Mechanistic Evaluation of Rubblized PCC Pavements

This report presents a mechanistic approach and procedures for determining layer coefficients to characterize the in-situ behaviors of rubblized pavements. This procedure was developed based on the 1993 AASHTO Pavement Design Guide utilizing Falling Weight Deflectometer (FWD) testing and in-place simulation using back-calculation layer modulus. In order to evaluate the rubblized pavement systematically, twelve constructed pavement sections were extensively tested by FWD annually after construction. The FWD data was processed using the proposed mechanistic procedure. In addition, statistical analysis was conducted to compare the pavement structure parameters each year, including layer coefficient and in-situ resilient modulus using Analysis of Variance (ANOVA) and Z-tests. In the ANOVA, the comparison of the structure capacities derived from the field FWD tests with those from the mechanistic procedure supports the null hypothesis, which concluded there is no difference between the structural numbers from these two methods. Also, statistically, the layer coefficients in each year are significantly different. The in-situ resilient moduli for each year varied significantly. The results from Z-test show that for Hot Mixed Asphalt (HMA) layers, the layer coefficient confidence interval could be as high as 0.70 and also as low as 0.38. For the base layers, the layer coefficient confidence interval could be as high as 0.25 and also as low as 0.16. A layer coefficient of 0.42 is recommended for HMA and 0.22 for rubblized layer for the design of HMA overlay on rubblized PCC pavement