Concrete for neutron radiation protection and method for producing same

Abstract

The application provides a neutron radiation protection concrete and a preparation method thereof. The neutron radiation protection concrete comprises the following raw materials: serpentine aggregate, a gel material, a water reducing agent, a borate-containing aqueous solution, and mixing water. The gel material comprises cement. The neutron radiation protection concrete provided by the application has excellent neutron shielding effect and mechanical properties.

Description

Technical Field

[0001] This application relates to the field of concrete technology, and in particular to a neutron radiation-protective concrete and its preparation method. Background Technology

[0002] Due to the need for miniaturized reactor structures, neutron shielding materials are required near the reactor for radioactive containment. In applications near the reactor, ambient temperatures exceed 300°C. Traditional polymer shielding materials are no longer suitable. Radiation-shielding concrete, with its low cost and superior structural performance compared to polymer shielding materials, is a potentially valuable option. However, current radiation-shielding concrete still suffers from poor mechanical properties and neutron shielding effectiveness in high-temperature environments (above 300°C). Summary of the Invention

[0003] Based on this, this application provides a neutron radiation protection concrete with excellent mechanical properties and neutron shielding effect, and a method for preparing the same.

[0004] The first aspect of this application provides a neutron radiation-protective concrete, comprising the following raw materials: serpentine aggregate, gel material, water-reducing agent, aqueous solution containing borate, and mixing water, wherein the gel material comprises cement.

[0005] In some embodiments of this application, the weight parts of each component in the raw material are as follows: serpentine aggregate, 1500-1800 parts; gel material, 400-520 parts; water-reducing agent, 30-40 parts; aqueous solution containing borate, 25-35 parts; and mixing water, 140-180 parts.

[0006] In some embodiments of this application, at least one of the following conditions is met:

[0007] (1) The serpentine aggregate does not contain asbestos fibers;

[0008] (2) The concentration of borate in the aqueous solution containing borate is 0.01 g / mL to 0.05 g / mL;

[0009] (3) The cement in the gel material is 280 to 360 parts by weight;

[0010] (4) The cement includes silicate cement;

[0011] Optionally, the strength grade of the silicate cement is ≥52.5.

[0012] In some embodiments of this application, the gel material further includes mineral powder and fly ash;

[0013] Optionally, the weight percentage of the mineral powder in the gel material is 60 to 80 parts;

[0014] Optionally, the fly ash in the gel material is 60 to 80 parts by weight;

[0015] Optionally, the average particle size of the mineral powder is 50 μm to 100 μm;

[0016] Optionally, the average particle size of the fly ash is 50 μm to 100 μm.

[0017] In some embodiments of this application, at least one of the following conditions is met:

[0018] (1) The mineral powder contains CaO, SiO2, Al2O3 and MgO;

[0019] Optionally, in the mineral powder, the mass percentage of CaO is 30%~42%, the mass percentage of SiO2 is 35%~38%, the mass percentage of Al2O3 is 10%~18%, and the mass percentage of MgO is 5%~14%.

[0020] (2) The fly ash contains SiO2, Al2O3, Fe2O3 and CaO;

[0021] Optionally, in the fly ash, the mass percentage of SiO2 is 34%~51%, the mass percentage of Al2O3 is 17%~30%, the mass percentage of CaO is 1%~10%, and the mass percentage of Fe2O3 is 5%~15%.

[0022] In some embodiments of this application, the serpentine aggregate includes a first serpentine aggregate and a second serpentine aggregate, wherein the particle size of the first serpentine aggregate is 5mm to 20mm, and the particle size of the second serpentine aggregate is 0.3mm to 5mm.

[0023] In some embodiments of this application, the serpentine aggregate satisfies at least one of the following conditions:

[0024] (1) The first serpentine aggregate includes a first-size aggregate and a second-size aggregate, wherein the first-size aggregate has a particle size of 10 mm to 20 mm and the second-size aggregate has a particle size of 5 mm to 10 mm.

[0025] Optionally, the mass ratio of the first aggregate size to the second aggregate size is 5:5 to 7:3;

[0026] (2) The fineness modulus of the second serpentine aggregate is 2.3~3.0, and the sand ratio is 0.40~0.45;

[0027] (3) The weight of the first serpentine aggregate in the serpentine aggregate is 900 to 1100 parts;

[0028] (4) The weight of the second serpentine aggregate in the serpentine aggregate is 600 to 700 parts.

