Hydraulic components, and hardened substances

Abstract

The objective is to provide a hydraulic composition and a hardened body that contain calcium carbonate, yet possess high strength and excellent workability. [Solution] The hydraulic composition according to the present invention contains blast furnace slag fine powder, calcium carbonate, and an irritant, wherein the water-to-powder ratio is 10.0% or more and 40.0% or less, and when the water-to-powder ratio is greater than 25.0% and 40.0% or less, the proportion of calcium carbonate in the powder is 38.0% by mass or less, and when the water-to-powder ratio is 10.0% or more and 25.0% or less, the proportion of calcium carbonate in the powder is 20.0% by mass or less.

Description

[Technical Field]

[0001] The present invention relates to a hydraulic composition containing calcium carbonate and a hardened body. [Background technology]

[0002] As part of CCU (Carbon dioxide Capture and Utilization) technology, research and development is actively underway on the production of calcium carbonate, which is mineralized by reacting CO2 in exhaust gases with calcium from waste and by-products. In order to promote CO2 reduction through the sustainable production of this calcium carbonate, securing its uses is essential, and it is expected to be used in large quantities as a material for mortar and concrete. Furthermore, the applicant of this application has proposed in Patent Document 1 a hydraulic composition to which a large amount (30-95% by mass) of calcium carbonate has been added. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2021 / 256484 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The inventors of this invention conducted thorough research on hydraulic compositions containing calcium carbonate and identified the following problems. It was found that a high calcium carbonate content in the hydraulic composition makes it difficult to increase the binder content, thus hindering the achievement of high strength. As a result, the compressive strength of the hardened body made from the hydraulic composition becomes low (for example, 30 N / mm²). 2 (Below a certain age), the range of applicable products was limited. Furthermore, it was found that a high calcium carbonate content in the hydraulic composition leads to increased viscosity, reducing workability and making manufacturing difficult.

[0005] Therefore, an object of the present invention is to provide a hydraulic composition that contains calcium carbonate and yet has high strength and excellent workability, as well as a cured body.

Means for Solving the Problems

[0006] As a result of studying the calcium carbonate content of the hydraulic composition, the inventors of the present invention have found that high strength and excellent workability can be achieved simultaneously by setting the calcium carbonate content to a predetermined value or less, and have thus created the present invention.

[0007] The above problems can be solved by the following means. The hydraulic composition according to the present invention contains blast furnace slag fine powder, calcium carbonate, and an activator, and has a water-to-powder ratio of 10.0% or more and 40.0% or less. When the water-to-powder ratio exceeds 25.0% and is 40.0% or less, the proportion of the calcium carbonate in the powder is 38.0% by mass or less. When the water-to-powder ratio is 10.0% or more and 25.0% or less, the proportion of the calcium carbonate in the powder is 20.0% by mass or less. According to the present invention, since the proportion of calcium carbonate in the powder is a predetermined value or less, it can exhibit high strength and excellent workability. In the hydraulic composition according to the present invention, the activator is preferably at least one selected from the group consisting of slaked lime, quicklime, lime-based expansive materials, calcium sulfoaluminate-based expansive materials, and Portland cement, and the content of the activator is preferably 15 parts by mass or more and 19 parts by mass or less with respect to 100 parts by mass of the blast furnace slag fine powder. Further, in the hydraulic composition according to the present invention, the calcium carbonate is preferably light calcium carbonate. The cured body according to the present invention is composed of the above-described hydraulic composition. According to the present invention, since the cured body is composed of the above-described hydraulic composition, it can exhibit high strength and excellent workability.

Effects of the Invention

[0008] The hydraulic composition and the hardened body according to the present invention are high-strength and excellent in workability.

Brief Description of the Drawings

[0009] [Figure 1] It is a graph showing the results of the 500 mm flow reaching time of Samples 1-1 to 1-7 (ordinary strength series) and Samples 2-1 to 2-5 (high strength series). [Figure 2A] It is a graph showing the results of the compressive strength of Samples 1-1 to 1-7 (ordinary strength series). [Figure 2B] It is a graph showing the results of the compressive strength of Samples 2-1 to 2-5 (high strength series).

Modes for Carrying Out the Invention

[0010] Hereinafter, modes (embodiments) for implementing the hydraulic composition and the hardened body according to the present invention will be described. [Hydraulic Composition] The hydraulic composition according to the present embodiment is a hydraulic composition containing blast furnace slag fine powder, calcium carbonate, and an activator, and having a water-to-powder ratio within a predetermined range. And the activator is preferably at least one selected from the group consisting of slaked lime, quicklime, lime-based expansion material, calcium sulfoaluminate-based expansion material, and Portland cement. Hereinafter, each component constituting the hydraulic composition according to the present embodiment will be described in detail.

