WO2018174430A1 - Steel fiber and fiber reinforced concrete composite including same - Google Patents

Abstract

The present invention relates to a steel fiber and fiber reinforced concrete including the same. A fiber reinforced concrete composite according to the present invention comprises: cement; 20 to 30 parts by weight of an admixture of zirconium-containing silica fine powder having a specific surface area of 85,000 to 120,000 cm2/g and metakaolin having a specific surface area of 10,000 to 20,000 cm2/g mixed at a ratio of between 2:1 and 3:1 with respect to 100 parts by weight of the cement; 100 to 130 parts by weight of sand with respect to 100 parts by weight of the cement; 10 to 25 parts by weight of stone flour having a fineness of 3,000 to 4,000 cm2/g with respect to 100 parts by weight of the cement; and steel fiber, wherein the steel fiber is blended in an amount that is 2 to 5% of the total volume, is coated with copper (Cu), has a diameter of 0.2 to 0.5 mm, a length of 10 to 15 mm, a tensile strength of 2,500 to 3,000 MPa, and is in a coil spring type.

Description

Steel fiber and fiber reinforced concrete composite comprising the same

The present invention relates to a steel fiber and a fiber reinforced concrete composite comprising the same.

More specifically, the present invention relates to steel fibers for concrete and fiber-reinforced concrete composites thereof having been modified in shape to increase the surface area.

Concrete is widely used around the world as an economical and durable material.

However, conventional concrete has problems of low tensile strength and flexural strength and easy cracking.

In order to solve this problem, conventionally, steel fibers were mixed and used in concrete.

However, conventional concrete using steel fibers has a problem that the cost of steel fibers is very expensive and economical, and the destruction of the interface area between cement and aggregate or steel fibers occurs.

In order to solve the above problems, the present invention is to provide a steel fiber for concrete and a fiber-reinforced concrete composite containing the same by increasing the surface area by processing in the spring (Spring) form or twisted form.

Fiber-reinforced concrete composite according to the present invention is a cement, a zirconium-containing silica fine powder having a specific surface area of 85,000 ~ 120,000cm2 / g relative to 100 parts by weight of the cement and metakaolin having a specific surface area 10,000 ~ 20,000 cm2 / g 2: 1 ~ 20 to 30 parts by weight of admixture mixed in a ratio of 3: 1, 100 to 130 parts by weight of sand relative to 100 parts by weight of cement, and 10 to 25 parts by weight of stone powder having 3,000 to 4,000 cm2 / g of powder to 100 parts by weight of cement To include, the steel fiber is blended 2 to 5% of the total volume, the copper (Cu) coating, the diameter is 0.2 ~ 0.5mm, the length is 10 ~ 15mm, the tensile strength is 2,500 ~ 3,000Mpa, It may be characterized by being a coil spring type.

In addition, the steel fiber may have a pitch greater than an inner diameter.

In addition, the steel fiber may have an inner diameter greater than a thickness.

In addition, the steel fiber may have an inner diameter larger than that of the sand.

Another fiber-reinforced concrete composite according to the present invention is a cement, a zirconium-containing silica fine powder having a specific surface area of 85,000 ~ 120,000cm2 / g compared to 100 parts by weight of the cement and metakaolin having a specific surface area of 10,000 ~ 20,000 cm2 / g 2: 1 20 to 30 parts by weight of admixture mixed at a ratio of 3 to 1, 100 to 130 parts by weight of sand relative to 100 parts by weight of cement, and 10 to 25 parts by weight of stone powder having a 3,000 to 4,000 cm2 / g of powder to 100 parts by weight of cement; A first portion having a plate shape, a second portion having a plate shape, and having a cross section intersecting with a cross section of the first portion, and the first portion and the steel fiber. Located between the second portion, it may include a torsion part (Torsion Part) having a twisted shape.

In addition, the length of the twist portion may be shorter than the length of the first portion and the length of the second portion.

In addition, the steel fiber is copper (Cu) coating, 2 to 5% of the total volume is compounded, copper (Cu) coating, the tensile strength may be 2,500 ~ 3,000Mpa.

