Construction of Dynamic Modulus Master Curves with Resilient Modulus and Creep Test Data

Abstract

For the past few decades, the stiffness of materials used for roadway design and construction has been commonly characterized by the resilient modulus, defined as the ratio of the applied stress to the recoverable strain. However, the resilient modulus is not a fundamental material property of a viscoelastic material. Therefore, the concept of resilient modulus has been subsequently diminished in the latest Mechanistic–Empirical Pavement Design Guide. Although that design guide could not endorse the use of the resilient modulus test protocol as the primary means of characterizing the asphalt concrete modulus in the design of flexible pavements, that protocol has been a primary mixture test, and much laboratory testing has been completed to date. Analysis methodologies are introduced for backcalculating the dynamic modulus from the resilient modulus test data. To assess the usefulness of the proposed algorithm, laboratory experiments in both the uniaxial compression and indirect tensile test modes were carried out on asphalt specimens compacted with the Superpave^® gyratory compactor. The backcalculated dynamic modulus was used to generate the master curve, and the creep test data were used to enhance the accuracy of the master curve. The advantage of such a methodology is that the existing resilient modulus and creep test data can be leveraged for estimating the dynamic modulus. The approach would significantly save time and effort in reevaluating the dynamic modulus of an asphalt mixture when the resilient modulus and creep test data are available.