Radiation-proof boron-containing cement for nuclear power and preparation method thereof

Abstract

The application belongs to the technical field of building materials, and specifically discloses a kind of nuclear power use radiation-proof boron-containing cement and its preparation method.Nuclear power use radiation-proof boron-containing cement, by weight parts, includes the following raw materials:portland cement 325-342 parts, boron nitride 115-128 parts, fine river sand 650-662 parts, water 226-238 parts.The nuclear power use radiation-proof boron-containing cement prepared in the application has good strength and tensile strength, and a certain amount of portland cement, boron nitride, fine river sand is set, and the components can significantly improve the compressive strength and durability of the nuclear power use radiation-proof boron-containing cement.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of building materials, in particular to a boron-containing radiation-proof cement for nuclear power and a preparation method thereof. BACKGROUND

[0002] The boron-containing radiation-proof cement for nuclear power is a special building material, which is formed by grinding high-alumina cement clinker, forged boracite and natural anhydrite together, and is widely applied to radiation places such as nuclear power plants, radioactive medical equipment rooms and biochemical laboratories due to its excellent radiation-proof performance.

[0003] With the development of nuclear power plant construction and the increasing demand for radioactive waste treatment, the demand for radiation-proof materials is also increasing. Boron is widely used in radiation-proof materials due to its good absorption performance for neutrons. The BO3 ion in boron has a large cross section for neutrons. When neutrons pass through the boron element, they are absorbed and excited to emit alpha, Li, Be and other ions and gamma rays, thereby slowing down the speed and energy of radiation and reducing the radiation dose.

[0004] In the existing boron-containing radiation-proof cement for nuclear power, the boron element reacts with the calcium ion in the cement during the hardening process to form a dense calcium borate hydrate film covering the surface of the cement particles, preventing the cement particles from contacting the external solution, and causing the cement hydration reaction to fail to proceed normally, thereby affecting the strength development of the cement. SUMMARY

[0005] In order to improve the problem of poor strength of the boron-containing radiation-proof cement for nuclear power, the application provides a boron-containing radiation-proof cement for nuclear power and a preparation method thereof.

[0006] The application provides a boron-containing radiation-proof cement for nuclear power, which adopts the following technical scheme:

[0007] The boron-containing radiation-proof cement for nuclear power comprises the following raw materials in parts by weight: 325-342 parts of Portland cement, 115-128 parts of boron nitride, 650-662 parts of fine river sand and 226-238 parts of water.

[0008] By adopting the above technical scheme, the Portland cement is the main component of the cement, which provides the basic strength and hardening performance of the mixture. The amount of Portland cement is limited to ensure that the cement mixture has sufficient structural strength. Boron nitride has good thermal stability and chemical stability, and also has strong neutron absorption capacity, which improves the radiation-proof performance of the cement. The fine river sand has a small particle size and a large surface area, which can fully fill the gaps between the cement particles and improve the compactness and cohesion of the cement.

[0009] The hydration calcium borate film formed by the reaction of boron element and calcium ion in cement has a complex influence on the strength development of cement, and fine river sand can promote the cement hydration reaction and improve the strength of cement. After mixing with cement, fine river sand can provide a better reaction interface to promote the hydration reaction of cement. The cement hydration produces cementitious material which can better fill the gap between fine river sand particles, forming a more compact structure.

[0010] The fine river sand and the cement hydration product together constitute the skeleton structure of the cement, which directly contributes to the strength of the cement. By setting a certain amount of Portland cement, boron nitride and fine river sand, the compressive strength and durability of the anti-radiation boron-containing cement for nuclear power can be significantly improved.

[0011] Preferably, the Portland cement is 333 parts, the boron nitride is 122 parts, the fine river sand is 656 parts, and the water is 231 parts by weight.

[0012] By adopting the above technical solution, the amount of Portland cement, boron nitride and fine river sand is further limited. In the anti-radiation boron-containing cement for nuclear power, Portland cement as a basic cementitious material can form a dense structure with other ingredients. Boron nitride has excellent anti-neutron radiation performance due to its wide band gap and high thermal conductivity. The addition of boron nitride in the anti-radiation boron-containing cement for nuclear power can significantly improve the anti-neutron radiation ability of the cement. Fine river sand can fill the gap between Portland cement particles, improve the density and cohesion of the cement, and the hydration calcium borate film formed by the reaction of boron element and calcium ion in cement affects the strength of the cement. Fine river sand and Portland cement hydration product together constitute the skeleton structure of the cement, promote the hydration reaction of cement and improve the strength of cement system. The combination of each component in the anti-radiation boron-containing cement for nuclear power further improves the compressive strength and durability of the cement.

