Method for producing concrete and method for adjusting fluidity of flowable composition

Abstract

To provide a method for producing concrete using a flowable composition that is excellent in workability and does not contain heavy calcium carbonate, and to provide a method for adjusting fluidity of a flowable composition.SOLUTION: This invention relates to a method for producing concrete by curing a flowable composition containing water, cement, and light calcium carbonate, wherein: the cement contained in the flowable composition has a Blaine specific surface area of 2500 cm2 / g or more and 3050 cm2 / g or less; and the light calcium carbonate contained in the flowable composition has an average particle diameter R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of 15000 cm2 / g or more and 85000 cm2 / g or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing concrete and a method for adjusting the fluidity of a fluid composition. [Background technology]

[0002] The cement used in concrete emits large amounts of carbon dioxide (CO2) during manufacturing due to the decarbonation of raw materials and the fuel used during firing. In response to growing interest in curbing climate change in recent years, there is a need to significantly reduce carbon dioxide emissions during concrete manufacturing. This type of concrete is also required to be as easy to work as conventional concrete.

[0003] For example, Patent Document 1 describes concrete containing an aqueous slurry of heavy calcium carbonate with an average particle size of 0.5 to 3 μm, which is produced by wet-pulverizing limestone, for the purpose of improving workability.

[0004] In the concrete of Patent Document 1, heavy calcium carbonate is used as an essential component to increase the fluidity of the concrete and improve workability. However, there is a demand for concrete that has excellent workability without using heavy calcium carbonate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-128612 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a method for producing concrete using a fluid composition which has excellent workability and does not contain heavy calcium carbonate, and a method for adjusting the fluidity of a fluid composition. [Means for solving the problem]

[0007] [1] A method for producing concrete by hardening a fluid composition containing water, cement, and precipitated calcium carbonate, wherein the cement contained in the fluid composition has a Blaine specific surface area of ​​2500 cm 2 / g or more 3050cm 2 / g or less, and the precipitated calcium carbonate contained in the flowable composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15000 cm 2 / g or more 85000cm 2 A method for producing concrete in which the viscosity is less than or equal to 1 / g. [2] The precipitated calcium carbonate contained in the fluid composition has a Blaine specific surface area of ​​2900 cm 2 / g or more 7500cm 2 / g or less. [3] The method for producing concrete according to the above [1] or [2], wherein the ratio (R2 / R1) of the average particle size R2 of the precipitated calcium carbonate contained in the flowable composition to the average particle size R1 of the cement contained in the flowable composition is 1.0 or more and 4.5 or less. [4] The method for producing concrete according to any one of the above [1] to [3], wherein the precipitated calcium carbonate is precipitated calcium carbonate. [5] The flowable composition further contains ground granulated blast furnace slag, and the ground granulated blast furnace slag contained in the flowable composition has a Blaine specific surface area of ​​2750 cm 2 / g or more 5000cm 2 The method for producing concrete according to any one of the above [1] to [4], wherein the viscosity is 0.05 to 0.5 μm, and the viscosity is 0.5 μm or less. [6] The method for producing concrete according to any one of the above [1] to [5], wherein the flowable composition further contains ground granulated blast furnace slag, and the ratio (R2 / R3) of the average particle size R2 of the light calcium carbonate contained in the flowable composition to the average particle size R3 of the ground granulated blast furnace slag contained in the flowable composition is 1.0 or more and 4.5 or less. [7] A method for adjusting the fluidity of a fluid composition containing water, cement, and precipitated calcium carbonate, comprising: 2 / g or more 3050cm 2 / g or less, and cement having an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15000 cm 2 / g or more 85000cm 2 / g or less, to increase the fluidity of the flowable composition. [8] A method for producing concrete by hardening a fluid composition containing water, cement, precipitated calcium carbonate, and ground granulated blast furnace slag, wherein the precipitated calcium carbonate contained in the fluid composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15,000 cm 2 / g or more 85000cm 2 / g or less, and the ground granulated blast furnace slag contained in the flowable composition has a Blaine specific surface area of ​​2750 cm 2 / g or more 5000cm 2 A method for producing concrete in which the viscosity is less than or equal to 1 / g. [9] The cement contained in the flowable composition has a Blaine specific surface area of ​​2400 cm 2 / g or more 3150cm 2 / g or less.

[10] The precipitated calcium carbonate contained in the flowable composition has a Blaine specific surface area of ​​2900 cm 2 / g or more 7500cm 2 / g or less.

