Ground granulated blast furnace slag and its manufacturing method

Abstract

To provide a blast furnace slag fine powder having a large activity index even though having a low basicity (specifically, 1.40 to 1.70) and a Blaine specific surface area which is not excessively large (specifically, 3,000 to 5,500 cm2 / g) and capable of being suitably used as a cement admixture.SOLUTION: A blast furnace slag fine powder has a 5% volume cumulative particle diameter of 1.60 μm or less, a 10% volume cumulative particle diameter of 2.20 μm or less, a Blaine specific surface area of 3,000 to 5,500 cm2 / g, and a basicity of 1.40 to 1.70 defined as "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)".SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to ground granulated blast furnace slag and a method for producing the same. [Background technology]

[0002] In the cement industry, ground granulated blast furnace slag, which is a by-product of the production of pig iron in a blast furnace, has traditionally been used as a cement admixture. Basicity is one of the indicators of the quality of ground granulated blast furnace slag as a cement admixture, and it is known that the higher the basicity, the higher the activity. The basicity of ground granulated blast furnace slag used in Japan as a cement admixture is usually 1.8 or more. It is said that blast furnace slag with low basicity is difficult to use as a cement admixture, and most of it is used as civil engineering materials such as roadbed materials after crushing. Regarding the basicity of ground granulated blast furnace slag for concrete, "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" stipulates that granulated blast furnace slag with a basicity of 1.60 or more should be used.

[0003] As a raw material for blast furnace cement, slag powder that can suppress the decrease in strength is described in Reference 1 as having a Blaine specific surface area of ​​4,000 to 7,000 cm. 2 / g, and the 24 μm sieve residue measured by a laser diffraction particle size distribution measurement method is 30 vol % or less. In addition, as a ground granulated blast furnace slag having good strength development and excellent fluidity, cited reference 2 describes a ground granulated blast furnace slag having a particle size of 1.0 to 5.0 μm at a cumulative volume fraction of 50% and a total pore volume of 0.02 cm 3 / g or less. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-109906 A [Patent Document 2] JP 2018-127375 A Summary of the Invention [Problem to be solved by the invention]

[0005] Increasing the fineness of ground granulated blast furnace slag is known as a technique for increasing the activity of ground granulated blast furnace slag. In this regard, "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" specifies four types of ground granulated blast furnace slag with different Blaine specific surface areas, and the activity index of these ground granulated blast furnace slag increases as the Blaine specific surface area increases. However, increasing the Blaine specific surface area increases the cost of pulverization. The object of the present invention is to produce a sintered cellulose having a low basicity (specifically, 1.40 to 1.70) and a not excessively large Blaine specific surface area (specifically, 3,000 to 5,500 cm 2 The object of the present invention is to provide a ground granulated blast furnace slag which has a large activity index despite its low molecular weight (Mg), and can be suitably used as a cement admixture. [Means for solving the problem]

[0006] As a result of intensive research into solving the above problems, the present inventors have discovered a method for producing a 5% volume cumulative particle size of 1.60 μm or less, a 10% volume cumulative particle size of 2.20 μm or less, and a Blaine specific surface area of ​​3,000 to 5,500 cm 2 The present inventors have found that the above object can be achieved by using ground granulated blast furnace slag having a molecular weight of 1.40 to 1.70 / g and a basicity of 1.40 to 1.70, and have thus completed the present invention. That is, the present invention provides the following [1] to [4]. [1] 5% volume cumulative particle size is 1.60μm or less, 10% volume cumulative particle size is 2.20μm or less, and Blaine specific surface area is 3,000~5,500cm 2 / g, and a basicity as defined in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" of 1.40 to 1.70. [2] The ground granulated blast furnace slag described in [1] above, in which the activity index and flow value ratio values ​​specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" are 75% or more at 28 days, 95% or more at 91 days, and 95% or more at 91 days. [3] A cement composition comprising the ground granulated blast furnace slag according to [1] or [2] above, cement clinker powder, and gypsum powder. [4] A method for producing ground granulated blast furnace slag according to [1] or [2] above, comprising: a blast furnace slag selection step of checking whether or not blast furnace slag to be used as a material for the ground granulated blast furnace slag satisfies the condition that the basicity of the blast furnace slag is within the range of 1.40 to 1.70 as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" and selecting the blast furnace slag as a material for the ground granulated blast furnace slag if the blast furnace slag satisfies the condition; and selecting the blast furnace slag selected in the blast furnace slag selection step from a blast furnace slag having a 5% volume cumulative particle size of 1.60 μm or less, a 10% volume cumulative particle size of 2.20 μm or less, and a Blaine specific surface area of ​​3,000 to 5,500 cm. 2 pulverizing the slag using a pulverizing means so that the slag has a molecular weight of 1.0 to 1.5 kg / g to obtain ground granulated blast furnace slag. Effect of the Invention

