Apparatus and method for manufacturing high performance concrete capable of manufacturing high performance concrete through processes of inserting air into normal concrete and dissipating air

Abstract

Disclosed is an apparatus and method for manufacturing high-performance concrete by introducing air into normal concrete and dissipating air, wherein high-performance concrete is formed in a manner in which bubbles, which are to be removed, are added in a large amount together with an admixture to pre-blended normal concrete so that the admixture is uniformly dispersed in the normal concrete using the ball-bearing effect of the bubbles, thus forming mixed concrete, and the mixed concrete is discharged using air at a high pressure of 5 atom or more to thereby shoot high-performance concrete of which the slump, remarkably increased due to the large amount of bubbles, is reduced to fall within the range of slump of normal concrete while dissipating excess air from the mixed concrete.

Claims

1. An apparatus for manufacturing high-performance concrete by introducing air into normal concrete and dissipating air, comprising: a normal concrete formation unit for forming normal concrete by blending water, cement, and aggregate at a predetermined ratio; a bubble and admixture feeding unit for feeding bubbles and an admixture to the normal concrete to increase a slump of the normal concrete; a mixed concrete formation unit, comprising a shaft that is rotated by power of a motor in an agitator truck containing the normal concrete, and a mixing member having one or more blades radially provided to the shaft to mix the normal concrete with the bubbles and the admixture, fed from the bubble and admixture feeding unit, thus forming mixed concrete; and a high-performance concrete shooting unit for shooting high-performance concrete of which a slump, increased due to the bubbles, is reduced to fall within a range of slump of normal concrete while dissipating the bubbles from the mixed concrete by discharging the mixed concrete using air at a high pressure of 5 atm or more.

2. The apparatus of claim 1, wherein the bubble and admixture feeding unit is operated to feed a foamed slurry resulting from mixing the bubbles and a slurry.

3. The apparatus of claim 2, wherein the slurry is produced by blending the admixture with water.

4. The apparatus of claim 1, wherein the bubble and admixture feeding unit is operated to sequentially feed the bubbles and a slurry to the normal concrete.

5. The apparatus of claim 4, wherein the slurry is produced by blending the admixture with water.

6. The apparatus of claim 1, wherein the bubble and admixture feeding unit is operated to sequentially feed the bubbles and the admixture to the normal concrete.

7. The apparatus of claim 6, wherein the admixture comprises any one or more selected from among silica fume, metakaolin, flyash, blast slag powder, latex, and a polymer.

8. The apparatus of claim 7, wherein the silica fume is used in an amount of 5 to 15 parts by weight based on 100 parts by weight of cement for normal concrete.

9. The apparatus of claim 7, wherein the metakaolin is used in an amount of 7 to 20 parts by weight based on 100 parts by weight of cement for normal concrete.

10. The apparatus of claim 7, wherein the flyash and the blast slag powder are used in amounts of 15 to 25 parts by weight based on 100 parts by weight of cement for normal concrete.

11. The apparatus of claim 7, wherein the latex and the polymer are used in amounts of 3 to 15 parts by weight based on 100 parts by weight of cement for normal concrete.

12. The apparatus of claim 1, wherein the bubbles are generated using a foaming agent and a bubble generator.

13. The apparatus of claim 12, wherein the mixed concrete is added with an antifoaming agent so as to eliminate excess air introduced by the foaming agent and the bubble generator.

14. The apparatus of claim 1, wherein the bubbles are generated using a blowing agent.

15. The apparatus of claim 14, wherein the mixed concrete is added with an antifoaming agent so as to eliminate excess air introduced by the blowing agent.

16. The apparatus of claim 1, wherein the high-performance concrete shooting unit comprises: a shooting guide member removably attached to the mixed concrete formation unit and configured such that a center thereof has a smaller diameter than both ends thereof, which communicate with each other, so that the mixed concrete is discharged in a compressed state; and an air supply path formed through the shooting guide member to supply air at a high pressure of 5 atm or more so as to reduce an amount of air while dissipating the bubbles from the mixed concrete that is moved to the shooting guide member.