[11] A method for producing concrete according to any one of the above [8] to

[10] , wherein the ratio (R2 / R3) of the average particle size R2 of the light calcium carbonate contained in the flowable composition to the average particle size R3 of the ground granulated blast furnace slag contained in the flowable composition is 1.0 or more and 4.5 or less.

[12] The method for producing concrete according to any one of the above [8] to

[11] , wherein the ratio (R2 / R1) of the average particle size R2 of the precipitated calcium carbonate contained in the flowable composition to the average particle size R1 of the cement contained in the flowable composition is 1.0 or more and 4.5 or less.

[13] The method for producing concrete according to any one of the above [8] to

[12] , wherein the precipitated calcium carbonate is precipitated calcium carbonate.

[14] A method for adjusting the fluidity of a fluid composition containing water, cement, precipitated calcium carbonate, and ground granulated blast furnace slag, the method comprising: 2 / g or more 85000cm 2 / g or less and a Blaine specific surface area of ​​2750 cm 2 / g or more 5000cm 2 A method for adjusting the fluidity of a flowable composition, comprising mixing a ground granulated blast furnace slag having a viscosity of 1000 saturates or less with a granulated blast furnace slag having a viscosity of 1000 saturates or less and increasing the fluidity of the flowable composition. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for producing concrete using a flowable composition that has excellent workability and does not contain heavy calcium carbonate, and a method for adjusting the flowability of a flowable composition. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a detailed description will be given based on an embodiment.

[0010] The present inventors have focused on precipitated calcium carbonate, which is calcium carbonate produced by a chemical reaction. In response to the recent demand for reducing carbon dioxide emissions, they have investigated the production of concrete using precipitated calcium carbonate obtained by bringing carbon dioxide into contact with waste liquid containing Ca ions derived from concrete or the like.

[0011] However, it was found that when light calcium carbonate was used as an admixture, the fluidity of the flowable composition was significantly reduced, resulting in a significant deterioration in workability. The reason for this was found to be that, although light calcium carbonate and heavy calcium carbonate are both calcium carbonate, they have a large difference in BET specific surface area, resulting in light calcium carbonate having significantly more uneven particle surfaces and internal voids than heavy calcium carbonate.

[0012] First, the fluidity of the flowable composition before concrete hardening is more affected by the amount of free water than by the amount of bound water. That is, even if the unit water amount of the flowable composition is the same, if the amount of bound water is large, the amount of free water will relatively decrease, and the fluidity of the flowable composition will decrease. In other words, even if the unit water amount of the flowable composition is the same, if the amount of bound water is small, the amount of free water will relatively increase, and the fluidity of the flowable composition will improve.

[0013] Because bound water is physically and chemically adsorbed to the surface and internal voids of particles, it is significantly affected by the surface area (specific surface area) and internal structure of the particles. For example, if the same amount of particles are contained in a flowable composition, a smaller particle size will increase the specific surface area of ​​the particles and increase the amount of bound water. Furthermore, particles with many voids in their internal structure will also increase the amount of bound water. As a result, fluidity decreases. On the other hand, if the same amount of particles are contained in a flowable composition, a larger particle size will decrease the specific surface area of ​​the particles and decrease the amount of bound water. Furthermore, particles with few voids in their internal structure, such as cement and heavy calcium carbonate, will also decrease the amount of bound water. As a result, fluidity improves.

[0014] Bound water, which is physically and chemically adsorbed water, is also affected by the reactivity of the particles with water. If the particle is highly reactive with water, such as cement, there will be more bound water, and if the particle is less reactive, such as ground granulated blast furnace slag, there will be less bound water.

[0015] Furthermore, an investigation into the differences between light calcium carbonate and heavy calcium carbonate revealed that although the densities of both were similar, the light calcium carbonate, which had a median diameter four to five times larger than that of heavy calcium carbonate, had a BET specific surface area six times larger than that of heavy calcium carbonate. This indicates that light calcium carbonate has more internal voids and more bound water than heavy calcium carbonate.

[0016] Based on these findings, namely, the differences in the surface shape and internal structure between light calcium carbonate and heavy calcium carbonate, and the influence of free water and bound water on the fluidity of concrete, the researchers conducted research and found that concrete with excellent workability can be produced by using cement or ground granulated blast furnace slag with a smaller Blaine specific surface area than usual in combination with light calcium carbonate with a large BET specific surface area. The present invention was completed based on these findings.

