Gradient active mixed material, preparation method and application thereof

Abstract

The present application relates to the technical field of building materials, and discloses a gradient active admixture, a preparation method and application thereof. The preparation method comprises: preparing at least two first raw materials; the first raw material is obtained by adding a sodium hydroxide solution to dry shield drying soil and successively mixing, stirring, grinding and drying, and the content of sodium hydroxide in the sodium hydroxide solution added to each first raw material is different from each other; according to a preset ratio, each first raw material is mixed to obtain a second raw material; the second raw material is calcined in an environment of 500-680°C until the surface sodium element is completely reacted, and after the calcination is completed, it is rapidly cooled to obtain a clinker; the clinker is ground to obtain a gradient active admixture. The embodiments of the present application can stimulate the potential hydraulic hardness of the gradient active admixture and improve the early activity of the gradient active admixture.

Description

Technical Field

[0001] The present application relates to the technical field of building materials, and in particular to a gradient active mixed material, a preparation method thereof and an application thereof. Background Art

[0002] Admixtures refer to artificial or natural mineral materials that are added to the mill together with clinker and gypsum when grinding cement to improve cement properties, adjust cement grade, and increase cement production.

[0003] In the related art, shield-dried soil can be used to prepare mixed materials, specifically, shield-dried soil is used as raw material, an appropriate amount of alkali is added, and the mixed material is prepared by calcination. However, when shield-dried soil is used to prepare mixed materials, the activity index of the prepared mixed materials is very easy to fluctuate, and it is difficult to always maintain a good potential hydraulic hardness. The potential hydraulic hardness is slow to play, especially the mechanical properties of the early hardened slurry are poor. Summary of the invention

[0004] The purpose of the present application is to provide a gradient active admixture, a preparation method and application thereof, which can stimulate the potential hydraulic hardness of the admixture and improve the early activity of the admixture.

[0005] The present application provides a method for preparing a gradient active mixed material, comprising:

[0006] preparing at least two first raw materials; the first raw materials are obtained by adding sodium hydroxide solution to dry shield-dried soil and then mixing, stirring, grinding and drying in sequence, and the sodium hydroxide content in the sodium hydroxide solution added to each of the first raw materials is different from each other;

[0007] Mixing the first raw materials according to a preset ratio to obtain a second raw material;

[0008] The second raw material is calcined in an environment of 500-680° C. until the surface sodium element is completely reacted, and then rapidly cooled after the calcination to obtain clinker;

[0009] The clinker is ground to obtain a gradient active mixed material.

[0010] Preferably, the mass of the sodium hydroxide solution is 15-25wt% of the mass of the shield drying soil, one mass of the sodium hydroxide added to the sodium hydroxide solution by the first raw material is 0.01-1.0wt% of the mass of the shield drying soil, and another mass of the sodium hydroxide added to the sodium hydroxide solution by the first raw material is 1.0-12wt% of the mass of the shield drying soil.

[0011] Preferably, the mixing ratio of the first raw material with the highest sodium hydroxide content is 5-50%.

[0012] Preferably, the specific surface area of ​​the first raw material is 360-460 m 2 / kg.

[0013] Preferably, the specific surface area of ​​the gradient active mixed material is 360-460 m 2 / kg.

[0014] Preferably, the mass of the sodium hydroxide in the second raw material is 0.06-6.5wt% of the mass of the shield drying soil.

[0015] Preferably, the duration of calcining the second raw material is 20-50 minutes.

[0016] Preferably, the rapid cooling is water cooling, and drying is performed after the rapid cooling, and the water temperature of the rapid cooling is not higher than 30°C.

[0017] The embodiments of the present application also provide a gradient active mixed material prepared by the method for preparing the gradient active mixed material as described above.

[0018] The embodiments of the present application also provide the use of the gradient active admixture as described above in the preparation of cement or concrete.

