US-12623969-B2 - Process for cold sintering of calcium carbonate for precast construction materials

Abstract

Embodiments relate to use of a solution having low molarity to form a mixture with a ceramic compound that will facilitate formation of a sintered ceramic compact exhibiting grain boundary formation, low porosity, adequate compressive strength, and adequate hardness to be used as a precast block 108 for cement.

Inventors

• Aly Said
• Mehrzad Zahabi
• Ali Memari

Assignees

• THE PENN STATE RESEARCH FOUNDATION

Dates

Publication Date

20260512

Application Date

20210715

Claims (18)

1. 1 . A method of forming a sintered composite, the method comprising: combining raw material compounds with an aqueous solution to form a mixture, the raw material compounds including ground calcium carbonate and/or precipitate calcium carbonate mixed with cementing materials; and applying pressure and/or temperature to the mixture to cause the raw material compounds to sinter and generate a sintered material, wherein sintering involves supersaturation of compressed contact zones between grains of the raw material compounds.
2. 2 . The method of claim 1 , wherein the raw material compounds are in powder form.
3. 3 . The method of claim 2 , wherein the raw material compound has a uniform particle size distribution.
4. 4 . The method of claim 2 , wherein the raw material compounds have non-uniform particle size distributions.
5. 5 . The method of claim 1 , wherein the pressure is applied within a range from 10 to 300 MPa.
6. 6 . The method of claim 1 , wherein the temperature is applied within a range from 50 to 250° C.
7. 7 . The method of claim 1 , wherein the cementing materials include Portland cement, calcined clay, silica, and/or clay minerals.
8. 8 . The method of claim 1 , wherein the aqueous solution comprises any one or combination of aqueous sodium hydroxide (NaOH) solution or aqueous sodium chloride (NaCl).
9. 9 . The method of claim 1 , further comprising: forming a precast block or a building unit from the sintered material.
10. 10 . The method of claim 9 , wherein: the precast block includes the raw material compounds, one or more supplemental additives, and fiber; wherein the precast block is formed as a block, a brick, a tile, a masonry unit, a drywall sheet, a countertop material, or an architectural stone.
11. 11 . The method of claim 10 , wherein the binder is-includes a cement pore solution.
12. 12 . The method of claim 10 , further comprising: adding aggregate to the block.
13. 13 . The method of claim 1 , further comprising: adding a supplemental additive to the mixture to any one or combination of: provide alkali ions during sintering; and draw water of the solution into hydration reactions to direct water vapor away from grains of the raw material compounds.
14. 14 . The method of claim 13 , wherein the alkali ions comprise any one or combination of sodium ions (Na + ) and potassium ions (K + ).
15. 15 . The method of claim 13 , wherein the supplemental additive is any one or combination of cement pore solution, calcium hydroxide, and supplementary cementing materials comprising ground granulated blast-furnace slag.
16. 16 . The method of claim 1 , further comprising: heat treating the sintered material close to and less than a decomposition temperature of the raw material compounds.
17. 17 . The method of claim 16 , wherein the raw material compounds include a ceramic or quasi-brittle material with calcium carbonate as a primary compound.
18. 18 . The method of claim 1 , further comprising adding a superplasticizer to the mixture.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. national stage application of International Patent Application No. PCT/US2021/041856, which is related to and claims the benefit of U.S. provisional application No. 62/706,352, filed on Aug. 11, 2020, the entire contents of each is incorporated herein by reference. FIELD OF THE INVENTION Embodiments relate to use of a solution having low molarity to form a mixture with a ceramic compound that will facilitate formation of a sintered ceramic compact exhibiting grain boundary formation, low porosity, adequate compressive strength, and adequate hardness to be used as precast masonry block unit or drywall sheets for construction applications. BACKGROUND OF THE INVENTION Ordinary portland cement (OPC) production accounts for 5-8% of global CO2 emission, predominantly by the heat treatments involved (approx. 1600° C.) and decomposition of limestone and clay. Conventional efforts to reduce the CO2 emissions when producing cement include partial replacement of the cement with supplementary cementing materials (SCMs), limestone calcined clay cement (LC3), alternative cement clinkers such as calcium silicate clinkers sequestrating CO2, and alkali-activated and geopolymer binders. The system can potentially be used in extraterrestrial habitat construction, where transportation of a construction materials manufacturing system is more economic than transportation of constructions materials such as cement. BRIEF SUMMARY OF THE INVENTION Embodiments relate to use of a solution having low molarity to form a mixture with a ceramic compound that will facilitate formation of a sintered ceramic compact exhibiting grain boundary formation, low porosity, adequate compressive strength, and adequate hardness to be used as a precast masonry block in buildings as well as other construction materials applications such as drywall sheets, countertop materials similar to marble or architectural stone. In an exemplary embodiment, a method of forming a sintered ceramic can involve combining a raw material compound with an aqueous solution, the aqueous solution having a molarity up to 1.0M to form a mixture. The method can involve applying pressure and/or temperature to the mixture to cause the compound to sinter and generate a sintered material, wherein sintering involves supersaturation of compressed contact zones between grains of the compound. In some embodiments, the raw material compound is in powder form. In some embodiments, the raw material compound has a uniform particle size distribution. In some embodiments the raw material compound has a non-uniform particle size distribution. In some embodiments, the pressure is applied within a range from 10 to 300 MPa. In some embodiments, the temperature is applied within a range from 100 to 250° C. In some embodiments, the raw material compound is calcium carbonate. In some embodiments, the raw material compound is any one or combination of ground calcium carbonate and precipitated calcium carbonate. In some embodiments, the raw material compound is any one or combination of calcium carbonate, silica, zincite, clay. The material compound can also be any combination of several minerals and/or clays. In some embodiments, the aqueous solution has a molarity of 1.0M. In some embodiments, the aqueous solution comprises any one or combination of aqueous sodium hydroxide (NaOH) solution or aqueous sodium chloride (NaCl). In some embodiments, the method further involves forming a precast block or a building unit from the sintered material. In some embodiments, the precast block includes the raw material compound, a binder, and fiber. In some embodiments the binder is a cement pore solution. In some embodiments, the method further involves adding aggregate to the block. In some embodiments the method further involves adding a supplemental additive to the mixture to any one or combination of: provide alkali ions during sintering; and draw water of the solution into hydration reactions to direct water vapor away from grains of the compound. In some embodiments, the alkali ions comprise any one or combination of sodium ions (Na+) and potassium ions (K+). In some embodiments, the supplemental additive is any one or combination of cement pore solution, calcium hydroxide, and supplementary cementing materials comprises ground granulated blast-furnace slag. In some embodiments, the method further involves heat treating the sintered material close to and less than decomposition temperature of the raw compound. In some embodiments, the raw compound is a ceramic material with calcium carbonate as the primary compound, and the decomposition temperature of the raw compound is close to 550° C. Further features, aspects, objects, advantages, and possible applications of the present invention will become apparent from a study of the exemplary embodiments and examples described below, in combination with the Figures, and the appended claims. BRIE