17. The apparatus of claim 16, wherein the air supply path is radially inclinedly formed at an outer surface of the shooting guide member.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a flowchart illustrating the process according to the present invention;

(2) FIG. 2 is a schematic view illustrating the apparatus according to the present invention;

(3) FIG. 3 illustrates the normal concrete formation unit according to the present invention;

(4) FIG. 4 illustrates the production of slurry according to the present invention;

(5) FIG. 5 illustrates the production of foamed slurry according to the present invention;

(6) FIG. 6 is an enlarged image illustrating the foamed slurry produced in FIG. 5;

(7) FIGS. 7 and 8 illustrate the mixed concrete formation unit according to an embodiment of the present invention;

(8) FIG. 9 illustrates the mixed concrete according to another embodiment of the present invention;

(9) FIGS. 10 and 11 are images illustrating the slumps of normal concrete and mixed concrete according to the present invention;

(10) FIGS. 12 and 13 illustrate the shooting of the high-performance concrete using the high-performance concrete shooting unit according to the present invention;

(11) FIG. 14 is a top plan view illustrating the high-performance concrete shooting unit according to the present invention;

(12) FIG. 15 is an image illustrating the slump of the high-performance concrete according to the present invention; and

(13) FIG. 16 is a graph illustrating the air content in the high-performance concrete after shooting using the high-performance concrete shooting unit according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS IN THE DRAWINGS

(14) 100: apparatus for manufacturing high-performance concrete 110: normal concrete formation unit 120: bubble and admixture feeding unit 130: mixed concrete formation unit 140: high-performance concrete shooting unit

MODE FOR INVENTION

(15) Hereinafter, a detailed description will be given of the present invention with the appended drawings. FIG. 1 is a flowchart illustrating the process according to the present invention, and FIG. 2 is a schematic view illustrating the apparatus according to the present invention.

(16) According to the present invention, the apparatus 100 for manufacturing high-performance concrete by introducing air into normal concrete and dissipating air comprises: a normal concrete formation unit 110 for forming normal concrete by blending water, cement and aggregate at a predetermined ratio, a bubble and admixture feeding unit 120 for feeding bubbles and an admixture to the normal concrete to increase the slump of the normal concrete, a mixed concrete formation unit 130 including a shaft 131 that is rotated by the power of a motor in an agitator truck containing the normal concrete and a mixing member 132 having one or more blades radially provided to the shaft 131 so that the normal concrete is mixed with the bubbles and the admixture, fed from the bubble and admixture feeding unit 120, to form mixed concrete, and a high-performance concrete shooting unit 140 for shooting high-performance concrete of which the slump, which is increased due to the bubbles, is reduced to fall within the range of slump of normal concrete while dissipating the bubbles from the mixed concrete by discharging the mixed concrete using air at a high pressure of 5 atm or more.

(17) Also, the apparatus 100 for manufacturing high-performance concrete by introducing air into normal concrete and dissipating air according to the present invention comprises: a normal concrete formation unit 110 for forming normal concrete by blending water, cement and aggregate at a predetermined ratio, a bubble and admixture feeding unit 120 for feeding bubbles and an admixture to the normal concrete to increase the slump of the normal concrete, a mixed concrete formation unit 130 including a hopper 133 that receives the normal concrete, the bubbles and the admixture and a mixing member 135 for mixing the bubbles and the admixture, fed from the bubble and admixture feeding unit 120, together with the normal concrete, which are fed into the hopper 133, by the rotation of a screw 134 to form mixed concrete, and a high-performance concrete shooting unit 140 for shooting high-performance concrete of which the slump, which is increased due to the bubbles, is reduced to fall within the range of slump of normal concrete while dissipating the bubbles from the mixed concrete by discharging the mixed concrete using air at a high pressure of 5 atm or more.

(18) The bubble and admixture feeding unit 120 is preferably operated to feed foamed slurry, resulting from mixing the bubbles and slurry.

(19) The bubble and admixture feeding unit 120 is operated to sequentially feed the bubbles and slurry to the normal concrete.

(20) The slurry is preferably prepared by blending the admixture with water.

