KR101341179B1 - Concrete composition having impact resistance under high velocity impact - Google Patents

Abstract

The present invention provides an amorphous steel fiber reinforcing concrete composition comprising: a binder, aggregate, water and amorphous steel fiber, wherein 4-5 wt% of carbon, 0.4-0.8 wt% of carbon silicon, 0.1-0.2 wt% of phosphorus and 94-95 wt% of iron are included. When a user uses the amorphous steel fiber reinforcing concrete composition of the present invention, compressive strength, flexural strength, tensile strength and impact resistance are enhanced. [Reference numerals] (AA) Amorphous steel fiber - non-corrosive;(BB) General steel fiber-corrosion

Description

Concrete composition having impact resistance against high impact

The present invention relates to a concrete composition having impact resistance against high speed impact.

In recent years, research on countermeasures against damage caused by extreme impact loads has emerged as a major research field, such as the bombing of the Yeonpyeong Island and the explosion of Fukushima nuclear power plants in Japan. In addition, due to the large size of structures and facilities, there is a high possibility of numerous casualties and property damage due to one accident in case of extreme impact load, and not only damage damage caused by impact but also fire and high temperature environment added by impact and explosion. Consideration should also be given to problems with secondary damage, such as exposure.

Conventionally, high toughness explosion-proof cement composites using composite fibers are used as disclosed in Korean Patent No. 10-0945204. However, when the composite fibers used in the registered patent are corroded by moisture and salt due to the use of conventional steel fibers, There is a problem that there is a high possibility of causing expansion within the cured body to cause cracks.

One aspect of the present invention is to provide a concrete composition having excellent impact resistance against compressive strength, flexural strength, tensile strength and high-speed impact by adding amorphous steel fibers excellent in corrosion resistance and tensile strength compared to general steel fibers.

According to one embodiment of the present invention, the binder, aggregate and amorphous steel fibers, wherein the amorphous steel fibers 4 to 5 wt% carbon, 0.4 to 0.8 wt% silicon, 0.1 to 0.2 wt% phosphorus and 94 to 95 wt iron An amorphous steel fiber reinforced concrete composition is provided that comprises%.

The concrete composition may be one in which the amorphous steel fibers are incorporated in 0.02 ~ 0.9 vol% of the total volume of the concrete composition.

The concrete composition may be 5 to 40% by weight of the binder, 40 to 80% by weight of aggregates and 5 to 40% by weight of water.

The amorphous steel fiber may have a length of 10 to 35 mm.

The tensile strength of the amorphous steel fiber may be 1200 ~ 1800MPa.

The concrete composition may further comprise 0.01 to 2.0% by weight of a reducing agent.

By using the concrete composition reinforced with the amorphous steel fibers of the present invention, the compressive strength, the flexural strength, the tensile strength and the impact resistance can be improved.

1 illustrates an amorphous steel fiber incorporated in an embodiment of the present invention.
Figure 2 shows the corrosion of amorphous steel fibers and ordinary steel fibers incorporated in the examples and comparative examples of the present invention.
Figure 3 shows the back peeling thickness of the Examples and Comparative Examples of the present invention with different types and mixing ratio of steel fibers.
Figure 4 shows the back peeling area loss rate of the Examples and Comparative Examples of the present invention with different types and mixing ratio of steel fibers.
Figure 5 shows the impact resistance evaluation results of the Examples and Comparative Examples of the present invention with different types and mixing ratio of steel fibers.

The present invention relates to a concrete composition having impact resistance against high speed impact. When using the concrete composition containing the amorphous steel fibers of the present invention, it is possible to produce concrete excellent in compressive strength, flexural strength, tensile strength and impact resistance.

According to one embodiment of the present invention, the binder, aggregate, water and amorphous steel fibers, wherein the amorphous steel fibers 4 to 5 wt% carbon, 0.4 to 0.8 wt% silicon, 0.1 to 0.2 wt% phosphorus and 94 to 95 iron An amorphous steel fiber reinforced concrete composition is provided comprising wt%.

The amorphous steel fiber, when solidified in the molten state of the metal, has a disordered atomic arrangement because atoms do not have time to regularly arrange and crystallize when cooled at a speed higher than a critical cooling rate. It shows excellent characteristics such as.

In addition, since the amorphous steel fiber has to be cooled at a high speed in order to have the above characteristics, it is manufactured in an ultra-thin plate having a width of 1 to 2 mm and a thickness of 0.002 to 0.004 mm. Thus, more individuals can be incorporated at the same incorporation rate as compared to ordinary steel fibers. As a result, by using the concrete composition comprising the amorphous steel fibers of the present invention it is possible to produce concrete having excellent flexural strength, tensile strength and impact resistance than concrete mixed with ordinary steel fibers.

