Enhanced carbonation and carbon sequestration in cementitious binders

1. A manufacturing process of a cement-based product, comprising:

(a) combining at least one cement component that includes portlandite (Ca(OH) 2 ) with aggregates;

(b) shaping the at least one cement component and the aggregates to form a monolithic structural element;

subsequent to the shaping in (b),

(c) disposing the monolithic structural element in a reactor;

(d) exposing the monolithic structural element in the reactor to gaseous CO 2 to form a cement-based product,

wherein the exposing in (d) includes converting portlandite to calcium carbonate, and

wherein a partial pressure (concentration) of the CO 2 present in the reactor is higher than a partial pressure of CO 2 in ambient atmosphere.

2. The manufacturing process of claim 1 , wherein the at least one cement component (feedstock) further includes calcium silicate hydrate or a limestone.

3. The manufacturing process of claim 1 , wherein the at least one cement component further includes ordinary portland cement, a calcium sulfoaluminate cement, or a calcium aluminate cement.

4. The manufacturing process of claim 1 , wherein the at least one cement component further includes magnesium hydroxide, magnesium carbonate, or magnesium silicate.

5. The manufacturing process of claim 1 , wherein the exposing in (d) is carried out at a temperature in a range of about 5° C. to about 80° C.

6. The manufacturing process of claim 1 , wherein the exposing in (d) includes converting the at least one cement component to calcium carbonate or magnesium carbonate.

7. The manufacturing process of claim 6 , wherein a mass basis percentage of the at least one cement component converted to calcium carbonate or magnesium carbonate is at least 10% within a reaction residence time period of 6 h.

8. A manufacturing process, comprising:

(a) disposing a reactant in a reactor, wherein the reactant is in a monolithic form and includes portlandite and aggregates, and a water content of the reactant mixture is no greater than 25% by mass;

(b) introducing CO 2 into the reactor; and

(c) exposing the reactant to gaseous CO 2 for a reaction time period to form calcium carbonate,

wherein a partial pressure of the CO 2 present in the reactor is higher than a partial pressure of CO 2 in ambient atmosphere.

9. The manufacturing process of claim 8 , wherein the water content of the reactant mixture is no greater than 20% by mass.

10. The manufacturing process of claim 8 , wherein a mass basis percentage of the reactant converted to calcium carbonate is at least 10% within the reaction time period of 6 h.

11. The manufacturing process of claim 1 , wherein the shaping in (b) includes forming pores to facilitate permeation of CO 2 in the structural element.

12. The manufacturing process of claim 1 , further comprising disposing the structural element in an atmosphere with a relative humidity greater than 8%, and less than 75%, prior to the exposing in (d).

13. The manufacturing process of claim 1 , wherein the exposing the monolithic structural element in the reactor to CO 2 in step (d) results in an accelerated carbonation rate relative to exposing the monolithic structural element in the reactor to ambient atmospheric air.

14. The manufacturing process of claim 8 , wherein the exposing the monolithic structural element in the reactor to CO 2 in step (d) results in an accelerated carbonation rate relative to exposing the monolithic structural element in the reactor to ambient atmospheric air.

15. The manufacturing process of claim 1 , further comprising exposing the structural element in an atmosphere with a relative humidity of about 30% or greater prior to the exposing in (d).

16. The manufacturing process of claim 1 , cement component contains portlandite in an amount of at least about 80% by mass.