Concrete composition and concrete member

Abstract

To provide a concrete composition and a concrete member excellent in fire resistance.SOLUTION: A concrete composition according to the present invention contains a hydraulic composition containing water and a binder, and a fiber. The fiber is a polyester fiber. The concrete composition according to the present invention preferably has a compressive strength of 50 N / mm2 or more. In the concrete composition according to the present invention, a fiber length of the fiber is preferably 35-55 mm. The concrete member according to the present invention is composed of the concrete composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a concrete composition and a concrete member made of the concrete composition. [Background technology]

[0002] The majority of carbon dioxide (CO2) emitted in the production of concrete materials comes from the production of Portland cement. Therefore, using blast furnace slag instead of Portland cement would enable a significant reduction in CO2 emissions, contributing to the realization of a decarbonized society. As shown in Patent Document 1, the present applicant has developed and put into practical use "environmentally friendly concrete" that uses a hydraulic composition containing blast furnace slag as the main binder. Furthermore, as shown in Patent Document 2, the applicant has reported that in order to improve the fire resistance of "environmentally friendly concrete", polypropylene fibers (fire-resistant organic fibers) are added to the hydraulic composition 1 m. 3 It has been confirmed that it is sufficient to contain 3kg or more per unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6873663 [Patent Document 2] Japanese Patent Application Publication No. 2023-77790 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as shown in Patent Document 2, if concrete contains a large amount of polypropylene fibers, the viscosity of the concrete may become excessive, which may cause poor filling, etc. (unless the viscosity is reduced by using a large amount of admixture separately). Therefore, the present inventors wanted to create a new technology different from the technology of Patent Document 2 in order to improve the fire resistance of "environmentally friendly concrete." In addition, since the need for "improved fire resistance" of concrete is not limited to environmentally friendly concrete, the inventors wanted to create a new technology that could be applied to various types of concrete.

[0005] From this perspective, an object of the present invention is to provide a concrete composition and a concrete member having excellent fire resistance. [Means for solving the problem]

[0006] The above problems can be solved by the following means. The concrete composition according to the present invention is a concrete composition containing a hydraulic composition containing water and a binder, and fibers, wherein the fibers are polyester fibers. As described above, the concrete composition according to the present invention has excellent fire resistance because it contains polyester fibers. The concrete composition according to the present invention has a compressive strength of 50 N / mm 2 In this way, the concrete composition according to the present invention has a compressive strength specified to be equal to or greater than a predetermined value, and therefore can ensure a desired strength. In the concrete composition according to the present invention, when the binder is ordinary Portland cement, the content of the fibers is 3 When the binder is blast furnace cement type B, the content of the fibers is 0.4 kg or more per 1 m of the hydraulic composition. 3 When the binder contains blast furnace slag and an activator, the content of the fibers is 0.2 kg or more per 1 m of the hydraulic composition. 3 Preferably, the fiber weight is 0.8 kg or more per unit area. Furthermore, in the concrete composition according to the present invention, the fiber length of the fibers is preferably 35 to 55 mm. As described above, the concrete composition according to the present invention satisfies each of the requirements, and therefore can more reliably exhibit excellent fire resistance. The concrete member according to the present invention is made of the concrete composition described above. As described above, the concrete member according to the present invention is made of a concrete composition containing polyester fibers, and therefore has excellent fire resistance. [Effects of the Invention]

[0007] The concrete composition and concrete member according to the present invention have excellent fire resistance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a graph showing the weight ratio of Samples 1-1 to 1-9 after heating to that before heating. [Figure 2] 1 is a graph showing the weight ratio of Samples 2-1 to 2-9 after heating to that before heating. [Figure 3] 1 is a graph showing the weight ratio of Samples 3-1 to 3-6 after heating to that before heating. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present inventors have investigated many materials to select a material that can replace polypropylene fibers, which improves the fire resistance of concrete compositions. As a result, the present inventors have discovered various useful properties of polyester fibers (such as the ability to improve the fire resistance of various concrete compositions, the ability to reduce the amount of polyester fibers mixed in, and the ability to reduce costs), and have created the present invention. Therefore, the concrete composition according to this embodiment contains polyester fibers.

