A kind of anti-γ-ray ultra-high performance concrete based on radiation-proof functional aggregates and its preparation method

Abstract

The present invention provides a γ-ray shielding ultra-high performance concrete based on radiation-proof functional aggregates and a preparation method thereof. The radiation-proof functional aggregates of the present invention can, on the one hand, effectively increase the content of heavy elements such as Pb and Ba in the UHPC material and improve the γ-ray shielding performance of the UHPC material; on the other hand, the outer shell structure of the radiation-proof functional aggregates has a large number of fine and interconnected pores. This structure not only improves the bonding strength between the radiation-proof functional aggregates and the cement mortar, but also the radiation-proof functional aggregates have an internal curing effect. The pre-wetted radiation-proof functional aggregates after soaking in clean water will slowly release the internal water over time after the concrete is formed, enabling the concrete to be fully internally cured, greatly reducing the autogenous shrinkage and drying shrinkage of the concrete, and at the same time improving the compactness and strength of the concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly to a γ-ray resistant ultra-high performance concrete based on radiation protection functional aggregates and a preparation method thereof. Background Art

[0002] Radiation protection concrete is currently the most widely used and economical nuclear radiation protection material. Compared with metal and organic polymer protection materials, it has the advantages of wide raw material sources, convenient construction, and low manufacturing cost, and is widely used in structures such as nuclear power generation pressure vessels, accelerators, and radiochemical device protection.

[0003] As the main structural material of nuclear engineering buildings, radiation protection concrete not only undertakes the task of shielding rays but also is an important safety guarantee for nuclear facilities. Its mechanical properties are related to the safety of the entire nuclear project. However, the design strength of currently existing radiation protection concrete is generally not high, and most do not exceed C60, making it difficult to resist explosion shock loads or high-intensity dynamic loads caused by major geological disasters, leaving potential safety hazards for nuclear projects. In addition, with the aging of medical radiology department buildings, some early-built ray shielding walls need to be repaired and strengthened. If the existing radiation protection concrete (with low mechanical properties) is used, only by increasing the thickness of the shielding wall can the reinforcement effect be achieved, resulting in a large amount of indoor area being occupied by the reinforced wall. Therefore, there is an urgent need to develop concrete with high strength, excellent impact resistance, and radiation protection performance to meet the major strategic needs of national defense and civilian nuclear engineering safety protection in China. Summary of the Invention

[0004] In view of this, the present invention provides a γ-ray resistant ultra-high performance concrete based on radiation protection functional aggregates and a preparation method thereof to solve or partially solve the technical problems existing in the prior art.

[0005] In the first aspect, the present invention provides a radiation protection functional aggregate, which includes a core layer and a shell layer coated outside the core layer. Among them, the core layer includes the following raw materials: lead powder, barite powder, and a cementitious material. The cementitious material includes portland cement and granulated blast furnace slag. The mass ratio of the lead powder, barite powder, and cementitious material is (10 - 50):(30 - 70):(10 - 25); the shell layer is γ-C2S after carbonization.

[0006] Preferably, for the radiation protection functional aggregate, the diameter of the core layer is 3 - 8 mm, and the diameter of the radiation protection functional aggregate is 5 - 10 mm.

[0007] In the second aspect, the present invention also provides a preparation method of the radiation protection functional aggregate, including the following steps:

[0008] Mix lead powder, barite powder and gelling material, then stir, add water and granulate to obtain the first green body.

[0009] Cure the first green body and then place it under autoclave curing conditions at a temperature of 200 - 220 °C and a pressure of 0.5 - 2 MPa for 6 - 8 h to form, thus obtaining the core layer.

[0010] Mix γ-C2S, water and pore-forming agent, then stir to obtain a gelling slurry.

[0011] Place the core layer in the gelling slurry for secondary granulation to obtain the second green body, so that the surface of the core layer is covered with the shell layer gelling slurry, and then place the second green body in a carbonization device for carbonization for 1 - 3 h to obtain the radiation-proof functional aggregate.

