KR20110051914A - Manufacturing methods of ultra-high performance fiber reinforecd concrete mixing the steel fiber of wave and straight type - Google Patents

Abstract

PURPOSE: A method for manufacturing a steel-fiber-reinforced cement composite is provided to improve the ductile behavior and the mechanical adhesive of the composite based on wave type steel fiber and straight type steel fiber. CONSTITUTION: Mortar is obtained by mixing sand, reactive powder, a filling material, thickening agent with the cement. The mortar is mixed with mixing water in which 90 to 99.5 weight% of water and 0.5 to 10 weight% of a water reducing agent. 1 to 5vol% of straight type steel fiber and wave type steel fiber are added, based on 100vol% of the concrete. The mortar mixture is cured for 1 to 3 days under a wet condition and is cured for 2 to 4 days under a vapor condition.

Description

MANUFACTURING METHODS OF ULTRA-HIGH PERFORMANCE FIBER REINFORECD CONCRETE MIXING THE STEEL FIBER OF WAVE AND STRAIGHT TYPE}

The present invention relates to a method of manufacturing a super high-performance steel fiber reinforced cement composite, and more particularly, by mixing the corrugated steel fiber and straight steel fiber mechanically to improve the adhesion performance of the steel fiber and cement composite and to improve the ductile behavior and It relates to a manufacturing method of ultra-high performance steel fiber reinforced cement composite using the same.

Concrete is widely used in the construction of concrete structures together with steel as an economical and durable construction material. However, concrete has an inherent bond with low tensile strength and flexural strength, and is easily cracked, and brittle failure of concrete has been a problem due to an increase in compressive strength due to the practical use of high strength concrete.

Meanwhile, in order to prevent brittle fracture of concrete, fiber reinforced concrete (Fiber Reinforced Concrete) manufactured by mixing steel fiber to 1% (75kg / ㎥) or less in the volume of general concrete is added to some concrete structures. It is used.

Such steel fibers are mostly made of straight steel fibers having a circular cross section and hook-type steel fibers having bent ends.

In general, the steel fibers are those having a tensile strength of 1,500 MPa or less, lengths of about 10 mm to 30 mm, and diameters of about 0.45 mm to 1.0 mm.

However, 1% of steel fiber incorporation does not sufficiently prevent brittle fracture of high-strength concrete, and thus, the structure is immediately destroyed when an earthquake or repetitive and impact load of a vehicle, fire, and natural degradation occur.

In addition, in the case of using a straight steel fiber having a conventional circular cross-section in ultra-high strength concrete that is more than 180MPa conventionally (Patent No. 10-0620866; steel fiber reinforced cement composite and its manufacturing method) concrete is broken due to lack of tensile strength of steel fiber There is a problem that before the fiber reaches the yield strength does not help to improve the bending or tensile strength.

1A and 1B, even when steel fibers having a tensile strength of 2,000 MPa or more are used, when only straight steel fibers having a circular cross section are used, the steel fibers reach the yield strength at the time of bending or tensile failure before the steel fibers reach the breaking strength and are broken. There is a problem that the steel fiber reinforcing effect is dropped due to the phenomenon of debonding, which does not significantly contribute to the improvement of toughness.

In addition, as shown in FIG. 1C, the maximum bending strength is increased in the case of using only the corrugated steel fiber, but the cement matrix part is peeled off after the maximum bending strength, and thus it is more resistant than the frictional steel fiber. There was a problem in that a sharp fractured shape appeared.

In order to overcome the problems of conventional concrete, steel fiber reinforced concrete and super high strength steel fiber reinforced concrete mentioned above, research and experiments have been conducted. When mixed with straight steel fibers and wavy steel fibers,

Corrugated steel fiber can improve the adhesion performance with the matrix before the maximum bending strength to improve the maximum bending strength to secure excellent tensile strength,

The straight steel fiber has been proposed in the present invention that it is possible to secure excellent ductility behavior by preventing the breakage of the cement matrix portion after the maximum bending strength, which is a disadvantage of the wavy steel fiber, and sudden breakage.

An object of the present invention is to provide a method for producing an ultra-high-performance steel fiber reinforced cement composite in which corrugated steel fibers and linear steel fibers are mixed by mixing the corrugated steel fibers with the straight steel fibers.

