KR20180133628A - Concrete composite for improving neutron shielding ability - Google Patents

Abstract

A concrete composition for improving neutron shielding ability according to the present invention comprises carbon materials added to cement, aggregate and water to lower the energy of neutrons incident on a concrete structure, thereby increasing the neutron absorption rate due to hydrogen present in the concrete structure.

Description

Technical Field [0001] The present invention relates to a concrete composition for improving neutron shielding performance,

The present invention relates to a concrete composition, and more particularly, to a concrete composition for enhancing the neutron shielding performance of a concrete structure by increasing the neutron absorption rate due to hydrogen present in the concrete structure, thereby improving the neutron shielding performance of the concrete structure.

Recently, with the development of the nuclear industry, various nuclear facilities, such as nuclear power plants and nuclear waste storage facilities, are being built in various places. At this time, in various nuclear facilities, etc., it is necessary to reduce the amount of radiation received by the human body to the utmost, and to prevent structural or material damage by radiation. Accordingly, in recent years, development of a radiation shielding material capable of reliably shielding radiation has been carried out.

On the other hand, the radiation is divided into an alpha ray, a beta ray, a gamma ray and a neutron ray. Alpha and Beta lines can be shielded by common materials with thin permeability and thin concrete or thin. The beta rays and the gamma rays are shielded easily by metals such as lead because they are decelerated and shielded by electrons and shielded by concrete having a certain thickness or more.

However, when lead is used as a shielding material, it is troublesome to carry it because the weight of the lead is considerable, and the concrete structure can not be manufactured in various shapes.

On the other hand, neutrons have a high energy and strong permeability, so if they collide with other materials, gamma rays can be generated and damage various materials such as nuclear power facilities. Accordingly, it is necessary to shield neutrons and gamma rays safely and reliably.

Conventionally, neutrons are shielded by using concrete. However, since the thickness of the concrete shielding wall must be very thick in order to shield the neutron, there is a problem in that it is not suitable for a nuclear facility having a limited volume.

Accordingly, the applicant of the present invention has proposed the present invention in order to solve the above-mentioned problems, and related prior art documents include Korean Patent Laid-Open Publication No. 10-2014-0070639 (entitled "Radiation Shielding Structure, : 2014.06.10.).

An object of the present invention is to provide a concrete composition for enhancing neutron shielding performance capable of increasing the neutron absorption rate due to hydrogen present in a concrete structure by lowering the energy of neutrons incident on a concrete structure made of concrete containing carbon material .

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

According to the present invention, there is provided a method of reducing the energy of a neutron incident on a concrete structure by adding a carbon material to cement, aggregate, and water, thereby reducing the energy of neutrons incident on the concrete structure, This is achieved by a concrete composition for improving the shielding performance.

The carbon material may be provided as a carbon nanotube (CNT) in powder form.

The carbon material may be added in an amount of 0.5 to 1.5 parts by weight based on 100 parts by weight of the cement.

The carbon material may be added after being plasma-treated so as to be smoothly dispersed in the water.

Hydrocarbon radicals (-OH) are bonded to the carbon surface of the carbon material by the plasma treatment to impart hydrophilicity.

The concrete composition may further comprise a high performance fluidizing agent (AD) such that the carbon material is smoothly sprayed from the water.

Wherein the concrete composition further comprises a blast furnace slag (BS) to reduce an increase in the unit water quantity due to the addition of the carbon material, and the carbon material is added to 100 parts by weight of the cement and the blast furnace slag fine powder 0.5 to 1.5 parts by weight may be added.

The concrete composition may include fly ash (FA) instead of the blast furnace slag fine powder, or may include fly ash together with the blast furnace slag fine powder.

The concrete composition may further comprise a boron-containing aggregate, and the boron-containing aggregate may be provided in at least one of colemanite, ferroboron, and calcite.

The concrete composition comprises 320 to 380 kg / m ³ of the Portland cement and 160 to 190 kg / m ^{3 of} the water. The cement is usually Portland cement (OPC), and the aggregate includes fine aggregate and coarse aggregate. 2.0 to 8.0 kg / m ^{3 of} the carbon nanotube, 830 to 900 kg / m ³ of the fine aggregate, 860 to 935 kg / m ^{3 of} the coarse aggregate and 2.0 to 5.0 kg / m ³ of the high performance fluidizer.

