Asphalt　concrete　(AC)　is　of　a　three-phase　system　comprising　of　coarse　aggregate,　FAM　(fine　aggregate　matrix)　and　interfacial　zones　(ITZ).　The　interfacial　zone　between　FAM　and　coarse　aggregate　plays　a　critical　role　which　determines　the　mechanical　performance.　This　paper　presents　a　numerical　simulation　of　the　mechanical　behavior　of　ITZ,　to　quantitatively　analyze　damage　of　AC　with　or　without　composite　additives.　The　results　indicated　that　damage　at　the　ITZ　was　initiated　from　the　top　area　followed　by　a　downward　propagation.　Both　cohesive　and　adhesive　damage　of　AC　with　composite　additives　were　less　serious　than　that　without　composite　additives,　and　the　damage　severity　was　greatly　affected　by　the　thickness　of　FAM　layer.　The　most　serious　damage　was　observed　for　the　thick　FAM　layer　under　a　rectangular　loading　pattern.　As　such,　the　adhesive　damage　area　and　cohesive　damage　area　of　AC　with　composite　additives　were　found　to　be　1.7%　and　33.8%　respectively,　less　than　that　without　composite　additives.　©　2018　Elsevier　Ltd