In order to achieve the above object, the steel fiber of the present invention is incorporated into a cement composite (concrete) to increase the tensile strength of the composite, wherein the shape of the steel fiber is wavy (wave type) and straight (linear, Straight Type).

In addition, the concrete manufacturing method of the present invention for achieving the above object is to mix 1 ~ 5vol% of the corrugated steel fiber and straight steel fiber with respect to 100vol% cement composite, but the total mixing ratio of the wavy steel fiber and straight steel fiber is 5% It is characterized by producing an ultra-high performance steel fiber reinforced cement composite within a range not exceeding.

The present invention uses a corrugated steel fiber to improve the mechanical adhesion performance of the hardened steel fiber reinforced cement composite, and the use of a straight steel fiber to secure the excellent ductile behavior, the corrugated steel fiber wave number, length and depth In addition, the range of tensile strength and straight steel fiber were presented in detail through experiments on the diameter, length, and shape ratio, and the mechanical properties such as bending strength and tensile strength of the ultra-high performance steel fiber reinforced cement composites were finally improved.

That is, by improving the adhesion performance with the cement composite it is possible to greatly improve the mechanical performance, such as bending strength and tensile strength of 180MPa or more compressive strength.

Hereinafter, the present invention will be described more specifically.

The steel fibers used in the ultra-high performance steel fiber reinforced cement composite according to the present invention are characterized by mixing straight and wavy shapes.

At this time, the straight steel fiber is a circular cross section as shown in Figure 2 extending in the longitudinal direction means a steel fiber having a constant diameter and length,

The corrugated steel fiber refers to corrugated steel fiber (wave fiber formed with a wave) such as to form a straight steel fiber in the longitudinal direction as shown in FIG.

In particular, the wave shape of the corrugated steel fiber can be modified in various ways depending on the number, length and depth of the steel fiber, the tensile strength, etc. Among them, the present invention suggests a more optimal form through the experiment as follows .

As described above, the steel fibers (linear steel fibers and wavy steel fibers) used in the present invention may be manufactured by cutting, casting, etc., thinly cutting carbon steel, and the aspect ratio (length ratio to the cross-sectional dimension) is 30 to 100 or so may be used, but may be appropriately changed and used depending on the purpose and purpose, and the length thereof may also be manufactured by various lengths.

Preferably, the steel fiber is preferably 0.15 to 0.35 mm in diameter, and 10 to 30 mm in length, for the purpose of optimizing the ease of wave work of the steel fiber and adhesion to the hardened cement body.

When the steel fibers having such diameters and lengths are used in the straight form or when the straight steel fibers are manufactured in the wave form, the tensile strength of the steel fibers can be determined to be 2,000 to 4,000 MPa. It becomes possible to exercise enough.

As can be seen in Figure 2, the wavy steel fiber of the present invention has a geometrical shape, such as the water-like form compared to the straight circular fiber of the conventional circular cross-section, mechanical adhesion is increased to improve the adhesion performance of the steel fiber and cement hardened material The performance of high performance steel fiber reinforced cement composites can be improved.

In other words, the technical features of improving the adhesion performance with the hardened steel fiber reinforced cement hardening by introducing the shape of the steel fiber without changing the length, diameter and shape ratio of the steel fiber only.

These corrugated steel fibers have different effects on the performance of ultra-high performance steel fiber reinforced cement composites according to the number, depth (wave height) and length of wave formation (wave or wave).

Therefore, the corrugated steel fiber is determined by appropriately determining the number, depth and length of the wave according to the formulation and materials used for the ultra-high performance steel fiber reinforced cement composite.

Preferably, the corrugated steel fiber according to the present invention is a wave in a straight steel fiber having a diameter of 0.15 ~ 0.35mm, and a length of 10 ~ 30mm in Figure 2 in consideration of mechanical adhesion performance, filling rate of the steel fiber, fracture properties of the steel fiber, etc. It is preferable that they are 4-8 pieces, wave depth (w) 0.12-0.35 mm, and wave length ((lambda)) 1.86-3.82 mm.

The manufacturing method of the wavy steel fiber as described above, unlike the circular fiber that takes the process of drawing-cutting work for the steel fiber wire, it takes the process of drawing-shaped-cutting.

