A solid waste-based nano-hydrated calcium silicate nucleating agent, its preparation method, and its application in low-heat cement.
By preparing a nano-hydrated calcium silicate nucleating agent based on carbide slag and yellow phosphorus slag, the problems of early strength and drying shrinkage of low-heat cement were solved, realizing the application of low-cost and high-efficiency nucleating agents, which are suitable for railway engineering in western plateau regions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA BUILDING MATERIALS ACADEMY CO LTD
- Filing Date
- 2023-06-20
- Publication Date
- 2026-06-30
Smart Images
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of building materials technology, and in particular relates to a solid waste-based nano-hydrated calcium silicate nucleating agent, its preparation method and application. Background Technology
[0002] Low-heat cement exhibits low heat of hydration and significant late-stage strength gain, and has been successfully applied in hydraulic dams without causing temperature cracks. However, its use in railway engineering requires faster early strength and lower drying shrinkage. Developing an environmentally friendly, energy-saving, and low-carbon admixture is therefore of great significance for improving the quality of railway engineering projects.
[0003] Currently, methods to improve the early strength of low-heat cement include accelerators and quick-setting agents, but these reduce the later strength of the cement. Methods to reduce the drying shrinkage of low-heat cement include adding expansive agents and superabsorbent polymers, but these have a weak effect on promoting early strength. There are also general nucleating agents, which can only improve early strength.
[0004] In existing technologies, such as CN105753000A published by the State Intellectual Property Office, "A method for preparing hydrated calcium silicate seed crystals and its application method," hydrated calcium silicate seed crystals are synthesized using high-purity calcium oxide, sodium silicate / diatomaceous earth, and polycarboxylic acid polymer templates. The main adjustments are made to the calcium-to-silicon ratio, water-to-solid ratio, and dispersant dosage, adjusting process parameters to select the optimal product. Hydrated calcium silicate seed crystals prepared by this method can, to some extent, meet the application requirements of cementitious composite materials. However, the raw materials used in this technique are analytical grade samples, resulting in high production costs. Furthermore, the performance of this product cannot meet the demands of the complex environment of the western plateau region, making it unsuitable for railway engineering operations.
[0005] With my country's continuous efforts to comprehensively manage industrial solid waste, using industrial solid waste to prepare building material admixtures is one of the effective means of solid waste treatment. The production of acetylene gas in my country generates a large amount of calcium carbide slag as a byproduct; approximately 1.2 tons of calcium carbide slag are produced for every 1 ton of calcium carbide consumed. The main component of calcium carbide slag is calcium hydroxide, a valuable calcium resource. Yellow phosphorus slag is a solid byproduct generated during the production of yellow phosphorus; 8-10 tons of yellow phosphorus slag are produced for every 1 ton of yellow phosphorus produced. The main components of yellow phosphorus slag are silicon dioxide and calcium oxide.
[0006] Therefore, based on existing technologies, optimizing and formulating admixtures with solid waste-based materials as the main ingredient to improve the early strength and drying shrinkage resistance of low-heat cement is of great practical significance. Summary of the Invention
[0007] The present invention aims to solve at least one of the technical problems existing in the prior art.
[0008] The technical solution of the present invention is: a solid waste-based nano-hydrated calcium silicate nucleating agent, comprising the following components by weight: 10-30 parts of carbide slag, 20-45 parts of yellow phosphorus slag, and 400-2000 parts of sodium hydroxide solution.
[0009] The calcium hydroxide content in the carbide slag is ≥80%.
[0010] The yellow phosphorus slag contains ≥35% silica and ≥40% calcium oxide.
[0011] The pH value of the sodium hydroxide solution is 11-12.
[0012] A method for preparing a solid waste-based nano-hydrated calcium silicate nucleating agent includes the following steps:
[0013] Step 1: The carbide slag and yellow phosphorus slag are mixed according to the weight proportions and then ground to a particle size of less than 100 μm, and then mixed to obtain an industrial solid waste mixture;
[0014] Step 2: Prepare sodium hydroxide solution by adding the industrial solid waste mixture to the sodium hydroxide solution in the specified proportion;
[0015] Step 3: Transfer the mixed solid and liquid to a rotary autoclave for reaction, and the reaction time is 3-5 hours;
[0016] Step 4: After the reaction is complete, filter and dry the solid-liquid mixture to obtain solid waste-based nano-hydrated calcium silicate nucleating agent.
[0017] In step three, the heating rate is 5℃ / min, and the temperature is raised to 120-140℃.
[0018] In step three, the pressure is 0.5 MPa.
