Calcium carbonate-based cementing material as well as preparation method and application thereof
The preparation of calcium carbonate-based gelling materials through amorphous calcium carbonate cold sintering process solves the problems of low strength and long curing cycle in the prior art, and achieves high strength and rapid preparation, which is suitable for green replacement of building materials.
Patent Information
- Application Number
- CN202510476915.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-07-22
AI Technical Summary
During the preparation process, existing calcium carbonate-based building materials have problems such as low strength, long curing cycle and additional ions, which are difficult to meet the high-strength needs of building materials.
Amorphous calcium carbonate is used as the precursor, and calcium carbonate-based gelling materials are prepared under conditions of 60-80°C and 25-50MPa through cold sintering process. The plastic deformation and phase transformation capabilities of amorphous calcium carbonate are used to achieve particle rearrangement and structural densification.
It has achieved rapid preparation of high-strength calcium carbonate-based gelling materials, with compressive strength up to 23MPa, which is suitable for the replacement of building materials, reduces carbon dioxide emissions, and meets green and environmental protection requirements.
Smart Images
Figure CN120349150A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a calcium carbonate-based cementitious material, a preparation method thereof, and an application thereof, belonging to the field of inorganic non-metallic materials Background Art
[0002] Currently, the annual carbon dioxide emissions from the cement industry account for 5% - 8% of anthropogenic carbon dioxide emissions. Most of these emissions come from the production of cement clinker, which is the main binding component of modern concrete. In order to achieve net-zero emissions by 2050, industries such as cement and concrete that are difficult to decarbonize must find mitigation methods. Different from cement, calcium carbonate binders mainly form a firm bond with various materials through the generated calcium carbonate. Compared with the calcination process in cement production, carbon dioxide emissions can be significantly reduced. Calcium carbonate has multiple crystal forms, mainly including amorphous calcium carbonate, vaterite, aragonite, and calcite. Due to the differences in crystal structure and chemical bond characteristics among the polymorphs of calcium carbonate, there are differences in their thermal stability and mechanical properties. Due to the instability of some of these crystal forms, phase transformation can be achieved through the method of dissolution and reprecipitation under the action of pressure, water, temperature, etc., thereby achieving structural densification
[0003] Currently, for calcium carbonate-based building materials, there is a method of continuously pumping calcium bicarbonate solution and forming calcium carbonate by precipitation of the calcium bicarbonate solution to achieve the bonding between calcium carbonate particles, with a strength only reaching 8.6 MPa. There is also a method of adding a crystal form control agent to achieve setting and hardening, but there are still disadvantages such as the introduction of extra ions, a long curing period, and low strength. Therefore, it is necessary to continue to develop a calcium carbonate-based building material that is easy to prepare and has high strength Summary of the Invention
[0004] Object of the Invention: The first object of the present invention is to provide a calcium carbonate-based cementitious material. The second object of the present invention is to provide a preparation method of the calcium carbonate-based cementitious material. The third object of the present invention is to provide the application of the calcium carbonate-based cementitious material in construction
[0005] Technical Solution: The calcium carbonate-based cementitious material described in the present invention is prepared by a cold sintering process using amorphous calcium carbonate as a precursor
[0006] Further, the temperature of the cold sintering process is 60 - 80 °C, and the pressure is 25 - 50 MPa
[0007] The preparation method of the calcium carbonate-based cementitious material described in the present invention includes the following steps
[0008] (1) Synthesize amorphous calcium carbonate using Na2CO3, NaOH, and CaCl2, or extract calcium from calcium-containing alkaline solid waste and then obtain amorphous calcium carbonate through carbonization
[0009] (2) Mix the amorphous calcium carbonate powder with a liquid medium, stir evenly, add it to a mold, and perform cold sintering to obtain the calcium carbonate-based cementitious material.
[0010] Further, in step (1), when using Na2CO3, NaOH, and CaCl2 to synthesize amorphous calcium carbonate, the temperature for synthesizing amorphous calcium carbonate is 3 - 8 °C, and the pH is controlled to be 11.2 - 13.0 when synthesizing crystalline calcium carbonate.
[0011] Further, in step (1), when using Na2CO3, NaOH, and CaCl2 to synthesize amorphous calcium carbonate, the molar ratio of Na2CO3, NaOH, and CaCl2 is (1 - 5):1:1.
[0012] Further, in step (1), stir and mix the NaOH solution and the Na2CO3 solution, quickly add the CaCl2 solution under stirring, immediately filter, wash with isopropanol, and freeze-dry to obtain amorphous calcium carbonate.