(21) The bubble and admixture feeding unit 120 is operated to sequentially feed the bubbles and the admixture to the normal concrete.

(22) The admixture preferably comprises any one or more selected from among silica fume, metakaolin, flyash, blast slag powder, latex, and a polymer.

(23) The silica fume is used in an amount of 5 to 15 parts by weight based on 100 parts by weight of the cement for normal concrete.

(24) The metakaolin is used in an amount of 7 to 20 parts by weight based on 100 parts by weight of the cement for normal concrete.

(25) The flyash and the blast slag powder are used in amounts of 15 to 25 parts by weight based on 100 parts by weight of the cement for normal concrete.

(26) The latex and the polymer are used in amounts of 3 to 15 parts by weight based on 100 parts by weight of the cement for normal concrete.

(27) The bubbles are generated using a foaming agent and a bubble generator or a blowing agent, and are introduced in an amount of 20 to 40% based on 100% of the normal concrete.

(28) The admixture is uniformly dispersed in the normal concrete by virtue of the large amount of bubbles, thus forming mixed concrete, and an antifoaming agent is added to the mixed concrete to eliminate excess bubbles from the normal concrete so as to realize high-performance concrete having a desired slump and strength.

(29) The high-performance concrete shooting unit 140 includes a shooting guide member 141, which is removably attached to the mixed concrete formation unit 130 and is configured such that the center thereof has a smaller diameter than both ends, which communicate with each other, so as to discharge the mixed concrete in a compressed state, and an air supply path 142 formed through the shooting guide member to supply air at a high pressure of 5 atm or more so as to reduce the air content while dissipating the bubbles from the mixed concrete that is moved to the shooting guide member 141.

(30) The air supply path 142 is radially inclinedly formed at the outer surface of the shooting guide member.

(31) Below is a description of the manufacturing process according to the present invention.

(32) As illustrated in FIG. 3, water, cement and aggregate, which are fed from a batching plant (BP), are blended and mixed at a predetermined ratio, thus forming normal concrete having a slump of 60 mm or more, which is then transported to the construction site using an agitator truck 111.

(33) Normal concrete having a slump of 40 mm or less, obtained by blending and mixing water, cement and aggregate, which are fed from a batching plant (BP), at a predetermined ratio, is transported to the construction site using a dump truck.

(34) As illustrated in FIGS. 4 and 5, the admixture such as silica fume, metakaolin, flyash, latex, or polymer, fed from the bubble and admixture feeding unit 120, is blended with water at a ratio of 1:1 using a mixer such as a screw to thus produce a slurry, which is then mixed with bubbles generated using a foaming agent and a bubble generator, by means of a mixer such as a screw, thus obtaining a foamed slurry, after which the foamed slurry is added to normal concrete. The foamed slurry is preferably obtained by blending 1 kg of the admixture with 8 to 10 L of the bubbles, the exact ratio being appropriately determined in consideration of the desired slump and strength of the high-performance concrete.

(35) The foaming agent is used to separately add bubbles to pre-blended normal concrete, and functions to physically feed bubbles through a surface-active action by being diluted with water in an amount corresponding to 30 to 50 times the amount thereof, thereby obtaining air content up to about 80%. In the present invention, the effective amount of the bubbles is preferably set so that the air content is 20 to 40% based on the total amount of high-performance concrete, and the bubbles have a shape close to a spherical shape and a size of 0.01 to 0.3 mm, smaller bubbles being preferable.

(36) The bubbles may be generated using a blowing agent. In the course of addition of normal concrete with a blowing agent, stirring and re-mixing, bubbles are generated. The bubbles are initially formed to have a large size due to the high-speed rotation of the mixer, and the size thereof is decreased during the stirring, thus obtaining a comparatively uniform bubble size distribution, but the amount of bubbles that are generated may vary depending on the mixing time. The blowing agent may include an aluminum powder, and is preferably used in an amount of 0.1 to 0.5% based on the total amount of high-performance concrete.

