel Putty Devcon 10110 Devcon 10240
Working Time 10 – 20 min. 5 min.
Functional Cure 16 hours 1 hour
Amount of Putty (per specimen) 100 g 3 g
35Source : North Carolina State University
AMPT Cyclic Fatigue Process
Preparation- Cylindrical specimen- 100 mm x 130 mm
- Small-specimen: 38 mm x 110 mm
- End plate gluing, clamp system being explored
- 2-3 days for mix
Testing- Dynamic modulus
fingerprint for specimen variability
- Pull-pull fatigue test- Strain level based on TFHRC
database- Test temperature based on
location of interest- Load until crack forms
- 1-2 days for mix
Analysis- AMPT automatically captures
data for analysis- Calculate damage via FlexMAT or FlexPAVE
- Assign mixture rankings or use FlexPAVE
- 1-2 hours for mix
About one week per mixture…worth it when considering the cost of premature failure?
36
PRS Software
37
™
™ ™
™
Asphalt PRS Framework
Sampling of Mixtures/Data from
PavingProject
PerformanceTests in AMPT
FlexMATTM
Excel-Based Data Analysis
FlexPAVETM
Pavement Performance
Analysis
Prediction of Life
Construction
Application of Pay
Factors inPASSFlex™
Incentives/Disincentives
Performance Monitoring & Feedback
38
PEMD
• Predicted Pavement Performance vs. Volumetrics
• Determine as-constructed pavement life compared against as-design
• Pavement life vs. PWL pay factors• Superpave Volumetrics relation to
performance testing – PVR Relationship• Development of draft performance
specification
39
Deliverables
• Further the advancement and deployment of PRS for asphalt pavements
• Viable option for construction• Construction industry has confidence in
processes used for acceptance
40
Outcomes
AMPT Testing Standards (AASHTO)
• Specimen Preparation– R 83 (2017) Preparation of Cylindrical Performance
Test Specimens Using the Superpave Gyratory Compactor (SGC) Dynamic Modulus & Flow Number
• Dynamic Modulus– R 84 (2017) Developing Dynamic Master Curves for
Asphalt Mixtures Using the AMPT– T 378 (2017) Test for Determining the Dynamic
Modulus and Flow Number for Asphalt Mixtures Using the AMPT
41
AMPT Testing Standards in AASHTO COMP 2018
• Cyclic Fatigue (cracking)– TP 107 (2014) Determining the Damage
Characteristic Curve of Asphalt Mixtures from Direct Tension Cyclic Fatigue
• Stress Sweep Rutting– TP xx (2019) Test for Stress Sweep Rutting
(SSR) Test Using the AMPT
42
AMPT Testing Standards in AASHTO COMP 2018
• Small Scale Specimens– TP xx (2019) Preparation of Small Cylindrical
Performance Test Specimens Using the SGC and Field Cores
– TP xx (2019) Test for Determining the Dynamic Modulus for Asphalt Mixtures Using Small Specimens in the AMPT
– TP xx (2019) Test for Determining the Damage Characteristic Curve and Failure Criterion Using Small Specimens in the AMPT Cyclic Fatigue Test
43
• AASHTO T 378 |E*| – Complete!• AASHTO TP 107 – Ruggedness and
precision and bias underway• Small-specimen cyclic fatigue –
Ruggedness and precision and bias underway
Ruggedness, Precision, and Bias
44
• AL, CO, CT, FL, GA, IL, KS, KY, MO, ME, NC, NE, NH, NJ, NY, Ontario, OR, PA, PR, TN, UT, VA, WI, WV, WY, FHWA
• Baseline status of states AMPT– What is needed to get your AMPT running?
• Small Specimen Equipment• Getting involved
45
AMPT TPF-5(178) Pooled Fund
• Shadow Guidelines and Technical Support
• Performance Testing Procedures Training
• Software and Analysis Training– Understanding of PRS and how they
measure performance
• SEEKING SHADOW PROJECTS
What Will the State Highway Agency Get Out of This?
46
• State DOT determines project(s)• Develop sampling plan with support from
FHWA research contract– 10 plant-produced samples– Proficiency sample – Mix design replication sample
• Training before testing begins • Volumetric testing as normally done • AMPT/Concrete testing whenever DOT has
time
47
How Will This All Work?