[0017] (First embodiment) In the method for producing concrete according to the first embodiment, concrete is produced by hardening a fluid composition containing water, cement, and precipitated calcium carbonate. The cement contained in the fluid composition has a Blaine specific surface area of ​​2500 cm 2 / g or more 3050cm 2 / g or less, and the precipitated calcium carbonate contained in the flowable composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15000 cm 2 / g or more 85000cm 2 / g or less.

[0018] The flowable composition used in the concrete manufacturing method of the first embodiment contains water, cement, and light calcium carbonate as essential components. The flowable composition does not contain heavy calcium carbonate. The flowable composition, which is a cement composition, hardens over time. In this manner, concrete can be manufactured.

[0019] The cement constituting the flowable composition is preferably Portland cement. Portland cement includes ordinary Portland cement (OPC), as well as types such as high-early-strength, ultra-high-early-strength, moderate-heat, low-heat, and sulfate-resistant, which are specified in JIS R 5210:2019. The flowable composition can be made by blending one or more of these various Portland cements. Among these, it is preferable to use one or two of ordinary Portland cement and high-early-strength Portland cement.

[0020] The cement contained in the flowable composition has a Blaine specific surface area of ​​2500 cm 2 / g or more 3050cm 2 / g or less. The above range of Blaine specific surface area of ​​cement is smaller than the Blaine specific surface area of ​​ordinary cement that is included in general fluid compositions and is used for the purpose of improving fluidity. When the Blaine specific surface area of ​​cement is 2500 cm 2 / g or more, the flowable composition does not suffer from poor hardening and good workability can be obtained. 2 When the Blaine specific surface area of ​​the cement is 2500 cm / g or less, good workability of the fluid composition can be obtained even when light calcium carbonate is used. 2 / g or more, preferably 2600 cm 2 / g or more, more preferably 2700 cm 2 / g or more. The upper limit of the Blaine specific surface area of ​​cement is 3050 cm 2 / g or less, and preferably 2900 cm 2 / g or less, more preferably 2800 cm 2 / g or less.

[0021] The light calcium carbonate contained in the flowable composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less. When the light calcium carbonate has an average particle size R2 of 10.0 μm or more, it is possible to easily produce a flowable composition having a desired composition, for example, by preventing the powder from floating in the air during production of the flowable composition. Furthermore, when the light calcium carbonate has an average particle size R2 of 30.0 μm or less, it can be handled as a powder material without any problems, like other powder materials contained in the flowable composition. From this perspective, the lower limit of the average particle size R2 of the light calcium carbonate is 10.0 μm or more. Furthermore, the upper limit of the average particle size R2 of the light calcium carbonate is 30.0 μm or less, preferably 20.0 μm or less, and more preferably 15.0 μm or less.

[0022] The BET specific surface area of ​​the precipitated calcium carbonate contained in the flowable composition is 15,000 cm 2 / g or more 85000cm 2 / g or less. The BET specific surface area of ​​the precipitated calcium carbonate is 15,000 cm 2 / g or more, light calcium carbonate can be easily produced without a consolidation treatment. In addition, the light calcium carbonate has a BET specific surface area of ​​85,000 cm 2 When the BET specific surface area of ​​the precipitated calcium carbonate is 15,000 cm / g or less, the amount of bound water is not excessively large, and the flowable composition can have good flowability, thereby improving the workability of the flowable composition. 2 / g or more, preferably 25000 cm 2 / g or more, more preferably 35,000 cm 2 / g or more. The upper limit of the BET specific surface area of ​​precipitated calcium carbonate is 85,000 cm 2 / g or less, preferably 75000 cm 2 / g or less, more preferably 65000 cm 2 / g or less.

[0023] The BET specific surface area of ​​the precipitated calcium carbonate is measured in accordance with JIS Z 8830, a method for measuring the specific surface area of ​​powders (solids) by gas adsorption.

[0024] The upper limit of the Blaine specific surface area of ​​the precipitated calcium carbonate contained in the flowable composition is preferably 7500 cm 2 / g or less, more preferably 4000 cm 2 / g or less, more preferably 3600 cm 2 / g or less, and the smaller the Blaine specific surface area, the better. 2 When the Blaine specific surface area of ​​the precipitated calcium carbonate contained in the flowable composition is 2900 cm or less, the amount of bound water can be further prevented from becoming excessive, and therefore, the flowability of the flowable composition can be further prevented from decreasing. 2 / g or more. The Blaine specific surface area of ​​the precipitated calcium carbonate is 2900 cm 2 When the specific surface area is 1 / g or more, the Blaine specific surface area is equivalent to that of other powder materials, and the decrease in fluidity of the flowable composition due to the influence of the surface shape of the particles can be further suppressed.