The concrete composition for improving the neutron shielding performance of the present invention is a concrete composition for enhancing the neutron shielding performance of a concrete by adding a carbon material in the production of concrete and reducing the energy of neutrons incident on a concrete structure made of concrete containing carbon material, The neutron absorptivity of the concrete structure can be increased and the neutron shielding performance of the concrete structure can be improved.

Also, the concrete composition for improving the neutron shielding performance of the present invention can satisfy the required strength corresponding to the concrete structure because the unit amount required for manufacturing the cement is not required much even if the carbon material is used.

Hereinafter, a concrete composition for improving the neutron shielding performance according to the present invention (hereinafter referred to as a concrete composition) will be described in detail. In the following description, well-known functions or constructions are not described in order to avoid unnecessary obscuration of the present invention.

The concrete composition according to the present invention is characterized in that a carbon material is added to cement, aggregate and water to lower the energy of neutrons incident on the concrete structure thereby to increase the neutron absorption rate due to hydrogen present in the concrete structure .

Meanwhile, the cement according to the present invention may be an ordinary Portland cement (OPC), but is not limited thereto.

As described above, the concrete composition according to the present invention is blended with cement, aggregate, water and carbon materials. For reference, the aggregate includes fine aggregates such as sand and gravel.

More specifically, the concrete composition according to the present invention comprises 320 to 380 kg / m ³ of Portland cement, 160 to 190 kg / m ^{3 of} water, 2.0 to 8.0 kg / m ^{3 of} the carbon nanotubes (carbon material) To 900 kg / m ³ , and the coarse aggregate of 860 to 935 kg / m ³ . At this time, the blending ratio of water and cement is preferably 45 to 55%.

Here, the concrete composition according to the present invention may further comprise a high performance fluidizing agent (AD). The high-performance fluidizing agent is used to improve the properties of the concrete before and after curing, so that the carbon material is well mixed with water. At this time, it is preferable that the high performance fluidizing agent is added in a mixing ratio of 2.0-5.0 kg / m < ³ > in the above concrete composition.

On the other hand, basically, concrete containing cement, aggregate and water contains hydrogen and various elements. These hydrogen and various elements have higher neutron absorption rate as the neutron energy is lower. A carbon material is added to increase the neutron absorption rate due to hydrogen present in the concrete structure produced by the above-described combination.

Meanwhile, the carbon material is provided as a carbon nanotube (CNT) in powder form. In other words, carbon nanomaterials such as carbon nanotubes, carbon nanowires, graphenes, or ordinary carbon such as carbon fibers are milled into powder form and added to the concrete. Concrete structures made of concrete in which carbon material is added to concrete are given strength and elasticity.

Here, as described above, the processing of the carbon material into the powder form is intended to spread the carbon material evenly over the water. However, carbon materials, such as carbon nanotubes, carbon nanowires, graphene, and carbon fibers, are not well dispersed in water even when processed into powder form. Accordingly, the hydrophilicity of the carbon material, that is, the dispersing power of the carbon material in water, should be imparted through a variety of different methods or treatments.

As one of the methods for imparting hydrophilicity to the carbon material as described above, ultrasonic treatment can be applied to the carbon material in powder form so that the carbon material in powder form can be mixed well with water.

In addition, as another method for imparting hydrophilicity to the carbon material, the carbon material can be subjected to plasma treatment. At this time, the carbon material is bonded with a hydroxyl radical (-OH) having a property of reacting with other substances on the carbon surface by the plasma treatment. The carbon material to which the hydroxyl radical is bonded to the surface is hydrophilized, do. Here, the plasma treatment for the carbon material is more preferably an atmospheric pressure spraying method than a chamber method widely used in semiconductor processing.

For reference, in the above description, the carbon material is added to the concrete in the form of powder. However, if necessary, the polymer material or the carbon molding can be used in a form of being poured into a concrete or concrete structure. However, the present invention is not limited thereto.