The amorphous steel fiber may be incorporated at 0.02 to 0.9 vol% of the total volume of the concrete composition. If it is less than 0.02 vol%, the effect of reinforcing the tensile strength due to the mixing of amorphous steel fibers cannot be expected, and if it exceeds 0.9 vol%, fiber aggregation occurs. More preferably, 0.05 to 0.8 vol% may be mixed, and most preferably, 0.1 to 0.6 vol% may be mixed.

The concrete composition is not particularly limited, but may include 5 to 40 wt% of the binder, 40 to 80 wt% of the aggregate, and 5 to 40 wt% of the water. If the composition of each composition is out of the above range it is difficult to ensure the durability of the concrete, cracking of the concrete may occur.

The length of the amorphous steel fiber is not particularly limited, but may be an average of 10 to 35 mm. If less than 10mm, the length of the binder can be attached is too short, the flexural strength and tensile strength reinforcing effect of the concrete is weak, if it exceeds 35mm may cause a problem in dispersibility may worsen the workability. More preferably, it may be 15-30 mm, and most preferably 18-26 mm.

In addition, the tensile strength of the amorphous steel fiber is not particularly limited, but may be 1200 ~ 1800Mpa. Since the amorphous steel fiber has excellent tensile strength compared to general steel fiber having a tensile strength of 1100 to 1150 MPa, when the concrete composition of the present invention is used, it may have excellent tensile strength and impact resistance compared to concrete incorporating general steel fiber.

The concrete composition may further comprise 0.01 to 2.0% by weight of a reducing agent to improve workability and durability. If it is out of the above range, the workability of the concrete is inferior, and the durability is weakened. The sensitizer may be an AE sensitizer, but is not limited thereto, and any sensitizer used by those skilled in the art may be used.

The binder may comprise any one or a combination of blast furnace slag, fly ash and cement. As the weight ratio of the blast furnace slag and fly ash is greater, the exothermic rate is reduced and temperature rise is suppressed, and concrete having excellent fluidity, water tightness, and salt shielding property can be obtained.

The concrete composition may have a blending ratio (W / B) of water and a binder of 35 to 65%. If less than 35%, the hydration reaction of the cement does not occur sufficiently to reduce the compressive strength inside the concrete structure, and if it exceeds 65%, the strength of the concrete decreases because evaporated water remains as voids in the concrete structure. More preferably, it may be 40 to 60%, most preferably 46 to 54%.

The aggregates include coarse aggregates that pass 100% of the standard mesh 5mm sieves and coarse aggregates that remain 100% in the standard mesh 5mm sieves, and the percentage of the absolute volume of fine aggregates relative to the sum of the absolute volumes of fine aggregates and coarse aggregates It is called (S / a).

The aggregate may have a fine aggregate (S / a) of 40 to 70%, if less than 40% of the coarse aggregate of the concrete composition increases dry shrinkage cracking, but the workability worsens, if more than 70% Increased dry shrinkage, settlement cracking and plastic shrinkage cracking of concrete mixes. More preferably, it may be 46 to 64%.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

[Example]

1. Preparation of amorphous steel fiber

In the amorphous steel fiber according to the embodiment of the present invention, the molten iron produced in the blast furnace of the steel mill was used as an alloy of the base metal. The molten iron was prepared by receiving a torpedo car, and then Fe-Si alloy iron and Fe-P alloy iron were added to have a composition suitable for producing amorphous steel fibers, and the molten iron was 4.4 wt% carbon and 0.55 wt% silicon. , 0.15 wt% phosphorus and 94.9 wt% iron.

The molten iron added with iron alloy may be charged into a tundish and then blown with a gas such as pure oxygen or mixed oxygen or air or a solid oxide such as iron oxide or manganese oxide if necessary to control the carbon concentration. .

In addition, in order to control the temperature of the molten iron in a tundish, the temperature of the molten metal was optimized using the temperature raising apparatus provided in the tundish itself. Amorphous steel fibers were prepared by injecting the prepared molten metal into a metal mold, and cooling and solidifying at a cooling rate of at least 100 ° C./sec or more. The amorphous steel fiber was 1.6 mm wide and 0.0029 mm thick, and the amorphous steel fiber was cut into lengths of 10 mm and 30 mm. (Hereinafter, 10 mm amorphous steel fiber is referred to as AF10 and 30 mm amorphous steel fiber as AF30.)

