ABSTRACT
Asphalt Concrete (AC) modulus is a critical component of mechanistic-empirical pavement design. It is well known that AC is a time and temperature dependent material that is influenced by vehicle speed and pavement temperatures in the field. However, current methods to characterize AC modulus, such as dynamic modulus (|E*|) and backcalculation from deflection basins resulting from falling weight deflect to meter testing (FWD) do not accurately represent field conditions. As a result, the backcalculated AC moduli from FWD testing do not accurately reflect the effect of vehicle speed on modulus. One means to circumvent the limitations of |E*| and FWD backcalculated AC moduli is to use measured strain values to backcalculate AC moduli. In this investigation, relationships between predicted tensile strain and AC modulus that enabled the application of measured strain at the bottom of the AC layer were determined to estimate in-place AC modulus. The estimated AC moduli values produced predicted tensile strains that closely matched measured strain values and were found to be an improvement over strain predicted from FWD backcalculated AC moduli.