[0011] (Water-to-Powder Ratio) The water-to-powder ratio is the content ratio of water and powder in the hydraulic composition. Specifically, it is a value calculated by "[content of water (kg / m 3 ) / content of powder (kg / m [[ID=3"]] 3 ) × 100". And the water-to-powder ratio of the hydraulic composition according to the present embodiment is 10.0% or more and 40.0% or less. Note that the water contained in the hydraulic composition is not particularly limited, and tap water, groundwater, sludge water, etc. can be used.

[0012] (Fine powder of blast furnace slag) The fine powder of blast furnace slag is either the one obtained by drying and pulverizing the granulated blast furnace slag or the one obtained by adding gypsum thereto, and is defined in JIS A6206:2013. When the content of the fine powder of blast furnace slag in the hydraulic composition exceeds 25.0% and is 40.0% or less in the water-to-powder ratio, for example, 250 kg / m 3 or more, 300 kg / m 3 or more, 330 kg / m 3 or more, and 450 kg / m 3 or less, 400 kg / m 3 or less, 350 kg / m 3 or less. When the content of the fine powder of blast furnace slag in the hydraulic composition is 10.0% or more and 25.0% or less in the water-to-powder ratio, for example, 450 kg / m 3 or more, 500 kg / m 3 or more, 550 kg / m 3 or more, and 650 kg / m 3 or less, 600 kg / m 3 or less, 560 kg / m 3 or less.

[0013] (Calcium carbonate) Calcium carbonate (CaCO3) includes heavy calcium carbonate (also called natural calcium carbonate) produced by pulverizing and classifying limestone, and light calcium carbonate (also called synthetic calcium carbonate) produced by synthesis, and light calcium carbonate is preferred. The inventors have found that by setting the ratio of calcium carbonate in the powder to a predetermined value or less, it is possible to achieve both high strength and excellent workability while reducing the CO2 emissions based on the use of calcium carbonate. The inventors have also confirmed that the preferable upper limit value of this ratio of calcium carbonate varies depending on the value of the water-to-powder ratio.

[0014] (Calcium carbonate: when the water-to-powder ratio exceeds 25.0% and is 40.0% or less) If the water-to-powder ratio exceeds 25.0% but is 40.0% or less, the percentage of calcium carbonate in the powder (= calcium carbonate content (kg / m³)) 3 ) / Powder content (kg / m³ 3 The ratio of calcium carbonate (x100) is preferably 38.0% by mass or less, and more preferably 35.0% by mass or less, 30.0% by mass or less, 28.0% by mass or less, and 25.0% by mass or less. By keeping the proportion of calcium carbonate below a predetermined value, it is possible to achieve both high strength and excellent workability. Furthermore, when the water-to-powder ratio is within the aforementioned range, the proportion of calcium carbonate in the powder is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and more preferably 5.0% by mass or more. By having a calcium carbonate proportion above a predetermined value, the CO2 emission reduction effect based on the use of calcium carbonate can be greatly increased. Furthermore, when the water-to-powder ratio is within the aforementioned range, the calcium carbonate content in the hydraulic composition is, for example, 10 kg / m³. 3 More than 15kg / m 3 More than 21kg / m 3 That is all, 180 kg / m 3 Below 175kg / m 3 Below, 169kg / m 3 The following applies:

[0015] (Calcium carbonate: When the water-to-powder ratio is between 10.0% and 25.0%) When the water-to-powder ratio is between 10.0% and 25.0%, the proportion of calcium carbonate in the powder is preferably 20.0% by mass or less, more preferably 18.0% by mass or less, and more preferably 15.0% by mass or less. By keeping the proportion of calcium carbonate below a predetermined value, it is possible to achieve both high strength and excellent workability. Furthermore, when the water-to-powder ratio is within the aforementioned range, the proportion of calcium carbonate in the powder is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and more preferably 5.0% by mass or more. By having a calcium carbonate proportion above a predetermined value, the CO2 emission reduction effect based on the use of calcium carbonate can be greatly increased. Furthermore, when the water-to-powder ratio is within the aforementioned range, the calcium carbonate content in the hydraulic composition is, for example, 25 kg / m³. 3 More than 30kg / m 3 More than 34kg / m 3 That is all, 170 kg / m 3 Below, 165kg / m 3 Below 160kg / m 3 The following applies:

[0016] (Stimulant) The stimulant is a substance that provides stimulation to accelerate hardening, and is preferably one or more selected from the group consisting of slaked lime, quicklime, lime-based expansives, calcium sulfoaluminate-based expansives, and Portland cement. These stimulants promote the hydration reaction of blast furnace slag fine powder, causing it to harden. The calcium ions leached from each stimulant have the effect of promoting the precipitation of calcium hydroxide in the blast furnace slag fine powder reaction stimulant and in the hardened body. Among stimulants, those that are water-soluble and release calcium ions quickly include slaked lime and quicklime. Those that are water-insoluble and release calcium ions slowly include expansive agents and Portland cement. It is even more preferable to use two or more types of stimulants with relatively different calcium ion release rates.