[0013] Preferably, it also includes 50-60 parts of modified fly ash, 20-30 parts of gypsum and 40-45 parts of modified attapulgite.

[0014] By adopting the above technical solution, the modified fly ash can fill the gap in the cementitious system, increase the density of the cement, and thus improve its strength. At the same time, the silicate and aluminate in the fly ash will react with other ingredients in the cement to generate new cementitious material, further enhancing the mechanical properties and durability of the cement. Gypsum adjusts the setting time of cement to avoid rapid setting of cement, and cooperates with modified fly ash to improve the mechanical strength of cement. Modified attapulgite has porosity and good adsorbability, which can increase the internal space of cement, reduce the porosity, increase the hardness of cement and make the quality more stable and durable. Moreover, the porous structure and strong adsorbability of attapulgite can adsorb and fix radioactive substances, reducing their radiation impact on the surrounding environment.

[0015] Preferably, the method for preparing the modified fly ash comprises the following steps:

[0016] (1) dispersing fly ash in a salicylic acid solution, stirring for 20-25 minutes, washing with water, and then dispersing in a potassium hydroxide solution, stirring for 35-40 minutes, washing with water, and calcining at 340-350° C. for 30-35 minutes to obtain pretreated fly ash;

[0017] (2) dispersing the modified blast furnace slag in deionized water, adding the pretreated fly ash, polyvinyl alcohol and silane coupling agent of step (1), stirring at a temperature of 60-65° C. for 2-3 hours, and filtering to obtain a mixture;

[0018] (3) spraying nano glue on the surface of the mixture in step (2), drying, and grinding to obtain modified fly ash;

[0019] Disperse nano-silica in deionized water, add polyvinyl alcohol and sodium lauryl sulfate, and stir evenly to obtain nano-glue.

[0020] By adopting the above technical solution, the fly ash surface is treated with salicylic acid to improve the wettability and dispersibility of the fly ash surface, and then the fly ash surface is further treated with potassium hydroxide solution to remove other impurities in the fly ash. The obtained pretreated fly ash has good structural stability and dispersibility, which is conducive to subsequent mixing with other components.

[0021] Both modified blast furnace slag and fly ash are highly active. The modified blast furnace slag can be loaded onto the surface and pores of fly ash particles, increasing the fly ash's strength and stability. The active components in the blast furnace slag and fly ash subsequently react chemically with the hydration products in the cement clinker to form new compounds with high strength, thereby enhancing the strength of the cement. Polyvinyl alcohol, with its excellent solubility and stability, acts as a binder, ensuring a tight bond between the modified blast furnace slag and fly ash, increasing the performance stability of the modified fly ash and imparting superior strength to the modified fly ash. The silane coupling agent acts as a bridge, connecting the blast furnace slag, fly ash, and polyvinyl alcohol, strengthening the interfacial bonding between them and contributing to the overall strength and durability of the material.

[0022] Spray the nanometer glue evenly on the surface of the mixture obtained in step (2), the nanometer glue is composed of nanometer silicon dioxide, polyvinyl alcohol, glutaraldehyde and sodium dodecyl sulfonate, which is used to enhance the adhesion and stability of the mixture, further make the modified blast furnace slag and fly ash adhere closely, increase the performance stability of the modified fly ash, and subsequently improve the mechanical strength and durability of the cement. In the nanometer glue, the nanometer silicon dioxide provides excellent mechanical properties and stability, the polyvinyl alcohol increases the viscosity of the nanometer glue, making it more adhesive, and the sodium dodecyl sulfonate can reduce the surface energy of the nanometer silicon dioxide particles through electrostatic adsorption and solvation, making them uniformly dispersed in the mixed system of anhydrous ethanol and polyvinyl alcohol. The obtained nanometer glue has good viscosity and mechanical strength, which helps to make other components adhere closely and improve the comprehensive performance of the modified fly ash.

[0023] Preferably, the mass ratio of the fly ash, the modified blast furnace slag and the nanometer glue is 1:0.6-0.7:0.2-0.3.