[0007] The ground granulated blast furnace slag of the present invention has a low basicity (specifically, 1.40 to 1.70) and a not excessively large Blaine specific surface area (specifically, 3,000 to 5,500 cm 2 / g), it has a large activity index and can be suitably used as a cement admixture. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The ground granulated blast furnace slag of the present invention has a 5% volume cumulative particle size of 1.60 μm or less, a 10% volume cumulative particle size of 2.20 μm or less, and a Blaine specific surface area of ​​3,000 to 5,500 cm 2 / g, and the basicity as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" is 1.40 to 1.70. The details are explained below. The basicity specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" can be calculated using the following formula (1). Basicity = [(CaO + MgO + Al 2 O 3 ) / SiO 2 〕 ···(1) (In formula (1), CaO, MgO, Al 2 O 3 and SiO 2 are the amounts of CaO, MgO, and Al in the ground granulated blast furnace slag, respectively. 2 O 3 and SiO 2 The content (mass%) of

[0009] The basicity of the ground granulated blast furnace slag of the present invention, represented by the above formula (1), is 1.40 or more, preferably 1.42 or more, more preferably 1.44 or more, even more preferably 1.45 or more, and particularly preferably 1.48 or more, from the viewpoint of easy availability and increasing the activity index. Moreover, from the viewpoint of effectively utilizing ground granulated blast furnace slag having a low basicity, the basicity is 1.70 or less, preferably 1.65 or less, more preferably 1.63 or less, even more preferably less than 1.60, even more preferably 1.55 or less, and particularly preferably 1.50 or less. The ground granulated blast furnace slag having a basicity of more than 1.70 has a sufficiently large activity index even without adjustment of the particle size distribution, etc.

[0010] The 5% volume cumulative particle size of the ground granulated blast furnace slag is 1.60 μm or less, preferably 1.55 μm or less, more preferably 1.50 μm or less, even more preferably 1.45 μm or less, and particularly preferably 1.40 μm or less. If the 5% volume cumulative particle size exceeds 1.60 μm, the activity index of the ground granulated blast furnace slag becomes small, making it difficult to use the ground granulated blast furnace slag as a cement admixture. In addition, from the viewpoint of improving the flow value ratio and reducing the cost of pulverization, the 5% volume cumulative particle size is preferably 1.20 μm or more, more preferably 1.25 μm or more, and particularly preferably 1.30 μm or more. In this specification, the term "5% cumulative particle size by volume" refers to the particle size at 5% of the volume cumulative distribution obtained by measuring the particle size of particles using a laser diffraction scattering particle size distribution measuring device or the like and accumulating the particle sizes from smallest to largest based on the measured particle size. The same applies to "10% cumulative particle size by volume", "50% cumulative particle size by volume", and "90% cumulative particle size by volume". The 10% volume cumulative particle size of the ground granulated blast furnace slag is 2.20 μm or less, preferably 2.15 μm or less, more preferably 2.10 μm or less, even more preferably 2.05 μm or less, and particularly preferably 2.00 μm or less. If the 10% volume cumulative particle size exceeds 2.20 μm, the activity index of the ground granulated blast furnace slag becomes small, making it difficult to use the ground granulated blast furnace slag as a cement admixture. In addition, from the viewpoint of improving the flow value ratio and reducing the cost of pulverization, the 10% volume cumulative particle size is preferably 1.70 μm or more, more preferably 1.75 μm or more, and particularly preferably 1.80 μm or more.