2. Comparison of specifications and corrosion resistance evaluation of general steel fiber and amorphous steel fiber

In this embodiment, BUNDREX (length 30 mm, hereinafter referred to as SF30) sold by Steel Fiber Co., Ltd. was used as general steel fiber. Specifications for amorphous steel fibers AF30, AF10, and the number and specific surface area of the steel fibers and amorphous steel fibers when 1.0 vol% was mixed in 1 lb of concrete are shown in Table 1 below.

division 1 fiber standard 1 lb 1.0 vol.% Incorporated Length
(Mm) diameter
(Mm) width
(Mm) thickness
(Mm) Specific surface area
(Mm2) Number of mixed objects
(dog) Specific surface area
(Mm2) SF30 30 0.5 - - 47.1 1,560,000 43,476,000 AF30 30 - 1.6 0.0029 48 7,200,000 345,600,000 AF10 10 - 1.0 0.0024 10 41,760,000 417,600,000

In addition, the corrosion resistance of the general steel fibers and amorphous steel fibers were evaluated using the tensile strength test method of KS F 2565 concrete steel fibers. The tensile strength of the general steel fiber SF30 was 1200MPa, and the tensile strength of the amorphous steel fiber AF30 was 1400MPa. After exposing the general steel fiber SF30 and amorphous steel fiber AF30 to water for 30 days, 60 days, and 90 days, respectively, the tensile strength residual ratio of the steel fiber not exposed to water was measured and shown in Table 2 below. A photo showing whether it is generated is shown in FIG. 2.

division Amorphous steel fiber Plain steel fiber 30 days 60 days 90 days 30 days 60 days 90 days The tensile strength
Residual rate (%) 101 99 99 94 92 92

3. Manufacture of concrete test body

[Examples 1 to 3]

Based on 1 m3 of concrete, binders 331 kg / m3 mixed with a weight ratio of cement 90 and blast furnace slag 10, aggregates 1777 kg / m3 (grain aggregates 855 kg / m3, coarse aggregates 922 kg / m3), water 173 kg / m3 And AE water reducer 1.65 kg / m 3 were mixed. The blending ratio (W / B) of the mixture was set to 52.3%, and the aggregate aggregate ratio (S / a) was set to 48.2%.

Thereafter, the amorphous steel fiber AF10 was mixed so as to be 0.25%, 0.5%, and 0.75% of the total volume of the mixture, respectively, to prepare Examples 1 to 3, which were concrete test bodies having a width of 100 mm, a length of 100 mm, and a height of 30 mm.

[Examples 4 to 6]

Examples 4 to 6, which were concrete test bodies under the same conditions as in Example 1, were prepared except that amorphous steel fiber AF30 was mixed so as to be 0.25%, 0.5%, and 0.75% of the total volume of the mixture, respectively.

Comparative Example 1

Except that the reinforcing fibers were not mixed, Comparative Example 1, which is a concrete test body under the same conditions as in Example 1, was prepared.

[Comparative Examples 2 and 3]

Comparative Examples 2 and 3, which were concrete test bodies under the same conditions as in Example 1, were prepared except that the general steel fibers SF30 were mixed so as to be 0.5% and 1.0% of the total volume of the mixture, respectively.

[Comparative Example 4]

Comparative Example 4, which was a concrete test body under the same conditions as in Example 1, was prepared except that amorphous steel fiber AF10 was mixed so as to be 1.0% of the total volume of the mixture.

4. Evaluation of mechanical properties

Compressive strength, flexural strength and tensile strength of the prepared Examples 1 to 6 and Comparative Examples 1 to 4 were measured, and are shown in Table 3 below.

division Fiber length
(Mm) Fiber mixing rate
(vol.%) Compressive strength
(MPa) Flexural strength
(MPa) The tensile strength
(MPa) Amorphous steel fiber Example 1 10 0.25 50.10 6.56 4.32 Example 2 0.5 51.20 7.46 4.44 Example 3 0.75 53.00 9.53 4.72 Example 4 30 0.25 50.68 7.16 4.23 Example 5 0.5 49.16 11.00 4.98 Example 6 0.75 51.38 13.86 5.34 No marriage Comparative Example 1 - - 55.68 6.51 3.98 Plain steel fiber Comparative Example 2 30 0.5 43.83 8.5 3.98 Comparative Example 3 1.0 47.47 9.61 4.13 Amorphous steel fiber Comparative Example 4 10 1.0 35.65 6.48 3.5

5. Impact resistance evaluation

The impact resistance experiments of the prepared examples and comparative examples were carried out at a condition of an impact rate of 350 kPa using a non-human body having a diameter of 10 mm. The peel back thickness according to the fiber mixing rate of each Example and Comparative Example is shown in Figure 3, the back peeling area loss ratio according to the fiber mixing rate of each Example and Comparative Example is shown in FIG. In addition, the impact resistance evaluation results of Examples and Comparative Examples are shown in FIG.