[0012] Thirdly, the present invention also provides a γ-ray-proof ultra-high performance concrete, comprising the following raw materials: 700 - 900 kg / m 3 , fly ash microspheres 150 - 250 kg / m 3 , silica fume 150 - 250 kg / m 3 , radiation-proof functional aggregate 500 - 1500 kg / m 3 , copper-plated steel fibers 100 - 250 kg / m 3 , water reducer 20 - 35 kg / m 3 , expansive agent 60 - 85 kg / m 3 , water 170 - 220 kg / m 3 ;

[0013] Among them, the radiation-proof functional aggregate is the above-mentioned radiation-proof functional aggregate.

[0014] Preferably, for the γ-ray-proof ultra-high performance concrete, the cement is P·O52.5 or P·II 52.5 Portland cement.

[0015] Preferably, for the γ-ray-proof ultra-high performance concrete, the loss on ignition of the fly ash microspheres ≤ 5.0%, the water demand ratio ≤ 90%, and the spherical particle volume ratio ≥ 95%.

[0016] Preferably, for the γ-ray-proof ultra-high performance concrete, the mass content of SiO2 in the silica fume ≥ 95%, the specific surface area ≥ 15500 m 2 / kg, and the 28-day activity index ≥ 100%.

[0017] Preferably, for the γ-ray-proof ultra-high performance concrete, the fracture strength of the copper-plated steel fibers ≥ 3000 MPa, and the elastic modulus is 40 - 60 GPa.

[0018] Preferably, for the γ-ray-proof ultra-high performance concrete, the water reducer is a polycarboxylate water reducer.

[0019] In a fourth aspect, the present invention also provides a method for preparing the anti-γ-ray ultra-high performance concrete as described above, comprising the following steps:

[0020] Soak the radiation-proof functional aggregate in water until it reaches a saturated water state;

[0021] Then mix and stir the soaked radiation-proof functional aggregate, cement, silica fume, fly ash microspheres, and expansive agent, then add water and a water reducer and stir again. Finally, add copper-plated steel fibers and continue to stir evenly. After molding, vibrating, and forming, perform film curing, then remove the mold, and finally perform standard curing or steam curing to obtain the anti-γ-ray ultra-high performance concrete.

[0022] The radiation-proof functional aggregate, the anti-γ-ray ultra-high performance concrete, and the method for preparing the same of the present invention have the following beneficial effects compared with the prior art:

[0023] 1. For the radiation-proof functional aggregate of the present invention, on the one hand, it can effectively increase the content of heavy elements such as Pb and Ba in the UHPC material and improve the γ-ray shielding performance of the UHPC material; on the other hand, the outer shell structure of the radiation-proof functional aggregate has a large number of fine and interconnected pores. This structure not only improves the bonding strength between the radiation-proof functional aggregate and the cement mortar, but also the radiation-proof functional aggregate has an internal curing effect. The pre-wetted radiation-proof functional aggregate after soaking in clean water will slowly release the internal water over time after the concrete is formed, enabling the concrete to be fully internally cured, greatly reducing the autogenous shrinkage and drying shrinkage of the concrete, and at the same time improving the compactness and strength of the concrete.

[0024] 2. The preparation method of the γ-ray resistant ultra-high performance concrete of the present invention prepares ultra-high performance concrete by using pre-wetted radiation protection functional aggregates. The internal curing effect can improve the problem of large shrinkage of current ultra-high performance concrete to a certain extent. At the same time, the premixing process is combined to promote the formation of a high-strength and dense interfacial transition zone around the radiation protection functional aggregates, improving the mechanical properties and durability of the radiation protection ultra-high performance concrete. In addition, it can effectively solve the problems of shortage of radiation protection aggregates in the current market, insufficient radiation protection effect of natural radiation protection aggregates, and low crushing value. The preparation method of this application uses mineral admixtures such as polycarboxylate water reducer and fly ash microspheres to optimize the workability of the concrete mixture, improve the compactness and homogeneity of the concrete, and further reduce the shrinkage of the concrete, improving the mechanical properties and volume stability of the lightweight ultra-high performance concrete. This application combines the expansion agent to compensate for shrinkage and the internal curing effect of the pre-wetted radiation protection functional aggregates to effectively improve the crack resistance and volume stability of the ultra-high performance concrete. At the same time, it can optimize the pore structure of the concrete and improve the durability of the concrete. The total content of Ba element and Pb element in the radiation protection functional aggregates used in this application accounts for more than 40% of the total element content of the aggregates. The incorporation of the radiation protection functional aggregates can effectively improve the γ-ray radiation resistance of UHPC. The apparent density of the radiation protection ultra-high performance concrete prepared in this application is 2500~2800kg / m 3 , and the compressive strength grade can reach above C100 at the same time, and it has good workability, mechanical properties and volume stability, which can effectively improve the toughness, impact resistance, durability and γ-ray radiation resistance of concrete components, and has important practical application value. Specific Embodiments

