The Use of Laboratory-Measured and Strain-Gauge Backcalculated Asphalt Stiffness for Rutting Performance Prediction

Abstract

Laboratory tests are conducted with asphalt concrete materials to determine the expected in-situ performance. In addition, laboratory test results are commonly used in mechanistic-empirical design methods for material characterization to improve the predictive accuracy of the models. However, the effectiveness of laboratory tests in characterizing the long-term performance of asphalt concrete materials needs to be validated to be able to use the results for pavement design and long-term performance prediction. Inaccurate performance characterization and prediction can directly affect the decision-making process for pavement maintenance, rehabilitation, and reconstruction and result in unexpected early failures in the field. The major objective of this study is to determine the impact of using laboratory-measured asphalt stiffness on the prediction accuracy of mechanistic-empirical models. In addition, the effect of using linear-elastic modeling assumptions (layered elastic theory) and neglecting the nonlinearity of pavement response at high load levels (and/or at high strain levels for weaker structures) on the predicted rutting performance was determined. In this study, the effectiveness of the use of laboratory asphalt stiffness tests for in-situ asphalt stiffness characterization was determined by comparing the rutting performance predicted using laboratory-measured stiffness to rutting predicted using strain-gauge backcalculated stiffness. It was determined that laboratory tests are able to characterize the in-situ stiffness characteristics of the asphalt mix used in this study and the stiffness characterization process suggested in this study can provide reliable rutting performance predictions. Results of this study are only applicable to tested rubberized asphalt concrete mixtures.