Hydraulic composition and wall member

Abstract

To provide a hydraulic composition and a wall member, capable of reducing an amount of emission of CO2, stably holding or storing CO2, and improving fire-resistance performance.SOLUTION: A hydraulic composition includes water, a binder, calcium carbonate, aggregate, and organic fibers. The binder includes at least one kind among blast furnace slag, an expansive admixture, and hydrated lime. A ratio of the calcium carbonate in powders consisting of the binder and the calcium carbonate is in a range of 8.6-45 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hydraulic composition containing calcium carbonate, and a wall member formed from this hydraulic composition. [Background technology]

[0002] Portland cement, which is a binder in hydraulic compositions such as concrete and mortar, emits carbon dioxide (CO2) during its manufacture. Therefore, in some cases, CO2 emissions are reduced by using blast furnace slag or fly ash instead of Portland cement (see, for example, Patent Document 1). In recent years, technologies have been developed to capture CO2 and produce calcium carbonate. The calcium carbonate produced by this technology fixes CO2 from the atmosphere and exhaust gases. By incorporating the above-mentioned calcium carbonate into hydraulic compositions, CO2 can be fixed or stored, thereby achieving a negative CO2 balance. Incidentally, when concrete members are exposed to high temperatures, the water in the concrete vaporizes and expands, which can cause a phenomenon called spalling (surface cracking). In particular, high-strength concrete is known to be more prone to spalling than ordinary concrete because its structure is denser. When a concrete member spalls, its cross-section becomes narrower, and the internal temperature rises rapidly, reducing its load-bearing capacity and durability. As a technology to suppress the occurrence of spalling, for example, Patent Document 2 describes a design standard strength of 60 N / mm² containing Portland cement. 2 For ultra-high-strength concrete exceeding a certain level, a bombardment-resistant concrete containing organic fibers has been disclosed. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-148434 [Patent Document 2] Japanese Patent Publication No. 2017-124958 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Even concrete containing calcium carbonate and not Portland cement carries a risk of spalling. The present invention aims to propose a hydraulic composition that reduces CO2 emissions, ensures stable retention and storage of CO2, and improves fire resistance, as well as a wall member utilizing this hydraulic composition. [Means for solving the problem]

[0005] The inventors of the present invention have found that by adjusting the content of organic fibers and calcium carbonate in a hydraulic composition containing a binder containing at least one of blast furnace slag, an expansive agent, and slaked lime, the occurrence of explosions can be suppressed even when exposed to high temperatures after hardening, and have come up with the present invention. Specifically, the present invention is a hydraulic composition containing powder, organic fibers, and water, wherein the powder consists of a binder and calcium carbonate, the binder does not contain Portland cement and contains at least one of blast furnace slag, an expansive agent, and slaked lime, and the proportion of calcium carbonate in the powder is in the range of 8.6% to 45% by mass, more preferably in the range of 33% to 45% by mass. This hydraulic composition makes it possible to reduce CO2 emissions, and the use of calcium carbonate enables the stable retention and storage of CO2. Furthermore, the inclusion of organic fibers suppresses spalling when exposed to high temperatures. If wall members formed from the hardened body of this hydraulic composition are used, damage due to spalling will be suppressed even when exposed to high temperatures during a fire or other incident. Such wall members are preferably 150 mm or thicker. Calcium carbonate contains, Light It is preferable to use calcium carbonate. In addition ,before Organic fibers teeth, The aforementioned powder 1 m 3It is added within the range of 1.0 kg or more and 3.0 kg or less per unit area. ru. Also, from the viewpoint of ensuring good fluidity before curing, the slump flow value measured in accordance with "JIS A 1150 (Method for Slump Flow Test of Concrete)" is preferably 40 cm or more.

Advantages of the Invention

[0006] According to the hydraulic composition and wall member of the present invention, it is possible to reduce the CO2 emission amount and stably hold and store CO2, and further improve the fire resistance performance.

