KR101705242B1 - Ultra-high performance fiber-reinforced concrete for improving construct ability, and manufacturing method for the same - Google Patents

Abstract

It is possible to improve the workability and quality of the ultra-high performance fiber-reinforced concrete because it does not retard the finishing time and delay the finishing time in most of the setting of the ultra high performance fiber reinforced concrete by using the organic retardant and the inorganic retarder appropriately in the ultra high performance fiber reinforced concrete. Also, by increasing the sharpening time by a factor of two, the slump flow can be secured up to 550 mm even if the sharpening time of 1 hour and 30 minutes has elapsed. There is no delay in hardening time and no reduction in strength, Reinforced concrete having improved workability and capable of securing a quick-setting time of a minute mold release time and a start timing of vapor curing and securing a compressive strength of 150 MPa or more and a flexural strength of 30 MPa or more, A manufacturing method is provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber reinforced concrete (FIBER), a fiber reinforced concrete (FIBER), a fiber reinforced concrete (FIBER)

The present invention relates to an ultra-high performance fiber reinforced concrete, and more particularly, to a method for improving the workability of an ultra high performance fiber-reinforced concrete by appropriately mixing a retarder to delay the initial setting time Reinforced concrete reinforced concrete.

With the development of construction technology, structures are gradually becoming higher, larger, and specialized. In recent years, interest in high-rise buildings and long bridges has been rising. As a result, concrete has evolved into ultra high strength and ultra high performance areas in order to reduce the weight of the concrete structure or to reduce the member cross section in the high strength concrete field to further secure the effective space.

In general, ultra-high-strength concrete or ultra-high-performance concrete means concrete with a compressive strength of 80 MPa or more, and is applied to skyscraper buildings and bridge bridges due to various advantages such as long-term conversation of structure span, reduction of vertical member section, improvement of durability, Is expected to increase.

In order to increase the compressive strength of such ultra high strength concrete or ultra high performance concrete, it is necessary to increase the amount of unit cement, which is the amount of binder composed of cement or cement and mineral admixture, And a fine aggregate composed of a certain amount of fine aggregate (S / a) and a coarse aggregate are mixed and manufactured using a mixer, which is a comparable device. At this time, since these materials do not rub against each other at a low water-binding ratio (W / B), a high performance water reducing agent is used to secure the fluidity required for concrete pouring at the time of construction. Such a high- have.

At this time, the required fluidity of the ultra-high-strength concrete or ultra-high-performance concrete has high fluidity and clear permeability so that the reinforcing bars and the like can be densely packed in the formwork without compaction or compaction, And the required homogeneity is ensured.

Here, the high-flowable concrete is also referred to as a self-filled high-flowable concrete and means a concrete having a very high flowability. The concrete having a slump flow higher than that of a slump flow of about 600 mm is referred to as a high- This technology is combined with ultra-high-strength concrete or ultra-high-performance concrete is manufactured.

In order to improve not only the compressive strength but also the fluidity and the durability, the ultra high strength concrete or the ultra high performance concrete is suitably selected as the mineral admixture such as the silica fume, the blast furnace slag, the fly ash and the limestone fine powder, The amount of unit cement is determined by composing the binder. The method and the manufacturing method of the binder are very important for ultra high strength concrete or ultra high performance concrete.

For example, the method of constructing ultrahigh-strength concrete or ultra-high-performance concrete is to mix minerals such as silica fume, blast furnace slag, fly ash, and limestone fine powder into cement with a binary or a mixture of two mineral materials And a ternary system in which a mixture of tungsten and tungsten is mixed with cement at a certain ratio.

This method is based on the pozzolanic reaction that slowly reacts with calcium hydroxide and mineral admixture caused by hydration of cement to form insoluble compounds. Concrete using these materials has advantages such as increased workability, bleeding reduction, long-term strength development, Is generally known to have.

 In addition, methods such as blast furnace slag fine powder, fly ash, and limestone fine powder are further pulverized to increase their powder degree to increase the pozzolanic reactivity.

However, when cement alone is used as a binder for ultrahigh strength concrete or ultra high performance concrete, the compressive strength is almost expressed at 28 days of age, and when the cement and mineral admixture are used together, And it is known that the projected compressive strength appears after about 90 days.

Therefore, depending on the kind of the admixture used, the timing of the manifestation of the strength differs. When two or more mineral admixtures are used together, the problem of the strength development may become more serious depending on the characteristics of the mineral admixture used.

In addition, when a mineral admixture is used, since the phenomenon that the strength is enhanced is based on the pozzolanic reaction to the long-term age, it is necessary to pay more attention to concrete curing.

