Impact-resistant concrete for compositely shielding gamma ray and neutron radiation and preparation method of impact-resistant concrete

Abstract

The invention discloses impact-resistant concrete for compositely shielding gamma ray and neutron radiation and a preparation method thereof, and belongs to the technical field of building materials. Comprising a binding material, 1500-2100 kg / m < 3 > of anti-radiation aggregate and 200-260 kg / m < 3 > of steel fiber, the anti-radiation aggregate is mechanical concrete prepared from one or more of selected magnetite aggregate, barite aggregate and hematite aggregate and B4C aggregate; the impact-resistant gamma-ray and neutron composite shielding UHPC material has good working performance, mechanical performance and durability while the dynamic impact performance, the gamma-ray shielding performance and the neutron shielding performance of the impact-resistant gamma-ray and neutron composite shielding UHPC material are improved, and the impact-resistant gamma-ray and neutron composite shielding UHPC material has important practical application value.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically a composite shielding gamma-ray and neutron radiation impact-resistant concrete and its preparation method. Background Technology

[0002] Nuclear technology is widely used in industries such as medicine, scientific research, and power. While creating economic and social benefits for humanity, it also poses many potential threats. Nuclear reactors and other radiation sources inevitably release various types of high-energy radiation during operation, harming the environment and human health. Gamma rays and neutron fluxes, in particular, have strong penetrating power, making shielding against these types of ionizing radiation especially important. To date, the main shielding materials used for various types of radiation include lead plates, iron / steel plates, glass / ceramics, polymers, water, and concrete. Radiation-shielding concrete is currently the most widely used and economical nuclear radiation protection material. Compared to metals and other shielding materials, it has advantages such as a wide availability of raw materials, ease of construction, and low manufacturing costs, and is widely used in structures such as nuclear power plant containment vessels and the protection of accelerators and radiochemical devices.

[0003] Radiation-shielding concrete, as a primary structural material in nuclear engineering construction, serves both to shield radiation and as a crucial safety guarantee for nuclear facilities; its mechanical properties are critical to the safety of the entire nuclear project. However, the design strength of existing radiation-shielding concrete is generally low, with most not exceeding C60, making it insufficient to withstand explosive impact loads or high-intensity dynamic loads caused by major geological disasters, posing safety hazards to nuclear engineering projects. Furthermore, with the aging of medical radiology buildings, some early-built radiation shielding walls require repair and reinforcement. If existing radiation-shielding concrete (with low mechanical properties) is used, increasing the wall thickness to achieve reinforcement results would necessitate a large increase in usable floor space. Therefore, there is an urgent need to develop high-strength, impact-resistant radiation-shielding concrete to meet the critical strategic needs of national defense and civilian nuclear engineering safety protection in my country. Ultra-high performance concrete (UHPC), with its high density, ultra-high strength, high toughness, and high impact resistance, is an ideal material for constructing ultra-high-strength, impact-resistant radiation shielding buildings. Summary of the Invention

[0004] This invention overcomes the shortcomings of existing technologies and proposes a composite shielding gamma-ray and neutron radiation impact-resistant concrete and its preparation method. This invention is achieved through the following technical solution: A composite shielding gamma-ray and neutron radiation impact-resistant concrete, comprising cementitious materials and radiation-shielding aggregates of 1500~2100 kg / m³. 3 Steel fiber 200~260 kg / m 3The radiation-shielding aggregate is one or more of selected magnetite aggregate, barite aggregate and hematite aggregate, combined with B4C aggregate in mechanical concrete.

[0005] Preferably, it also includes ≤50 kg / m 3 The neutron shielding functional component is a mechanical mixture of one or more of the following: calcium borate powder, B4C powder, B2O3 powder, and borax, with Li2CO3.

[0006] Preferably, it also includes ≤15 kg / m 3 CaCO3 whiskers.

[0007] Preferably, the steel fiber is a single copper-plated steel fiber or a mixture of copper-plated steel fibers with different aspect ratios and multi-anchor steel fibers.