[0025] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] The embodiment of this application provides a radiation protection functional aggregate, which is composed of an internal core layer and a shell layer coated outside the core layer. Among them, the core layer includes the following raw materials: lead powder, barite powder, and cementitious material. The cementitious material includes Portland cement and granulated blast furnace slag. The mass ratio of lead powder, barite powder, and cementitious material is (10~50):(30~70):(10~25); the shell layer is γ-C2S after carbonization.

[0027] In some embodiments, the diameter of the core layer is 3~8mm, and the diameter of the radiation protection functional aggregate is 5~10mm.

[0028] It should be noted that the radiation-proof functional aggregate of the present application is a non-fired spherical aggregate with a core-shell structure, which consists of two parts: a core layer and a shell layer, and its apparent density is 2500 kg / m 3 , and the saturated surface dry water absorption rate is 5% - 15%.

[0029] In some embodiments, the mass ratio of portland cement to granulated blast furnace slag in the cementitious material is: (60 - 80):(20 - 40).

[0030] Based on the same inventive concept, the embodiment of the present application also provides a preparation method of the radiation-proof functional aggregate, including the following steps:

[0031] S1. Mix lead powder, barite powder and cementitious material, stir, then add water and granulate to obtain a first green body;

[0032] S2. Cure the green body and then place it under autoclave curing conditions at a temperature of 200 - 220 °C and a pressure of 0.5 - 2 MPa for 6 - 8 h to form, thus obtaining the core layer;

[0033] S3. Mix γ-C2S, water and pore-forming agent, and stir to obtain a cementitious slurry;

[0034] S4. Place the core layer in the cementitious slurry formed in S3 for secondary granulation to obtain a second green body, so that the surface of the core layer is covered with the shell layer cementitious slurry, and then place the second green body in a carbonization device for carbonization for 1 - 3 h, thus obtaining the radiation-proof functional aggregate.

[0035] Specifically, in step S1, lead powder, barite powder and cementitious material are mixed and stirred, then water is added and granulated to obtain a first green body, and the particle size of the first green body is controlled to be less than 4.75 mm; among them, the mass of water is 5% - 9% of the sum of the masses of lead powder, barite powder and cementitious material.

[0036] In step S3, the mass of the pore-forming agent is 3% - 8% of the sum of the masses of γ-C2S and the pore-forming agent; γ-C2S, water and the pore-forming agent are mixed and stirred, and among them, the mass of water is 5% - 9% of the sum of the masses of γ-C2S and the pore-forming agent.

[0037] Specifically, γ-C2S is prepared by a conventional method. Specifically, CaCO3 and SiO2 are mixed according to the composition of C2S and then calcined to obtain.

[0038] The pore-forming agent includes a mixture of CaCO3 and MgCO3, and among them, the mass ratio of CaCO3 to MgCO3 is (1 - 3):(1 - 3). Based on the same inventive concept, the embodiment of the present application also provides a γ-ray-proof ultra-high performance concrete, including the following raw materials: cement 700 - 900 kg / m 3 , fly ash cenosphere 150 - 250 kg / m 3, silica fume 150 - 250 kg / m 3 , radiation - proof functional aggregate 500 - 1500 kg / m 3 , copper - plated steel fiber 100 - 250 kg / m 3 , water - reducing agent 20 - 35 kg / m 3 , expansive agent 60 - 85 kg / m 3 , water 170 - 220 kg / m 3 ;

[0039] Among them, the radiation - proof functional aggregate is the aforementioned radiation - proof functional aggregate.

