Pooled Fund Partners

Institute for Transportation

Institute for Transportation
2711 South Loop Dr, Suite 4700
Ames, IA 50010-8664

Phone: 515-294-8103
Fax: 515-294-0467
E-mail: InTrans Communications

Copyright © 2018, Iowa State University. All rights reserved.

Study Background

The use of recycled asphalt shingles (RAS) in hot-mix asphalt (HMA) applications has grown across the US over the last 10 years. Although the majority of states are using post-manufactured RAS, there has been a rapidly growing intere the use and applications of post-consumer (tear-off) RAS in asphalt applications. Many state researchers and bitum material engineers share common concerns and questions in the use of post-consumer RAS in asphalt applications and require additional research to better understand the effects of post-consumer RAS on the performance of aspha pavements and their economic value. Multiple state demonstration projects provide adequate laboratory and field te results to more comprehensively answer the design, performance and environmental questions/concerns remaining produce a high quality mix design to ensure long-term pavement performance.

The study addresses the concerns of quality assurance (QA)/ quality control (QC) in the sourcing, processing and incorporation of the RAS to achieve a quality end product to meet state requirements for use in state asphalt applica The study team will works closely with state partners to develop specifications that include sufficient language to co the QA/QC concerns.

State demonstration projects will provide the research team with samples for needed laboratory testing and data to support the research results needed to determine the behavior and performance of RAS in state asphalt pavements varying percentages, climates and traffic levels.

This is a two-year, pooled fund study, starting in 2009. The study kick-off meeting was held in October 2009 and in state partners from Indiana DOT, Iowa DOT, Minnesota DOT, Missouri DOT, Wisconsin DOT and a representative fro Illinois Tollway. In 2010, CalTrans, Colorado DOT and Illinois DOT joined in this important research and the study w extended a year, until October 2012, to allow joining states a full two years to complete their demonstration project research. The final report will include two reports: the first report will include state research completed under the fir two years (IA, IN, MN and MO) and the second report will include states completing their research over the last two (CA, CO, IL and WI).

Study Tasks

  1. Literature Review
  2. Review and implement QA/QC of equipment and best practices for processing and sourcing of shingles for state partner demonstration projects
  3. Condition Surveys of completed demonstration projects
  4. Laboratory Research:
    1. Characterization of binder qualities
    2. Mix design and performance testing
  5. Statistical analysis
  6. Technology Transfer
  7. Final Report

Study Objectives

The following study objectives were identified by the state partners to address the recycled asphalt shingle (RAS) factors as follows:

High Priority Moderate Priority
RAS Content Polymer Modified Asphalts/GTR Asphalts
Available RAS AC Content Virgin Binder Grade
Warm Mix Asphalt with RAS/RAP Stockpile Variability
RAS Grind Size Variations Organic vs. Fiberglass RAS
Post-Manufactured vs. Post-Consumer

Additional study factors include, plant configuration, moisture content, mix design procedures using RAS, shingle production process technology and methods of determining the deleterious content. Laboratory research consists of volumetric data, moisture sensitivity testing, binder grading and mix performance tests.

Participating states will complete demonstration projects to address RAS Factors and laboratory research will be completed for each demonstration project.