[0011] The 50% volume cumulative particle size of the ground granulated blast furnace slag is preferably 10.0 μm or less, more preferably 9.5 μm or less, and particularly preferably 9.0 μm or less, from the viewpoint of increasing the activity index of the ground granulated blast furnace slag. Also, the 50% volume cumulative particle size is preferably 4.0 μm or more, more preferably 4.5 μm or more, and particularly preferably 5.0 μm or more, from the viewpoint of improving the flow value ratio and reducing the cost of pulverization. The 90% volume cumulative particle size of the ground granulated blast furnace slag is preferably 40.0 μm or less, more preferably 38.0 μm or less, and particularly preferably 36.0 μm or less, from the viewpoint of increasing the activity index of the ground granulated blast furnace slag. Also, the 90% volume cumulative particle size is preferably 10.0 μm or more, more preferably 15.0 μm or more, and particularly preferably 18.0 μm or more, from the viewpoint of improving the flow value ratio and reducing the cost of pulverization.

[0012] The Blaine specific surface area of ​​ground granulated blast furnace slag is 3,000 to 5,500 cm 2 / g, preferably 3,100 to 5,300 cm 2 / g, more preferably 3,300 to 5,000 cm 2 / g, and more preferably 3,500 to 4,500 cm 2 / g, and particularly preferably 3,600 to 4,000 cm 2 / g. The above Blaine specific surface area is 3,000 cm 2 If the Blaine specific surface area is less than 5,500 cm / g, the activity index of the ground granulated blast furnace slag will be small. In addition, when the ground granulated blast furnace slag is used as a cement admixture, the strength development of a cement composition containing the cement admixture will be reduced. 2 If the powder exceeds 1 / g, the flow ratio decreases and the cost of grinding increases. In this specification, the term "Blaine specific surface area" refers to a surface area measured by the method specified in "7.3 Specific surface area" of "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)".

[0013] The 28-day activity index of the blast furnace slag fine powder, determined by the method specified in "7.4 Activity index and flow value ratio" of "JIS A 6206:2013 (Blast furnace slag fine powder for concrete)", is preferably 75% or more, more preferably 78% or more, still more preferably 80% or more, and particularly preferably 85% or more. If the 28-day activity index is 75% or more, the strength development property of the cement composition using the blast furnace slag fine powder as a cement admixture can be further improved, so it can be more suitably used as a cement admixture. The upper limit value of the 28-day activity index is not particularly limited, but is usually 110% (generally 105%). The 91-day activity index of the blast furnace slag fine powder, determined by the method specified in "7.4 Activity index and flow value ratio" of "JIS A 6206:2013 (Blast furnace slag fine powder for concrete)", is preferably 95% or more, more preferably 98% or more, still more preferably 100% or more, and particularly preferably 105% or more. If the 91-day activity index is 95% or more, the strength development property of the cement composition using the blast furnace slag fine powder as a cement admixture can be further improved, so it can be more suitably used as a cement admixture. The upper limit value of the 91-day activity index is not particularly limited, but is usually 120% (generally 110%).

[0014] The flow value ratio of the blast furnace slag fine powder, determined by the method specified in "7.4 Activity index and flow value ratio" of "JIS A 6206:2013 (Blast furnace slag fine powder for concrete)", is preferably 95% or more, more preferably 96% or more, still more preferably 98% or more, and particularly preferably 100% or more. If the flow value ratio is 95% or more, the fluidity of the cement composition using the blast furnace slag fine powder as a cement admixture can be further improved, so it can be more suitably used as a cement admixture. The upper limit value of the flow value ratio is not particularly limited, but is usually 120% (generally 110%).

[0015] The cement composition of the present invention contains the above-mentioned ground granulated blast furnace slag, cement clinker powder, and gypsum powder. The cement clinker is not particularly limited, and examples thereof include various Portland cement clinkers such as normal Portland cement clinker, high-early-strength Portland cement clinker, moderate-heat Portland cement clinker, low-heat Portland cement clinker, and sulfate-resistant Portland cement clinker, ecocement clinker, etc. These may be used alone or in combination of two or more. Among these, ordinary Portland cement clinker is preferred from the viewpoint of strength development of the cement composition. The gypsum is not particularly limited, and examples thereof include anhydrous gypsum, dihydrate gypsum, hemihydrate gypsum, etc. These may be used alone or in combination of two or more.