On the other hand, as a conventional technology relating to ultrahigh strength concrete or ultra high performance concrete, there has been proposed a method in which cement is added with silica fume, blast furnace Slag fine powder and anhydrous gypsum in a suitable ratio, and a low water-binder ratio. In Korean Registered Patent No. 10-622048, there has been disclosed a composite composition for metakaolin Has been disclosed in Korean Patent No. 10-873514, and a binder for ultrahigh strength concrete using silica sand as a filler has been disclosed in Korean Registered Patent No. 10-873514.

The conventional technology related to ultrahigh strength concrete or ultra high performance concrete is a method of increasing the level of compressive strength by using excellent pozzolanic reaction material such as silica fume. However, pozzolanic reaction materials such as silica fume have a limitation in increasing the amount of materials such as silica fume because they cause a decrease in the fluidity of the concrete.

Specifically, ultrahigh strength concrete or ultra high performance concrete is characterized by using a large amount of binder of fine powder and a very low water-binding ratio of 0.3 or less. As a result, the viscosity of the concrete is increased, and the fluidity of the concrete is decreased, resulting in a problem that the workability is lowered. In order to solve such a problem of deterioration in workability of concrete, a high-performance water reducing agent can be used in a large amount to ensure workability, but the manufacturing cost is increased rapidly. In addition, recently, high-performance water reducing agent technology has been rapidly developed, and thus, the production of ultrahigh strength concrete or ultra high performance concrete has been simplified. However, a large amount of high performance water reducing agent has problems such as not only an increase in manufacturing cost but also a delay in congealing.

In recent years, development and related researches on Ultra-High Performance Concrete (UHPC), which improves the performance of ordinary concrete, which is a traditional construction material, have been actively pursued as the size and frequency of natural disasters have increased along with urbanization It is progressing.

This ultra high performance concrete (UHPC) has a compressive strength of 150 MPa or more and is defined as a concrete with a high binder content while using special aggregate so that the brittle behavior does not appear through the incorporation of fiber.

In addition, since the steel fiber reinforced concrete formed by mixing steel fiber into concrete is superior in resistance against toughness, ductility and impact compared to ordinary concrete, for example, Can be improved. In addition, steel fiber mixing can reduce the brittle fracture characteristics of concrete and improve ductility. Since these steel fiber reinforced concrete are relatively brittle compared to normal strength concrete, steel fiber reinforcement for high strength concrete is advantageous to reduce brittle fracture characteristics and also provides the advantage of reducing reinforcement in dense areas. In recent years, the performance of steel fiber reinforced concrete has been increased to such an extent that it is referred to as an ultra high-performance concrete having a compressive strength of 150 MPa or more through the development of ultrahigh strength and increase in toughness

On the other hand, the ultra high performance fiber reinforced concrete is a concrete with a compressive strength of 150 MPa or more and a flexural strength of 30 MPa or more. It has excellent durability such as saltiness, freezing and thawing and excellent fluidity. to be.

In order to exhibit this performance, the ultra high performance fiber reinforced concrete uses a large amount of fine powdery binder such as blast furnace slag or fly ash, has a very low water-binding ratio (W / B) of 0.2 or less, Fiber) and high-performance water reducing agents.

However, such an ultra high performance fiber reinforced concrete has a problem that the surface hardens rapidly in a short time due to the rapid drying of the surface because the amount of the compounding water is very small. This phenomenon is a cause of deterioration of workability and workability, which is an obstacle to manufacturing a large-sized structure.

In addition, when the surface of the ultra-high performance fiber-reinforced concrete is dried quickly, the bubbles generated in the concrete can not escape to the outside, resulting in a weakened concrete surface or poor installation.

In order to eliminate these problems, it is necessary to cover the concrete with vinyl or the like to prevent drying of the surface immediately after casting or spraying a product capable of blocking moisture evaporation. However, And delay of the construction period.

On the other hand, in order to prevent surface drying in such ultra high performance fiber reinforced concrete, there is a method of increasing the compounding number and a method of using a retarding agent.

For example, when the compounding number is increased, workability can be ensured, but the quality may be deteriorated due to the decrease in strength and the increase in shrinkage. In addition, if the retarding agent is not properly used, the coagulation / curing is delayed, and the strength is greatly lowered, resulting in problems such as air delay.

As described above, the phenomenon of surface drying in the ultra high performance fiber reinforced concrete has a considerable influence on the workability and quality, but there is no technique to prevent such phenomenon from the material aspect.

