IMPROVED ASPHALT CONCRETE MIXTURE DESIGN PROCEDURE. FINAL REPORT

An extension to the current Texas mixture design procedure was evaluated. The extended mixture design/analysis procedures address: 1) the potential of hot mix asphalt concrete (HMAC) mixture to permanently deform, 2) flexural fatigue cracking potential, 3) subgrade protection, and 4) thermal cracking potential. The methodology is presented in an "easy-to-use" tabular and design chart format which can be incorporated into a mixture design/analysis sequence. The tests used to characterize mixture material properties are relatively simple and do not necessarily require sophisticated testing equipment. The properties required by the extended procedure include: compressive creep compliance, diametral resilient modulus and indirect tensile strength. The criteria by which the material properties are evaluated are based on the climatic region within which the pavement using the HMAC exists or will be placed and the category of the pavement structure. The compressive creep test proved to be a sensitive indicator of deformation potential. The creep test is used in the extended procedure as part of a new analysis procedure which accounts for viscoelastic nonlinearity of the asphalt concrete mixture as well as temperature sensitivity.