(37) An enlarged image of the foamed slurry including bubbles and silica fume is illustrated in FIG. 6. The bubbles A contained in the foamed slurry have a size of about 0.1 to 1 mm, and the foamed slurry is configured such that the admixture including silica fume S is uniformly distributed between the bubbles.

(38) The addition of the foamed slurry comprising the slurry and the bubbles to normal concrete is as described above, but the bubbles and the slurry may be sequentially added to the normal concrete.

(39) Alternatively, instead of preparing the slurry, the normal concrete may be sequentially added with bubbles and an admixture, for example, any one or more selected from among silica fume, metakaolin, flyash, slag powder, latex, and a polymer. The silica fume is used in an amount of 5 to 15 parts by weight based on 100 parts by weight of cement for normal concrete, the metakaolin is used in an amount of 7 to 20 parts by weight based on 100 parts by weight of cement for normal concrete, the flyash and the blast slag powder are used in amounts of 15 to 25 parts by weight based on 100 parts by weight of cement for normal concrete, and the latex and the polymer are used in amounts of 3 to 15 parts by weight based on 100 parts by weight of cement for normal concrete. If the amount of the corresponding component is less than the lower limit, strength and durability may be decreased. On the other hand, if the amount thereof exceeds the upper limit, strength and durability are not further increased and construction costs may increase.

(40) The foamed slurry or the bubbles and the admixture, fed from the bubble and admixture feeding unit 120, are mixed with the normal concrete in the mixed concrete formation unit 130. The mixing ratio of the normal concrete and the foamed slurry is as follows. The foamed slurry is used in an amount of 300 to 400 L relative to 1 m.sup.3 of the normal concrete, whereby the bubbles are contained in an amount of 30 to 35% in the mixed concrete.

(41) As illustrated in FIGS. 7 and 8, the mixed concrete formation unit 130 is operated in a manner in which the shaft 131 is rotated by the power of a motor (not shown) in the agitator truck 111, and simultaneously the mixing member 132, having one or more blades radially provided to the shaft 131, is rotated, whereby the normal concrete and the foamed slurry or the bubbles and the admixture or the blowing agent and the admixture are mixed, thus forming mixed concrete in which the admixture is efficiently dispersed in normal concrete using the ball-bearing effect of the bubbles.

(42) As illustrated in FIG. 9, the normal concrete having a slump of 40 mm or less is transported by a dump truck and then fed into the hopper 133 of the mixed concrete formation unit 130, the normal concrete fed into the hopper 133 is transferred to the mixing member 135 through the rotation of the screw 134, and the normal concrete transferred to the mixing member 135 is added with the bubbles and the admixture, fed from the bubble and admixture feeding unit 120, and then mixed together through the rotation of the screw 134.

(43) Although the bubbles and the admixture may be separately added, the mixing time of the bubbles, the admixture and the normal concrete through the rotation of the screw 134 is short, and thus, the addition of the foamed slurry to normal concrete is preferable.

(44) The mixed concrete formation unit 130 is an up-down stirring mixer, and is inclinedly formed so that the inlet is positioned lower than the outlet, whereby the foamed slurry and the normal concrete may be easily mixed due to the height difference of the mixing member 135.

(45) When the weight ratio of the admixture, such as silica fume, metakaolin, blast slag powder, latex or polymer, with the water, which together constitute the slurry, is set to 1:1, 1.5 kg of the admixture such as silica fume is mixed with 1.5 kg of water, thus producing a slurry. The ratio of the water and the admixture such as silica fume is determined in consideration of the slump and strength of the final high-performance concrete.

(46) FIG. 10 illustrates the slump of normal concrete. The mixing ratio of water, cement and aggregate, which are contained in normal concrete, is dependent on the typical standard ratio, and the slump is 0 mm. FIG. 11 illustrates a slump of 230 mm, attained by mixing the foamed slurry with the normal concrete. In FIG. 10, the air content is 3% in the normal concrete before blending the normal concrete with the foamed slurry, but in FIG. 11, the air content is remarkably increased to 26% in the mixed concrete resulting from blending the normal concrete with the foamed slurry.

