Method for producing a dolomite composite

Abstract

The application discloses a preparation method of dolomite composite material, which comprises the following steps: uniformly mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano silicon dioxide and long-chain fatty acid, so as to obtain the target product, the dolomite composite material. The dolomite composite material can be used as an external additive of concrete, has the functions of anti-cracking, anti-permeation and shrinkage compensation, effectively improves the compactness of the concrete, compensates the shrinkage of the concrete, and thus improves the anti-permeation and anti-cracking performances.

Description

Technical Field

[0001] This invention relates to the field of dolomite composite materials. More specifically, this invention relates to a method for preparing dolomite composite materials. Background Technology

[0002] During the hardening process after pouring, concrete almost universally undergoes some degree of shrinkage in the early stages. This can lead to cracks in the hardened concrete. These cracks not only affect the structural safety of the building but also reduce its long-term durability, posing unpredictable safety hazards to the entire project. Therefore, in actual concrete preparation, it is usually necessary to add certain admixtures or use special curing methods to overcome this defect.

[0003] Dolomite powder is a common and inexpensive industrial material. It is often added to concrete during production to improve its strength and hardness. However, this method of adding dolomite powder has limited effect on improving concrete performance and cannot effectively solve a key technical problem in concrete technology (shrinkage cracking). As a dolomite ore company, it can only sell raw dolomite powder at low prices. Therefore, it is worth considering developing a dolomite-based concrete admixture that can solve the shrinkage cracking problem in concrete and improve the technical and industrial value of dolomite. Summary of the Invention

[0004] To achieve these objectives and other advantages according to the present invention, a preferred embodiment of the present invention provides a method for preparing a dolomite composite material, comprising the following steps: uniformly mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano-silica, and long-chain fatty acid to obtain the target product, the dolomite composite material.

[0005] In one preferred embodiment, the raw materials used in the preparation method of the dolomite composite material are as follows (in parts by weight):

[0006]

[0007]

[0008] In one preferred embodiment, in the method for preparing the dolomite composite material, the specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg.

[0009] In one preferred embodiment, the quicklime used in the preparation method of the dolomite composite material is quicklime with a calcium oxide content greater than 85%.

[0010] In one preferred embodiment, in the preparation method of the dolomite composite material, the particle size of the modified dolomite powder is maintained at 10-20 μm, the moisture content is maintained at ≤0.8%, and the water absorption rate is maintained at ≥25%.

[0011] In one preferred embodiment, the long-chain fatty acid in the preparation method of the dolomite composite material is lauric acid.

[0012] In one preferred embodiment, the long-chain polyunsaturated fatty acid in the preparation method of the dolomite composite material is docosahexaenoic acid (DHA).

[0013] In one preferred embodiment, the modified dolomite powder is obtained by calcining dolomite powder at 950-1100℃ for 2-4 hours and then calcining it at 1200-1300℃ for 2-4 hours.

[0014] Calcination of dolomite is intended to improve its activity. However, if the calcination temperature exceeds 1300℃ or falls below 900℃, the hydration activity of the calcined dolomite will be low. Therefore, the calcination temperature must be controlled within the range of 900℃ above its complete decomposition temperature and 1460-1500℃ below its sintering temperature.

[0015] The present invention has at least the following beneficial effects: The dolomite composite material of the present invention uses dolomite as raw material and can be used as an external additive for concrete. It has the functions of crack resistance, impermeability, and shrinkage compensation, effectively improving the compactness of concrete and compensating for concrete shrinkage, thereby improving impermeability and crack resistance. By introducing polyether-siloxane copolymer, the surface tension of water between different particle components during concrete preparation is reduced, thereby reducing the shrinkage stress when the micropores of the particles absorb water, thus effectively controlling the early shrinkage of concrete.

[0016] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0018] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0019] Example 1

[0020] A method for preparing a dolomite composite material includes the following steps: mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano-silica, and long-chain fatty acid evenly to obtain the target product, the dolomite composite material.