[0010] Below, we will explain the concrete compositions for each type of binder, including the first embodiment (in which the binder is ordinary Portland cement), the second embodiment (in which the binder is blast-furnace cement type B), and the third embodiment (in which the binder contains blast-furnace slag and a stimulant). In describing the second and third embodiments, the description of the common features with the embodiments already described will be omitted, and the description will focus on the differences.

[0011] [First embodiment: Concrete composition in which the binder is ordinary Portland cement] (polyester fiber) Polyester fiber is a type of synthetic fiber made of polyester (PEs), a polymer compound with ester bonds. Polyester fibers include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and composite fibers that combine these fibers. More specifically, examples of polyester fibers include those manufactured by Toray Industries, Inc., Teijin Limited, and Fujibo Co., Ltd.

[0012] (Polyester fiber: Examples of physical properties) The physical properties of the polyester fiber are not particularly limited, but are, for example, as follows. Fiber length: 35-55mm, 38-51mm Fineness: 3.5~5.5dtex, 4.0~4.8dtex Strength: 2.0~3.5cN / dtex, 2.5~3.0cN / dtex Elongation: 40.0-60.0%, 45.0-55.0% Number of crimp: 5.0~15.0No / 25mm, 8.0~12.0No / 25mm Crimp degree: 10.0~20.0%, 12.0~16.0% Density: 0.80~2.00g / cm 3 , 1.20~1.50g / cm 3

[0013] (Polyester fiber: content) The content of polyester fiber in the concrete composition according to the first embodiment is 1 / m of hydraulic composition. 3 The content of polyester fiber is preferably 0.4 kg or more, more preferably 0.5 kg or more, per unit area. When the content of polyester fiber is equal to or more than the predetermined value, the fire resistance of the concrete composition can be made excellent. The upper limit of the content of polyester fiber is not particularly limited. For example, 3 The maximum per unit is 3.0 kg, 2.0 kg, and 1.8 kg.

[0014] (Binding material) The binder of the concrete composition according to the first embodiment is ordinary Portland cement, which is specified in JIS R5210:2009. The content of ordinary Portland cement in the hydraulic composition is, for example, 350 kg / m 3 More than 400kg / m 3 More than 450kg / m 3 or more, 700 kg / m 3 Below 600kg / m 3 Below 500kg / m 3 The following is the result.

[0015] (water) The water is not particularly limited, and tap water, groundwater, sludge water, etc. can be used. Water-binder ratio (= water content (kg / m 3 ) / binder content (kg / m 3 ) × 100) is, for example, 20% or more, 23% or more, 28% or more, 30% or more, and 45% or less, 40% or less, 35% or less.

[0016] (aggregate) The aggregate is not particularly limited, and examples thereof include fine aggregate and coarse aggregate. Examples of fine aggregates include mountain sand, river sand, sea sand, crushed sand, silica sand, and lime sand, and examples of coarse aggregates include mountain gravel, river gravel, and sea gravel. All of these can be used in accordance with JISA5005:2020. The content of fine aggregate in the hydraulic composition is, for example, 500 kg / m 3 More than 600kg / m 3 More than 650kg / m 3 or more, 1000 kg / m 3 Below 900kg / m 3 Below 800kg / m 3The content of the coarse aggregate in the hydraulic composition is, for example, 600 kg / m or less. 3 More than 800kg / m 3 More than 900kg / m 3 or more, 1200 kg / m 3 Below 1100kg / m 3 Below 1080kg / m 3 The following is the result.

[0017] (Other ingredients) The concrete composition may contain, as appropriate, conventionally known materials used in concrete (such as chemical admixtures specified in JISA6204:2011) to the extent that the desired effects of the present invention are not impaired.

[0018] (Physical properties: compressive strength) The compressive strength of the concrete composition is 50 N / mm 2 The above is preferable. When the compressive strength is equal to or greater than a predetermined value, it is possible to ensure an appropriate strength for the concrete member (hardened body). Here, the "compressive strength" specifically refers to the compressive strength at an age of 28 days, and can be measured by the test method described in JISA1108:2018.