Brief Description of the Drawings

[0007] [Figure 1] It is a view showing the arrangement of the furnace and the specimen in the heating experiment, where (a) is a front view and (b) is a cross-sectional view. [Figure 2] It is a graph showing the temperature inside the furnace during the heating experiment, where (a) shows Mix A and (b) shows Mix B. [Figure 3] It is a graph showing the temperature inside the furnace during the heating experiment of Mix C. [Figure 4] It is a photograph showing the specimen after the heating experiment, where (a) is Mix A, (b) is Mix B, and (c) is Mix C. [Figure 5] It is a graph showing the weight ratio of the specimen before and after the heating experiment, where (a) is Mix A and (b) is Mix B. [Figure 6] It is a graph showing the weight ratio of the specimen before and after the heating experiment of Mix C. [Figure 7] It is a view showing a small wall specimen, where (a) is a front view and (b) is a cross-sectional view of (a). [Figure 8] It is a view showing the arrangement of the furnace and the small wall specimen in the heating experiment for the small wall specimen, where (a) is a front view and (b) is a cross-sectional view. [Figure 9] (a) is a graph showing the average temperature inside the furnace at each time during the heating experiment of Example A-21, and (b) is a graph showing the non-heated surface temperature of the small wall specimen at each time during the heating experiment of Example A-21. [Figure 10] (a) is a graph showing the average temperature inside the furnace over time during the heating experiment of Example A-22, and (b) is a graph showing the unheated surface temperature of the small wall test specimen over time during the heating experiment of Example A-22. [Figure 11] (a) is a graph showing the average temperature inside the furnace over time during the heating experiment of Example A-23, and (b) is a graph showing the unheated surface temperature of the small wall test specimen over time during the heating experiment of Example A-23. [Figure 12] (a) is a graph showing the average temperature inside the furnace over time during the heating experiment of Example B-21, and (b) is a graph showing the unheated surface temperature of the small wall test specimen over time during the heating experiment of Example B-21. [Figure 13] (a) is a photograph showing the heated surface of the small wall test specimen of Example A-21 before the heating experiment, and (b) is a photograph showing the heated surface of the small wall test specimen of Example A-21 before the heating experiment. [Figure 14] (a) is a photograph showing the heated surface of the small wall test specimen of Example A-22 before the heating experiment, and (b) is a photograph showing the heated surface of the small wall test specimen of Example A-22 before the heating experiment. [Figure 15] (a) is a photograph showing the heated surface of the small wall test specimen of Example A-23 before the heating experiment, and (b) is a photograph showing the heated surface of the small wall test specimen of Example A-23 before the heating experiment. [Figure 16] (a) is a photograph showing the heated surface of the small wall test specimen of Example B-21 before the heating experiment, and (b) is a photograph showing the heated surface of the small wall test specimen of Example B-21 before the heating experiment. [Modes for carrying out the invention]

[0008] In this embodiment, we will describe the concrete used when constructing a reinforced concrete building. The concrete (hydraulic composition) of this embodiment is prepared by mixing water, a binder, calcium carbonate, aggregate, and polypropylene fibers. The concrete mix shall be designed so that the slump flow value, measured in accordance with JIS A 1150, is 40 cm or higher.

[0009] The binder consists of blast furnace slag, an expansive agent, and slaked lime, but does not contain Portland cement. For blast furnace slag, it is desirable to use blast furnace slag fine powder that conforms to JIS (Japanese Industrial Standards) R5211 "Blast Furnace Cement" or JIS A6206 "Blast Furnace Slag for Concrete". Furthermore, the blast furnace slag should have a specific surface area of ​​2000 to 10000 cm². 2 / g, preferably 3500-7000cm 2 It is preferable to use the / g type. For the expansive agent, for example, an expansive agent specified in JIS A6202 "Expansive Agents for Concrete" may be used. It is desirable to add the expansive agent at a ratio of 2 to 9% by mass relative to the total hydraulic composition. For slaked lime, you can use, for example, the type specified in JIS R9001 "Industrial Lime". Also, since quicklime turns into slaked lime when it comes into contact with water, you can use, for example, quicklime specified in JIS R9001 "Industrial Lime" as a substitute for slaked lime. In this case, it is advisable to adjust the amount of water required for the quicklime to change into slaked lime.

