Page 109 - MODELING OF ASPHALT CONCRETE

Overview of the Stif fness Characterization of Asphalt Concr ete 87

Conclusions
The stiffness of asphalt concrete is a material property that is central to the performance
of asphalt pavements. It depends upon many factors including stress state, temperature,
moisture, strain rate, and damage condition. Being able to measure it precisely and
accurately in the laboratory and the field is essential to making the design, construction,
and management of pavements possible in the present and in the future. Subsequent
chapters present methodologies and considerations for measuring the stiffness of
asphalt concrete. A large part of the need for making these measurements is the greatly
increased role that numerical predictions using mechanics models on computers will
have on all engineering and construction operations related to pavements. Mechanics
models require material properties of which asphalt concrete stiffness is one of the more
important. The composition of the asphalt concrete determines its stiffness in both its
damaged and undamaged conditions and also determines its response to the various
stresses that are imposed upon it under traffic. Tiny variations of critical components of
the mixture can have large scale effects on how the mix behaves under load and this is the
reason that construction quality control will become an increasingly critical factor in the
future. Defining in a mechanics sense how asphalt concrete stiffness is affected by all of
these factors is what makes it possible to identify the critical components and to incorporate
them in specifying the performance that those pavements will need to provide in order to
meet taxpayer, safety, and public policy expectations.

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