[0029] In some embodiments of this application, the water-reducing agent includes one or more of phosphate water-reducing agents, fatty acid water-reducing agents, and polycarboxylate water-reducing agents.

[0030] In some embodiments of this application, at least one of the following conditions is met:

[0031] (1) The concrete contains CaB6O 10 ·5H2O;

[0032] (2) The water-cement ratio of the concrete is 0.40~0.50.

[0033] The second aspect of this application provides a method for preparing the neutron radiation-protected concrete described in the first aspect of this application, comprising:

[0034] The serpentine aggregate is pre-cleaned to remove asbestos fibers from it.

[0035] The pre-cleaned serpentine aggregate is mixed with the gel material, the water-reducing agent, the aqueous solution containing borate, and the mixing water, and then left to stand to prepare the neutron radiation-protected concrete.

[0036] The raw materials for the neutron radiation protection concrete provided in this application include the above-mentioned components. After mixing the components, the borate ions can come into contact with the cement included in the gel material and react with components such as Ca(OH)2 contained in the cement itself to generate in situ calcium borate (CaB6O3) which can act as a neutron absorber. 10 The neutron absorber can be uniformly distributed in concrete through this in-situ reaction (·5H2O), thereby structurally improving the neutron shielding performance of concrete. Attached Figure Description

[0037] Figure 1 This is an X-ray diffraction analysis diagram of gorborite according to one embodiment of this application.

[0038] Figure 2 This is a topographic image of the interface transition zone of concrete after 28 days of standing, according to one embodiment of this application.

[0039] Figure 3The image shows a cross-sectional view of concrete after being left to stand for 28 days according to one embodiment of this application; in (a), the gelling material used to prepare the concrete is only cement, and in (b), the gelling material used to prepare the concrete includes cement, mineral powder and fly ash. Detailed Implementation

[0040] To facilitate understanding of this application, a more complete description will be provided below. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0041] For simplicity, this application only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form a range not explicitly stated; and any lower limit can be combined with other lower limits to form a range not explicitly stated, just as any upper limit can be combined with any other upper limit to form a range not explicitly stated. Furthermore, although not explicitly stated, every point or individual value between the endpoints of the range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit and combined with any other point or individual value or with other lower or upper limits to form a range not explicitly stated.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. It should be noted that, unless otherwise stated, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items, "above," "below," includes the stated number, and "one or more" with "multiple" means two or more.

[0043] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0044] Currently, radiation-shielding concrete often uses aggregates rich in water of crystallization. During their research, the inventors discovered that, compared with traditional radiation-shielding polymer shielding materials, radiation-shielding concrete using aggregates rich in water of crystallization has a higher service temperature. In high-temperature environments (such as above 300°C), it can utilize the water of crystallization contained in its aggregates, which contains a large amount of hydrogen. The hydrogen nuclei have a good protective effect against high-speed neutrons and can slow down high-speed neutrons, thereby improving the shielding effect. However, the effect of using only the water of crystallization in the aggregates to improve the shielding effect of radiation-shielding concrete is very limited.

[0045] Furthermore, commonly used aggregates rich in crystal water mainly include limonite and serpentine aggregates. Limonite has a crystal water content ranging from 8% to 12%, while serpentine has a crystal water content ranging from 12% to 13%. However, limonite loses 8.9% of its crystal water at 400℃, while serpentine shows no mass loss below 400℃ and exhibits good thermal stability, making it a valuable material for neutron shielding concrete. However, serpentine has a layered structure and low hardness, resulting in a high content of needle-like and flaky serpentine fragments and sand from crushed serpentine ore. The inventors discovered that a high content of needle-like and flaky aggregates in concrete severely affects its workability and mechanical properties. Moreover, serpentine aggregates often contain asbestos fibers, leading to low mechanical strength and resulting in low slump, poor fluidity, and insufficient compressive strength to meet the structural material requirements of the shielding concrete.

[0046] To solve the aforementioned technical problems, the inventors have proposed the following technical solution in this application.

[0047] The first aspect of this application provides a neutron radiation-protected concrete, comprising the following raw materials: serpentine aggregate, gel material, water-reducing agent, aqueous solution containing borate, and mixing water, wherein the gel material includes cement.