[0008] Preferably, the copper-plated steel fiber has a nominal length of 12-23 mm, an equivalent diameter of 0.20-0.25 mm, a tensile strength ≥2000 MPa, and an elastic modulus of 200-220 GPa. The multi-anchor steel fiber has a nominal length of 20-30 mm, an equivalent diameter of 0.30-0.40 mm, a tensile strength ≥1000 MPa, and an elastic modulus of 210-230 GPa.

[0009] Preferably, the cementitious material includes: cement 550~700 kg / m³ 3 Fly ash microspheres 120~150 kg / m³ 3 Silica fume 120~150 kg / m³ 3 Expanding agent 50~80 kg / m 3 .

[0010] Preferably, the fly ash microspheres have a 28-day activity index > 110%, a water requirement ratio of 102%, and a spherical particle volume fraction ≥ 95%. The silica fume has a SiO2 mass content ≥ 95% and a specific surface area ≥ 18000 m². 2 / kg, 28-day activity index ≥100%.

[0011] Preferably, the cement is P·O 52.5 or P·II 52.5 type silicate cement.

[0012] Preferably, it also includes 15~30 kg / m³ of polycarboxylate superplasticizer. 3 Mixed with water 170~220 kg / m 3 The water used is ordinary tap water, which meets the requirements of the "Standard for Water Used in Concrete" JGJ63.

[0013] Preferably, the B4C aggregate B4C particles have a particle size of 1~3 mm and a B element content of ≥75%, wherein...10 Boron (B) accounts for 20% of the total boron content, has a Mohs hardness of 9.5, and an apparent density of 2500 kg / m³. 3 .

[0014] The apparent density of the selected magnetite aggregate is 6040 kg / m³. 3 It has a fineness modulus of 3.1 and an Fe2O3 content of >75%.

[0015] The apparent density of the barite aggregate is 3620 kg / m³. 3 It has a fineness modulus of 2.5 and a BaSO4 content of >65%.

[0016] The apparent density of the hematite aggregate is 4970 kg / m³. 3 It has a fineness modulus of 3.4 and an Fe2O3 content of >40%.

[0017] The apparent density of the CaCO3 whiskers is 2800 kg / m³. 3 It has a diameter of 0.5~2 μm, a length of 10~20 μm, an elastic modulus of 410~710 GPa, and a tensile strength of 3~6 GPa.

[0018] The water-reducing agent is a UHPC-specific polycarboxylate high-efficiency water-reducing agent with a solid content of 40% and a water reduction rate of 25%.

[0019] The expanding agent is a CaO-MgO composite expanding agent with a specific surface area of ​​330 m². 2 / kg, with a 7-day limiting swelling rate of 0.065% in water.

[0020] The method for preparing impact-resistant concrete that provides composite shielding against gamma rays and neutron radiation is characterized by comprising the following steps: S1. Weigh each raw material according to the proportions; S2. Add cementitious materials, radiation-shielding aggregates, and CaCO3 whiskers to a concrete mixer and premix for 1-3 minutes until homogeneous. Then, pour in 70%-90% water and polycarboxylate superplasticizer and wet mix for 3-5 minutes. Next, sprinkle in steel fibers and mix evenly. Add the remaining water and neutron shielding components to the mixer and mix for another 1-3 minutes until homogeneous. After molding, vibration, and shaping, cover the surface with a waterproof film for film curing. After demolding, finally perform standard curing or steam curing until the specified age.

[0021] The apparent density of the impact-resistant gamma-ray and neutron composite shielded ultra-high performance concrete obtained by this invention is 3200~3500 kg / m³. 3Meanwhile, its compressive strength can reach C100 or higher, and it has good workability, durability and volume stability. It can effectively improve the dynamic impact performance, gamma-ray shielding performance and fast neutron shielding performance of concrete components, and has important practical application value.

[0022] The principle employed in this invention is as follows: 1. This invention uses radiation-shielding aggregates as fine aggregates to prepare ultra-high performance concrete (UHPC). The main purpose is to introduce a large amount of high atomic number elements such as Fe and Ba into the UHPC material system. The introduction of these heavy elements can significantly increase the apparent density of UHPC, enhancing the energy loss of UHPC materials during photoelectric effect, Compton scattering, and pair emission of incident gamma rays. In other words, the large-scale introduction of heavy elements increases the interaction cross-section of gamma rays in UHPC during these processes. Therefore, the presence of gamma-ray shielding aggregates and gamma-ray shielding cementitious components improves the gamma-ray shielding performance of the UHPC material. Furthermore, the Fe element in the steel fibers also plays a positive role in improving the apparent density and gamma-ray shielding performance of the UHPC material.

