Evaluating　and　quantifying　the　impact　of　the　introduction　of　nanomaterials　on　microscopic　properties　is　crucial　to　ensure　the　carbonation　resistance　of　nano-modified　cementitious　materials.　In　this　paper,　Titanium　dioxide　@Layered　Double　Hydroxide　(TiO2@LDH)　nanospheres　with　core-shell　structure　were　synthesized　by　two-step　method　and　showed　notable　dispersion　and　stability　in　cementitious　matrix.　The　effect　of　TiO2@LDH　on　cement　hydration,　carbonation　behavior,　microstructure　and　mechanical　properties　of　mortar　were　investigated.　The　results　show　that　under　the　effect　of　nucleation　and　refinement,　the　hydration　degree　of　mortar　containing　TiO2@LDH　increases　by　19.6　%　and　the　total　porosity　decreases　by　12.5　%,　and　the　compressive　strength　increased　by　about　27.01　%.　By　adjusting　the　growth　rate　and　particle　size　of　CH　crystals,　the　CO2　absorption　capacity　of　mortar　increased　by　28　%.　The　synergistic　mechanism　of　TiO2@LDH　promoting　hydration　and　early　CO2　uptake　to　improve　the　carbonation　resistance　of　mortar　was　proposed.　More　importantly,　based　on　the　reduction　of　mortar　porosity　and　the　formation　of　early　physical　barriers,　the　carbonation　resistance　and　gas　permeability　of　mortar　were　reduced　by　53.7　%　and　79.7　%,　respectively.　This　novel　nano-control　technology　provides　a　promising　alternative　for　the　application　and　development　of　carbon　sequestration　in　cementitious　materials.　©　2025　Elsevier　Ltd