Force　chains　provide　the　mesoscopic　framework　to　elucidate　asphalt　mixture＇s　load-induced　deformation　mechanisms,　yet　their　stability　under　loading　conditions　remains　unquantified.　This　study　introduces　the　force　chain　toughness　to　investigate　the　evolution　mechanisms　of　force　chains　with　different　gradation　designs.　The　force　chain　survival　rate　was　proposed　to　quantify　the　force　chain　toughness　and　verified　by　the　reloading　test.　The　results　demonstrate　that　the　force　chain　survival　rate　serves　as　an　effective　indicator　of　the　force　chain　toughness　in　asphalt　mixtures,　as　confirmed　by　its　inverse　correlation　with　aggregate　vertical　displacement.　The　force　chain　toughness　is　determined　by　the　competing　effect　between　the　nominal　maximum　aggregate　size　and　the　distinction　of　aggregate　size,　resulting　in　it　not　increasing　monotonically　with　the　nominal　maximum　aggregate　size　of　the　asphalt　mixture.　The　negative　correlation　between　the　force　chain　survival　rate　and　key　aggregate　size　passing　rate　is　attributed　to　the　excessive　filling　and　interference　effects　of　small　aggregates.　Dominant　strong　force　chains’　mesoscopic　spatial　features,　including　the　geometric　linearity　and　inclination　angle　relative　to　the　loading　direction,　predominantly　govern　the　force　chain　toughness　of　asphalt　mixtures,　instead　of　the　number　of　dominant　strong　force　chains.　The　alignment　between　virtual　simulations　and　laboratory　test　results　underscores　the　applicability　of　the　proposed　mesoscopic　framework　for　performance-based　asphalt　mixture　design,　thereby　providing　guidance　for　the　design　of　aggregate　gradation　in　actual　asphalt　pavements.　©　2025　Elsevier　Ltd