[0023] 2. Besides shielding gamma rays, high atomic number elements such as Fe and Ba in the radiation-shielding aggregates and steel fibers can also rapidly reduce the energy of fast neutrons through inelastic collisions. Since the rest mass of a neutron is the same as that of hydrogen, a single head-on collision with hydrogen can result in the loss of all energy. Therefore, hard borate powder and borax containing water of crystallization are introduced into the UHPC system. This water of crystallization, along with gel water and free water in the slurry, further reduces the energy of neutrons slowed down by heavy elements. After inelastic and elastic scattering, fast neutrons decrease in energy until they become slow neutrons, which require absorption to completely disappear. The neutron shielding components introduced... 1 H, 7 Li, 10 Elements such as boron have large neutron capture cross sections and are good neutron absorbers.

[0024] 3. This invention employs various types of hybrid steel fibers and CaCO3 whiskers as reinforcing and toughening components for UHPC materials, primarily to improve the dynamic impact performance of UHPC materials under high-speed impact. The steel fibers with smaller aspect ratios are numerous and closely spaced, mainly responsible for reinforcing the matrix and suppressing the initiation and early development of microcracks; the steel fibers with larger aspect ratios are mainly responsible for bridging macroscopic cracks that have already expanded, providing a higher later-stage toughening effect; the multi-anchor steel fibers achieve more efficient and durable mechanical interlocking through end anchors. When cracks open and fibers begin to be pulled out of the matrix, the end anchors strongly interlock with the surrounding matrix material, thus enabling the fiber and matrix to share the force, thereby achieving passive dissipation of impact energy; while the diameter and length of the CaCO3 whiskers are 0.5~2 μm and 10~20 μm, respectively. μm can achieve crack prevention and reinforcement of UHPC cement paste at the micron scale. It dissipates a large amount of fracture energy through whisker pull-out and crack deflection. At the same time, the uniformly dispersed CaCO3 whiskers can not only fill the micropores in the cement matrix, making the matrix more compact, but also serve as nucleation points for heterogeneous nucleation of slurry hydration products, promoting the hydration of cementitious materials and optimizing the structure of the interface transition zone.

[0025] This invention selects silica fume and fly ash microspheres as mineral admixtures, which work together with additives to regulate the workability of UHPC materials. Silica fume contains a large amount of amorphous SiO2, which has a high viscous resistance, significantly improving the segregation and bleeding of fresh concrete and increasing the viscosity of UHPC materials. The ball-bead effect, filling and water-reducing properties of fly ash microspheres not only effectively improve the fluidity and homogeneity of fresh concrete, but also fill the voids in UHPC, enhancing the density of the cementitious paste and improving the mechanical and durability properties of concrete. The introduction of water-reducing agents not only reduces the water-cement ratio of UHPC materials and improves their mechanical properties, but also effectively regulates their workability. The neutron shielding functional component not only regulates the workability of UHPC materials, but also controls their setting time.

[0026] The beneficial effects of this invention compared to the prior art are as follows: 1. This invention uses radiation-shielding aggregates as fine aggregates and replaces part of the cementitious materials with neutron-shielding functional components to prepare impact-resistant gamma-ray and neutron-shielded composite ultra-high performance concrete. The magnetite, barite, and hematite aggregates in the radiation-shielding aggregates contain a large proportion of heavy elements such as Fe and Ba, and a large amount of Fe can also be introduced into the UHPC system from the steel fibers. These heavy elements not only enhance its gamma-ray shielding ability but also undergo inelastic scattering with fast neutrons, reducing their energy (down to medium-energy neutrons). The gel water in the CSH gel after cementitious slurry hydration, the crystal water in crystals such as Ca(OH)2 and AFt, and the free water in the pores that has not participated in hydration can undergo elastic scattering with the neutrons attenuated by the heavy elements, further reducing their energy (down to thermal neutrons). The introduction of neutron-shielding functional components... 1 H, 7 Li, 10 Neutron-absorbing components such as B can absorb thermal neutrons, further reducing their harmful effects. By optimizing the proportions of cementitious materials, aggregates, and fibers in UHPC, the prepared UHPC material exhibits... 60 Co-source gamma-ray shielding performance can be improved by up to 30% compared to ordinary quartz sand UHPC, and its DT-source fast neutron shielding capability can be improved by up to 40% or more.