[0013] Further, in step (1), the calcium-containing alkaline solid waste is waste concrete or waste wollastonite.
[0014] Further, in step (1), extracting calcium from the calcium-containing alkaline solid waste includes the following steps:
[0015] Dissolve the calcium-containing alkaline solid waste into a solution containing a crystal form control agent, and pass carbon dioxide for carbonization. Among them, the crystal form control agent is polyaspartic acid.
[0016] Even further, the water-solid ratio is 20:1, and the concentration of the solution containing the crystal form control agent is 0.1 - 0.5 mol / L.
[0017] Further, in step (1), the carbonization temperature is 10 - 30 °C, preferably 20 °C, and the carbonization time is below 120 min, preferably 30 min. The longer the time, the easier it is for amorphous calcium carbonate to crystallize into other calcium carbonate crystal forms.
[0018] Further, in step (2), the liquid medium is water and / or calcium bicarbonate solution respectively.
[0019] Further, in step (2), the mass ratio of the amorphous calcium carbonate powder to the liquid medium is (0.1 - 0.5):1.
[0020] The application of the calcium carbonate-based cementitious material described in the present invention in construction.
[0021] Calcium carbonate polymorphs can be densified through processes such as particle rearrangement and dissolution-precipitation under cold sintering conditions. The process of cold sintering of calcium carbonate particles is similar to the process of geological diagenesis. In particular, for the calcium carbonate block obtained by cold sintering amorphous calcium carbonate, after 5 hours of cold sintering, a compressive strength of 23 MPa can be obtained. Due to its excellent plastic deformation ability and dissolution-precipitation ability, amorphous calcium carbonate can achieve particle slip and phase transformation in a short time with the assistance of a liquid phase during the cold sintering process. By continuously dissolving particles and reprecipitating, calcite is formed, and new crystals are continuously precipitated between particles, thereby promoting the densification of the internal structure of the block. The successful preparation of amorphous calcium carbonate-based cold sintered cementitious materials proves the feasibility of using the cold sintering process to prepare calcium carbonate blocks as building materials within a certain period of time. At the same time, it also directly shows that amorphous calcium carbonate has more advantages as a cementitious material compared to other calcium carbonate polymorphs.
[0022] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:
[0023] In the present invention, amorphous calcium carbonate as a precursor can rapidly achieve particle rearrangement and phase transformation during cold sintering due to its superior plastic deformation and phase transformation ability, and thus densify. Using the cold sintering process can achieve the rapid preparation of high-strength calcium carbonate-based cementitious materials. The prepared calcium carbonate-based cementitious materials have a compressive strength of up to 23 MPa and can be used as building materials to replace the use of cement in building materials. Description of the drawings
[0024] Figure 1 Scanning electron microscope image of the amorphous calcium carbonate prepared in Example 1;
[0025] Figure 2 Scanning electron microscope image of the calcium carbonate prepared in Examples 6-8;
[0026] Figure 3 Scanning electron microscope image of the calcium carbonate prepared in Comparative Examples 1-3;
[0027] Figure 4 Compressive strength diagram of the calcium carbonate-based cementitious materials obtained in Examples 1-4;
[0028] Figure 5 Compressive strength diagram of the calcium carbonate-based cementitious materials obtained in Examples 6-8;
[0029] Figure 6 Elastic modulus diagram of different calcium carbonate blocks in Example 5 and Comparative Examples 1-3. Detailed implementation manners
[0030] The technical solutions of the present invention will be further described below with reference to the accompanying drawings.
[0031] Preparation of calcium carbonate in Example 1
[0032] Preparation of amorphous calcium carbonate: Equal volumes of 0.2 mol / L NaOH and 0.1 mol / L Na2CO3 solutions were mechanically stirred together to obtain a NaOH-Na2CO3 solution. Then, under mechanical stirring at 5 °C, a CaCl2 solution with the same volume and molar amount as the Na2CO3 solution (relative to CO3 2- ,) was rapidly added to the NaOH-Na2CO3 solution (at this time, the temperature of the solution was 5 °C and the pH was 11.2 - 13). The product was immediately filtered, washed with isopropanol, and freeze-dried for 24 hours to obtain amorphous calcium carbonate (as Figure 1 shown).
