Structural Layer Coefficient for Flexible Pavement

Abstract

In order to design flexible pavements employing the AASHO Interim Guide, one must know the layer coefficients of pavement materials. The results of a study to derive structural layer coefficients of several Mississippi pavement materials—surface mixture and base mixture of asphalt concrete, soilcement, and soil‐lime—are presented. Fatigue cracking is the criterion employed in deriving the structural layer coefficients. A model is developed to estimate fatigue life or performance or both of pavements treating traffic, material characteristics, and environmental effects as stochastic variables. Material characteristics that govern the pavement performance include resilient modulus and fatigue sensitivity. Although the inputs are probabilistic, the resulting model equation is deterministic and amenable to direct solution for the analysis/design of flexible pavements. Using this model with the stipulation that fatigue cracking in the wheel paths be less than 45%, the researcher establishes equivalent pavement cross sections. The layer equivalency of various materials is derived by comparing equivalent cross sections. The resulting layer coefficient values for base, soil‐cement, and soil‐lime are in agreement with those proposed by the AASHO Committee on Design.