Here, the fresh work refers to the process of drawing into a steel fiber having a diameter of the required to produce a steel fiber,

Shaping refers to the operation of making steel fibers such that the fresh steel fiber circle goes into the wave form to the required number of waves, depth and length.

At the end of this operation, the steel sheet is cut to a certain size to produce wavy steel fibers.

The manufactured corrugated steel fibers can be manufactured in a single type and bundle type, which can improve the dispersibility of fibers and the ease of putting them into concrete, as shown in FIG. 3.

Straight and wavy steel fibers as described above, when included in the ultra-high performance steel fiber reinforced cement composite, 1 to 5vol% based on 100vol% cement composite.

If the content of the straight and wavy steel fiber is less than 1vol% with respect to the cement composite, the compounding effect is insignificant, and if it exceeds 5vol%, the strength is rather lowered due to agglomeration of fibers.

Looking at an example of manufacturing a steel fiber reinforced cement composite using the steel fibers described above (Patent No. 10-0620866; by steel fiber reinforced cement composite and its manufacturing method) cement, reactive powder, sand, filler, thickener, water reducing agent And steel fiber reinforced cement composites composed of steel fibers.

That is, for example, a premixing mortar material, which is a mixture of cement, sand, reactive powder, filler and thickener, is mixed with a high-speed mixer after mixing water with a high-performance water reducing agent. Steel fibers of different sizes are added to the mixture alone or in a hybrid form, mixed again, and then manufactured through a curing period of a certain period.

Specifically, the premixing mortar material is to place a storage site for the material constituting the construction site, to reduce the cost and minimize the weighing error and to reduce the mixing time.

For example, 100 to 130 parts by weight of sand based on 100 parts by weight of cement, 10 to 30 parts by weight of reactive powder, 10 to 30 parts by weight of filler and 0.05 to 1 parts by weight of thickener. Prepared by mixing evenly for ˜15 minutes.

In order to secure the fluidity and workability of the premixed mortar material thus prepared, water (typically distilled water is preferred) and a polycarboxylic high performance water reducing agent or a naphthalene high performance water reducing agent having a solid content of 30 to 40% by weight The blended water was prepared to form a ratio of 90 to 99.5% by weight and 0.5 to 10% by weight, respectively, and the premixed mortar and the blended water were mixed in a high speed mixer so that the ratio of the compounded water-binder (sum of cement and reactive powder) was 0.25 or less. Mix for 7-15 minutes at 20-40 rpm.

Into the mixture of the mortar and the blended water, the steel fibers alone or steel fibers having various diameters and lengths in a hybrid form in 1 to 5% by volume to the mixture for 3 to 10 minutes at a speed of 30 to 50rpm Mix.

At this time, in the present invention, the steel fiber is mixed with the straight steel fiber and the wavy steel fiber of circular cross section.

Then, after the final mixture was subjected to wet curing for 1 to 3 days, steam curing was performed at a high temperature of 60 to 110 ^° C. to activate the hydration reaction of cement and the Pozzolanic reaction of reactive powder. Steel fiber reinforced concrete is produced by performing for four days.

The sand is quartz sand (90 wt% or more of SiO ₂ ) having a size of 5 mm or less, and about 100 to 130 parts by weight is used based on 100 parts by weight of cement. The reason for using sand of 5mm or less is to secure the homogeneity of the cement composite and improve its strength.

The reactive powder is a mineral admixture such as silica fume, blast furnace slag, fly ash and the like. Such reactive powder is used in about 10 to 30 parts by weight based on 100 parts by weight of cement.

Since the reactive powder is composed of spherical particles, the workability is improved by reducing friction of the steel fiber reinforced cement composite (steel fiber reinforced concrete), the fiber dispersibility is increased by increasing the viscosity of the paste, and the strength by the pozzolanic reaction It serves to improve.

Generally, the reactive powder is reacted with calcium hydroxide (Ca (OH) ₂ ), which is a hydration product of cement, to form a calcium silicate salt (3CaO2SiO ₂ 3H ₂ O) and calcium aluminate salt (3CaOAl ₂ O ₃ ) by a pozzolan reaction. Although there is an advantage of increasing the long-term strength, the use of cement decreases as early as the age of reactive powder, the initial strength of the concrete is lowered, the construction period is long, there is a disadvantage that a lot of shrinkage occurs.

