A concrete for slowing down and absorbing neutrons and a method for producing the same

Abstract

This invention belongs to the field of concrete building materials technology, and discloses a type of concrete that moderates and absorbs neutrons and its preparation method. The concrete comprises the following raw materials per cubic meter: 400-550 kg / m³ of boron-containing cement. 3 Functional admixtures 140~300kg / m³ 3 Heavy coarse and fine aggregates: 2450–2850 kg / m³ 3 Metal hydrides 6-15 kg / m 3 Water-reducing agent 8-12 kg / m³ 3 Rheology modifier 3-5 kg / m 3 Stabilizer 2-6 kg / m 3 The water-cement ratio is 0.35–0.45. This invention is the first to introduce metal hydrides into concrete. Combined with other raw materials, it can achieve dual radiation protection functions of slowing down and absorbing neutrons while ensuring the mechanical and durability properties of concrete. It is an environmentally friendly functional concrete material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete building materials, and particularly relates to a concrete capable of slowing down and absorbing neutrons and a preparation method thereof. BACKGROUND

[0002] To alleviate the energy crisis, more sufficient and efficient energy must be developed. Nuclear energy, as a clean, stable and efficient energy, is used by many countries in the world. With the development of the world industry, the proportion of nuclear energy in the global energy structure is increasing year by year, and the number of nuclear power plants in operation and under construction is increasing year by year. In addition, nuclear technology is also widely used in medical treatment, scientific research, military and other fields. Thus, the harm of nuclear radiation is increasing. The neutron flow generated in the process of application of nuclear technology causes radiation pollution of air, water and soil environment, and causes gene mutation of organisms in the radiation range. Animals and plants exposed to the radiation-polluted environment for a long time will induce chromosomal diseases, various deformities and even death. When the human body is exposed to radiation, symptoms such as vomiting, diarrhea, skin burns, hair loss, eye pain and leukopenia will occur. And it will induce diseases such as thyroid cancer, leukemia and birth defects, which seriously endanger human health. Therefore, the first criterion for the use of nuclear technology is safety and radiation protection.

[0003] With the rapid development of nuclear power, scientific research, medical treatment and military and other fields, the demand for protection materials for slowing down neutrons and reducing neutron energy, especially for anti-radiation building materials, will greatly increase. Therefore, it is of great practical significance and application value to develop an environment-friendly anti-radiation concrete with the functions of slowing down and absorbing neutrons. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a concrete capable of slowing down and absorbing neutrons and a preparation method thereof, which can slow down and absorb neutrons while ensuring the mechanical properties and durability of the concrete, so as to have double radiation protection performance.

[0005] To solve the technical problem proposed in the present application, the present application provides a concrete capable of slowing down and absorbing neutrons, which comprises the following raw materials by weight per cubic meter: 400-550 kg / m of boron-containing cement 3 , 140-300 kg / m of functional admixture 3 , 2450-2850 kg / m of heavy coarse and fine aggregate 3 , 6-15 kg / m of metal hydride 3 , 8-12 kg / m of water reducing agent 3 , 3-5 kg / m of rheological agent 3 , 2-6 kg / m of stabilizer 3 , and water-cement ratio of 0.35-0.45.

[0006] In the scheme, the mass content of calcium borate in the boron-containing cement is greater than or equal to 10%.

[0007] In the scheme, the functional admixture is chromium ore powder and boron carbide with a mass ratio of (1-3):1, and the specific surface area is greater than or equal to 550 m 2 / kg.

[0008] Further, the mass content of Cr2O3 in the chromium ore powder is greater than or equal to 40%.

[0009] Further, the effective content of the boron carbide is greater than or equal to 90%.

[0010] In the scheme, the heavy coarse aggregate is a continuous gradation of galena particles with a mass content of lead greater than or equal to 60%, and the particle size is 0.45-10 mm.

[0011] In the scheme, the metal hydride is zirconium hydride and yttrium hydride with a mass ratio of (1-5):1, and the specific surface area is greater than or equal to 300 m 2 / kg.

[0012] In the scheme, the water reducing agent is a melamine-based high-efficiency water reducing agent.

[0013] In the scheme, the rheological agent is a polyethyleneimine aqueous solution with a mass concentration of 20-50%, a molecular weight of 600-150000, and a viscosity of 3300-20500 mPa·s.