[0024] By adopting the above technical solution, the mass ratio of the fly ash, the modified blast furnace slag and the nanometer glue is further limited within a certain range, the modified fly ash obtained has relatively optimal comprehensive performance, the structure of the modified blast furnace slag is compact and mechanically strong, and can be loaded on the surface and pores of the fly ash, improving the structural strength of the fly ash, the nanometer glue has relatively optimal adhesion and film-forming property, and can coat the fly ash, making the fly ash and the modified blast furnace slag adhere closely, increasing the mechanical properties and durability of the modified fly ash, and subsequently improving the compressive strength, flexural strength and impermeability of the cement, further optimizing the anti-radiation performance of the anti-radiation boron-containing cement for nuclear power, and making it have better shielding effect on X-ray, γ-ray, fast neutron and thermal neutron radiation.

[0025] Preferably, the preparation method of the modified blast furnace slag comprises the following steps: washing the blast furnace slag to remove impurities, then dispersing it in a sulfuric acid solution, ultrasonic dispersion for 3-4 h, filtration, water washing, dispersing it in a sodium hydroxide solution again, ultrasonic dispersion for 1-2 h, and water washing to obtain pretreated blast furnace slag; dispersing the pretreated blast furnace slag in deionized water, adding glass fiber, hydroxypropyl methyl cellulose and sodium gluconate, stirring for 4-6 h, and drying to obtain the modified blast furnace slag.

[0026] By adopting the above technical solution, the sulfuric acid reacts with some components in the blast furnace slag to remove impurities, change the surface properties of the blast furnace slag, and the sodium hydroxide solution further processes the blast furnace slag to improve the pH value and surface properties of the blast furnace slag, and increase the specific surface area of the blast furnace slag, so that the blast furnace slag is helpful for mixing with subsequent components.

[0027] The pretreated blast furnace slag is dispersed in deionized water, and glass fibers, hydroxypropyl methyl cellulose and sodium gluconate are added. The glass fibers have good strength and toughness, can be adsorbed on the surface and pores of the blast furnace slag, and increase the strength and toughness of the blast furnace slag. The hydroxypropyl methyl cellulose has excellent bonding performance, can improve the bonding force between the blast furnace slag particles, make the blast furnace slag particles and the glass fibers better bond, and increase the structural strength and mechanical properties of the blast furnace slag particles. The sodium gluconate has good dispersing performance, is helpful to the dispersion of the blast furnace slag particles and the glass fibers in the deionized water, and avoids the agglomeration between the particles. The obtained modified blast furnace slag has excellent physical and chemical properties, such as high strength, high toughness, good bonding and dispersing properties, and is subsequently applied in fly ash to improve the corresponding performance of the fly ash.

[0028] Preferably, the preparation method of the modified attapulgite comprises the following steps:

[0029] (1) dispersing attapulgite in a hydrochloric acid solution, washing with water, calcining at 300-320℃ for 2-3h, then dispersing in deionized water, adding betaine, filtering and drying to obtain treated attapulgite;

[0030] (2) dispersing modified wood chips in deionized water, adding the treated attapulgite of step (1), stirring at a temperature of 65-70℃ for 1-2h, adding sodium alginate and barium sulfate, continuing to stir for 1-2h, and drying to obtain modified attapulgite.

[0031] By using the above technical scheme, the attapulgite is dispersed in a hydrochloric acid solution, the hydrochloric acid can react with impurities or some components on the surface of the attapulgite, thereby removing these impurities or changing the surface properties of the attapulgite; calcining at 300-320℃ further removes volatile components and organic matter in the attapulgite, and improves its thermal stability and mechanical strength.

[0032] The betaine improves the dispersibility of the attapulgite in water, and reacts with the hydroxyl and carboxyl functional groups on the surface of the attapulgite, changes the surface properties and functional group types of the attapulgite, improves the dispersibility of the attapulgite in water, thereby improving its dispersion stability, and is helpful for subsequent mixing with other components.

[0033] The modified wood chips have a porous structure and good heat insulation performance, can be adsorbed on the surface of the attapulgite, and increase the flowability, strength and heat insulation performance of the attapulgite. The sodium alginate has good bonding and film-forming properties, makes the attapulgite and the modified wood chips bond closely, and makes the modified attapulgite have excellent comprehensive performance. The barium sulfate can be filled in the pores of the modified wood chips and the attapulgite, increase the density and hardness of the modified attapulgite, and improve the radiation resistance of the subsequent cement.

[0034] Preferably, the mass ratio of the attapulgite, modified sawdust and sodium alginate is 1:0.4-0.5:0.15-0.25.

