Low-grade regenerated micro-powder-based low-carbon portland cement-based material
By preparing low-grade recycled micropowder-based low-carbon silicate cementitious materials, the activity of recycled micropowder is improved by chemical and thermal activation, and a carbon curing accelerator is added. This solves the problem of insufficient activity of low-grade recycled micropowder in cementitious materials, and achieves low-carbon production and performance improvement.
Patent Information
- Application Number
- CN202610018173.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-08
- Publication Date
- 2026-03-20
AI Technical Summary
Low-grade recycled micro powder has insufficient activity in cement-based materials, resulting in slow early strength development and unstable hydration products in the later stage, which limits its high-dosage utilization. In addition, traditional silicate cement production is energy-intensive and has high carbon emissions.
Low-carbon cement clinker was prepared by using low-grade recycled micro powder, and its gelling activity was improved by chemical and thermal activation. A carbonate-type layered bimetallic hydroxide (LDH) matrix and an in-situ grown basic carbonate phase were added as carbon solidification promoters to promote the hydration process and carbon solidification.
It lowers the firing temperature of cement clinker, reduces carbon emissions, improves early strength and volume stability, promotes the efficient utilization of recycled micro powder, and realizes resource utilization and mechanical property improvement.
Smart Images
Figure CN121698617A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of cement materials, specifically to a low-grade recycled micronized powder-based low-carbon silicate cement-based material. Background Technology
[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] Silicate cement, as a major component of building materials, plays a crucial role in global infrastructure construction and economic development. However, the traditional production process of silicate cement typically involves high-temperature calcination (often exceeding 1400°C), which not only consumes a large amount of energy but also generates significant carbon emissions. According to relevant data, the cement industry accounts for approximately 5-8% of global anthropogenic CO2 emissions, making it a key area for achieving a low-carbon transition. To reduce the carbon footprint, researchers have explored ways to utilize industrial waste as raw materials or admixtures to reduce the consumption of natural resources and improve the recycling rate of industrial waste.
[0004] Recycled microparticles (such as waste concrete powder and industrial waste residue) can serve as partial substitutes for cement raw materials. However, low-grade recycled microparticles (with low calcium oxide content, typically 25-30%) have complex compositions, insufficient activity, and numerous impurities. This limits their inclusion ratio in cement production to below 10%, as this can easily lead to incomplete clinker mineral phase formation, reduced strength, or poor volume stability. Furthermore, due to the generally low cementitious activity of recycled microparticles, their direct incorporation into cementitious materials can result in slow early strength development and unstable hydration products in later stages, affecting the overall performance of the cement and limiting the utilization of low-grade recycled microparticles. Summary of the Invention
[0005] This invention provides a low-grade recycled micron powder-based low-carbon silicate cementitious material. It not only utilizes low-carbon cement clinker prepared from low-grade recycled micron powder to replace traditional low-carbon cement clinker, achieving waste resource utilization while reducing carbon emissions, but also enhances the cementitious activity of the recycled micron powder through chemical and thermal activation methods, further promoting its utilization in cementitious materials. Specifically, the technical solution of this invention is as follows.
[0006] A low-grade recycled micronized powder-based low-carbon silicate cementitious material comprises the following components in the following proportions: 50-70 parts by weight of low-carbon cement clinker, 30-50 parts by weight of active recycled micronized powder admixture, and 0.5-5 parts by weight of carbon curing accelerator. The carbon curing accelerator comprises a carbonate-type layered bimetallic hydroxide (LDH) matrix and a basic carbonate phase grown in situ on the surface of the matrix, wherein the metal element in the basic carbonate phase is homologous to the metal element in the layered bimetallic hydroxide.
[0007] Furthermore, the specific surface area of the active recycled micro powder admixture is 400~700m². 2 / kg.
[0008] Furthermore, the particle size of the layered bimetallic hydroxide (LDH) matrix is 5~50 μm.
[0009] Furthermore, the basic carbonate phase includes at least one of basic calcium carbonate, basic magnesium carbonate, and basic calcium magnesium carbonate.