The carbon material provided as the carbon nanotubes is preferably added in an amount of 0.5 to 1.5 parts by weight (more preferably 0.7 to 1.5 parts by weight) based on 100 parts by weight of the cement. For example, when the cement is 350 kg / m ³ , approximately 1.75-4.6 kg / m ³ of carbon nanotubes are added.

For reference, when the amount of the carbon material added is more than 1.5 parts by weight based on 100 parts by weight of the cement, the compressive strength of the concrete becomes very low, so that it may be difficult to use it as concrete.

Meanwhile, in the concrete composition according to the present invention, the amount of water, that is, the unit water amount is increased according to the amount of the carbon material added. Specifically, as described above, the carbon material added to the concrete is only about 1% of 100 parts by weight of the cement. However, even if the amount of the carbon material added to the cement is added, the volume of the carbon material increases, and the slump of the concrete is lowered. Generally, the amount of water, that is, the unit water quantity, must be increased to meet the slump required for concrete. If the unit water quantity is increased, the compressive strength of the concrete structure itself may be lowered.

Also, the concrete composition according to the present invention may further comprise a blast furnace slag (BS) in order to alleviate an increase in the unit yield due to the addition of the carbon material. The blast furnace slag powder is a latent hydraulic material. When it comes into contact with water, the hydration reaction is not fast, so the fluidity is excellent and the long-term strength is improved. For reference, when blast furnace slag powder is used as a by-product of steel making, the amount of carbon dioxide generated is significantly reduced compared to cement, so it can be environmentally friendly.

Accordingly, the carbon material to be provided as the carbon nanotube in the concrete composition according to the present invention is added in an amount of 0.5 to 1.5 parts by weight (more preferably 0.7 to 1.5 parts by weight) based on 100 parts by weight of the whole cement and blast furnace slag powder desirable. For example, when the total amount of cement and blast furnace slag powder is 350 kg / m ³ , approximately 1.75-4.6 kg / m ³ of carbon nanotubes are added.

Meanwhile, the concrete composition according to the present invention may contain fly ash (FA), which is a material for increasing the fluidity of concrete, instead of blast furnace slag fine powder, or may contain fly ash together with blast furnace slag fine powder. That is, by adding the blast furnace slag fine powder or the fly ash with the carbon material added concrete, the fluidity of the concrete can be increased and the compressive strength can be maintained while reducing the unit quantity used in the mixing of the concrete.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Outline of experiment

Table 1 shows the mixing ratio of the concrete composition to evaluate the neutron shielding performance of the concrete structure made of the concrete containing carbon nanotubes.

Here, water (W): 175 kg / m ³ , cement (C): 350 kg / m ³ , fine aggregate (S): 878 kg / m ³ , coarse aggregate (G): 901 kg / m ³ , (AD): 2.10 kg / m < ^{3 &} gt ;. The water-cement ratio (W / C) was set at 50% and the fine aggregate ratio (S / a) was set at 50%. The carbon nanotube (CNT) was set to 0 to 3.5 kg / m ³ .

In other words, the carbon nanotubes (CNTs) were 0% (Comparative Examples 1 and 2), 0.75% (Examples 1-1 and 2-1), and 1.0% (Example 1- 2, and 2-2). We measured the neutron shielding rate, unit water quantity, slump measurement and air quantity in the laboratory and measured the strength of 3, 7, and 28 days of age to check the compressive strength of the concrete structure.

Coarse aggregate
Maximum exponent
(mm) Water-cement ratio
(%) Fine aggregate rate
S / a
(%) Unit quantity (kg / m ³ ) W C CNT S G AD 25 50 50 175 350 0-3.5 878 901 2.10

2. Experimental Results and Analysis

Table 2 shows the measurement results of neutron shielding rate, unit water quantity, fluidity, air quantity and compressive strength according to the amount of carbon nanotube (CNT) added to concrete in the mixing ratio of Table 1 of the embodiment. For reference, the amount of CNT in Example 1-1 is 2.6 kg / m ^3, that is, 0.75 part by weight with respect to 100 parts by weight of cement (C). In Example 1-2, the amount of carbon nanotubes (CNT) kg / m ^3, that is, 1.0 part by weight based on 100 parts by weight of the cement (C).