[0035] By adopting the technical scheme, the mass ratio of the attapulgite, modified sawdust and sodium alginate is limited in a certain range, the attapulgite obtained has excellent mechanical strength and durability, the attapulgite has excellent adsorption performance and ion exchange capacity, a hydration reaction occurs with cement to generate new hydration products to fill pores and improve the density and strength of the material. The modified sawdust has a porous structure and can be adsorbed on the surface of the attapulgite to increase the heat insulation performance of the attapulgite. The sodium alginate has good stability and viscosity to promote the adhesion of the attapulgite and the modified sawdust. In the radiation-proof boron-containing cement for nuclear power, the sodium alginate can play multiple roles of enhancing the radiation-proof performance, improving the material strength, improving the heat insulation performance, enhancing the material stability, improving the impermeability and promoting the solidification of radioactive substances.

[0036] Preferably, the preparation method of the modified sawdust comprises the following steps: grinding the sawdust, dispersing the sawdust in ammonia water, stirring for 10-15 min, washing with water, then dispersing the sawdust in deionized water, adding silicon carbide whiskers, starch and sodium hexametaphosphate, stirring at 70-75℃ for 2-3 h, and drying to obtain the modified sawdust.

[0037] By adopting the technical scheme, the surface of the sawdust is activated by ammonia water to improve the dispersibility and stability of the sawdust. The sawdust is then dispersed in deionized water, and silicon carbide whiskers, starch and sodium hexametaphosphate are added. The silicon carbide whiskers have high strength and high elastic modulus, and can be loaded in the structure and pores of the sawdust to increase the mechanical properties and wear resistance of the sawdust. The starch has good dispersibility, hygroscopicity and adhesion, which helps the adhesion between the sawdust and the silicon carbide whiskers and increases the performance stability of the sawdust. The sodium hexametaphosphate helps to maintain the dispersibility of the sawdust particles, so that the silicon carbide whiskers can be uniformly loaded on the surface of the sawdust. The modified sawdust has excellent dispersibility, mechanical properties and wear resistance, which further helps to improve the corresponding performance of the modified attapulgite.

[0038] In a second aspect, the application also provides a preparation method of the radiation-proof boron-containing cement for nuclear power, which comprises the following steps: mixing silicate cement, boron nitride, fine river sand and water, stirring uniformly, and grinding to a sieve residue of not more than 10% through a 40μm square hole sieve to obtain the radiation-proof boron-containing cement for nuclear power.

[0039] By adopting the technical scheme, the preparation method is simple and short in process time, which helps to improve the production efficiency of the preparation of the radiation-proof boron-containing cement for nuclear power, and the obtained radiation-proof boron-containing cement for nuclear power has good mechanical properties.

[0040] In summary, the application has the following beneficial effects:

[0041] 1、The hydrated calcium borate film formed by the reaction of boron elements in the application with calcium ions in cement has a complex influence on the strength development of cement, while fine river sand helps to promote the cement hydration reaction and increase the strength of cement. After mixing with cement, fine river sand can provide a better reaction interface, promote the hydration reaction of cement, and improve the compactness and cohesion of cement.

[0042] 2、The modified fly ash in the application can fill the voids in the cementitious system, increase the density of cement, and thus improve its strength; at the same time, the silicates and aluminates in fly ash will react with other components in cement to generate new cementitious materials, further enhancing the mechanical properties and durability of cement.

[0043] 3、The modified attapulgite in the application has porosity and good adsorbability, which can increase the internal space of cement, reduce the porosity, increase the hardness of cement, and make the quality more stable and durable; moreover, the porous structure and strong adsorbability of attapulgite can adsorb and fix radioactive substances, reducing their radiation impact on the surrounding environment. DETAILED DESCRIPTION

[0044] The application will be further described in detail below in conjunction with examples.

[0045] The raw materials used in the examples and comparative examples can be obtained by market purchase.

[0046] Preparation example of modified fly ash

[0047] Preparation example 1-1

[0048] The preparation method of modified fly ash includes the following steps:

[0049] (1) Disperse 80 kg of fly ash into 100 L of a 8% mass fraction salicylic acid solution, stir for 25 min, wash with water, then disperse into 110 L of a 12% mass fraction potassium hydroxide solution, stir for 38 min, wash with water, and calcine at 345 ℃ for 35 min to obtain pretreated fly ash;

[0050] (2) Disperse the modified blast furnace slag in 90 L of deionized water, add the pretreated fly ash of step (1), 7 kg of polyvinyl alcohol and 3 kg of silane coupling agent KH-550, stir at a temperature of 65 ℃ for 3 h, filter, and obtain a mixture;

[0051] (3) Spray nano glue on the surface of the mixture of step (2), dry, grind, and obtain modified fly ash;

[0052] 8kg nano-silica was dispersed in 30L deionized water, 6kg polyvinyl alcohol, 3kg sodium dodecyl sulfate were added and stirred uniformly to obtain nano-glue, which was used to prepare modified fly ash.