[0040] This application uses radiation - proof functional aggregate to prepare γ - ray radiation - proof ultra - high - performance concrete. On the one hand, it can effectively increase the content of heavy elements such as Pb and Ba in UHPC materials and improve the γ - ray shielding performance of UHPC materials; on the other hand, the shell structure of the radiation - proof functional aggregate has a large number of fine and interconnected pores. This structure not only improves the bonding strength between the radiation - proof functional aggregate and cement mortar, but also the radiation - proof functional aggregate has an internal curing effect. The pre - wetted radiation - proof functional aggregate after soaking in clean water will slowly release the internal water over time after the concrete is formed, enabling the concrete to be fully internally cured, greatly reducing the autogenous shrinkage and drying shrinkage of the concrete, and at the same time improving the compactness and strength of the concrete. In addition, during the concrete preparation process, coating a layer of cement and silica fume on the surface of the pre - wetted radiation - proof functional aggregate in advance can form a high - strength and dense interfacial zone at the junction of the radiation - proof functional aggregate and the cementitious paste, improving the interfacial bonding strength between the cement paste and the radiation - proof functional aggregate, and preventing the migration of harmful ions in the capillary pores of the hardened paste, thus improving the mechanical properties and impermeability of the radiation - proof ultra - high - performance concrete.

[0041] In some embodiments, the cement is P·O52.5 or P·II 52.5 Portland cement.

[0042] In some embodiments, the loss on ignition of fly ash microspheres ≤5.0%, the water demand ratio ≤90%, and the spherical particle volume ratio ≥95%.

[0043] In some embodiments, the mass content of SiO2 in silica fume ≥95%, the specific surface area ≥15500 m 2 / kg, and the 28 - day activity index ≥100%.

[0044] In the above embodiments, the mass content of SiO2 in silica fume is above 95%, and the vast majority is amorphous SiO2, which has high pozzolanic activity. At the same time, the silica fume particles are mainly amorphous spherical particles with an average particle size in the range of 0.1 - 0.2 μm. The silica fume has a large viscous resistance, which significantly improves the segregation and bleeding of fresh concrete, but at the same time increases the viscosity of fresh concrete. In the present invention, by adding fly ash microspheres, the rolling effect, filling and water-reducing effects of the ultra-fine fly ash microspheres can be used to effectively improve the fluidity and homogeneity of fresh concrete, and at the same time can also fill and "refine" the voids and capillary pores in the concrete, improving the mechanical properties and durability of the concrete.

[0045] In some embodiments, the nominal length of the copper-plated steel fiber is 10 - 16 mm, the equivalent diameter is 0.18 - 0.35 mm, the fracture strength ≥ 3000 MPa, and the elastic modulus is 40 - 60 GPa.

[0046] In some embodiments, the water-reducing agent is a polycarboxylate water-reducing agent.

[0047] In some embodiments, the water used is ordinary tap water, which meets the requirements of the "Standard for Concrete Water" JGJ63.

[0048] Based on the same inventive concept, the embodiments of the present application also provide a preparation method for γ-ray-proof ultra-high performance concrete, including the following steps:

[0049] S1. Soak the radiation-proof functional aggregate in water until it reaches a saturated water state;

[0050] S2. Then mix and stir the soaked radiation-proof functional aggregate, cement, silica fume, fly ash microspheres, and expansive agent, then add water and a water-reducing agent and stir again. Finally, add the copper-plated steel fiber and continue to stir evenly. After molding, vibration, and forming, carry out film curing, then remove the mold, and finally carry out standard curing or steam curing to obtain the γ-ray-proof ultra-high performance concrete.