[0027] 2. This invention uses various types of hybrid steel fibers and CaCO3 whiskers as toughening and crack-resistant components for UHPC materials. By designing different types of steel fibers and CaCO3 whiskers in the UHPC mix proportion, the aim is to maximize the crack-resistant effect of different toughening and crack-resistant components, suppress the initiation and propagation of cracks in UHPC materials under high-speed impact, and thus improve the dynamic compressive strength and impact toughness of UHPC materials. Regarding the roles of different types of steel fibers and CaCO3 whiskers in UHPC materials, specifically, when crack initiation or microcracks are small, steel fibers with smaller aspect ratios inhibit the initiation and early development of microcracks; when cracks extend to a certain size, steel fibers with larger aspect ratios bridge the extending cracks; the mechanical interlocking between the anchor points of multi-anchored steel fibers and the matrix achieves synergistic stress between the matrix and fibers, reducing the probability of steel fiber pull-out under impact; in addition, CaCO3 whiskers can also achieve crack prevention and reinforcement of UHPC cementitious slurry at the micron scale, dissipating a large amount of fracture energy through whisker pull-out and crack deflection. At the same time, uniformly dispersed CaCO3 whiskers can not only fill the micropores in the cement matrix, making the matrix more compact, but also serve as nucleation sites for heterogeneous nucleation of slurry hydration products, promoting the hydration of cementitious materials and optimizing the structure of the interface transition zone.

[0028] 3. The apparent density of the impact-resistant gamma-ray and neutron composite shielding ultra-high performance concrete obtained by this invention is 3200~3500 kg / m³.3 Meanwhile, the compressive strength grade can reach C100 or above, and it has good working performance, mechanical properties and volume stability. It can effectively improve the toughness, impact resistance, durability, gamma-ray and fast neutron shielding performance of UHPC components, and has important practical application value. Detailed Implementation

[0029] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solution of the present invention will be described in detail below with reference to embodiments, but the scope of protection is not limited thereto.

[0030] The following comparative examples and embodiments: The cement used is P.Ⅱ 52.5 type Portland cement produced by Hubei Waishi Cement, with an apparent density of 3.16 g / cm³. 3 Specific surface area is 340 kg / m² 3 ; The fly ash microspheres had a 28-day activity index of 113%, a water requirement ratio of 102%, and were amorphous. They were provided by Tianjin Zhucheng New Material Technology Co., Ltd. The specific surface area of ​​silica fume is 18300 m². 2 / kg, SiO2 mass content is 94%, and 28-day activity index is 105%; The neutron shielding functional component is a mechanical mixture of one or more of the following: borosilicate powder, B4C powder, B2O3 powder, and borax, with Li2CO3. Among them, B2O3, borax, and Li2CO3 are all chemically analytical grade produced by Sinopharm Group, the purity of B4C powder is as high as 99.9%, and the crystal water content of borosilicate powder is 23.54%. The expanding agent is a CaO-MgO composite expanding agent produced by a company in Wuhan, with a specific surface area of ​​330 m². 2 / kg, the limiting swelling rate in water over 7 days is 0.065%; The B4C aggregate in the radiation shielding aggregate is high-purity B4C particles produced in Xingtai, Hebei Province, with a particle size of 1~3 mm and a B content ≥75%. 10 Boron (B) accounts for 20% of the total boron content, has a Mohs hardness of 9.5, and an apparent density of 2500 kg / m³. 3 Magnetite, barite, and hematite are all found in Lingshou County, Hebei Province, with apparent densities of 6040 kg / m³. 3 3620 kg / m 3 and 4970 kg / m 3 ; There are three main types of steel fibers. Type I copper-plated steel fibers have a nominal length of 13 mm, an equivalent diameter of 0.25 mm, and a tensile strength of over 2200 MPa. Type II copper-plated steel fibers have a nominal length of 22 mm, an equivalent diameter of 0.20 mm, and a tensile strength of over 2000 MPa. Multi-anchor steel fibers (Type III) have a nominal length of 25 mm, an equivalent diameter of 0.35 mm, and a tensile strength of over 1000 MPa. CaCO3 whiskers, produced by a company in Hebei Province, are a micron-sized fibrous inorganic filler material with an apparent density of 2800 kg / m³. 3 The diameter and length are 0.5~2 μm and 10~20 μm, respectively, the elastic modulus can reach 410~710 GPa, and the tensile strength can reach 3~6 GPa; The water-reducing agent is a UHPC-specific polycarboxylate high-efficiency water-reducing agent produced by a company in Wuhan, with a solid content of 40% and a water reduction rate of 25%; the water is ordinary tap water. Example 1