• Introduction– Benefits of using PRS– Available assistance
• Overview of PRS for Asphalt– Supporting software– Concise description of the major steps
• Project description• Performance volumetric relationships and life differences• PRS pay tables• Acceptance data and payment
– PRS compared with agency practice• Lessons Learned
48
All Shadow Project Report Outline
49
Types and Uses of Construction Specifications
See our animated video at: https://www.youtube.com/watch?v=-FfOUfIbfF4&feature=youtu.be
• Contact information– Richard Duval - HQ– 202.515.1030– [email protected]
– Megan Chatfield -WFLHD– 360.619.7586– [email protected]
THANK YOU
50
PERFORMANCE-RELATED SPECIFICATION EFFORTS USING THE AMPT AFK30/50 BMD WORKSHOP - NOVEMBER 1, 2018
Derek Nener-Plante, M.S., P.E. - Asphalt Pavement EngineerMaineDOT
1
Integrity – Competence - Service
Acknowledgements2
Thanks to the following for their assistance:
Dr. Kim & NC State Students / Staff
FHWA MaineDOT lab staff
Talking Points3
Purpose: To give the motivation, methodology, early results, and lessons learned from Maine’s work with the Asphalt Mixture Performance Tetser
How? Maine’s overall plan for AMPT Proficiency Test Results Performance-Related Specification (PRS) Shadow
Project Performance-Engineered Mix Design (PEMD)
Background - MaineDOT4
Responsible for over 8,400 centerline miles of the 24,000 total miles in Maine
Average capital program of $269 million per year
Superpave mix design – full QA system based upon on volumetrics
Motivation for Change5
Background – HMA Process6
HMA acceptance program based upon PWL Volumetric requirements (Voids, VMA, VFB, AC)
Most mix designs blend different combinations of aggregatesCrushed ledge product (granite, sandstone, limestone, etc.)Crushed gravel productNatural sandsRAP (10% - 20%)
Using un-calibrated PavementME for design
Maine’s AMPT Objectives7
To provide data to predict pavement performance in the State of Maine, for potential use in the following applications: Pavement design (PavementME,
FlexPave, etc.) Performance-Related Specification
(PRS) development Performance-Engineered Mixture
Design (PEMD)
Asphalt Mixture Performance Tester Series
Dynamic Modulus, Cyclic Fatigue, and Stress-Sweep Rutting
AMPT Performance Test Methods
Dynamic Modulus Axial compression dynamic modulus test (AASHTO T
378) Dynamic modulus mastercurve and time-temperature
shift function
Cracking Resistance AMPT cyclic fatigue test (AASHTO TP 107) C vs. S (damage characteristic curve) Energy-based failure criterion Sapp cracking index parameter
Rutting Resistance Stress Sweep Rutting (SSR) test (spec under review by
AASHTO Committee on Materials & Pavements) Reduced load time and stress shift factors Shift model coefficients Permanent strain index parameter
110 mm
38 mm
100 mm
E* and Fatigue Test Specimen
178 mm
150 mm
100 mm
150 mm
Rutting Test Specimen
4 gyratory specimens needed
2 gyratory specimens needed
AMPT 38 mm Specimens
AMPT 38 mm Specimens
How?13
Setting up “calibration” projects all over the state (4-5 per year) Acquire samples of all materials in all lifts – some to be
tested and some to be retained indefinitely Test all HMA lifts in the AMPT series DM, CF, & SSR @ 5.0% air voids DM @ 7.0% air voids
Will monitor performance for years Will also build a library of different mixes across the
state Target other projects for PRS or PEMD testing –
same mix design at different volumetrics
Proficiency Tests
First step = ensure that MaineDOT labs can perform the testing
One large sample of plant produced mix was obtained from one truckMaineDOT fabricated specimens and shipped to
NCSU The same mixture were tested at MaineDOT and at
NCSU The test results were compared
Proficiency Test Results
Dynamic Modulus Tests
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E-05 1.0E-03 1.0E-01 1.0E+01 1.0E+03 1.0E+05
|E'|
(kPa
)
Reduced Frequency (Hz)
MaineDOT_1MaineDOT_2MaineDOT_3Fit_MaineDOTNCSU_1NCSU_2NCSU_3Fit_NCSU
Proficiency Test Results
Cyclic Fatigue Tests - Damage Characteristic Curve
0.0
0.2
0.4
0.6
0.8
1.0
0 50,000 100,000 150,000 200,000 250,000
C
S
MaineDOT_1MaineDOT_2MaineDOT_3Fit_MaineDOTNCSU_1NCSU_2NCSU_3NCSU_4Fit_NCSU
PRS Shadow Project
Objective: Use AMPT predictive models to show the impact of volumetric changes
10 samples were acquired in the field from the same mix design on the same project
Volumetric acceptance tests were performed on each
Performance tests were conducted on 4 of the 10 samples at MaineDOT
3 samples were shipped to NCSU.