[0010] Furthermore, the mass fraction of the basic carbonate phase is 5~40 wt.%.
[0011] Furthermore, the carbon curing accelerator is prepared by the following method: (1) Ca 2+ and / or Mg 2+ Aqueous solution of source with Al 3+ or Fe 3+ The aqueous solution of the source was mixed in proportion and then an alkaline solution and a carbonate ion source were added. The mixture was then heated to react, and a layered bimetallic hydroxide (LDH) system was obtained after the reaction was completed. (2) CO2 gas was introduced into the system to allow the basic carbonate phase to be deposited and grown in situ on the LDH surface. After the reaction was completed, the solid product was separated and dried to obtain the carbon curing accelerator.
[0012] Further, in step (1), the Ca 2+ The source includes at least one of calcium chloride, calcium nitrate, etc. The Mg... 2+ The source includes at least one of magnesium chloride, magnesium nitrate, etc. The Al 3+ The source includes at least one of aluminum chloride, aluminum nitrate, etc. The Fe... 3+ The sources include at least one of ferric chloride, ferric nitrate, etc.
[0013] Further, in step (1), the Ca 2+ and / or Mg 2+ Source and Al 3+ or Fe 3+ The molar ratio of the source is 2~4:1.
[0014] Further, in step (1), the alkaline solution is added to maintain the pH of the system between 10 and 12. Optionally, the alkaline solution includes at least one of NaOH, KOH solution, etc.
[0015] Further, in step (1), the carbonate ion source includes at least one of Na₂CO₃, K₂CO₃, etc. Optionally, the CO₃²⁻ provided by the carbonate ion source... 2- With the Al 3+ or Fe 3+ The molar ratio is 0.3~3:1.
[0016] Further, in step (1), the heating temperature is 40~80℃, and the reaction time is 4~24 hours. During this process, Ca... 2+ and / or Mg 2+ With Al 3+ or Fe 3+ Layered bimetallic hydroxides (LDHs) with regular layered structures are formed in an alkaline environment where carbonates coexist, providing a stable support and raw materials for the subsequent in-situ growth of basic carbonate phases.
[0017] Further, in step (2), the CO2 gas is introduced at a rate of 0.1~0.5 L / min for 1~6 hours. Optionally, the temperature of the reaction system during the formation of the basic carbonate phase is controlled between 30~60℃.
[0018] Furthermore, in step (2), the drying temperature is 80~120℃ and the time is 12~24h.
[0019] Further, the active regenerated micro powder admixture is prepared by the following method: (S1) A silica modifier and saturated lime water are added to a slurry formed by regenerated micro powder and water, mixed well, and then heated to react. (S2) The solid product is then separated, washed to remove free alkali and soluble salts, and then dried and ground to obtain the active regenerated micro powder admixture.
[0020] Further, in step (S1), the mass ratio of the recycled micro-powder to water is 5-10:1. Optionally, the recycled micro-powder includes at least one of waste concrete powder, waste clay brick powder, etc., with a specific surface area of 300-500 m². 2 / kg.
[0021] Further, in step (S1), the mass ratio of the silica modifier to the regenerated micro powder is 0.05~0.3:1. Optionally, the silica modifier includes at least one of the following: tetraethyl orthosilicate, methyl orthosilicate, polyethoxydisiloxane, silica sol, water glass, sodium silicate solution, etc.
[0022] Further, in step (S1), the mass ratio of the saturated lime water to the regenerated micro powder is 0.5~6:1.
[0023] Further, in step (S1), the heating temperature is 80~100℃ and the reaction time is 0.5~3 hours.
[0024] Furthermore, in step (S2), the drying temperature is 80~120°C, and the product is dried until the moisture content is less than 1 wt%.
[0025] Furthermore, the low-carbon cement clinker is prepared by the following method: The components are mixed in a ratio of 10-30 parts by weight of recycled micro-powder, 68-73 parts by weight of calcareous powder, and 0.3-2 parts by weight of siliceous powder, and then calcined at 1330-1380℃ for 10-30 minutes. After calcination, the mixture is rapidly cooled and then ground to obtain the low-carbon cement clinker.