In order to solve such problems as the initial strength decrease due to the reactive powder, steam curing is carried out at a high temperature of 60 to 120 ^o C at the early stage of age so that the hydration reaction of the cement and the pozzolanic reaction of the reactive powder are activated.

By such a technical configuration, not only the hydration reaction of cement proceeds quickly, but calcium hydroxide is almost consumed by the pozzolanic reaction, thereby overcoming the initial drop in strength of the steel fiber reinforced cement composite, and at the same time, it is possible to realize super strength.

The filler is 10 to 30 parts by weight of quartz powder (SiO ₂ 95% or more) or limestone fine powder (CaCO ₃ or more 75% or more) based on 100 parts by weight of cement.

The use of such a filler prevents destruction of the interface region by a filler action filled in the interface region between the cement paste and the aggregate or the interface region between the cement paste and the fiber, thereby improving the strength of the steel fiber reinforced cement composite.

The thickener is used to impart viscosity to the cement matrix. Cellulose thickener or acryl thickener is used in an amount of 0.05 to 1 parts by weight based on 100 parts by weight of cement. Such thickeners serve to improve fiber dispersibility of steel fiber reinforced cement composites.

Reducing agents are used to ensure the fluidity of the cement matrix. In the steel fiber reinforced cement composite, 0.5 to 10 parts by weight of a polycarboxylic acid-based high performance water reducing agent or a naphthalene-based high performance water reducing agent having a solid content of 30 to 40% by weight based on 100 parts by weight of cement is used. Such a water reducing agent serves to improve the workability and fiber dispersibility of the steel fiber reinforced cement composite.

In general, in the steel fiber-reinforced cement composites, the fiber ball phenomenon occurs when a large amount of steel fiber is used because the specific gravity and aspect ratio of the steel fiber are different from the particles of the material constituting the cement matrix. It is known to occur and fail to achieve the original performance of the steel fiber reinforced cement composite or to cause brittle fracture and deterioration of durability.

However, the steel fiber-reinforced cement composite can secure high fiber dispersibility by using the above-described thickener and water reducing agent, so that a high toughness can be realized by adding a large amount of steel fibers to the steel fiber-reinforced cement composite without fiber aggregation as described below.

Hereinafter, the present invention will be described in more detail with reference to Examples.

≪ Example 1 >

This embodiment is to analyze the effect on the performance of the steel fiber reinforced cement composite incorporating wavy and straight steel fibers according to the present invention, the slump flow, fiber of the steel fiber reinforced cement composite when the wavy and straight steel fibers are used, respectively Dispersibility, compressive strength and flexural strength test were carried out.

At this time, the concrete of the used specimen was prepared by selecting a formulation that can secure more than 180MPa compressive strength.

That is, the blending used is 100 to 130 parts by weight of sand having a particle size of 5 mm or less based on 100 parts by weight of cement, 10 to 30 parts by weight of reactive powder such as silica fume, 10 to 30 parts by weight of filler, and fiber agglomeration. Preparing a mortar comprising 0.05 to 1 parts by weight of a thickener for reducing, and the binder of the mortar (cement) for the formulation number 1 consisting of 90% to 99.5% by weight of water and 0.5% to 10% by weight of a high performance water reducing agent In the mixing of the blended water and the mortar so that the ratio of

Silica fume (SiO ₂ 96%, density 2.10 g / cm 3, specific surface area 200,000 cm ₂ / g) is 30 parts by weight based on 100 parts by weight of cement, and sand (density 2.62 g / cm 3, average particle diameter of 0.5 mm or less) is 100 weight of cement 110 parts by weight based on parts, 30 parts by weight of filler (SiO ₂ 99.3, average particle diameter 10㎛ or less) was used based on 100 parts by weight of cement, polycarboxylic acid-based high-performance reducing agent (35% solid component) is cement 100 1.8 parts by weight based on parts by weight was used.

 However, straight steel fibers were 0.2mm in diameter × 13mm in length and 2,800 MPa in tensile strength. Corrugated steel fibers were 0.2mm × 13mm in length and 2,800MPa in tensile strength. The number of waves is 6, the depth of wave is 0.24mm, the length of wave Was 1.86 mm. In addition, the mixing ratio of steel fibers was set at 1 to 5% with respect to 100vol% of the cement composite.