[0021] The mixture contains 80 parts modified dolomite powder, 30 parts dehydrated phosphogypsum, 8 parts quicklime, 5 parts polyether-siloxane copolymer, 5 parts long-chain polyunsaturated fatty acids, 3 parts polypropylene glycol glycidyl ether, 3 parts nano silica, and 3 parts long-chain fatty acids.

[0022] The specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg. The quicklime is quicklime with a calcium oxide content greater than 85%. The modified dolomite powder has a particle size maintained at 10-20 μm, a moisture content maintained at ≤0.8%, and a water absorption rate maintained at ≥25%. The long-chain fatty acid is lauric acid. The long-chain polyunsaturated fatty acid is docosahexaenoic acid. The modified dolomite powder is obtained by calcining dolomite powder at 950℃ for 2 hours and then at 1200℃ for 2 hours.

[0023] Example 2

[0024] A method for preparing a dolomite composite material includes the following steps: mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano-silica, and long-chain fatty acid evenly to obtain the target product, the dolomite composite material.

[0025] The mixture contains 90 parts modified dolomite powder, 40 parts dehydrated phosphogypsum, 9 parts quicklime, 6 parts polyether-siloxane copolymer, 6 parts long-chain polyunsaturated fatty acids, 3 parts polypropylene glycol glycidyl ether, 3 parts nano silica, and 3 parts long-chain fatty acids.

[0026] The specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg. The quicklime is quicklime with a calcium oxide content greater than 85%. The modified dolomite powder has a particle size maintained at 10-20 μm, a moisture content maintained at ≤0.8%, and a water absorption rate maintained at ≥25%. The long-chain fatty acid is lauric acid. The long-chain polyunsaturated fatty acid is docosahexaenoic acid. The modified dolomite powder is obtained by calcining dolomite powder at 950℃ for 2 hours and then at 1200℃ for 2 hours.

[0027] Example 3

[0028] A method for preparing a dolomite composite material includes the following steps: mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano-silica, and long-chain fatty acid evenly to obtain the target product, the dolomite composite material.

[0029] The mixture contains 95 parts modified dolomite powder, 60 parts dehydrated phosphogypsum, 10 parts quicklime, 8 parts polyether-siloxane copolymer, 8 parts long-chain polyunsaturated fatty acids, 4 parts polypropylene glycol glycidyl ether, 4 parts nano silica, and 4 parts long-chain fatty acids.

[0030] The specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg. The quicklime is quicklime with a calcium oxide content greater than 85%. The modified dolomite powder has a particle size maintained at 10-20 μm, a moisture content maintained at ≤0.8%, and a water absorption rate maintained at ≥25%. The long-chain fatty acid is lauric acid. The long-chain polyunsaturated fatty acid is docosahexaenoic acid. The modified dolomite powder is obtained by calcining dolomite powder at 950℃ for 2 hours and then at 1200℃ for 2 hours.

[0031] Comparative Example 1

[0032] The difference between this comparative example and Example 1 is that the proportions of the raw materials in the formulation are different, while the remaining steps and components are the same as in Example 1.

[0033] A method for preparing a dolomite composite material includes the following steps: mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano-silica, and long-chain fatty acid evenly to obtain the target product, the dolomite composite material.

[0034] The mixture contains 80 parts modified dolomite powder, 30 parts dehydrated phosphogypsum, 8 parts quicklime, 10 parts polyether-siloxane copolymer, 10 parts long-chain polyunsaturated fatty acids, 3 parts polypropylene glycol glycidyl ether, 3 parts nano silica, and 3 parts long-chain fatty acids.

[0035] The specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg. The quicklime is quicklime with a calcium oxide content greater than 85%. The modified dolomite powder has a particle size maintained at 10-20 μm, a moisture content maintained at ≤0.8%, and a water absorption rate maintained at ≥25%. The long-chain fatty acid is lauric acid. The long-chain polyunsaturated fatty acid is docosahexaenoic acid. The modified dolomite powder is obtained by calcining dolomite powder at 950℃ for 2 hours and then at 1200℃ for 2 hours.

