WO2007061266A1

WO2007061266A1 - Ultra high strength concrete composition

Info

Publication number: WO2007061266A1
Application number: PCT/KR2006/005016
Authority: WO
Inventors: Seung-Hoon Lee; Gyu-Dong Kim; Yu-Shin Shon; Han-Jun Kim; Chan-Kyu Park
Original assignee: Samsung Corporation
Priority date: 2005-11-28
Filing date: 2006-11-27
Publication date: 2007-05-31

Abstract

Disclosed is an ultra-high strength concrete composition having a strength of 150 ÿ or more. The ultra-high strength concrete composition includes a binding material containing cement, fine blast furnace slag powder, silica fume, and anhydrite mixed with each other with a predetermined mixing ratio, and water at a ratio of 12 to 15 wt % to ensure a predetermined workability, and has the strength of 150 ÿ or more. The ultra-high strength concrete composition also includes a predetermined amount of fibers for preventing spalling of concrete to have the strength of 150 or more ÿ and high resistance to fire. The ultra-high strength concrete composition includes 140 to 160 ÿ of water per 1 ÿ of the concrete composition, 933 to 1333 ÿ of a binding material per 1 ÿ of concrete composition, 336 to 611 ÿ of a fine aggregate per 1 ÿ of concrete composition, and 550 to 919 ÿ of a coarse aggregate per 1 ÿ of concrete composition. A water-binding material ratio is 12 to 15 wt %, a fine aggregate ratio is 35 to 45 %, and the binding material includes cement, fine blast furnace slag powder, anhydrite, and silica fume. The high fire-resistant ultra-high strength concrete composition further includes 0.25 to 0.35 Vol % of fibers for preventing spalling of concrete based on the concrete composition.

Description

Description ULTRA HIGH STRENGTH CONCRETE COMPOSITION

Technical Field

[1] The present invention relates to an ultra-high strength concrete composition having a strength of 150 D or more and, more particularly, to an ultra-high strength concrete composition which includes a binding material containing cement, fine blast furnace slag powder, silica fume, and anhydrite mixed with each other with a predetermined mixing ratio, and water at a mixing ratio of 12 to 15 wt% to ensure a predetermined workability, and has the strength of 150 D or more.

[2] Furthermore, the present invention relates to a high fire-resistant ultra-high strength concrete composition which is mixed with a predetermined amount of fibers for preventing spalling of concrete to have the strength of 150 D or more and high resistance to fire.

[3]

Background Art

[4] Recently, due to an increase in the number of skyscrapers, ultra-high strength concrete has been used. The ultra-high strength concrete is used to reduce sectional areas of pillars, thereby reducing production cost of the frame in the case of RC structures and SRC structures. Particularly, in the case of the SRC structure, the amount of the steel frame material is significantly reduced, thus contributing to improvement in cost efficiency. In addition, since the ultra-high strength concrete is used to reduce the sectional area of the pillar, a large inner room is ensured and usefully utilized.

[5] A general ultra-high strength concrete means curable concrete that has the compressive strength of 80 D or more. Until now, cement that is mixed with silica fume, fine blast furnace slag powder, and fly ash which are industrial byproducts has been used as a binding material to produce ultra-high strength concrete of 100 to 120 D. However, a process that is applied to produce the concrete having the still better performance has not yet been developed.

[6] Meanwhile, since the ultra-high strength concrete has the very dense structure

(since the amount of water is reduced as the strength of the concrete is increased, the porosity in the concrete is reduced, and generated pore water pressure (mainly steam pressure) is not desirably reduced) in comparison with the typical concrete, the spalling of concrete becomes more serious during a fire. Accordingly, in the mixing of constituent components that constitute the ultra-high strength concrete, the ensuring of desirable strength and the control of spalling of concrete should be considered. [7]

Disclosure of Invention

Technical Problem

[8] The present invention has been made in consideration of the above disadvantages occurring in the related arts, and it is an object of the present invention to provide an ultra-high strength concrete composition which includes a binding material containing cement, fine blast furnace slag powder, silica fume, and anhydrite mixed with a predetermined mixing ratio, and water mixed with a ratio of 12 to 15 wt% to ensure a predetermined workability, and has the strength of 150 D or more.

[9] It is another object of the present invention to provide a concrete composition which is mixed with a predetermined amount of fibers for preventing spalling of concrete to have the strength of 150 D or more and high resistance to fire.

