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Stacey D. Diefenderfer, Ph.D., P. E.
Associate Principal Research Scientist

Phone: (434) 293-1933
Email: Stacey.Diefenderfer@VDOT.Virginia.gov

Research:

Asphalt materials characterization, evaluation, performance and design
Balanced mix design (BMD)
Reclaimed asphalt pavement (RAP)
Warm mix asphalt (WMA)
Flexible pavement design and analysis

Education:

Ph.D. - Civil Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA
M.S., Civil Engineering, Virginia Polytechnic Institute and State University
B.S., Civil Engineering, Virginia Polytechnic Institute and State University

Registration:

Professional Engineer, Commonwealth of Virginia

Memberships:

FHWA Asphalt Pavement and Materials Technical Feedback Group
FHWA Warm Mix Technical Working Group (2009 – 2012)
Transportation Research Board

Chair - AFK30 Non-binder Components of Asphalt Mixtures (2015 – 2020)
Chair - AKM30 Asphalt Materials Selection and Mix Design (2020-2021)
Member - AFK20 Asphalt Binders (2005-2017)
Member - AFK30 Non-binder Components of Asphalt Mixtures (2007-2015)
Member - AFK50 Structural Requirements of Asphalt Mixtures (2012-2020)
Member - AKM30 Asphalt Materials Selection and Mix Design (2021-2022)
Member - AKM40 Asphalt Mixture Evaluation and Performance (2021-2022)

National Cooperative Highway Research Program (NCHRP)

Panel 09-22 Beta Testing and Validation of HMA PRS
Panel 09-49 Performance of WMA Technologies: Stage I -- Moisture Susceptibility
Panel 09-49A Performance of WMA Technologies: Stage II - Long Term Performance
Panel 09-50 Performance Related Specification for Asphaltic Binders Used in
Preservation of Surface Treatments
Chair - Panel 09-55 Recycled Asphalt Shingles in Asphalt Mixtures with Warm Mix
Asphalt Technologies
Panel DTFRS-01 TFRS Project Panel on Quality (QA) Aspects of Performance Related
Specifications (PRS)
Chair – Panel 09-68 Recycled Asphalt Materials: Binder Availability and Its Impact on
Mix Performance
Synthesis Panel 50-14 Practices for Fabricating Asphalt Specimens for Performance
Testing in Laboratories
Synthesis Panel 52-17 Use of Recycling Agents in Asphalt Concrete Mixtures

Association of Asphalt Paving Technologists

Board of Directors - Director at Large
Board Liaison – Newer Member Committee
Member – Membership Committee

ASTM International – Member

Member – Committee D04 Road and Paving Materials
Member – Subcommittee D04.21 Specific Gravity and Density of Asphalt Mixtures
Member – Subcommittee D04.26 Fundamental/Mechanistic Tests
Member – Subcommittee D04.30 Methods of Sampling

International Society for Asphalt Pavements (ISAP)

Awards:

W.J. Eammons Award for Best Paper, Association of Asphalt Paving Technologists, 2016
Jack H. Dillard Best Paper Award, VTRC, 2015
Horizon Award for Outstanding Productivity and Achievement, VCTIR, 2014
Outstanding Young Alumni Award, Via Department of Civil and Environmental Engineering, Virginia Tech, 2013
Commissioner's Award for Outstanding Achievement - Innovation and Quality Improvement, 2011
Horizon Award for Outstanding Productivity and Achievement, VCTIR, 2011
Jack H. Dillard Best Paper Award, VTRC, 2006
Dean's List for Teaching Excellence, College of Engineering, Virginia Tech, Spring 2000
Charles E. Via Doctoral Fellowship, Charles E. Via Department of Civil and Environmental Engineering, Virginia Tech, Fall 1999 - Spring 2003
Dean's List for Teaching Excellence, College of Engineering, Virginia Tech, Spring 2000
Outstanding Young Alumni Award, Via Department of Civil and Environmental Engineering, Virginia Tech, 2013

Team Memberships:

Pavements

Projects:

122604 - Sustainable Surface Mixtures Incorporating Recycled Plastic Waste and High RAP Contents - Co-Principal Investigator

124332 - Field Validation of Balanced Mix Design Initial Criteria - Co-Principal Investigator

122013 - Developing Long-term Aging Protocols for Cracking Performance Evaluation of Asphalt Mixtures in Virginia - Co-Principal Investigator

120747 - Mechanistic-Based Evaluation of Performance Thresholds for Engineered Surface Asphalt Mixtures - Co-Principal Investigator

122349 - Balanced Mix Design for Surface Asphalt Mixtures: Fiber-Modified Mixtures - Co-Principal Investigator

124200 - Evaluation of Balanced Mix Design (BMD) Surface Mixtures with Conventional and High RAP Contents under Laboratory-Scale and Full-Scale Accelerated Pavement Testing (APT) - Co-Principal Investigator

121388 - Inter-Laboratory Study for the Indirect Tensile Test at High Temperature and Rapid Rutting Test - Co-Principal Investigator