As can be seen from Table 1, the amorphous steel fiber is ultra-lightweight, ultra-thin plate compared to the general steel fiber, when 1.0 vol% is mixed in 1lb of concrete, the number of mixed objects is about 4.6 times compared to the general steel fiber, AF10 is about 26.8 You can see many more times. As the number of mixed objects increases, the specific surface area AF30 is about 4.7 times wider and AF10 is about 5.7 times wider.

As can be seen from Table 2, when the normal steel fiber is exposed to moisture, it can be confirmed that the corrosion occurs and the tensile strength is reduced to about 90%, but in the case of amorphous steel fiber to maintain 99% tensile strength bar , Amorphous steel fiber has better corrosion resistance than general steel fiber. On the other hand, when the amorphous steel fiber was exposed to moisture for 30 days, the residual ratio of 101% was judged to be caused by the variation of the test specimen.

As can be seen from Table 3 in relation to the evaluation of the mechanical properties, it can be seen that as the fiber mixing rate increases, the compressive strength, the bending strength, and the tensile strength increase. In addition, in the case of Example 5 and Comparative Example 2 having the same fiber length and mixing rate, Example 5 incorporating amorphous steel fibers shows better compressive strength, bending strength and tensile strength, so that the concrete of the present invention mixed with amorphous steel When using the composition it can be seen that it has excellent physical properties compared to the concrete composition incorporating ordinary steel fibers.

On the other hand, in Comparative Example 4 in which 1.0 vol% of amorphous steel fibers (10 mm) were mixed, Examples 1 to 3 and 1.0 vol% of common steel fibers (30 mm) were mixed with the same amorphous steel fibers (10 mm). It can be seen that it has poor physical properties compared to Example 4. This is because amorphous steel fibers are mixed with more populations at the same mixing ratio than general steel fibers, resulting in a decrease in workability such as fiber agglomeration.

3 and 4, in the case of Comparative Example 1, in which the reinforcing fibers were not mixed, the through breakage occurred, but in the Examples and Comparative Examples in which the reinforcing fibers were mixed, the back peeling thickness increased as the fiber mixing rate increased. And it can be seen that the loss of back peeling area is greatly reduced. In addition, when comparing the same Example 2, Example 5 and Comparative Example 2 with the fiber mixing rate of 0.5 vol%, Example 2 incorporating amorphous steel fibers (10 mm) in the back peeling thickness and the back peeling area loss rate was the best. And Comparative Example 2 incorporating ordinary steel fiber (30 mm) was the lowest. Therefore, it can be seen that concrete mixed with amorphous steel fibers has better impact resistance than concrete mixed with ordinary steel fibers, and that even though the same amorphous steel fiber mixing ratio is used, the specific surface area is increased and the reinforcing effect is increased when using shorter steel fibers. have. This can be confirmed with the naked eye through Figure 5 showing the impact performance evaluation results of the Examples and Comparative Examples.

As can be seen from this, concrete having excellent corrosion resistance and impact resistance can be produced using the concrete composition incorporating the amorphous steel fiber of the present invention.

Claims (6)

A binder, aggregate, water and amorphous steel fibers, wherein the amorphous steel fibers include 4-5 wt% carbon, 0.4-0.8 wt% silicon, 0.1-0.2 wt% phosphorus and 94-95 wt% iron, the amorphous steel fibers Is amorphous steel fiber reinforced concrete composition that is incorporated at 0.02 ~ 0.9 vol% of the total volume of the concrete composition. delete The amorphous steel fiber reinforced concrete composition according to claim 1, wherein the concrete composition comprises 5 to 40 wt% of the binder, 40 to 80 wt% of the aggregate, and 5 to 40 wt% of the water. The amorphous steel fiber reinforced concrete composition of claim 1, wherein the amorphous steel fibers have an average length of 10 to 35 mm. The amorphous steel fiber reinforced concrete composition according to claim 1, wherein the tensile strength of the amorphous steel fiber is 1200 to 1800 MPa. The amorphous steel fiber reinforced concrete composition of claim 1, wherein the concrete composition further comprises 0.01 to 2.0% by weight of a water reducing agent.

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