[10]

Technical Solution

[11] In order to accomplish the above objects, the present invention provides an ultrahigh strength concrete composition that includes 140 to 160 D of water per 1 D of the concrete composition, 933 to 1333 D of a binding material per 1 D of the concrete composition, 336 to 611 D of a fine aggregate per 1 D of the concrete composition, and 550 to 919 D of a coarse aggregate per 1 D of the concrete composition. A water-binding material ratio is 12 to 15 wt%, a fine aggregate ratio is 35 to 45 %, and the binding material includes cement, fine blast furnace slag powder, anhydrite, and silica fume.

[12] Furthermore, the present invention provides the high fire-resistant ultra-high strength concrete composition that further includes 0.25 to 0.35 Vol% of fibers for preventing spalling of concrete based on the concrete composition.

[13]

Best Mode for Carrying Out the Invention

[14] An ultra-high strength concrete according to the present invention includes a binding material in which cement is separately mixed with fine blast furnace slag powder, silica fume, and anhydrite with a predetermined mixing ratio, or a premixed binding material in order to improve fluidity and long-term strength. Water and the binding material are mixed with each other with a low water-binding material ratio in the concrete. The mixing ratios are described in detail in the following Table 1.

[15]

[16] Table 1

Mixing ratios of components constituting the ultra-high strength concrete

[17] [18] Meanwhile, in the ultra-high strength concrete according to the present invention, fibers for preventing spalling of concrete are mixed with the concrete composition with a predetermined mixing ratio in order to ensure resistance to fire. In this case, the mixing ratios of the constituent components are described in the following Table 2.

[19] [20] Table 2

Mixing ratios of components constituting the high fire-resistant ultra-high strength concrete

[21] [22] (1) Water-binding material ratio (W/B) [23] In order to produce the ultra-high strength concrete having the design strength of 150 MPa, the water-binding material ratio is set to 12 to 15 wt%. If the water-binding material ratio is 12 wt% or less, the fluidity of concrete is undesirable. Thus, the workability is poor. If the water-binding material ratio is 15 wt% or more, it is difficult to accomplish the object of the present invention that includes obtaining of the ultrahigh strength.

[24] (2) Fine aggregate ratio (S/a) [25] The fine aggregate ratio is a ratio of the volume of sand to the total volume of aggregate (sand + gravel), used to determine the fluidity of the concrete, and set to 35.0 to 45.0 % in consideration of the fineness modulus of the fine aggregate. Since the ultra-high strength concrete composition according to the present invention has the high weight of binding material per unit volume of concrete, the composition has high viscosity. In the case of when the ultra-high strength concrete composition also includes the large amount of fine aggregate, the viscosity is very high, thus the fluidity of the concrete may be reduced. In consideration of the above-mentioned description, in the present invention, the fine aggregate ratio is set so that desirable fluidity is obtained.

[26] (3) Water (W) [27] Water which does not contain hazardous materials (subterranean water, tap water, and so on) is used, and is the same as mixing water (water) used to produce typical concrete. In the present invention, in order to obtain ultra-high strength, the amount of water is set to 140 to 160 D/D which is a relatively low amount unlike the mixture of the typical concrete. The amount is set to prevent the fluidity from being significantly reduced and to reduce the heat of hydration.

[28] (4) Binding material (B) [29] Compounding materials such as the cement that is used in the typical concrete, the fine blast furnace slag powder, the silica fume, and the anhydrite are separately mixed with each other at a predetermined ratioto produce the binding material, or the premixed binding material is used. The compounding material improves the fluidity of concrete that is not hardened and contributes to the generation of long-term strength unlike the case of when only the cement is used. The weight of the binding material per unit volume of concrete is set to 933 to 1333 D/D so as to obtain the ultra-high strength.

[30] In the present invention, the fine blast furnace slag powder is used to reduce the heat of hydration of the cement, increase the amount of hydrate products, form a dense structure, and improve the long-term strength. In addition, anhydrites are used to act as a stimulant of the fine blast furnace slag powder that is a potential hydraulic material and to form the dense structure due to an effective expansion. Furthermore, the silica fume that is already known to be useful to ensure the ultra-high strength is used.

[31] In the case of when the fine blast furnace slag powder having a high fineness of 3,500 to 7,500 D/g and the anhydrite having a high fineness of 4,500 to 6,500 D/g are used, the fine blast furnace slag powder and the anhydrite are desirably mixed with each other and desirably dispersed to improve the fluidity and the strength.

[32] The mixing ratio of the cement and the compounding material is described in the following Table 3 in consideration of the fluidity and the strength of the concrete.

[33] [34] Table 3 Mixing ratios of components constituting the binding material

[35] [36] (5) Fine aggregate (S)

[37] Examples of the fine aggregate (sand) include typical fine aggregate that is used in a ready-mixed concrete company. It is preferable that a fineness modulus of the fine aggregate be 2.8 to 3.0 in order to ensure desirable fluidity of the concrete and reduce the viscosity. The weight of fine aggregate per unit volume of concrete is set to 336 to 611 D/D.