In the mixing operation, the cement, silica fume, sand and fillers constituting the cement composite are added to a mixer and mixed at a speed of 30 rpm for about 10 minutes, and then mixed with water and a high performance water reducer for 10 minutes at a speed of 100 rpm, and then mixed again. Mixing is carried out for 5 minutes at a speed of 40 rpm.

In addition, the curing operation was performed after the specimens were wet cured for 2 days, and then steam cured at 90 ^° C. for 2 days, and then exposed to air in the air until 28 days, and then tested.

The compressive strength of the cement composite thus produced showed an ultra high strength of about 198 MPa.

The slump flow is classified as KS F 2594, fiber dispersion, good, normal, and poor by visual observation as shown in FIG. 4, and the results are shown in Table 1 below.

Compressive strength and flexural strength were measured according to KS F 2405 and KS F 2566 at predetermined ages as shown in FIG. 5, and the results are shown in Table 1 below.

Fibrous
Mixing rate Mixing rate
(Vol.%) Slump Flow
(mm) Fibrous
Dispersibility Compressive strength
(MPa) Flexural strength
(MPa) Equivalent bending strength
(MPa)

Wavy
Steel fiber
One 627 Good 189 26.4 8.4 2 620 Good 201 38.1 9.8 3 575 Bad 194 31.0 14.1 4 540 Bad 191 - - 5 521 Bad 184 - -

Straight
Steel fiber
One 625 Good 188 26.1 8.7 2 620 Good 199 34.5 10.2 3 618 Good 204 39.8 15.1 4 614 Good 206 41.2 18.4 5 601 Good 209 44.5 20.5

As can be seen in Table 1, when the slump flow is used in the corrugated steel fiber as shown in Figures 6a and 6b, the slump flow was found to be 600 or more at a mixing rate of 1 to 2%, and at the mixing rate of 3% or more, The dispersibility of the fibers was found to be poor.

The reason for this is that the steel fibers have a wavy shape rather than a straight shape, and thus, when a large amount of steel fibers are used, the fibers are entangled with each other.

When linear steel fiber is used, the slump flow is more than 600mm at 1 ~ 5%, and the general slump flow of high flow concrete that does not need compaction when constructing steel fiber reinforced cement composite (concrete) is over 600mm, and the dispersibility of fiber is mostly good. Appeared.

However, the compressive strength shows an enhancement effect as the amount of steel fiber is increased, but does not show a significant difference like the flexural strength.

In the case of the large bending strength, when the corrugated steel fiber is used, the mixing ratio is increased up to 2%, but at 3% or more, the maximum bending strength decreases due to poor dispersion of the steel fiber.

6C and 6D, when the amount of steel fiber is mixed, the flexural strength is gradually improved when the linear steel fiber is used. Accordingly, the maximum flexural strength is higher than that of the straight steel fiber.

The reason is that the corrugated steel fiber exhibits a great bridging effect due to the improved adhesion performance of the hardened cement body.

However, the equivalent flexural strength, which is the average flexural strength at a given displacement (l / 150), was higher for the straight steel fiber than for the corrugated steel fiber. The reason for this is that the flexural behavior after the maximum flexural strength is caused by the rapid breakdown of steel fiber reinforced cement composites using corrugated steel fibers.

Thus, even though the bridging effect of the fiber is increased due to the improved adhesion between the corrugated steel fiber and the hardened cement composite of the cement fiber, the tensile strength of the steel fiber is large. This is because it is unable to resist friction.

<Example 2>

This embodiment is to analyze the effect on the performance of the steel fiber reinforced cement composite incorporating wavy and straight steel fibers according to the present invention, the slump flow of the steel fiber reinforced cement composite when mixed with wavy and straight steel fibers, Dispersibility, compressive strength, and flexural strength tests of the fibers were performed.

Steel fiber reinforced cement composites used are the same as in Example 1 Patent No. 10-0620866; Among the formulations presented in the steel fiber reinforced cement composite and its manufacturing method, the formulations were selected to ensure a compressive strength of 180 MPa or more, and the materials and curing procedures used were the same.