[0019] In step three, the rotation speed is 600 r / min.
[0020] Application of a solid waste-based nano-hydrated calcium silicate nucleating agent in low-heat cement.
[0021] An application of a solid waste-based nano-hydrated calcium silicate nucleating agent is described, which is prepared by adding 1-3% of the solid waste-based nano-hydrated calcium silicate nucleating agent by weight of low-heat cement as the main material, with a water-cement ratio of 0.5.
[0022] This invention synthesizes a solid waste-based nano-hydrated calcium silicate nucleating agent using carbide slag, yellow phosphorus slag, and sodium hydroxide solution as raw materials. Utilizing this nano-sized hydrated calcium silicate as a seed crystal in the early stages of low-heat cement hydration provides nucleation sites for the hydrated calcium silicate gel, a product of low-heat cement hydration. This lowers the nucleation barrier of the hydrated calcium silicate gel, promotes the hydration rate and early strength development of low-heat cement, and provides strong support for the later strength development of low-heat cement, effectively improving the problem of drying shrinkage cracking in low-heat cement. Detailed Implementation
[0023] The present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.
[0024] A solid waste-based nano-hydrated calcium silicate nucleating agent comprises, by weight, the following components: 10-30 parts of carbide slag, 20-45 parts of yellow phosphorus slag, and 400-2000 parts of sodium hydroxide solution.
[0025] This invention makes reasonable use of industrial solid waste such as carbide slag and yellow phosphorus slag to solve the safety and environmental problems caused by the shrinkage of low-heat cement in the complex environment of western plateau railways, and reduces production costs.
[0026] The main component of calcium carbide slag is calcium hydroxide, while the main components of yellow phosphorus slag are silicon dioxide and calcium oxide. Both calcium carbide slag and yellow phosphorus slag can react with water in an alkaline solution environment to form hydrated calcium silicate gel. Solid waste-based hydrated calcium silicate nucleating agents significantly improve the early strength of low-heat cement and reduce its drying shrinkage.
[0027] A method for preparing a solid waste-based nano-hydrated calcium silicate nucleating agent includes: mixing carbide slag and yellow phosphorus slag according to the above weight proportions and then grinding them to a particle size of less than 100 μm;
[0028] The specific surface area of carbide slag and yellow phosphorus slag is increased by grinding, which makes the synthesis reaction more rapid.
[0029] Prepare a sodium hydroxide solution with a pH of 11-12. Place the solid-liquid mixture into a rotary autoclave. The temperature in the autoclave is 120-140℃, the heating rate is 5℃ / min, the pressure in the autoclave is 0.5MPa, the rotation speed is 600r / min, and the reaction time is 3-5h.
[0030] The synthesis reaction needs to be carried out in an alkaline environment; by adjusting the pH value, the nucleating agent produced will be more effective. The synthesis reaction also requires heating; rotating and stirring are used to ensure a more complete synthesis.
[0031] After the reaction is complete, filter the solution and dry it at 60°C to obtain solid waste-based nano-hydrated calcium silicate nucleating agent.
[0032] The solid waste-based nano-hydrated calcium silicate nucleating agent prepared by this invention can improve the early compressive strength of low-heat cement and reduce its drying shrinkage rate. This invention efficiently and rationally utilizes solid wastes such as carbide slag and yellow phosphorus slag, improving the early strength of low-heat cement and significantly reducing drying shrinkage rate through nano-hydrated calcium silicate. Simultaneously, it transforms calcium hydroxide in carbide slag and silica in yellow phosphorus slag into valuable resources, reducing product production costs and enhancing the product's market competitiveness.
[0033] The calcium hydroxide content in carbide slag is ≥80%. The silica content in yellow phosphorus slag is ≥35%, and the calcium oxide content is ≥40%. This controls the ratio of effective components in carbide slag and yellow phosphorus slag.
[0034] Sodium hydroxide solution has a pH of 11-12, providing an alkaline environment.
[0035] Calcium carbide slag is rich in calcium hydroxide and can be used as a calcareous raw material, while yellow phosphorus slag contains a relatively high amount of silica and can be used as a siliceous raw material. Calcium carbide slag and yellow phosphorus slag can undergo a pozzolanic reaction in alkaline solutions to generate nano-sized hydrated calcium silicate. When added to low-heat cement in a certain dosage, hydrated calcium silicate can act as additional nucleation sites for the cement hydration product, calcium silicate gel, significantly reducing the nucleation barrier and effectively promoting the cement hydration rate and early strength development. It also improves the drying shrinkage rate of low-heat cement to some extent.