[0033] When the external heating wire heated the mold (inner cavity diameter 2 cm, height 5 cm) to 80 °C, amorphous calcium carbonate was mixed with water at a water-solid ratio of 0.2 and poured into the mold. A universal testing machine was used to apply a load at a rate of 0.05 MPa / s. Once the pressure reached 25 MPa or 50 MPa, it was held for a specified time of 1 minute before unloading at a rate of 0.05 MPa / s. Finally, the mold was cooled to room temperature and removed to obtain 2 groups of calcium carbonate-based cementitious materials.
[0034] Example 2
[0035] The experimental procedure was the same as in Example 1, except that the mold was not heated and the experiment was carried out at room temperature of 20 °C. Amorphous calcium carbonate was mixed with water at a water-solid ratio of 0.2 and poured into the mold. A universal testing machine was used to apply a load at a rate of 0.05 MPa / s. Once the pressure reached 25 MPa or 50 MPa respectively, it was held for a specified time of 1 minute before unloading at a rate of 0.05 MPa / s. Finally, it was removed to obtain 2 groups of calcium carbonate-based cementitious materials.
[0036] Example 3
[0037] The experimental procedure was the same as in Example 1, except that the heating temperature was different.
[0038] When the external heating wire heated the mold to 40 and 60 °C respectively, amorphous calcium carbonate was mixed with water at a water-solid ratio of 0.2 and poured into the mold. A universal testing machine was used to apply a load at a rate of 0.05 MPa / s. Once the pressure reached 50 MPa, it was held for a specified time of 1 minute before unloading at a rate of 0.05 MPa / s. Finally, the mold was cooled to room temperature and removed to obtain calcium carbonate-based cementitious materials.
[0039] Example 4
[0040] The experimental procedure was the same as in Example 3, except that the liquid medium was different.
[0041] When the external heating wire heats the mold to 80 °C, mix amorphous calcium carbonate and calcium bicarbonate solution with a water-to-solid ratio of 0.2 and pour it into the mold. Use a universal testing machine to apply a load at a rate of 0.05 MPa / s. Once the pressure reaches 50 MPa, maintain it for the specified times of 1 minute respectively before unloading at a rate of 0.05 MPa / s. Finally, cool the mold to room temperature and take out to obtain calcium carbonate-based cementitious materials.
[0042] Example 5
[0043] The experimental process is the same as that of Example 1, except that the holding time is different.
[0044] When the external heating wire heats the mold to 80 °C, mix amorphous calcium carbonate and water with a water-to-solid ratio of 0.2 and pour it into the mold. Use a universal testing machine to apply a load at a rate of 0.05 MPa / s. Once the pressure reaches 50 MPa, maintain it for the specified times of 30 minutes, 120 minutes and 300 minutes respectively before unloading at a rate of 0.05 MPa / s. Finally, cool the mold to room temperature and take out to obtain 3 groups of calcium carbonate-based cementitious materials.
[0045] Example 6
[0046] Mix PO42.5 ordinary Portland cement and water according to a water-cement ratio of 0.5, and prepare simulated waste concrete by hardening for more than three months. Grind the waste concrete powder passed through a 200-mesh sieve, dissolve the waste concrete powder at a liquid-to-solid ratio of 20:1 into a polyaspartic acid solution containing 0.25 mol / L, and carbonize under stirring at 300 rpm with a carbon dioxide gas concentration of 99.5% for 2 h at a carbonization temperature of 20 °C to obtain carbonized recycled fine powder containing amorphous calcium carbonate (as shown in A in Figure 2 ), and the cold sintering process is the same as that of Example 1, except that the pressure reaches 50 MPa, and finally obtain calcium carbonate-based cementitious materials.