[38] (6) Coarse aggregate (G)

[39] Preferably, the maximum particle size of the coarse aggregate (gravel) is set to 20 D or less in consideration of the strength of the concrete, and the aggregate has a strength of 150 D or more. The weight of the coarse aggregate per unit volume of concrete is set to 550 to 919 D/D.

[40] In connection with this, in the case of when the high fire-resistant ultra-high strength concrete composition that is mixed with the predetermined amount of fibers fo r preventing spalling of concrete, it is preferable to use the aggregate having a strength of 150 D or more and a desirable resistance to fire at 1200⁰C.

[41] (7) Chemical admixture(AD) : polycarboxylate based high-range water reducing agent

[42] Since the ultra-high strength concrete composition according to the present invention has the low water-binding material ratio, it is preferable to further add the high-range water reducing agent. In connection with this, examples of the high-range water reducing agent include the polycarboxylate based high-range water reducing agent having excellent dispersing ability and water reduction. In consideration of cost efficiency and performance, the polycarboxylate based high-range water reducing agent is preferably mixed so that the amount of polycarboxylate based high-range water reducing agent be 2.0 to 3.5 wt% based on the amount of the binding material.

[43] (8) Shrinkage reducing agent (WRA)

[44] Since the more self- shrinkage occurs in the ultra-high strength concrete as compared with the typical concrete, it is important to control the self-shrinkage at an early step of the curing. Accordingly, since it is necessary to reduce the shrinkage by drying in respect to the long-term usage, it is preferable that the amount of shrinkage reducing agent be 1.0 to 2.0 wt% of the binding material.

[45] (9) Fibers for preventing spalling of concrete : polypropylene (PP) fibers

[46] In order to control the spalling of the ultra-high strength concrete that has a dense structure after the curing, in the present invention, the fibers for preventing spalling of concrete are added. The amount of fibers for preventing spalling of concrete is set so that the strength of the concrete is not reduced. To be more specific, it is preferable that the amount of fibers be 0.25 to 0.35 vol% based on the concrete.

[47] Mode for the Invention

[48] Preferred examples of the present invention will be described in detail hereinafter. [49] [EXAMPLE 1] Semi Mock-Up of the ultra-high strength concrete [50] (1) Testing method [51] In the case of test sample 1, the ultra-high strength concrete was applied into a box having a size of l m x l m x l m to evaluate the workability and to measure compressive strengths of specimens and strengths of cores according to the age, and it was examined whether the desired strength was obtained or not. In the case of test sample 2, the concrete was applied into a box having a size of 1 m x 1 m x 1.5 m.

[52] (2) Ultra-high strength concrete mixing design [53] In the present example, the concrete mixing design and the material sources are described in the following Table 4.

[54] [55] Table 4 Ultra-high strength concrete mixing design

[56] (3) Test result [57] Physical properties of the concrete that was mixed according to the mixing design were tested, and the results are described in the following Tables 5 and 6.

[58] [59] Table 5 Test result of physical properties of the concrete that is not hardened

[60] [61] Table 6 Test result of the cured concrete

[62] [63] In the test of the physical properties of the concrete that was not hardened, the slump flows of test samples 1 and 2 after 40 min were 69 D or more. Accordingly, the desirable workability was obtained. In the test result of the cured concrete, the specimen satisfied the strength of 150 D that corresponded to the design standard when the age was 56 days. With respect to the strength of the core, the strength satisfied the design standard when the age was 3 days due to generation of the early heat of hydration.

[64] [EXAMPLE 2] Mock-Up of the ultra-high strength concrete [65] (1) Testing method [66] Based on the results of Example 1, the ultra-high strength concrete was applied into the model of the member that was provided with pillars and walls to evaluate the workability and to measure compressive strengths of specimens and strengths of cores according to the age, and it was examined whether the desired strength was obtained or not.

[67] (2) Ultra-high strength concrete mixing design [68] The ultra-high strength concrete mixing design and the material sources were the same as those of test sample 1 of Example 1. [69] (3) Test result [70] Site arrival physical properties of the concrete that was mixed according to the mixing design were tested, and the results are described in the following Tables 7 and 8.

[71] [72] Table 7 Result of physical properties of the concrete that is not hardened

[73] [74] Table 8 Test result of the cured concrete

[75] [76] In the test of the physical properties of the concrete that was not hardened, the site arrival slump flow was 65 D or more. This meant that the fluidity was desirable during the application of the concrete. In the test result of the cured concrete, in the case of the specimen, the strength was 140 D when the age was 28 days, and the strength was 150 D or more that was the design standard strength when the target age was 56 days. With respect to the strength of the core, the strength satisfied the design standard when the age was 3 days due to generation of the early heat of hydration.