[0051] Specifically, in some embodiments, the soaked radiation-proof functional aggregate, cement, silica fume, fly ash microspheres, and expansive agent are added to a concrete mixer and pre-mixed for 1 - 3 min, then 70% - 90% of the mass of water and the water-reducing agent are added and stirred again for 3 - 5 min. Finally, after adding the copper-plated steel fiber, the remaining water is added and stirred evenly. After molding, vibration, and forming, carry out film curing, then remove the mold, and finally carry out standard curing or steam curing to the specified age to obtain the γ-ray-proof ultra-high performance concrete.

[0052] The preparation method of the γ-ray-proof ultra-high performance concrete of the present application can improve the problem of large shrinkage of the current ultra-high performance concrete to a certain extent by using pre-wetted radiation-proof functional aggregates to prepare ultra-high performance concrete, and at the same time, combining with the premixing process to promote the formation of a high-strength and dense interfacial transition zone around the radiation-proof functional aggregates, improving the mechanical properties and durability of the radiation-proof ultra-high performance concrete; in addition, it can effectively solve the problems of shortage of radiation-proof aggregates in the current market, insufficient radiation-proof effect of natural radiation-proof aggregates, and low crushing value; the preparation method of the present application uses mineral admixtures such as polycarboxylate water reducer and fly ash microspheres to optimize the workability of the concrete mixture, improve the compactness and homogeneity of the concrete, and further reduce the shrinkage of the concrete, improving the mechanical properties and volume stability of the lightweight ultra-high performance concrete; the present application combines the expansion agent to compensate for shrinkage and the internal curing effect of the pre-wetted radiation-proof functional aggregates to effectively improve the crack resistance and volume stability of the ultra-high performance concrete, and at the same time, can optimize the pore structure of the concrete and improve the durability of the concrete; the total content of Ba element and Pb element in the radiation-proof functional aggregates used in the present application accounts for more than 40% of the total element content of the aggregates, and the incorporation of the radiation-proof functional aggregates can effectively improve the γ-ray-proof performance of UHPC; the apparent density of the radiation-proof ultra-high performance concrete prepared by the present application is 2500~2800kg / m 3 , and at the same time, the compressive strength grade can reach above C100, and it has good workability, mechanical properties and volume stability, which can effectively improve the toughness, impact resistance, durability and γ-ray-proof performance of concrete components, and has important practical application value.

[0053] The following further illustrates the radiation-proof functional aggregates, γ-ray-proof ultra-high performance concrete and its preparation method of the present application with specific examples. This part further illustrates the content of the present invention with specific examples, but should not be construed as a limitation of the present invention. Unless otherwise specified, the technical means adopted in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0054] In the following examples and comparative examples, the cement used is Huaxin P·O52.5 ordinary Portland cement; the silica fume is provided by Sichuan Langtian Resources Comprehensive Utilization Company, with a SiO2 mass content of 95%, a specific surface area of 19000m 2 / kg, and a 28d activity index of 105%; the fly ash microspheres are provided by Tianjin Zhucheng New Materials Technology Co., Ltd., with a specific surface area of 1200m 2 / kg, the 28-day activity index > 90%, amorphous; the copper-plated steel fibers are produced by Wuhan Xintu Engineering New Materials Technology Co., Ltd., with a nominal length of 13 mm, an equivalent diameter of 0.20 mm, a fracture strength of about 3500 MPa, and an elastic modulus of about 52 GPa; the expansive agent is the HME-type expansive agent produced by Jiangsu Bote New Materials Co., Ltd., with a specific surface area of 3220 kg / m 3 , the 7-day restricted expansion rate in water is 0.062%; the water reducer is a polycarboxylate superplasticizer with a high water reduction rate and low air entrainment and a solid content of 50% produced by a certain new materials co., ltd. of Jiangsu Sobute; the water is ordinary tap water; the pore-forming agent includes a mixture of CaCO3 and MgCO3, where the mass ratio of CaCO3 to MgCO3 is 1:1.