[0026] Furthermore, in the preparation process of the low-carbon cement clinker, the recycled micro-powder includes at least one of waste concrete powder, waste clay brick powder, etc. Optionally, the specific surface area of the recycled micro-powder is 300~500m². 2 / kg.
[0027] Furthermore, in the preparation process of the low-carbon cement clinker, the calcareous powder includes at least one of the following: calcium carbonate powder, limestone powder, marble powder, and carbide slag powder; optionally, the specific surface area of the calcareous powder is 200~300m². 2 / kg.
[0028] Furthermore, in the preparation process of the low-carbon cement clinker, the siliceous powder includes at least one of bauxite, high-alumina fly ash, and aluminum slag. Optionally, the specific surface area of the aluminous powder is 200-300 m² / g. 2 / kg.
[0029] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: (1) The present invention utilizes low-grade recycled micro powder formed from solid waste to prepare low-carbon cement clinker, which not only significantly reduces the clinker firing temperature, achieving a dual reduction in energy consumption and carbon emissions, but also provides the resulting low-carbon cement clinker with early strength, rapid hardening, and good volume stability. This is because the recycled micro powder contains a certain amount of active silicate minerals and fluxing components, thus allowing cement clinker with the target mineral composition to be obtained at a firing temperature of 1330~1380℃, which is about 40~80℃ lower than the traditional calcination temperature of over 1400℃. At the same time, the recycled micro powder reduces the use of natural limestone, thereby reducing CO2 emissions caused by limestone decomposition during the firing process. In addition, because the low-carbon cement clinker contains a high content of C3S and C2S, the low-carbon cement clinker of the present invention not only has the characteristics of early strength and rapid hardening, but also has good volume stability, preventing problems such as later expansion, cracking, and strength deterioration caused by free CaO / MgO.
[0030] (2) This invention utilizes saturated lime water to promote the hydrolysis and condensation of the silica modifier, while simultaneously utilizing the Ca gradually dissolved from the regenerated micro powder. 2+ Al 3+ SiO4 formed with silicon modifier 4- The reactive ions react to form nanoscale CSH / CASH gel cores in situ on and around the surface of the recycled micropowder particles, creating an active coating layer and dispersed hydration seed phases. This effectively promotes the early hydration of C3S and C2S, significantly improving compressive strength while allowing for full development of later strength. This not only transforms low-grade recycled micropowder, which is difficult to utilize in high doses, into a highly active admixture, achieving resource utilization, but also promotes the mechanical properties of the cement-based material of this invention.
[0031] (3) The cement-based material of the present invention also incorporates a carbonation accelerator composed of a carbonate-type layered bimetallic hydroxide (LDH) matrix and a basic carbonate phase grown in situ on the surface of the matrix. This special structure and composition of the additive can utilize the matrix to provide a large number of alkaline sites and anion exchange sites, thereby affecting the pH and CO3 of the system during hydration and carbonation. 2- The HCO3⁻ concentration acts as a buffer and regulator. On the other hand, utilizing carbon dioxide not only transforms calcium and magnesium ions in the reaction system into a stable and dense basic carbonate phase grown in situ on the matrix surface, achieving the solidification and high-value utilization of carbon dioxide and reducing carbon emissions, but also ensures a tight interfacial bond between the basic carbonate phase and the matrix, thus preventing its detachment. This basic carbonate phase provides heterogeneous nucleation centers for the formation of hydration products such as CSH in cement clinker, accelerating the hydration process and improving the mechanical properties of cement-based materials. Attached Figure Description
[0032] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention.
[0033] Figure 1 The image shows a sample of low-carbon cement clinker prepared in Example 1 below.
[0034] Figure 2 The image shows a sample of the active regenerated micro powder admixture prepared in Example 1 below.
[0035] Figure 3 The image shows a sample of the carbon curing accelerator prepared in Example 1 below. Detailed Implementation
[0036] The technical solution of the present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.