[0036] Comparative Example 2

[0037] The difference between this comparative example and Example 1 is that the proportion of raw materials in the formulation of this comparative example is different, while the remaining steps and components are the same as in Example 1.

[0038] A method for preparing a dolomite composite material includes the following steps: mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano-silica, and long-chain fatty acid evenly to obtain the target product, the dolomite composite material.

[0039] The mixture contains 80 parts modified dolomite powder, 30 parts dehydrated phosphogypsum, 8 parts quicklime, 5 parts polyether-siloxane copolymer, 5 parts long-chain polyunsaturated fatty acids, 8 parts polypropylene glycol glycidyl ether, 8 parts nano silica, and 8 parts long-chain fatty acids.

[0040] The specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg. The quicklime is quicklime with a calcium oxide content greater than 85%. The modified dolomite powder has a particle size maintained at 10-20 μm, a moisture content maintained at ≤0.8%, and a water absorption rate maintained at ≥25%. The long-chain fatty acid is lauric acid. The long-chain polyunsaturated fatty acid is docosahexaenoic acid. The modified dolomite powder is obtained by calcining dolomite powder at 950℃ for 2 hours and then at 1200℃ for 2 hours.

[0041] Comparative Example 3

[0042] The difference between this comparative example and Example 1 is that the proportion of raw materials in the formulation of this comparative example is different, while the remaining steps and components are the same as in Example 1.

[0043] A method for preparing a dolomite composite material includes the following steps: mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano-silica, and long-chain fatty acid evenly to obtain the target product, the dolomite composite material.

[0044] The mixture contains 120 parts modified dolomite powder, 30 parts dehydrated phosphogypsum, 8 parts quicklime, 5 parts polyether-siloxane copolymer, 1 part long-chain polyunsaturated fatty acid, 1 part polypropylene glycol glycidyl ether, 1 part nano silica, and 3 parts long-chain fatty acid.

[0045] The specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg. The quicklime is quicklime with a calcium oxide content greater than 85%. The modified dolomite powder has a particle size maintained at 10-20 μm, a moisture content maintained at ≤0.8%, and a water absorption rate maintained at ≥25%. The long-chain fatty acid is lauric acid. The long-chain polyunsaturated fatty acid is docosahexaenoic acid. The modified dolomite powder is obtained by calcining dolomite powder at 950℃ for 2 hours and then at 1200℃ for 2 hours.

[0046] Comparative Example 4

[0047] The difference between this comparative example and Example 1 is that the polyether-siloxane copolymer is not introduced in this comparative example, while the remaining steps and components are the same as in Example 1.

[0048] Comparative Example 5

[0049] The difference between this comparative example and Example 1 is that polypropylene glycol glycidyl ether is not introduced in this comparative example, while the remaining steps and components are the same as in Example 1.

[0050] Comparative Example 6

[0051] The difference between this comparative example and Example 1 is that long-chain fatty acids and long-chain polyunsaturated fatty acids are not introduced in this comparative example, while the remaining steps and components are the same as in Example 1.

[0052] The dolomite composite materials prepared in Examples 1-3 and Comparative Examples 1-6 were incorporated into ordinary concrete for performance testing. A blank comparative example was also included, in which no dolomite composite material was incorporated. The test results are shown in Table 1. The dolomite composite material dosage was 1.5% in all examples. Shrinkage rate was determined according to JC / T 2361-2016; the compressive strength and flexural strength of concrete were determined according to GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and the specimen size was the standard size specified in the standard.

[0053] Table 1

[0054]

[0055] As can be seen from the data in Table 1, compared with Comparative Examples 1-6 and the blank comparative example, the compressive strength, flexural strength and shrinkage rate of the concrete in Examples 1-3, which incorporate the dolomite composite material prepared by the method of the present invention, are greatly improved.