[0031] This embodiment proposes a composite shielding gamma-ray and neutron radiation impact-resistant concrete. The raw material mix proportions are shown in Table 1. ; Example 1 uses cement, silica fume, fly ash microspheres, and an expanding agent as cementitious materials, and radiation-shielding aggregate as fine aggregate. Specifically, the radiation-shielding aggregate in this example is a mechanically prepared concrete composed of selected magnetite aggregate and B4C aggregate, with a volume ratio of 2:1. The radiation-shielding aggregate needs to be soaked in clean water for at least 24 hours until it reaches a saturated surface-dry state. Furthermore, the steel fibers used in Example 1 are type I copper-plated steel fibers. Example 2

[0032] This embodiment proposes a composite shielding gamma-ray and neutron radiation impact-resistant concrete. The raw material mix proportions are shown in Table 2. ; Example 2 uses radiation-shielding aggregate as fine aggregate. In this example, the radiation-shielding aggregate is specifically: mechanical concrete of barite and B4C aggregate, with a volume ratio of barite to B4C aggregate of 3:1. The volume of the radiation-shielding aggregate in this example is the same as that in Example 1. In this embodiment, the neutron shielding functional component is used to replace 5% of the cementitious material by mass in Example 1. Furthermore, the steel fiber used in Example 2 is Type I copper-plated steel fiber. Example 3

[0033] This embodiment proposes a composite shielding gamma-ray and neutron radiation impact-resistant concrete. The raw material mix proportions are shown in Table 3. ; The fine aggregate and cementitious material used in this embodiment are the same as in Example 2. Unlike Example 2, the steel fibers used in Example 3 are a mixture of Type I, Type II, and Type III steel fibers in a mass ratio of 10:4:12. Furthermore, to further improve the toughness of the prepared UHPC material, Example 3 also incorporates 0.5% CaCO3 whiskers by mass into the mix proportion.

[0034] Comparative Example The comparative example was used to compare with Examples 1-3. To ensure the reliability of the comparison results, the amounts of cementitious materials, water, and water-reducing agent in the comparative example were kept consistent with those in Example 1. The difference was that the comparative example used conventional silica sand as the fine aggregate, and the amount of silica sand was ensured to be an equal volume replacement of the radiation-shielding aggregate in Examples 1-3. Consistent with Examples 1-2, the comparative example also used 2.5% by volume of Type I copper-plated steel fiber as the toughening component. Specific mix proportions are shown in Table 4. ; Example 4

[0035] A preparation technique for impact-resistant concrete that provides composite shielding against gamma rays and neutron radiation is provided. Taking the composition of Example 3 as an example, the preparation steps are as follows: 1) Weigh each raw material according to the proportions described in Table 3; 2) Add the cementitious materials, including the expansion agent, CaCO3 whiskers, and radiation-shielding aggregate to the concrete mixer and premix for 3 minutes until visually uniform. Then, pour in 80% water and polycarboxylate superplasticizer and wet mix for 5 minutes. Finally, sprinkle in the steel fiber and mix evenly. Add the remaining water and neutron shielding functional components to the slurry and mix for 5 minutes until uniform. After molding, vibration, and shaping, cover the surface with a waterproof film for film curing, then remove the mold. Finally, perform standard curing until the specified age to obtain the impact-resistant gamma-ray and neutron composite shielding ultra-high performance concrete.