[0037] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means. Unless otherwise specified, the reagents or raw materials used in this invention are used in accordance with conventional methods in the art or according to the product instructions. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.
[0038] Example 1: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: 1. Preparation of low-carbon cement clinker: According to the recycled micro powder (specific surface area of 417.6 m²), 2 / kg of waste concrete powder), calcium carbonate powder (specific surface area of 228.4m²) 2 / kg), bauxite (specific surface area of 246.9m²) 2 The components were mixed in a ratio of 25 parts by weight: 71.4 parts by weight: 1.2 parts by weight ( / kg). The mixture was then heated to 1350℃ at a heating rate of 10℃ / min and calcined for 20 min. After calcination, it was air-cooled to room temperature, and the resulting solid was then ground to obtain a specific surface area of 380.3 m². 2 / kg of low-carbon cement clinker (such as Figure 1 (As shown), for later use.
[0039] 2. Preparation of active recycled micro powder admixtures: (S1) The recycled micro powder (specific surface area of 417.6 m²) 2 / kg of waste concrete powder was mixed with water at a mass ratio of 6.5:1 and stirred to form a uniform slurry. Then, a silica modifier (ethyl orthosilicate) and saturated lime water were added to the slurry. The mass ratio of the silica modifier to the recycled micro powder was 0.15:1, and the mass ratio of the saturated lime water to the recycled micro powder was 3:1. After completion, the mixture was heated to 85°C and stirred for 2 hours.
[0040] (S2) Then, the solid-liquid mixture is filtered for separation. The resulting solid product is washed with water to remove free alkali and soluble salts, then heated to 100°C and dried until the moisture content is less than 1 wt%. Finally, it is ground to obtain a product with a specific surface area of 597.1 m². 2 / kg of active recycled micro powder admixture (such as Figure 2 (As shown), for later use.
[0041] 3. Preparation of carbon curing accelerator: (1) Mix the aqueous solution of magnesium chloride and the aqueous solution of aluminum chloride according to the Mg... 2+ Al 3+ The components were mixed in a molar ratio of 3.2:1 and stirred until homogeneous. Then, sodium hydroxide solution was added to maintain the pH of the system between 10 and 12. Next, Na₂CO₃ was added and stirred until homogeneous, providing CO₃²⁻. 2- With the Al 3+ The molar ratio was 2.5:1. After completion, the reaction was heated to 60°C for 15 hours to obtain a reaction system containing layered bimetallic hydroxide (LDH).
[0042] (2) CO2 gas was continuously introduced into the system at a rate of 0.2 L / min for 4 hours, and the temperature of the reaction system was set to 50°C. After completion, the solid product was filtered out and dried at 100°C for 18 hours. The carbon curing accelerator (e.g., Figure 3 (As shown).
[0043] 4. Take the following components in the following proportions: 58 parts by weight of low-carbon cement clinker, 42 parts by weight of active recycled micro-powder admixture, and 3.5 parts by weight of carbon curing accelerator. Mix the above components evenly to obtain the cement-based material.
[0044] Performance Testing: Cement-based materials prepared in this embodiment were made into specimens according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-2021). These specimens were then carbonized for 24 hours at 20±1℃, 55% humidity, and 90% CO2 concentration. After carbonation, the specimens were transferred to a curing chamber for standard curing. The flexural and compressive strengths were then tested at 3d, 7d, and 28d of curing. The results are shown in the table below.
[0045] Example 2: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: 1. Preparation of low-carbon cement clinker: According to the recycled micro powder (specific surface area of 485.2 m²), 2 / kg of waste concrete powder), limestone powder (specific surface area of 295.1m³). 2 / kg), high-alumina fly ash (specific surface area of 302.3m³). 2 The mixture was prepared by mixing 10 parts by weight ( / kg) of the powder with a weight ratio of 68 parts by weight to 0.3 parts by weight. The mixture was then heated to 1330°C at a heating rate of 10°C / min and calcined for 30 min. After calcination, the powder was air-cooled to room temperature, and then ground to obtain a specific surface area of 407.9 m². 2 / kg of low-carbon cement clinker, for later use.
