The assessment of the structural adequacy of an existing pavement scheduled for rehabilitation is an important aspect of pavement rehabilitation design. Non-destructive testing (NDT) has been widely used to determine the design inputs for existing pavement layers in rehabilitation design. The Falling Weight Deflectometer (FWD) is used by different agencies for the non-destructive evaluation of existing pavement layers and subgrade properties. In addition, the deflection basin from the FWD can be applied to select an appropriate rehabilitation strategy. The backcalculated elastic properties of each layer in the pavement and the subgrade from the FWD testing are required for Level 1 and 2 inputs in rehabilitation design when using the AASHTOWare Pavement ME Design program.
This paper focuses on the backcalculation of pavement layers and subgrade modulii using various methods. The backcalculated resilient modulii (MR) of the base and subgrade from these procedures are compared with modulii from the forward calculation method. This forward calculation method was developed under the Federal Highway Administration’s project for reviewing Long-Term Pavement Performance (LTPP) backcalculation data. The calculated modulii are also compared to the laboratory determined resilient modulus for similar materials. The highway sections used in the study are the same test sections proposed to be used to calibrate the Pavement ME distress models in Manitoba. The selected modulii of the pavement layers and subgrade will be used as inputs in the calibration process.
