J.4 Tech Assistance Report Sample.pdf

Executive Summary of MATC Site Visit – Western Federal Lands 1

Executive Summary FHWA MATC Site Visit with Western Federal Lands

February 26, 2024

About the Program:

The Federal Highway Administration (FHWA) Mobile Asphalt Technology Center (MATC) is a traveling asphalt mixture laboratory facility and is supported by its stationary support laboratory, the Asphalt Binder and Mixture Laboratory – Implementation and Delivery (ABML- ID), located at the FHWA Turner Fairbank Highway Research Center in McLean, Virginia, to provide technical excellence to the asphalt pavement community. The MATC is equipped with traditional and state-of-the-art testing equipment that is ready, or nearly ready, for widespread use in the highway industry. The MATC is a vital mechanism for technology implementation and allows FHWA to advance policy and technical support through identifying regional and national trends in asphalt materials and pavement construction.

Project Details:

In March 2023 the Western Federal Lands Highway Division Office of FHWA (WFL) began discussions with the MATC Team regarding a possible onsite visit to an active paving project in their jurisdiction. A few weeks later a Kickoff Meeting was held to provide an overview of the MATC Program and the support available to their office.

WFL welcomed the support and discussions began regarding details of the upcoming site visit. The primary reason for the visit was to assist with testing and evaluating a typical WFL surface mixture for Balanced Mix Design (BMD) implementation. Along with the mixture evaluation, laboratory and field-testing technologies were also demonstrated both at the MATC lab and on the live paving project selected by WFL. The MATC arrived at the Old Faithful Headquarters in Yellowstone National Park on June 29th and remained onsite until July 28th. The figure below shows the overall project timeline for the MATC’s assistance to Western Federal Lands.

March 20:

Kickoff

Meeting with WFL to introduce

MATC

Program

June 22:

MATC

submitted Draft Testing Plan to WFL for approval

June 29:

MATC

arrived at Old Faithful

HQ's in Yellowstone

Nat. Park

July 7:

Open House Event held at

MATC for WFL and

Local Industry

July 28:

MATC

departed completing the onsite sampling and testing

Sept 25:

MATC

completed Test Plan and began analysis & reporting

Feb 26:

Draft

Technical Assistance

Report submitted to

WFL

Executive Summary of MATC Site Visit – Western Federal Lands 2

Testing Performed:

For the mixture volumetrics & performance testing portion of the test plan, the MATC evaluated a typical asphalt pavement surface mixture, as selected by WFL, with performance testing to provide information for potential Balanced Mixture Design (BMD) implementation. Index values from the selected tests were determined for the materials currently in use and provided to WFL with a baseline of results to work from. The project mixture was a WFL 401 surface mix, with a Nominal Maximum Aggregate Size (NMAS) of 3/4" (19.0mm) and a PG58-34 asphalt binder.

Secondly, for the asphalt binder testing, samples of the PG58-34 binder were obtained for purposes of determining both its continuous grade and premature cracking potential, as well as performing testing and analysis to determine its elemental makeup and to identify the presence of any additives and/or contaminants.

And finally, while onsite, the MATC Team was able to demonstrate the Paver-Mounted Thermal Profiler (PMTP) system as a high precision real-time thermal profiler to detect pavement mat defects before compaction, the Dielectric Profiling System (DPS) as a non-destructive tool to continuously assess asphalt pavement compaction quality through measuring the pavement’s dielectric constant, the use of Pulse Induction Technology as a non-destructive test to measure pavement layer thickness, and the Laser Texture Scanner (LTS) to measure surface macrotexture of the asphalt mat.

Technical Findings:

The key technical findings from the MATC test plan are presented below. Detailed information on the test results is available in the full technical assistance report.

Mixture Volumetrics & Performance Testing Asphalt content, gradation, and volumetric property test results indicated that the six (6) Production Mix samples of the WFL 401 3/4" mixture were representative of the producer’s JMF and relatively consistent.

Sample S5 did show differences which were likely due to a reduction in fines as evident by a lower %Passing the #200 sieve than the rest of the samples.

IDEAL-CT test results indicated that there was good agreement between lab-produced testing at mix design and field-produced samples in production. The IDEAL-CT samples did show higher than typical within-specimen variability, with the majority of samples having COV’s greater than 20%, which has been observed by others. This high variability could lead to confidence issues during production QC/QA testing.

IDEAL-CT testing of samples subjected to long-term aging showed good agreement in the CTindex reduction between lab-produced and field-produced specimens.

IDEAL-RT test results also indicated that there was good agreement between lab-produced testing at mix design and field-produced samples in production. Also, test results were typical of a mixture utilizing a PG58 binder based on the criterion that is currently being suggested by the test developers.

Hamburg Wheel Tracking Test results for both the Mix Design and Production Mix indicated good rutting resistance with final rut depths (for all but one test replicate) of less than 5.0mm, after 20,000 cycles. Test results for Production Mix sample S5 indicated some level of stripping, and the sample’s low dust content and stripping could indicate the potential absence of lime in the mixture.

Asphalt Binder Testing

Performance Grading of the PG58-34 asphalt binder showed a Continuous Performance Grade of PG61.7-35.5 and a MSCR grading of PG58V-34.

The ∆Tc values of both asphalt binders were above the -5.0°C minimum threshold for both 20-hr and 40-hr aging, indicating the binders are resistant to excessive binder stiffening after extended mixture aging.

After 20-hr PAV aging the asphalt binder also had ∆Tc and ∆Tf values which would meet the requirements of the proposed specification framework as reported in NCHRP 09-60.

Executive Summary of MATC Site Visit – Western Federal Lands 3

XRF testing of the PG58-34 asphalt binder indicated that it is highly unlikely that there was any REOB or PPA in the sample, while the FTIR testing did show peaks for both Polystyrene and Butadiene – thus, indicating the presence of an SBS modifier.

Field Technology Demonstrations

PMTP demonstration showed the operational challenges faced by the crew when either longer haul distances or traffic congestion affects the consistent delivery of mix and the effect it has on minimum mat temperatures and overall consistency.

The MATC Team showed that the DPS system can be used on any moisture-free pavement surface to help paving contractors and agencies to assess pavement compaction uniformity and field densities, especially at joints. It can also be used to identify critical factors that influence in achieving higher density in the field.

