Page 236 - MODELING OF ASPHALT CONCRETE

214 Cha pte r Ei g h t

Disturbed State Concept
The DSC is based on the idea that the behavior of a deforming material (element) can be
expressed in terms of the behavior of the relative intact (RI) or continuum part and the
microcracked (or healed) part called the fully adjusted (FA) part. During the deformation,
the (initial) RI material transforms continuously into the FA part and at the limiting
condition (load), the entire material element approaches the FA state. Figure 8-4 shows a
schematic of the RI and FA states. The disturbance, which acts as the coupling and
interpolation mechanism, allows definition of the actual or observed behavior in terms
of those of the material in the RI and FA states.
The transformation of the material from the RI to the FA state occurs due to the
microstructural changes caused by relative motions such as translation, rotation, and
interpenetration of the particles and softening or healing at the microlevel. The
disturbance expresses such microstructural motions, and hence, it is not necessary to
define material response at the particle level, as is done in the micromechanical

FIGURE 8-4 Schematic representation of disturbed state concept.