[0053] The mass ratio of fly ash, modified blast furnace slag and nano-glue was 1:0.6:0.3.

[0054] The preparation method of modified blast furnace slag comprises the following steps: 70kg blast furnace slag was washed by water to remove impurities, then dispersed in 100L 5% sulfuric acid solution, ultrasonic dispersion for 4h, filtration, water washing, then dispersed in 100L 10% sodium hydroxide solution, ultrasonic dispersion for 2h, water washing, to obtain pretreated blast furnace slag; the pretreated blast furnace slag was dispersed in 150L deionized water, 18kg glass fiber, 14kg hydroxypropyl methyl cellulose and 6kg sodium gluconate were added, stirred for 6h, dried to obtain modified blast furnace slag.

[0055] Preparation Example 1-2

[0056] The difference from Preparation Example 1-1 is that in step (2), no modified blast furnace slag is added.

[0057] Preparation Example 1-3

[0058] The difference from Preparation Example 1-1 is that in step (3), no nano-glue is added.

[0059] Preparation Example 1-4

[0060] The difference from Preparation Example 1-1 is that the mass ratio of fly ash, modified blast furnace slag and nano-glue is 1:0.7:0.2.

[0061] Preparation Example 1-5

[0062] The difference from Preparation Example 1-1 is that the mass ratio of fly ash, modified blast furnace slag and nano-glue is 1:0.1:0.6.

[0063] Preparation Example 1-6

[0064] The difference from Preparation Example 1-1 is that in the preparation method of modified blast furnace slag, no glass fiber is added.

[0065] Preparation Example 1-7

[0066] The difference from Preparation Example 1-1 is that in the preparation method of modified blast furnace slag, no hydroxypropyl methyl cellulose is added.

[0067] Preparation Example of modified attapulgite

[0068] Preparation Example 2-1

[0069] A method for preparing modified palygorskite includes the following steps:

[0070] (1) 60 kg of palygorskite is dispersed in 85 L of 5% hydrochloric acid solution, washed with water, calcined at 320°C for 3 h, then dispersed in 90 L of deionized water, 5 kg of betaine is added, filtered and dried to obtain treated palygorskite;

[0071] (2) The modified sawdust is dispersed in 180 L of deionized water, the treated palygorskite of step (1) is added, stirred at 70°C for 2 h, sodium alginate and 4 kg of barium sulfate are added, and stirring is continued for 2 h, and then dried to obtain modified palygorskite.

[0072] The mass ratio of palygorskite, modified sawdust and sodium alginate is 1:0.4:0.15.

[0073] A method for preparing modified sawdust includes the following steps: 45 kg of sawdust is ground, dispersed in 60 L of 18% ammonia water, stirred for 15 min, washed with water, then dispersed in 67 L of deionized water, 12 kg of silicon carbide whiskers, 9 kg of starch and 3 kg of sodium hexametaphosphate are added, stirred at 75°C for 3 h, and dried to obtain modified sawdust.

[0074] Preparation Example 2-2

[0075] The difference from Preparation Example 2-1 is that in step (2), no modified sawdust is added.

[0076] Preparation Example 2-3

[0077] The difference from Preparation Example 2-1 is that in step (2), no sodium alginate is added.

[0078] Preparation Example 2-4

[0079] The difference from Preparation Example 2-1 is that the mass ratio of palygorskite, modified sawdust and sodium alginate is 1:0.5:0.25.

[0080] Preparation Example 2-5

[0081] The difference from Preparation Example 2-1 is that the mass ratio of palygorskite, modified sawdust and sodium alginate is 1:0.1:0.6.

[0082] Preparation Example 2-6

[0083] The difference from Preparation Example 2-1 is that in the preparation method of modified sawdust, no silicon carbide whiskers are added.

[0084] Preparation Example 2-7

[0085] The difference from Preparation Example 2-1 is that in the preparation method of modified sawdust, no starch is added.

