REGRESSION MODELING OF RESILIENT MODULUS OF UNBOUND AGGREGATES

摘要

Resilient response of granular aggregate is a key input parameter in all three hierarchical levels of the new Mechanistic-Empirical pavement Design Guide (MEPDG), which requires a comprehensive evaluation of resilient modulus (M-r) database(s) for local conditions. To this end, M-r data and other routine properties (gradation, LA Abrasion loss, standard Proctor, and unconfined compressive strength (UCS)) of 105 samples of two different types of aggregate (limestone and sandstone) were analyzed in this study. A total of four stress-based regression models were evaluated using a statistical software package ("SPSS", Version 17), and material constants (k(1), k(2), and k(3)) 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 R-2 value of 0.57. Default (Level 3) M-r values for these aggregates were also estimated using the average material constants. The estimated M-r values obtained from different models were in agreement with each other, and the variations of M-r, values were within 4%. However, all of these models would result in conservative designs compared to the MEPDG recommended typical values. The findings of this study are expected to be helpful in the implementation of the MEPDG in Oklahoma and elsewhere.