[0019] Beneficial effects of this application:

[0020] (1) A method for preparing a gradient active admixture from shield-dried soil is provided, wherein a sodium hydroxide distribution with a concentration gradient is formed on the surface of the shield-dried soil, and then low-temperature rapid calcination is performed with the help of the sodium element's fluxing, lattice destruction, and liquid phase generation, so that shield-dried soil with different sodium hydroxide concentrations produces different defect structures during the alkali calcination and migration process. Thus, shield-dried soil with different activities can produce a synergistic effect during the hydration process and continuously improve the slurry structure. By adjusting the preparation process parameters, the potential hydraulic hardness of shield-dried soil at different ages can be regulated and matched to meet the performance requirements of industries such as silicate cement and high-strength concrete for admixtures.

[0021] (2) The shield drying soil with a sodium hydroxide concentration gradient on the calcined surface is used to significantly increase the amount of alkali in the shield drying soil. Not only is the shield drying soil deeply optimized and modified with the help of high alkali, and has extremely high potential hydraulic hardness, but the unreacted sodium hydroxide in the high-alkali shield drying soil will migrate to the low-alkali shield drying soil during the calcination process. The migrated alkali not only modifies and calcines the shield drying soil well, making the shield drying soil have gradient activity, but also effectively reduces the final residual alkali content, making the mixed material extremely active both in the early and late stages. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] It should be noted that the terms "first", "second" and the like in the specification and claims are used to distinguish similar objects, but are not used to describe a specific order or sequence.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0025] The present application provides a method for preparing a gradient active mixed material, comprising:

[0026] At least two first raw materials are prepared; the first raw materials are obtained by adding sodium hydroxide solution to dry shield-dried soil and then mixing, stirring, grinding and drying in sequence, and the contents of sodium hydroxide in the sodium hydroxide solutions added to the first raw materials are different from each other;

[0027] Mixing the first raw materials according to a preset ratio to obtain a second raw material;

[0028] The second raw material is calcined in an environment of 500-680°C until the surface sodium element is completely reacted, and then rapidly cooled after the calcination to obtain clinker;

[0029] The clinker is ground to obtain a gradient active mixed material.

[0030] Preferably, the mass of the sodium hydroxide solution is 15-25wt% of the mass of the shield drying soil, the mass of the sodium hydroxide added to the sodium hydroxide solution of the first raw material is 0.01-1.0wt% of the mass of the shield drying soil, and the mass of the sodium hydroxide added to the sodium hydroxide solution of the other first raw material is 1.0-12wt% of the mass of the shield drying soil.

[0031] Preferably, the mixing ratio of the first raw material with the highest sodium hydroxide content is 5-50%.

[0032] Preferably, the specific surface area of ​​the first raw material is 360-460 m 2 / kg.

[0033] Preferably, the specific surface area of ​​the gradient active mixed material is 360-460 m 2 / kg.

[0034] Preferably, the mass of sodium hydroxide in the second raw material is 0.06-6.5wt% of the mass of the shield drying soil.

[0035] Preferably, the duration of calcining the second raw material is 20-50 minutes.

[0036] Preferably, the rapid cooling is water cooling, and drying is performed after the rapid cooling, and the water temperature of the rapid cooling is not higher than 30°C.

[0037] The present application is further described below in conjunction with specific embodiments.

[0038] In the following embodiments and comparative examples, except comparative example 3, two portions of the first raw material are prepared.

[0039] In the following embodiments and comparative examples, the shield drying soil is mixed with 55.4wt% silicon dioxide, 27.8wt% aluminum oxide, 6.3wt% ferrosoferric oxide, 3.2wt% potassium oxide, 2.1wt% magnesium oxide, 1.3wt% titanium dioxide, 2.0wt% calcium oxide, 1.3wt% sodium oxide and 0.6wt% impurities.