The Pulse Induction Technology was shown to accurately measure mat thicknesses and is a “ready to use” non-destructive way to verify placement rate.

Laser Texture Scanner measurements to determine the mean profile depth (MPD) of the US191 surface mixture correlated well with typical ranges for that mix type, as published in the 2022 AASHTO Guide for Pavement Friction.

Parting Considerations

Balanced Mix Design (BMD) has the potential to capture aspects of asphalt mixture performance in respect to distresses not currently captured by volumetric design processes. The implementation of BMD may be able to provide an optimization of mixture properties to meet performance needs.

The PMTP technology should be considered for adoption by paving contractors for use in QC as a way to ensure consistent, uniform mat temperatures behind the paver, and bring awareness to the impact of extended paver stops on achieving mat density.

i

1200 New Jersey Avenue, SE Washington, DC 20590

202-981-2875 FHWA-MATC@dot.gov

FHWA Mobile Asphalt Technology Center (MATC) Western Federal Lands

February 26, 2024

FHWA MATC Project # WFL 23126

Federal Highway Administration

Office of Preconstruction, Construction, and Pavements ii

Table of Contents List of Acronyms and Abbreviations .................................................................................................................... iv

List of Tables ...................................................................................................................................................... vi

List of Figures .................................................................................................................................................... vii

About the Program

Project Details

Sampling & Fabrication

Tests and Analyses Performed

Summary of Results

Mixture Testing & Analysis

Asphalt Binder Testing & Analysis

Field Testing Demonstrations & Analysis

Parting Considerations

Appendix A — Mixture Volumetrics & Performance Testing

Mixture Properties & Volumetrics

Asphalt Content & Gradation:

Mixture Specific Gravities & Volumetric Properties:

Mixture Performance Tests

IDEAL Cracking Test

IDEAL Rutting Test

Hamburg Wheel Tracking Test

Appendix B — Asphalt Binder Testing

Performance Grading & Binder Aging Analysis

X-ray Fluorescence Spectroscopy (XRF) Testing

Fourier Transform Infrared Spectroscopy (FTIR) Testing

Appendix C — Field Testing Demonstrations iii

Thermal Profile Testing

Mat Density Testing

Mat Thickness Testing

Surface Macrotexture Testing

References:

iv

List of Acronyms and Abbreviations oC Degrees Centigrade

% Percent

3D Three Dimensional

AASHTO American Association of State Highway and Transportation Officials

ABCD Asphalt Binder Cracking Device

ABML FHWA Asphalt Binder and Materials Laboratory

AC Asphalt Content

ASTM American Society for Testing and Materials

BBR Bending Beam Rheometer

BMD Balanced Mix Design

COV Coefficient of Variation

CTIndex Cracking Tolerance Index

D/B Dust-to-Binder Ratio

DGA Dense-Graded Asphalt

DOT Department of Transportation

DPS Dielectric Profiling System

DMI Distance Measuring Instrument

∆Tc Asphalt Binder Parameter for Cracking

∆Tf Asphalt Binder Parameter for Fatigue Cracking

FHWA Federal Highway Administration

Gmb Bulk Specific Gravity of the Mixture

Gmm Theoretical Maximum Specific Gravity of Mixture

GPR Ground Penetrating Radar

GPS Global Positioning System

HMA Hot Mix Asphalt

HWTT Hamburg Wheel Tracking Test

IDEAL-CT Indirect Tension Asphalt Cracking Test

IDEAL-RT Indirect Tension Asphalt Rutting Test

JMF Job Mix Formula

LDL Lower Design Limit

LPL Lower Production Limit v

LTS Laser Texture Scanner

MATC Mobile Asphalt Technology Center mm Millimeters

MP Milepost

MPD Mean Profile Depth

MSCR Multiple Stress Creep Recovery

N/A Not Applicable

NCHRP National Cooperative Highway Research Program

NMAS Nominal Maximum Aggregate Size

PAV Pressure Aging Vessel

Pb Percent Binder (Asphalt Content)

PG Performance Grade

PMTP Paver-Mounted Thermal Profiler

QA Quality Acceptance

RAP Recycled Asphalt Pavement

RTFO Rolling Thin-Film Oven

RTIndex Rutting Tolerance Index

SBS Styrene-Butadiene-Styrene modifier

SHRP Strategic Highway Research Program

UDL Upper Design Limit

UPL Upper Production Limit

US191 U.S. Highway 191

VFA Voids Filled with Asphalt

VMA Voids in Mineral Aggregate

VTM Voids in Total Mix

WFL FHWA’s Western Federal Lands Highway Division vi

List of Tables Table 1: Mixture Samples Obtained for Testing

Table 2: Mixture Volumetric & Performance Testing Requirements (per sample)

Table 3: Asphalt Binder Testing Requirements

Table 4: Coring Requirements for Field Demonstrations

Table 5: MATC Test Plan for Western Federal Lands Site Visit

Table 6: Mix Design Limits, JMF, and Production Limits for the WFL 401Mixture

Table 7: Gradation Results for the WFL 401 Production Mix Samples

Table 8: Average IDEAL-CT Testing Results

Table 9: Average IDEAL-RT Testing Results

Table 10: Asphalt Binder Performance Grading Summary

Table 11: ∆Tc Summary

Table 12: ∆Tf Summary

Table 13: Summary of XRF Spectrometer Analysis of the PG58-34 Binder

Table 14: Thermal Profile Summary for the US191 Test Section vii

List of Figures Figure 1: Key Project Details for MATC Site Visit to Western Federal Lands

Figure 2: Volumetric & Performance Testing Evaluation of the WFL 401 Mixture

Figure 3: Asphalt Content by Ignition Results for the WFL 401 Production Mix Samples