[0046] 2. Preparation of active recycled micro powder admixtures: (S1) The regenerated micro powder (specific surface area of 485.2 m²) 2 / kg of waste concrete powder is mixed with water at a mass ratio of 10:1 to form a uniform slurry. Then, a silica modifier (silica sol) and saturated lime water are added to it. The mass ratio of the silica modifier to the recycled micro powder is 0.05:1, and the mass ratio of the saturated lime water to the recycled micro powder is 0.5:1. After completion, the mixture is heated to 80°C and stirred for 3 hours.
[0047] (S2) Then, the solid-liquid mixture is filtered for solid-liquid separation. The obtained solid product is washed with water to remove free alkali and soluble salts, then heated to 80°C and dried until the moisture content is less than 1 wt%. Finally, it is ground to obtain a product with a specific surface area of 706.7 m². 2 / kg of active recycled micro powder admixture, for later use.
[0048] 3. Preparation of carbon curing accelerator: (1) Mix calcium nitrate aqueous solution and aluminum nitrate aqueous solution according to Ca 2+ Al 3+ The components were mixed in a molar ratio of 2.5:1 and stirred until homogeneous. Then, sodium hydroxide solution was added to maintain the pH of the system between 10 and 12. Next, Na₂CO₃ was added and stirred until homogeneous, providing CO₃²⁻. 2- With the Al 3+ The molar ratio was 0.3:1. After completion, the reaction was heated to 80°C for 4 hours to obtain a reaction system containing layered bimetallic hydroxide (LDH).
[0049] (2) CO2 gas was continuously introduced into the system at a rate of 0.5 L / min for 1 hour, and the temperature of the reaction system was set to 60 °C. After completion, the solid product was filtered out and dried at 120 °C for 12 hours. The carbon curing accelerator was obtained.
[0050] 4. Take the following components in the following proportions: 70 parts by weight of low-carbon cement clinker of this embodiment, 50 parts by weight of active recycled micro powder admixture of this embodiment, and 5 parts by weight of carbon curing accelerator of this embodiment. Mix the above components evenly to obtain the cement-based material.
[0051] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0052] Example 3: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: 1. Preparation of low-carbon cement clinker: According to the recycled micro powder (specific surface area of 304.4 m²), 2 / kg of waste concrete powder), calcium carbide slag powder (specific surface area of 223.5m²) 2 / kg), aluminum slag (specific surface area of 214.8m²) 2 The mixture was prepared by mixing 30 parts by weight ( / kg) of the solid with 73 parts by weight (: 2 parts by weight). The mixture was then heated to 1380°C at a rate of 10°C / min and calcined for 10 min. After calcination, the solid was air-cooled to room temperature, and then ground to obtain a specific surface area of 392.4 m². 2 / kg of low-carbon cement clinker, for later use.
[0053] 2. Preparation of active recycled micro powder admixtures: (S1) The recycled micro powder (specific surface area of 304.4 m²) 2 / kg of waste concrete powder is mixed with water at a mass ratio of 5:1 to form a uniform slurry. Then, a silica modifier (polyethoxydisiloxane) and saturated lime water are added to it. The mass ratio of the silica modifier to the recycled micro powder is 0.3:1, and the mass ratio of the saturated lime water to the recycled micro powder is 6:1. After completion, the mixture is heated to 100°C and stirred for 0.5 hours.
[0054] (S2) Then, the solid-liquid mixture is filtered for separation. The resulting solid product is washed with water to remove free alkali and soluble salts. It is then heated to 120°C and dried until the moisture content is less than 1 wt%. Finally, it is ground to obtain a product with a specific surface area of 411.2 m². 2 / kg of active recycled micro powder admixture, for later use.