[0014] In the scheme, the stabilizer is one or both of xanthan gum and xanthan gum.

[0015] The application also provides a preparation method of the concrete for slowing down and absorbing neutrons, comprising the following steps:

[0016] 1) sequentially adding the heavy coarse aggregate and the boron-containing cement into a mixer, and stirring to obtain a first mixture;

[0017] 2) sequentially adding the functional admixture, the metal hydride, and the stabilizer into the first mixture, and stirring to obtain a second mixture;

[0018] 3) adding the rheological agent, the water reducing agent, and water into the second mixture, and stirring to obtain the concrete for slowing down and absorbing neutrons.

[0019] In the scheme, the stirring rate in step 1) is 30-60 r / min, and the stirring time is 1-2 min; the stirring rate in step 2) is 30-60 r / min, and the stirring time is 3-4 min; and the stirring rate in step 3) is 120-180 r / min, and the stirring time is 3-4 min.

[0020] In the scheme, the maintenance condition of the concrete for slowing down and absorbing neutrons is: normal temperature environment maintenance after molding and before demolding, and normal temperature maintenance with surface wetting by spraying water within 7 days after demolding.

[0021] The technical idea of the present application is:

[0022] The present application adopts the design idea of slowing down and absorbing neutrons, and the combination of the two plays a double radiation protection effect. For the first time, metal hydride is introduced into the concrete, which not only provides hydrogen elements that can slow down neutrons, but also provides heavy metal elements that can absorb neutrons. Each component can fully play the function of radiation protection, and has double efficiency. In terms of slowing down neutrons, the high content of hydrogen in metal hydride has good ability to slow down neutrons, and the crystal water of cementitious material hydration product can efficiently slow down neutron flow and reduce the energy of neutrons. In terms of absorbing neutrons, in addition to zirconium and yttrium in metal hydride, cementitious material containing boron elements can also absorb neutrons; the continuous grading of heavy coarse and fine aggregates containing lead elements can not only adjust the grading to avoid aggregate settlement and paste segregation, but also further absorb neutrons; the mineral admixtures containing boron and chromium are mixed, and boron and chromium elements can absorb a large amount of slow neutrons. At the same time, high content of mineral admixtures can provide a large amount of amorphous components, which can have secondary hydration reaction with cement hydration products, and improve the strength and durability of concrete.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] For the first time, metal hydride is introduced into the concrete, and in combination with the crystal water in the cementitious material hydration product, the neutron flow can be efficiently slowed down, and the energy of neutrons can be reduced. The shielding elements such as lead, chromium, zirconium, yttrium and boron in the concrete have the ability to absorb neutrons, and thus the neutrons after slowing down are absorbed. Therefore, the present application not only can effectively slow down the neutron flow generated in the process of nuclear technology application, but also can absorb part of the slowed down neutrons, and has a double radiation protection effect. It is an environment-friendly functional concrete material. DETAILED DESCRIPTION

[0025] In order to better understand the present application, the content of the present application will be further illustrated by the following examples, but the content of the present application is not limited to the following examples.

[0026] In the following examples, the boron-containing cement used is a boron-containing cement with tricalcium silicate, dicalcium silicate and calcium borate as main clinker minerals, and the mass content of calcium borate is 12.5%; the chromium ore powder is a commercially available chromium ore powder, and the mass content of Cr2O3 is 42.6%, and the specific surface area is 596 m 2 / kg; the effective content of boron carbide is 92.3%, and the specific surface area is 584 m 2 / kg; the heavy coarse aggregate is a 0.45-10mm continuously graded galena particle, wherein the mass content of lead is 63.4%; the specific surface areas of the zirconium hydride and the yttrium hydride are 336m 2 / kg and 316m 2 / kg respectively; the water reducing agent is a F10 type melamine based high efficiency water reducing agent produced by BASF China Co., Ltd., the effective content is 92%, and the water reducing rate is 28%; the rheological agent is a polyethylene imine aqueous solution with a mass concentration of 40%, a molecular weight of 90000, and a viscosity of 15000mPa·s.