[0047] Example 7
[0048] The experimental process is the same as that of Example 6, with different dosages of crystal form control agent. Dissolve the waste concrete powder at a liquid-to-solid ratio of 20:1 into a polyaspartic acid solution containing 0.5 mol / L, and carbonize under stirring at 300 rpm with a carbon dioxide gas concentration of 99.5% for 2 h at a carbonization temperature of 20 °C to obtain carbonized recycled fine powder containing amorphous calcium carbonate (as shown in B in Figure 2 ), and the cold sintering process is the same as that of Example 1, except that the pressure reaches 50 MPa, and finally obtain calcium carbonate-based cementitious materials
[0049] Example 8
[0050] The experimental procedure was the same as in Example 6, except that no crystal form control agent was used. Waste concrete powder was dissolved in water at a liquid-solid ratio of 20:1 without adding the crystal form control agent polyaspartic acid solution. Carbon dioxide gas with a concentration of 99.5% was introduced under stirring at 300 rpm for carbonization for 2 h at a carbonization temperature of 20 °C to obtain carbonized recycled fine powder containing calcite (as shown in C in Figure 2 ). The cold sintering process was the same as in Example 1, except that the pressure reached 50 MPa, and finally, calcium carbonate-based cementitious material was obtained. Comparative Example 1
[0051] Preparation of vaterite:
[0052] To synthesize vaterite, a 1 mol / L CaCl2 aqueous solution was prepared in deionized water, and then 1 mol / L NH4Cl was added. At ambient temperature, equal volumes of the CaCl2 solution and the NH4Cl solution were mechanically stirred together to obtain a CaCl2-NH4Cl solution. Under mechanical stirring at 600 rpm, a 2 mol / L K2CO3 aqueous solution with the same volume as the CaCl2 solution was introduced into the CaCl2-NH4Cl solution for 10 minutes. The resulting particles were immediately separated from the solution by filtration, washed twice with ethanol, and dried in a vacuum oven at 70 °C for 24 h to obtain vaterite powder (as shown in A in Figure 3 ).
[0053] When the external heating wire heated the mold (inner cavity diameter of 2 cm and height of 5 cm) to 80 °C, vaterite was mixed with water at a water-solid ratio of 0.2 and poured into the mold. A universal testing machine was used to apply a load at a rate of 0.05 MPa / s. Once the pressure reached 50 MPa, it was held for specified times of 1 minute, 30 minutes, 120 minutes, and 300 minutes before unloading at a rate of 0.05 MPa / s. Finally, the mold was cooled to room temperature, and calcium carbonate block A was taken out.
[0054] Comparative Example 2
[0055] Preparation of aragonite:
[0056] 1 mol / L CaCl2 and K2CO3 solutions were prepared separately. Equal volumes of the CaCl2 solution and the K2CO3 solution were heated to 80 °C for 1 h and then rapidly mixed. The reaction mixture was kept at 80 °C for 30 minutes, stirred vigorously at 600 rpm, and then immediately filtered. The precipitate was washed successively with water and ethanol and dried in a vacuum oven at 70 °C for 24 h to obtain aragonite powder (as shown in B in Figure 3 ).
[0057] When the external heating wire heats the mold (inner cavity diameter is 2 cm and height is 5 cm) to 80 °C, mix aragonite and water at a water-solid ratio of 0.2 and pour it into the mold. Use a universal testing machine to apply a load at a rate of 0.05 MPa / s. Once the pressure reaches 50 MPa, keep it for the specified times of 1 minute, 30 minutes, 120 minutes, and 300 minutes respectively before unloading at a rate of 0.05 MPa / s. Finally, cool the mold to room temperature and take out to obtain calcium carbonate block B.
[0058] Comparative Example 3
[0059] Preparation of calcite:
[0060] To synthesize calcite, quickly mix 1 mol / L aqueous CaCl2 solution with an equal molar amount of 1 mol / L aqueous K2CO3 solution. Then stir the mixture at 600 rpm at room temperature for 24 hours. Wash the obtained particles twice with water and dry them in a vacuum oven at 70 °C for 24 hours to obtain calcite powder (as shown in Figure 3 C).
[0061] When the external heating wire heats the mold (inner cavity diameter is 2 cm and height is 5 cm) to 80 °C, mix calcite and water at a water-solid ratio of 0.2 and pour it into the mold. Use a universal testing machine to apply a load at a rate of 0.05 MPa / s. Once the pressure reaches 50 MPa, keep it for the specified times of 1 minute, 30 minutes, 120 minutes, and 300 minutes respectively before unloading at a rate of 0.05 MPa / s. Finally, cool the mold to room temperature and take out to obtain calcium carbonate block C.
[0062] When using the amorphous calcium carbonate obtained in the above Examples 1-4 as a precursor, the strength of the calcium carbonate-based cementitious material obtained by changing the cold sintering conditions is as shown in Figure 4 shown. It can be seen from Figure 4 that when using calcium bicarbonate solution as the liquid medium, the strength is slightly higher than that of pure water. The temperature has the greatest influence on the strength, followed by the magnitude of the applied pressure.
[0063] When using the calcium carbonate obtained in the above Examples 6-8 as a precursor, the strength of the calcium carbonate-based cementitious material prepared is as shown in Figure 5 shown. It can be seen from Figure 5 that without adding a crystal form control agent, the strength of the prepared calcium carbonate-based cementitious material is much lower than that with the addition of a crystal form control agent.
