Methods of making sustainable ductile cast cementitious structure for carbon dioxide sequestration

A method of preparing a cementitious structure for carbon dioxide sequestration, the method comprising:

• conditioning a cementitious composite material comprising a binder and water by exposing the cementitious composite material to greater than or equal to about 50% relative humidity to less than or equal to about 80% relative humidity at a temperature of less than or equal to about 25° C. for a duration of greater than or equal to about 3 hours to less than or equal to about 4 hours, wherein the binder comprises a Type C fly ash and a Type F fly ash, wherein the Type C fly ash and the Type F fly ash are cumulatively present at greater than or equal to about 60% by weight of the cementitious composite material and the cementitious composite material is free of Portland cement;
• and
• drying the cementitious composite material to remove at least greater than or equal to about 20% by weight of initial water in the cementitious composite material to form the cementitious structure capable of a carbon dioxide (CO2) uptake level of greater than or equal to about 6% by weight binder, wherein the cementitious structure has a tensile strain capacity of greater than or equal to about 1% and a uniaxial tensile strength of greater than or equal to about 1 MPa.