[0036] The application of a solid waste-based nano-hydrated calcium silicate nucleating agent in low-heat cement involves using low-heat cement as the main material, adding the solid waste-based nano-hydrated calcium silicate nucleating agent at a ratio of 1-3% by mass of the main material, and then adding water at a water-cement ratio of 0.5.
[0037] The particle size of the solid waste-based nano-hydrated calcium silicate nucleating agent was determined using a laser particle size analyzer. The effect of the solid waste-based nano-hydrated calcium silicate nucleating agent on the 18h, 1d, 3d, 7d, and 28d mortar strength of low-heat cement was tested according to GB / T17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)". The effect of the solid waste-based nano-hydrated calcium silicate nucleating agent on the 3d and 7d hydration heat of low-heat cement was tested according to GB / T 12959-2008 "Determination of Heat of Hydration of Cement". The effect of the solid waste-based nano-hydrated calcium silicate nucleating agent on the 28d drying shrinkage rate of low-heat cement was tested according to JC / T 603-2004 "Test Method for Drying Shrinkage of Cement Mortar".
[0038] The particle sizes of the solid waste-based nano-hydrated calcium silicate nucleating agent prepared in the examples are shown in Table 1:
[0039] Table 1
[0040]
[0041] The particle sizes of the solid waste-based nano-hydrated calcium silicate nucleating agents prepared in different embodiments are shown in Table 1. All of them are below 200 nm, with the smallest particle size (149.7 nm) observed in the solid waste-based nano-hydrated calcium silicate nucleating agent prepared in Example 1. This indicates that the hydrated calcium silicate nucleating agents prepared using carbide slag and yellow phosphorus slag are all at the nanoscale, exhibiting small particle size and high particle size.
[0042] Example 1:
[0043] The solid waste-based nano-hydrated calcium silicate nucleating agent of this embodiment comprises the following components by weight: 10 parts of carbide slag, 20 parts of yellow phosphorus slag, and 450 parts of sodium hydroxide solution. The carbide slag and yellow phosphorus slag were mixed according to the above weight proportions and then ground to a particle size of less than 45 μm. After further grinding, a sodium hydroxide solution with a pH of 11 was prepared. The solid-liquid mixture was placed in a rotary autoclave. The autoclave temperature was 120℃, the heating rate was 5℃ / min, the pressure was 0.5 MPa, the rotation speed was 600 r / min, and the reaction time was 3 h. After the reaction, the mixture was filtered and dried at 60℃ to obtain the solid waste-based nano-hydrated calcium silicate nucleating agent. It was added to low-heat cement at a dosage of 1% and tested according to the standards "Test Method for Strength of Cement Mortar (ISO Method)," "Determination of Heat of Hydration of Cement," and "Test Method for Drying Shrinkage of Cement Mortar." The results are shown in Table 2.
[0044] Example 2:
[0045] The solid waste-based nano-hydrated calcium silicate nucleating agent of this embodiment comprises the following components by weight: 12 parts of carbide slag, 25 parts of yellow phosphorus slag, and 620 parts of sodium hydroxide solution. The carbide slag and yellow phosphorus slag were mixed according to the above weight proportions and then ground to a particle size of less than 50 μm. After further grinding, a sodium hydroxide solution with a pH of 11 was prepared. The solid-liquid mixture was placed in a rotary autoclave. The autoclave temperature was 125℃, the heating rate was 5℃ / min, the pressure was 0.5 MPa, the rotation speed was 600 r / min, and the reaction time was 3 h. After the reaction, the mixture was filtered and dried at 60℃ to obtain the solid waste-based nano-hydrated calcium silicate nucleating agent. It was added to low-heat cement at a dosage of 1% and tested according to the standards "Test Method for Strength of Cement Mortar (ISO Method)," "Determination of Heat of Hydration of Cement," and "Test Method for Drying Shrinkage of Cement Mortar." The results are shown in Table 2.
[0046] Example 3:
[0047] The solid waste-based nano-hydrated calcium silicate nucleating agent of this embodiment comprises the following components by weight: 15 parts of carbide slag, 27 parts of yellow phosphorus slag, and 870 parts of sodium hydroxide solution. The carbide slag and yellow phosphorus slag were mixed according to the above weight proportions and then ground to a particle size of less than 55 μm. After further grinding, a sodium hydroxide solution with a pH of 11 was prepared. The solid-liquid mixture was placed in a rotary autoclave. The autoclave temperature was 130℃, the heating rate was 5℃ / min, the pressure was 0.5 MPa, the rotation speed was 600 r / min, and the reaction time was 4 h. After the reaction, the mixture was filtered and dried at 60℃ to obtain the solid waste-based nano-hydrated calcium silicate nucleating agent. It was added to low-heat cement at a dosage of 1% and tested according to the standards "Test Method for Strength of Cement Mortar (ISO Method)," "Determination of Heat of Hydration of Cement," and "Test Method for Dry Shrinkage of Cement Mortar." The results are shown in Table 2.