[0064] When using different calcium carbonate crystal forms of the above Examples 5 and Comparative Examples 1-3 as precursors, the elastic moduli measured by nanoindentation testing are as shown in Figure 6 shown. It can be seen from Figure 6It can be seen that the elastic modulus reflects the plastic deformation ability of calcium carbonate particles, further reflecting that the amorphous calcium carbonate has a strong particle rearrangement ability during the cold sintering process in Example 5.
[0065] When different calcium carbonate crystal forms of the above Example 5 and Comparative Examples 1-3 were used as precursors, the strength and internal pore diameter of the prepared calcium carbonate blocks were respectively tested, and the phase transformation conditions after cold sintering for 5 h were measured by XRD as shown in Table 1.
[0066] Table 1 Compressive strength, pore diameter and phase transformation phase rate of calcium carbonate blocks prepared in Example 5 and Comparative Examples 1-3
[0067]
[0068] As can be seen from Table 1, when amorphous calcium carbonate is used as the precursor in Example 5, a relatively high strength can be obtained after cold sintering for 1 minute, far exceeding other calcium carbonate polymorphs in Comparative Examples 1-3, and it can reach 23 MPa after cold sintering for 300 minutes, achieving the purpose of rapid preparation in a short time. Amorphous calcium carbonate has a higher elastic modulus and phase change ability compared with other calcium carbonate crystal forms as precursors, and can be densified in a short time, reducing the size of the internal pore diameter. This is the key to determining the high strength. The successful preparation of the cold-sintered amorphous calcium carbonate-based cementitious material means that in the future, we can prepare new cementitious materials by cold-sintering technology through the preparation of amorphous calcium carbonate. Amorphous calcium carbonate is widely sourced and can be obtained by carbonization treatment of alkaline solid wastes such as recycled micropowders. Therefore, it has a wide range of applications in the field of building materials, especially in the field of low-carbon building materials.
Claims
1. A calcium carbonate-based cementitious material, characterized in that, The calcium carbonate-based cementitious material is prepared by cold sintering of precursor amorphous calcium carbonate.
2. The calcium carbonate-based cementitious material according to claim 1, characterized in that, The temperature of the cold sintering process is 60 - 80 °C, and the pressure is 25 - 50 MPa.
3. The preparation method of the calcium carbonate-based cementitious material according to claim 1 or 2, characterized in that, It includes the following steps: (1) Synthesize amorphous calcium carbonate using Na2CO3, NaOH, and CaCl2, or obtain amorphous calcium carbonate by carbonization after extracting calcium from calcium-containing alkaline solid waste. (2) Mix the amorphous calcium carbonate powder with a liquid medium, stir evenly, add it to a mold, and perform cold sintering to obtain the calcium carbonate-based cementitious material.
4. The preparation method of the calcium carbonate-based cementitious material according to claim 3, characterized in that, In step (1), the temperature for synthesizing amorphous calcium carbonate is 3 - 8 °C, and the pH is controlled at 11.2 - 13.0 when synthesizing crystalline calcium carbonate.
5. The preparation method of the calcium carbonate-based cementitious material according to claim 3, characterized in that, In step (1), the molar ratio of Na2CO3, NaOH, and CaCl2 is (1 - 5):1:
1.
6. The preparation method of the calcium carbonate-based cementitious material according to claim 3, characterized in that, In step (1), stir and mix the NaOH solution and the Na2CO3 solution, quickly add the CaCl2 solution under stirring, immediately filter, wash with isopropanol, and freeze-dry to obtain amorphous calcium carbonate.
7. The preparation method of the calcium carbonate-based cementitious material according to claim 3, characterized in that, In step (1), the calcium-containing alkaline solid waste is waste concrete or waste wollastonite.
8. The preparation method of the calcium carbonate-based cementitious material according to claim 3, characterized in that, In step (1), the calcium extraction includes the following steps: Dissolve the calcium-containing alkaline solid waste in water containing a crystal form control agent, and pass carbon dioxide for carbonization. Among them, the crystal form control agent is polyaspartic acid, the carbonization temperature is 10 - 30 °C, and the carbonization time is within 120 min.
9. The preparation method of the calcium carbonate-based cementitious material according to claim 3, characterized in that, In step (2), the liquid medium is water and / or calcium bicarbonate solution, and the mass ratio of the amorphous calcium carbonate powder to the liquid medium is (0.1 - 0.5):
1.
10. The application of the calcium carbonate-based cementitious material according to claim 1 or 2 in construction.