[0017] Slaked lime is defined in JIS R9001:2006. Since quicklime turns into slaked lime when it comes into contact with water, quicklime as specified in JIS R9001:2006 can be used 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. Expansion agents are defined in JIS A6202:2017 and mainly consist of lime-based expansion agents containing CaO and CaSO4, and calcium sulfoaluminate-based expansion agents containing CaO, C3A·CaSO4, and CaSO4. Portland cement refers to the type specified in JIS R5210:2019, including ordinary Portland cement, moderate-heat Portland cement, low-heat Portland cement, rapid-hardening Portland cement, ultra-rapid-hardening Portland cement, and sulfate-resistant Portland cement. In addition, cements with adjusted mineral compositions may be used as needed.

[0018] The stimulant content per 100 parts by mass of blast furnace slag fine powder is preferably 15 parts by mass or more, and preferably 19 parts by mass or less. By keeping the stimulant content within a predetermined range, the desired effect (achieving both high strength and excellent workability) can be more reliably realized.

[0019] (Fine aggregate) Fine aggregate refers to aggregate that passes completely through a 10mm mesh sieve and passes through a 5mm mesh sieve by more than 85% of its mass, in accordance with JIS A5308 Annex A. The content of fine aggregate in the hydraulic composition is not particularly limited, but for example, 400 kg / m 3 More than 500kg / m 3 More than 600kg / m 3 That is all, 1000 kg / m 3 Below 900kg / m 3 Below 800kg / m 3 The following applies:

[0020] (coarse aggregate) Coarse aggregate refers to aggregate that remains on a 5mm mesh sieve by 85% or more by mass, and conforms to Annex A of JIS A5308. The coarse aggregate content in the hydraulic composition is not particularly limited, but for example, 600 kg / m³ 3 More than 700kg / m 3 More than 800kg / m 3 That is all, 1200 kg / m 3 Below 1100kg / m 3 Below 1000kg / m 3 The following applies:

[0021] (Other materials) The hydraulic composition according to this embodiment may appropriately contain conventionally known materials (e.g., chemical admixtures) used in general concrete and mortar, as long as the desired effects of the present invention are not hindered. Examples of chemical admixtures include AE ​​agents, high-performance water-reducing agents, curing accelerators, water-reducing agents, AE water-reducing agents, high-performance AE water-reducing agents, and fluidizing agents, as specified in JIS A6204:2011.

[0022] [Cured body] The cured body according to this embodiment is a cured member (a member after construction) made of the hydraulic composition described above. Furthermore, since the cured body according to this embodiment consists of a hydraulic composition with the above-mentioned component composition, it is possible to achieve both high strength and excellent workability while reducing CO2 emissions based on the use of calcium carbonate.

[0023] [Method for producing a hydraulic composition, and method for producing a hardened body] The method for producing the hydraulic composition according to this embodiment includes the step of preparing each of the materials described above. The method for producing the hardened body according to this embodiment includes the steps of mixing, casting, curing, etc., after the above steps. Furthermore, the processing in each step should be carried out under the same conditions as those used to manufacture general concrete or mortar compositions or hardened materials. [Examples]

[0024] (Composition) Table 1 shows the formulations of each sample (hydraulic composition) used in the examples. Table 2 shows the details of each material incorporated into each sample. In Table 1, "P" represents the powder (BFS+Ex+CH+CC in Table 1), and "B" represents the binder (BFS+Ex+CH in Table 1). Also, "P×%" for the admixture in Table 1 refers to the ratio (percentage) to the mass of the powder.

[0025] [Table 1]

[0026] [Table 2]

[0027] (Test content: Slump flow test) The slump flow test was conducted in accordance with JIS A1150:2020 "Test Method for Slump Flow of Concrete," and the time (seconds) to reach a 500 mm flow was measured. The slump flow test was performed by adjusting the amount of admixture (high-performance AE water-reducing agent, AE agent) added so that the target slump flow and air content were within the range shown in Table 1. Table 3 and Figure 1 show the results of the slump flow test.

[0028] (Test content: Visual inspection) For the visual inspection, the testers visually checked the properties of each sample during the slump flow test, including whether or not material segregation occurred, the flow of the concrete, and handling, which is important for the workability of the concrete. Table 3 shows the results of the visual inspection.