[0048] The raw materials for the neutron radiation protection concrete provided in this application include the above-mentioned components. After mixing the components, the borate ions can come into contact with the cement included in the gel material and react with components such as Ca(OH)2 contained in the cement itself to generate in situ calcium borate (CaB6O3) which can act as a neutron absorber. 10 The neutron absorber can be uniformly distributed in concrete through this in-situ reaction (·5H2O), thereby structurally improving the neutron shielding effect of concrete.

[0049] Among them, the goniocalcium ore neutron absorber can solidify more H2O, increase the content of crystal water and hydrogen in concrete, and slow down more high-speed neutrons by hydrogen nuclei, thereby improving the slowing effect of hydrogen nuclei on high-speed neutrons and enhancing the shielding performance of concrete against neutrons. On the other hand, the boron element introduced into the goniocalcium ore neutron absorber can also capture neutrons and undergo the reaction shown in equation (1), thereby effectively improving the absorption performance of concrete against neutrons and further enhancing the shielding performance of concrete against neutrons. In addition, more neutrons slowed down by hydrogen nuclei can be more easily captured and absorbed by boron, thereby increasing the capture and absorption rate of boron against neutrons. Thus, through the synergistic effect between hydrogen and boron in goniocalcium ore, the shielding effect of concrete against neutrons can be effectively improved, and excellent neutron radiation protection performance can be obtained.

[0050] (1).

[0051] In some embodiments, the weight parts of each component in the raw material are as follows: serpentine aggregate, 1500-1800 parts; gel material, 400-520 parts; water-reducing agent, 30-40 parts; aqueous solution containing borate, 25-35 parts; and mixing water, 140-180 parts.

[0052] In some embodiments, the serpentine aggregate may be 1500 parts, 1600 parts, 1700 parts, 1800 parts, or within any of the above values.

[0053] In some embodiments, the gel material may be 400 parts, 450 parts, 500 parts, 520 parts, or within any of the above values.

[0054] In some embodiments, the water-reducing agent may be 30 parts, 35 parts, 40 parts, or within any of the above values.

[0055] In some embodiments, the aqueous solution containing borate may be 25 parts, 30 parts, 35 parts, or within any of the above values.

[0056] In some embodiments, the mixing water may be 140 parts, 160 parts, 180 parts, or within any of the above values.

[0057] In some embodiments, the concentration of borate in the aqueous solution containing borate is 0.01 g / mL to 0.05 g / mL.

[0058] It should be noted that the aqueous solution containing boric acid in this application can be prepared by dissolving boric acid and / or soluble borates in water. The soluble borates include, but are not limited to, at least one of sodium borate, potassium borate, and calcium borate.

[0059] In some embodiments, the serpentine aggregate does not contain asbestos fibers.

[0060] The inventors discovered through research that serpentine aggregates typically contain clay-like substances and asbestos fibers, which are associated minerals of serpentine. Clay-like substances and asbestos fibers have strong water absorption. When the content of these two substances is high, it can lead to a significant increase in the water demand of concrete. Furthermore, due to the tensile effect of asbestos fibers, it can have an adverse effect on the mechanical properties and workability of concrete.

[0061] Therefore, the serpentine aggregate of this application does not contain asbestos fibers, which can effectively reduce the water absorption of concrete and effectively improve the mechanical strength, slump and fluidity of concrete.

[0062] In some embodiments, the cement in the gel material comprises 280 to 360 parts by weight. For example, the cement may be 280, 300, 320, 340, 360 parts by weight, or any of the above values.

[0063] In some embodiments, the cement includes silicate cement.

[0064] Optionally, the strength grade of the silicate cement is ≥52.5.

[0065] It is understandable that the above "strength grade of silicate cement ≥ 52.5" refers to silicate cement of grade PO 52.5 or higher as specified in GB / T 175.

[0066] This application uses silicate cement with a strength grade of ≥52.5, which can further improve the compressive strength of the concrete after solidification, and at the same time improve the neutron shielding performance of the concrete, it can give the concrete good structural strength.

[0067] In some embodiments, the gel material further includes mineral powder and fly ash.