[0025] Furthermore, the lower limit of the ratio (R2 / R1) of the average particle size R2 of the precipitated calcium carbonate contained in the flowable composition to the average particle size R1 of the cement contained in the flowable composition is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. When the ratio (R2 / R1) is 1.0 or more, the particle size of the precipitated calcium carbonate does not become excessively small, and the precipitated calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0026] The upper limit of the ratio (R2 / R1) is preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.0 or less. When the ratio (R2 / R1) is 4.5 or less, the particle size of the precipitated calcium carbonate does not become excessively large, and the precipitated calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0027] The precipitated calcium carbonate is preferably precipitated calcium carbonate obtained by crystallization. Among them, precipitated calcium carbonate obtained by bringing carbon dioxide into contact with waste liquid containing Ca ions derived from concrete or the like is preferred. Since precipitated calcium carbonate obtained by crystallization using carbon dioxide as a raw material is used, the method for producing concrete of this embodiment can significantly reduce carbon dioxide.

[0028] Furthermore, as long as workability is not impaired, the flowable composition may further contain ground granulated blast furnace slag, aggregate (fine aggregate, coarse aggregate), etc., depending on the desired properties of the concrete and flowable composition.

[0029] The ground granulated blast furnace slag contained in the flowable composition is a fine powder specified in JIS A 6206:2013, "Ground granulated blast furnace slag for concrete." Granulated blast furnace slag is produced in a blast furnace by rapidly cooling molten blast furnace slag, which is produced simultaneously with shear iron, with water or air. Its basicity is 1.60 or higher. Ground granulated blast furnace slag is produced by drying and pulverizing this granulated blast furnace slag, or by adding gypsum to it. By replacing part of the Portland cement with ground granulated blast furnace slag, it is possible to reduce carbon dioxide emissions during the cement manufacturing process.

[0030] The types of ground granulated blast furnace slag are classified by specific surface area (cm 2 There are four types depending on the molecular weight (g), and any of them may be used in the present invention. a) Blast furnace slag powder 3000: specific surface area is 2750 or more and less than 3500 b) Blast furnace slag powder 4000: specific surface area is 3500 or more and less than 5000 c) Blast furnace slag powder 6000: specific surface area is 5000 or more and less than 7000 d) Blast furnace slag powder 8000: specific surface area is 7000 or more but less than 10000

[0031] In order to further improve the workability of the flowable composition, the Blaine specific surface area of ​​the ground granulated blast furnace slag contained in the flowable composition is set to 2750 cm 2 / g or more 5000cm 2 The above range of the Blaine specific surface area of ​​the ground granulated blast furnace slag is smaller than the Blaine specific surface area of ​​ordinary ground granulated blast furnace slag that is contained in a general fluid composition and used for the purpose of improving fluidity.

[0032] The Blaine specific surface areas of cement, light calcium carbonate and ground granulated blast furnace slag are measured in accordance with the specific surface area test specified in JIS R 5201 Physical Testing Methods for Cement.

[0033] Furthermore, the lower limit of the ratio (R2 / R3) of the average particle size R2 of the light calcium carbonate contained in the flowable composition to the average particle size R3 of the ground granulated blast furnace slag contained in the flowable composition is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. When the ratio (R2 / R3) is 1.0 or more, the particle size of the light calcium carbonate does not become excessively small, and the light calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0034] The upper limit of the ratio (R2 / R3) is preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.0 or less. When the ratio (R2 / R3) is 4.5 or less, the particle size of the precipitated calcium carbonate does not become excessively large, and the precipitated calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0035] The fine aggregate contained in the flowable composition is an aggregate defined in JIS A 5308, JIS A 5005, JIS A 5002, and JIS A 5011. Examples of fine aggregate include crushed sand, sand, river sand, sea sand, crushed lime sand, recycled aggregate, lightweight aggregate, and heavy aggregate.

[0036] The coarse aggregate contained in the flowable composition is an aggregate defined in JIS A 5308, JIS A 5005, JIS A 5002, and JIS A 5011, and is distinguished from the above-mentioned fine aggregate by particle size, and is classified by whether or not it passes through a 5 mm sieve. In practice, fine aggregate is defined as aggregate that passes entirely through a 10 mm sieve and 85% or more by weight passes through a 5 mm sieve, and coarse aggregate is defined as aggregate that retains 85% or more by weight on a 5 mm sieve.