[0036] Concrete was prepared using the raw materials of the comparative example and Examples 1-2 according to the above preparation method; the performance test results of the impact-resistant gamma-ray and neutron composite shielded ultra-high performance concrete obtained by the comparative example and each example are shown in Table 5-8.

[0037] ; ; ; ; The above results indicate that, compared to the comparative example, the working performance of the UHPC material obtained in Example 1 was improved, while the working performance of the UHPC materials obtained in Examples 2-3 was reduced to varying degrees. Compared to working performance, the apparent density of the UHPC materials obtained in Examples 1-3 was improved. The apparent density, 28-day compressive strength, and 28-day flexural strength of Example 3 were increased by 35.92%, 21.63%, and 12.67% respectively compared to the comparative example.

[0038] Compared to the comparative example, the gamma-ray shielding performance of Example 1 was improved by 5.55%, while the gamma-ray shielding performance of Examples 2 and 3 was improved by 29.09% and 30.29%, respectively. Compared to UHPC materials prepared from ordinary quartz sand, the UHPC material prepared from radiation-shielding aggregates and neutron-shielding functional components exhibits superior shielding performance. 60 When the Co-source gamma-ray dose reaches 90%, the sample thickness can be reduced by up to 3.76 cm.

[0039] Compared with the comparative examples, the fast neutron shielding performance of the DT source in Example 1 was improved by 19.72%, while the fast neutron shielding performance of Examples 2 and 3 was improved by 42.14% and 42.37%, respectively. For Example 3, when the UHPC sample thickness was 20 cm, it could shield neutron energies of 93.66%.

[0040] Compared with the comparative examples, the dynamic compressive strength and impact toughness of Examples 1 and 3 were improved to varying degrees. Compared with Example 2, which did not have a hybrid fiber design and did not contain CaCO3 whiskers, the dynamic compressive strength of Example 3 increased by 6.19%, the dynamic peak toughness increased by 61.12%, and the dynamic ultimate toughness increased by 25.16%.

[0041] In summary, the impact-resistant gamma-ray and neutron composite shielding ultra-high performance concrete obtained by this invention, especially the UHPC material obtained in Example 3, possesses excellent mechanical properties, dynamic impact resistance, and gamma-ray and neutron shielding performance. The apparent density of the obtained ultra-high performance concrete can reach up to 3330 kg / m³. 3 Compared to quartz sand UHPC, the weight of the resulting UHPC increases by more than 35%, and its 28-day compressive strength can reach over 140 MPa. Compared to quartz sand UHPC, the resulting impact-resistant γ-ray and neutron composite shielding UHPC material shows improvements of up to 30%, 40%, 30%, and 70% in γ-ray shielding performance, neutron shielding performance, dynamic compressive strength, and impact ultimate toughness, respectively.

[0042] This invention employs one or more selected magnetite, barite, and hematite aggregates, along with B4C aggregate, as the radiation-shielding aggregate for a composite gamma-ray and neutron shielding UHPC material. It utilizes one or more selected borosilicate powder, B4C powder, B2O3 powder, and borax, along with Li2CO3, as the neutron-shielding functional component. In the radiation-shielding aggregate, the selected magnetite, barite, and hematite introduce a large amount of heavy elements such as Fe and Ba. These elements not only react with… 60 Co-source gamma rays undergo Compton scattering and photoelectric absorption, effectively reducing the energy of incident gamma rays and thus endowing UHPC materials with excellent gamma-ray shielding performance. Simultaneously, they can undergo inelastic scattering with fast neutrons generated by DT sources, causing rapid energy decay of fast neutrons, even reducing their energy to the level of medium-energy neutrons. The hard borate powder and borax in the neutron shielding functional components contain a large amount of water of crystallization. The CSH gel and Ca(OH)2 crystals produced during the hydration of the cementitious materials also contain a considerable amount of gel water and water of crystallization. These chemically bound waters and the unhydrated free water in the cementitious slurry can undergo elastic scattering with medium-energy neutrons, further reducing their energy until they are reduced to thermal neutrons. Finally, the B4C aggregate in the radiation-shielding aggregate and the light elements such as B and Li introduced into the UHPC system by the neutron shielding functional components can absorb thermal neutrons, further reducing the harm caused by neutrons.