[0027] Example 1

[0028] The concrete for slowing down and absorbing neutrons in this example comprises the following raw materials by weight per cubic meter: boron-containing cement 400kg / m 3 , functional admixture 300kg / m 3 , heavy coarse aggregate 2850kg / m 3 , metal hydride 6kg / m 3 , water reducing agent 8kg / m 3 , rheological agent 3kg / m 3 , stabilizer 2kg / m 3 , and water-cement ratio 0.45.

[0029] The functional admixture is chromium ore powder and boron carbide with a mass ratio of 1:1, the metal hydride is zirconium hydride and yttrium hydride with a mass ratio of 1:1, and the stabilizer is xanthan gum.

[0030] The preparation method of the concrete for slowing down and absorbing neutrons in this example comprises the following steps:

[0031] 1) The heavy coarse aggregate and the boron-containing cement are sequentially added into a mixer, and stirred at a speed of 30r / min for 2min to obtain a first mixture;

[0032] 2) The functional admixture, the metal hydride and the stabilizer are sequentially added into the first mixture, and stirred at a speed of 30r / min for 4min to obtain a second mixture;

[0033] 3) The rheological agent, the water reducing agent and water are added into the second mixture, and stirred at a speed of 120r / min for 4min to obtain the concrete for slowing down and absorbing neutrons.

[0034] The concrete for slowing down and absorbing neutrons is loaded into a mold, and naturally cured in a normal temperature environment. After molding, it is demolded, and then naturally cured in a normal temperature environment with the surface kept wet by watering within 7 days after demolding. After 7 days, it is naturally cured in a normal temperature environment.

[0035] Example 2

[0036] The concrete for slowing down and absorbing neutrons of the embodiment comprises the following raw materials by weight per cubic meter: boron-containing cement 440 kg / m 3 functional admixture 260 kg / m 3 heavy coarse and fine aggregate 2690 kg / m 3 metal hydride 8 kg / m 3 water reducing agent 9 kg / m 3 rheological agent 3.5 kg / m 3 stabilizer 3 kg / m 3 and water-cement ratio 0.42.

[0037] The functional admixture is chromium ore powder and boron carbide at a mass ratio of 1.5:1, the metal hydride is zirconium hydride and yttrium hydride at a mass ratio of 2:1, and the stabilizer is xanthan gum.

[0038] The preparation method of the concrete for slowing down and absorbing neutrons of the embodiment comprises the following steps:

[0039] 1) The heavy coarse and fine aggregate and the boron-containing cement are sequentially added into a mixer, and stirred at a speed of 45 r / min for 2 min to obtain a first mixture;

[0040] 2) The functional admixture, the metal hydride and the stabilizer are sequentially added into the first mixture, and stirred at a speed of 45 r / min for 4 min to obtain a second mixture;

[0041] 3) The rheological agent, the water reducing agent and water are added into the second mixture, and stirred at a speed of 150 r / min for 4 min to obtain the concrete for slowing down and absorbing neutrons.

[0042] The concrete for slowing down and absorbing neutrons is loaded into a mold, and naturally cured in a normal temperature environment. After molding, the concrete is demolded, and then naturally cured in a normal temperature environment with water spraying for keeping the surface wet within 7 days after demolding, and then naturally cured in a normal temperature environment after 7 days.

[0043] Embodiment 3

[0044] The concrete for slowing down and absorbing neutrons of the embodiment comprises the following raw materials by weight per cubic meter: boron-containing cement 460 kg / m 3 functional admixture 240 kg / m 3 heavy coarse and fine aggregate 2580 kg / m 3 metal hydride 11 kg / m 3 water reducing agent 10 kg / m 3 rheological agent 4 kg / m 3 stabilizer 4 kg / m 3 and water-cement ratio 0.41.

[0045] The functional admixture is chromium ore powder and boron carbide with a mass ratio of 2:1, the metal hydride is zirconium hydride and yttrium hydride with a mass ratio of 3:1, and the stabilizer is xanthan gum and xanthan gum with a mass ratio of 4:1.

[0046] The preparation method of the concrete for slowing down and absorbing neutrons in the embodiment comprises the following steps:

[0047] 1) The heavy coarse aggregate and the boron-containing cement are sequentially added into a mixer, and stirred at a speed of 45 r / min for 1 min to obtain a first mixture;

[0048] 2) The functional admixture, the metal hydride and the stabilizer are sequentially added into the first mixture, and stirred at a speed of 60 r / min for 3 min to obtain a second mixture;

[0049] 3) The rheological agent, the water reducing agent and water are added into the second mixture, and stirred at a speed of 180 r / min for 3 min to obtain the concrete for slowing down and absorbing neutrons.