Remarks CNT
(cement
substitution%) Neutron shielding rate
(%) usually
Portland cement (%) unit
Quantity
(kg / m ³ ) Slump
(kg / m ³ ) Air
(kg / m ³ ) Compressive strength (kgf / cm ² ) 3 days 7 days 28th Comparative Example
One 0 66.5 100 200 4.9 25.7 34.0 47.1 Example
1-1 0.75 68.0 100 5.0 180 5.8 21.9 27.8 38.8 Example
1-2 1.0 69.0 100 7.0 180 5.2 15.2 20.1 32.9

Referring to Table 2, it can be seen that the neutron shielding ratio is improved as the amount of carbon nanotube (CNT) added increases. In other words, in Examples 1-1 and 1-2 in which the addition amounts of carbon nanotubes (CNTs) were increased to 0.75% and 1.0%, respectively, as compared with Comparative Example 1 in which the addition amount of carbon nanotubes (CNT) was 0% The neutron shielding rate of the reactor was increased to 68.0% and 69.0%, respectively.

Also, it can be seen that the unit water amount is increased as the carbon nanotube (CNT) is added. However, in general, the compressive strength required for a concrete structure of a nuclear power plant and a nuclear waste storage facility satisfies a value of not less than 24 kgf / cm ^{2. In} both of Examples 1-1 and 1-2, cm < ^{2 &} gt ;. For reference, in Comparative Example 1 in which carbon nanotubes were not added, the compressive strength was reduced in Comparative Examples 1-1 and 1-2, but both of Examples 1-1 and 1-2 showed the standard compressive strength It can be seen that it satisfies.

That is, as the amount of carbon nanotubes (CNT) increases in the concrete composition, the compressive strength decreases and the unit water quantity increases, but the neutron shielding ratio increases.

Table 3 shows the measurement results of the neutron shielding rate, unit water quantity, fluidity, air quantity and compressive strength according to the amount of carbon nanotubes (CNT) added in the concrete composition having the blending ratio of Table 1 of the embodiment. At this time, a blast furnace slag fine powder (BS) was added to reduce the unit water used in the concrete to which carbon nanotubes (CNT) were added.

For reference, the amount of carbon nanotubes (CNT) in Example 2-1 was 2.6 kg / m ^3, that is, 0.75 part by weight with respect to 100 parts by weight of the whole cement (C) and blast furnace slag fine powder (BS) -2, the amount of carbon nanotubes (CNT) is 3.5 kg / m ^3, that is, 1.0 part by weight with respect to 100 parts by weight of the total of the cement (C) and the slag fine powder (BS). Also, ordinary Portland cement (OPC) and blast furnace slag fine powder (BS) are blended in a general ratio of 60:40%.

Remarks CNT
(cement
substitution%) Neutron shielding rate
(%) usually
Portland cement
(%) Blast furnace slag
Fine powder
(%) unit
Quantity
(kg / m ³ ) Slump
(kg / m ³ ) Air
(kg / m ³ ) Compressive strength (kgf / cm ² ) 3 days 7 days 28th Comparative Example
2 0 66.5 60 40 -5.6 195 5.2 23.5 29.1 39.2 Example
2-1 0.75 68.0 60 40 0.0 180 5.0 15.3 21.3 36.3 Example
2-2 1.0 69.0 60 40 2.0 175 5.0 13.5 19.2 30.3

Referring to Table 3, it can be seen that the neutron shielding ratio is improved as the amount of carbon nanotubes (CNT) is increased. That is, as the addition amounts of the carbon nanotubes increased to 0.75% and 1.0%, respectively, as compared with Comparative Example 2 where the addition amount of the carbon nanotubes was 0%, the neutron shielding ratios of Examples 2-1 and 2-2 were 68.0 %, And 69.0%, respectively.

