Investigation of factors affecting use of the poker chip test for asphalt binder and mixture performance

Vyas, Abhilash

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https://hdl.handle.net/2142/120558 Copy

Description

Title

Investigation of factors affecting use of the poker chip test for asphalt binder and mixture performance

Author(s)

Vyas, Abhilash

Issue Date

2023-05-02

Director of Research (if dissertation) or Advisor (if thesis)

Hajj, Ramez M.

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Asphalt
• Poker chip test
• Modified asphalt binders
• I-FIT
• MSCR

Abstract

With the surge in the use of modified asphalt binders throughout the world, it is important to examine the binders for performance outside of the linear viscoelastic (LVE) range. Modified asphalt binders, which are usually costlier, are expected to increase the service life of asphalt pavements. The first research problem in this thesis deals with the development of a framework for investigating the non-LVE and failure behavior of asphalt binders. Two approaches were utilized to evaluate the failure performance of eight binders including six novel modified asphalt binders. First, the poker chip test for cracking performance evaluation was conducted at different loading rates and aging levels. The results conclude the efficacy of the poker chip test to differentiate and rank the best-performing modified asphalt binders. Furthermore, the impact of varying the loading rates, aging levels, modifications, and performance grades was also studied. These results indicated that loading rates ranging from 1 to 4 N/sec can be used to differentiate modified binder performance with similar ranking, which allows a wider range of machines to be used to perform this test. In addition, the impacts of aging were studied to introduce differentiation between modifiers which are sensitive to aging. Apart from this, the Multiple Stress and Creep Recovery (MSCR) test was conducted to evaluate the rutting performance. MSCR results further augmented the confidence in initial rankings as polymer-modified binders showed superior performance to other modifier types. It was observed that the top two binders in terms of poker chip results also had the best MSCR performance. Hence, instead of balancing the performance, like is done for mixtures, between rutting and cracking performance, an optimum binder can be synthesized which has excellent performance against load-related cracking and permanent deformation. This sets the stage for a balanced binder selection and design process to be implemented into future specifications and research efforts. Furthermore, validation of the efficacy of the poker chip test in Asphalt Concrete (AC) mixture testing has been carried out. A set of unmodified and SBS-modified asphalt binders were used to perform the poker chip test based on the previously established framework. The Illinois Flexibility Index Test (I-FIT) Flexibility Index (FI) was used to assess the cracking resistance of Asphalt Concrete (AC) mixes. Fourteen laboratory-produced dense-graded AC mixtures using the same set of binders were compacted to investigate the relationship between the poker chip test results of asphalt binder and the flexibility of short and long-term aged AC mixtures obtained from the I-FIT. Two different aggregate sources, containing recycled materials, were utilized to prepare the mixes. The binders were distinguished based on modification and aging by the poker chip ductility parameter, further supporting the findings from the previous part of this study. Polymer-modified binders exhibited superior performance at all aging levels, indicating the positive impact of polymer addition on asphalt binders. Unlike the poker chip ductility parameter, the I-FIT FI values did not show any distinction based on binder modification. However, the test was sensitive to the amount of recycled material in the mix. The addition of Recycled Asphalt Shingles (RAS) to AC mixes prepared from Source 1 had an adverse effect on the FI values. Moreover, the effect of aging was observed, resulting in a reduction in FI value. It was observed that no linear relationship exists between the I-FIT and the poker chip test parameters, and both tests serve their individual purposes. These tests can be considered potential screening tools due to the ability of the poker chip test to distinguish asphalt binders based on modification and the ability of I-FIT to capture stiff AC mixes.

Graduation Semester

2023-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2023 Abhilash Vyas

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