[0068] It should be noted that the mineral powder used in this application is S105 grade product as required by GB / T 18046; the fly ash used is Grade I product as required by GB / T1596.

[0069] The gelling material provided in this application includes cement, mineral powder, and fly ash. The fly ash can be uniformly distributed in the matrix of the cement paste through activity effects, morphology effects, and micro-aggregate effects, thereby improving its mechanical properties and high-temperature service performance. See also... Figure 2In the morphology diagram of the interface transition zone after 28 days of concrete standing, the closer to the interface transition zone, the more unhydrated fly ash is distributed, indicating that the fly ash reaction in the interface transition zone is relatively slow, and the strength increase is slower compared to other areas. Because serpentine aggregate has water absorption properties, it competes with the cementitious materials for moisture, resulting in less complete hydration of the cementitious materials (CSH gel, CaO·xSiO2·yH2O) in the interface transition zone compared to other areas. Since fly ash has a micro-aggregate filling effect, its incorporation can fill the pores in the interface transition zone, enhancing its strength and thus increasing the mechanical strength of the concrete.

[0070] In some embodiments, the weight percentage of the mineral powder in the gel material is 60 to 80 parts. For example, the weight percentage of the mineral powder can be 60, 70, or 80 parts, or any of the above values.

[0071] In some embodiments, the fly ash in the gel material comprises 60 to 80 parts by weight. For example, the fly ash may be 60, 70, or 80 parts by weight, or fall within any of the above ranges.

[0072] Due to the presence of unburned carbon particles and loose glassy particles in fly ash, a relatively high fly ash content in concrete will increase the water demand of the cement, affecting its use. Meanwhile, mineral powder mainly contains dense glassy particles; a relatively high mineral powder content with relatively low powder fineness will reduce the water demand of the cement and easily lead to bleeding. Therefore, this application adopts a composite admixture method of mineral powder and fly ash, which can achieve a super-synergistic effect when used together. In this way, while reducing the cement water-cement ratio, the compressive strength and heat resistance of the concrete can be improved.

[0073] In some embodiments, the average particle size of the mineral powder is 50 μm to 100 μm.

[0074] In some embodiments, the average particle size of fly ash is 50 μm to 100 μm.

[0075] Meanwhile, by controlling the amount and particle size of mineral powder and fly ash within a suitable range, the super synergistic effect of their combined use can be effectively enhanced, thereby further improving the compressive strength and heat resistance of concrete.

[0076] In some embodiments, the mineral powder contains CaO, SiO2, Al2O3, and MgO.

[0077] In some embodiments, the mineral powder contains 30% to 42% CaO by mass, 35% to 38% SiO2 by mass, 10% to 18% Al2O3 by mass, and 5% to 14% MgO by mass.

[0078] In some embodiments, the fly ash contains SiO2, Al2O3, Fe2O3 and CaO.

[0079] In some embodiments, the fly ash contains SiO2 at a mass percentage of 34% to 51%, Al2O3 at a mass percentage of 17% to 30%, CaO at a mass percentage of 1% to 10%, and Fe2O3 at a mass percentage of 5% to 15%.

[0080] In some embodiments, the serpentine aggregate includes a first serpentine aggregate and a second serpentine aggregate, wherein the particle size of the first serpentine aggregate is 5mm to 20mm and the particle size of the second serpentine aggregate is 0.3mm to 5mm.

[0081] In some embodiments, the first serpentine aggregate comprises a first-size aggregate and a second-size aggregate, wherein the first-size aggregate has a particle size of 10 mm to 20 mm, and the second-size aggregate has a particle size of 5 mm to 10 mm. For example, the particle size of the first-size aggregate can be 10 mm, 15 mm, 20 mm, or any range thereof. The particle size of the second-size aggregate can be 5 mm, 8 mm, 10 mm, or any range thereof.

[0082] In some embodiments, the mass ratio of the first aggregate to the second aggregate is 5:5 to 7:3. For example, the mass ratio of the first aggregate to the second aggregate can be 5:5, 5:4, 5:3, 6:5, 6:4, 6:3, 7:5, 7:4, 7:3, or within any of the above values.

[0083] In serpentine aggregate, the first serpentine aggregate meets the above gradation, that is, the particle size and mass ratio of the first and second aggregates are within the above range, which is beneficial to further improve the mechanical properties of concrete.

