The resilient moduli (MR) of surface, base and subbase pavement layers and that of the roadbed soil are primary design input parameters to all pavement design software. The modulus values could be obtained from the laboratory using cyclic load tests or backcalculated from Falling Weigh Deflectometer (FWD) data (deflection data). In this study FWD data were used to backcalculate the modulus values of unbound granular materials supporting rigid and flexible pavements. The backcalculated MR values were then compared to those values obtained by Michigan Technological University (MTU) in the laboratory. The results show that on average the backcalculated MR values of the unbound granular layer are about four times higher than the laboratory determined MR. The pavement type and the aggregate characteristics, such as aggregate type and gradation, did not have any significant impact on the backcalculated MR values.
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