The present invention by increasing the surface area by processing the steel fibers contained in the concrete in the form of a spring or twisted, there is an effect of improving the bonding strength of the steel fibers and concrete composite.

The present invention has the effect of improving the mechanical performance, such as bending strength, tensile strength of the fiber reinforced concrete composite.

The present invention has an effect of improving the economics by using a zirconium-containing silica-based fine powder and metakaolin mixture in place of expensive silica fume.

The present invention uses a mixture of fine zirconium-containing silica-like powder and metakaolin, including dust generated in the process of electromelting zirconium sand at 800 degrees or higher, to replace expensive silica fume, thereby reducing the viscosity of the concrete composite without deteriorating strength and performance. Lowering the mixing time can be shortened, and workability can be improved.

The present invention can prevent the destruction of the interface area between the cement paste and the aggregate or the interface area between the cement paste and the steel fiber by using the stone powder together with the steel fiber. In addition, there is an effect that can improve the dispersibility of the steel fiber in the concrete composite, thereby improving the mechanical performance of the concrete composite.

1 to 5 are views for explaining the steel fiber of the coil spring form.

6 to 9 are views for explaining the steel fiber in the form of a plate.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the steel fiber and the fiber reinforced concrete composite comprising the same.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. It is not intended to limit the invention to the specific embodiments, it can be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing the present invention, terms such as first and second may be used to describe various components, but the components may not be limited by the terms. The terms may be used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The term and / or may include a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected or connected to that other component, but other components may be present in between. Can be understood. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it may be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions may include plural expressions unless the context clearly indicates otherwise.

In this document, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It may be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries may be interpreted to have meanings consistent with the meanings in the context of the related art, and shall be interpreted in ideal or excessively formal meanings unless expressly defined in the present application. It may not be.

In addition, the following embodiments are provided to more fully describe those skilled in the art, and the shape and size of elements in the drawings may be exaggerated for clarity.

In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description may be omitted.

Example 1

This example is to analyze the effects of the zirconium-containing silica-based fine powder and metakaline presented in the present invention on the fiber reinforced concrete composite.

Table 1 shows the data on the compressive strength measured while varying the zirconium-containing silicate powder to 0, 5, 10, 20, 25, 30, 40 parts by weight based on 100 parts by weight of cement.

In addition to the fine zirconium-containing silica powder, cement is mixed with 20 parts by weight of quartz powder filler to 100 parts by weight of cement and 110 parts by weight of quartz sand having a particle size of 5 mm or less.

Then, the mixed material is mixed evenly for 6 minutes at a speed of 30rpm, mixed for 10 minutes at 100rpm so that the proportion of the blended water binder is 0.2, then mixed for 3 minutes at a speed of 50rpm and then 0.2mm in diameter, 13mm in length (Use the existing straight steel fiber) is added to 2% of the total volume and mixed for 3 minutes at a speed of 40rpm to produce a fiber reinforced concrete composite.

The prepared concrete composites were subjected to viscosity and slump flow tests by the following method, to prepare cylindrical specimens of Ø100 × 200 mm, to undergo wet curing for 2 days, and to steam curing at 90 ° for 3 days, and then to KSF 2405. The compressive strength was measured accordingly.

 Quality of Zirconium-Containing Silica Powder

Item	Fine Zirconium-Containing Silica Powder	Metakaolin	Silica fume	KS F 2567
cm 2 / g	87,000	10,000	200,000	More than 150,000
SiO 2 (%)	94.8	46.5	96.2	85 or more
MgO (%)	-	0.70	1.72	5.0 or less
SO 3 (%)	-	0.65	0.41	3.0 or less
ZrO 2 (%)	3.9	-	-	-
Ignition loss (%)	0.11	1.38	1.62	5 or less
Density (g / cm 3 )	2.38	2.18	2.2	-

Viscosity test was carried out using a Brookfieid viscometer using a Linder spindle, and the slump flow was measured by the diameter of the circular spread in a circular shape by KS F 2594. Firing with increasing use of fine zirconium-containing silica powder The reduced viscosity resulted in the lowest plastic viscosity of 205 Pas when 25% of zirconium-containing silica powder was used.