Figure 4: Gradation Results for the WFL 401 Production Mix Samples

Figure 5: Gmm Results for the WFL 401 Production Mix Samples

Figure 6: Gmb Results for the WFL 401 Production Mix Samples

Figure 7: %VTM Results for the WFL 401 Production Mix Samples

Figure 8: %VMA Results for the WFL 401 Production Mix Samples

Figure 9: %VFA Results for the WFL 401 Production Mix Samples

Figure 10: IDEAL-CT Test Setup

Figure 11: IDEAL-CT Test Results

Figure 12: IDEAL-CT (Gf vs l75/m75) Interaction Diagram

Figure 13: IDEAL-RT Test Setup

Figure 14: IDEAL-RT Test Results

Figure 15: Hamburg Wheel Tracking Tester

Figure 16: Hamburg Wheel Tracking Test Results

Figure 17: Post-Test Images of Production Mix Sample S1 Tested at 45°C

Figure 18: Post-Test Images of Production Mix Sample S5 Tested at 50°C

Figure 19: HWTT Rutting Plots for Production Mix Sample S5 Tested at 50°C

Figure 20: Proposed Specification Framework for ∆Tc and ∆Tf from NCHRP 09-60

Figure 21: MATC's X-ray Fluorescence Spectroscopy Testing Equipment

Figure 22: Fourier-Transform Infrared Spectroscopy Equipment

Figure 23: FTIR Spectra of the PG58-34 Asphalt Binder

Figure 24: PMTP Device Mounted on Mast Above Paver Screed

Figure 25: Typical Thermal Infrared Image of Mat Surface Behind Paver

Figure 26: Thermal Infrared Image vs Paver Stops on US191 Test Section

Figure 27: Distribution of Placement Temperatures for the US191 Test Section

Figure 28: DPS Device Being Used in the Field

Figure 29: Typical Dielectric Map Generated by DPS Device

Figure 30: DPS Dielectric Maps of the US191 Test Section

Figure 31: Distribution of Dielectric Readings for the US191 Test Section https://usdot.sharepoint.com/teams/MPTCTeams-MATC/Shared%20Documents/Site%20Visits/WFL%2023126/MATC%20Technical%20Assistance%20Report_WFL_Final.docx#_Toc158354215 viii

Figure 32: Placing the PIT Target and Performing the Scan

Figure 33: Pulse Induction Measurements vs. Cores from US191 Test Section

Figure 34: Laser Texture Scanner

Figure 35: Typical LTS Scanned Image of Gyratory Specimen

Figure 36: Typical LTS Line Scan Macrotexture Plot

Figure 37: LTS Field vs. Lab Measurements for US191’s 19.0 NMAS Test Section

Mobile Asphalt Technology Center (MATC) Site Visit to Western Federal Lands

February 26, 2024

About the Program

The mission of the Federal Highway Administration (FHWA) Mobile Asphalt Technology Center

(MATC) is to:

• Bring new and emerging asphalt materials and construction technologies to the pavement community, bridging the gap between research and implementation;

• Provide leadership and technology for the delivery of long-life pavements that meet our stakeholders’ needs and are safe, sustainable, and effectively maintained;

• Assist in advancement of new and underutilized technologies and innovations into common practice; and

• Raise awareness and assist FHWA field offices, State Departments of Transportation, and their private sector, local agency, and academic partners in the area of pavements and materials.

Project Details

In March 2023 the Western Federal Lands Highway Division Office of FHWA (WFL) began discussions with the MATC Team regarding a possible onsite visit to an active paving project in their jurisdiction. A few weeks later a Kickoff Meeting was held to provide an overview of the MATC

Program and the support available to their office. WFL welcomed the support and discussions began regarding details of the upcoming site visit. The primary reason for the visit was to assist with testing and evaluating a typical WFL surface mixture for Balanced Mix Design (BMD) implementation. Along with the mixture evaluation, laboratory and field-testing technologies were also demonstrated both at the MATC lab and on the live paving project selected by WFL. The

MATC arrived at the Old Faithful Headquarters in Yellowstone National Park on June 29th and remained onsite until July 28th. Figure 1 shows the location of the MATC in Yellowstone National

Park, as well as the location and detail of the project that was visited while the team was onsite.

The U.S. Government does not endorse products or manufacturers. Equipment and test names appear in this report because they were used during the Western Federal Lands site visit.

Figure 1: Key Project Details for MATC Site Visit to Western Federal Lands

The primary goals of the testing plan for the site visit were as follows:

• Mixture Volumetrics & Performance Testing: Evaluate typical asphalt pavement surface mixture, as selected by WFL, with performance testing to provide information for potential

Balanced Mixture Design (BMD) implementation. Index values from the selected tests will be determined for the materials currently in use and provided to WFL with a baseline of results to work from. The project mixture is a WFL 401 surface mix, with a Nominal

Maximum Aggregate Size (NMAS) of 3/4" (19.0mm) and a PG58-34 asphalt binder. The overall testing plan for the WFL 401 mixture is displayed graphically in Figure 2 below and is discussed in more detail under the Sampling & Fabrication section.

• Asphalt Binder Testing: Samples of the WFL 401 mixture’s asphalt binder were used for purposes of determining both its continuous grade and premature cracking potential, as well as performing testing and analysis to determine both its elemental makeup and look for the presence of any additives and/or contaminants. While onsite the MATC Team performed

X-Ray Fluorescence Spectroscopy (XRF) analysis to determine elemental composition and the presence of modifiers in the project binder samples. The remaining portions of the asphalt binder samples were sent to FHWA’s Asphalt Binder and Materials Laboratory

(ABML) in McLean, VA where the following tests and analyses were also performed:

• Performance grading of the binder in accordance with AASHTO M 320 & M 332.

• Aging characteristics of the binder using 20-hour Pressure Aging Vessel (PAV) and

40-hour extended aging in accordance with AASHTO R 28.

• Advanced parameter analysis for asphalt binder durability including ∆Tc & ∆Tf.

• Fourier Transform Infrared (FTIR) spectroscopy to conduct a chemical analysis.

• Field Testing Demonstrations: On the live paving project, as identified by WFL, the MATC

Team demonstrated the Paver-Mounted Thermal Profiler (PMTP) system as a high precision

WFL Project Mixture

Production Testing

Plant Mix Sample 1

AC, Gradation, & Volumetrics

IDEAL-CT

IDEAL-RT

HWTT

Plant Mix Sample 2

AC, Gradation, & Volumetrics

IDEAL-CT

IDEAL-RT

IDEAL-CT

(w/Aging)

Plant Mix Sample 3

AC, Gradation, & Volumetrics

IDEAL-CT

IDEAL-RT

HWTT

Plant Mix Sample 4

AC, Gradation, & Volumetrics

IDEAL-CT

IDEAL-RT

IDEAL-CT

(w/Aging)

Plant Mix Sample 5

AC, Gradation, & Volumetrics

IDEAL-CT

IDEAL-RT

HWTT

Plant Mix Sample 6

AC, Gradation, & Volumetrics

IDEAL-CT

IDEAL-RT

IDEAL-CT

(w/Aging)

JMF

Testing

Lab Mix Samples

IDEAL-CT

IDEAL-RT

IDEAL-CT

(w/Aging)

HWTT

Figure 2: Volumetric & Performance Testing Evaluation of the WFL 401 Mixture real-time thermal profiler to detect pavement mat defects before compaction, the Dielectric

Profiling System (DPS) as a non-destructive tool to continuously assess asphalt pavement compaction quality through measuring the pavement’s dielectric constant, the use of Pulse

Induction Technology (PIT) as a non-destructive test to measure pavement layer thickness, and the Laser Texture Scanner (LTS) to measure surface macrotexture of the asphalt mat.