[0010] Calcium carbonate (CaCO3) is added to the powder, with its proportion of the binder and calcium carbonate ranging from 8.6% to 45% by mass. Suitable calcium carbonates include natural calcium carbonate called heavy calcium carbonate, obtained by crushing and classifying limestone, and synthetic calcium carbonate called light calcium carbonate, produced by precipitating fine crystals through chemical reactions. Calcium carbonate produced by recovering CO2 can also be treated as light calcium carbonate, as it is synthesized through the reaction of calcium and CO2. Polypropylene fibers are in powder form (binder + calcium carbonate) 1m 3It is added in the range of 1.0 to 3.0 kg per unit. The fiber length of the polypropylene fiber is not limited, but for example, it should be 15 mm or less, preferably in the range of 10 to 12 mm. The fineness of the polypropylene fiber should be 35 decitex or less, preferably in the range of 25 to 35 decitex or 2 to 2.5 decitex. Here, decitex is the mass of 10,000 m of yarn in grams. Examples of such fibers that can be used include Balchip Pw·Jr (manufactured by Hagiwara Industries Co., Ltd.) and Daiwabo PZ (manufactured by Daiwabo Polytech Co., Ltd.).

[0011] According to this embodiment of concrete, since blast furnace slag, an industrial by-product, is used, the effective use of resources can be achieved, and the environmental burden can be reduced. Furthermore, if calcium carbonate produced by recovering CO2 from the atmosphere and exhaust gases is used, stable retention and storage of CO2 becomes possible, and therefore, a negative CO2 balance can be achieved. Furthermore, because it contains polypropylene fibers, it can suppress spalling when exposed to high temperatures. When a concrete member made of the concrete of this embodiment is exposed to high temperatures, such as during a fire, the polypropylene fibers melt and voids are formed within the concrete member. Therefore, these voids serve as escape routes for moisture (steam) that has evaporated from the concrete due to the high temperature. Thus, it is possible to suppress the rise in water vapor pressure inside the concrete member and suppress surface spalling. In this embodiment, the case in which polypropylene fibers are used as organic fibers is described, but the type of organic fiber is not limited. That is, any organic fiber that melts at high temperatures to form voids within the concrete member and serves as an escape route for moisture (steam) can be used to obtain the same effect. As for the organic fiber, it is sufficient if it is expected to be effective when melted at a high temperature of about 100 to 200°C, and vinylon or acrylic organic fibers may also be used. Since the slump flow value is maintained at 40 cm or more, the necessary fluidity for construction is ensured. If the concrete of this embodiment is used in a reinforced concrete building, it is possible to suppress spalling during a fire or the like and contribute to reducing carbon dioxide emissions. Further, by using the concrete of this embodiment, a wall member having fire resistance (for example, a curtain wall or a partition wall) can be constructed.

[0012] The experimental results carried out to confirm the workability and fire resistance of the concrete of this embodiment, which does not contain Portland cement and in which the proportion of calcium carbonate in the powder is within the range of 8.6 mass% to 45 mass%, are shown below. Table 1 shows the mixing table of the concrete used in the experiment. For the preparation A, the proportion of calcium carbonate in the powder was 45 mass%, for the preparation B, the proportion of calcium carbonate in the powder was 33 mass%, and for the preparation C, the proportion of calcium carbonate in the powder was 8.6 mass%.

[0013] The following materials were used in the experiment. Blast furnace slag BFS: Fine powder of blast furnace slag, density 2.89 g / cm 3 , Blaine specific surface area 4410 cm 2 / g, conforming to JIS A6206 Expansion material EX: Expansion material type 30 (lime-based expansion material), density 3.15 g / cm 3 , Blaine specific surface area 4040 cm 2 / g, conforming to JIS A6202 Hydrated lime CH: Special grade hydrated lime, density 2.20 g / cm 3 , Passing through a 600 μm sieve, conforming to JIS R9001 Light calcium carbonate Ac: Density 2.64 g / cm 3 , Blaine specific surface area 3560 cm 2 / g Heavy calcium carbonate LSP: Density 2.72 g / cm 3 , Blaine specific surface area 4850 cm 2 / g Fine aggregate S1: Mountain sand, produced in Ichihara City, Chiba Prefecture, surface dry density 2.60 g / cm 3 Fine aggregate S2: Crushed sand (limestone), produced in Toriigayama, Kochi Prefecture, surface dry density 2.67 g / cm 3 Coarse aggregate G: Crushed stone (limestone) from Garo, Hokkaido. Surface dry density 2.70 g / cm³ 3 Water W: Tap water Polypropylene fiber (PP): Density 0.91 g / cm³ 3 , 2.2dtex×10mm, moisture content 25%