[0040] Example 1

[0041] Take 10g of sodium hydroxide and 200.0g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix it and grind it to a specific surface area of ​​400 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​400m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0042] The mixing ratio of the first raw material A and B is set to 50:50. 500g of the first raw material A and 500g of the first raw material B are mixed evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 450°C and calcined for 50 minutes until the sodium element on the surface of the shield drying soil is completely consumed to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​400m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for concrete admixture performance testing is used to test the admixture activity index according to GB / T12957-2005 standard. Referring to Table 1, the admixture activity indexes at 7d and 28d are both high.

[0043] Example 2

[0044] Take 50g of sodium hydroxide and 200.0g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix and grind to a specific surface area of ​​360 m 2 / kg, and after drying, a powdered first raw material A is obtained. 5g of sodium hydroxide and 200g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​360m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0045] The mixing ratio of the first raw material A and B is set to 20:80. Take 200g of the first raw material A and 800g of the first raw material B and mix them evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 550℃ and calcined for 30 minutes until the sodium element on the surface of the shield drying soil is completely consumed to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​360m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for concrete admixture performance testing is used to test the admixture activity index according to GB / T12957-2005 standard. Refer to Table 1, the admixture 7d and 28d activity indexes are both very high.

[0046] Example 3

[0047] Take 120g of sodium hydroxide and 250.0g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix it and grind it to a specific surface area of ​​460 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​460m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0048] The mixing ratio of the first raw material A and B is set to 5:95. Take 50g of the first raw material A and 950g of the first raw material B and mix them evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 650℃ and calcined for 20 minutes until the sodium element on the surface of the shield drying soil is completely consumed to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​460m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for concrete admixture performance testing is used to test the admixture activity index according to GB / T12957-2005 standard. Referring to Table 1, the admixture activity indexes at 7d and 28d are both high.

[0049] Example 4

[0050] Take 50g of sodium hydroxide and 200g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix it and grind it to a specific surface area of ​​440 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​440m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0051] The mixing ratio of the first raw material A and B is set to 15:85. 150g of the first raw material A and 850g of the first raw material B are mixed evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 650℃ and calcined for 40 minutes until the sodium element on the surface of the shield drying soil is completely consumed to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​440m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for concrete admixture performance testing is used to test the admixture activity index according to GB / T12957-2005 standard. Referring to Table 1, the 7-day activity index of the admixture is as high as 98.9%, close to the benchmark cement, and the 28-day activity index is as high as 100.2%, exceeding the benchmark cement.

[0052] Comparative Example 1

[0053] Take 50g of sodium hydroxide and 200g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix and grind to a specific surface area of ​​450 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​440m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0054] The mixing ratio of the first raw material A and B is set to 80:20. 800g of the first raw material A and 200g of the first raw material B are mixed evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 500°C and calcined for 30 minutes until the sodium element on the surface of the shield drying soil is completely consumed to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​450m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for testing the performance of concrete admixtures is used to test the activity index of the admixture according to GB / T12957-2005 standard. Refer to Table 1, and the activity index is unqualified (<65%).

[0055] Comparative Example 2

[0056] Take 300g of sodium hydroxide and 250g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix it and grind it to a specific surface area of ​​420 m 2 / kg, and dried to obtain the first raw material A in powder form. Take 0.5g of sodium hydroxide and 150g of water to prepare a sodium hydroxide solution, add it to 1000g of shield-dried soil, mix it and grind it to a specific surface area of ​​420m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0057] The mixing ratio of the first raw material A and B is set to 25:75. Take 250g of the first raw material A and 750g of the first raw material B and mix them evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 550℃ and calcined for 30 minutes until the sodium element on the surface of the shield drying soil is completely consumed to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​420m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for concrete admixture performance testing is used to test the admixture activity index according to GB / T12957-2005 standard. Refer to Table 1, the activity index is poor, only 65.3% at 7d and only 66.5% at 28d.

