Published Online: 23 August 2013
Page Count: 23
Tarefder, Rafiqul A.
Associate Professor, Dept. of Civil Engineering, Univ. of New Mexico, Albuquerque, NM
Faisal, Hasan M.
Graduate Research Assistant, Department of Civil Engineering, University of New Mexico, Albuquerque, New Mexico
(Received 13 January 2013; accepted 22 July 2013)
Researchers have used the Oliver-Pharr method to analyze nanoindentation test results for viscoelastic materials without considering the viscous effect. This study develops procedure to analyze nanoindentation creep results of asphalt binder considering the viscous effect. In particular, models such as Voigt, Burger, and others, which use spring, dashpot, and rigid body are used to fit the laboratory data. The spring-dashpot-rigid (SDR) element model uses the loading, holding, and unloading time-displacement data to predict the modulus, hardness, and indentation viscosity of the material. Modulus and hardness from the Oliver-Pharr model are much less than those from SDR model. In addition to modulus and hardness, the SDR model and other Voigt and Burger models can provide viscous parameters that are very important for the advanced modeling of asphalt concrete. In the study, the model parameter retardation time shows a clear decreasing trend with increase in loading rate, however, no clear trend is found between retardation time and dwell time (the time where maximum load is kept constant for a specific period of time). In the study, the nanoindentation test results are analyzed with both the nonlinear SDR model, as well as the linear SDR model. However, the nonlinear SDR model showed higher efficiency in prediction compared to the linear SDR model.
Paper ID: ACEM20130060