[0086] Embodiment

[0087] Embodiment 1

[0088] A kind of anti-radiation boron-containing cement for nuclear power, including the following raw materials by weight: Portland cement 333 kg, boron nitride 122 kg, fine river sand 656 kg, water 231 kg;

[0089] Wherein, Portland cement adopts Portland cement with code P·I, and its quality meets the provisions of GB175-2017.

[0090] Fine river sand adopts fine river sand screened, fineness modulus μf is 1.9, dryness ≤1%, and its quality meets the provisions of JGJ52-2006.

[0091] Boron nitride with purity BN≥98% is used, which meets standard 1108AT0041.

[0092] Tap water with chloride ion content less than 30 mg / L and quality meeting the provisions of JGJ63-2006 is used.

[0093] The preparation method of the above anti-radiation boron-containing cement for nuclear power includes the following steps: mixing Portland cement, boron nitride, fine river sand and water, stirring uniformly, and grinding to a sieve residue of 8% through a 40 μm square hole sieve to obtain the anti-radiation boron-containing cement for nuclear power.

[0094] Embodiment 2

[0095] An anti-radiation boron-containing cement for nuclear power, which differs from embodiment 1 in that it includes the following raw materials by weight: Portland cement 325 kg, boron nitride 115 kg, fine river sand 650 kg, and water 226 kg.

[0096] Embodiment 3

[0097] An anti-radiation boron-containing cement for nuclear power, which differs from embodiment 1 in that it includes the following raw materials: Portland cement 342 kg, boron nitride 128 kg, fine river sand 662 kg, and water 238 kg.

[0098] Embodiment 4

[0099] An anti-radiation boron-containing cement for nuclear power, which differs from embodiment 1 in that it further includes modified fly ash 50 kg, gypsum 20 kg, and modified attapulgite 40 kg.

[0100] The modified fly ash is prepared according to Preparation Example 1-1, and the modified attapulgite is prepared according to Preparation Example 2-1.

[0101] Embodiment 5

[0102] A radiation-proof boron-containing cement for nuclear power, which is different from Example 1 in that it further comprises modified fly ash 60 kg, gypsum 30 kg, and modified attapulgite 45 kg.

[0103] Example 6

[0104] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified fly ash is prepared by Preparation Example 1-2.

[0105] Example 7

[0106] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified fly ash is prepared by Preparation Example 1-3.

[0107] Example 8

[0108] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified fly ash is prepared by Preparation Example 1-4.

[0109] Example 9

[0110] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified fly ash is prepared by Preparation Example 1-5.

[0111] Example 10

[0112] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified fly ash is prepared by Preparation Example 1-6.

[0113] Example 11

[0114] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified fly ash is prepared by Preparation Example 1-7.

[0115] Example 12

[0116] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified attapulgite is prepared by Preparation Example 2-2.

[0117] Example 13

[0118] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified attapulgite is prepared by Preparation Example 2-3.

[0119] Example 14

[0120] A radiation-proof boron-containing cement for nuclear power, which is different from Example 4 in that the modified attapulgite is prepared by Preparation Example 2-4.

[0121] Example 15

[0122] A kind of nuclear power anti-radiation boron-containing cement, the difference with example 4 is that the modified palygorskite is prepared by preparation example 2-5.

[0123] Example 16

[0124] A kind of nuclear power anti-radiation boron-containing cement, the difference with example 4 is that the modified palygorskite is prepared by preparation example 2-6.

[0125] Example 17

[0126] A kind of nuclear power anti-radiation boron-containing cement, the difference with example 4 is that the modified palygorskite is prepared by preparation example 2-7.

[0127] Comparative example

[0128] Comparative example 1

[0129] A kind of nuclear power anti-radiation boron-containing cement, the difference with example 1 is that no fine river sand is added.

[0130] Performance test test

[0131] The anti-radiation boron-containing cement prepared by example 1-17 and comparative example 1 is tested for performance;

[0132] The anti-radiation cement is mixed with a certain amount of water (water-cement ratio is 0.3) to form neat paste, poured into a hollow spherical mold shell with a thickness of 40mm, the mold is placed in a curing room for 24h, demolding, then the sample is placed in a water tank at 20℃, curing for 28d, to obtain anti-radiation cement sample.

[0133] The compressive strength and flexural strength are tested by standard "GB / T17671-1999 Cement Mortar Strength Test" method;The bonding strength is tested by standard "JGJ 110-2008 Building Engineering Facing Brick Bonding Strength Test Standard"

[0134] The impact resistance test is carried out by pendulum method, using XJJ-50 simply supported beam impact testing machine, and the test results are shown in table 1.