[0029] (Evaluation criteria: Viscosity (workability)) For samples 1-1 to 1-7, which are part of the standard strength series, the viscosity (workability) was evaluated as "○ (excellent)" if the time to reach a 500mm flow was 15 seconds or less and the result of the visual test indicated that it was usable in the field. It was evaluated as "△ (somewhat good)" if the time to reach a 500mm flow was 15 seconds or less and the result of the visual test indicated that it was usable in the field but close to its limit. In all other cases, it was evaluated as "× (not good)". For the high-strength series samples 2-1 to 2-5, the viscosity (workability) was evaluated as "○ (excellent)" if the time to reach a 500mm flow was 20 seconds or less and the result of the visual test indicated that it was usable in the field; it was evaluated as "△ (somewhat good)" if the time to reach a 500mm flow was 20 seconds or less and the result of the visual test indicated that it was usable in the field but close to its limit; and it was evaluated as "× (not good)" in all other cases.

[0030] (Test content: Compression strength test) For the compressive strength test specimens, the samples listed in Table 1 were mixed together (admixtures were added to ensure that the target slump flow and air volume were within the ranges shown in Table 1), and then poured into a mold (inner diameter 10 mm, height 20 mm, cylindrical). Subsequently, samples from the standard strength series were cured underwater for 7 and 14 days to prepare test specimens. Samples from the high strength series were steam-cured (held at 50°C for 3 hours), and thereafter, they were cured at ambient temperature for 1, 7, and 14 days to prepare test specimens. Then, a compressive strength test was performed on each of the prepared test specimens in accordance with JIS A1108:2018. Table 3 and Figures 2A and 2B show the results of the compressive strength test.

[0031] (Evaluation criteria: intensity expression) For samples 1-1 to 1-7, which are part of the standard strength series, the compressive strength at 7 days of age is 28 N / mm². 2 Furthermore, the compressive strength at 14 days of age is 30 N / mm². 2 If the results were as described above, the "strength development" was evaluated as "○ (high strength)," and otherwise, it was evaluated as "× (not high strength)." For the high-strength series, samples 2-1 to 2-5 have a compressive strength of 35 N / mm² at 1 day of age. 2 Furthermore, the compressive strength at 7 days of age is 40 N / mm². 2 If the results were as described above, the "strength development" was evaluated as "○ (high strength)," and otherwise, it was evaluated as "× (not high strength)."

[0032] [Table 3]

[0033] (Discussion of the results) Table 3 and Figure 1 show the results regarding "viscosity (workability)". Additionally, Table 3 and Figures 2A and 2B show the results regarding "strength development (strength)". Note that the dotted lines, dashed lines, and double-dotted lines in each figure represent approximate straight lines for each data set.

[0034] (Discussion of results: Standard strength series) Samples 1-1 to 1-7 are part of the normal strength series, with a water-to-powder ratio exceeding 25.0% and being 40.0% or less. However, it was confirmed that samples 1-1 to 1-7, in which the proportion of calcium carbonate in the powder (CC / P(%) in the table) is 38.0% by mass or less, achieve both excellent workability and high strength. Although the proportion of calcium carbonate in the powder for samples 1-7 was 38.0% by mass or less, it was slightly higher than average, resulting in a "△" rating for workability.

[0035] (Discussion of results: High-intensity series) Samples 2-1 to 2-5 are a high-strength series with a water-to-powder ratio of 10.0% to 25.0%. However, samples 2-1 to 2-4, in which the proportion of calcium carbonate in the powder (CC / P(%) in the table) is 20.0% by mass or less, were confirmed to achieve both excellent workability and high strength. On the other hand, sample 2-5 had a higher proportion of calcium carbonate in the powder than 20.0% by mass, resulting in poor workability.

[0036] (Discussion of results: Summary) From the results above, it was found that, according to the present invention, it is possible to reduce CO2 emissions based on the use of calcium carbonate while simultaneously achieving excellent workability and high strength, making it possible to perform normal pouring as cast-in-place concrete and expanding the range of applicable products.

Claims

1. It contains blast furnace slag fine powder, calcium carbonate, and an irritant. The water-to-powder ratio is between 10.0% and 40.0%. When the water-to-powder ratio exceeds 25.0% and is 40.0% or less, the proportion of calcium carbonate in the powder is 38.0% by mass or less. A hydraulic composition characterized in that, when the water-to-powder ratio is 10.0% or more and 25.0% or less, the proportion of calcium carbonate in the powder is 20.0% by mass or less.

2. The stimulant is one or more selected from the group consisting of slaked lime, quicklime, lime-based expansives, calcium sulfoaluminate-based expansives, and Portland cement. The hydraulic composition according to claim 1, characterized in that the content of the stimulant is 15 parts by mass or more and 19 parts by mass or less per 100 parts by mass of the blast furnace slag fine powder.

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

4. A cured body comprising the hydraulic composition according to any one of claims 1 to 3.

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