[0050] The concrete for slowing down and absorbing neutrons is loaded into a mold, and naturally cured in a normal temperature environment. After molding, the concrete is demolded, and then naturally cured in a normal temperature environment with water spraying for keeping the surface wet within 7 days after demolding. After 7 days, the concrete is naturally cured in a normal temperature environment.

[0051] Example 4

[0052] The concrete for slowing down and absorbing neutrons in the embodiment comprises the following raw materials by weight per square meter: boron-containing cement 500 kg / m 3 , functional admixture 200 kg / m 3 , heavy coarse aggregate 2530 kg / m 3 , metal hydride 13 kg / m 3 , water reducing agent 11 kg / m 3 , rheological agent 4.5 kg / m 3 , stabilizer 5 kg / m 3 , and water-cement ratio 0.38.

[0053] The functional admixture is chromium ore powder and boron carbide with a mass ratio of 2.5:1, the metal hydride is zirconium hydride and yttrium hydride with a mass ratio of 4:1, and the stabilizer is xanthan gum and xanthan gum with a mass ratio of 2:3.

[0054] The preparation method of the concrete for slowing down and absorbing neutrons in the embodiment comprises the following steps:

[0055] 1) The heavy coarse aggregate and the boron-containing cement are sequentially added into a mixer, and stirred at a speed of 60 r / min for 1 min to obtain a first mixture;

[0056] 2) adding functional admixture, metal hydride and stabilizer into the first mixture in sequence, stirring at a speed of 45 r / min for 4 min to obtain a second mixture;

[0057] 3) adding rheological agent, water reducing agent and water into the second mixture, stirring at a speed of 150 r / min for 3 min to obtain the concrete for slowing down and absorbing neutrons.

[0058] The concrete for slowing down and absorbing neutrons is loaded into a mold, and is naturally cured in a normal temperature environment. After molding, the concrete is demolded, and is maintained in a normal temperature environment with water spraying to keep the surface wet within 7 days after demolding. After 7 days, the concrete is naturally cured in a normal temperature environment.

[0059] Example 5

[0060] The concrete for slowing down and absorbing neutrons of the example comprises the following raw materials by weight per cubic meter: boron-containing cement 550 kg / m 3 , functional admixture 150 kg / m 3 , heavy coarse and fine aggregate 2450 kg / m 3 , metal hydride 15 kg / m 3 , water reducing agent 12 kg / m 3 , rheological agent 5 kg / m 3 , stabilizer 6 kg / m 3 , and water-cement ratio 0.35.

[0061] The functional admixture is chromium ore powder and boron carbide at a mass ratio of 3:1, the metal hydride is zirconium hydride and yttrium hydride at a mass ratio of 5:1, and the stabilizer is xanthan gum and xanthan gum at a mass ratio of 1:5.

[0062] The preparation method of the concrete for slowing down and absorbing neutrons of the example comprises the following steps:

[0063] 1) adding heavy coarse and fine aggregate and boron-containing cement into a mixer in sequence, stirring at a speed of 60 r / min for 1 min to obtain a first mixture;

[0064] 2) adding functional admixture, metal hydride and stabilizer into the first mixture in sequence, stirring at a speed of 60 r / min for 3 min to obtain a second mixture;

[0065] 3) adding rheological agent, water reducing agent and water into the second mixture, stirring at a speed of 120 r / min for 4 min to obtain the concrete for slowing down and absorbing neutrons.

[0066] The concrete for slowing down and absorbing neutrons is loaded into a mold, and is naturally cured in a normal temperature environment. After molding, the concrete is demolded, and is maintained in a normal temperature environment with water spraying to keep the surface wet within 7 days after demolding. After 7 days, the concrete is naturally cured in a normal temperature environment.

[0067] Comparative Example 1

[0068] The difference between Comparative Example 1 and Example 1 is only that no metal cyanide is added.

[0069] Comparative Example 2

[0070] The difference between Comparative Example 2 and Example 2 is only that the functional admixture is a commercially available slag powder.