Korean Patent No. 10-686350 filed on November 28, 2005, entitled "Ultra High Strength Concrete Composition" Korean Patent No. 10-698759 filed on August 24, 2006, entitled "Cement Binder Composition for Ultrahigh Strength Concrete and Method for Manufacturing the Same" Korean Patent No. 10-873514 filed on Sep. 3, 2007, entitled "Binder for Ultrahigh Strength Concrete and Method of Making Concrete Using the Same" Korean Patent No. 10-927377 filed on June 9, 2008, entitled "Method for producing high performance concrete"

The present invention has been made to solve the above problems and an object of the present invention is to provide an ultra high performance fiber reinforced concrete in which the organic retarder and the inorganic retarder are appropriately mixed with each other and used in the setting of the ultra high performance fiber reinforced concrete, The present invention is to provide a method of manufacturing an ultrafine fiber reinforced concrete having improved workability and capable of improving workability and quality without delaying setting and delaying the final setting time.

Another technical problem to be solved by the present invention is to provide a cement mortar composition capable of securing a quick release time and preventing delay in the die removal timing and the steam curing initiation period and improving the workability to secure a compressive strength of 150 MPa or more and a flexural strength of 30 MPa or more Reinforced concrete having a high strength and a high strength.

As a means for achieving the above technical object, an ultra high performance fiber reinforced concrete having improved workability according to the present invention is formed by mixing cement, silica fume, blast furnace slag fine powder and fly ash, and the cement is mixed with 100 parts by weight , 6 to 20 parts by weight of silica fume, 22 to 35 parts by weight of blast furnace slag fine powder and 22 to 35 parts by weight of fly ash; 1 to 5 parts by weight of a steel fiber mixed with the binder based on 100 parts by weight of the cement; 65 to 85 parts by weight of coarse aggregate based on 100 parts by weight of cement; 45 to 55 parts by weight of fine aggregate based on 100 parts by weight of cement; 25 to 38 parts by weight of water (W) based on 100 parts by weight of cement so that the ratio of water-binder (W / B) is 0.2 or less; And 4 to 7 parts by weight of a high-performance water reducing agent based on 100 parts by weight of cement, wherein 0.2 to 0.8% by weight of a retarding agent of the compounding water is added in the mixing water, and the retarding agent 170 is delayed 20 to 40% by weight of sodium gluconate as an organic retarder and 60 to 80% by weight of borax as an inorganic retarder are mixed in the total retarder so as to maintain the termination time; And the fine aggregate ratio (S / a) given as the volume ratio of the fine aggregate to the total aggregate (fine aggregate + coarse aggregate) volume is smaller than 0.4 (40%).

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The steel fiber is a brass-coated straight fiber having a diameter of 0.2 mm or more and a length of 20 to 30 mm.

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Here, the high performance water reducing agent uses a polycarboxylic acid system, and the amount of the high performance water reducing agent can be adjusted according to the fluidity.

The silica fume of the binder is composed of spherical particles to improve rheology characteristics of the cement paste by reducing friction, to suppress voiding between the cement particles to improve the strength, And the strength and water tightness are improved by a pozzolanic reaction that reacts with calcium hydroxide generated at hydration.

Wherein the binder has a fly ash of 2,000 to 4,000 cm 2 / g, the blast furnace slag of the binder has a blast of 3,000 to 5,000 cm 2 / g, the fly ash and blast furnace slag have a blend ratio of 90:10 to 30 : 70% by weight, and the glass coating of the fly ash is broken at a temperature of 5 to 90 캜 by the hydration reaction and the polymerization reaction of the blast furnace slag.

As another means for achieving the above technical object, there is provided a method of manufacturing an ultra high performance fiber reinforced concrete having improved workability according to the present invention, comprising the steps of: a) cementing 100 parts by weight of cement in correspondence with a unit quantity of ultra high performance fiber- Preparing 25 to 38 parts by weight of water (W) in the formulated water; b) preparing a binder (B) in which 6 to 20 parts by weight of silica fume, 22 to 35 parts by weight of blast furnace slag powder and 22 to 35 parts by weight of fly ash are mixed with 100 parts by weight of cement; c) mixing 1 to 5 parts by weight of the steel fiber with the binder in an amount of 100 parts by weight of the cement; d) the ratio of the water-binding material (W / B) is less than or equal to 0.2; e) blending 4 to 7 parts by weight of a high-performance water reducing agent with 100 parts by weight of the cement; f) adding a retarding agent which is a mixture of an organic retarding agent and an inorganic retarding agent to the compounding water so as to delay the pesting time and to maintain the pesting time; g) selecting 45 to 55 parts by weight of the fine aggregate and 65 to 85 parts by weight of the coarse aggregate with 100 parts by weight of the cement so that the fine aggregate ratio (S / a) is smaller than 0.4; And h) mixing the binder mixed with the steel fiber, the fine aggregate, the coarse aggregate, and the mixing water added with the high performance water reducing agent and the retarder to form an ultra high performance fiber reinforced concrete, wherein the retarder of the step f) Wherein the retarder is added with 20 to 40% by weight of organic retarder sodium gluconate and 60 to 60% by weight of the total retarder so as to maintain the termination time, Mixed with borax which is 80% by weight of an inorganic retarder; The fine aggregate ratio (S / a) given as the volume ratio of the fine aggregate to the total aggregate (fine aggregate + coarse aggregate) volume is smaller than 0.4 (40%) and determines the fluidity of the concrete and reduces the amount of the high- do.