[0055] The preparation method of the radiation-proof functional aggregate used in the following examples includes the following steps:

[0056] S1. Weigh each raw material according to the ratio. The components and their mass contents include: 30% lead powder, 15% cementitious material, and 55% barite powder; the mass ratio of portland cement to granulated blast furnace slag in the cementitious material is 70:30;

[0057] S2. Mix the weighed lead powder, cementitious material, and barite powder evenly, then put them into a pelletizing machine, and then add water to the pelletizing machine for granulation to obtain the first spherical embryo, controlling the particle size of the first spherical embryo to be 4.5 mm; among them, the mass of water is 8% of the sum of the masses of lead powder, cementitious material, and barite powder

[0058] S3. After curing the spherical embryo prepared in step S2, place it under autoclave curing conditions at a temperature of 210 °C and a pressure of 1 MPa for 8 h to form, that is, obtain the core layer;

[0059] S4. Mix γ-C2S and the pore-forming agent evenly (the mass of the pore-forming agent is 5% of the sum of the masses of γ-C2S and the pore-forming agent), and then add water and mix and stir to obtain a cementitious slurry; among them, the mass of water is 7% of the sum of the masses of γ-C2S and the pore-forming agent;

[0060] S5. Place the core layer in step S3 into the cementitious slurry formed in S4 for secondary granulation to obtain the second spherical blank, so that the surface of the core layer is covered with the shell layer cementitious slurry, and then place the second spherical blank in a carbonization device for carbonization for 2 h to obtain the radiation-proof functional aggregate.

[0061] Example 1

[0062] This application example also provides a γ-ray-proof ultra-high performance concrete, including the following raw materials: cement 767 kg / m 3 , fly ash microspheres 180 kg / m 3 , silica fume 180 kg / m 3, radiation - shielding functional aggregate 887 kg / m 3 , copper - plated steel fiber 200 kg / m 3 , water - reducing agent 30 kg / m 3 , expansive agent 72 kg / m 3 , water 204 kg / m 3 ;

[0063] The embodiment of the present application also provides a preparation method of γ - ray - shielding ultra - high - performance concrete, including the following steps:

[0064] S1. Put the radiation - shielding functional aggregate of 887 kg / m 3 into water and soak it until it reaches the saturated water state;

[0065] S2. Then put the soaked radiation - shielding functional aggregate, cement of 767 kg / m 3 , fly ash micro - beads of 180 kg / m 3 , silica fume of 180 kg / m 3 , expansive agent of 72 kg / m 3 into the concrete mixer for preliminary mixing for 3 min, then add water of 164 kg / m 3 and water - reducing agent of 30 kg / m 3 and mix again for 5 min, then add copper - plated steel fiber of 200 kg / m 3 and water of 40 kg / m 3 , continue to mix evenly, carry out mold - filling, vibration, and forming, then carry out film curing, then remove the mold, and finally carry out standard curing or steam curing to the specified age, thus obtaining the γ - ray - shielding ultra - high - performance concrete.

[0066] Example 2

[0067] The embodiment of the present application also provides a γ - ray - shielding ultra - high - performance concrete, including the following raw materials: cement 816 kg / m 3 , fly ash micro - beads 192 kg / m 3 , silica fume 192 kg / m 3 , radiation - shielding functional aggregate 887 kg / m 3 , copper - plated steel fiber 200 kg / m 3 , water - reducing agent 30 kg / m 3 , water 204 kg / m 3 ;

[0068] The embodiment of the present application also provides a preparation method of γ - ray - shielding ultra - high - performance concrete, including the following steps:

[0069] S1. Put the radiation - shielding functional aggregate of 887 kg / m 3 into water and soak it until it reaches the saturated water state;

[0070] S2. Then, the radiation-proof functional aggregate after soaking, 816 kg / m 3 of cement, 192 kg / m 3 of fly ash microspheres, 192 kg / m 3 of silica fume are added to a concrete mixer and premixed for 3 min, then 164 kg / m 3 of water and 30 kg / m 3 of water reducing agent are added and stirred again for 5 min. Then, 200 kg / m 3 of copper-plated steel fibers, 40 kg / m 3 of water are added and stirred evenly. After molding, vibrating, and forming, film curing is carried out, then the formwork is removed, and finally standard curing or steam curing is carried out until the specified age, and the anti-γ-ray ultra-high performance concrete is obtained.

