Set-delayed cement compositions comprising pumice and associated methods

1. A method of forming a set cement, the method comprising:

mixing a set-delayed cement composition with an activator composition to form an activated cement composition;

placing the activated cement composition into a cavity of an injection mold, wherein the injection mold comprises a first part and a second part, and wherein the cavity is defined by an interior surface of the first part and by an interior surface of the second part;

setting the activated cement composition in the injection mold to from a hardened mass; and

separating the first part of the injection mold from the second part of the injection mold to reveal the hardened mass,

wherein the set-delayed cement composition comprises pumice, lime in an amount of about 20% to about 40% by weight of the pumice, water in an amount of about 35% to about 70% by weight of the pumice, and a phosphonic acid set retarder in an amount of about 1% to about 4% by weight of the pumice, wherein the set-delayed cement composition does not contain any additional components that hydraulically set in the presence of water other than the pumice and hydrated lime, wherein the set-delayed cement composition is capable of remaining in a pumpable fluid state for a period of at least one day or longer at room temperature, wherein the activator composition comprises a cement set activator and aluminum sulfate as an accelerator, and wherein after and as a result of the step of mixing, the activated cement composition undergoes said setting so as to form the hardened mass in a time period of about 10 seconds to about 10 minutes.

2. The method of claim 1 , wherein the set delayed cement composition further comprises an additional set retarder selected from the group consisting of a phosphate, a phosphonate, a phosphonic acid, a phosphonic acid derivative, a lignosulfonate, an organic acid, a carboxymethylated hydroxyethylated cellulose, a synthetic co- or ter-polymer comprising sulfonate and carboxylic acid groups, a borate compound, and any mixture thereof.

3. The method of claim 1 , wherein the cement set activator is selected from the group consisting of a zeolite, amine, silicate, Group IA hydroxide, Group IIA hydroxide, monovalent salt, divalent salt, nanosilica, polyphosphate, and any combination thereof.

4. The method of claim 1 , wherein the set-delayed cement composition further comprises a fiber.

5. The method of claim 1 , wherein the set-delayed cement composition further comprises a dispersant selected from the group consisting of a sulfonated-formaldehyde-based dispersant, a polycarboxylated ether dispersant, and any combination thereof.

6. The method of claim 1 , further comprising, prior to the placing step, storing the set-delayed cement composition for a period of at least about 1 day.

7. The method of claim 1 , wherein the cavity comprises a shape selected from the group consisting of a tile, flooring, underlay, a counter, a backsplash, roofing, a shingle, a shale, weatherboard, façade, cladding, an exterior wall, a partition wall, acoustic insulation, thermal insulation, a soffit, a ceiling, an architrave, a brick, a monolithic shape, and any combination thereof.

8. The method of claim 1 , wherein the set-delayed cement composition further comprises a refractory material.

9. The method of claim 1 , wherein the set-delayed cement composition further comprises a dye and/or a bead.

10. A method of forming a molded set cement, the method comprising:

mixing a set-delayed cement composition with an activator composition to form an activated cement composition;

placing the activated cement composition into a cavity of a cast mold, wherein the cast mold comprises a first part and a second part, and wherein the cavity is defined by an interior surface of the first part and by an interior surface of the second part;

setting the activated cement composition in the cast mold to from a hardened mass; and

removing the first part of the cast mold to reveal the hardened mass,

wherein the set-delayed cement composition comprises pumice, lime in an amount of about 20% to about 40% by weight of the pumice, water in an amount of about 35% to about 70% by weight of the pumice, and a phosphonic acid set retarder in an amount of about 1% to about 4% by weight of the pumice, wherein the set-delayed cement composition does not contain any additional components that hydraulically set in the presence of water other than the pumice and hydrated lime, wherein the set-delayed cement composition is capable of remaining in a pumpable fluid state for a period of at least one day or longer at room temperature, wherein the activator composition comprises a cement set activator and aluminum sulfate as an accelerator, and wherein after and as a result of the step of mixing, the activated cement composition undergoes said setting so as to form the hardened mass in a time period of about 10 seconds to about 10 minutes.

11. The method of claim 10 , wherein the set delayed cement composition further comprises an additional set retarder selected from the group consisting of a phosphate, a phosphonate, a phosphonic acid, a phosphonic acid derivative, a lignosulfonate, an organic acid, a carboxymethylated hydroxyethylated cellulose, a synthetic co- or ter-polymer comprising sulfonate and carboxylic acid groups, a borate compound, and any mixture thereof.

12. The method of claim 10 , wherein the cement set activator is selected from the group consisting of a zeolite, amine, silicate, Group IA hydroxide, Group IIA hydroxide, monovalent salt, divalent salt, nanosilica, polyphosphate, and any combination thereof.