According to the present invention, by appropriately mixing an organic retarder and an inorganic retarder in an ultra-high performance fiber-reinforced concrete, it is possible to delay the final settling time of the ultra-high performance fiber- Quality can be improved.

According to the present invention, it is possible to secure a slump flow up to 550 mm even when a crisp time of 1 hour and 30 minutes has elapsed by increasing the sharpening time to twice, and there is no delay in curing time and no reduction in strength.

According to the present invention, it is possible to easily secure a pavement time of 1 hour and 30 minutes, to prevent the die removing timing and the vapor curing start timing from being delayed, and to secure a compressive strength of 150 MPa or more and a flexural strength of 30 MPa or more.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the construction of an ultra-high performance fiber-reinforced concrete with improved workability according to an embodiment of the present invention.
2 is a view illustrating the composition ratio of an ultra high performance fiber-reinforced concrete having improved workability according to an embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing an ultra-high performance fiber reinforced concrete having improved workability according to an embodiment of the present invention.
4 is a graph showing the characteristics of a steel fiber in an ultra-high performance fiber-reinforced concrete having improved workability according to an embodiment of the present invention.
5 is a view illustrating mixing of ultrafine fiber reinforced concrete with improved workability according to an embodiment of the present invention.
FIGS. 6A and 6B are views showing the results of a clean-up time and an end-time test, respectively, of an ultra-high performance fiber-reinforced concrete having improved workability according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

[Ultra-high performance fiber-reinforced concrete with improved workability (100)]

FIG. 1 is a view showing the construction of an ultra high performance fiber reinforced concrete with improved workability according to an embodiment of the present invention. FIG. 2 is a view showing a composition ratio of an ultra high performance fiber reinforced concrete having improved workability according to an embodiment of the present invention FIG.

1 and 2, an ultra-high performance fiber-reinforced concrete 100 having improved workability according to an embodiment of the present invention includes a binder B 110, a fine aggregate 120, a coarse aggregate 130, W, 140, a high performance water reducing agent 150, a steel fiber 160, and a retardant 170. The binder 110 is composed of cement 111, silica fume 112, fine blast furnace slag 113, The ash 114 is mixed and formed.

2, in an ultra-high performance fiber-reinforced concrete 100 having improved workability according to an embodiment of the present invention, a binder 110 is formed by mixing cement 111 and fly ash 114 , And 22 to 35 parts by weight of fly ash (114) is mixed with 100 parts by weight of the cement (111). The binder material B 110 is formed by further mixing silica fume 112 and blast furnace slag powder 113 with the cement 111 and the fly ash 114. The cement 111 is mixed with 100 parts by weight A mixture of 6 to 20 parts by weight of silica fume 112, 22 to 35 parts by weight of blast furnace slag 113 and 22 to 35 parts by weight of fly ash 114 may be blended.

1 to 5 parts by weight of the steel fiber (160) is incorporated based on 100 parts by weight of the cement (111). At this time, the steel fiber 160 is preferably a brass-coated straight fiber having a diameter of 0.2 mm or more and a length of 20 mm to 30 mm.

 The coarse aggregate 130 is mixed with 65 to 85 parts by weight based on 100 parts by weight of the cement 111. The fine aggregate 120 is mixed with the fine aggregate 130 having a volume ratio of the fine aggregate 120 to the total aggregate (fine aggregate + coarse aggregate) 45 to 55 parts by weight based on 100 parts by weight of the cement (111) are mixed so that the ratio (S / a) is less than 0.4. At this time, the fine aggregate ratio (S / a) is preferably less than 0.4 (40%) to determine the flowability of the concrete and reduce the amount of the high-performance water reducing agent 150 used.

Water (W: 140) is blended, and 25 to 38 parts by weight of the 100 parts by weight of the cement (111) is incorporated so that the ratio (W / B) of the water-binding material is 0.2 or less.