 Characterization of Fiber Reinforced Concrete Composites

Kinds		0 %	5%	10%	20%	25%	30%	40%
Zirconium-containing silica fine powder	Plastic viscosity (Pa s)	259	253	245	238	220	229	250
	Slump Flow (mm)	550	600	620	634	645	652	648
	Compressive strength (MPa)	157	165	172	186	191	187	167
Silica fume	Plastic viscosity (Pa s)	259	269	272	284	290	298	307
	Slump Flow (mm)	550	552	567	573	598	601	609
	Compressive strength (MPa)	157	182	201	215	217	219	192

As shown in Table 2, as the zirconium-containing silica fine powder content increases, the plastic viscosity decreases and the slump flow increases. At 25%, the plastic viscosity is the lowest, while the compressive strength is the maximum value. On the other hand, when silica fume is used, the firing viscosity increases and the increase in slump flow is insignificant. Therefore, the use of silica fume can be seen as a disadvantage in terms of workability.

In order to analyze the effect of mixing the zirconium-containing silica fine powder and metakaolin shown in Table 3, the total amount of the mixture was fixed at 25 based on 100 parts by weight of cement, and the ratio of the zirconium-containing silica fine powder and metakaolin was 1. : 1, 2: 1, 3: 1, 4: 1 parts by weight, 20 parts by weight of the quartz powder filler, 110 parts by weight of quartz sand with a particle size of 5mm or less, evenly mixed for 6 minutes at a speed of 30rpm , Mix for 10 minutes at 100rpm so that the proportion of water mixture is 0.2, and then mix again for 3 minutes at a speed of 50rpm, and then add 2% of 0.2mm diameter and 13mm length steel fiber (using conventional straight steel fiber) to 40rpm The fiber reinforced concrete composite was prepared by mixing at a speed of 3 minutes, and the viscosity and slump flow test was performed by the following method, and a cylindrical specimen of Ø100 × 200 mm was produced and wetted for 2 days. Performing production, which was measured for compressive strength according to performed for 3 days and then steam curing at 90 ° KSF 2405.

Characterization of Fiber Reinforced Concrete Composites (2)

Kinds	Metakaolin	1: 1	2: 1	3: 1	4: 1	Metakaolin 0%
Zirconium-containing silica fine powder	Plastic viscosity (Pas)	215	200	204	216	220
	Slump Flow (nm)	652	662	660	650	645
	Compressive strength (MPa)	208	218	220	210	191

As shown in Table 3, the use of 100 parts by weight of silica powder containing 100 parts by weight of zirconium-containing silicate powder replaced the metakaolin in part, resulting in lower plastic viscosity and increased slump flow, resulting in better workability. Increased. However, the ratio of the fine zirconium-containing silica powder and metakaolin was changed from 1: 1 to 4: 1. The compressive strength tended to be higher than that of using only zirconium-containing silica-based fine powder, and showed higher compressive strength than that of silica fume.

Example 2

This example is to analyze the effect of the finely divided powder with a powder degree of 2,000 ~ 4,500cm2 / g proposed in the present invention on the fiber reinforced concrete composite.

In Example 1, the mixture of the finely mixed zirconium-containing silica-like powder and metakaolin 2: 1 was fixed to 25 by weight of cement, and the powder degree was 2,000 to 4,500 cm 2 instead of 20 parts by weight of the quartz powder filler. We tried to find out the characteristics of the fine powders with / g by replacing them with various forms and the characteristics according to the mixing ratio of the fine powders. 110 parts by weight of quartz sand with a particle size of 5 mm or less and steel fibers were tested in the same manner.