[0071] Example 3

[0072] This application example also provides an anti-γ-ray ultra-high performance concrete, including the following raw materials: 800 kg / m 3 of cement, 150 kg / m 3 of fly ash microspheres, 180 kg / m 3 of silica fume, 948 kg / m 3 of radiation-proof functional aggregate, 200 kg / m 3 of copper-plated steel fibers, 28.25 kg / m 3 of water reducing agent, 192 kg / m 3 of water;

[0073] This application example also provides a preparation method of anti-γ-ray ultra-high performance concrete, including the following steps:

[0074] S1. Put 948 kg / m 3 of radiation-proof functional aggregate into water and soak it until it reaches the saturated water state;

[0075] S2. Then, the radiation-proof functional aggregate after soaking, 800 kg / m 3 of cement, 150 kg / m 3 of fly ash microspheres, 180 kg / m 3 of silica fume are added to a concrete mixer and premixed for 3 min, then 154 kg / m 3 of water and 28.25 kg / m 3 of water reducing agent are added and stirred again for 5 min. Then, 200 kg / m 3 of copper-plated steel fibers, 38 kg / m 3 of water are added and stirred evenly. After molding, vibrating, and forming, film curing is carried out, then the formwork is removed, and finally standard curing or steam curing is carried out until the specified age, and the anti-γ-ray ultra-high performance concrete is obtained.

[0076] Comparative Example 1

[0077] This comparative example also provides a kind of anti-γ-ray ultra-high performance concrete, including the following raw materials: 816 kg / m of cement 3 , 192 kg / m of fly ash microspheres 3 , 192 kg / m of silica fume 3 , 200 kg / m of copper-coated steel fibers 3 , 869 kg / m of quartz sand 3 , 30 kg / m of water reducer 3 , 204 kg / m of water 3 ;

[0078] This comparative example also provides a preparation method of the anti-γ-ray ultra-high performance concrete, including the following steps:

[0079] S1. Add 869 kg / m 3 of quartz sand, 816 kg / m 3 of cement, 192 kg / m 3 of fly ash microspheres, 192 kg / m 3 of silica fume into a concrete mixer for pre-mixing for 3 min, then add 164 kg / m 3 of water and 30 kg / m 3 of water reducer and stir again for 5 min, then add 200 kg / m 3 of copper-coated steel fibers, 40 kg / m 3 of water and continue to stir evenly. After molding, vibrating and forming, carry out film curing, then remove the mold, and finally carry out standard curing or steam curing to the specified age to obtain the anti-γ-ray ultra-high performance concrete.

[0080] Performance test

[0081] Test the performance of the anti-γ-ray ultra-high performance concrete prepared in Test Examples 1 to 3 and Comparative Example 1. The results are shown in Table 1.

[0082] Table 1 - Performance of the anti-γ-ray ultra-high performance concrete in Test Examples 1 to 3 and Comparative Example 1

[0083] Example Slump (mm) Spread (mm) <![CDATA[Apparent density (kg / m 3 )]]> 28-day compressive strength (MPa) Flexural tensile strength (MPa) Impermeability grade 180-day shrinkage rate (με) Example 1 250 610 2550 123.8 23.2 P27 365 Example 2 265 660 2560 130.1 25.5 P28 675 Example 3 235 585 2510 121.9 20.4 P26 630 Comparative example 1 270 675 2530 141.6 22.9 P27 850

[0084] Test the shielding effect of the anti-γ-ray ultra-high performance concrete prepared in Test Examples 1 to 3 and Comparative Example 1 on the γ-ray of Co60 source. The results are shown in Table 2.

[0085] Table 2 - Shielding effect of the anti-γ-ray ultra-high performance concrete in different examples on the γ-ray of Co60 source

[0086] Example <![CDATA[μ fitting result (cm -1 )]]> Half-value layer thickness HVT (cm) Tenth-value layer thickness TVT (cm) Example 1 0.11501 6.03 20.02 Example 2 0.11349 6.11 20.29 Example 3 0.11640 5.95 19.78 Comparative example 1 0.09624 7.20 23.93

[0087] As can be seen from Tables 1 to 2, the anti-γ-ray ultra-high performance concrete obtained by the present invention has good workability, mechanical properties and γ-ray shielding properties. The apparent density of the obtained radiation-proof ultra-high performance concrete is above 2500 kg / m 3 Above, the self-weight is increased by more than 14% compared with general lightweight aggregate ultra-high performance concrete, the compressive strength grade can reach above C120, and it has high toughness and good workability (slump / spread), crack resistance and impermeability grade.