[0019] (Physical properties: slump value) The slump value of the concrete composition is preferably 10.0 cm or more, and more preferably 13.0 cm or more. When the slump value is a predetermined value or more, workability can be ensured (poor filling due to excessive viscosity can be avoided). The slump value can be measured by the test method described in JISA1101:2020.

[0020] [Second embodiment: Concrete composition in which the binder is blast furnace cement type B] (Polyester fiber: content) The content of polyester fiber in the concrete composition according to the second embodiment is 1 / m of hydraulic composition. 3The content of polyester fiber is preferably 0.2 kg or more, and more preferably 0.3 kg or more, per unit area. When the content of polyester fiber is equal to or more than the predetermined value, the fire resistance of the concrete composition can be made excellent. The upper limit of the content of polyester fiber is not particularly limited. For example, 3 The maximum per unit is 3.0 kg, 2.0 kg, and 1.8 kg.

[0021] (Binding material) The binder of the concrete composition according to the second embodiment is blast furnace cement type B. The blast furnace cement type B is specified in JIS R5211:2009. The content of blast furnace cement type B in the hydraulic composition is, for example, 350 kg / m 3 More than 400kg / m 3 More than 450kg / m 3 or more, 700 kg / m 3 Below 600kg / m 3 Below 500kg / m 3 The following is the result.

[0022] The water, aggregate, other materials, and physical properties of the concrete composition according to the second embodiment are the same as those of the first embodiment.

[0023] [Third embodiment: Concrete composition in which the binder contains blast furnace slag and stimulant] (Polyester fiber: content) The content of polyester fiber in the concrete composition according to the third embodiment is 1 / m of hydraulic composition. 3 The content of polyester fiber is preferably 0.8 kg or more, and more preferably 1.0 kg or more, per unit area. When the content of polyester fiber is equal to or more than the predetermined value, the fire resistance of the concrete composition can be made excellent. The upper limit of the content of polyester fiber is not particularly limited. For example, 3 The maximum per unit is 3.0 kg, 2.0 kg, and 1.8 kg.

[0024] (Binding material) The binder of the concrete composition according to the third embodiment contains blast furnace slag and a stimulant. Preferably, the binder in the third embodiment does not contain Portland cement, which contributes to CO2 emissions. This type is also known as a "zero-cement" or "environmentally friendly" type. Blast furnace slag (ground granulated blast furnace slag) is specified in JISA6206:2013. Stimulants are substances that stimulate hardening, such as slaked lime, quicklime, expansive materials (JISA6202:2017), and Portland cement (JISR5210:2009). Lime-based expansive materials are preferred. The content of binder in the hydraulic composition (total amount of blast furnace slag, stimulant, etc.) is, for example, 350 kg / m 3 More than 400kg / m 3 More than 450kg / m 3 or more, 800 kg / m 3 Below 700kg / m 3 Below 600kg / m 3 The following is the result.

[0025] The water, aggregate, other materials, and physical properties of the concrete composition according to the third embodiment are the same as those of the first embodiment.

[0026] [Another embodiment] In the first embodiment, the case where ordinary Portland cement is used as the binder has been described. However, instead of ordinary Portland cement, it is also possible to use high-early-strength Portland cement, extra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, sulfate-resistant Portland cement, or the like as specified in JIS R5210:2009, and one or more types of these may be used.

[0027] In this specification, a "hydraulic composition" refers to a composition that hardens with water, and contains at least water and a binder, and may also contain aggregate, admixtures (fly ash, silica fume, limestone fine powder, calcium carbonate, etc.), and other materials. A "hydraulic composition" may be a composition in which both coarse aggregate and fine aggregate are mixed as aggregates (so-called "concrete"), or a composition in which only fine aggregate is mixed as aggregate (so-called "mortar"). A "concrete composition" is a composition in which polyester fibers are mixed into a hydraulic composition. In this specification, the content of polyester fiber refers to the amount added as a percentage to the hydraulic composition.

[0028] [Concrete members] The concrete member according to this embodiment is a member (hardened body after construction) made of the above-mentioned concrete composition. Furthermore, since the concrete member according to this embodiment is made of a concrete composition containing polyester fibers, it not only has excellent fire resistance, but also exhibits the desired strength and excellent workability.

