The　deterioration　mechanism　of　concrete　materials　with　expanding　serpentine　aggregates　subjected　to　fast　neutron　radiation　(MeV＞1.0)　was　investigated　by　numerical　simulation.　Considering　the　combined　effects　of　temperature　and　aggregate　radiation-induced　volumetric　expansion　(RIVE)　on　the　mechanical　behavior　and　the　residual　elasticity　of　concrete,　a　two-stage　numerical　model　was　established　at　the　mesoscopic　scale.　The　residual　elasticity　of　concrete　was　investigated　numerically　and　validated　by　comparing　with　experimental　data.　Based　on　the　numerical　results,　the　analytical　formulas　of　concrete　swelling　and　the　residual　elasticities　were　proposed.　The　3D　numerical　approach　can　provide　an　effective　tool　for　assessing　the　combined　effect　of　temperature　and　RIVE　in　the　aggregates　on　the　mechanical　behavior　and　the　residual　elasticity　of　concrete　with　application　to　fast　neutron　radiation,　and　for　revealing　the　deterioration　mechanism　of　concrete　materials　with　expanding　aggregates.　The　proposed　model　serves　as　a　first　attempt　and　provides　a　theoretical　benchmark　and　can　be　potentially　applied　for　the　life　extension　evaluation　of　aging　concrete　materials.　©　2025　Tsinghua　University.　All　rights　reserved.