However, straight steel fibers were 0.2mm in diameter × 13mm in length and 2,800 MPa in tensile strength. Corrugated steel fibers were 0.2mm × 13mm in length and 2,800MPa in tensile strength. The number of waves is 6, the depth of wave is 0.24mm, the length of wave Was 1.86 mm. In addition, the mixing ratio of steel fibers was 1.5 to 2% in the wave shape and the straight shape.

The slump flow is classified as good, normal, or poor by KS F 2594, fiber dispersion, and visual evaluation as shown in FIGS. 7A, 7B, 8A, and 8B, and the results are shown in Table 2 below.

Compressive strength and flexural strength were measured according to KS F 2405 and KS F 2566 at predetermined ages, and the results are shown in Table 2 below.

Incorporation rate (%)
Slump Flow
(mm)
Fibrous
Dispersibility
Compressive strength
(MPa) maximum
Flexural strength
(MPa) equivalence
Flexural strength
(MPa) Wavy Straight

1.5%
1.5 - 622 Good 192.2 31.4 9.1 1.0 0.5 618 Good 193.5 35.4 10.7 0.5 1.0 620 Good 190.8 34.1 10.4 - 1.5 625 Good 192.2 29.4 9.5

2%
2.0 - 617 Good 197.4 38.5 9.8 1.5 0.5 620 Good 201.4 41.5 11.8 1.0 1.0 617 Good 200.0 40.7 12.6 0.5 1.5 614 Good 204.8 40.1 13.1 - 2.0 619 Good 197.9 34.5 10.2

As can be seen in Table 2, the slump flow was found to be 600 or more in both slump flow and the use of mixed and straight steel fibers alone, even in the 1.5 ~ 2%, it is determined that there is no problem in workability do.

In addition, the dispersibility of the fibers was also good, indicating that there is no problem as a high-flow concrete that does not require compaction when constructing an ultra-high performance steel fiber reinforced cement composite.

In addition, the compressive strength showed an enhancement effect as the amount of fiber was increased, but did not show a significant difference like the flexural strength, and even when the wavy and straight steel fibers were mixed, there was no significant difference in the compressive strength.

In the case of the maximum bending strength, the maximum bending strength increased as the fiber mixing rate increased, and the maximum bending strength was improved in the same mixing rate when mixed with the wavy and straight steel fibers alone.

In addition, it was found that the equivalent bending strength was enhanced when the steel fiber was used in the mixture rather than when used alone.

That is, in the case of corrugated fiber, the maximum flexural strength is high, but the cement matrix part thereafter has peeled off, and it has a disadvantage in that it fails to be resistant to friction adhesion after the maximum flexural strength, and in the case of straight steel fibers, after the maximum flexural strength While the ductile behavior is good, the maximum bending strength is lower than that of the corrugated steel fiber. However, when the wavy and straight steel fibers are mixed and used, the weaknesses of the respective steel fibers are compensated for. Therefore, the mixed and the straight steel fibers are considered to be more enhanced than the single and maximum flexural strengths.

For this reason, the dynamic performance of ultra-high performance steel fiber reinforced cement composites using 2% of conventional straight steel fibers is similar to the case of mixing 0.5% and 1% of corrugated and straight steel fibers, respectively. In case of using steel fiber, it is possible to develop ultra-high performance steel fiber reinforced cement composite with excellent mechanical performance.

Figure 1a is a real picture of the drawing conditions of the steel fiber during bending failure of ultra-high performance fiber reinforced concrete,

Figure 1b is a longitudinal cross-sectional view of a straight steel fiber of a circular cross section conventionally used,

Figure 1c is a longitudinal cross-sectional view of the wavy steel fibers used in the present invention,

Figure 2 is a schematic diagram using the straight and wavy steel fibers used in the present invention,

3 is an actual picture of the wavy steel fibers used in the present invention,

Figure 4 is a slump flow test picture in the steel fiber reinforced concrete according to the present invention,

Figure 5 is a comparison picture and contrast of the compressive strength maximum bending strength and equivalent bending strength in the corrugated steel fiber ultra-high performance concrete according to the present invention,

Figure 6a is a graph showing the slump flow and compressive strength according to the mixing ratio of the steel fiber reinforced concrete incorporating wave steel fibers according to the present invention.

