Cementitious mixtures, compositions for use in cementitious mixtures, and methods of producing cementitious mixtures

1. A cementitious mixture comprising a cement material and a composite hydrogel-based internal curing agent, wherein the internal curing agent comprises:

a superabsorbent polymer (SAP) hydrogel having a macromolecular network structure; and

particles of at least one pozzolanic material that is chemically incorporated into the macromolecular network structure of the SAP hydrogel wherein the internal curing agent contains 75 to 90 percent by weight of the at least one pozzolanic material incorporated into the SAP hydrogel.

2. The cementitious mixture of claim 1 , wherein the at least one pozzolanic material is selected from the group consisting of Class C fly ash, silica fume, metakaolin, rice husk ash, Class F fly ash, slag, calcined shale, and any combination thereof.

3. The cementitious mixture of claim 1 , wherein the cementitious mixture comprises more than one pozzolanic material chemically incorporated into the macromolecular network structure of the SAP hydrogel.

4. The cementitious mixture of claim 3 , wherein the more than one pozzolanic material is selected from the group consisting of Class C fly ash, silica fume, metakaolin, rice husk ash, Class F fly ash, slag, calcined shale, and any combination thereof.

5. The cementitious mixture of claim 1 , wherein the cementitious mixture further comprises an ungrafted polymer or an additional SAP hydrogel with a different pozzzolanic material that is chemically incorporated into the additional SAP hydrogel.

6. The cementitious mixture of claim 1 , wherein the internal curing agent further comprises ungrafted polymer incorporated into the macromolecular network structure of the SAP hydrogel.

7. The cementitious mixture of claim 1 , wherein the internal curing agent is irregularly-shaped particles.

8. The cementitious mixture of claim 1 , wherein the internal curing agent is spherical-shaped and/or cylindrical-shaped particles.

9. A method of forming the cementitious mixture of claim 1 , the method comprising:

providing a polymer composition that is end-functionalized with a chemically reactive group;

incorporating a chemically reactive functional group on surfaces of a quantity of the particles of the at least one pozzolanic material to form surface-functionalized pozzolanic particles;

chemically reacting the surface-functionalized pozzolanic particles with the polymer composition that is end-functionalized to form a plurality of polymer-grafted pozzolanic particles;

incorporating a cross-linking agent into the plurality of polymer-grafted pozzolanic particles to form the internal curing agent comprising the SAP hydrogel with the at least one pozzolanic material chemically incorporated into the macromolecular network structure of the SAP hydrogel; and

incorporating the internal curing agent into the cement material;

wherein the internal curing agent contains 75 to 90 percent by weight of the at least one pozzolanic material incorporated into the SAP hydrogel.

10. The method of claim 9 , wherein the particles of the at least one pozzolanic material are particles of a first pozzolanic material, the method further comprising chemically reacting the polymer composition with a second type of surface-functionalized particles comprising a second pozzolanic material such that the particles of both the first and second pozzolanic materials are chemically incorporated into the macromolecular network structure of the composite hydrogel-based internal curing agent.

11. The method of claim 9 , wherein the at least one pozzolanic material is selected from the group consisting of Class C fly ash, silica fume, metakaolin, rice husk ash, Class F fly ash, slag, calcined shale, and any combination thereof.

12. The method of claim 9 , wherein the cementitious mixture comprises more than one pozzolanic material chemically incorporated into the macromolecular network structure of the SAP hydrogel.

13. The method of claim 12 , wherein the more than one pozzolanic material is selected from the group consisting of Class C fly ash, silica fume, metakaolin, rice husk ash, Class F fly ash, slag, calcined shale, and any combination thereof.

14. The method of claim 9 , wherein the composite hydrogel is irregularly-shaped, spherical-shaped, and/or cylindrical-shaped particles.

15. A method of forming the cementitious mixture of claim 1 , the method comprising:

providing a fluid medium having a quantity of the particles of the at least one pozzolanic material therein;

incorporating a composition on surfaces of the particles of the at least one pozzolanic material to form surface-functionalized pozzolanic particles;

chemically reacting the surface-functionalized pozzolanic particles with at least one monomer composition and at least one chain-transfer agent to form a plurality of polymer-grafted particles;

incorporating a cross-linking agent into the plurality of polymer-grafted pozzolanic particles to form the internal curing agent comprising the SAP hydrogel with the at least one pozzolanic material chemically incorporated into the macromolecular network structure of the SAP hydrogel; and

incorporating the internal curing agent into the cement material;

wherein the internal curing agent contains 75 to 90 percent by weight of the at least one pozzolanic material incorporated into the SAP hydrogel.

16. The method of claim 15 , wherein the at least one pozzolanic material is selected from the group consisting of Class C fly ash, silica fume, metakaolin, rice husk ash, Class F fly ash, slag, calcined shale, or any combination thereof.