[0135] Table 1 test data of example and comparative example

[0136]

[0137]

[0138] As can be seen from Table 1, the anti-radiation boron-containing cement for nuclear power prepared in Examples 1-3 has good mechanical properties, mechanical strength and anti-radiation performance. The 3d compressive strength of Example 1 is 27.3 MPa, the 28d compressive strength is 48.9 MPa, the 3d flexural tensile strength is 5.1 MPa, the 28d flexural tensile strength is 8.0 MPa, the bonding strength is 1.42 MPa, and the impact energy is 1296 J / m 2 The anti-radiation performance is detected by a low-background multi-channel gamma spectrometer. The radiation shielding rate of Example 1 is 85.9%. As can be seen from Table 1, the 3d compressive strength, 28d compressive strength, 3d flexural tensile strength, 28d flexural tensile strength, bonding strength and impact energy of Comparative Example 1 are obviously worse than those of Examples 1-3, which shows that the anti-radiation boron-containing cement for nuclear power has good mechanical properties and mechanical strength. The fine river sand and the cement hydration product together form the skeleton structure of the cement, which improves the strength of the cement. The use of silicate cement, boron nitride, fine river sand and fine river sand in a certain amount can significantly improve the compressive strength and durability of the anti-radiation boron-containing cement for nuclear power.

[0139] As can be seen from Table 1, the 3d compressive strength of Example 4 is 39.8 MPa, the 28d compressive strength is 62.8 MPa, the 3d flexural tensile strength is 8.3 MPa, the 28d flexural tensile strength is 11.6 MPa, the bonding strength is 2.35 MPa, and the impact energy is 1534 J / m 2 The modified fly ash can fill the voids in the cement gel system, increase the density of the cement, and thus improve its strength. The gypsum adjusts the setting time of the cement to avoid rapid setting of the cement. The modified fly ash and the gypsum together improve the mechanical strength of the cement. The modified attapulgite has porosity and good adsorbability, which can increase the internal space of the cement, reduce the porosity, increase the hardness of the cement, and make the quality of the cement more stable and durable.

[0140] The preparation methods of the modified fly ash in Examples 6-7 do not add modified blast furnace slag and nano glue respectively, and the mass ratios of the fly ash, the modified blast furnace slag and the nano glue are changed in Examples 8-9. As can be seen from Table 1, the test effects of the 3d compressive strength, the 28d compressive strength, the 3d flexural tensile strength, the 28d flexural tensile strength, the bonding strength and the impact work resistance of Examples 6-7 are obviously poorer than those of Examples 4-5 and Example 8, and the test effects of the corresponding properties of Example 9 are better than those of Examples 6-7 but poorer than those of Examples 4-5 and Example 8, indicating that the modified blast furnace slag has a compact structure and a strong mechanical structure, can be loaded on the surface and in the pores of the fly ash, improves the structural strength of the fly ash, the nano glue has good adhesion and film-forming properties, can coat the fly ash, makes the fly ash and the modified blast furnace slag adhere closely, and increases the mechanical properties and the durability of the modified fly ash, thereby subsequently improving the compressive strength, the flexural strength and the impermeability of the cement.

[0141] The preparation methods of the modified blast furnace slag in Examples 10-11 do not add glass fiber and hydroxypropyl methyl cellulose respectively. As can be seen from Table 1, the test effects of the 3d compressive strength, the 28d compressive strength, the 3d flexural tensile strength, the 28d flexural tensile strength, the bonding strength and the impact work resistance of Examples 10-11 are obviously poorer than those of Examples 4-5 but better than those of Example 6, indicating that the glass fiber has good strength and toughness, can be adsorbed on the surface and in the pores of the blast furnace slag, increases the strength and toughness of the blast furnace slag, and the hydroxypropyl methyl cellulose has good adhesion, can improve the adhesion between the blast furnace slag particles, makes the blast furnace slag particles and the glass fiber better adhere to each other, and increases the structural strength and the mechanical properties of the blast furnace slag particles.