Sampling & Fabrication

For purposes of evaluating the WFL 401 surface mixture, a preliminary baseline performance evaluation was first performed prior to the MATC being onsite. The material components for the

“as designed” 401 asphalt mixture were obtained by WFL representatives and shipped to the

MATC for testing. For the “live” Production Mix evaluation performed while the MATC was onsite, plant-produced loose mixture samples were obtained by the MATC Team, for use in both volumetric property and performance testing. The sampling techniques used in the field followed WFL’s typical practice for obtaining large quantity samples of plant-produced mixtures. Additional material was obtained to satisfy the mass requirements for the additional fabrication and testing. For purposes of comparing the MATC volumetric test results, WFL staff and laboratories performed normal acceptance testing on the asphalt mixture during production.

For the plant-produced 401 asphalt mixture, there was one (1) sample obtained per production day, over six (6) consecutive days, for a total of six (6) plant-produced loose mix samples. These six different samples reflected production variability in actual mixture volumetrics and properties for which to compare results. From these six samples, the MATC team performed volumetric property testing as well as fabricated specimens for each of the performance tests included in this part of the test plan. Individual aggregate stockpile samples of the WFL 401 mixture were used to determine an ignition furnace correction factor for use in asphalt content testing. Table 1 below gives the details of each of the production mixture samples obtained while the MATC was onsite and their testing protocol, while Table 2 details the necessary specimens for each performance test and the associated requirements, for each of the individual plant-produced loose mixture samples obtained.

Table 1: Mixture Samples Obtained for Testing

WFL

Material Class

& Mix ID

Sample Date & Time

Sample Location & Size

MATC Sample Identification

Mixture Testing Protocol

WFL 401

19.0mm NMAS

PG58-34

07/10/23 ≈ 6:30pm

Truck at Plant ≈ 400 lbs. S1

Asphalt Content Gradation Volumetrics

IDEAL-CT

IDEAL-CT (aged)

IDEAL-RT

HWTT

07/11/23 ≈ 6:45pm

Truck at Plant ≈ 400 lbs. S2

07/12/23 ≈ 6:50pm

Truck at Plant ≈ 400 lbs. S3

07/13/23 ≈ 6:50pm

Truck at Plant ≈ 400 lbs. S4

07/17/23 ≈ 6:55pm

Truck at Plant ≈ 400 lbs. S5

07/18/23 ≈ 6:48pm

Truck at Plant ≈ 400 lbs. S6

Table 2: Mixture Volumetric & Performance Testing Requirements (per sample)

Requirement Asphalt Content, Gradation, and

Volumetrics

Cracking Performance Rutting Performance

IDEAL-CT IDEAL-CT

(w/Aging) IDEAL-RT HWTT

Test Method

AASHTO T30,

T166, T209, T308, T312

ASTM D8225 ASTM D8225 N/A AASHTO T324

Number of Specimens 3+ 5+ 5+ 5+ 4+

Specimen Geometry

150mm diam.

115mm height

150mm diam.

62mm height

150mm diam.

62mm height

150mm diam.

62mm height

150mm diam.

62mm height

Specimen Air Voids Ndesign 7.0 ± 0.5% 7.0 ± 0.5% 7.0 ± 0.5% 7.0 ± 0.5%

Test Temperature (°C) - 25 25 50 45 and 50

Mass Required* 60lbs+ 60lbs+ 60lbs+ 60lbs+ 30lbs+

*Note: Total mass required for each production sample was approximately 270lbs.+ (Five full 5-gallon metal buckets)

For the purposes of evaluating the WFL 401 mixture’s asphalt binder, the MATC Team relied on both WFL and the producer to assist in obtaining 2 one-gallon samples and 1 one-quart sample of the project binder to complete the testing protocol shown in Table 3 below.

Table 3: Asphalt Binder Testing Requirements

Sample Size (per binder)

Performance Grading

(AASHTO M320 & M332)

20-hr

PAV

Aging

40-hr Extended

Aging

X-ray Fluorescence Spectroscopy

(XRF)

Fourier Transform Infrared

Spectroscopy

(FTIR)

2 Gallons

1 Quart

3 replicates 3 replicates 3 replicates 3 replicates 3 replicates

Field Testing demonstrations were performed on the live paving project, as identified by WFL. For the purposes of completing the MATC’s surface macrotexture evaluation using the Laser Texture

Scanner (LTS), six (6) 6-inch roadway cores were obtained for laboratory comparison scans. These same six cores were also used to verify the mat thickness measurements taken using Pulse Induction

Technology. Along with coring, the surface macrotexture evaluation also required additional loose mixture samples to be taken during that same day of production. These loose mix samples were used to fabricate laboratory compacted specimens that were also tested with the LTS to compare against in-place field measurements. This exercise allowed for the comparison of macrotexture measurements of both the lab-compacted gyratory samples and the macrotexture measurements of the in-place mat immediately after placement and compaction in the field. Table 4 below details the roadway cores that were needed to complete the demonstrations of the various field-testing technologies.

Table 4: Coring Requirements for Field Demonstrations

Thermal Profile

Mat Density

Mat Thickness

Surface Macrotexture

Total 6” Cores Paver-Mounted Thermal Profiler

(PMTP)

Dielectric Profiling System

(DPS)

Pulse Induction Technology

Laser Texture Scanner

(LTS)

0 cores 0 cores 6 cores

3 from two different shifts (PM & AM) during the same day of production and placement.