[0055] 3. Preparation of carbon curing accelerator: (1) Mix the aqueous solutions of magnesium nitrate, calcium nitrate, and aluminum nitrate according to Mg 2+ Ca 2+ Al 3+The components were mixed in a molar ratio of 1:1:1 and stirred until homogeneous. Then, sodium hydroxide solution was added to maintain the pH of the system between 10 and 12. Next, Na₂CO₃ was added and stirred until homogeneous, providing CO₃²⁻. 2- With the Al 3+ The molar ratio was 3:1. After completion, the reaction was heated to 40°C for 24 hours to obtain a reaction system containing layered bimetallic hydroxide (LDH).
[0056] (2) CO2 gas was continuously introduced into the system at a rate of 0.1 L / min for 6 hours, and the temperature of the reaction system was set to 30 °C. After completion, the solid product was filtered out and dried at 80 °C for 24 hours to obtain the carbon curing accelerator.
[0057] 4. Take the following components in the following proportions: 50 parts by weight of low-carbon cement clinker of this embodiment, 30 parts by weight of active recycled micro powder admixture of this embodiment, and 0.5 parts by weight of carbon curing accelerator of this embodiment. Mix the above components evenly to obtain the cement-based material.
[0058] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0059] Example 4: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: 1. Preparation of carbon curing accelerator: Magnesium chloride aqueous solution and aluminum chloride aqueous solution are mixed according to the Mg... 2+ Al 3+ The components were mixed in a molar ratio of 3.2:1 and stirred until homogeneous. Then, sodium hydroxide solution was added to maintain the pH of the system between 10 and 12. Next, Na₂CO₃ was added and stirred until homogeneous, providing CO₃²⁻. 2- With the Al 3+ The molar ratio is 2.5:1. After completion, the reaction is heated to 60℃ for 15 hours to obtain a reaction system containing layered bimetallic hydroxide (LDH). The solid product is then filtered out and dried at 100℃ for 18 hours to obtain the carbon curing accelerator.
[0060] 2. Take the following components in the following proportions: 58 parts by weight of the low-carbon cement clinker from Example 1 above, 42 parts by weight of the active recycled micro-powder admixture from Example 1 above, and 3.5 parts by weight of the carbon curing accelerator from this example. Mix the above components evenly to obtain the cement-based material.
[0061] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0062] Example 5: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: The following components were selected: 70 parts by weight of the low-carbon cement clinker from Example 2 above, and recycled micro powder (with a specific surface area of 485.2 m²). 2 50 parts by weight of ( / kg) and 5 parts by weight of the carbon curing accelerator of Example 2 above. Mix the above components evenly to obtain the cement-based material.
[0063] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0064] Example 6: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: The following components were selected: 50 parts by weight of 42.5% ordinary silicate cement clinker, 42 parts by weight of the active recycled micro-powder admixture of Example 1, and 3.5 parts by weight of the carbon curing accelerator of Example 1. The above components were mixed evenly to obtain the cement-based material.
[0065] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0066] Example 7: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: 1. Preparation of carbon curing accelerator: (1) Mix calcium nitrate aqueous solution and aluminum nitrate aqueous solution according to Ca 2+ Al 3+ The components were mixed in a molar ratio of 2.5:1 and stirred until homogeneous. Then, sodium hydroxide solution was added to maintain the pH of the system between 10 and 12. Next, Na₂CO₃ was added and stirred until homogeneous, providing CO₃²⁻. 2- With the Al 3+ The molar ratio was 0.3:1. After completion, the reaction was heated to 80°C for 4 hours to obtain a reaction system containing layered bimetallic hydroxide (LDH). The solid product was then filtered off and dried at 120°C for 12 hours to obtain the layered bimetallic hydroxide.
[0067] (2) The layered bimetallic hydroxide and basic calcium magnesium carbonate powder are mixed at a mass ratio of 1:2 and stirred evenly to obtain a carbon curing accelerator.
[0068] 2. Take the following components in the following proportions: 70 parts by weight of the low-carbon cement clinker from Example 2 above, 50 parts by weight of the active recycled micro powder admixture from Example 2 above, and 5 parts by weight of the carbon curing accelerator from this example. Mix the above components evenly to obtain the cement-based material.