[0142] The preparation methods of the modified attapulgite in Examples 12-13 do not add modified sawdust and sodium alginate respectively, and the mass ratios of the attapulgite, the modified sawdust and the sodium alginate are changed in Examples 14-15. As can be seen from Table 1, the test effects of the 3d compressive strength, the 28d compressive strength, the 3d flexural tensile strength, the 28d flexural tensile strength, the bonding strength and the impact work resistance of Examples 12-13 are obviously poorer than those of Examples 4-5 and Example 14, and the test effects of the corresponding properties of Example 15 are better than those of Examples 12-13 but poorer than those of Examples 4-5 and Example 14, indicating that the modified sawdust has a porous structure, can be adsorbed on the surface of the attapulgite, increases the heat insulation performance of the attapulgite, the sodium alginate has good stability and adhesion, promotes the adhesion of the attapulgite and the modified sawdust, and improves the material strength, the material stability and the impermeability in the anti-radiation boron-containing cement for nuclear power.

[0143] The preparation methods of the modified wood chips in Examples 16-17 do not add silicon carbide whiskers and starch, respectively. As can be seen from Table 1, the test effects of the compressive strength at 3d, the compressive strength at 28d, the tensile strength at 3d, the tensile strength at 28d, the bonding strength, and the impact resistance of Examples 16-17 are obviously poorer than those of Examples 4-5, but better than those of Example 12, indicating that the silicon carbide whiskers have high strength and high elastic modulus, can be loaded in the structure and pores of the wood chips, and increase the mechanical properties and wear resistance of the wood chips; the starch has good dispersibility, hygroscopicity and adhesion, which helps to bond the wood chips and the silicon carbide whiskers, and increase the performance stability of the wood chips.

[0144] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. A radiation-proof boron-containing cement for nuclear power, characterized in that: The raw materials include, by weight: 325-342 parts of Portland cement, 115-128 parts of boron nitride, 650-662 parts of fine river sand, 226-238 parts of water, 50-60 parts of modified fly ash, 20-30 parts of gypsum, and 40-45 parts of modified attapulgite. The preparation method of the modified fly ash comprises the following steps: (1) Dispersing fly ash in a salicylic acid solution, stirring for 20-25 minutes, washing with water, and then dispersing in a potassium hydroxide solution, stirring for 35-40 minutes, washing with water, and calcining at 340-350°C for 30-35 minutes to obtain pretreated fly ash; (2) dispersing the modified blast furnace slag in deionized water, adding the pretreated fly ash, polyvinyl alcohol and silane coupling agent of step (1), stirring at a temperature of 60-65° C. for 2-3 hours, and filtering to obtain a mixture; (3) spraying nano glue on the surface of the mixture in step (2), drying, and grinding to obtain modified fly ash; Dispersing nano-silica in deionized water, adding polyvinyl alcohol and sodium lauryl sulfate, and stirring evenly to obtain nano glue; The preparation method of the modified blast furnace slag comprises the following steps: washing the blast furnace slag with water to remove impurities, dispersing the blast furnace slag in a sulfuric acid solution, ultrasonically dispersing the slag for 3-4 hours, filtering, washing the slag with water, and then dispersing the slag in a sodium hydroxide solution, ultrasonically dispersing the slag for 1-2 hours, and washing the slag with water to obtain pretreated blast furnace slag; Dispersing the pretreated blast furnace slag in deionized water, adding glass fiber, hydroxypropyl methylcellulose and sodium gluconate, stirring for 4-6 hours, and drying to obtain modified blast furnace slag; The preparation method of the modified attapulgite comprises the following steps: (1) dispersing the attapulgite in a hydrochloric acid solution, washing with water, calcining at 300-320°C for 2-3 hours, then dispersing in deionized water, adding betaine, filtering, and drying to obtain treated attapulgite; (2) Dispersing the modified sawdust in deionized water, adding the treated attapulgite from step (1), stirring at a temperature of 65-70°C for 1-2 hours, adding sodium alginate and barium sulfate, continuing stirring for 1-2 hours, and drying to obtain modified attapulgite; The preparation method of the modified sawdust comprises the following steps: grinding the sawdust, dispersing it in ammonia water, stirring it for 10-15 minutes, washing it with water, and then dispersing it in deionized water, adding silicon carbide whiskers, starch, and sodium hexametaphosphate, stirring it at 70-75° C. for 2-3 hours, and drying it to obtain the modified sawdust.

2. The radiation-proof boron-containing cement for nuclear power according to claim 1, characterized in that: The mass ratio of the fly ash, modified blast furnace slag and nano glue is 1:0.6-0.7:0.2-0.

3.

3. The radiation-proof boron-containing cement for nuclear power according to claim 1, characterized in that: The mass ratio of the attapulgite, the modified sawdust and the sodium alginate is 1:0.4-0.5:0.15-0.25.

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