6 cores

Tests and Analyses Performed

The tests and analyses performed by the MATC comprised of three categories:

• Mixture Volumetrics & Performance Testing

• Asphalt Binder Testing

• Field Testing Demonstrations

Table 5 below shows the MATC’s test plan that was developed in coordination with WFL. The test results are summarized in the next few pages; however, the reader who is unfamiliar with a test or who wishes to review the details of a test and its results can examine the discussion of that test in either Appendix A – Mixture Volumetrics & Performance Testing, Appendix B – Asphalt Binder

Testing, or Appendix C – Field Testing Demonstrations.

Table 5: MATC Test Plan for Western Federal Lands Site Visit

JMF & Production Mixture Testing Asphalt Binder

Testing Field Testing

Demonstrations Volumetrics Performance Testing

Asphalt Content by Ignition

IDEAL-CT

(CTIndex)

Performance Grading

AASHTO M 320

AASHTO M 332

Paver-Mounted Thermal Profiler (PMTP)

Gradation

IDEAL-CT

(CTIndex) w/Aging

20-hr PAV Aging

40-hr Extended Aging

Dielectric Profiling System (DPS)

Mixture Gravities (Gmb & Gmm)

IDEAL-RT

(RTIndex)

X-Ray Fluorescence Spectroscopy (XRF)

Pulse Induction Technology (PIT)

VTM, VMA, VFA

Hamburg Wheel

Tracking Test

(HWTT)

Fourier Transform Infrared Spectroscopy

(FTIR)

Laser Texture Scanner

(LTS)

Summary of Results

Mixture Testing & Analysis

• Asphalt content, gradation, and volumetric property test results indicate that the six (6)

Production Mix samples of the WFL 401 3/4" mixture were representative of the producer’s

JMF and relatively consistent. Sample S5 did show differences which were likely due to a reduction in fines as evident by a lower %Passing the #200 sieve than the rest of the samples.

• IDEAL-CT test results indicate that there was good agreement between lab-produced testing at mix design and field-produced samples in production. The IDEAL-CT samples did show higher than typical within-specimen variability, with majority of samples having COV’s greater than 20%, which has been observed by others. This high variability could lead to confidence issues during production QC/QA testing.

• IDEAL-CT testing of samples subjected to long-term aging showed good agreement in the

CTindex reduction between lab-produced and field-produced specimens.

• IDEAL-RT test results also indicated that there was good agreement between lab-produced testing at mix design and field-produced samples in production. Also, test results were typical of a mixture utilizing a PG58 binder based on the criterion that is currently being suggested by the test developers.

• Hamburg Wheel Tracking Test results for both the Mix Design and Production Mix indicated good rutting resistance with final rut depths (for all but one test replicate) of less than 5.0mm, after 20,000 cycles. Test results for Production Mix sample S5 indicated some level of stripping, and the sample’s low dust content and stripping could indicate the potential absence of lime in the mixture.

Asphalt Binder Testing & Analysis

• Performance Grading of the PG58-34 asphalt binder showed a Continuous Performance

Grade of PG61.7-35.5 and a MSCR grading of PG58V-34.

• The ∆Tc values of both asphalt binders were above the -5.0°C minimum threshold for both

20-hr and 40-hr aging, indicating the binders are resistant to excessive binder stiffening after extended mixture aging.

• After 20-hr PAV aging the asphalt binder also had ∆Tc and ∆Tf values which would meet the requirements of the proposed specification framework as reported in NCHRP 09-60.

• XRF testing of the PG58-34 asphalt binder indicated that it is highly unlikely that there is any REOB or PPA in the sample, while the FTIR testing did show peaks for both Polystyrene and Butadiene – thus, indicating the presence of an SBS modifier.

Field Testing Demonstrations & Analysis

• PMTP demonstration showed the operational challenges faced by the crew when either longer haul distances or traffic congestion affects the consistent delivery of mix and the effect it has on minimum mat temperatures and overall consistency.

• The MATC Team showed that the DPS system can be used on any moisture-free pavement surface to help paving contractors and agencies to assess pavement compaction uniformity and field densities, especially at joints. It can also be used to identify critical factors that influence in achieving higher density in the field.

• The Pulse Induction Technology was shown to accurately measure mat thicknesses and is a

“ready to use” non-destructive way to verify placement rate.

• Laser Texture Scanner measurements to determine the mean profile depth (MPD) of the

US191 surface mixture correlated well with typical ranges for that mix type, as published in the 2022 AASHTO Guide for Pavement Friction (American Association of State

Highway and Transportation Officials (AASHTO), 2022).

Parting Considerations

• Balanced Mix Design (BMD) has the potential to capture aspects of asphalt mixture performance in respect to distresses not currently captured by volumetric design processes.

The implementation of BMD may be able to provide an optimization of mixture properties to meet performance needs.

• The PMTP technology should be considered for adoption by paving contractors for use in

QC as a way to ensure consistent, uniform mat temperatures behind the paver, and bring awareness to the impact of extended paver stops on achieving mat density.

Appendix A — Mixture Volumetrics & Performance Testing

Mixture Properties & Volumetrics

The MATC was provided the approved Job Mix Formula (JMF) for the WFL 401 surface mixture.

Utilizing the Federal Project Standard Specifications, FP-14 (Federal Highway Administration, 2014) for the construction of roads and bridges as a guideline, the MATC reviewed the specifications for both designing and producing the project mixture. Table 6 below presents a summary, which includes the design limits, the JMF, and the specified production limits. The design mixture was classified as a 3/4" (19.0mm) NMAS, comprised of three different aggregate sizes;

Crushed Coarse, Chips, and Crushed Fines, as well as 1% Lime (by weight of aggregate), which was added to wet aggregate prior to entering the dryer drum, to address any potential asphalt stripping concerns. There were no recycled material components (RAP or RAS) in the mixture, and the design asphalt binder content was 5.52% by mass of total mix.

Table 6: Mix Design Limits, JMF, and Production Limits for the WFL 401Mixture

Property Design Limits JMF Production Limits

Gradation (Percent Passing)

1” 100 100.0 100 3/4" 90 – 100 100.0 97.0 – 100 1/2" < 90 85.5 81.5 – 89.5 3/8” 70.0 65.0 – 75.0 #4 45.8 38.8 – 52.8 #8 23 – 49 31.7 26.7 – 36.7 #30 16.4 13.4 – 19.4 #50 11.3 8.3 – 14.3 #200 2 – 8 5.8 3.8 – 7.8

Volumetric Properties

Asphalt Content (%) - 5.52 5.12 – 5.92 Max. Specific Gravity (Gmm) - 2.412 Eff. Specific Gravity (Gse) - 2.618 Bulk Specific Gravity (Gmb) - 2.293

Voids in Total Mix (%) Target 4.0 4.0 Voids in Mineral Aggregate (%) 13.0 – 16.0 14.6 13.0 min.

