A method for mix proportion design of serpentine concrete for neutron shielding in high temperature environment

Abstract

The application relates to a mix proportion design method of a high-temperature environment neutron shielding serpentine concrete, which comprises the following steps: S1, calculating a neutron shielding attenuation coefficient of the serpentine concrete; S2, calculating the relationship between the neutron shielding attenuation coefficient of the serpentine concrete and combined water content through experiments; S3, calculating the relationship between cementing materials and aggregate mixing amounts through the combined water content of the concrete; S4, calculating the relationship between the cementing materials and the aggregate through the compressive strength requirement of the concrete; and S5, obtaining a mix proportion calculation formula of the serpentine concrete in a high-temperature environment. Through the thickness requirement of the serpentine concrete in structural design, the neutron shielding requirement and the like, and in combination with relevant physical parameters, the mix proportion design method of the neutron radiation shielding serpentine concrete in a high-temperature environment is provided, and the method has important significance for the development of nuclear engineering.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and specifically relates to a mix design method for neutron-shielded serpentine concrete under high-temperature conditions. Background Technology

[0002] Today, nuclear physics is applied in many fields, including energy and medicine, and is of great significance for achieving low-carbon development and protecting people's health. However, the rise of new nuclear-related facilities has also brought about construction problems, such as how to shield the generated nuclear radiation (neutrons, gamma rays).

[0003] In the field of building materials, aggregates containing bound water are often used to prepare concrete for neutron protection. The most commonly used aggregates containing bound water include serpentine and magnetite. However, gamma rays easily cause a rise in concrete temperature, and the stability of bound water at high temperatures is a crucial consideration. Serpentine, due to its high bound water content (11-18%) and its unique advantages such as maintaining a water loss rate of less than 1% below 600℃, is widely used in the construction of nuclear-related facilities. Current technologies primarily consider how to adapt concrete to these properties from the perspectives of workability and mechanical performance.

[0004] Therefore, how to study a mix design method for neutron-shielded serpentine concrete under high-temperature conditions is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a mix design method for neutron-shielded serpentine concrete under high-temperature conditions. By calculating the content of bound water in serpentine and bound water formed by the chemical reaction of cement in hardened cement paste, the mix proportion of neutron radiation shielding concrete can be precisely controlled.

[0006] To solve the above technical problems, the present invention includes the following technical solutions:

[0007] A mix design method for neutron-shielded serpentine concrete under high-temperature conditions, comprising the following steps:

[0008] Step S1: Calculate the neutron shielding attenuation coefficient σ of serpentine concrete: In the formula, σ is the attenuation coefficient, with units of cm. -1 L represents the thickness of the serpentine concrete, in cm, and M1 represents the neutron flux before concrete shielding, in n / cm². 2 ·s, M2 is the neutron flux after concrete shielding, in units of n / cm². 2 ·s;

[0009] Step S2: Calculate the relationship between the neutron shielding attenuation coefficient and the bound water content of serpentine concrete through experiments: σ=0.038ln(W混 +1)+0.018, Formula (2), where W 混 The content of bound water in concrete, expressed in wt.% (10 ≤ W). 混 ≤20;

[0010] Step S3: Calculate the relationship between cementitious materials and aggregates by calculating the bound water content in concrete: W = w(t), formula (3), where W is the water loss of the neat cement paste at temperature t, in wt.%, 50≤t≤650; the bound water content W in the neat cement paste 净 For: W 净 =w(650)-w(T), formula (4), the relationship between the amount of coarse and fine aggregates and the amount of cementitious materials is: In the formula, X represents the dosage of cementitious material, in kg / m³. 3 Y represents the dosage of coarse and fine aggregates, in kg / m³. 3 Z represents the water content, measured in kg / m³. 3 A represents the bound water content of coarse and fine serpentine aggregates as measured by X-ray fluorescence spectroscopy, in wt.%;

[0011] Step S4: Calculate the relationship between cementitious materials and aggregates based on the concrete compressive strength requirements. In the formula, ρ 胶 ρ is the density of the cementitious material. 骨 f is the density of the aggregate. cus,o f is the required 28-day compressive strength of concrete. ce The compressive strength grade of concrete; and

[0012] Step S5: Combining formulas (5) and (6), we obtain the formula for calculating the mix proportion of serpentine concrete in a high-temperature environment:

[0013]

[0014] Further, step S2 includes: preparing hardened cement paste test blocks with bound water contents of 11.25%, 11.70%, 12.15%, 12.60%, 13.05%, 13.50%, 13.95%, 14.40%, and 14.85% respectively through theoretical calculation; determining the actual bound water content of the nine hardened cement paste samples through thermogravimetric analysis; preparing nine corresponding serpentine concretes; calculating the bound water content of the concretes; conducting neutron radiation tests on the nine concrete samples; and obtaining formula (2) through extensive experiments.

[0015] Further, step S3 includes: soaking the cured hardened cement paste in alcohol for 48 hours, taking it out, evaporating it at room temperature for 24 hours, and determining the bound water content in the concrete cement paste by thermogravimetric analysis to obtain formula (3).

[0016] Further, step S4 includes: [The following is a separate, unrelated statement:] The sum of the volumes of the three raw materials X, Y, and Z is 1m³. 3 Meanwhile, the ratio of water to cementitious materials can be designed according to the strength requirements of concrete, resulting in formula (6).