[0058] Comparative Example 3

[0059] Take 0.5g of sodium hydroxide and 150g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix and grind to a specific surface area of ​​440 m 2 / kg, dried to obtain powdered raw material and calcined in a high-temperature furnace at 650℃ for 30 minutes. The clinker was cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​440m 2 / kg, and the mixed material was obtained. The benchmark cement used for testing the performance of concrete admixtures was used to test the activity index of the mixed material according to the GB / T12957-2005 standard. Referring to Table 1, the 7d activity index of the mixed material was not high, only 74.6%, and the 28d activity index was 80.1%.

[0060] Comparative Example 4

[0061] Take 50g of sodium hydroxide and 200g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix and grind to a specific surface area of ​​450 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​440m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0062] The mixing ratio of the first raw material A and B is set to 15:85. 150g of the first raw material A and 850g of the first raw material B are mixed evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 300°C and calcined for 50 minutes. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​450m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for testing the performance of concrete admixtures is used to test the activity index of the admixture according to GB / T12957-2005 standard. Refer to Table 1, and the activity index is unqualified (<65%).

[0063] Comparative Example 5

[0064] Take 50g of sodium hydroxide and 200g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix and grind to a specific surface area of ​​450 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​440m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0065] The mixing ratio of the first raw material A and B is set to 15:85. 150g of the first raw material A and 850g of the first raw material B are mixed evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 600℃ and calcined for 5 minutes to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​450m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for testing the performance of concrete admixtures is used to test the activity index of the admixture according to GB / T12957-2005 standard. Refer to Table 1, and the activity index is unqualified (<65%).

[0066] Comparative Example 6

[0067] Take 50g of sodium hydroxide and 200g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix and grind to a specific surface area of ​​450 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​440m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0068] The mixing ratio of the first raw material A and B is set to 15:85. Take 150g of the first raw material A and 850g of the first raw material B and mix them evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 650℃ and calcined for 100 minutes to ensure that the sodium element on the surface of the shield drying soil is completely reacted to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​450m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for testing the performance of concrete admixtures is used to test the activity index of the admixture according to GB / T12957-2005 standard. Referring to Table 1, the 7d and 28d activity indexes are significantly reduced compared with those of Example 4, and both are less than 85%.

[0069] Comparative Example 7

[0070] Take 50g of sodium hydroxide and 200g of water to make a sodium hydroxide solution, add it to 1000g of shield drying soil, mix and grind to a specific surface area of ​​450 m 2 / kg, and after drying, a powdered first raw material A is obtained. 0.5g of sodium hydroxide and 150g of water are taken to prepare a sodium hydroxide solution, which is added to 1000g of shield-dried soil, mixed and ground to a specific surface area of ​​440m 2 / kg, and after drying, a powdery first raw material B is obtained.

[0071] The mixing ratio of the first raw material A and B is set to 15:85. 150g of the first raw material A and 850g of the first raw material B are mixed evenly to obtain the second raw material. The second raw material is placed in a high-temperature furnace at 800°C and calcined for 40 minutes to ensure that the sodium element on the surface of the shield drying soil is fully reacted to obtain clinker. The clinker is cooled to room temperature by water cooling and dried, and ground to a specific surface area of ​​450m 2 / kg, a gradient active admixture is obtained. The benchmark cement used for testing the performance of concrete admixtures is used to test the activity index of the admixture according to GB / T12957-2005 standard. Referring to Table 1, the 7d and 28d activity indexes are significantly reduced compared with those of Example 4, and both are less than 80.0%.