[0016] The cement composition may contain other materials as required. Examples of other materials that may be contained as required include fine aggregate, coarse aggregate, water, various admixtures such as air-entraining agents, water-reducing agents, air-entraining water-reducing agents, high-performance water-reducing agents, and high-performance air-entraining water-reducing agents, and various cement admixtures (admixtures) such as fly ash and silica fume.

[0017] The proportion of ground granulated blast furnace slag in 100% by mass of the cement composition is preferably 1-70% by mass, more preferably 4-60% by mass, and particularly preferably 8-50% by mass. If the proportion is 1% by mass or more, the effective use of ground granulated blast furnace slag can be further promoted. If the proportion is 70% by mass or less, the decrease in the strength development of the cement composition can be prevented.

[0018] The method for producing the cement composition of the present invention is not particularly limited, and examples thereof include (i) a method of simultaneously mixing cement clinker powder, ground granulated blast furnace slag, and gypsum powder, (ii) a method of mixing cement (a mixture of cement clinker powder and gypsum powder) and ground granulated blast furnace slag, and (iii) a method of mixing cement (a mixture of cement clinker powder and gypsum powder) and a mixture of ground granulated blast furnace slag and gypsum powder. In the method (iii), the mixture of ground granulated blast furnace slag and gypsum powder may be a mixture obtained by mixing ground granulated blast furnace slag and gypsum powder, or a mixture obtained by simultaneously grinding blast furnace slag and gypsum. In addition, when water is mixed in the method for producing a cement composition, the water may be mixed with a mixture of ground granulated blast furnace slag, cement clinker powder, and gypsum powder, or the cement (a mixture of cement clinker powder and gypsum powder), water, and ground granulated blast furnace slag may be mixed simultaneously.

[0019] One example of a method for producing the ground granulated blast furnace slag of the present invention includes a blast furnace slag selection step in which blast furnace slag to be used as a material for the ground granulated blast furnace slag of the present invention is examined to see whether it satisfies the condition that the basicity is within the range of 1.40 to 1.70 as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" and, if the blast furnace slag satisfies the above condition, the blast furnace slag selected in the blast furnace slag selection step is selected as a material for the ground granulated blast furnace slag of the present invention; 2 and a blast furnace slag crushing step of crushing the blast furnace slag by a crushing means so as to obtain a ground granulated blast furnace slag of about 1 / g. Each step will be explained in detail below.

[0020] [Blast furnace slag selection process] This process is a process in which the blast furnace slag to be determined whether or not to be used as a material for the ground granulated blast furnace slag of the present invention is examined to see whether it satisfies the condition that the basicity is within the range of 1.40 to 1.70 as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)", and if the blast furnace slag satisfies the above condition, the blast furnace slag is selected as a material for the ground granulated blast furnace slag of the present invention. In this step, the blast furnace slag to be judged is not particularly limited, and examples thereof include granulated blast furnace slag obtained by quenching with water and crushing molten slag produced as a by-product when producing pig iron in a blast furnace. The blast furnace slag may be in the form of a lump or a powder.

[0021] In this process, the numerical range of basicity, which is the above condition, may be appropriately changed taking into consideration the desired activity index of the ground granulated blast furnace slag and the effective utilization of the blast furnace slag. For example, from the viewpoint of ease of availability and increasing the activity index of the target ground granulated blast furnace slag, the lower limit of the numerical range of basicity may be set to preferably 1.42, more preferably 1.44, even more preferably 1.45, and particularly preferably 1.48. Also, from the viewpoint of effectively utilizing ground granulated blast furnace slag having a low basicity, the upper limit of the numerical range of basicity may be set to preferably 1.65, more preferably 1.63, even more preferably 1.60, even more preferably 1.55, and particularly preferably 1.50.