[0029] [Method for producing a concrete composition and method for producing a concrete member] The method for producing a concrete composition according to this embodiment includes the steps of preparing the above-described materials, and the method for producing a concrete member according to this embodiment includes the steps of mixing, pouring, curing, etc., after the above-described steps. The treatment in each step may be carried out under conditions generally used for producing a concrete composition or a concrete member. [Example]

[0030] [sample] Each of the samples shown in Tables 4 to 7 used in the examples was based on the formulation (hydraulic composition formulation) shown in Tables 1 to 3, and polyester fibers or polypropylene fibers were mixed in. The materials listed in Tables 1 to 3 are as follows: W: Water (groundwater) C1: Ordinary Portland cement, density 3.16g / cm 3 C2: Blast-furnace cement type B, density 3.04 g / cm 3 BS: Ground granulated blast furnace slag, density 2.89 g / cm 3 CH: Lime-based expansive material density 3.15g / cm 3 Ex: Slaked lime special density 2.20g / cm 3 S: Mountain sand density 2.61g / cm 3 G: Crushed stone, density 2.65g / cm 3 AD1: High-performance water reducer AD2: High-performance water reducer Table 8 shows the detailed specifications of each material.

[0031] The fibers listed in Tables 4 to 7 are as follows: (polyester fiber) Toray Industries, Inc. T9611‐4.4×38mm or 51mm Fiber length: 38mm or 51mm Fineness: 4.4 dtex Strength: 2.7cN / dtex Elongation: 47.3% Number of crimp: 10.0No / 25mm Crinkage degree: 14.0% Density: 1.35g / cm 3 (Polypropylene fiber) Teijin Fiber length: 51mm Fineness: 3.3dtex

[0032] (Test content: Heating test) For the specimens used in the heating test, the materials listed in the table were mixed and then poured into a formwork (inner diameter 10 mm, height 20 mm, cylindrical). After that, the mixture was steam cured (held at 50°C for 3 hours), and then cured at ambient temperature for up to 91 days to create the specimens. Then, a heating test was conducted on each of the prepared specimens by heating them in a small furnace. The temperature inside the small furnace used in the heating test was adjusted so that it rose to 1200°C within 5 minutes of starting heating, maintained at 1200°C for approximately 55 minutes, and then allowed to cool naturally. In other words, the temperature inside the furnace was adjusted to conform to the RABT curve.

[0033] In the heating test, the weight of each specimen was measured before and after heating, and the "weight ratio after heating to that before heating" (= weight of specimen after heating / weight of specimen before heating) was calculated. In addition, each specimen after the heating test was visually inspected to see if there was any deformation (×) or not (◯).

[0034] (Test content: Compression strength test) For the specimens used in the compressive strength tests, the materials listed in the table were mixed and then poured into a formwork (inner diameter 10 mm, height 20 mm, cylindrical). The mixture was then steam cured (held at 50°C for 3 hours), and then cured at ambient temperature for up to 91 days to create the specimens. Then, compressive strength tests were conducted on each of the specimens prepared in accordance with JISA1108:2018.

[0035] (Test content: Slump test) The slump test was carried out on each sample (concrete composition) after mixing in accordance with JISA1150:2020.

[0036] The table shows the composition of each sample and the results of each test. In the table showing the amount of high-performance water reducer (AD) added, "C x %" is the ratio (percentage) to the mass of the binder, cement C (C1 or C2), "B x %" is the ratio (percentage) to the mass of binder B, and "s / a" is the fine aggregate ratio. Also, "-" in the test results in the table indicates that the test was not conducted.

[0037] [Table 1]

[0038] [Table 2]

[0039] [Table 3]

[0040] [Table 4]

[0041] [Table 5]

[0042] [Table 6]

[0043] [Table 7]

[0044] [Table 8]

[0045] (Discussion of results) 1 to 3 are graphs showing the weight ratio of each sample after heating to that before heating, with FIG. 1 being the graph for samples 1-1 to 1-9, FIG. 2 being the graph for samples 2-1 to 2-9, and FIG. 3 being the graph for samples 3-1 to 3-6.