Sample Volumetric Properties
Sample ID
Air Voids VMA Gmb Gmm%
BinderIn-place Density
Test AV
Status
Maine DOT
352 4.7 15.5 2.426 2.546 5.3 96.5 7.5 Done355 4.4 15.9 2.412 2.524 5.2 94.6 2.5 Done360 3.9 16.8 2.404 2.502 5.9 92.5 2.5 Done361 4.7 17.3 2.391 2.509 5.9 92.9 7.5 Done
NCSU353 4.5 16.4 2.406 2.519 5.5 96.0 4 On-going358 4.6 16.4 2.402 2.518 5.3 95.4 4.6 On-going362 4.4 17 2.396 2.507 5.8 94.3 5.7 Done
Sample Volumetric Properties
50
60
70
80
90
12 14 16 18 20 22
In-p
lace
VFA
In-place VMA
QA Samples @ AV Limits
As Constructed
MaineDOT Testing
NCSU Verification
Testing Results
Dynamic Modulus
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E-04 1.0E-02 1.0E+00 1.0E+02 1.0E+04
|E'|
(kPa
)
Reduced Frequency (Hz)
Specimen 1Specimen 2Specimen 3Fit
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E-04 1.0E-02 1.0E+00 1.0E+02 1.0E+04
|E'|
(kPa
)
Reduced Frequency (Hz)
Specimen 1Specimen 2Specimen 3Fit
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E-04 1.0E-02 1.0E+00 1.0E+02 1.0E+04
|E'|
(kPa
)
Reduced Frequency (Hz)
Specimen 1Specimen 2Specimen 3Fit
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E-04 1.0E-02 1.0E+00 1.0E+02 1.0E+04
|E'|
(kPa
)
Reduced Frequency (Hz)
Specimen 1Specimen 2Specimen 3Fit
159352
159355
159360
159361
Testing Results
Cyclic Fatigue Tests
0.0
0.2
0.4
0.6
0.8
1.0
0 50,000 100,000 150,000 200,000
C
S
Sample 1
Sample 2
Sample 3
Fit
0.0
0.2
0.4
0.6
0.8
1.0
0 100,000 200,000 300,000 400,000
C
S
Sample 1
Sample 2
Sample 3
Fit
0.0
0.2
0.4
0.6
0.8
1.0
0 100,000 200,000 300,000 400,000
C
S
Sample 1
Sample 2
Sample 3
Fit
0.0
0.2
0.4
0.6
0.8
1.0
0 50,000 100,000 150,000 200,000
C
S
Sample 1
Sample 2
Sample 3
Fit
159352
159355
159360
159361
Pavement Performance Prediction
Base8 in.
Asphalt4 in.
Subgrade
FlexPAVETM 1.0
Fatigue Damage Prediction
0
2
4
6
8
10
12
14
0 5000000 10000000 15000000
% D
amag
e Ar
ea
ESALs
159352_AV 7.5%159355_AV 2.5%159360_AV 2.5%159361_AV 7.5%159362_AV 5.7%
Rutting Depth Prediction
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 100 200 300 400
Rut D
epth
(mm
)(A
C O
nly)
Time (month)
159352_AV 7.5%159355_AV 2.5%159360_AV 2.5%159361_AV 7.5%159362_AV 5.7%
Performance-Volumetric Relationship (PVR)
The PVR was calibrated using the performance test results generated by MaineDOT.
PVR was used to predict performance for mixes with different volumetric properties that were tested at NCSU for verification.
