Meso-scale adhesive/cohesive failure behaviors of porous asphalt mixtures considering random inhomogeneous distribution of binder

Abstract

Durability failure is the main concern of porous asphalt mixtures (PAC) and is caused by adhesive failure on aggregate-binder interface or cohesive failure within the binder. Adhesive/cohesive failure behaviors of PAC are dependent on the adhesive/cohesive properties of binder, which are influenced by the thickness and composition of binder. The aim of this study is to develop a meso-scale finite element modeling (M−FEM) considering the random inhomogeneous distribution of binder to investigate the meso-scale adhesive/cohesive failure behaviors of PAC. In the M−FEM, two types binder (mastic and mortar) with different thickness were reconstructed. The adhesive/cohesive properties of mastic and mortar with different thickness were evaluated by a modified pull-off test and used to determine the model parameters. A zero-thickness cohesive element was embedded into the interface between aggregate-binder and within binder, and the cohesive element parameters were determined and assigned based on the binder thickness. M−FEM with and without considering the random inhomogeneous distribution of binder (Model B and Model A) were constructed. The adhesive/cohesive strength of mastic increased with the thickness and reached a peak value at the thickness of 0.8 mm. The adhesive/cohesive strength of mortar increased with the thickness. The initial cracking point of Model A and Model B are different. In the cracking extension stage, adhesive failure was found in Model A, while both adhesive and cohesive failure behaviors were found in Model B. The random inhomogeneous distribution of binder has a significant impact on the damage initiation, stress distribution, stress transfer, and evolution of adhesive/cohesive failure behaviors of PAC. M−FEM considering the random inhomogeneous distribution of binder is more reasonable in the simulation of adhesive/cohesive failure behaviors. Increasing the binder thickness may have a contribution to the improvement of durability of PAC.