ISSN: 0090-3973
Published Online: 10 November 2006
Page Count: 9

Laboratory-based Unified Permanent Deformation Model for Hot-Mix Asphalt Mixtures

Hajj, Elie Y.
Ph.D., Professor, and Professor and Director,Pavements/Materials Program, Department of Civil Engineering, University of Nevada,NV,

Siddharthan, Raj V.
Ph.D., Professor, and Professor and Director,Pavements/Materials Program, Department of Civil Engineering, University of Nevada,NV,

Sebaaly, Peter E.
Ph.D., Professor, and Professor and Director,Pavements/Materials Program, Department of Civil Engineering, University of Nevada,NV,

Weitzel, Dean
Chief Materials Engineer,Materials Division, Nevada Department of Transportation,NV,

(Received 30 November 2004; accepted 18 October 2006)

Abstract

Conventionally, the resistance of hot-mixed asphalt (HMA) mixtures to permanent deformation is measured by repeated load triaxial (RLT) or repeated shear at constant height (RSCH) testing. The data from these tests have been treated as independent datasets in the prediction of rutting potential in HMA layers. This paper presents a unified permanent deformation model using response measurements made from both tests. The new model quantifies the accumulated permanent shear strain as a function of number of load cycles and factor of safety (FOS). The factor of safety is defined in the q-p space and is evaluated based on the applied stresses and triaxial compression strength properties (cohesion and angle of internal friction). For the specific mixture used in this study, a good correlation was found between the cumulative permanent shear strain and the FOS level, irrespective of the stress conditions and the type of test used.

Keywords:
permanent shear strain, Drucker-Prager failure envelope, factor of safety, unified model, triaxial strength test, repeated load triaxial, repeated shear constant height

Paper ID: JTE13153
DOI: 10.1520/JTE13153
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