Verification of Cracking PVR
Fatigue damage in 4-inch asphalt pavement
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12 14
Pred
icte
d %
Dam
age
Area
FlexPAVE % Damage Area
Calibration Sections
Verification Section
Verification of Rutting PVR
Rut depth of the AC layer in the 4 inch pavement
0.0
0.5
1.0
1.5
2.0
0 0.5 1 1.5 2
Pred
icte
d Ru
t Dep
th (m
m)
FlexPAVE Rut Depth (mm)
Calibration Sections
Verification Sections
Fatigue Index Parameter
Sapp
Fatigue resistance index Considers both modulus and ductility
Traffic Level (million ESALs)
Sapp Tier Designation
<= 3 Sapp <= 8 Light L>3 and <=10 8< Sapp <=18 Standard S
>10 and <= 30 18< Sapp <=25 Heavy H>30 25< Sapp <=30 Very Heavy V
>30 and slow traffic Sapp >30Extremely
HeavyE
% Damage from FlexPAVETM vs. Sapp
R² = 0.9836
0
2
4
6
8
10
12
14
0 10 20 30 40
% D
amag
e Ar
ea
Sapp
Sample ID Test AV Sapp
159352 7.5 16.8159355 2.5 29.3159360 2.5 31.3159361 7.5 18.1159362 5.7 26.5
PEMD Concept30
Volumetric Design
AMPT Testing @
4.0% voids
Check against criteria
Adjust asphalt content
AMPT Testing at
new target
Check against criteria
Performance-Engineered Mix Design
% AC
Cra
ckin
g R
esis
tanc
e Rutting R
esistanceVolumetric optimum
Candidate Performance Optimum
Final optimum
Minimum Required
Minimum Required
Performance-Engineered Mix Design
% AC
Cra
ckin
g R
esis
tanc
e Rutting R
esistanceVolumetric optimum
Candidate Performance Optimum
?Predictive Equations
or Agency’s Experience
Methodology33
12.5 mm NMAS – 75 gyration – 20% RAP PG 64-28 binder (PPA modified <1%) Four different asphalt contents
Target - 0.5% (5.1%) Target (5.6%) Target + 0.5% (6.1%) Target + 1.0% (6.6%)
Rutting Performance34
Rutting Performance35
DR Failure Criterion and Modulus36
Measure of Toughness
Measure of Stiffness
Sapp as a Fatigue Cracking Index37
0
5
10
15
20
25
5.10% 5.60%(Target)
6.10% 6.60%
Sapp
Fatigue Cracking Performance of Maine Mix Compared to Other Mixtures
38
Rutting Performance of Maine Mix Compared to Other Mixtures
39
PEMD Lessons Learned - Overall40
Current mix design aim (5.6% AC) appears to optimize performance (fatigue cracking / rutting)
Data acquired follows logical mix design trends
Testing time for the PEMD approach is rather long, although it can be reduced
Steep learning curve with AMPT testing –although it does enhance fundamental understanding of mixes
AMPT Lessons Learned - Testing41
Cyclic fatigue – Use bearing with top spacer plate for higher success rate. I suspect some of our failed test are due to stresses during bolt-up due to slightly non-parallel ends.
Cyclic fatigue – Allow 1.5hrs once bolted in AMPT to fully climatize prior to running the dynamic modulus fingerprint test (helps prevent unacceptable errors in the Dynamic Modulus Ratio between the dynamic modulus and cyclic fatigue data).
Cyclic fatigue – Be conservative when selecting the on-specimen strain rate, we had to decrease the on-specimen strain levels in order to stop end failures (failures outside the gauge points).
Dynamic Modulus – It isn’t surprising if some of the quality indicators fall slightly outside of the acceptable range, especially at high temp.
Tuning – Take the time at the beginning to work with tuning to get appropriate PID values, defaults were significantly off.
Coring – If your small specimens are coming out slightly ribbed, try decreasing the water pressure feeding the drill.
Equipment – Suggestion to have 6 pairs of cyclic fatigue end plates and 72 Gauge Points (LVDT studs to be able to prepare specimens while climatizing and testing others to maximize efficiency).
AMPT Lessons Learned42
Its all in the details…Selection of air
void contentUse of CoreLok
for air void determination
Sealing of samples after receipt
Proper storage
Observations to Date
The proficiency test results showed MaineDOT was able to perform the AMPT tests and generate high-quality data.
The test results from the shadow mixes showed the test methods are able to predict the different pavement performance due to changes of AQC parameters.
The performance-volumetric relationship was used to predict the pavement performance based on AQC data.
The preliminary mix design and test confirmed the capacity of the mechanistic models and verified the original volumetric design of the mix.
Any Questions?
Derek Nener-Plante, M.S., PEAsphalt Pavement Engineer
Thank you for the opportunity.44
Today’s Speakers
• Louay Mohammad, Louisiana State University, [email protected]
• Richard Duval, Federal Highway Administration, [email protected]
• Derek Nener-Plante, Maine Department of Transportation, [email protected]
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Receiving PDH credits
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