[0084] In some embodiments, the fineness modulus of the second serpentine aggregate is 2.3 to 3.0, and the sand ratio is 0.40 to 0.45. A sand ratio within this range for the second serpentine aggregate is beneficial for improving the workability of concrete.

[0085] In some embodiments, the weight percentage of the first serpentine aggregate in the serpentine aggregate is 900 to 1100 parts. For example, the weight percentage of the first serpentine aggregate can be 900 parts, 1000 parts, 1100 parts, or within any of the above values.

[0086] In some embodiments, the weight percentage of the second serpentine aggregate in the serpentine aggregate is 600 to 700 parts. For example, the weight percentage of the second serpentine aggregate can be 600 parts, 650 parts, 700 parts, or any of the above values.

[0087] In some embodiments, the water-reducing agent includes, but is not limited to, one or more of phosphate water-reducing agents, fatty acid water-reducing agents, and polycarboxylate water-reducing agents. The water-reducing agent can further improve the strength of concrete and reduce shrinkage of concrete under high-temperature service conditions.

[0088] In some embodiments, tap water is used for mixing, in accordance with the relevant provisions of JGJ 63.

[0089] In some embodiments, the concrete contains CaB6O. 10 ·5H2O.

[0090] In some embodiments, the water-cement ratio of the concrete is 0.40 to 0.50.

[0091] The second aspect of this application provides a method for preparing neutron radiation-protected concrete as described in the first aspect of this application, which may include the following steps:

[0092] S1. Pre-clean the serpentine aggregate to remove asbestos fibers from the serpentine aggregate;

[0093] S2. The pre-cleaned serpentine aggregate is mixed with the gel material, the water-reducing agent, the aqueous solution containing borate, and the mixing water, and then left to stand to prepare the neutron radiation protection concrete.

[0094] It should be noted that in step S1, the serpentine aggregate can undergo multiple cleaning processes to ensure that its methylene blue value is less than 1.4, thereby removing the associated asbestos fibers.

[0095] Thus, this application uses higher grade cement to improve concrete strength, pre-cleaning serpentine aggregate to improve concrete workability, and the combined use of mineral powder and fly ash, along with the use of water-reducing agents, can reduce water consumption and improve concrete slump index. At the same time, by introducing in-situ generated gorgonite neutron absorber, further absorption of thermal neutrons slowed by hydrogen can be achieved, thus producing a concrete material suitable for pump-casting neutron radiation protection.

[0096] Example

[0097] The following are specific embodiments, which describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations within the scope of the disclosure of this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0098] The sources of the raw materials used in the following embodiments and comparative examples are as follows:

[0099] High-performance carboxylic acids: Tianjin Zhongtai Materials Technology Co., Ltd.

[0100] Serpentine aggregate: Hubei Wande Chemical Co., Ltd.

[0101] Cement: Guangdong Qingxin Cement Co., Ltd.

[0102] Mineral powder: Hebei Chuangtian Engineering Materials Co., Ltd.

[0103] Fly ash: Hebei Kexu Building Materials Co., Ltd.

[0104] Example 1

[0105] S1. Pre-clean the coarse and fine serpentine aggregates to ensure that the methylene blue value test result is less than 1.4;

[0106] S2. Add serpentine coarse aggregate, serpentine fine aggregate and high-performance carboxylic acid to the mixer and mix for 30 seconds. Then add cement, mineral powder and fly ash and mix for 15 seconds. After that, add 1 / 3 of the mixing water and boric acid solution and mix for 30 seconds. Then add the remaining mixing water and boric acid solution and mix for 60 seconds.

[0107] S3. After discharge, pour the concrete into the cavity and carry out subsequent curing to obtain concrete samples.

[0108] The serpentine coarse aggregate has a particle size of 5mm~20mm and a mix proportion of 1000kg / m³. 3 The serpentine fine aggregate has a particle size of 0.3mm~5mm and a mix ratio of 700kg / m³. 3 The cement used is silicate cement with a grade of PO52.5, and the mix proportion is 300 kg / m³. 3 The mineral powder used is S105, with a mixing ratio of 70 kg / m³. 3 The fly ash used is Grade I, with a mix ratio of 70 kg / m³. 3 The mixing water is tap water, and the mixing ratio is 180 kg / m³. 3 The water-reducing agent is a high-performance carboxylic acid, with a mixing ratio of 20 kg / m³.3 The concentration of the boric acid solution is 0.02 g / mL, and the mixing ratio is 30 kg / m³. 3 .