Voids Filled with Asphalt (%) 65.0 – 78.0 72.8 Dust-to-Binder 0.8 – 1.6 1.2

In accordance with the test plan, the MATC Team collected six (6) loose mix samples during the production of the WFL 401 mixture for comprehensive laboratory analysis. The individual mixture samples were tested for asphalt content by ignition and gradation, as well as mixture specific gravity testing (Gmm & Gmb) to determine %VTM (air voids), %VMA, and %VFA. It's important to note that the MATC also sampled individual aggregate stockpiles and asphalt binder separately.

This was crucial for determining a correction factor for the ignition furnace used by MATC, thereby ensuring accurate measurement of the asphalt content in the production samples.

Asphalt Content & Gradation:

The asphalt content for each sample was determined using an ignition furnace, with a correction factor derived from aggregate stockpile samples obtained during the MATC's site visit. The six (6) samples obtained during the production of the WFL 401 mixture were all determined to have asphalt contents within the allowable production tolerance from the design value. The test results indicated low variability in asphalt content, with each sample's asphalt content closely approaching the Job Mix Formula (JMF) target of 5.52% and falling well within the established production tolerance range of 5.12% to 5.92%. The results from this testing are provided in Figure 3 below.

Figure 3: Asphalt Content by Ignition Results for the WFL 401 Production Mix Samples

The results of the post-ignition gradation testing show that the produced mixture stayed within the production limits, as illustrated in Figure 4 below for the 3/4”, 1/2”, #4, #30, and #200 sieve sizes. Also, as can be seen in Table 7, among the six production samples analyzed, sample S5 exhibited the lowest percent passing the #200 sieve, with a value of only 4.6%, which is 1.2% below the JMF target of 5.8%. This percentage is notably lower than that of the other production samples, which all ranged from 5.3% to 6.3% passing the #200 sieve. This decrease in percent passing the #200 sieve suggests that sample S5 may experience an increase in Voids in the Mineral

Aggregate (VMA) and result in a slight drop in mixture stability as the dust-to-binder ratio decreases, as compared to the other samples.

Figure 4: Gradation Results for the WFL 401 Production Mix Samples

Table 7: Gradation Results for the WFL 401 Production Mix Samples

Sieve Size JMF Production Limits S1 S2 S3 S4 S5 S6

1” 100.0 100 100.0 100.0 100.0 100.0 100.0 100.0

3/4" 100.0 97.0 – 100 100.0 100.0 100.0 100.0 100.0 100.0

1/2" 85.5 81.5 – 89.5 85.1 87.0 88.4 85.9 85.5 84.4

3/8” 70.0 65.0 – 75.0 69.2 73.8 73.4 68.9 71.9 69.1

#4 45.8 38.8 – 52.8 44.3 49.8 48.5 45.3 47.0 44.8

#8 31.7 26.7 – 36.7 29.0 32.3 32.4 30.7 29.6 30.2

#16 --- --- 19.8 22.3 22.5 21.7 19.8 21.3

#30 16.4 13.4 – 19.4 14.6 16.7 16.7 16.5 14.2 16.1

#50 11.3 8.3 – 14.3 10.7 12.4 12.3 12.3 10.1 12.1

#100 --- --- 7.7 8.9 8.8 8.9 7.0 8.7

#200 5.8 3.8 – 7.8 5.3 6.3 6.1 6.3 4.6 6.0

Mixture Specific Gravities & Volumetric Properties:

Based on both Maximum Specific Gravity (Gmm) and Bulk Specific Gravity (Gmb) testing of the loose mixture samples, volumetric properties were determined. As can be seen in Figure 5 below, the

Gmm test results are very consistent and, as compared to the JMF, although they are slightly higher than what was established during the mix design at the target asphalt binder content, they are all within the test method’s “d2s” tolerance for multi-lab precision. Slight increases in the Gmm value for the same asphalt binder content from mix design to production could likely be a result of asphalt binder absorption taking place during production that was not completely accounted for during the mix design phase. For an asphalt mixture at any given asphalt binder content, as asphalt binder absorption takes place the Gmm value increases due to a decrease in mixture volume. The Gmm value will stabilize once the asphalt binder absorption is complete. While the difference was only a slight increase from the JMF target, ensuring that mix design procedures properly “simulate” the asphalt absorption that is expected to occur during live production is important.

Figure 5: Gmm Results for the WFL 401 Production Mix Samples

As depicted in Figure 6, the Bulk Specific Gravity (Gmb) results demonstrate minimal variability and are closely aligned with the Job Mix Formula (JMF). Notably, Sample 5 displays a lower Gmb value and is likely a result of the lower dust percentage leading to a more “open” structure. This correlates with its lower dust percentage and the reduced Bulk Specific Gravity (Gmb) observed in comparison to the other samples. Nonetheless, these values fall within the acceptable range of the precision statement for the test method, indicating consistent production quality.

Figure 6: Gmb Results for the WFL 401 Production Mix Samples

The consistent quality of production is also reflected in the Voids in Total Mix (VTM) percentages, illustrated in Figure 7. When considering both Gmm and Gmb values, all production samples, except

Sample 5, exhibited VTM values that closely approached the mix design target of 4.0%. Again, this higher %VTM in Sample 5 is likely driven by the lower dust percentage creating a more “open” structure, leading to a lower Gmb value, and resulting in a higher air voids content.

Figure 7: %VTM Results for the WFL 401 Production Mix Samples

To calculate the Voids in Mineral Aggregate (VMA) for the production samples, the Gmb from laboratory compaction is used. The calculated values for the VMA were very close to the JMF target of 14.2%, and well above the Lower Production Limit of 13.0%, as seen in Figure 8. Again, it should be noted that Sample 5 did result in a higher %VMA, as compared to the other samples, and is likely a result of its lower %Passing the #200 sieve noted earlier.

