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– Richard.duval@dot.gov

– Megan Chatfield -WFLHD– 360.619.7586– Megan.Chatfield@dot.gov

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

Derek.Nener-Plante@maine.gov207-215-0849

Thank you for the opportunity.44

Today’s Speakers

• Louay Mohammad, Louisiana State University, louay.mohammad@la.gov

• Richard Duval, Federal Highway Administration, Richard.Duval@dot.gov

• Derek Nener-Plante, Maine Department of Transportation, derek.nener-plante@maine.gov

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