[0014] [Table 1]

[0015] First, we will show the results of test mixing for concrete with polypropylene fibers added to each mix. The mixing was performed using a forced twin-shaft mixer with a nominal capacity of 55L. The amount used for the trial mix was 30L. The slump flow of the fresh concrete produced by the trial mix was measured in accordance with JIS A1150 "Slump Flow Test for Concrete," and the presence or absence of material segregation after the slump flow test was visually confirmed (separation of the paste was evaluated visually). Table 2 shows the results of the trial mixing.

[0016] [Table 2]

[0017] In Table 2, the separation resistance column is indicated as follows: "◎" if no separation was observed, "〇" if slight paste seepage was observed, and "△" if clear paste separation was observed. As shown in Table 2, the amount of polypropylene fiber that can be added to produce the paste without clear separation under the condition of a slump flow of 40 cm or more is 3.0 kg / m for formulation A. 3 Below, for mixture B, 3.0 kg / m 3 Below, for mixture C, 2.0 kg / m 3 The following is considered desirable.

[0018] Next, a heating test was conducted on a test specimen (100 mm in diameter x 200 mm in height) made from the concrete of this embodiment to check for the occurrence of spalling. In the experiment, three types of concrete mixes (mixes A, B, and C) were mixed with different amounts of polypropylene fibers (1 kg / m³) on the outside. 3 , 2kg / m 3 or 3 kg / m 3 Test specimens were prepared with the addition of ). Similar experiments were also conducted for comparative examples (Comparative Examples A-0, B-0, C-0) in which polypropylene fibers were not added to each formulation (Formulations A, B, C). Table 3 shows the amount of polypropylene fibers added to the test specimens. The heating test followed the heating curve for building fires (ISO 834), as shown in Figure 1, by heating the test specimen 2, placed on refractory bricks 3 inside furnace 1, from one side for 1 hour. Figure 2(a) shows the temperature inside furnace 1 for formulation A (ISO 834 heating curve and average furnace temperature during the heating test), Figure 2(b) shows the temperature inside furnace 1 for formulation B, and Figure 3 shows the temperature inside furnace 1 for formulation C. The concrete used to form the test specimens was mixed in 50L batches using a forced twin-shaft mixer with a nominal capacity of 55L.

[0019] [Table 3]

[0020] Figures 4-6 show the experimental results. Figure 4(a) is a photograph showing the heated specimens of Comparative Example A-0, Example A-2, and Example A-3, from left to right. Figure 4(b) is a photograph showing the heated specimens of Comparative Example B-0, Example B-2, and Example B-3, from left to right. Figure 4(c) is a photograph showing the heated specimens of Comparative Example C-0, Example C-1, and Example C-2, from left to right. Furthermore, Figure 4(a) is a graph showing the weight ratio before and after heating for Comparative Example A-0, Example A-2, and Example A-3, Figure 4(b) is a graph showing the weight ratio before and after heating for Comparative Example B-0, Example B-2, and Example B-3, and Figure 5 is a graph showing the weight ratio before and after heating for Comparative Example C-0, Example C-1, and Example C-2.