Figure 8: %VMA Results for the WFL 401 Production Mix Samples

Also, the Voids Filled with Asphalt (VFA) for each production sample is calculated using both the

%VTM and the %VMA. As seen in Figure 9 below, all production samples were within the mix design limits of 65% to 78% for VFA. Again, because of its higher %VMA, Sample 5 is very close to the lower design limit with a %VFA of 65.9%.

Figure 9: %VFA Results for the WFL 401 Production Mix Samples

Mixture Performance Tests

To assess the performance characteristics of the WFL 401 surface mixture, comprehensive testing was conducted, encompassing cracking, rutting, and durability analyses on both the Mix Design and

Production Mix samples. Cracking resistance was evaluated using the IDEAL Cracking Test (IDEAL-

CT), while rutting potential was determined through the IDEAL Rutting Test (IDEAL-RT) and the

Hamburg Wheel Tracking Test (HWTT). Additionally, to further evaluate durability, the asphalt mixtures underwent long-term conditioning designed to replicate the equivalent of 12 years of field aging post construction based on the current recommendation found in the draft AASHTO Standard

Practice for Long-Term Laboratory Conditioning of Asphalt Mixtures.

Conditioning and fabrication of all test samples followed specific guidelines to minimize variability while allowing for reproducibility during sampling, reheating, splitting, fabricating, and testing. The mix design samples were produced entirely in the laboratory, so these samples followed the standard AASHTO R 30 protocol which required the samples to be short-term oven aged for 2 hours at compaction temperature after mixing and prior to fabrication. However, for the mix design samples that were used for “Aged” IDEAL-CT testing, a long-term aging protocol was followed which required the samples to be exposed to an additional 20 hours at 105°C prior to fabrication.

For the production samples, all samples were obtained in 5-gallon buckets and allowed to cool to ambient temperature overnight before splitting down to test replicate sizes. When an individual bucket sample was ready to be split, first it was placed in an oven at 140°C for 3 hours to allow the mixture to heat up and become workable for splitting by the quartering method. Once the samples are reduced to testing size, they were immediately placed back in the oven at compaction temperature and as soon as the temperature was reached, fabrication began. Again, for the production samples that were used for “Aged” IDEAL-CT testing, after reducing to testing size, the samples were first allowed to cool to room temperature before being placed in an oven and exposed to the same long-term aging protocol as the mix design samples.

Detailed discussions of each mechanical test and their respective results for the surface mixtures are presented in the subsequent sections. It should be noted that all performance tests were carried out on specimens compacted to achieve a target air void content of 7.0% ± 0.5%.

IDEAL Cracking Test

The IDEAL Cracking Test (IDEAL-CT) is an assessment that can be routinely used in the process of mix design and quality assurance to determine the cracking resistance of asphalt mixtures. The Cracking

Tolerance Index (CTIndex) parameter derived from this test provides insight into the susceptibility of the asphalt mix to cracking. This index parameter is influenced by several factors, including the composition of the asphalt mix, the content of reclaimed asphalt pavement (RAP), air voids, and the aging conditions of the material. The CTIndex is calculated using equations 1 and 2 as provided below.

Figure 10 below shows the IDEAL-CT being performed.

𝑮𝑮𝒇𝒇 =

𝑾𝑾𝒇𝒇

𝑫𝑫 × 𝒕𝒕

× 𝟏𝟏𝟏𝟏𝟔𝟔 ………………………………………… (1)

Where:

Gf = Failure Energy (Joules/m2)

Wf = Work of Failure (Joules)

D = Specimen Diameter (mm), and t = Specimen Thickness (mm)

𝑪𝑪𝑪𝑪𝑰𝑰𝑰𝑰𝑰𝑰𝑰𝑰𝑰𝑰 =

𝒕𝒕 𝟔𝟔𝟔𝟔 𝒍𝒍𝟕𝟕𝟕𝟕

𝑫𝑫

𝑮𝑮𝒇𝒇

|𝒎𝒎𝟕𝟕𝟕𝟕| × 𝟏𝟏𝟏𝟏𝟔𝟔 …………………………………………. (2)

Where:

CTIndex = Cracking Tolerance Index

Gf = Failure Energy (Joules/m2)

|m75| = Absolute Value of the post-peak slope m75 (N/m) l75 = Displacement at 75% the peak load after the peak (mm)

D = Specimen Diameter (mm), and t = Specimen Thickness (mm)

Figure 10: IDEAL-CT Test Setup

Under the test plan, the IDEAL-CT was performed on five cylindrical specimens, each 150mm diameter by 62mm height with a controlled loading rate of 50mm/min and a testing temperature of 25°C. Tests were performed on each of the six different production samples, denoted as S1 through S6, and compared against the approved Mix Design. To assess long-term aged performance, samples of loose mix were conditioned at 105°C for 20 hours, simulating 12 years field aging of an asphalt layer at a depth of 2 inches below the pavement surface. This aging protocol was conducted on mix design samples as well as Production Mix samples S2, S4, and S6, to evaluate the mixture’s resistance to long-term cracking. The average CTIndex values obtained for each of the individual samples is shown below in Figure 11, while the average results for the comparison between Mix Design (with and without aging) and Production Mix (with and without aging) is summarized in Table 8.

Figure 11: IDEAL-CT Test Results

Table 8: Average IDEAL-CT Testing Results

Mixture ID CTIndex Std. Dev. COV

Mix Design 239.0 61.0 25.5% Production Mix S1 287.6 69.1 24.0% Production Mix S2 241.4 76.6 31.7% Production Mix S3 256.4 51.1 19.9% Production Mix S4 246.2 30.3 12.3% Production Mix S5 414.8 113.5 27.4% Production Mix S6 286.2 40.8 14.3%

Mix Design (w/Aging) 168.3 33.8 20.1% Production Mix S2 (w/Aging) 143.8 23.7 16.5% Production Mix S4 (w/Aging) 128.0 23.2 18.1% Production Mix S6 (w/Aging) 203.4 64.4 31.7%

Notably, Production Mix samples S1 through S6 showcased higher CTIndex values in comparison to mix design CTIndex. Particularly, Production Mix sample S5 demonstrated an elevated CTIndex, as compared with the other samples, which could likely be a result of its lower Dust-to-Binder ratio and higher VMA, as observed in the volumetric analysis. This decrease is mix stiffness resulting from a lower dust percentage could account for its increased CTIndex value. “Aged” CTIndex testing resulted in a 30% reduction in cracking resistance for the mix design and an average 40% reduction for production samples. The chart in Figure

11 above also includes error bars which represent the standard deviation, highlighting the variability in the CTIndex among the samples. The coefficient of variation (COV) values for the IDEAL-CT replicates were around 20%-25%, which is slightly higher than the typically observed within sample COV of 15%-20%.

