Determination of remaining flexible pavement life. Volume 4: Analysis of in-situ granular layer modulus from dynamic road rater deflections

The ability of elastic layered theory coupled with nonlinear dynamic modulus tests to predict comparable pavement deflections to that measured from dynamic road rater deflections was investigated. It was found, for over 180 test dates, pavement sections, sensor combinations, that the theoretically predicted deflection over-estimated the measured road rater deflections by a factor of about 2 to 4 (2.8 average). It was concluded that the current laboratory method of modulus characterization to incorporate nonlinear behavior underestimates the modulus of that granular material. These results indicated that relationships between surface deflection, shear strain, and granular layer modulus can be applied to predict in-situ modulus from deflection measurements.