Permanent deformation behavior of unbound granular materials and rutting model development

Chow, Liang Chern

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https://hdl.handle.net/2142/50674 Copy

Description

Title

Permanent deformation behavior of unbound granular materials and rutting model development

Author(s)

Chow, Liang Chern

Issue Date

2014-09-16

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

Tutumluer, Erol

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)

• Unbound granular material
• Permanent deformation
• Rutting
• Shear strength
• Shear Stress Ratio
• Repeated load triaxial testing
• Mechanistic-Empirical Pavement Design Guide (MEPDG)
• Rutting model

Abstract

The rutting damage model as incorporated into the AASHTO’s mechanistic-empirical (M-E) pavement design approaches (i.e. Pavement ME Design) was found to produce inadequate rut estimates in unbound aggregate base/subbase layers by discounting the contribution of stress state from the original Tseng and Lytton (1989) model. This research study was aimed at developing a new permanent deformation prediction model that would properly take into account the effects of applied load, applied stress in relation to material’s strength and number of load cycles through a well-established laboratory test matrix for mechanical properties. Sixteen (16) different unbound granular materials commonly used in the state of North Carolina (NC) for pavement subbase/base applications were used in this study. The goal was to accurately estimate the field performances of aggregate base courses through development of a new rutting damage model, referred to as UIUC rutting model. The laboratory phase of this study presented in this thesis considered a target engineered gradation within the lower and upper limits of North Carolina Department of Transportation (NCDOT) base course specification bands with established moisture-density relationship for each of the selected granular materials. Experimental characterizations primarily consisted of imaging based aggregate shape analyses, moisture-density, resilient modulus, shear strength, and permanent deformation tests based on a comprehensive test matrix. The concept of Shear Stress Ratio (SSR) or stress/strength level, which can be derived from Mohr-Coulomb failure criteria, was introduced in this study to properly examine the effects of varying degree of stress/strength to permanent deformation behavior of unbound materials. These test results established a complete database to develop the UIUC rutting model in order to properly capture the effects of stress state and material properties. The model predictions were compared with Pavement ME Design results to justify the validity and performance of the proposed model.

Graduation Semester

2014-08

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http://hdl.handle.net/2142/50674

Copyright and License Information

Copyright 2014 Liang Chern Chow

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