Use of FWD Data for Pavement Material Characterization and Performance

Abstract

Conventionally used FWD backcalculation and pavement stress-strain computation procedures are based on linear static layered elastic theory. This paper presents a simple hypothetical case study in which the applicability of the assumptions made in the foregoing procedures is investigated using the finite-element method. The pavement displacements computed using static/dynamic falling-weight deflectometer (FWD) loading and constant and stress-dependent material properties were used as input for the backcalculation analysis. The assumed and backcalculated layer moduli were compared. The backcalculated asphalt concrete (AC) moduli values were within acceptable limits for all pavement sections studied except for the case of the thin AC pavement with a shallow rigid base. The subgrade moduli were consistently underpredicted; the base course moduli were both underpredicted and overpredicted. Widely used traffic-induced pavement strains that are related to pavement performance that were obtained under different loading and material property characterizations were also compared. Results indicate that the conventional procedures are not conservative, especially for thick AC pavement sections.