[0046] (Discussion of Results: Concrete Compositions with Ordinary Portland Cement as Binder) According to the results of Figure 1 and Table 4, when ordinary Portland cement was used as a binder, polyester fiber was 3It was confirmed that if the content is 0.4 kg or more (especially 0.5 kg or more) per unit, deformation can be suppressed and the weight ratio after heating to before heating can be made higher.In other words, it is possible to suppress damage (peeling, explosion, etc.) in the event of a fire, etc., and therefore it has excellent fire resistance. Furthermore, the results of Figure 1 and Table 4 show that the compressive strength and fresh properties were good, and it was confirmed that when ordinary Portland cement is used as the binder, strength and workability can be ensured even when polyester fiber is used. Furthermore, by comparing the results of Figure 1 and Table 4 with the results of Samples 4-1 to 4-3 in Table 7, it was confirmed that the amount of polyester fiber required to achieve excellent fire resistance was less than that of polypropylene fiber. In addition, it was also confirmed that the use of polyester fiber resulted in better workability than the use of polypropylene fiber.

[0047] (Discussion of results: Concrete composition with blast furnace cement type B as binder) According to the results of Figure 2 and Table 5, when blast furnace cement type B was used as the binder, polyester fiber 3 It was confirmed that if the content is 0.2 kg or more (especially 0.3 kg or more) per unit, deformation can be suppressed and the weight ratio after heating to before heating can be made higher.In other words, it is possible to suppress damage (peeling, explosion, etc.) in the event of a fire, etc., and therefore it has excellent fire resistance. Furthermore, the results of Figure 2 and Table 5 show that the compressive strength and fresh properties were also good, confirming that when blast-furnace cement type B is used as the binder, strength and workability can be ensured even when polyester fiber is used. Furthermore, by comparing the results of Figure 2 and Table 5 with the results of Samples 4-4 to 4-6 in Table 7, it was confirmed that the amount of polyester fiber required to achieve excellent fire resistance was less than that of polypropylene fiber. In addition, it was also confirmed that the use of polyester fiber resulted in better workability than the use of polypropylene fiber.

[0048] (Discussion of Results: Concrete Compositions with Binders Containing Blast Furnace Slag and Stimulants) According to the results of Figure 3 and Table 6, when blast furnace slag and stimulant were used as binders (zero type), polyester fiber was used for 1 m of hydraulic composition. 3 It was confirmed that if the content is 0.8 kg or more (especially 1.0 kg or more) per unit, deformation can be suppressed and the weight ratio after heating to before heating can be made higher.In other words, damage (peeling, explosion, etc.) in the event of a fire can be suppressed, and therefore excellent fire resistance can be confirmed. Furthermore, the results of Figure 3 and Table 6 show that the compressive strength and fresh properties were good, and it was confirmed that when blast furnace slag and stimulating agent are used as binders, strength and workability can be ensured even when polyester fiber is used. Furthermore, by comparing the results of Figure 3 and Table 6 with the results of Samples 4-7 to 4-9 in Table 7, it was confirmed that the amount of polyester fiber required to achieve excellent fire resistance was significantly less than that of polypropylene fiber. In addition, it was also confirmed that the use of polyester fiber resulted in better workability than the use of polypropylene fiber.

Claims

1. A concrete composition containing a hydraulic composition containing water and a binder, and fibers, A concrete composition characterized in that the fibers are polyester fibers.

2. Compression strength: 50 N / mm ２ 2. The concrete composition according to claim 1, wherein the concrete composition is a mixture of the above.

3. When the binder is ordinary Portland cement, the content of the fibers is ３ per 0.4 kg or more, When the binder is blast furnace cement type B, the content of the fibers is ３ per 0.2 kg or more, When the binder contains blast furnace slag and an activator, the content of the fiber is ３ 3. The concrete composition according to claim 1, wherein the weight of the concrete composition is 0.8 kg or more per unit weight.

4. 3. The concrete composition according to claim 1, wherein the fibers have a fiber length of 35 to 55 mm.

5. A concrete member comprising the concrete composition according to claim 1 or 2.

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