(47) The increased amount of air enables the admixture to be uniformly dispersed in the normal concrete through a ball-bearing effect. However, the mixed concrete containing a large amount of air is considerably decreased in strength and durability. Typically, the relationship between the air content of normal concrete and the compressive strength thereof is such that when the air content of normal concrete is increased by 1%, compressive strength is decreased by about 4%. Specifically, the strength of the mixed concrete containing a large amount of bubbles is remarkably decreased, and is thus difficult to use as a structural material, and the slump thereof is considerably increased, undesirably resulting in poor workability when casting the mixed concrete.

(48) Hence, as illustrated in FIGS. 12 and 13, in order to decrease the large amount of air contained in the mixed concrete in the mixed concrete formation unit 130, an antifoaming agent is added to the mixed concrete, or shooting is performed using the high-performance concrete shooting unit 140.

(49) The antifoaming agent is added to the mixed concrete to remove the bubbles, which function to uniformly disperse the admixture in the normal concrete.

(50) The antifoaming agent is a material for suppressing the generation of bubbles, and may be referred to as a foam breaker for breaking the generated bubbles or a foam inhibitor for inhibiting the generation of bubbles. In the present invention, the foam breaker may be used to remove excess bubbles, which are already present. A variety of antifoaming agents may be applied to the mixed concrete, and the antifoaming agent is preferably used in an amount of 0.1 to 2.0 parts by weight based on 100 parts by weight of high-performance concrete.

(51) In the shooting of the mixed concrete using the high-performance concrete shooting unit 140, it is supplied to the inlet of the shooting guide member 141 removably attached to the agitator truck 111 of the mixed concrete formation unit 130 or the mixing member 135 of the mixed concrete formation unit 130.

(52) Here, the shooting guide member 141 is configured such that the center thereof has a smaller diameter than the inlet and outlet at respective ends, which communicate with each other, and pressure is increased while the mixed concrete guided to the shooting guide member 141 is compressed.

(53) As illustrated in FIG. 14, while the mixed concrete is passed through the center of the shooting guide member 141 and then through the outlet of the shooting guide member 141, which has a diameter greater than the center thereof, compressed air at a high pressure of 5 atm or more is fed to the air supply path 142, which is radially inclinedly formed at the outer surface of the shooting guide member 141, thereby shooting the mixed concrete in vortex form to the outlet of the shooting guide member 141. The compressed air and the mixed concrete are emitted in a spraying manner. Upon spraying, while the compressed air and the mixed concrete come into contact with each other, the large amount of bubbles contained in the mixed concrete is dissipated.

(54) As illustrated in FIGS. 15 and 16, the air content in the mixed concrete after dissipation of the bubbles is close to the air content of normal concrete before the addition of the foamed slurry. As the air content in the mixed concrete is decreased to 3 to 7%, the slump thereof is decreased to the original slump level, thereby enabling shooting of high-performance concrete having desired workability, high strength and high durability. Table 1 below shows the slump and air content of normal concrete before mixing with the foamed slurry, mixed concrete containing the foamed slurry, and high-performance concrete after shooting, with regard to dry concrete having a slump of 0 mm and typical concrete having a slump of 80 mm.

(55) TABLE-US-00001 TABLE 1 Air Kind of Slump content normal concrete State of concrete (mm) (%) Dry concrete Normal concrete 0 4.2 (slump: 0 mm) Mixed concrete containing foamed 200 26.0 slurry High-performance concrete after 0 4.3 shooting Typical concrete Normal concrete 80 6.5 (slump: 80 mm) Mixed concrete containing foamed 270 37.0 slurry High-performance concrete after 125 4.5 shooting

(56) Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, they are not to be construed as limiting the present invention. Any embodiment may be incorporated in the scope of the present invention, so long as it has substantially the same configuration as in the spirit of the claims of the invention and shows the same effects.

(57) In particular, in embodiments of the present invention, the admixture is exemplified by silica fume, metakaolin, flyash, blast slag powder, latex, and polymer, but any other admixture may be applied to the apparatus and method of the invention so long as it may improve the properties of the normal concrete and generate economic benefits.