[0048] Example 4:
[0049] The solid waste-based nano-hydrated calcium silicate nucleating agent of this embodiment comprises the following components by weight: 13 parts of carbide slag, 28 parts of yellow phosphorus slag, and 760 parts of sodium hydroxide solution. The carbide slag and yellow phosphorus slag were mixed according to the above weight proportions and then ground to a particle size of less than 55 μm. After further grinding, a sodium hydroxide solution with a pH of 11 was prepared. The solid-liquid mixture was placed in a rotary autoclave. The autoclave temperature was 130℃, the heating rate was 5℃ / min, the pressure was 0.5 MPa, the rotation speed was 600 r / min, and the reaction time was 4 h. After the reaction, the mixture was filtered and dried at 60℃ to obtain the solid waste-based nano-hydrated calcium silicate nucleating agent. It was added to low-heat cement at a dosage of 1.5% and tested according to the standards "Test Method for Strength of Cement Mortar (ISO Method)," "Determination of Heat of Hydration of Cement," and "Test Method for Drying Shrinkage of Cement Mortar." The results are shown in Table 2.
[0050] Example 5:
[0051] The solid waste-based nano-hydrated calcium silicate nucleating agent of this embodiment comprises the following components by weight: 18 parts of carbide slag, 31 parts of yellow phosphorus slag, and 980 parts of sodium hydroxide solution. The carbide slag and yellow phosphorus slag were mixed according to the above weight proportions and then ground to a particle size of less than 60 μm. After further grinding, a sodium hydroxide solution with a pH of 11 was prepared. The solid-liquid mixture was placed in a rotary autoclave. The autoclave temperature was 135℃, the heating rate was 5℃ / min, the pressure was 0.5 MPa, the rotation speed was 600 r / min, and the reaction time was 5 h. After the reaction, the mixture was filtered and dried at 60℃ to obtain the solid waste-based nano-hydrated calcium silicate nucleating agent. It was added to low-heat cement at a dosage of 2% and tested according to the standards "Test Method for Strength of Cement Mortar (ISO Method)," "Determination of Heat of Hydration of Cement," and "Test Method for Drying Shrinkage of Cement Mortar." The results are shown in Table 2.
[0052] Example 6:
[0053] The solid waste-based nano-hydrated calcium silicate nucleating agent of this embodiment comprises the following components by weight: 30 parts of carbide slag, 42 parts of yellow phosphorus slag, and 1800 parts of sodium hydroxide solution. The carbide slag and yellow phosphorus slag were mixed according to the above weight proportions and then ground to a particle size of less than 60 μm. After further grinding, a sodium hydroxide solution with a pH of 11 was prepared. The solid-liquid mixture was placed in a rotary autoclave. The autoclave temperature was 140℃, the heating rate was 5℃ / min, the pressure was 0.5 MPa, the rotation speed was 600 r / min, and the reaction time was 5 h. After the reaction, the mixture was filtered and dried at 60℃ to obtain the solid waste-based nano-hydrated calcium silicate nucleating agent. It was added to low-heat cement at a dosage of 2% and tested according to the standards "Test Method for Strength of Cement Mortar (ISO Method)," "Determination of Heat of Hydration of Cement," and "Test Method for Dry Shrinkage of Cement Mortar." The results are shown in Table 2.
[0054] Table 2
[0055]
[0056] As shown in Table 2, the low-heat cement in the blank group without the addition of solid waste-based nano-hydrated calcium silicate nucleating agent had relatively low compressive strength, low heat of hydration, and high drying shrinkage rate (0.09%). The solid waste-based nano-hydrated calcium silicate nucleating agent, while improving the early and later strength of low-heat cement, can also enhance the cement stone's resistance to drying shrinkage and mitigate early structural defects caused by drying shrinkage.
[0057] The particle size of the solid waste-based nano-hydrated calcium silicate nucleating agent prepared in Example 7 is shown in Table 3:
[0058] Table 3
[0059]
[0060] The solid waste-based nano-hydrated calcium silicate nucleating agent prepared in Example 7 has a particle size of 125.7 nm, shows no agglomeration, has a uniform particle distribution, and high dispersibility.
