Abstract:
The thermal contraction performance of asphaltic pavement structure is affected by the
interaction between the bituminous layer and the granular layer underneath. The constraint
action of the graded gravel base layer plays an important role in affecting the temperature
strains in top asphalt layer. The focus of the present paper is to investigate the interactive
thermal contraction mechanisms between the asphalt and granular base layers from a
novel perspective. In this paper, a type of composite structure was proposed, and the
dynamic and static strain acquisition system (DSSAS) was adopted to conduct the indoor
thermal contraction tests. Combining the discrete properties of graded gravel materials
(UAM) and the continuous characteristic of asphalt mixtures, the Finite Difference Method
and Discrete Element Method (FDM-DEM) coupling models were established and
calibrated. And the linear elastic and elastoplastic models of graded gravel layer were
compared. Results show that the continuous-discrete coupling model has higher
consistency with the laboratory test than the continuum model, and the relative error of
thermal contraction coefficient is no more than 8.1%. The thermal strain-time curves of
asphalt mixture and its composited specimens exhibit a nonlinear change law of first fast
and then slow. And the asphalt mixture types and cooling temperature differences have
little effect on the constraint action of unbound aggregate layer. The coordinated
deformation between unbound aggregate base layer and asphalt mixture overlay can be
realized by particle contact recombination, the inwardly extruded movement, loose on both
ends and the middle compaction. Theoretical support for the research of low temperature
crack resistance of graded macadam base asphalt pavement can be found in this paper.