[77] [EXAMPLE 3] Mock- Up of high fire-resistant ultra-high strength concrete [78] (1) Testing method [79] The high fire-resistant ultra-high strength concrete was applied into the model of the pillar member to evaluate the workability and to measure compressive strengths of specimens and strengths of cores according to the age, and it was examined whether the desired strength was obtained or not.

[80] (2) High fire-resistant ultra-high strength concrete mixing design [81] In the present example, the concrete mixing design and the material sources are described in the following Table 9. [83] Table 9

High fire-resistant ultra-high strength concrete mixing design

[84] [85] (3) Test result [86] Physical properties of the concrete that was mixed according to the mixing design were tested, and the results are described in the following Tables 10 and 11.

[87] [88] Table 10 Test result of physical properties of the concrete that is not hardened

[89] [90] Table 11 Test result of the cured concrete

[91] [92] In the test of the physical properties of the concrete that was not hardened, the site arrival slump flow was 58 D or more. This meant that the fluidity was desirable during the application of the concrete. In the test result of the cured concrete, in the case of the specimen, the strength was 131.5 D when the age was 28 days, and in the case of the core specimen, the strength was 143.1 D when the age was 28 days. The specimens satisfied the strength of 150 D that corresponded to the design standard when the age was 91 days that corresponded to the target age. Through the typical test of the resistance to fire, it can be expected that the resistance to fire is improved because the fibers for preventing spalling of concrete are added.

[93]

Industrial Applicability

[94] According to the present invention, during the concrete mixing design, a binding material in which cement is mixed with fine blast furnace slag powder, silica fume, and anhydrite at a predetermined ratio is used, and the mixing is performed at a low water- binding material ratio of 12 to 15 wt%. Thus, desirable workability is ensured, and concrete that has ultra-high strength of more than 150 D is produced. Accordingly, if the ultra-high strength concrete is used to construct skyscrapers, it is expected that a sectional area of the frame can be significantly reduced, construction can be effectively performed, and a large interior space can be ensured.

[95] In addition, since a predetermined amount of fibers for preventing spalling of concrete is added to ensure desirable resistance to fire, the desirable safety is ensured against a fire when high fire-resistant ultra-high strength concrete is used to construct skyscrapers.

[96]

Claims

Claims[1] An ultra-high strength concrete composition comprising:140 to 160 D of water per 1 D of the concrete composition;933 to 1333 D of a binding material per 1 D of concrete composition;336 to 611 D of a fine aggregate per 1 D of concrete composition; and550 to 919 D of a coarse aggregate per 1 D of concrete composition, wherein a water-binding material ratio is 12 to 15 wt%, a fine aggregate ratio is35 to 45 %, and the binding material includes cement, fine blast furnace slag powder, anhydrite, and silica fume. [2] The ultra-high strength concrete composition of claim 1, wherein the binding material includes:60 to 65 wt% of cement;15 to 20 wt% of fine blast furnace slag powder;5 to 10 wt% of anhydrite; and8 to 15 wt% of silica fume. [3] The ultra-high strength concrete composition of claim 2, wherein a fineness of the fine blast furnace slag powder is 3,500 to 7,500 D/g, and a fineness of the anhydrite is 4,500 to 6,500 D/g. [4] The ultra-high strength concrete composition of any one of claims 1 to 3, wherein a fineness modulus of the fine aggregate is 2.8 to 3.0, and the coarse aggregate has a maximum size of 20 D or less and a strength of 150 D or more. [5] The ultra-high strength concrete composition of claim 4, further comprising:2.0 to 3.5 wt% of a polycarbonate based high-range water reducing agent based on the binding material. [6] The ultra-high strength concrete composition of claim 5, further comprising:

1.0 to 2.0 wt% of a shrinkage reducing agent based on the binding material. [7] The ultra-high strength concrete composition of any one of claims 1 to 3, further comprising:

0.25 to 0.35 Vol% of fibers for preventing spalling of concrete based on the concrete composition. [8] The ultra-high strength concrete composition of claim 7, wherein a fineness modulus of a fine aggregate is 2.8 to 3.0, and a coarse aggregate has a maximum size of 20 D or less, and a strength of 150 D or more, and a predetermined resistance to fire at 1200⁰C. [9] The ultra-high strength concrete composition of claim 8, further comprising:

2.0 to 3.5 wt% of a polycarbonate based high-range water reducing agent based on a binding material.