[0043] A hybrid of copper-plated steel fibers with different aspect ratios and multi-anchor steel fibers, incorporating CaCO3 whiskers, is used as a reinforcing and toughening material for impact-resistant and radiation-shielding UHPC. The hybrid fibers and CaCO3 whiskers enhance the dynamic impact performance of the UHPC material at different scales. The steric hindrance effect of polycarboxylate superplasticizer and the "ball bearing effect" of fly ash microspheres are utilized to optimize the working performance and improve the density of the UHPC. An expanding agent is used to reduce the self-shrinkage and drying shrinkage of the UHPC, improving its volumetric stability. The impact-resistant gamma-ray and neutron composite shielding UHPC material described in this invention not only improves its dynamic impact performance, gamma-ray shielding performance, and neutron shielding performance, but also possesses good working performance, mechanical properties, and durability, making it of significant practical application value.

[0044] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0045] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this application and are not intended to limit the scope of protection of this application. All equivalent implementation methods or modifications made without departing from the spirit of the art of this application should be included within the scope of protection of this invention.

Claims

1. A composite shielding gamma-ray and neutron radiation impact-resistant concrete, characterized in that, Includes cementitious materials and radiation-shielding aggregates of 1500~2100 kg / m³ 3 Steel fiber 200~260 kg / m 3 The radiation-shielding aggregate is one or more of selected magnetite aggregate, barite aggregate and hematite aggregate, combined with B4C aggregate in mechanical concrete.

2. The impact-resistant concrete with composite shielding against gamma rays and neutron radiation according to claim 1, characterized in that, Also includes ≤50 kg / m 3 The neutron shielding functional component is a mechanical mixture of one or more of the following: calcium borate powder, B4C powder, B2O3 powder, and borax, with Li2CO3.

3. The impact-resistant concrete with composite shielding against gamma rays and neutron radiation according to claim 2, characterized in that, Also includes ≤15 kg / m 3 CaCO3 whiskers.

4. The impact-resistant concrete with composite shielding against gamma rays and neutron radiation according to claim 1, characterized in that, The steel fiber is a single copper-plated steel fiber or a mixture of copper-plated steel fibers with different aspect ratios and multi-anchor steel fibers.

5. The impact-resistant concrete with composite shielding against gamma rays and neutron radiation according to claim 1, characterized in that, Cementitious materials include: cement 550~700 kg / m³ 3 Fly ash microspheres 120~150 kg / m³ 3 Silica fume 120~150 kg / m³ 3 Expanding agent 50~80 kg / m 3 .

6. The impact-resistant concrete for composite shielding against gamma rays and neutron radiation according to claim 5, characterized in that, The fly ash microspheres have a 28-day activity index >110%, a water requirement ratio of 102%, and a spherical particle volume fraction ≥95%.

7. The impact-resistant concrete with composite shielding against gamma rays and neutron radiation according to claim 5, characterized in that, The cement is P·O 52.5 or P·II 52.5 type silicate cement.

8. The impact-resistant concrete with composite shielding against gamma rays and neutron radiation according to claim 1, characterized in that, It also includes polycarboxylate superplasticizer at 15~30 kg / m² 3 Mixed with water 170~220 kg / m 3 .

9. The impact-resistant concrete for composite shielding against gamma rays and neutron radiation according to claim 1, characterized in that, The B4C aggregate, consisting of B4C particles with a particle size of 1-3 mm and a B element content ≥75%, contains... 10 Boron (B) accounts for 20% of the total boron content, has a Mohs hardness of 9.5, and an apparent density of 2500 kg / m³. 3 .

10. A method for preparing impact-resistant concrete with composite shielding against gamma rays and neutron radiation according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Weigh each raw material according to the proportions; S2. Add cementitious materials, radiation-shielding aggregates, and CaCO3 whiskers to a concrete mixer and premix for 1-3 minutes until homogeneous. Then, pour in 70%-90% water and polycarboxylate superplasticizer and wet mix for 3-5 minutes. Next, sprinkle in steel fibers and mix evenly. Add the remaining water and neutron shielding components to the mixer and mix for another 1-3 minutes until homogeneous. After molding, vibration, and shaping, cover the surface with a waterproof film for film curing. After demolding, finally perform standard curing or steam curing until the specified age.