[0072] Table 1

[0073]

[0074] As can be seen from Examples 1-4, after low-temperature rapid calcination of shield drying soil with a sodium hydroxide concentration gradient, the high-temperature migration and consumption of sodium hydroxide prompt it to produce a differential defective structure, and shield drying soils of different activities can produce a synergistic effect during the hydration process, generating secondary hydration products of varying amounts at different ages (7d, 28d, etc.), and continuously, effectively, and stably improving the cement hardening slurry structure. For example, in the designed embodiment 4, the 7d activity index of the hardened slurry is as high as 98.9%, and the 28d strength even exceeds the benchmark cement. Further, by adjusting the process parameters (sodium hydroxide concentration / first raw material ratio / calcination system, etc.), the potential hydraulic depth regulation and matching of shield drying soil at different ages (7d, 28d, etc.) can be achieved, meeting the performance requirements of industries such as silicate cement and concrete for gradient active mixed materials. As can be seen from Comparative Example 1, the high-alkali shield drying soil dosage in the second raw material is too high, resulting in a large amount of residual alkali deteriorating slurry structure, and the activity index is unqualified. It can be seen from Comparative Example 2 that if the concentration of sodium hydroxide in the high-alkali shield drying soil in the first raw material is too high, there will be an excess of alkali locally, which is not conducive to the development of the slurry structure, and the activity index barely meets the standard. From Comparative Example 3, it can be seen that the 28d activity index (81.4%) of the shield drying soil calcined with a very small amount of alkali (0.05%) is acceptable, but the 7d activity index is low, only 74.6%, which confirms that a small amount of alkali cannot improve the early activity of the hardened slurry. From Comparative Examples 4 and 5, it can be seen that lower calcination temperatures or shorter calcination times cannot effectively cause shield drying soil modification reactions, and unreacted alkali will cause the slurry performance to drop sharply, and the activity index is unqualified. From Comparative Examples 6 and 7, it can be seen that increasing the calcination temperature or extending the calcination time cannot further improve the activity index, and even a downward trend appears. The reason is that the inert minerals formed in the shield drying soil hinder the secondary hydration reaction.

[0075] The exemplary embodiments of the present disclosure are specifically shown and described above. It should be understood that the present disclosure is not limited to the configuration or implementation method described herein; on the contrary, the present disclosure is intended to cover various modifications and equivalent configurations contained within the spirit and scope of the appended claims.

Claims

1. A method for preparing a gradient active mixed material, characterized in that: include: preparing at least two first raw meals; The first raw material is obtained by adding sodium hydroxide solution to dry shield-dried soil and mixing, stirring, grinding and drying in sequence. The content of sodium hydroxide in the sodium hydroxide solution added to each of the first raw materials is different. The mass of the sodium hydroxide solution is 15-25wt% of the mass of the shield-dried soil. The mass of sodium hydroxide added to the sodium hydroxide solution of one of the first raw materials is 0.01-1.0wt% of the mass of the shield-dried soil. The mass of sodium hydroxide added to the sodium hydroxide solution of the other first raw material is 1.0-12wt% of the mass of the shield-dried soil. The first raw materials are mixed according to a preset ratio to obtain a second raw material; the mixing ratio of the first raw material with the highest sodium hydroxide content is 5-50%; calcining the second raw material in an environment of 500-680° C. until the surface sodium element is completely reacted, and then rapidly cooling after the calcination to obtain clinker; the calcination time of the second raw material is 20-50 minutes; The clinker is ground to obtain a gradient active mixed material.

2. The method for preparing the gradient active mixed material according to claim 1, characterized in that: The specific surface area of ​​the first raw material is 360-460 m 2 / kg.

3. The method for preparing the gradient active mixed material according to claim 1, characterized in that: The specific surface area of ​​the gradient active mixed material is 360-460 m 2 / kg.

4. The method for preparing the gradient active mixed material according to claim 1, characterized in that: The mass of the sodium hydroxide in the second raw material is 0.06-6.5wt% of the mass of the shield drying soil.

5. The method for preparing the gradient active mixed material according to claim 1, characterized in that: The rapid cooling is water cooling, and drying is performed after the rapid cooling is completed. The water temperature of the rapid cooling is not higher than 30°C.

6. A gradient active mixed material prepared by the method for preparing a gradient active mixed material according to any one of claims 1 to 5.

7. Use of the gradient active admixture as claimed in claim 6 in the preparation of cement or concrete.

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