 Characteristics of Fiber Reinforced Concrete Fusion with Different Powder Levels

Stone powder	Slump Flow (mm)	Fiber dispersion	Compressive strength (MPa)	Flexural strength (MPa)
2,000	649	usually	174	35
2,500	630	usually	198	42
3,000	625	Good	212	49
3,500	620	Good	224	52
4,000	590	Good	217	50
4,500	542	Good	197	42

According to the results of Table 3, when the powder powder is used, the slump flow increases, but the dispersibility of the fiber tends to worsen, and the compressive strength and the flexural strength tend to decrease. This may be due to the decrease in viscosity and the filling effect on the boundary between cement composites and sand and steel fibers.

Characteristics of Steel Fiber Reinforced Concrete Fusions According to the Content of Cement Contents (by Cement Weight)

Stone mixing rate (by weight of cement)	Slump Flow (mm)	Fiber dispersibility	Compressive strength (MPa)	Flexural strength (MPa)
0	608	Bad	152	35
5	613	usually	191	42
10	615	Good	199	45
20	615	Good	208	52
25	616	Good	224	49
30	592	usually	203	44
35	527	usually	187	37
40	471	Bad	165	31

Based on the results in Table 4, the powder content of the stone powder was selected as 3,500 and the mixing test results of the stone powder in the cement weight part 100 were 0, 5, 10, 20, 25, 30, 35, 40. It was. The rest of the test conditions were carried out under the same conditions as in Example 1. As shown in Table 5, when no powder was used, there was a serious problem in dispersibility, such as agglomeration of fibers, and low compressive strength and flexural strength.

In addition, when the mixing ratio of stone powder is more than 30%, the dispersibility of the fiber was reduced, and both compressive strength and flexural strength were reduced. Therefore, the amount of stone powder is preferably used in the range of 10 to 25%.

Example 3

This example was carried out to analyze the effect of the shape of the steel fiber on the properties of the fiber-reinforced concrete composite, based on the test results of Examples 1 and 2, Zirconium-containing silica-based silica powder and meta to 100 parts by weight of cement It contains 25 parts by weight of a mixture of kaolin 2: 1, powdered fine powder having a powder degree of 2,000 to 4,500 cm2 / g, containing 20 parts by weight of filler, and having a particle size of 5 mm or less compared to 100 parts by weight of cement. Based on the mortar further comprising 110 parts by weight of sand, a test was performed to compare the conventional straight steel fibers with steel fibers in the form of a coil spring. The remaining test conditions were tested under the same conditions as in Example 1 and Example 2.

Characteristics of Fiber Reinforced Concrete Fusion with Different Fiber Types

Type of fiber			Slope pulley (mm)	Dispersibility of the Fiber	Compressive strength (MPa)	Flexural strength (MPa)	Flexural Toughness (MPa)
Conventional fiber	Tensile Strength 3,000MPa, Diameter 0.2mm, Length 13mm		625	Good	204	42	10.1
Fiber of the present invention (inner diameter 0.25mm, pitch 2.8mm use)	Fiber diameter (tensile strength 3,000 MPa, length 13 mm)	0.15	630	Good	197	58	20.5
		0.2	620	Good	210	66	22.1
		0.3	610	Good	208	62	19.7
		0.4	580	Good	201	52	16.2
	Fiber length (tensile strength 3,000 MPa, diameter 0.2 mm)	10	615	Good	207	62	20.2
		13	620	Good	210	66	22.1
		20	610	Good	207	61	20.4
		30	600	Good	205	58	18.3

The diameter of steel fiber showed the highest value in compressive strength, flexural strength and flexural toughness at 0.2mm, and the fiber length showed the highest compressive strength, flexural strength and flexural toughness at 13mm and ranged in diameter from 0.2 to 0.5mm. 10 ~ 15mm, twisted 3 to 6 times spiral (coil spring form), using a steel fiber characterized in that the tensile strength of 2,500 ~ 3,000Mpa 150% improvement in bending strength compared to the conventional straight steel fiber, bending The toughness can be improved by more than 200%. Hereinafter, the steel fibers used in the fiber reinforced concrete composite will be described in more detail.

1 to 5 are views for explaining the steel fiber of the coil spring form. Hereinafter, the description of the above-described parts may be omitted.

Referring to Figure 1, the steel fiber 10 according to the present invention may have a coil spring twisted spirally.