119819 - Balanced Mix Design for Surface Asphalt Mixtures: 2021 and 2022 Plant Mix Schedule Pilots - Principal Investigator

116425 - Impact of Production Variability on Balanced Mix Design in Virginia - Principal Investigator

119857 - Balanced Mix Design for Surface Asphalt Mixtures: 2020 and 2021 Field Trials - Principal Investigator

117336 - Feasibility of Using Monotonic Loading-based Tests to Evaluate Rutting Performance of Asphalt Mixtures - Co-Principal Investigator

118733 - Round Robin Testing Program for the Indirect Tensile Cracking Test (IDT-CT) at Intermediate Temperature - Co-Principal Investigator

115763 - Balanced Mix Design for Asphalt Mixtures: High RAP Field Trials - Principal Investigator

112037 - Performance Mixture Design for Asphalt Mixtures: Phase I, Roadmap and Specification Development - Co-Principal Investigator

101902 - Investigation of Binder Aging and Mixture Performance In-Service Recycled Asphalt Pavement (RAP) Mixtures - Co-Principal Investigator

106481 - Evaluation of Highly Polymer-Modified Asphalt Mixtures - Co-Principal Investigator

101903 - Continuing Performance of Warm-Mix Asphalt in Virginia - Principal Investigator

94209 - Asphalt Material Characteristics for Use with the MEPDG - Co-Principal Investigator

86812 - ‘Mechanistic-Empirical Pavement Design Guide’ Sensitivity Analysis: Binder Properties - Principal Investigator

87460 - Warm Mix Asphalt Performance - Principal Investigator

80577 - Laboratory Evaluation of Warm Asphalt for Use in Virginia - Principal Investigator

85364 - Evaluation of Using Higher Percentage of Rap in Asphalt Mixes in Virginia - Co-Principal Investigator

78286 - Asphalt Materials Characterization in Support of Implementation of the Proposed Mechanistic-Empirical Pavement Design Guide - Co-Principal Investigator

75399 - Detection of Polymer Modifiers in Asphalt Binder - Principal Investigator

75398 - Permanent Deformation and Fatigue Characteristics of Superpave Mixtures - Principal Investigator

Publications:

23-R3 - Interlaboratory Study for the Indirect Tensile Cracking Test at Intermediate Temperature: Phase II

23-R20 - Impact of Production Variability on Balanced Mix Designs in Virginia

23-R19 - Balanced Mix Design for Surface Mixtures: 2021 and 2022 Plant Mix Schedule Pilots

23-R13 - Balanced Mix Design for Surface Mixtures: 2020 Field Trials

23-R11 - Simple and Practical Tests for Rutting Evaluation of Asphalt Mixtures in the Balanced Mix Design Process

22-R3 - Round Robin Testing Program for the Indirect Tensile Cracking Test at Intermediate Temperature: Phase I

21-R21 - Balanced Mix Design for Surface Asphalt Mixtures: 2019 Field Trials

21-R15 - Balanced Mix Design for Surface Asphalt Mixtures: Phase I: Initial Roadmap Development and Specification Verification

20-R9 - Assessing Increased Use of Reclaimed Asphalt Pavement in Asphalt Mixtures

19-R18 - Ten-Year Assessment of Virginia's First Warm Mix Asphalt Sites

18-R26 - Investigation of Binder Aging and Mixture Performance in Service: Reclaimed Asphalt Pavement Mixtures

18-R14 - Evaluation of Highly Polymer-Modified Asphalt Mixtures: Phase I

18-R12 - Performance of Foamed Warm Mix Asphalt In Virginia Over Four to Six Years

17-R22 - Evaluation of Stone-Matrix Asphalt Mixtures Containing Recycled Asphalt Shingles (RAS)

15-R7 - Developing a Laboratory Protocol for Asphalt Binder Recovery

15-R26 - Asphalt Mixture Performance Characterization Using Small-Scale Cylindrical Specimens

15-R15 - Installation and Laboratory Evaluation of Alternatives to Conventional Polymer Modifications for Asphalt

12-R6 - Asphalt Material Design Inputs for Use with the Mechanistic-Empirical Pavement Design Guide in Virginia

11-R3 - Analysis of the Mechanistic-Empirical Pavement Design Guide Performance Predictions: Influence of Asphalt Material Input Properties

10-R17 - Performance of Virginia’s Warm-Mix Asphalt Trial Sections

09-R11 - Laboratory Evaluation of a Warm Asphalt Technology for Use in Virginia

08-R22 - Evaluation of Using Higher Percentages of Recycled Asphalt Pavement in Asphalt Mixes in Virginia

07-R25 - Installation of Warm Mix Asphalt Projects in Virginia

07-CR10 - Asphalt Materials Characterization in Support of Implementation of the Proposed Mechanistic-empirical Pavement Design Guide

06-R5 - Creep and Fatigue Characteristics of Superpave Mixtures

06-R18 - Detection of Polymer Modifiers in Asphalt Binder

06-CR1 - Fatigue Life Characterization of Superpave Mixtures at the Virginia Smart Road