[0088] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A radiation-proof functional aggregate, characterized in that, The radiation protection functional aggregate includes a core layer and a shell layer coated outside the core layer. Among them, the core layer includes the following raw materials: lead powder, barite powder, and a cementitious material. The cementitious material includes Portland cement and granulated blast furnace slag. The mass ratio of the lead powder, barite powder, and cementitious material is (10 - 50):(30 - 70):(10 - 25); the shell layer is γ-C2S after carbonization.

2. A radiation-proof functional aggregate as described in claim 1, characterized in that, The diameter of the core layer is 3 - 8 mm, and the diameter of the radiation protection functional aggregate is 5 - 10 mm.

3. A preparation method of the radiation-proof functional aggregate according to any one of claims 1 to 2, characterized in that, It includes the following steps: Mix lead powder, barite powder, and cementitious material and stir, then add water and granulate to obtain a first green body. Cure the first green body and then place it under autoclave curing conditions at a temperature of 200 - 220 °C and a pressure of 0.5 - 2 MPa for 6 - 8 h to form the core layer. Mix γ-C2S, water, and a pore-forming agent and stir to obtain a cementitious slurry. Place the core layer in the cementitious slurry formed in the previous step for secondary granulation to obtain a second green body, so that the surface of the core layer is covered with the shell layer cementitious slurry. Then place the second green body in a carbonization device for carbonization for 1 - 3 h to obtain the radiation protection functional aggregate.

4. A γ-ray resistant ultra-high performance concrete, characterized in that, It includes the following raw materials: 700 - 900 kg / m of cement 3 , 150 - 250 kg / m of fly ash microspheres 3 , 150 - 250 kg / m of silica fume 3 , 500 - 1500 kg / m of radiation-proof functional aggregate 3 , 100 - 250 kg / m of copper-plated steel fibers 3 , 20 - 35 kg / m of water reducer 3 , 60 - 85 kg / m of expansive agent 3 , 170 - 220 kg / m of water 3 ; Among them, the radiation protection functional aggregate is the radiation protection functional aggregate described in any one of claims 1 - 2.

5. The anti-γ-ray ultra-high performance concrete according to claim 4, wherein The cement is P·O52.5 or P·II 52.5 Portland cement.

6. The ultra-high performance concrete for preventing γ-rays according to claim 4, wherein, The loss on ignition of the fly ash microspheres is ≤5.0%, the water demand ratio is ≤90%, and the volume ratio of spherical particles is ≥95%.

7. The ultra-high performance concrete for preventing γ-rays according to claim 4, characterized in that, The SiO2 mass content in the silica fume is ≥ 95%, the specific surface area is ≥ 15500 m 2 / kg, and the 28-day activity index is ≥ 100%.

8. The anti-γ-ray ultra-high performance concrete according to claim 4, characterized in that, The fracture strength of the copper-plated steel fiber is ≥3000 MPa, and the elastic modulus is 40 - 60 GPa.

9. The anti-γ-ray ultra-high performance concrete according to claim 4, characterized in that, The water reducer is a polycarboxylate water reducer.

10. A preparation method of the ultra-high performance concrete for preventing γ-rays as described in any one of claims 4 to 9, characterized in that, It includes the following steps: Soak the radiation protection functional aggregate in water until it reaches a saturated state. Then mix and stir the soaked radiation protection functional aggregate, cement, silica fume, fly ash microspheres, and expansive agent. Then add water and a water reducer and stir again. Finally, add copper-plated steel fibers and continue to stir evenly. After molding, vibrating, and forming, perform film curing, then remove the mold, and finally perform standard curing or steam curing to obtain γ-ray resistant ultra-high performance concrete.