To　investigate　the　mechanism　of　the　effect　of　calcium　oxide　and　sodium　carbonate　activated　slag　on　the　autogenous　shrinkage　of　alkali-activated　cement,　an　alkali-activated　slag　martar　(AM)　was　prepared　using　calcium　oxide　and　sodium　carbonate　(molar　ratio　of　1∶　1)　as　the　combined　activator.　The　effect　of　combined　activator　Na2O　equivalent　(i.　e.　the　by　weight　ratio　of　Na2　O　produced　by　the　reaction　of　the　combined　activators　to　slag,　i.　e.　2.　5%,　4.　5%,　6.　5%　and　8.　5%)　on　the　autogenous　shrinkage　of　AM　was　investigated.　The　hydration　products　and　microstructure　were　characterized　by　X-ray　diffraction,　thermogravimetric　analysis,　mercury　intrusion　porosimetry,　and　nuclear　magnetic　resonance.　The　results　indicate　that　with　the　increase　of　Na2O　equivalent,　the　increase　of　water　consumption　due　to　the　reaction　of　activators　and　pore　structure　refinement　leads　to　the　increase　of　pore　pressure,　and　the　amount　of　absorbed　Na　+　increases　due　to　the　increase　of　amount　of　Si4　+　in　C　-　(A)　-　S　-　H　replaced　by　Al3　+　,　resulting　in　the　increase　of　C　-　(A)　-　S　-　H　slippage.　The　increase　of　hydration　degree　induces　the　increase　of　the　amount　of　hydration　products,　resulting　in　the　increase　of　the　autogenous　shrinkage.　AM　with　Na2O　equivalent　of　6.　5%　is　the　best　group　with　its　mechanical　properties　higher　than　those　of　ordinary　Portland　cement　mortar　(OM),　but　its　autogenous　shrinkage　greater　than　that　of　OM　due　to　its　lower　crystal　content　and　denser　pore　structure.　©　2024　Harbin　Institute　of　Technology.　All　rights　reserved.