کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4922044 | 1429561 | 2017 | 16 صفحه PDF | دانلود رایگان |
Dynamic modulus is a measure of stiffness of an asphalt concrete (AC) mix when subjected to cyclic sinusoidal compressive stresses. In the Mechanistic-Empirical Pavement Design Guide (MEPDG) and its software Pavement ME, dynamic modulus (Eâ) is an essential parameter for the prediction of asphalt pavement distresses such as rutting and fatigue cracking. Several empirical models have been developed to estimate the Eâ from AC mix properties to compliment laboratory measured Eâ values. Two models developed under NCHRP 1-37A and NCHRP 1-40D projects have been integrated into the MEPDG program. The models estimate Eâ values when Level 2 and Level 3 inputs for AC mixes are used. This paper presents the evaluation of uncalibrated Eâ values obtained from NCHRP 1-37A and NCHRP 1-40D and compares the results to two calibrated techniques; an exponential fit of uncalibrated model outputs, and updated model coefficients using nonlinear multiple regression. In total, 51 specimens from 17 types of AC mixes containing 0-50% RAP were prepared and tested in the laboratory. Eâ was determined in the laboratory and compared to estimated values based on calibrated and uncalibrated models. The results showed that uncalibrated NCHRP 1-37A produced lower error in predicting Eâ than uncalibrated NCHRP 1-40D. Both calibration techniques enhanced the accuracy of the models, however nonlinear multiple regression showed the best potential for predicting Eâ. Calibrated models showed improvement in prediction of Eâ for all RAP mixes for Level 3 inputs, although high RAP mixes showed the least improvement among the other RAP mixes.
Journal: International Journal of Pavement Research and Technology - Volume 10, Issue 3, May 2017, Pages 203-218