[0069] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0070] Example 8: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: 1. Preparation of active recycled micro powder admixtures: (S1) The recycled micro powder (specific surface area of 304.4 m²) 2 / kg of waste concrete powder is mixed with water at a mass ratio of 5:1 to form a uniform slurry. Then, saturated lime water is added to the slurry at a mass ratio of 6:1 to the recycled powder. After completion, the mixture is heated to 100°C and stirred for 0.5 hours.
[0071] (S2) Then, the solid-liquid mixture is filtered for separation. The resulting solid product is washed with water to remove free alkali and soluble salts. It is then heated to 120°C and dried until the moisture content is less than 1 wt%. Finally, it is ground to obtain a product with a specific surface area of 411.2 m². 2 / kg of active recycled micro powder admixture, for later use.
[0072] 2. Take the following components in the following proportions: 50 parts by weight of the low-carbon cement clinker from Example 3 above, 30 parts by weight of the active recycled micro powder admixture from this example, and 0.5 parts by weight of the carbon curing accelerator from Example 3 above. Mix the above components evenly to obtain the cement-based material.
[0073] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0074] Example 9: A method for preparing a low-grade recycled micronized powder-based low-carbon silicate cementitious material, comprising the following steps: 1. Preparation of active recycled micro powder admixtures: (S1) The regenerated micro powder (specific surface area of 485.2 m²) 2 / kg of waste concrete powder is mixed with water at a mass ratio of 10:1 to form a uniform slurry. Then, a silica modifier (silica sol) is added to the slurry at a mass ratio of 0.05:1 to the recycled micro powder. After completion, the mixture is heated to 80°C and stirred for 3 hours.
[0075] (S2) Then, the solid-liquid mixture is filtered for solid-liquid separation. The obtained solid product is washed with water to remove free alkali and soluble salts, then heated to 80°C and dried until the moisture content is less than 1 wt%. Finally, it is ground to obtain a product with a specific surface area of 706.7 m². 2 / kg of active recycled micro powder admixture, for later use.
[0076] 2. Take the following components in the following proportions: 70 parts by weight of the low-carbon cement clinker from Example 2 above, 50 parts by weight of the active recycled micro powder admixture from this example, and 5 parts by weight of the carbon curing accelerator from Example 2 above. Mix the above components evenly to obtain the cement-based material.
[0077] Performance testing: The flexural strength and compressive strength of the cement-based material prepared in this embodiment were tested using the same methods as in Example 1 above. The results are shown in the table below:
[0078] The above are merely some preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A low-grade recycled micronized powder-based low-carbon silicate cement-based material, characterized in that, The product comprises the following components in the following proportions: 50-70 parts by weight of low-carbon cement clinker, 30-50 parts by weight of active recycled micro powder admixture, and 0.5-5 parts by weight of carbon curing accelerator; the carbon curing accelerator comprises a carbonate-type layered bimetallic hydroxide matrix and a basic carbonate phase grown in situ on the surface of the matrix, wherein the metal element in the basic carbonate phase is homologous to the metal element in the layered bimetallic hydroxide.
2. The low-grade recycled micronized powder-based low-carbon silicate cement-based material according to claim 1, characterized in that, The specific surface area of the active recycled micro powder admixture is 400~700 m². 2 / kg; optionally, the particle size of the layered bimetallic hydroxide matrix is 5~50μm.
3. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to claim 1, characterized in that, The basic carbonate phase includes at least one of basic calcium carbonate, basic magnesium carbonate, and basic calcium magnesium carbonate; optionally, the mass fraction of the basic carbonate phase is 5~40 wt.%.
4. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to any one of claims 1-3, characterized in that, The carbon curing accelerator is prepared using the following method: (1) Ca 2+ and / or Mg 2+ Aqueous solution of source with Al 3+ or Fe 3+ The aqueous solution of the source is mixed in proportion, and then an alkaline solution and a carbonate ion source are added. The reaction is then heated to obtain a layered bimetallic hydroxide system. (2) CO2 gas is introduced into the system to allow the basic carbonate phase to be deposited and grown in situ on the surface of the layered bimetallic hydroxide; after completion, the solid product is separated and dried to obtain the carbon curing accelerator.
5. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to claim 4, characterized in that, In step (1), the Ca 2+ The source includes at least one of calcium chloride and calcium nitrate; Optionally, in step (1), the Mg 2+ The sources include at least one of magnesium chloride and magnesium nitrate; Optionally, in step (1), the Al 3+ The source includes at least one of aluminum chloride and aluminum nitrate; Optionally, in step (1), the Fe 3+ The source includes at least one of ferric chloride and ferric nitrate; Optionally, in step (1), the Ca 2+ and / or Mg 2+ Source and Al 3+ or Fe 3+ The molar ratio of the sources is 2~4:1; Optionally, in step (1), the alkaline solution is added to maintain the pH of the system between 10 and 12; Optionally, in step (1), the alkaline solution includes at least one of NaOH and KOH solutions; Optionally, in step (1), the carbonate ion source includes at least one of Na2CO3 and K2CO3; Optionally, in step (1), the CO3 provided by the carbonate ion source 2- With the Al 3+ or Fe 3+ The molar ratio is 0.3~3:1; Optionally, in step (1), the heating temperature is 40~80℃ and the reaction time is 4~24 hours.
6. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to claim 4, characterized in that, In step (2), the CO2 gas is introduced at a rate of 0.1 to 0.5 L / min and for a duration of 1 to 6 hours. Optionally, in step (2), the temperature of the reaction system during the formation of the basic carbonate phase is controlled between 30 and 60°C; Optionally, in step (2), the drying temperature is 80~120℃ and the time is 12~24h.
7. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to any one of claims 1-3, characterized in that, The active regenerated micro powder admixture is prepared by the following method: (S1) Add silica modifier and saturated lime water to the slurry formed by the regenerated micro powder and water, mix well and then heat to react; (S2) After separating the solid product, wash to remove free alkali and soluble salts, then dry and grind to obtain active regenerated micro powder admixture.
8. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to claim 7, characterized in that, In step (S1), the mass ratio of the regenerated micro powder to water is 5~10:1; Optionally, in step (S1), the recycled micro powder includes at least one of waste concrete powder and industrial solid waste powder, with a specific surface area of 300-500 m². 2 / kg; Optionally, in step (S1), the mass ratio of the silica modifier to the regenerated micro powder is 0.05~0.3:1; Optionally, in step (S1), the silica modifier includes at least one of: tetraethyl orthosilicate, methyl orthosilicate, polyethoxydisiloxane, silica sol, water glass, and sodium silicate solution; Optionally, in step (S1), the mass ratio of the saturated lime water to the regenerated micro powder is 0.5~6:1; Optionally, in step (S1), the heating temperature is 80~100℃ and the reaction time is 0.5~3 hours; Optionally, in step (S2), the drying temperature is 80~120°C, and the drying is carried out until the moisture content is less than 1 wt%.
9. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to any one of claims 1-3, characterized in that, The low-carbon cement clinker is prepared by the following method: the components are mixed in a ratio of 10-30 parts by weight of recycled micro powder, 68-73 parts by weight of calcareous powder, and 0.3-2 parts by weight of silica powder, and then calcined at 1330-1380℃ for 10-30 minutes; after completion, it is rapidly cooled and then ground to obtain the low-carbon cement clinker.
10. The low-grade recycled micronized powder-based low-carbon silicate cementitious material according to claim 9, characterized in that, In the preparation process of the low-carbon cement clinker, the recycled micro powder includes at least one of waste concrete powder and industrial solid waste powder. Optionally, the specific surface area of the regenerated micro powder is 300~500m². 2 / kg; Optionally, the calcium powder includes at least one of the following: calcium carbonate powder, limestone powder, marble powder, and carbide slag powder; Optionally, the specific surface area of the calcium powder is 200-300 m². 2 / kg; Optionally, in the preparation process of the low-carbon cement clinker, the siliceous powder includes at least one of bauxite, high-alumina fly ash, and aluminum slag. Optionally, the specific surface area of the aluminum powder is 200~300m². 2 / kg.