4 to 7 parts by weight of the high-performance water reducer agent (150) is incorporated based on 100 parts by weight of the cement (111). For example, the high performance water reducing agent 150 uses a polycarboxylic acid system, and the amount of the high performance water reducing agent 150 can be adjusted according to fluidity. That is, the high-performance water reducing agent 150 is based on the use of a polycarboxylic acid-based system, and the amount to be used can be appropriately determined according to the water-binding ratio, the kind of the binder 110, Here, the water reducing agent is a kind of concrete mixer, which is a surface active agent that disperses each particle by charging cement particles while rubbing, and has an effect of increasing the effective hydration area, decreasing the yield, improving the workability, and improving the water resistance.

A retarder (170) is added to the compounding water (140) to mix the organic retarder and the inorganic retarder so as to delay the crisp time and maintain the termination time. At this time, 0.2 to 0.8% by weight of the retarder 170 is added to the compounding number. Also, the retarder 170 may be prepared by mixing 20 to 40% by weight of an organic retarder and 60 to 80% by weight of an inorganic retarder, wherein the organic retarder is sodium gluconate and the inorganic retarder is borax But are not limited to, Here, the retarder 170 of concrete is a kind of a mixed material, and is a material used for delaying the setting time of cement.

More specifically, although the cement 111 of the binder 110 can usually use Portland cement, crude steel portland cement, mixed cement, etc., it is preferable to use Portland cement (OPC) usually in terms of economy.

The silica fume (112) of the binder (110) is formed of spherical particles, so that the rheology of the cement paste can be improved by reducing the friction, and the voids between the cement particles It is possible to suppress the filling and improve the strength. In addition, the silica fume 112 enhances strength and water tightness by a pozzolanic reaction that reacts with calcium hydroxide generated at hydration of the cement 111, so that the performance of the ultra high performance concrete 100 according to the embodiment of the present invention Can be improved. For example, the silica fume 112 may be used in an amount of about 6 to about 20 parts by weight based on 100 parts by weight of the cement (111) so as to satisfy KS F 2567 (Korean Industrial Standard for silica fume for concrete) desirable.

More specifically, the silica fume 112 is a very fine pozzolanic material produced as a by-product in the process of producing silicon metal or ferro silicon in an electric arc furnace, Silicon, and is also referred to as condensed silica fume or microsilica. Such silica fumes are classified into a powder form (undensified type or as-produced type) produced in the form recovered in the recovery process according to a material handling method, a granular form (condensed with a constant pressure) and a slurry Type). For example, the unit mass per unit product type of silica fume is 450 kg / m 3 or less for undensified type, 700 kg / m 3 or less for granular type, 1350 to 450 kg / m 3 for slurry type, .

In addition to the cement 111 and the silica fume 112, the binder 110 may have a fly ash 114 having a powdery degree of 2,000 to 4,000 cm 2 / g and a powdery degree of 3,000 to 5,000 cm 2 / g Wherein the mixing ratio of the fly ash (114) and the blast furnace slag (113) is 90: 10 to 30: 70% by weight, and the blast furnace slag (113) The glass coating of the fly ash 114 is broken at a temperature of 5 to 90 DEG C by the reaction and the polymerization reaction. For example, the mixing ratio of the fly ash 114 and the blast furnace slag 113 can be adjusted according to workability and initial strength. When the mixing ratio of the fly ash 114 and the blast furnace slag 113 is 50:50 , The ultra high performance fiber reinforced concrete can have a compressive strength of 150 MPa or more.

When the powdery degree of the fly ash (114) is less than 2,000 cm 2 / g and the blast furnace slag (113) has a powdery degree of less than 3,000 cm 2 / g, the reactivity is low, which is disadvantageous in terms of strength development. If the powdery degree of the blast furnace slag 113 exceeds 4,000 cm2 / g and the powdery degree of the blast furnace slag 113 exceeds 5,000 cm2 / g, the reactivity is large, but the powder generated in the thermal power plant or the steel mill becomes larger, Or classification, which may reduce economic efficiency.

The fly ash 114 and the blast furnace slag 113 may be blended at a weight ratio of, for example, 90:10 to 30:70 by weight. When the weight ratio of the fly ash 114 is 90 (The weight ratio of the blast furnace slag is less than 10%), the workability is secured. However, there is a problem in that the compressive strength is significantly lowered at room temperature curing, and when the weight ratio of the fly ash 114 is less than 30% (The weight ratio of the blast furnace slag is more than 70%), the compressive strength can be secured with high strength, but the workability is not ensured.