[0021] Regarding formulation A, as shown in Figure 4(a), spalling occurred in Comparative Example A-0, which did not contain polypropylene fibers, whereas spalling did not occur in Examples A-2 and A-3. Furthermore, as shown in Figure 5(a), in Examples A-2 and A-3, the weight of the specimens after heating was approximately 90% of the weight before heating, whereas in Comparative Example A-0, the concrete spalled due to spalling, resulting in a weight of slightly less than 60% of the weight before heating. Compared to formulation A, formulation B, which has a lower calcium carbonate content, showed spalling in comparative example B-0, which did not contain polypropylene fibers, as shown in Figure 4(b). In contrast, no spalling occurred in examples B-2 and B-3. Furthermore, as shown in Figure 5(b), the weight of the specimens after heating in examples B-2 and B-3 was approximately 90% of the weight before heating, whereas in comparative example B-0, the weight decreased to about 80% due to spalling and delamination of the concrete. For formulation C, which has a lower calcium carbonate content than formulations A and B, as shown in Figure 4(c), comparative example C-0, which did not contain added polypropylene fibers, experienced spalling, whereas examples C-1 and C-2 did not. Furthermore, as shown in Figure 6, in examples B-2 and B-3, the weight of the specimens after heating was approximately 90% of the weight before heating, whereas in comparative example B-0, the weight decreased to about 80% due to spalling and delamination of the concrete.

[0022] Therefore, a hydraulic composition comprising a binder containing at least one of blast furnace slag, an expansive agent, and slaked lime, and calcium carbonate, wherein the powder contains calcium carbonate in the range of 8.6% to 45% by mass and polypropylene fibers are added, preferably 1 m of powder 3 It was confirmed that adding polypropylene fibers in the range of 1.0 to 3.0 kg per unit ensures the resistance to material segregation and fluidity of fresh concrete, and also improves the fire resistance of the concrete member after hardening.

[0023] Here, Table 4 shows the results of compressive strength tests conducted on comparative examples A-0, B-0, and C-0 in accordance with JIS A1108 "Concrete Compressive Strength Test". For the compressive strength test, three specimens were prepared, and the compressive strength of each specimen was measured. The compressive strengths are shown in Table 4.

[0024] [Table 4]

[0025] As shown in Table 4, the compressive strength of the concrete in Comparative Example A-0 was 49.2 N / mm². 2 The compressive strength of the concrete in comparative example B-0 was 42.8 N / mm². 2 The compressive strength of the concrete in comparative example C-0 was 53.1 N / mm². 2 It is therefore quite practical.

[0026] Next, a heating test of a wall was conducted using the concrete of this embodiment. In this heating test, a square-shaped test specimen (small wall specimen 4) was subjected to the heating test to check for the occurrence of spalling. Figure 7 shows the small wall specimen 4. As shown in Figure 7, the small wall specimen 4 was formed to be 1300 mm wide x 1300 mm high x 150 mm thick, and vertical reinforcement bars 5 (D10@150) and horizontal reinforcement bars 6 (D10@200) were placed on the front and back sides. Table 5 shows the concrete mix.

[0027] The following materials were used in the experiment. Blast furnace slag BFS: Fine blast furnace slag powder, density 2.89 g / cm³ 3 Expansion agent EX: Expansion agent type 30 (lime-based expansion agent) Density 3.15 g / cm³ 3 Slaked lime CH: Slaked lime special edition, density 2.20g / cm 3 Light calcium carbonate (Ac): Density 2.56 g / cm³ 3 Fine aggregate S1: Mountain sand Surface dry density 2.60g / cm 3 Fine aggregate S2: Crushed sand (limestone) Surface dry density 2.66g / cm 3 Coarse aggregate G: Crushed stone (limestone) Surface dry density 2.69 g / cm³ 3 Water W: Tap water Polypropylene fiber (PP): Density 0.91 g / cm³ 3 2.2 dtex × 10 mm, moisture content 15.6% (measured value before experiment)

[0028] [Table 5]

[0029] In the experiment, two types of concrete mixes (mix A and B) were used. Mix A contained different amounts of polypropylene fiber (1 kg / m³) on the outside. 3 , 2kg / m 3 or 3 kg / m 3 ) was added, and three types of small wall test specimens 4 (Examples A-21, A-22, A-23) were prepared. On the other hand, for formulation B, polypropylene fibers were divided externally at 2 kg / m 3 By adding [the specified substance], one type of small wall test specimen 4 (Example B-21) was prepared.