[0037] The flowable composition is hardened to produce concrete. For example, the flowable composition is filled into a formwork and hardened to a predetermined shape. The flowable composition can be cast in place as well as precast concrete.

[0038] The concrete produced by the concrete production method of this embodiment may be used as is for use in remaining formwork, etc., or may be shaped, processed, etc. as needed and then used for specific purposes. The concrete can be used for applications such as cast-in-place reinforced concrete, high-slump concrete, zero-slump concrete, and prestressed concrete.

[0039] The method for adjusting the fluidity of a flowable composition according to the first embodiment is a method for adjusting the fluidity of a flowable composition containing water, cement, and precipitated calcium carbonate. 2 / g or more 3050cm 2 / g or less, and cement having an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15000 cm 2 / g or more 85000cm 2 / g or less of precipitated calcium carbonate to increase the fluidity of the flowable composition.

[0040] The flowable composition whose fluidity is adjusted by the method for adjusting the fluidity of a flowable composition of this embodiment is the flowable composition used in the method for producing concrete of this embodiment described above. Therefore, it is preferable that the components and composition of the flowable composition whose fluidity is adjusted by the method for adjusting the fluidity are the same as the components and composition of the flowable composition used in the method for producing concrete.

[0041] The method for adjusting the fluidity of a flowable composition according to the present embodiment allows the fluidity of the flowable composition to be controlled. Therefore, a method for producing concrete using a flowable composition with controlled fluidity has excellent workability.

[0042] According to the first embodiment described above, by setting the specific surface areas of the cement and precipitated calcium carbonate constituting the flowable composition and the particle size of the precipitated calcium carbonate within predetermined ranges, the flowability of the flowable composition can be easily controlled, and further, concrete with excellent workability can be produced using the flowable composition with controlled fluidity.

[0043] (Second embodiment) The second embodiment of the concrete manufacturing method is basically the same as the first embodiment of the concrete manufacturing method, except that the fluid composition used in the second embodiment contains, in addition to water, cement, and precipitated calcium carbonate, ground granulated blast furnace slag as an essential component. Therefore, the different components will be mainly described here. Note that in the following embodiments, descriptions that overlap with those of the first embodiment will be omitted or simplified.

[0044] The method for producing concrete according to the second embodiment involves hardening a flowable composition containing water, cement, precipitated calcium carbonate, and ground granulated blast furnace slag to produce concrete. The precipitated calcium carbonate contained in the flowable composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less, and a BET specific surface area of ​​15,000 cm. 2 / g or more 85000cm 2 / g or less, and the ground granulated blast furnace slag contained in the flowable composition has a Blaine specific surface area of ​​2750 cm 2 / g or more 5000cm2 / g or less.

[0045] The flowable composition used in the concrete manufacturing method of the second embodiment contains water, cement, light calcium carbonate, and ground granulated blast furnace slag as essential components. The flowable composition does not contain heavy calcium carbonate. The flowable composition, which is a cement composition, hardens over time. In this manner, concrete can be manufactured.

[0046] The light calcium carbonate contained in the flowable composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less. When the light calcium carbonate has an average particle size R2 of 10.0 μm or more, it is possible to easily produce a flowable composition having a desired composition, for example, by preventing the powder from floating in the air during production of the flowable composition. Furthermore, when the light calcium carbonate has an average particle size R2 of 30.0 μm or less, it can be handled as a powder material without any problems, like other powder materials contained in the flowable composition. From this perspective, the lower limit of the average particle size R2 of the light calcium carbonate is 10.0 μm or more. Furthermore, the upper limit of the average particle size R2 of the light calcium carbonate is 30.0 μm or less, preferably 20.0 μm or less, and more preferably 15.0 μm or less.

[0047] The BET specific surface area of ​​the precipitated calcium carbonate contained in the flowable composition is 15,000 cm 2 / g or more 85000cm 2 / g or less. The BET specific surface area of ​​the precipitated calcium carbonate is 15,000 cm 2 / g or more, light calcium carbonate can be easily produced without a consolidation treatment. In addition, the light calcium carbonate has a BET specific surface area of ​​85,000 cm 2 When the BET specific surface area of ​​the precipitated calcium carbonate is 15,000 cm / g or less, the amount of bound water is not excessively large, and the flowable composition can have good flowability, thereby improving the workability of the flowable composition. 2 / g or more, preferably 25000 cm 2 / g or more, more preferably 35,000 cm 2 / g or more. The upper limit of the BET specific surface area of ​​precipitated calcium carbonate is 85,000 cm 2 / g or less, preferably 75000 cm 2 / g or less, more preferably 65000 cm 2 / g or less.