[0056] Compared to Comparative Example 4, which did not introduce polyether-siloxane copolymer, the concrete containing the composite material of Example 2 exhibited superior mechanical properties and shrinkage resistance. This is because the polyether-siloxane copolymer can reduce the surface tension of water between different particle components during concrete preparation, thereby reducing the shrinkage stress when the micropores of the particles absorb water, thus effectively controlling the early shrinkage of the concrete.

[0057] Compared to Comparative Example 5, which did not introduce polypropylene glycol glycidyl ether, the mechanical properties and shrinkage resistance of the concrete doped with the composite material of Example 2 were greatly improved. This is because the high molecular weight polypropylene glycol glycidyl ether acts as an adsorbent, which can interact and bridge with the aerogel in the concrete components in the later stage to form a network structure, making the concrete structure more stable. Dolomite particles and nano-silica particles enter the gaps in the network structure to fill them. The larger-diameter dolomite particles are used for initial filling, and then the smaller-diameter nano-particles are used for secondary filling. This can further improve the strength of the concrete structure and reduce the degree of early shrinkage of the concrete.

[0058] In this application, calcium oxide reacts with cement and water to form Ca(OH)2, resulting in expansion. The rapid expansion of calcium oxide can offset the shrinkage of concrete. However, calcium oxide suffers from excessively rapid hydration and uncontrollable expansion. Therefore, this application introduces long-chain fatty acids and long-chain polyunsaturated fatty acids to regulate the hydration of calcium oxide. The carboxylic acid groups of the long-chain polyunsaturated fatty acids form hydrogen bonds with the hydroxyl groups in the concrete, and the oxygen in the long-chain polyunsaturated fatty acids forms silicon-oxygen bonds with the silicon in the concrete components. Under the dual action of hydrogen bonds and silicon-oxygen bonds, the long-chain molecules can be well connected to the concrete surface. The strong hydrogen bonds between the two types of long-chain molecules form a network structure that can adhere to the surface of other components, encapsulating calcium oxide within it. This restrains and controls the hydration process of calcium oxide, achieving gradual release and thus gradually offsetting the shrinkage of the concrete. Expansion and shrinkage are almost synchronous. Therefore, compared to Comparative Example 6 without the introduction of long-chain fatty acids and long-chain polyunsaturated fatty acids, the concrete containing the composite material of Example 2 exhibits significantly improved shrinkage resistance and mechanical properties.

[0059] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for preparing a dolomite composite material, characterized in that, Includes the following steps: The target product, dolomite composite material, is obtained by uniformly mixing modified dolomite powder, dehydrated phosphogypsum, polyether-siloxane copolymer, long-chain polyunsaturated fatty acid, polypropylene glycol glycidyl ether, nano silica, and long-chain fatty acid. The raw materials used are as follows (in parts by weight): 80-95 parts of modified dolomite powder; 30-60 parts of dehydrated phosphogypsum; 8-10 parts quicklime; 5-8 parts of polyether-siloxane copolymer; 5-8 parts of long-chain polyunsaturated fatty acids; 3-4 parts of polypropylene glycol glycidyl ether; 3-4 parts of nano-silica; 3-4 parts of long-chain fatty acids; The long-chain fatty acid is lauric acid; The long-chain polyunsaturated fatty acid is docosahexaenoic acid; The modified dolomite powder is obtained by calcining dolomite powder at 950-1100℃ for 2-4 hours and then calcining it at 1200-1300℃ for 2-4 hours.

2. The method for preparing dolomite composite material according to claim 1, characterized in that, The specific surface area of ​​the dehydrated phosphogypsum is controlled to be greater than 500 m². 2 / kg.

3. The method for preparing dolomite composite material according to claim 1, characterized in that, The quicklime is quicklime with a calcium oxide content greater than 85%.

4. The method for preparing the dolomite composite material according to claim 1, characterized in that, The modified dolomite powder has a particle size of 10-20 μm, a moisture content of ≤0.8%, and a water absorption rate of ≥25%.

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