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Title:A new asphalt binder parameter to predict asphalt concrete fatigue behavior
Author(s):Garcia Mainieri, Javier Jesus
Advisor(s):Al-Qadi, Imad L.
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Linear Amplitude Sweep
Delta G
Vegetable oil
Delta Tc
Black angle
Abstract:Fatigue cracking, caused by repeated heavy-traffic loading, is a source of critical distress in asphalt concrete (AC) pavements. It is well documented that asphalt binder impacts AC fatigue behavior. In recent years, the increasing use of recycled asphalt pavement (RAP) materials has significantly increased the use of relatively softer asphalt binders to balance the stiff aged binders used in RAP. In addition, various modifiers and additives are currently marketed to adjust the binder grade and enhance its performance at high and low temperatures by altering its rheological and chemical characteristics. The objective of this study was to explore the fatigue damage characteristics of modified asphalt binders. To achieve this objective, a variety of modified and unmodified binders at various aging conditions were tested. The limitations of using Superpave’s |G*|sin(δ), a small-strain testing parameter, to assess intermediate-temperature fatigue cracking susceptibility of asphalt binders have been well reported. It is possible that using a more realistic large-strain amplitude might help to better define the role of the asphalt binder. Hence, the linear amplitude sweep (LAS) test was used to characterize the damage tolerance of asphalt binders. However, existing data interpretation methods for LAS measurements (including AASHTO T391-20 and approaches reported in the literature) have shown inconsistent results among the modified binders. An alternative method for interpreting LAS results was developed in this study. The method considers test data until peak shear stress is reached. Complex stress states and failure patterns were observed in the specimens at this point. The parameter (Δ|G*|peak τ) was introduced to describe the reduction in complex shear modulus measured until the peak shear. The proposed parameter is able to capture the effect of aging and modification and can be determined using a more practical approach. Small- and large-strain testing parameters for unmodified and modified asphalt binders at various aging conditions were determined and studied. Intermediate-temperature small-strain behavior of binders could be predicted using low-temperature small-strain parameters and vice versa. A current trend is to enforce unique thresholds to parameters used for binder discrimination. This, however, may not be valid for stiffness-dependent parameters. Small-strain testing parameters and Δ|G*|peak τ characterize different engineering properties of asphalt binders. A new and practical asphalt binder parameter to characterize asphalt binder fatigue performance and control AC fatigue cracking.
Issue Date:2020-12-10
Rights Information:Copyright 2020 Javier Jesús García Mainieri
Date Available in IDEALS:2021-03-05
Date Deposited:2020-12

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