Steel fibers may be preferably copper (Cu) coating to improve the bonding strength (adhesion) with the cement.

Such steel fibers, as shown in FIG. 2, may be combined with cement particles 21, fine powder particles 22, sand particles 23, and zirconium silicate fine particles 24 in a concrete composite to improve physical properties. .

Figure 2 conceptually represents the side cross-section of the steel fiber 10 included in the fiber reinforced concrete composite.

Figure 3 conceptually represents a cross section cut in the width direction of the steel fiber 10 included in the fiber reinforced concrete composite.

Referring to FIG. 3, cement particles 21, fine powder powder particles 22, sand particles 23, and zirconium silica fine powder particles 24 may be disposed inside the coil spring-shaped steel fiber 10.

Accordingly, the physical properties of the concrete composite can be further improved as compared with the conventional one using a straight steel fiber.

Thus, in order to locate the cement particles 21, fine powder powder particles 22, sand particles 23, zirconium silica fine powder particles 24 inside the coil spring-shaped steel fiber 10, It may be desirable for the inner diameter to be larger than the diameter of the sand particles 23.

4 (A) is a straight steel fiber 100 according to the first comparative example, Figure 4 (B) is a steel fiber 10 in the form of a spirally coiled coil spring according to the present invention.

Looking at Figure 4 (B), the pitch (Pitch, D1) of the steel fiber 10 according to the invention may be larger than the inner diameter (W1).

In the case of Figure 4 (B), while it is possible to reduce the consumption of resources required to manufacture the steel fiber 10, it may be possible to improve the physical properties of the concrete composite.

On the other hand, in the case of Figure 4 (A) can reduce the resource consumption, but it may be difficult to improve the physical properties (compressive strength, etc.) of the concrete composite.

In addition, as shown in FIG. 4B, the inner diameter W1 of the steel fiber 10 according to the present invention may be larger than the thickness T1. In this case, the sand particles 23 and the like can be effectively positioned inside the steel fiber 10.

5 (A) is a steel fiber 110 according to the second comparative example, Figure 5 (B) is a steel fiber 10 according to the present invention.

Although the steel fiber 110 according to the second comparative example of FIG. 5A has a coil spring shape, the pitch D2 is smaller than the inner diameter W2.

5A and 5B, in the case of FIG. 5A, sand particles 23 and the like penetrate into the steel fiber 110 from the side of the coil spring-shaped steel fiber 110. Can be difficult.

In addition, in the case of Figure 5 (A), the production cost may be excessively high because the use of a high amount of resources in order to manufacture the steel fiber 110 long enough.

On the other hand, the steel fiber 10 according to the present invention as shown in FIG. Can be prevented.

The steel fiber 10 according to the present invention may also have a plate shape rather than a coil spring shape. This will be described below with reference to the accompanying drawings.

6 to 9 are views for explaining the steel fiber in the form of a plate. Hereinafter, the description of the above-described parts may be omitted.

Referring to Figure 6, the steel fiber 10 according to the present invention may have a plate shape having a predetermined thickness (Y), width (X) and length (L).

Steel plate 10 in the form of a plate is also possible to improve the physical properties in the fiber reinforced concrete composite.

Steel fiber 10 according to the present invention, in order to improve the bonding force in the concrete composite, it is possible to have a twisted form, as shown in Figure 7 to 8 (A).

The steel fiber 10 may be twisted in a direction at least partially perpendicular to the longitudinal direction.

In other words, the steel fiber 10 has a first portion (First Portion, MA1) and the second portion (Second Portion, MA2) and the first portion (MA1) and the second having a plate shape as shown in FIG. It may include a torsion port (TA) located between the portions MA2.

The warpage portion TA may be generated by twisting the plate-shaped steel fiber 10 by a predetermined angle.

Accordingly, the cross section of the first portion MA1 and the cross section of the second portion MA may cross each other.

The case where the cross section of 1st part MA1 and the cross section of 2nd part MA cross | intersect is shown to FIG. 8 (B) and (C).