[0109] Example 2

[0110] Similar to the preparation method in Example 1, the main difference is that in step S2, mineral powder with an equal proportion is used instead of fly ash (i.e., no fly ash is added).

[0111] Example 3

[0112] Similar to the preparation method in Example 1, the main difference is that in step S2, fly ash with an equal proportion is used instead of mineral powder (i.e., no mineral powder is added).

[0113] Example 4

[0114] The preparation method is similar to that in Example 1, the main difference being that the proportion of mineral powder in step S2 is 60 kg / m³. 3 .

[0115] Example 5

[0116] The preparation method is similar to that in Example 1, the main difference being that the proportion of mineral powder in step S2 is 80 kg / m³. 3 .

[0117] Example 6

[0118] The preparation method is similar to that in Example 1, the main difference being that the proportion of mineral powder in step S2 is 50 kg / m³. 3 .

[0119] Example 7

[0120] The preparation method is similar to that in Example 1, the main difference being that the proportion of mineral powder in step S2 is 90 kg / m³. 3 .

[0121] Example 8

[0122] The preparation method is similar to that in Example 1, the main difference being that the proportion of fly ash in step S2 is 60 kg / m³. 3 .

[0123] Example 9

[0124] The preparation method is similar to that in Example 1, the main difference being that the proportion of fly ash in step S2 is 80 kg / m³. 3 .

[0125] Example 10

[0126] The preparation method is similar to that in Example 1, the main difference being that the proportion of fly ash in step S2 is 50 kg / m³. 3 .

[0127] Example 11

[0128] The preparation method is similar to that in Example 1, the main difference being that the proportion of fly ash in step S2 is 90 kg / m³. 3 .

[0129] Comparative Example 1

[0130] The preparation method is similar to that in Example 1, the main difference being that boric acid solution is not added in step S2.

[0131] Comparative Example 2

[0132] Similar to the preparation method in Example 1, the main difference is that in step S2, a phosphoric acid solution of medium concentration and equal proportion is used instead of a boric acid solution.

[0133] Comparative Example 3

[0134] Similar to the preparation method in Example 1, the main difference is that in step S2, B4C with an equal proportion is used instead of boric acid solution.

[0135] Comparative Example 4

[0136] The preparation method is similar to that in Example 1, except that step S1 is omitted.

[0137] The concrete prepared in Examples 1-11 and Comparative Examples 1-4 were subjected to relevant performance tests, and the test results are shown in Table 1 below.

[0138] The test conditions or standards for each performance test item are as follows:

[0139] (1) The slump shall be measured in accordance with the provisions of Chapter 4 of GB / T 50080;

[0140] (2) The compressive strength shall be tested in accordance with the provisions of GB / T 50081;

[0141] (3) Flexural strength shall be tested in accordance with the provisions of GB / T 50081;

[0142] (4) The hydrogen content is calculated based on the theoretical mix proportion;

[0143] (5) Neutron shielding performance: The neutron shielding coefficient of 50mm thick shielding concrete was tested under an Am-Be source;

[0144] (6) Morphology test: The morphology of concrete was tested using a scanning electron microscope (SEM).

[0145] Table 1

[0146]

[0147] Table 1 above shows that comparing Examples 1-11 with Comparative Examples 1-3, it can be seen that adding borate to the concrete raw materials provided in this application can effectively improve the neutron shielding effect of the concrete. Comparing Examples 1-11 with Comparative Example 4 shows that pre-cleaning the serpentine aggregate can effectively improve the mechanical properties of the concrete.

[0148] Furthermore, analysis of the data in Table 1 shows that after 7 days of curing, the concrete continues to hydrate. The hydration products can fill the micropores of the serpentine concrete, optimizing the pore structure and strengthening the interface transition zone between aggregates and paste. Ultimately, this results in a significant increase in the 28-day compressive strength of the mineral admixture mix compared to the 7-day strength. Simultaneously, through the pozzolanic effect, it consumes a large amount of free-state Ca(OH)₂, reducing the alkalinity of the liquid phase and improving the durability of the concrete.