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] This invention provides a mix design method for serpentine concrete for neutron shielding in high-temperature environments. By considering the thickness requirements of serpentine concrete in structural design and its neutron shielding needs, and combining relevant physical parameters, this invention proposes a mix design method for serpentine concrete for neutron radiation shielding in high-temperature environments, which is of great significance for the development of nuclear-related engineering. The calculated serpentine concrete mix proportion was used to prepare the concrete, and the resulting serpentine concrete underwent neutron radiation shielding tests. The results showed that a 25cm thick layer of this serpentine concrete can reduce the neutron flux shielding to 4.94% of the original amount, meeting the requirements of practical applications. Detailed Implementation

[0019] The mix design method for neutron-shielded serpentine concrete under high-temperature conditions provided by the present invention will be further described in detail below with reference to specific embodiments. The advantages and features of the present invention will become clearer from the following description.

[0020] Example 1:

[0021] The mix design method for neutron-shielded serpentine concrete under high-temperature conditions in this embodiment mainly includes the following steps:

[0022] First, the neutron shielding attenuation coefficient of serpentine concrete is calculated; second, the bound water content of concrete is calculated using the attenuation coefficient; then, the relationship between the cementitious material and aggregate content is calculated based on the bound water content of concrete; finally, the relationship between the cementitious material and aggregate content is calculated based on the concrete compressive strength requirements.

[0023] Finally, the mix proportion calculation formula for neutron-shielded serpentine concrete was obtained.

[0024] The serpentine concrete thickness L is 25cm, and the required neutron flux before concrete shielding is 10. 10 n / cm 2 The neutron flux after shielding is 5 × 10⁻⁶ s. 8 n / cm 2 s, Substitute into formula (1) The calculated neutron attenuation coefficient is 0.12. Substituting this into formula (2)... The required amount of bound water in the concrete was found to be 13.64%.

[0025] Serpentine concrete is subjected to a high temperature of 150℃ for a long time. Substituting into formula (4), we can know that W 净 =w(650)-W(150)=90kg / m 3 .

[0026] X-ray fluorescence spectroscopy revealed that the bound water content of the serpentine coarse and fine aggregates was A = 12.24 wt.%, and the density of the cementitious material was 3000 kg / m³. 3 The density of serpentine aggregate is 2300 kg / m³. 3 The required 28-day compressive strength of the concrete is 22 MPa, and the compressive strength grade of the concrete is 20 MPa.

[0027] Then, by substituting into formula (7), we can obtain:

[0028]

[0029] The calculated serpentine concrete mix proportions were used to prepare the concrete. The resulting serpentine concrete underwent a neutron radiation shielding test. The results showed that a 25cm thick layer of this serpentine concrete could reduce the neutron flux shielding to 4.94% of the original, which meets the requirements of practical applications.

[0030] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. The above embodiments only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A mix design method for neutron-shielded serpentine concrete under high-temperature conditions, characterized in that, The steps include the following: Step S1: Calculate the neutron shielding attenuation coefficient of serpentine concrete. Formula 1, where σ is the attenuation coefficient, in cm. -1 L represents the thickness of the serpentine concrete, in cm, and M1 represents the neutron flux before concrete shielding, in n / cm². 2 ·s, M2 is the neutron flux after concrete shielding, in units of n / cm². 2 ·s; Step S2: Calculate the relationship between the neutron shielding attenuation coefficient and the bound water content in serpentine concrete through experiments. Formula 2, where W 混 This refers to the bound water content in concrete, expressed in wt.%, 10≤W 混 ≤20; Step S3: Calculate the relationship between cementitious materials and aggregates based on the bound water content in the concrete. Formula 3, where W is the water loss of the paste at degree t, in kg / m³. 3 50≤t≤650; bound water content W in neat pulp 净 for: Formula 4 states that the relationship between the dosage of coarse and fine aggregates and the amount of cementitious materials is as follows: Formula 5, where X is the dosage of cementitious material, in kg / m³. 3 Y represents the dosage of coarse and fine aggregates, in kg / m³. 3 Z represents the water content, measured in kg / m³. 3 A represents the bound water content of coarse and fine serpentine aggregates as measured by X-ray fluorescence spectroscopy, in wt.%; Step S4: Calculate the relationship between cementitious materials and aggregates based on the concrete compressive strength requirements. Formula 6, where, Density of cementitious materials The density of the aggregate, The required 28-day compressive strength for concrete. This refers to the compressive strength grade of concrete. Step S5, combining formulas 5 and 6, yields the formula for calculating the mix proportion of serpentine concrete in high-temperature environments: ； 。 2. The method according to claim 1, characterized in that, Step S2 includes: preparing hardened cement paste test blocks with bound water contents of 11.25%, 11.70%, 12.15%, 12.60%, 13.05%, 13.50%, 13.95%, 14.40%, and 14.85% respectively through theoretical calculation; determining the actual bound water content of the nine hardened cement paste samples through thermogravimetric analysis; preparing nine corresponding serpentine concretes; calculating the bound water content of the concretes; conducting neutron radiation tests on the nine concrete samples; and obtaining Formula 2 through extensive experiments.

3. The method according to claim 1, characterized in that, Step S3 includes: soaking the cured cement paste in alcohol for 48 hours, then removing it and allowing it to evaporate at room temperature for 24 hours. The bound water content in the cement paste is determined by thermogravimetric analysis to obtain Formula 3.

4. The method according to claim 1, characterized in that, Step S4 includes: The sum of the volumes of the three raw materials X, Y, and Z is 1m³. 3 Meanwhile, the ratio of water to cementitious materials can be designed according to the strength requirements of concrete, resulting in Formula 6.

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