Dynamc Modulus Performance Of Idot Mixtures

Abstract

The dynamic modulus (E*) of hot mix asphalt (HMA) is the currently preferred structural characterization test for use in structural design. This value has been selected for inclusion in the Mechanistic Empirical Pavement Design Guide (MEPDG). With the introduction of Superpave mix designs, the structural properties of mixtures have changed in recent years, and an examination of current stiffness values is required as the Extended Life Hot Mix Asphalt Pavement (ELHMAP) design concepts require stiffness for several different HMA layers in the structure. The use of pre-Superpave modulus values could be inappropriate. Twenty mixtures representing surface and binder mixtures were sampled from the field. These mixtures were selected to cover the spectrum of mixtures and binders and mix designs being used throughout the state. Gyratory samples were compacted to 7 and 4 percent air voids and then prepared for E* testing. Three replicate samples were prepared for each mixture. Testing was conducted at three temperatures (-4 o, 10 o, and 20o C) and frequencies from 0.01 to 10 Hz. Five additional mixtures were added to the testing program. These mixtures were used to construct the ELHMAP sections to be used for response and fatigue testing under full scale loading. The E* data shows that current IDOT mixtures have excellent modulus values which may be higher than the previously used values.