Page 143 - MODELING OF ASPHALT CONCRETE

CHAPTER 5

Complex Modulus from the

Indirect Tension Test

Y. Richard Kim, Youngguk Seo, and Mostafa Momen

Abstract
This chapter presents the results from an analytical/experimental study on the
dynamic modulus testing of hot mix asphalt (HMA) using the indirect tension (IDT)
mode. An analytical solution for the dynamic modulus in the IDT mode is developed
using the theory of linear viscoelasticity. To verify the analytical solution, temperature
and frequency sweep tests were conducted on 24 asphalt mixtures commonly used in
North Carolina, using both axial compression and IDT test methods. Graphical and
statistical comparisons of results from the axial compression and IDT test methods
show that the dynamic modulus mastercurves, phase angles, and shift factors derived
from the two methods are in good agreement.

Introduction
One of the issues related to the role of dynamic modulus in pavement management
is its use in forensic studies and pavement rehabilitation design. The current
dynamic modulus protocol, AASHTO TP-62, calls for the uniaxial compression
testing of 100-mm-diameter and 150-mm-tall asphalt concrete specimens. It is often
impossible to obtain this size specimen from actual pavements. Given that a typical
asphalt layer thickness is less than a few inches and that coring is the most
effective method of obtaining specimens from actual pavements, the indirect
tension (IDT) test of cores seems to be more appropriate for the evaluation of
existing pavements.
In this chapter, linear viscoelastic solutions are presented for the determination
∗
∗
of dynamic modulus (|E |) of asphalt concrete from the IDT test data. The IDT |E |
values are then compared with the values determined from the axial compression
complex modulus testing for 24 different asphalt mixtures typically used in North
Carolina.

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