[0149] In addition, from Figure 3 It can be seen that, compared with the mixture in (a) which does not use mineral powder and fly ash, the concrete in (b) which uses mineral powder and fly ash has fewer pores after standing for 28 days, and therefore has better mechanical properties.

[0150] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0151] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A concrete for neutron radiation protection, characterized in that, The raw materials include: serpentine aggregate, gel material, water-reducing agent, aqueous solution containing borate, and mixing water. The gel material includes cement, mineral powder, and fly ash. The weight parts of the mineral powder in the gel material are 60 to 80 parts, and the weight parts of the fly ash in the gel material are 60 to 80 parts. The weight parts of each component in the raw material are as follows: serpentine aggregate, 1500-1800 parts; gel material, 400-520 parts; water-reducing agent, 30-40 parts; aqueous solution containing borate, 25-35 parts; and mixing water, 140-180 parts. The serpentine aggregate does not contain asbestos fibers; The concentration of borate ions in the aqueous solution containing borate ions is 0.01 g / mL to 0.05 g / mL; The cement in the gel material is in the form of 280 to 360 parts by weight. The cement includes silicate cement, and the strength grade of the silicate cement is ≥52.

5.

2. The neutron radiation shielding concrete according to claim 1, characterized in that, One or more of the following conditions must be met: (1) The average particle size of the mineral powder is 50 μm to 100 μm; (2) The average particle size of the fly ash is 50μm~100μm.

3. The neutron radiation protection concrete according to claim 1 or 2, characterized in that, At least one of the following conditions must be met: (1) The mineral powder contains CaO, SiO2, Al2O3 and MgO; (2) The fly ash contains SiO2, Al2O3, Fe2O3 and CaO.

4. The neutron radiation protection concrete according to claim 3, characterized in that, One or more of the following conditions must be met: (1) In the mineral powder, the mass percentage of CaO is 30%~42%, the mass percentage of SiO2 is 35%~38%, the mass percentage of Al2O3 is 10%~18%, and the mass percentage of MgO is 5%~14%; (2) In the fly ash, the mass percentage of SiO2 is 34%~51%, the mass percentage of Al2O3 is 17%~30%, the mass percentage of CaO is 1%~10%, and the mass percentage of Fe2O3 is 5%~15%.

5. The neutron radiation protection concrete according to claim 1 or 2, characterized in that, The serpentine aggregate includes a first serpentine aggregate and a second serpentine aggregate. The particle size of the first serpentine aggregate is 5mm to 20mm, and the particle size of the second serpentine aggregate is 0.3mm to 5mm.

6. The neutron radiation protection concrete according to claim 5, characterized in that, The serpentine aggregate meets at least one of the following conditions: (1) The first serpentine aggregate includes a first-size aggregate and a second-size aggregate, wherein the first-size aggregate has a particle size of 10 mm to 20 mm and the second-size aggregate has a particle size of 5 mm to 10 mm. (2) The fineness modulus of the second serpentine aggregate is 2.3~3.0, and the sand ratio is 0.40~0.45; (3) The weight of the first serpentine aggregate in the serpentine aggregate is 900 to 1100 parts; (4) The weight of the second serpentine aggregate in the serpentine aggregate is 600 to 700 parts.

7. The neutron radiation shielding concrete according to claim 6, characterized in that, The mass ratio of the first aggregate size to the second aggregate size is 5:5 to 7:

3.

8. The neutron radiation protection concrete according to claim 1 or 2, characterized in that, The water-reducing agent includes one or more of phosphate water-reducing agents, fatty acid water-reducing agents, and polycarboxylate water-reducing agents.

9. The neutron radiation protection concrete according to claim 1 or 2, characterized in that, At least one of the following conditions must be met: (1) the concrete contains CaB6O 10 * 5H2O; (2) The water-cement ratio of the concrete is 0.40~0.

50.

10. A method for preparing neutron radiation-protected concrete according to any one of claims 1-9, characterized in that, include: The serpentine aggregate is pre-cleaned to remove asbestos fibers from it. The pre-cleaned serpentine aggregate is mixed with the gel material, the water-reducing agent, the aqueous solution containing borate, and the mixing water, and then left to stand to prepare the neutron radiation-protected concrete.

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