[0048] The ground granulated blast furnace slag contained in the fluid composition has a Blaine specific surface area of ​​2750 cm 2 / g or more 5000cm 2 / g or less. The above range of the Blaine specific surface area of ​​the ground granulated blast furnace slag is smaller than the Blaine specific surface area of ​​ordinary ground granulated blast furnace slag that is included in general flowable compositions and used for the purpose of improving flowability. When the Blaine specific surface area of ​​the ground granulated blast furnace slag is within the above range, the workability of the flowable composition can be improved.

[0049] The lower limit of the Blaine specific surface area of ​​the cement contained in the flowable composition is preferably 2400 cm 2 / g or more, more preferably 2600 cm 2 / g or more, more preferably 2700 cm 2 / g or more. The Blaine specific surface area of ​​the cement is 2400 cm 2 When the Blaine specific surface area is 3150 cm / g or more, the flowable composition does not suffer from poor hardening and has better workability. 2 / g or less, more preferably 2900 cm 2 / g or less, more preferably 2800 cm 2 / g or less. The Blaine specific surface area of ​​the cement is 3150 cm 2 When the Blaine specific surface area is 0.05g / g or less, better workability of the flowable composition can be obtained even when light calcium carbonate is used. The Blaine specific surface area of ​​the cement in the above range is smaller than the Blaine specific surface area of ​​ordinary cements that are included in general flowable compositions and are used for the purpose of improving flowability.

[0050] The upper limit of the Blaine specific surface area of ​​the precipitated calcium carbonate contained in the flowable composition is preferably 7500 cm2 / g or less, more preferably 4000 cm 2 / g or less, more preferably 3600 cm 2 / g or less, and the smaller the Blaine specific surface area, the better. 2 When the Blaine specific surface area of ​​the precipitated calcium carbonate contained in the flowable composition is 2900 cm or less, the amount of bound water can be further prevented from becoming excessive, and therefore, the flowability of the flowable composition can be further prevented from decreasing. 2 / g or more. The Blaine specific surface area of ​​the precipitated calcium carbonate is 2900 cm 2 When the specific surface area is 1 / g or more, the Blaine specific surface area is equivalent to that of other powder materials, and the decrease in fluidity of the flowable composition due to the influence of the surface shape of the particles can be further suppressed.

[0051] Furthermore, the lower limit of the ratio (R2 / R3) of the average particle size R2 of the light calcium carbonate contained in the flowable composition to the average particle size R3 of the ground granulated blast furnace slag contained in the flowable composition is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. When the ratio (R2 / R3) is 1.0 or more, the particle size of the light calcium carbonate does not become excessively small, and the light calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0052] The upper limit of the ratio (R2 / R3) is preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.0 or less. When the ratio (R2 / R3) is 4.5 or less, the particle size of the precipitated calcium carbonate does not become excessively large, and the precipitated calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0053] Furthermore, the lower limit of the ratio (R2 / R1) of the average particle size R2 of the precipitated calcium carbonate contained in the flowable composition to the average particle size R1 of the cement contained in the flowable composition is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more. When the ratio (R2 / R1) is 1.0 or more, the particle size of the precipitated calcium carbonate does not become excessively small, and the precipitated calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0054] The upper limit of the ratio (R2 / R1) is preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.0 or less. When the ratio (R2 / R1) is 4.5 or less, the particle size of the precipitated calcium carbonate does not become excessively large, and the precipitated calcium carbonate can be uniformly dispersed during mixing, thereby further improving the fluidity and workability of the flowable composition.

[0055] The precipitated calcium carbonate is preferably precipitated calcium carbonate obtained by crystallization. Among them, precipitated calcium carbonate obtained by bringing carbon dioxide into contact with waste liquid containing Ca ions derived from concrete or the like is preferred. Since precipitated calcium carbonate obtained by crystallization using carbon dioxide as a raw material is used, the method for producing concrete of this embodiment can significantly reduce carbon dioxide.

