A process for curing a precast object, comprising: introducing the precast object into an envelope that is capable of containing a gas, wherein the envelope is sealed or vented, and wherein the precast object is made of a carbonatable calcium silicate-based cement and the gas is carbon dioxide; providing a primary gas circulation loop, comprising: introducing a gas at a first condition into the envelope, flowing the gas over a surface of the precast object inside the envelope to bring the gas to a second condition, wherein gas in the second condition has a lower temperature, higher relative humidity and reduced flow rate, relative to the first condition, passing the gas at the second condition through a primary gas conditioning system to restore the gas to its first condition, and recirculating the gas into the primary gas circulation loop; providing one or more secondary gas circulation loop, wherein the secondary gas circulation loop comprises: taking the gas in the envelope at a third condition, wherein gas in the third condition has a lower temperature, higher relative humidity and reduced flow rate, relative to the first condition, passing it through a secondary gas conditioning system to condition it to a fourth condition, wherein gas in the fourth condition has a higher temperature, lower relative humidity and an increased flow rate, relative to the third condition, and flowing the gas after conditioning to the fourth condition over at least another surface of the precast object; and curing the precast object for a time sufficient to produce a cured precast object. introducing the precast object into an envelope that is capable of containing a gas, wherein the envelope is sealed or vented, and wherein the precast object is made of a carbonatable calcium silicate-based cement and the gas is carbon dioxide; providing a primary gas circulation loop, comprising: introducing a gas at a first condition into the envelope, flowing the gas over a surface of the precast object inside the envelope to bring the gas to a second condition, wherein gas in the second condition has a lower temperature, higher relative humidity and reduced flow rate, relative to the first condition, introducing a gas at a first condition into the envelope, flowing the gas over a surface of the precast object inside the envelope to bring the gas to a second condition, wherein gas in the second condition has a lower temperature, higher relative humidity and reduced flow rate, relative to the first condition, passing the gas at the second condition through a primary gas conditioning system to restore the gas to its first condition, and recirculating the gas into the primary gas circulation loop; providing one or more secondary gas circulation loop, wherein the secondary gas circulation loop comprises: taking the gas in the envelope at a third condition, wherein gas in the third condition has a lower temperature, higher relative humidity and reduced flow rate, relative to the first condition, passing it through a secondary gas conditioning system to condition it to a fourth condition, wherein gas in the fourth condition has a higher temperature, lower relative humidity and an increased flow rate, relative to the third condition, and flowing the gas after conditioning to the fourth condition over at least another surface of the precast object; and taking the gas in the envelope at a third condition, wherein gas in the third condition has a lower temperature, higher relative humidity and reduced flow rate, relative to the first condition, passing it through a secondary gas conditioning system to condition it to a fourth condition, wherein gas in the fourth condition has a higher temperature, lower relative humidity and an increased flow rate, relative to the third condition, and flowing the gas after conditioning to the fourth condition over at least another surface of the precast object; and curing the precast object for a time sufficient to produce a cured precast object.