[0030] First, the results of test mixing of the concrete for each example are shown. The slump flow of the fresh concrete produced by the trial mix was measured in accordance with JIS A1150 "Slump Flow Test for Concrete," and the presence or absence of material segregation after the slump flow test was visually confirmed (separation of the paste was evaluated visually). Table 6 shows the results of the trial mixing.

[0031] [Table 6]

[0032] The heating test followed the heating curve for building fires (ISO 834), and as shown in Figure 8, a small wall test specimen 4, positioned to shield the opening 7 of the furnace 1, was heated from one side for one hour. Figures 9 to 16 show the experimental results. Figure 9(a) shows the average temperature inside the furnace 1 in the heating test according to Example A-21, and (b) shows the relationship between the unheated surface temperature of the small wall test specimen 4 according to Example A-21 and time. Similarly, Figures 10, 11, and 12 show the relationship between the average temperature inside the furnace 1 and the unheated surface temperature of the small wall test specimen 4 and time in the heating tests according to Examples A-22, A-23, and B-22, respectively. In walls forming fire compartments (e.g., curtain walls and fire walls), there is a regulation regarding the maximum temperature on the unheated surface of the wall (heat shielding: the temperature must not rise by more than 140°C from the start of heating), but as shown in Figures 9(b) to 12(b), the heat shielding requirement was satisfied in all examples.

[0033] Figure 13(a) is a photograph of the small wall test specimen 4 of Example A-21 before heating, and (b) is a photograph of the small wall test specimen 4 of Example A-21 after heating. Similarly, Figure 14 shows photographs of the small wall test specimen 4 of Example A-22, Figure 15 shows photographs of the small wall test specimen 4 of Example A-23, and Figure 16 shows photographs of the small wall test specimen 4 of Example B-22 before and after heating. As shown in Figures 13 to 16, no spalling or peeling that penetrated the wall occurred in any of the small wall test specimens 4. Therefore, it was confirmed that by using the concrete of this embodiment, it is possible to construct wall members with fire-resistant properties (for example, curtain walls and partition walls).

[0034] Here, Table 7 shows the results of compressive strength tests conducted in accordance with JIS A1108 "Concrete Compressive Strength Test" for Examples A-21, A-22, A-23, and B-22. For the compressive strength test, three specimens were prepared from the concrete of each of the examples A-21, A-22, A-23, and B-22, and the compressive strength of each specimen was measured.

[0035] [Table 7]

[0036] As shown in Table 7, the compressive strength of the concrete in Example A-21 is 49.5 N / mm². 2 The compressive strength of the concrete in Example A-22 is 50.4 N / mm². 2 The compressive strength of the concrete in Example A-23 is 43.7 N / mm². 2 The compressive strength of the concrete in Example B-22 is 27.1 N / mm². 2 This ensures the strength required for use as a wall component.

[0037] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention. [Explanation of Symbols]

[0038] 1 furnace 2 Specimen 3 Firebrick 4. Small wall test specimens 5. Vertical lines 6 horizontal lines 7 Opening

Claims

1. A hydraulic composition comprising powder, organic fibers, and water, The aforementioned powder consists of a binder and calcium carbonate. The binder does not contain Portland cement and contains at least one of blast furnace slag, an expansive agent, and slaked lime. The proportion of calcium carbonate in the powder is within the range of 8.6% by mass to 45% by mass. A hydraulic composition characterized in that the organic fibers are added in an amount of 1.0 kg to 3.0 kg per 1 m³ of the powder.

2. The hydraulic composition according to claim 1, characterized in that the calcium carbonate is light calcium carbonate.

3. The hydraulic composition according to claim 1 or claim 2, characterized in that the proportion of calcium carbonate is in the range of 33% by mass to 45% by mass.

4. The hydraulic composition according to claim 1, characterized in that the slump flow value measured in accordance with JIS A 1150 is 40 cm or more.

5. A wall member characterized by being formed from a hardened body of the hydraulic composition described in claim 1.

6. The wall member according to claim 5, characterized in that the wall thickness is 150 mm or more.

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