Figure 12 presents an interaction diagram that juxtaposes the Failure Energy (Gf) with the Slope

Parameter (l75/m75) for testing replicates from both Production Mix sample S1 and the mix design, illustrating how these variables contribute to the resultant CTIndex value. The CTIndex values are demarcated by the dashed contour lines. This visual analysis reveals that the CTIndex is primarily driven by the Slope

Parameter (l75/m75). While the Failure Energy (Gf) for the testing replicates of both Production Mix sample

S1 and Mix Design is relatively consistent, variability within the slope parameter among the replicates significantly influences the CTIndex values. This variability is likely the cause of the higher standard deviation observed in the CTIndex for both sample sets.

Figure 12: IDEAL-CT (Gf vs l75/m75) Interaction Diagram

IDEAL Rutting Test

The IDEAL Rutting Test (IDEAL-RT) is used to determine asphalt mixture rutting resistance at high temperatures that can range between 35°C and 65°C, depending on local climate. It can be implemented for use in mix design and quality assurance testing. The RTIndex parameter obtained from this test is reported to be sensitive to key asphalt mix components and volumetric properties including RAP, binder content, air voids and aging conditions. RTIndex parameter is calculated using equations 3 and 4 as provided below. Figure 13 shows the IDEAL-RT test being performed.

𝑹𝑹𝑪𝑪𝑰𝑰𝑰𝑰𝑰𝑰𝑰𝑰𝑰𝑰 = 𝟔𝟔.𝟔𝟔𝟏𝟏𝟔𝟔 × 𝟏𝟏𝟏𝟏−𝟕𝟕 ×

𝝉𝝉𝒇𝒇

𝟏𝟏 𝑷𝑷𝑷𝑷

………………………………………… (3) 𝝉𝝉𝒇𝒇 = 𝟏𝟏.𝟑𝟑𝟕𝟕𝟔𝟔 ×

𝑷𝑷𝒎𝒎𝑷𝑷𝑰𝑰

𝒕𝒕 × 𝒘𝒘

…………………………………………. (4)

Where:

RTIndex = Rutting Tolerance Index τf = Shear Strength (Pa)

Pmax = Maximum Load (N) t = Specimen Thickness (m) w = Width of the Upper Loading Strip (0.0191 m)

Figure 13: IDEAL-RT Test Setup

The IDEAL-RT was performed on five replicated 150mm diameter by 62mm high cylindrical specimens, with a loading rate of 50mm/minute, and a 50°C test temperature. The average RTIndex values obtained for each of the individual production samples is shown in Figure 14, and the average test results for both the Mix Design and Production Mix samples is summarized in Table 9.

Figure 14: IDEAL-RT Test Results

Table 9: Average IDEAL-RT Testing Results

Mixture ID RTIndex Std. Dev. COV

Mix Design 50.8 6.9 13.6% Production Mix S1 57.5 2.2 3.8% Production Mix S2 61.7 5.4 8.8% Production Mix S3 46.2 2.2 4.7% Production Mix S4 49.6 2.6 5.2% Production Mix S5 54.9 2.2 4.0% Production Mix S6 58.6 3.2 5.5%

In general, the average Rutting Tolerance Index (RTIndex) for the six production samples was 54.7 and was close to the average mix design value of 50.8. This value can be considered typical for a mixture utilizing a PG58 binder based on the criterion that is currently being suggested by the test developers. The observed standard deviations are relatively small, reinforcing the reliability of the observed trends.

Hamburg Wheel Tracking Test

The Hamburg Wheel Tracking Test (HWTT) was performed to determine the permanent deformation and moisture damage (i.e., stripping) properties of the asphalt mixtures. The Hamburg

Wheel Tracking Tester (HWTT) is shown in Figure 15 below. HWTTs were conducted on both the

Mix Design and three different Production Mix samples (two replicates for each case), and at different desired test temperatures. Two of the Production Mix samples, S1 and S3, were tested at 45°C, while the Mix Design and the third Production Mix sample, S5, were tested at 50°C, each with a testing limit of either 12.5mm rut depth or 20,000 passes, whichever occurred first.

Figure 15: Hamburg Wheel Tracking Tester

As can be seen in Figure 16 below, both the Mix Design and Production Mix samples S1 and S3 performed well in the HWTT and completed the standard 20,000 passes, however, Production Mix sample S5 failed after 19,848 passes. It should be noted, as shown in the figure, that the failing test of sample S5 was only in the Left Wheel Path (LWP) replicates. The replicates in the Right

Wheel Path (RWP) had a rut depth at the completion of the test cycles of only 3.8mm, which compared more similarly to the Mix Design tests that were also conducted at 50°C. The average final rut depths for Production Mix samples S1 and S3 were 2.9mm and 3.6mm, respectively. Again, these two production samples were tested at 45°C.

Figure 16: Hamburg Wheel Tracking Test Results

For comparison, post-test images can be seen in both Figure 17 and Figure 18 of the left and right wheel paths of both sample S1, tested at 45°C, and sample S5, tested at 50°C. When looking at the images, there is a noticeable difference in the clarity of the water between the two test runs.

The dirtier water seen in the S5 images is likely evidence that some level of stripping was occurring in those test samples as compared to the S1 images.

Figure 17: Post-Test Images of Production Mix Sample S1 Tested at 45°C

Figure 18: Post-Test Images of Production Mix Sample S5 Tested at 50°C

Also, when looking at the rutting plots for S5, as seen in Figure 19, while inconclusive, there does appear to be the indication of a potential “stripping inflection point” occurring around 15,000 cycles for the LWP replicates. When comparing Production Mix samples S1 and S5, there is obviously a difference in testing temperature that is likely playing a role, however, it should be noted again that like sample S5, the Mix Design samples were also tested at 50°C but performed well and did not show signs of stripping. The other possibility that should be considered is that

Production Mix sample S5 is the same sample that showed a low dust percentage, and since the

Job Mix Formula required 1% Lime be added to reduce the…