SWUTC Research Project Description

Title of Project:  Performance Evaluation & Mix Design for High RAP Mixtures

Project Number: 0-6092

Principal Investigator:
Fujie Zhou
(979) 458-3965
P.I. Affiliation:  Texas A&M University
f-zhou@ttimail.tamu.edu

Project Monitor:
Robert Lee
Texas Department of Transportation
(512) 506-5939
rlee@dot.state.tx.us

Project Status:  Active

Date Started:  9/1/08

Estimation Completion Date:  8/31/11

Estimated Cost - Current Fiscal:  $139,215

Estimated Cost - Total Planned:  $387,975

Project Summary:
Project Abstract:
Economical benefits of using recycled asphalt pavement (RAP) are well known, but TxDOT should only consider using it if;

1. its long-term performance is judged to be the same or better than the conventional mix.
2. the quality/uniformity of the RAP layer can be certified on a day to day basis, and
3. for the surface layers containing RAP adequate skid resistance must be maintained as compared to conventional mix using Class A aggregates.

This project will lay the foundation for addressing all three of these critical factors.

Project Objectives:
The main objective of this project will be to address and develop good practices for designing and constructing mixes containing higher than normal RAP contents. Past experiences have found that high RAP contents can potentially lead to very stiff HMA mixes and in some instances virgin binders have been found to be incompatible with the existing aged binder. These issues will be addressed in the proposed work plan.

Task Descriptions:
Task 1. Literature Search on Best Practice for RAP Materials

Task 2. Best Practices for RAP Processing/Fractionating and Stockpile Management in Texas

Task 3. Texas Regional Characteristics of Fractionated RAP Characterization (Binder, Aggregate, and Moisture Content)

Task 4. New Methods of Evaluating the Properties/Grade of the RAP Binder

Task 5. Develop and Teach a Workshop on RAP Processing and Mix Design

Task 6. Evaluation of the Combined Binder (Binder from RAP and New Binder) Properties

Task 7. A Balanced Mix Design Method for High RAP Mixes

Task 8. Performance Evaluation of High-RAP Mixes

Task 9. Field Experimental RAP Mix Test Sections

Task 10. Guidelines for RAP Quality and Processing in the Field

Task 11. Draft Specs for Use of High RAP Mixes in Surface, Binder, and Base Course

Task 12. A Life-cycle Cost Analysis with Focus on Sensitivity Analysis of RAP Content

Task 13. Reports

Index Terms:
Asphalt pavements, Recycled asphalt pavement, Pavement performance, Pavement layers, Hot mix paving mixtures, Mix design, Reclaimed asphalt pavement, Texas, Research projects