8 (C) can be seen that the steel fiber 10 is twisted twice. This can be fully interpreted through FIG. 9.

As such, when the plate-shaped steel fiber 10 has a twisted shape, the surface area is increased by the twisting portion TA, thereby improving the bonding force in the concrete composite.

In addition, when the steel fiber 10 has a shape that is twisted, the direction in which each portion of the steel fiber 10 can be changed to improve the bonding strength in the concrete composite.

For example, in the case of FIG. 8A, the direction toward which the wide surface of the first portion MA1 faces and the direction toward which the wide surface of the second portion MA2 faces is approximately 90 degrees (°). Can fly

Under the condition that the warpage portion TA in the steel fiber 10 functions to stagger the first portion MA1 and the second portion MA2, the length of the warpage portion TA may be relatively shorter than that of the other portions. none.

In detail, the length S1 of the warpage portion TA may be shorter than the length S2 of the first portion MA1 and the length S3 of the second portion MA2.

As shown in Figure 9, the steel fiber 10 according to the present invention may include a plurality of twists (TA1, TA2).

Preferably, the number of the twist portion TA included in the steel fiber 10 may be 3 to 6 pieces.

In this case, the steel fiber 10 can further improve the bonding force in the concrete composite.

As described above, the present specification and drawings have been described with respect to preferred embodiments of the present invention, although specific terms are used, it is only used in a general sense to easily explain the technical contents of the present invention and to help the understanding of the present invention. It is not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

Claims (7)

1. In fiber reinforced concrete composite,

   cement;

   20 to 30 admixture mixed with fine zirconium-containing silica powder having a specific surface area of 85,000 to 120,000 cm2 / g and metakaolin having a specific surface area of 10,000 to 20,000 cm2 / g in a ratio of 2: 1 to 3: 1 relative to 100 parts by weight of the cement. Parts by weight;

   100 to 130 parts by weight of sand relative to 100 parts by weight of cement;

   10 to 25 parts by weight of stone powder having a powder degree of 3,000 to 4,000 cm 2 / g relative to the cement 100 weight ratio; And

   Steel fibers;

   Including,

   The steel fiber is 2 to 5% of the total volume, copper (Cu) coating, 0.2 to 0.5mm in diameter, 10 to 15mm in length, tensile strength is 2,500 ~ 3,000Mpa, coil spring Spring) fiber reinforced concrete composite, characterized in that the type.
2. The method of claim 1,

   The steel fiber is

   Fiber reinforced concrete composite with a pitch greater than the inner diameter.
3. The method of claim 2,

   The steel fiber is

   Fiber reinforced concrete composite having an inner diameter greater than the thickness.
4. The method of claim 2,

   The steel fiber is

   Fiber reinforced concrete composite having an inner diameter larger than the diameter of the sand.
5. In fiber reinforced concrete composite,

   cement;

   20 to 30 admixture mixed with fine zirconium-containing silica powder having a specific surface area of 85,000 to 120,000 cm2 / g and metakaolin having a specific surface area of 10,000 to 20,000 cm2 / g in a ratio of 2: 1 to 3: 1 relative to 100 parts by weight of the cement. Parts by weight;

   100 to 130 parts by weight of sand relative to 100 parts by weight of cement;

   10 to 25 parts by weight of stone powder having a powder degree of 3,000 to 4,000 cm 2 / g relative to the cement 100 weight ratio; And

   Steel fibers;

   Including,

   The steel fiber is

   First Portion having a plate shape;

   A second portion having a plate shape and having a cross section crossing the cross section of the first portion; And

   A torsion part disposed between the first part and the second part and having a twisted shape;

   Fiber-reinforced concrete composite, comprising a.
6. The method of claim 5, wherein

   The length of the twist portion is fiber reinforced concrete composite shorter than the length of the first portion and the length of the second portion.
7. The method of claim 5, wherein

   The steel fiber is a copper (Cu) coating,

   Fiber reinforced concrete composite with 2 to 5% of total volume, copper (Cu) coating, and tensile strength 2,500 to 3,000 Mpa.

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