[0056] Furthermore, the flowable composition may further contain aggregate (fine aggregate, coarse aggregate) and the like depending on the desired properties of the concrete or flowable composition, provided that workability is not reduced.

[0057] The method for adjusting the fluidity of a flowable composition according to the second embodiment is a method for adjusting the fluidity of a flowable composition containing water, cement, precipitated calcium carbonate, and ground granulated blast furnace slag. In this method, the flowability of a flowable composition is adjusted by mixing water, cement, and ground granulated blast furnace slag having an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15,000 cm. 2 / g or more 85000cm 2 / g or less and a Blaine specific surface area of ​​2750 cm2 / g or more 5000cm 2 The fluidity of the flowable composition is increased by mixing the flowable composition with ground granulated blast furnace slag having a viscosity of 1000 MPa or less.

[0058] The method for adjusting the fluidity of a flowable composition according to the present embodiment allows the fluidity of the flowable composition to be controlled. Therefore, a method for producing concrete using a flowable composition with controlled fluidity has excellent workability.

[0059] According to the second embodiment described above, the flowable composition contains, as essential components, water, cement, light calcium carbonate, and ground granulated blast furnace slag. By setting the specific surface areas of the light calcium carbonate and ground granulated blast furnace slag constituting the flowable composition, and the particle size of the light calcium carbonate, within predetermined ranges, the flowability of the flowable composition can be easily controlled, and furthermore, concrete with excellent workability can be produced using the flowable composition with controlled fluidity.

[0060] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure. [Example]

[0061] Next, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0062] (Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-4) Cement compositions were prepared according to the compositions shown in Table 1. Immediately after preparation, the fluidity of the cement compositions was evaluated. The cement compositions according to the compositions shown in Table 1 were then poured into a cylindrical formwork measuring 10 cm in diameter and 20 cm in height, and cured in an underwater environment at 20°C for 28 days. A hydraulically hardened body was thus obtained.

[0063] (Examples 2-1 to 2-6) The fluidity of the cement composition was evaluated and a hydraulic hardened body was obtained in the same manner as in Example 1-1, except that the cement composition having the composition shown in Table 1 was changed to the cement composition having the composition shown in Table 2.

[0064] In Tables 1 and 2, W is water, OPC is ordinary Portland cement, LWCC is light calcium carbonate, S is fine aggregate, G is coarse aggregate, and BFS is ground granulated blast furnace slag. The units for W, OPC (N), LWCC (LC), S, G, and BFS (B) are kg / m 3 W / (N+LC) is the mass part of water per 100 mass parts of the total amount of cement and precipitated calcium carbonate. The properties of each material are as follows:

[0065] OPC: Density 3.16g / cm 3 LWCC: Density 2.30g / cm 3 S: Density 2.64g / cm 3 G: Density 2.65g / cm 3 BFS: Density 2.91g / cm 3

[0066] [Table 1]

[0067] [Table 2]

[0068] The hydraulically hardened bodies obtained from the cement compositions of the above Examples and Comparative Examples were subjected to the following measurements and evaluations. The results are shown in Tables 3 and 4.

[0069] [1] Slump flow Measurements were made in accordance with JIS A 1150:2020 "Test Method for Slump Flow of Concrete." Measurements were made immediately after mixing the cement composition, and the difference (S2-S1) between the slump flow (S1) of Comparative Example 1-1 (Reference), which corresponds to a typical concrete, and the slump flow (S2) of the Example or Comparative Example was evaluated. Slump was evaluated as "good" when the absolute value of the difference in slump flow (S2-S1) was 5 cm or less, and as "bad" when the difference in slump flow was greater than 5 cm.

[0070] [Table 3]

[0071] [Table 4]

[0072] As shown in Tables 1 to 4, in Examples 1-1 to 1-6, the cement compositions contained water, cement, and light calcium carbonate as essential components. The specific surface areas of the cement and light calcium carbonate, as well as the particle size of the light calcium carbonate, were set within predetermined ranges, thereby enabling the compositions to have good fresh properties even when containing light calcium carbonate. In addition, in Examples 2-1 to 2-6, the cement compositions contained water, cement, light calcium carbonate, and ground granulated blast furnace slag as essential components. The specific surface areas of the light calcium carbonate and ground granulated blast furnace slag, as well as the particle size of the light calcium carbonate, were set within predetermined ranges, enabling the compositions to have good fresh properties even when containing light calcium carbonate. On the other hand, in Comparative Examples 1-2 to 1-4, the specific surface areas of the cement and light calcium carbonate, and the particle size of the light calcium carbonate were not set within the predetermined ranges, and therefore the fresh properties of the cement compositions were poor.

