CHAPTER 1
INTRODUCTION
A Brief Introduction to Dynamic Modulus (IE*|)
Dynamic Modulus1 (IE*|) has been known to some researchers since the 1960s. But
the use of |E*| by departments of transportation has not been widespread. However,
current efforts in pavement research (revising the AASHTO Guide to the Design of
Pavement Structures and modeling for SuperPaveTM) rely on the use of |E*|. The 2002
revision of the AASHTO Guide to the Design of Pavement Structures uses the dynamic
modulus test (IE*|) to characterize mixes used on interstate highways and most other
high-volume highways that require superior load resistance. The guide is based on
mechanistic principle and requires a modulus to compute stresses and strains in hot-mix
asphalt (HMA) pavements.
Briefly, |E*| is the absolute value of the modulus of a viscoelastic material. The
dynamic (complex) modulus of a viscoelastic test is a response developed under
sinusoidal loading conditions. It is a true complex number as it contains both a real and
an imaginary component of the modulus and is normally identified by |E*| (or G*).A
Brief Introduction to Gradation and Packing
1 In viscoelastic theory, the absolute value of the complex modulus |E*|, by definition, is
the Dynamic Modulus. In the general literature, however, the term, "Dynamic Modulus"
is often used to denote any type of modulus that has been determined under "non-static"
load conditions.