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Evaluating the Low Temperature Behavior of Master Curves of Modified Binder and Investigating the a Parameter in Las Test

Abdollahi, Farhad | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53044 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tabatabaee, Nader
  7. Abstract:
  8. Master curves describe the behavior of asphalt binders over a wide range of temperatures and loading frequencies which are utilized by various predictive models in design and analysis procedure of asphalt mixtures. Frequency sweep test is extensively used for construction of master curves within the temperature range of 4 ̊C to 82◦̊C and frequency range of 0.01 to 30 Hz. There is a concern that master curves are unable to accurately represent the low temperature (below 4 C) behavior of binders. In this study a new cyclic loading pattern for the bending beam rheometer (BBR) test was utilized to conduct the low temperature tests and generate an isotherm compliance curve for incorporating the measured low temperature behavior into the master curve construction process. A novel method of fitting different behavioral models to the master curves was also introduced to improve the descriptiveness of the fitted model at low temperature zone. Moreover, this study evaluated different methods of calculating damage evolution rate (α) in Linear Amplitude Sweep (LAS) test. The results showed that incorporation of the BBR test results into the construction of master curve using the viscoelastic based method is the most accurate method in comparison with the other proposed methods. Also, the proposed method of this study regarding the fitting procedure of behavioral model to the asphalt binder master curve was found to improve the descriptiveness of the fitted model at low temperature region. Finally, it is recommended to calculate the damage evolution rate using the relaxation-master-curve based methods instead of the storage-moduli based ones
  9. Keywords:
  10. Master Curve ; Damage Evolution ; Modified Bitumen ; Bending Beam Rheometer ; Linear Amplitude Sweep ; Crack Propagation ; Generalized Kelvin Model (GKM)

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