Civil Engineering ETDs

Publication Date

7-3-2012

Abstract

It is believed that Hot Mix Asphalt (HMA) mixtures used in long-lasting pavements contain a threshold of strain value below which no fatigue damage occurs. This concept is known as the fatigue endurance limit (FEL). Although previous studies have shown that an endurance limit does exist for HMA mixtures, an established value is yet to be determined, with values varying from 70-400 microstrain (με) based on mixture variability. Traditional FEL vii identification is based on the phenomenological approach, which relates the number of loading cycles to fatigue failure with applied tensile strain and initial stiffness of material. This study determined the FEL of two HMA mixtures, SP-II (coarse mix) and SP-III (fine mix), using the phenomenological approach as well as a fundamental energy based approach, the dissipated energy concept. Results show that the dissipated energy approach estimates higher FEL values for both mix types than those estimated using the phenomenological approach. The FEL values for the SP-II and SP-III mixtures are estimated to be approximately 200 and 300 με respectively. Furthermore, laboratory fatigue failure criterion is defined as the number of loading cycles at which the stiffness of a material reduces by 50%. This study evaluated stiffness-based failure criteria for laboratory fatigue testing using the viscoelastic continuum damage mechanics (VCDM) approach. Results show that fatigue failure criterion of the VCDM approach correlates well with the stiffness-based fatigue failure criterion. In addition, the effect of polymer-modified binder on the FEL of HMA materials is investigated. The addition of modified binder to the SP-II mixture reduced the estimated FEL by 27%. On the other hand, the addition of modified binder to the SP-III mixture improved its estimated FEL value by 30%.

Keywords

Pavements, Asphalt concrete--Fatigue, Asphalt concrete--Fatigue.

Sponsors

New Mexico Department of Transportation

Document Type

Dissertation

Language

English

Degree Name

Civil Engineering

Level of Degree

Doctoral

Department Name

Civil Engineering

First Committee Member (Chair)

Stormont, John

Second Committee Member

Maji, Arup

Third Committee Member

Ng, Percy

Fourth Committee Member

Shen, Yu-Lin

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