In addition, it can be seen that the water added, that is, the unit water, is reduced as the slag fine powder (BS) is added, as compared with the above-described Comparative Example 1, Example 1-1, and Example 1-2. Of course, as the slag fine powder (BS) was added, the compressive strength of the concrete of Comparative Example 2, Example 2-1 and Example 2-2 was higher than that of Comparative Example 1, Examples 1-1 and 1-2 described above But the amount of added water, that is, the amount of unit water, was measured to be reduced.

At this time, since the compressive strength of each of Examples 2-1 and 2-2 was measured to be not less than 24 kgf / cm ² , both of Examples 2-1 and 2-2 are usually used for a nuclear power plant, a nuclear waste storage facility It is found that the compressive strength required for the concrete structure is satisfied.

For reference, in Examples 2-1 and 2-2, ordinary portland cement and blast furnace slag fine powder were blended in a ratio of 60:40%, but in Examples 1-1 and 1-2, 2 and the neutron shielding ratio were measured in the same manner. This is because the blast furnace slag powder added to Examples 2-1 and 2-2 is added to mitigate an increase in the unit yield due to the addition of the carbon material and is not a material affecting the neutron shielding, It becomes irrelevant.

As can be seen from the above experimental results, it can be seen that the neutron shielding ratio increases as the amount of carbon material, that is, carbon nanotube (CNT), is increased.

Meanwhile, the concrete composition according to the present invention may further comprise an aggregate containing boron (hereinafter referred to as 'boron-containing aggregate'). Boron, together with hydrogen or cadmium, is known as a representative element for shielding neutrons. Accordingly, by adding boron-containing aggregate to the concrete composition in addition to the carbon material, it is possible to achieve neutron shielding effect by boron as well as the above-described effect of improving the neutron shielding performance by hydrogen, thereby further improving the overall neutron shielding performance . At this time, the boron-containing aggregate may be provided as at least one of colemanite, ferroboron and calcite.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. something to do. Accordingly, the true scope of the present invention should be determined by the following claims.

Claims (10)

And a carbon material is added to cement, aggregate and water to lower the energy of neutrons incident on the concrete structure thereby to increase the neutron absorption rate due to hydrogen present in the concrete structure. Concrete composition.
The method according to claim 1,
Wherein the carbon material is provided as a carbon nanotube (CNT) in powder form.
3. The method according to claim 1 or 2,
Wherein the carbon material is added in an amount of 0.5 to 1.5 parts by weight based on 100 parts by weight of the cement.
3. The method according to claim 1 or 2,
Wherein the carbon material is added after being plasma-treated so as to be smoothly dispersed in the water.
5. The method of claim 4,
Wherein the carbon material is hydrophilized by binding a hydroxyl radical (-OH) to the carbon surface by the plasma treatment to impart the hydrophilic property to the carbon material.
3. The method according to claim 1 or 2,
Wherein the concrete composition further comprises a high performance fluidizing agent (AD) to smoothly inject the carbon material from the water.
3. The method according to claim 1 or 2,
The concrete composition further comprises a blast furnace slag (BS) to reduce an increase in the unit quantity due to the addition of the carbon material,
Wherein the carbon material is added in an amount of 0.5 to 1.5 parts by weight based on 100 parts by weight of the cement and the blast furnace slag fine powder as a whole.
8. The method of claim 7,
Characterized in that the concrete composition comprises fly ash (FA) instead of the blast furnace slag fine powder or fly ash together with the blast furnace slag fine powder.
3. The method according to claim 1 or 2,
Wherein the concrete composition further comprises a boron-containing aggregate,
Wherein the boron-containing aggregate is provided as at least one of colemanite, ferroboron and calcite. 2. The concrete composition according to claim 1, wherein the boron-containing aggregate is at least one of colemanite, ferroboron and calcite.
3. The method of claim 2,
The cement is usually Portland Cement (OPC)
The aggregate includes a fine aggregate and a coarse aggregate,
Wherein the concrete composition comprises 320 to 380 kg / m ³ of the Portland cement, 160 to 190 kg / m ^{3 of} water, 2.0 to 8.0 kg / m ^{3 of} the carbon nanotube, 830 to 900 kg / m ³ of the fine aggregate, 860 to 935 kg / m ³ and 2.0 to 5.0 kg / m ³ of a high performance fluidizer.