[0071] Comparative Example 3

[0072] The difference between Comparative Example 3 and Example 3 is only that the heavy coarse aggregate is a barite aggregate with a continuous gradation of 0.45-10 mm.

[0073] The concrete prepared in Examples 1-5 and Comparative Examples 1-3 is subjected to mechanical strength and durability performance tests, and the test methods refer to the standards GB / T 50081-2019 “Standard for Testing Methods for Mechanical Properties of Ordinary Concrete” and GB / T 50082-2009 “Standard for Testing Methods for Long-term Performance and Durability of Ordinary Concrete”; the performance test of the moderated neutron uses a Cf neutron source (irradiation energy 14.5 MeV) to irradiate the concrete test block, and the linear attenuation coefficient is determined. The performance test results are shown in the following table. 252 Cf neutron source (irradiation energy 14.5 MeV) to irradiate the concrete test block, and the linear attenuation coefficient is determined. The performance test results are shown in the following table.

[0074] Table 1 Performance test results

[0075]

[0076] From the test results, it can be seen that the examples of the present application can ensure the working performance and mechanical properties of the concrete while achieving the radiation protection performance of the moderated absorption of neutrons. Although Comparative Examples 1-3 have similar mechanical properties and durability performance to the corresponding examples, the moderated absorption of neutrons is significantly reduced.

[0077] The above examples are merely examples for clear illustration, and are not a limitation on the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art, and here it is not necessary or impossible to exhaust all the embodiments, and therefore the changes or variations thus extended are still within the protection scope of the present application.

Claims

1. A type of concrete that slows down and absorbs neutrons, characterized in that, Based on the weight per cubic meter, the following raw materials are included: 400~550 kg / m³ of boron-containing cement. 3 Functional admixtures 140~300 kg / m³ 3 Heavy coarse and fine aggregates: 2450~2850 kg / m³ 3 Metal hydrides 6~15 kg / m 3 Water-reducing agent 8~12 kg / m 3 Rheology modifier 3~5 kg / m 3 Stabilizer 2~6 kg / m 3 The water-cement ratio is 0.35~0.45; The functional admixture is chromite powder and boron carbide in a mass ratio of (1~3):1, with a specific surface area ≥550 m². 2 / kg; the heavy coarse and fine aggregates are galena particles with a continuous gradation of 0.45~10 mm, wherein the lead content by mass is ≥60%; the metal hydride is zirconium hydride and yttrium hydride in a mass ratio of (1~5):1, with a specific surface area ≥300 m². 2 / kg; the rheology modifier is a 20-50% (w / w) aqueous solution of polyethyleneimine with a molecular weight of 600-150000 and a viscosity of 3300-20500 mPa·s.

2. The concrete that slows down and absorbs neutrons according to claim 1, characterized in that, The chromite powder contains ≥40% Cr2O3 by mass and ≥90% effective boron carbide by effective mass.

3. The concrete that slows down and absorbs neutrons according to claim 1, characterized in that, The boron-containing cement contains ≥10% calcium borate by mass.

4. The concrete that slows down and absorbs neutrons according to claim 1, characterized in that, The water-reducing agent is a melamine-based high-efficiency water-reducing agent; the stabilizer is one or both of Werlen gum and xanthan gum.

5. The method for preparing concrete that moderates and absorbs neutrons according to any one of claims 1-4, characterized in that, Includes the following steps: 1) Add heavy coarse and fine aggregates and boron-containing cement to the mixer in sequence, and mix to obtain the first mixture; 2) Add the functional admixture, metal hydride, and stabilizer to the first mixture in sequence, and stir to obtain the second mixture; 3) Add rheology modifier, water-reducing agent and water to the second mixture, stir, and obtain slowed neutron-absorbing concrete.

6. The method for preparing concrete that moderates and absorbs neutrons according to claim 5, characterized in that, The stirring rate in step 1) is 30~60 r / min and the stirring time is 1~2 min; the stirring rate in step 2) is 30~60 r / min and the stirring time is 3~4 min; the stirring rate in step 3) is 120~180 r / min and the stirring time is 3~4 min.

7. The method for preparing concrete that moderates and absorbs neutrons according to claim 5, characterized in that, The curing conditions for the slowed-down and neutron-absorbing concrete are as follows: normal temperature curing before demolding after molding, and normal temperature curing with water sprayed to keep the surface moist for 7 days after demolding.

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