Cemented paste backfill(CPB)is one of the effective methods for resource utilization of tailings,but the high cost of ordinary Port-land cement(OPC)limits its utilization.Considering the poor performance of Na2CO3-activated binders,in this work,supplementary materials,including CaO,MgO,and calcined layered double hydroxide(CLDH),were used to modify their properties with the aim of finding an alternat-ive binder to OPC.Isothermal calorimetry,X-ray diffraction,and thermogravimetric analyses were conducted to explore the reaction kinetics and phase assembles of the binder.The properties of the CPB samples,such as flowability,strength development,and heavy metal immobiliz-ation effects,were then investigated.The results show that the coupling utilization of MgO and CLDH showed good performance.The strength of the Mg2-CLDH3 sample was approximately 2.94 MPa after curing for 56 d,which was higher than that of the OPC-based sample.Moreover,the cost of the modified Na2CO3-activated binder was lower than that of the OPC-based binder.Modified sample showed satisfactory heavy metal immobilization effects.These findings demonstrate that carbonate-activated binder modified by supplementary materials can be suitable in CPB.