Figure 6b is a graph showing the maximum bending strength and equivalent bending strength according to the mixing ratio of the steel fiber reinforced concrete incorporating wave steel fibers according to the present invention.

Figure 6c is a graph showing the slump flow and compressive strength according to the mixing ratio of the steel fiber reinforced concrete incorporating the straight steel fiber according to the present invention.

Figure 6d is a graph showing the maximum bending strength and equivalent bending strength according to the mixing ratio of the ultra-high performance concrete incorporating the straight steel fiber according to the present invention.

Figure 7a is a graph showing the slump flow and compressive strength of ultra-high-performance concrete mixed with a steel fiber mixed with a wave and straight line according to the present invention with a volume ratio of 1.5%.

Figure 7b is a graph showing the maximum bending strength and equivalent bending strength of the super high-performance concrete mixed with a steel fiber mixed with a wave and straight line according to the present invention with a volume ratio of 1.5%.

Figure 8a is a graph showing the slump flow and compressive strength of ultra-high performance concrete mixed with a steel fiber mixed with a wave and straight line according to the present invention by a volume ratio of 2.0%.

Figure 8b is a graph showing the maximum bending strength and equivalent bending strength of the ultra-high performance concrete incorporating a steel fiber mixed with a wave and straight line according to the present invention by a volume ratio of 2.0%.

Claims (6)

In the manufacturing method of ultra-high performance steel fiber reinforced cement composite, The steel fiber is a method of manufacturing a super high-performance steel fiber reinforced cement composite incorporating a wavy steel fiber and a straight steel fiber, characterized in that 1 to 5vol% of the straight steel fiber and the corrugated steel fiber of a circular cross section with respect to 100vol% of concrete. The method of claim 1, Said straight steel fiber and wavy steel fiber has a diameter of 0.15 ~ 0.35mm, the method of producing a super high-performance steel fiber reinforced cement composite incorporating a wavy steel fiber and a straight steel fiber, characterized in that using a steel fiber having a length of 10 ~ 30mm. 3. The method of claim 2, The corrugated steel fiber is a straight steel fiber having a diameter of 0.15 ~ 0.35mm, a length of 10 ~ 30mm 4 ~ 8 wave number, the wave depth (w) 0.12 ~ 0.35mm, the wave length (λ) 1.86 ~ 3.82mm A method for producing an ultra-high performance steel fiber reinforced cement composite incorporating wavy steel fibers and straight steel fibers. 3. The method of claim 2, The steel fibers are a method of producing a super high-performance steel fiber reinforced cement composite incorporating wavy steel fibers and straight steel fibers, characterized in that the tensile strength is 2000 ~ 4000MPa. The method according to any one of claims 1 to 4, The steel fiber reinforced cement composite is Preparing a mortar including 100 to 130 parts by weight of sand, 10 to 30 parts by weight of reactive powder, 10 to 30 parts by weight of filler, and 0.05 to 1 part by weight of a thickener based on 100 parts by weight of cement; Mixing the blended water and mortar so that the ratio of the blending water consisting of 90% by weight to 99.5% by weight of water and 0.5% to 10% by weight of a reducing agent and the binder of the mortar (sum of cement and reactive powder) is 0.2 or less. step; A steel fiber input step of mixing the straight steel fibers and the wavy steel fibers in a mixture of the blended water and the mortar, by adding 1-5% by volume of the concrete; After the wet curing for 1 to 3 days for the blended water and the mortar mixture into which the steel fiber is added, performing steam curing for 2 to 4 days at a temperature of 60 ℃ to 110 ℃; Method for producing a super high-performance steel fiber reinforced cement composite containing a wave steel fiber and a straight steel fiber. The method of claim 5, wherein the mortar manufacturing step Mixing the mixture constituting the mortar for 7 minutes to 15 minutes at a speed of 20 rpm to 40 rpm; The mixing step of the blended water and mortar includes mixing for 7 minutes to 20 minutes at a speed of 80rpm to 120rpm and then mixing for 2 to 5 minutes at a speed of 40rpm to 60rpm; Mixing the steel fiber in the blended water and mortar is mixed for 3 to 10 minutes at a speed of 30rpm to 50rpm; Ultra-high performance steel fiber reinforced cement mixed with a wavy steel fiber and a straight steel fiber, characterized in that it comprises a Method for preparing a composite.

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