Mechanistic Empirical Pavement Design Guide Input Parameters for Unbound Aggregates in Oklahoma

This study analyzed resilient modulus (Mr) and other routine properties [gradation, LA Abrasion loss, standard Proctor, and unconfined compressive strength (UCS)] of commonly used limestone and sandstone aggregates in Oklahoma. A total of four stress-based regression models were evaluated using a statistical software package ("SPSS", Version 17), and material constants (k1, k2, and k3) for these aggregates were determined. The octahedral model was found to outperform the other models and is recommended for use in Level 1 analysis. Correlation equations for material constants, required for Level 2, were developed using routine aggregate properties, and the universal model was found to be the "best fit" model with a R2 value of 0.57. The estimated Mr values obtained from different models were in agreement with each other, and the variations of Mr values were within 4%. However, all of these models would result in conservative designs compared to the Mechanistic Empirical Pavement Design Guide (MEPDG) recommended typical values. The findings of this study are expected to be helpful in the implementation of the MEPDG in Oklahoma and elsewhere.