In order to prepare the ultra high performance fiber reinforced concrete of 150 MPa or more by adjusting the mixing ratio of the fly ash 114 and the blast furnace slag 113, the fly ash 114 and the blast furnace slag 113 113) at a ratio of about 1: 1 is most effective. That is, ultra high performance fiber-reinforced concrete capable of easily adjusting the fluidity and strength according to the user's demand according to the mixing ratio of the fly ash (114) and the blast furnace slag (113) can be manufactured.

Also, the glass material of the fly ash 114 is broken at the room temperature of 5 to 40 ° C by hydration reaction and polymerization reaction of the blast furnace slag 113. That is, when the fly ash (114) is used, a glassy coating is formed. Therefore, in order to accelerate the reaction of the fly ash (114) by breaking the glass coating, a very high alkali environment of pH 13 or higher, Other methods are needed. However, since the blast furnace slag 113 contains a large amount of SiO ₂ , Al ₂ O ₃ , particularly CaO (generally containing 40% or more of blast furnace slag), the hydration reaction and the polymerization reaction are carried out at room temperature, Even if a glass coat of the fly ash 114 is destroyed and a large amount of the fly ash 114 is mixed, a polymerization reaction occurs at room temperature and the strength can be largely expressed.

Accordingly, the ultra-high performance fiber-reinforced concrete (100) having improved workability according to the embodiment of the present invention can be obtained by appropriately mixing an organic retarder and an inorganic retarder with ultra-high performance fiber-reinforced concrete, It is possible to improve the workability and the quality by delaying only the initializing time and not delaying the finalizing time.

[Method for producing ultra-high performance fiber-reinforced concrete (100) having improved workability]

FIG. 3 is a flowchart illustrating an operation of the method for manufacturing an ultra-high performance fiber reinforced concrete according to an embodiment of the present invention. FIG. 4 is a graph showing the characteristics of a steel fiber in an ultra high performance fiber reinforced concrete having improved workability according to an embodiment of the present invention. Fig.

Referring to FIG. 3, a method for manufacturing an ultra-high performance fiber-reinforced concrete having improved workability according to an embodiment of the present invention includes: firstly, cement (111) is mixed with 100 parts by weight 25 to 38 parts by weight of water (W: 140) is prepared as a compounding water (S110).

Next, 100 parts by weight of cement (111) is mixed with 6 to 20 parts by weight of silica fume (112), 22 to 35 parts by weight of blast furnace slag fine powder (113) and 22 to 35 parts by weight of fly ash (B) 110 are prepared (S120). At this time, the mixture constituting the binder 110 is mixed at a speed of 20 rpm to 40 rpm for 5 minutes to 7 minutes.

Next, 1 to 5 parts by weight of the steel fiber 160 is mixed into the binder 110 with the cement 111 as 100 parts by weight (S130). At this time, as shown in FIG. 4, the steel fiber 160 is preferably a brass-coated straight fiber having a diameter of 0.2 mm or more and a length of 20 mm to 30 mm.

Next, the mixture is blended so that the ratio (W / B) of the water-binder is 0.2 or less (S140). At this time, the mixture is mixed for 4 minutes to 10 minutes at a speed of 80 rpm to 120 rpm, and then mixed for 1 minute to 3 minutes at a speed of 40 rpm to 60 rpm.

Next, 4 to 7 parts by weight of the high-performance water reducing agent 150 is blended with 100 parts by weight of the cement 111 (S150). At this time, the high performance water reducing agent 150 uses a polycarboxylic acid system, and the amount of the high performance water reducing agent 150 can be adjusted according to fluidity.

Next, a delay agent 170 mixed with an organic retarder and an inorganic retarder is added to the compounding water so as to delay the clean-up time and maintain the termination time (S160). At this time, 0.2 to 0.8% by weight of the retarder 170 is added to the compounding number. Also, the retarder 170 may be prepared by mixing 20 to 40% by weight of an organic retarder and 60 to 80% by weight of an inorganic retarder, wherein the organic retarder is sodium gluconate and the inorganic retarder is borax But are not limited to,

Next, 45 to 55 parts by weight of the fine aggregate 120 and 65 to 85 parts by weight of the coarse aggregate 130 are selected using 100 parts by weight of the cement 111 so that the fine aggregate ratio S / a is less than 0.4 ). At this time, the fine aggregate ratio S / a determines the flowability of the concrete as a volume ratio of the fine aggregate 120 to the total aggregate volume (fine aggregate + coarse aggregate) 40%).

Next, the binder 110 in which the steel fiber is mixed, the fine aggregate 120, the coarse aggregate 130, and the mixing water 140 added with the high performance water reducing agent 150 and the retarder 170 are mixed to form a super- The high performance fiber reinforced concrete 100 is formed (S180).

