Date of Award

12-2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Civil Engineering

First Advisor

Paul J. Cosentino

Second Advisor

Albert M. Bleakley

Third Advisor

Ralph Locurcio

Fourth Advisor

Luis Daniel Otero

Abstract

In this research, the behavior of Limerock (LR) aggregates blended with different reclaimed asphalt pavement (RAP) materials were investigated as an unbound base layer. Various combinations of LR and RAP, including 100%LR, 25%RAP75%LR, 50%RAP50%LR, and 100%RAP, were evaluated. Three main experiments performed on the samples were: static creep, static triaxial test, and cyclic triaxial test. The cyclic triaxial test was performed to measure the resilient modulus (MR) of materials. The results of the static triaxial test for 100% RAP showed that the deviator stress at failure steadily increased by increasing the confining pressure, while the 100% LR showed a maximum failure deviator stress at a pressure of 5 psi. Comparing the results of static creep and cyclic triaxial tests, despite higher creep tendency and higher cumulative plastic strains, the 100%RAP specimens showed higher MR values at different stress ratios (i.e., the ratio of deviator stress in the dynamic test to the failure deviator stress obtained from the static triaxial test) than other combinations containing LR. The MR of 100% LR specimens showed low sensitivity to stress ratio, whereas bulk stress had a significant effect on the MR of all test sample combinations. Finally, Numerical creep was compared against measurement. Static creep testing was completed at pressures of 18 and 25 psi. A combined time hardening model was used for Finite Element Model (FEM) simulation. Comparisons between the predicted creep and experimental creep produced an acceptable agreement. The parameter C1 in the combined time hardening model has a strong relationship with the creep deformation magnitude of the blends. Numerical and experimental analyses demonstrate a nonlinear relation between the strain and the percentage of RAP in the blends. The creep of 75%𝐿𝑅/25%𝑅𝐴𝑃 and 100%𝐿𝑅 samples are almost the same in both measurement and simulation.

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