Stacey D. Diefenderfer, Ph.D., P.E.
Associate Principal Research Scientist
Research Interests:
- 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:
- Registered 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:
- VTRC Jack H. Dillard Best Paper Award, "Mechanistic-Based Evaluation of Performance Thresholds for Balanced Mix Design Asphalt Surface Mixtures" (with Habbouche, Boz, Underwood and Othman), 2024
- VTRC Jack H. Dillard Best Paper Award, "Simple and Practical Tests for Rutting Evaluation of Asphalt Mixtures in the Balanced Mix Design Process" (with I. Boz and J. Habbouche), 2023
- VTRC Tilton E. Shelburne Award, 2022
- VTRC Jack H. Dillard Best Paper Award, "Balanced Mix Design for Surface Asphalt Mixtures: Phase I: Initial Roadmap Development and Specification Verification" (with I. Boz and J. Habbouche), 2021
- W. J. Eammons Award for Best Paper, Association of Asphalt Paving Technologists, 2016
- VTRC Jack H. Dillard Best Paper Award, 2015
- VCTIR Horizon Award for Outstanding Productivity and Achievement, 2014
- Outstanding Young Alumni Award, Via Department of Civil and Environmental Engineering, Virginia Tech, 2013
- VDOT Commissioner's Award for Outstanding Achievement - Innovation and Quality Improvement, 2011
- VCTIR Horizon Award for Outstanding Productivity and Achievement, 2011
- VTRC Jack H. Dillard Best Paper Award, 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
Current Projects
-
Field Performance of High RAP Mixtures
Project No: 126826 -
Developing a Balanced Mix Design (BMD) Framework for SBS Modified Dense-Graded Asphalt Surface Mixtures – Phase I
Project No: 124333 -
Sustainable Surface Mixtures Incorporating Recycled Plastic Waste and High RAP Contents
Project No: 122604 -
Documentation of 2024 Balanced Mix Design Implementation
Project No: 126084 -
Field Validation of Balanced Mix Design Initial Criteria
Project No: 124332
Reports
-
Fatigue Life Characterization of Superpave Mixtures at the Virginia Smart Road
Report No: 06-CR1 -
Detection of Polymer Modifiers in Asphalt Binder
Report No: 06-R18 -
Creep and Fatigue Characteristics of Superpave Mixtures
Report No: 06-R5 -
Asphalt Materials Characterization in Support of Implementation of the Proposed Mechanistic-empirical Pavement Design Guide
Report No: 07-CR10 -
Installation of Warm Mix Asphalt Projects in Virginia
Report No: 07-R25 -
Evaluation of Using Higher Percentages of Recycled Asphalt Pavement in Asphalt Mixes in Virginia
Report No: 08-R22 -
Laboratory Evaluation of a Warm Asphalt Technology for Use in Virginia
Report No: 09-R11 -
Performance of Virginia’s Warm-Mix Asphalt Trial Sections
Report No: 10-R17 -
Analysis of the Mechanistic-Empirical Pavement Design Guide Performance Predictions: Influence of Asphalt Material Input Properties
Report No: 11-R3 -
Asphalt Material Design Inputs for Use with the Mechanistic-Empirical Pavement Design Guide in Virginia
Report No: 12-R6 -
Installation and Laboratory Evaluation of Alternatives to Conventional Polymer Modifications for Asphalt
Report No: 15-R15 -
Asphalt Mixture Performance Characterization Using Small-Scale Cylindrical Specimens
Report No: 15-R26 -
Developing a Laboratory Protocol for Asphalt Binder Recovery
Report No: 15-R7 -
Evaluation of Stone-Matrix Asphalt Mixtures Containing Recycled Asphalt Shingles (RAS)
Report No: 17-R22 -
Performance of Foamed Warm Mix Asphalt In Virginia Over Four to Six Years
Report No: 18-R12 -
Evaluation of Highly Polymer-Modified Asphalt Mixtures: Phase I
Report No: 18-R14 -
Investigation of Binder Aging and Mixture Performance in Service: Reclaimed Asphalt Pavement Mixtures
Report No: 18-R26 -
Ten-Year Assessment of Virginia's First Warm Mix Asphalt Sites
Report No: 19-R18 -
Assessing Increased Use of Reclaimed Asphalt Pavement in Asphalt Mixtures
Report No: 20-R9 -
Balanced Mix Design for Surface Asphalt Mixtures: Phase I: Initial Roadmap Development and Specification Verification
Report No: 21-R15 -
Balanced Mix Design for Surface Asphalt Mixtures: 2019 Field Trials
Report No: 21-R21 -
Round Robin Testing Program for the Indirect Tensile Cracking Test at Intermediate Temperature: Phase I
Report No: 22-R3 -
Simple and Practical Tests for Rutting Evaluation of Asphalt Mixtures in the Balanced Mix Design Process
Report No: 23-R11 -
Balanced Mix Design for Surface Mixtures: 2020 Field Trials
Report No: 23-R13 -
Balanced Mix Design for Surface Mixtures: 2021 and 2022 Plant Mix Schedule Pilots
Report No: 23-R19 -
Impact of Production Variability on Balanced Mix Designs in Virginia
Report No: 23-R20 -
Interlaboratory Study for the Indirect Tensile Cracking Test at Intermediate Temperature: Phase II
Report No: 23-R3 -
Asphalt Mixture Variability and Its Effect on Balanced Mix Design Testing from Design to Production
Report No: 25-R1 -
Interlaboratory Study for the Indirect Tensile at High Temperature Test and Ideal Rutting Test
Report No: 25-R14 -
Increasing Regional Truck Freight Planning in Virginia
Report No: 25-R15 -
Evaluation of BMD Surface Mixtures with Conventional and High RAP Contents Under Laboratory-Scale and Full-Scale Accelerated Testing
Report No: 25-R16 -
A Practical Oven-Aging Method for Evaluating Long-Term Cracking Performance of Asphalt Mixtures in Virginia
Report No: 26-R04 -
Evaluation of Fiber-Modified Asphalt Mixtures Using BMD Tests
Report No: 26-R05 -
Mechanistic-Based Evaluation of Performance Thresholds for Balanced Mix Design Asphalt Surface Mixtures
Report No: 26-R08
Team Membership
Last updated: August 2, 2025