Testing Protocols to Ensure Performance of High Asphalt Binder Replacement Mixes Using RAP and RAS

Submitter: Peggy Currid

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https://hdl.handle.net/2142/88680 Copy

Description

Title

Testing Protocols to Ensure Performance of High Asphalt Binder Replacement Mixes Using RAP and RAS

Contributor(s)

• Al-Qadi, Imad L.
• Ozer, H.
• Lambros, J.
• El Khatib, A.
• Singhvi, P.
• Khan, T.
• Rivera-Perez, J.
• Doll, B.

Issue Date

2015-12

Keyword(s)

• asphalt binder replacement
• asphalt concrete
• flexibilityindex
• Illinois modified semi-circular bending test
• pavement performance
• reclaimed asphalt shingles
• recycled asphalt pavement

Abstract

The use of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in AC mixtures can reduce demand for virgin aggregates and asphalt binder, bringing environmental and economic benefits. However, replacing virgin asphalt binder in asphalt concrete (AC) mixtures poses challenges in terms of mixture volumetrics and low-temperature cracking, fatigue cracking, and other deterioration related to cracking. To counter these effects, softer virgin asphalt binder grades or modifying agents are used to improve production consistency. The purpose of this study was to develop and evaluate protocols, procedures, and specifications for testing engineering properties and performance of AC mixtures with high amounts (up to 60%) of RAP and RAS. The criteria for selection of the test method were (1) statistically significant spread in test outcome, representing a mix’s cracking resistance; (2)applicability and seamless implementation; (3) correlation to other independent test methods and engineering intuition; and (4) correlation to field performance. A practical test method, the Illinois modified semi-circular bending test (IL-SCB) was developed that can be readily implemented to quantify AC mixture’s cracking potential. In addition,a flexibility index (FI) was introduced to determine cracking resistance in a consistent way. The IL-SCB showed consistent and repeatable trends for changes in AC mix design properties. The developed FI was shown to provide greater separation between AC mixes to capture some of the changes that could not be captured by fracture energy alone. This approach does not enforce any limits on any AC mixture design characteristics, such as RAP and RAS content, or other alternative materials or technologies. Instead, it categorizes AC mixes based on their performance index. Hence, this approach encourages innovation and sustainability at the same time.

Publisher

Illinois Center for Transportation/Illinois Department of Transportation

Series/Report Name or Number

Illinois Center for Transportation Series No. 15-017

ISSN

0197-9191

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/88680

Sponsor(s)/Grant Number(s)

Illinois Department of Transportation, R27-128

Copyright and License Information

No restrictions. This document is available to the public through the National Technical Information Service,Springfield, Virginia 22161

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