[Experimental Example]

FIG. 5 is a view illustrating blending of an ultra-high performance fiber-reinforced concrete having improved workability according to an embodiment of the present invention. FIGS. 6A and 6B are cross- These are the figures showing the results of the clean-up time and the termination time of concrete, respectively.

 The ultrafine fiber reinforced concrete 100 having improved workability according to an embodiment of the present invention is characterized in that it comprises a binder 110 110 in which cement 111, silica fume 112, blast furnace slag fine powder 113 and fly ash 114 are mixed The water 140 and the high-performance water reducing agent 150 are introduced into the mixer at a speed of 20 rpm to 40 rpm for 5 minutes to 7 minutes, To 120 rpm for 4 minutes to 10 minutes, and then mixed at a speed of 40 rpm to 60 rpm for 1 minute to 3 minutes to prepare ultrahigh strength concrete. Then, the compressive strength and the slump flow were measured respectively .

As shown in FIG. 5, Comparative Example 1 shows the case where no retarding agent is used, Comparative Example 2 shows the case of using a retarder composed of only sodium gluconate, and Comparative Example 3 shows that borax ) Is used. In Comparative Example 4, sodium gluconate was used in an amount of not more than 20% by weight and borax was used in an amount of not less than 80% by weight, and Comparative Example 5 was conducted in an amount of not less than 40% by weight of sodium gluconate And a case where borax is used in an amount of 60% by weight or less.

Specifically, in the ultra-high performance fiber-reinforced concrete 100 in which the workability is improved according to the embodiment of the present invention, the retarder 170 is composed of 20 to 40% by weight of the organic retarder as sodium gluconate and the inorganic retarder as borax, 60 to 80% by weight, preferably 0.2 to 0.8% by weight of the compounding water.

At this time, as shown in Comparative Example 2 in FIGS. 6A and 6B, when the retarder composed of only sodium gluconate was used, the termination time was significantly delayed compared to the cleanness time and the hardening and strength were lowered, There is a problem that the die removal timing and the steam curing start timing are delayed.

Also, as shown in Comparative Example 3 in Figs. 6A and 6B, when a retarder composed only of borax is used, the pre-fixation time is delayed too much, resulting in lowering of hardening and strength, Is delayed.

Therefore, in the ultra high performance fiber reinforced concrete having improved workability according to the embodiment of the present invention, when sodium gluconate and borax are properly mixed as the retarder 170, the finishing time is appropriately maintained and the finishing time is hardly affected Therefore, there is no deterioration of hardening and strength, and therefore, there is no problem at all at the die removing timing and steam curing start timing.

However, as shown in Comparative Example 4 in Figs. 6A and 6B, when the sodium gluconate was used in an amount of 20 wt% or less and borax was used in an amount of 80 wt% or more, both the crisping time and the termination time were delayed, In addition, as shown in Comparative Example 5 in Figs. 6A and 6B, when 40 wt% or more of sodium gluconate and 60 wt% or less of borax are used, both a crisp time and a termination time are promoted, thereby making it difficult to secure workability.

In addition, when the retarder 170 using sodium gluconate and borax mixed with 0.2% by weight or less of the compounding water 140 is used, the retarding effect with respect to the crisp time is significantly lowered, and the retardant is 0.8 When the weight% or more is used, the retarding effect according to the crisp time is considerably increased, and the hardening and the strength deterioration are large.

As a result, according to the embodiment of the present invention, it is possible to secure a slump flow up to 550 mm even when a crisp time of 1 hour and 30 minutes has elapsed by increasing the sharpening time by two times, And it is possible to easily secure a pavement time of 1 hour and 30 minutes, to prevent the die removing timing and the vapor curing start timing from being delayed, and to secure a compressive strength of 150 MPa or more and a flexural strength of 30 MPa or more.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: Ultra high performance fiber reinforced concrete
110: binder (Binder: B)
111: Cement
112: Silica Fume
113: Blast furnace slag fine powder (BS)
114: fly ash (FA)
120: Fine Aggregate
130: coarse aggregate
140: water (W) (mixing water)
150: High performance water reducing agent
160: Steel Fiber
170: retarder (mixture of organic retarder and inorganic retarder)

Claims (14)

