Thesis
Laboratory evaluation of hot and warm mixtures with high reclaimed asphalt pavement contents
University of Iowa
Master of Science (MS), University of Iowa
Spring 2025
DOI: 10.25820/etd.007837
Abstract
Recently, reclaimed asphalt pavement (RAP) materials have become a focal point in transportation materials research due to their economic and environmental benefits. Adding RAP materials to mixes introduces age-hardened binder, which tends to enhance rutting resistance but reduces cracking resistance--a critical concern in colder climates. To address these challenges, various testing procedures have been performed.
This study aimed to evaluate the effects of various RAP concentrations and binder additives on asphalt performance, as well as comparing two cracking test methods. Mixes with RAP contents of 0%, 20%, 30%, 40%, and 50% were prepared and two different binder additives were used. One additive, called Zero-M, is a cool mix additive designed for use for lower mixing and compaction temperatures. The second, called Anova, is a vegetable oil-based rejuvenator. For each mix design, a minimum of twelve specimens were prepared for testing. The specimens were tested for rutting resistance using the Hamburg Test and for cracking resistance using the Illinois Flexibility Index Test (I-FIT) and the Indirect Tensile Asphalt Cracking Test (IDEAL- CT). Each of the cracking tests produced their own indicators, the Flexibility Index (FI) and the CT index, that represent the performance of the tested specimen.
The test results confirmed that increasing RAP content improves rutting resistance but reduces cracking resistance, with significant performance changes observed from 0% to 20% RAP and leveling off around 40%. The addition of the Zero-M cool mix additive improved cracking resistance across all RAP contents but reduced rutting resistance. Similarly, the Anova rejuvenator also improved cracking resistance but reduced rutting resistance.
In comparing the two cracking tests, both were found to have their respective pros and cons. The IDEAL-CT test has a simpler specimen preparation and procedure while also yielding a lower coefficient of variation than that of the I-FIT test. On the other hand, the I-FIT test produced four test specimens from one compacted mixture that produces one IDEAL-CT specimen, thus providing four testing results from one mix. While the additional data is beneficial, the simplicity of the specimen preparation and the consistency of the results of the IDEAL-CT test make it a more desirable option.
Details
- Title: Subtitle
- Laboratory evaluation of hot and warm mixtures with high reclaimed asphalt pavement contents
- Creators
- Cody Hall
- Contributors
- Hosin “David” Lee (Advisor)Paul Hanley (Committee Member)Salam Rahmatalla (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Civil and Environmental Engineering
- Date degree season
- Spring 2025
- DOI
- 10.25820/etd.007837
- Publisher
- University of Iowa
- Number of pages
- xii, 105 pages
- Copyright
- Copyright 2025 Cody Hall
- Language
- English
- Date submitted
- 04/25/2025
- Description illustrations
- illustrations, tables, graphs
- Description bibliographic
- Includes bibliographical references (pages 59-61).
- Public Abstract (ETD)
- The purpose of this study was to find the best use for reclaimed asphalt pavement (RAP) materials in new roadway pavement construction while also determining the best way to go about testing these pavements. Asphalt pavement mixes with 0%, 20%, 30%, 40%, and 50% RAP contents were created and tested using three tests: one to test for pavement rutting and two to test for pavement cracking. The results indicated that as RAP content is increased, the resistance against rutting improved while the resistance against pavement cracking declined. Various pavement additives were included alongside the RAP materials and helped improve the mix’s performance, but did not achieve the performance of those mixes without RAP. At a RAP content of around 40%, results tended to peak for rutting and reach their lowest point for cracking. In testing the specimens, the Illinois Flexibility Index Test (I-FIT) and the Indirect Tensile Asphalt Cracking Test (IDEAL-CT) were compared. While requiring more material usage, the IDEAL-CT test has a simpler procedure and yields more consistent data than that of the I-FIT test, making the IDEAL-CT test the more desirable option. By making our processes more efficient and finding a way to recycle and reuse our aging infrastructure, the construction industry can lead the way to a more sustainable future.
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9984831123902771
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