[0061] Example 7:
[0062] The solid waste-based nano-hydrated calcium silicate nucleating agent of this embodiment comprises the following components by weight: 16 parts of carbide slag, 38 parts of yellow phosphorus slag, and 1600 parts of sodium hydroxide solution. The carbide slag and yellow phosphorus slag are mixed according to the above weight proportions and then ground to a particle size of less than 40 μm. After fine grinding, a sodium hydroxide solution with a pH of 11 is prepared. The solid-liquid mixture is placed in a rotary autoclave. The autoclave temperature is 125℃, the heating rate is 5℃ / min, the autoclave pressure is 0.5 MPa, the rotation speed is 600 r / min, and the reaction time is 3 h. After the reaction, the mixture is filtered and dried at 60℃ to obtain the solid waste-based nano-hydrated calcium silicate nucleating agent. It is added to low-heat cement at a dosage of 1%, and tested according to the standards "Test Method for Strength of Cement Mortar (ISO Method)," "Determination of Heat of Hydration of Cement," and "Test Method for Drying Shrinkage of Cement Mortar." The results are shown in Table 4.
[0063] Table 4
[0064]
[0065] As shown in Table 4, the prepared waste-based nano-hydrated calcium silicate nucleating agent significantly improved the early and later strength of low-heat cement, slightly increased the hydration heat release of low-heat cement, and greatly reduced the 28-day drying shrinkage rate of low-heat cement. This is because the hydrated calcium silicate seeds in the nucleating agent can provide nucleation sites for the hydrated calcium silicate gel, a hydration product of low-heat cement, reducing the nucleation barrier of the hydrated calcium silicate gel, promoting the hydration rate and early strength development of low-heat cement, and providing a strong guarantee for the later strength development of low-heat cement, effectively improving the problem of drying shrinkage cracking in low-heat cement. The synthesis of solid waste-based nano-hydrated calcium silicate nucleating agent provides a new approach for the future large-scale utilization of industrial solid waste for the preparation of new building materials, with good social and economic benefits.
[0066] This invention addresses the industrial solid waste generated by enterprises, specifically carbide slag and yellow phosphorus slag. It utilizes these materials to synthesize nano-sized hydrated calcium silicate nucleating agents, not only turning waste into treasure and conserving limited mineral resources, but also helping to solve the environmental pollution and land occupation problems caused by industrial solid waste from the chlor-alkali and phosphorus chemical industries. This method can dispose of large quantities of carbide slag and yellow phosphorus slag annually, producing high-quality solid waste-based nano-hydrated calcium silicate nucleating agents, which can then be transformed into economical and practical new building materials, yielding significant economic and social benefits. Furthermore, it expands the application pathways of carbide slag and yellow phosphorus slag, which is of great importance to the national utilization of solid waste resources.
[0067] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and changes to some of the technical features without creative effort, and all such substitutions and changes are within the protection scope of this invention.
Claims
1. A method for preparing a solid waste-based nano-hydrated calcium silicate nucleating agent, characterized in that, It is prepared from the following components in parts by weight: 10-30 parts of carbide slag, 20-45 parts of yellow phosphorus slag, and 400-2000 parts of sodium hydroxide solution; The calcium hydroxide content in the carbide slag is ≥80%; The yellow phosphorus slag contains ≥35% silicon dioxide and ≥40% calcium oxide. The pH value of the sodium hydroxide solution is 11-12; The preparation method includes the following steps: Step 1: The carbide slag and yellow phosphorus slag are mixed according to the weight proportions and then ground to a particle size of less than 100 μm, and then mixed to obtain an industrial solid waste mixture; Step 2: Prepare sodium hydroxide solution by adding the industrial solid waste mixture to the sodium hydroxide solution in the specified proportion; Step 3: Transfer the mixed solid and liquid to a rotary autoclave for reaction, and the reaction time is 3-5 hours; Step 4: After the reaction is complete, filter and dry the solid-liquid mixture to obtain solid waste-based nano-hydrated calcium silicate nucleating agent; In step three, the heating rate is 5℃ / min, and the temperature is raised to 120-140℃; In step three, the pressure is 0.5 MPa.
2. The preparation method of a solid waste-based nano-hydrated calcium silicate nucleating agent according to claim 1, characterized in that, In step three, the rotation speed is 600 r / min.
3. A solid waste-based nano-hydrated calcium silicate nucleating agent prepared by the preparation method of the solid waste-based nano-hydrated calcium silicate nucleating agent according to claim 1 or 2.
4. The application of the solid waste-based nano-hydrated calcium silicate nucleating agent of claim 3 in low-heat cement.