The silica fume 112 is formed by mixing cement 111, silica fume 112, blast furnace slag fine powder 113 and fly ash 114 with 100 parts by weight of the cement 111, (B: 110) mixed with 22 to 35 parts by weight of blast furnace slag 113 and 22 to 35 parts by weight of fly ash 114;
1 to 5 parts by weight of a steel fiber (160) mixed into the binder (110) based on 100 parts by weight of the cement (111);
65 to 85 parts by weight of coarse aggregate (130) based on 100 parts by weight of cement (111);
45 to 55 parts by weight of fine aggregate (120) based on 100 parts by weight of cement (111);
(W: 140) of 25 to 38 parts by weight based on 100 parts by weight of the cement (111) so that the ratio (W / B) of the water-binder is not more than 0.2; And
4 to 7 parts by weight of the high-performance water reducing agent 150 based on 100 parts by weight of the cement (111)
, ≪ / RTI &
A retarder 170 of 0.2 to 0.8% by weight of the compounding number is added in the compounding water, and the retarder 170 is added in an amount of 20 to 40% by weight of the total retarder so as to maintain the termination time Sodium gluconate as an organic retarder and borax as an inorganic retarder of 60 to 80% by weight; And the fine aggregate ratio (S / a) given as the volume ratio of the fine aggregate (120) to the total aggregate (fine aggregate + coarse aggregate) volume is smaller than 0.4 (40%). delete delete The method according to claim 1,
The steel fiber (160) is a brass-coated straight fiber having a diameter of 0.2 mm or more and a length of 20 mm to 30 mm. delete The method according to claim 1,
Wherein the high performance water reducing agent (150) is a polycarbonate based resin and the amount of the high performance water reducing agent (150) is adjusted according to fluidity. The method according to claim 1,
The silica fume (112) of the binder (110) is composed of spherical particles to reduce the friction, thereby improving the rheology characteristic of the cement paste, filling the pores between the cement particles (111) Reinforced concrete having improved workability by improving strength and water tightness by a pozzolanic reaction which reacts with calcium hydroxide generated upon hydration of the cement (111). The method according to claim 1,
Wherein the fly ash 114 of the binder 110 has a degree of powder of 2,000 to 4,000 cm 2 / g and the blast furnace slag 113 of the binder 110 has a degree of powder of 3,000 to 5,000 cm 2 / g, The ash (114) and the blast furnace slag (113) are mixed at a mixing ratio of 90:10 to 30:70% by weight. The fly ash (113) is heated at a temperature of 5 to 90 ° C by hydration reaction and polymerization reaction of the blast furnace slag Reinforced concrete having improved workability, characterized in that the glass coating of the fiber reinforced concrete (114) is broken. a) preparing 25 to 38 parts by weight of water (W: 140) by mixing water with 100 parts by weight of cement (111) corresponding to the unit water amount of ultra high performance fiber reinforced concrete (100);
(b) A binder material comprising 100 parts by weight of cement (111) mixed with 6-20 parts by weight of silica fume (112), 22-35 parts by weight of blast furnace slag fine powder (113) and 22-35 parts by weight of fly ash B: 110);
c) mixing 1 to 5 parts by weight of the steel fiber (160) into the binder (110) with 100 parts by weight of the cement (111);
d) the ratio of the water-binding material (W / B) is less than or equal to 0.2;
e) combining 4 to 7 parts by weight of the high-performance water reducing agent (150) with 100 parts by weight of the cement (111);
f) adding a retarding agent (170) mixed with an organic retarding agent and an inorganic retarding agent to the compounding water so as to delay the panning time and maintain the panning time;
g) selecting 45 to 55 parts by weight of the fine aggregate 120 and 65 to 85 parts by weight of the coarse aggregate 130 with 100 parts by weight of the cement 111 so that the fine aggregate ratio S / a is less than 0.4; And
h) mixing the binder 110 in which the steel fiber is mixed, the fine aggregate 120, the coarse aggregate 130 and the blend water 140 added with the high performance water reducing agent 150 and the retardant 170, Step of forming fiber-reinforced concrete (100)
, ≪ / RTI &
The retarder 170 in the step f) is added in an amount of 0.2 to 0.8% by weight based on the compounding amount, and the retarder 170 is added in an amount of 20 to 40% by weight of the total retarder so as to maintain the termination time, By weight of sodium gluconate as an organic retarder and borax as an inorganic retarder of 60 to 80% by weight; The fine aggregate ratio (S / a) given as the volume ratio of the fine aggregate 120 to the total aggregate (fine aggregate + coarse aggregate) volume is smaller than 0.4 (40%) and determines the fluidity of the concrete and reduces the amount of the high- Wherein the fiber reinforced concrete is produced by a method comprising the steps of: delete delete 10. The method of claim 9,
Wherein the steel fiber (160) is a brass-coated straight fiber having a diameter of 0.2 mm or more and a length of 20 mm to 30 mm. 10. The method of claim 9,
Wherein the high performance water reducing agent 150 in step e) uses a polycarboxylic acid system and the amount of the high performance water reducing agent 150 is adjusted according to fluidity. delete

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