Claims

1. A method for producing concrete by hardening a fluid composition containing water, cement, and precipitated calcium carbonate, comprising: The cement contained in the flowable composition has a Blaine specific surface area of ​​2500 cm ２ / g or more 3050cm ２ / g or less, The precipitated calcium carbonate contained in the flowable composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15,000 cm ２ / g or more 85000cm ２ / g or less, Concrete manufacturing method.

2. The precipitated calcium carbonate contained in the flowable composition has a Blaine specific surface area of ​​2900 cm ２ / g or more 7500cm ２ 2. The method for producing concrete according to claim 1, wherein the viscosity of the concrete is 1 / g or less.

3. 2. The method for producing concrete according to claim 1, wherein a ratio (R2 / R1) of an average particle size R2 of the precipitated calcium carbonate contained in the flowable composition to an average particle size R1 of the cement contained in the flowable composition is 1.0 or more and 4.5 or less.

4. 2. The method for producing concrete according to claim 1, wherein the precipitated calcium carbonate is precipitated calcium carbonate.

5. The flowable composition further contains ground granulated blast furnace slag, and the ground granulated blast furnace slag contained in the flowable composition has a Blaine specific surface area of ​​2750 cm ２ / g or more 5000cm ２ The method for producing concrete according to any one of claims 1 to 4, wherein the concrete has a viscosity of 1 / 2 g or less.

6. 5. The method for producing concrete according to claim 1, wherein the flowable composition further contains ground granulated blast furnace slag, and a ratio (R2 / R3) of an average particle size R2 of the light calcium carbonate contained in the flowable composition to an average particle size R3 of the ground granulated blast furnace slag contained in the flowable composition is 1.0 or more and 4.5 or less.

7. A method for adjusting fluidity of a fluid composition containing water, cement, and precipitated calcium carbonate, comprising the steps of: Water and a Blaine specific surface area of ​​2500 cm ２ / g or more 3050cm ２ / g or less, and a cement having an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15000 cm ２ / g or more 85000cm ２ / g or less, and light calcium carbonate, thereby increasing the fluidity of the flowable composition.

8. A method for producing concrete by hardening a fluid composition containing water, cement, precipitated calcium carbonate, and ground granulated blast furnace slag, comprising: The precipitated calcium carbonate contained in the flowable composition has an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15,000 cm ２ / g or more 85000cm ２ / g or less, The ground granulated blast furnace slag contained in the flowable composition has a Blaine specific surface area of ​​2750 cm ２ / g or more 5000cm ２ / g or less, Concrete manufacturing method.

9. The cement contained in the flowable composition has a Blaine specific surface area of ​​2400 cm ２ / g or more 3150cm ２ The method for producing concrete according to claim 8, wherein the viscosity of the concrete is 1 / g or less.

10. The precipitated calcium carbonate contained in the flowable composition has a Blaine specific surface area of ​​2900 cm ２ / g or more 7500cm ２ The method for producing concrete according to claim 8, wherein the viscosity of the concrete is 1 / g or less.

11. 9. The method for producing concrete according to claim 8, wherein a ratio (R2 / R3) of an average particle size R2 of the precipitated calcium carbonate contained in the flowable composition to an average particle size R3 of the ground granulated blast furnace slag contained in the flowable composition is 1.0 or more and 4.5 or less.

12. 9. The method for producing concrete according to claim 8, wherein a ratio (R2 / R1) of an average particle size R2 of the precipitated calcium carbonate contained in the flowable composition to an average particle size R1 of the cement contained in the flowable composition is 1.0 or more and 4.5 or less.

13. The method for producing concrete according to any one of claims 8 to 12, wherein the precipitated calcium carbonate is precipitated calcium carbonate.

14. A method for adjusting fluidity of a fluid composition containing water, cement, precipitated calcium carbonate, and ground granulated blast furnace slag, comprising: Water, cement, and a mixture of water and cement having an average particle size R2 of 10.0 μm or more and 30.0 μm or less and a BET specific surface area of ​​15000 cm ２ / g or more 85000cm ２ / g or less and a light calcium carbonate having a Blaine specific surface area of ​​2750 cm ２ / g or more 5000cm ２ / g or less of ground granulated blast furnace slag to increase the fluidity of the flowable composition.

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