[0022] When the basicity of the blast furnace slag satisfies the above conditions, the blast furnace slag is pulverized in the blast furnace slag pulverization process described later. When the blast furnace slag does not satisfy the above conditions, it is not pulverized in the blast furnace slag pulverization process described later, but is used for other purposes or pulverized by other pulverization methods. For example, when the basicity of the blast furnace slag exceeds 1.70, even if the blast furnace slag is not pulverized in the blast furnace slag pulverization process described later so that the numerical values ​​of the 5% volume cumulative particle size of the obtained blast furnace slag ground powder are within a specific numerical range, a blast furnace slag ground powder having a sufficiently large activity index can be obtained, and then, after being pulverized by a general pulverization method, it can be used as a blast furnace slag ground powder for cement admixtures. In addition, it is difficult to obtain a blast furnace slag having a basicity of less than 1.40.

[0023] [Blast furnace slag crushing process] In this process, the blast furnace slag selected in the blast furnace slag selection process is sieved to have a 5% volume cumulative particle size of 1.60 μm or less, a 10% volume cumulative particle size of 2.20 μm or less, and a Blaine specific surface area of ​​3,000 to 5,500 cm. 2 This is a blast furnace slag crushing process in which the blast furnace slag is crushed by a crushing means so that the blast furnace slag has a particle size of 1 / g, thereby obtaining ground granulated blast furnace slag. In addition, the blast furnace slag and gypsum in an amount equivalent to at least a portion of the gypsum powder contained in the cement composition may be simultaneously ground in this step. The numerical ranges of the 5% volume cumulative particle size, 10% volume cumulative particle size, Blaine specific surface area, etc. of the ground granulated blast furnace slag obtained by pulverizing the above-mentioned blast furnace slag may be appropriately changed in consideration of the activity index, flow value, etc. of the target ground granulated blast furnace slag. The numerical ranges of the above-mentioned 5% volume cumulative particle size, 10% volume cumulative particle size, Blaine specific surface area, etc. are the same as the numerical ranges of the 5% volume cumulative particle size, 10% volume cumulative particle size, Blaine specific surface area, etc. of the ground granulated blast furnace slag of the present invention described above.

[0024] The grinding means is not particularly limited, and known grinders and the like can be used. Examples of grinding means include ball mills, vertical roller mills, disk mills, and jet mills. Only one of these may be used, or two or more may be used in combination. The grinding means may be either a batch type or a continuous type, but from the viewpoint of easily and reliably obtaining the ground granulated blast furnace slag of the present invention, the batch type is preferred. A grinding aid may be mixed during grinding. In this step, after or during the pulverization, the pulverized product obtained by pulverizing the blast furnace slag may be classified using a classification means to obtain ground granulated blast furnace slag. In addition, the coarse particles classified by the classification means (those not included in the ground granulated blast furnace slag) may be returned to the pulverizing means and pulverized again. From the viewpoint of easily and reliably obtaining the ground granulated blast furnace slag of the present invention, it is preferable to pulverize without using any classification means.

[0025] Hereinafter, an example of a method for pulverizing blast furnace slag using the above-mentioned pulverizing means to obtain ground granulated blast furnace slag will be specifically described. [Crushing method using a ball mill] When a ball mill is used as the grinding means, the proportion of fine powder in the obtained ground granulated blast furnace slag can be increased by at least one of using smaller diameter balls and extending the grinding time, thereby obtaining the ground granulated blast furnace slag of the present invention. The diameter of the balls varies depending on the shape of the ball mill and the amount of blast furnace slag to be added, but is preferably 10 to 40 mm, more preferably 15 to 25 mm. If the diameter is 10 mm or more, the time required for pulverization can be shortened. If the diameter is 40 mm or less, the 5% volume cumulative particle size and 10% volume cumulative particle size of the ground granulated blast furnace slag can be made smaller. The grinding time varies depending on the shape of the ball mill and the amount of blast furnace slag to be added, but is preferably 75 minutes or more, more preferably 90 minutes or more, and particularly preferably 120 minutes or more. If the time is 75 minutes or more, the 5% volume cumulative particle size and the 10% volume cumulative particle size of the ground granulated blast furnace slag can be made smaller. The upper limit of the time is not particularly limited, but from the viewpoint of preventing the time required for grinding from becoming excessive, it is preferably 360 minutes, more preferably 300 minutes, and particularly preferably 260 minutes.

[0026] The rotation speed of the ball mill during pulverization varies depending on the ball diameter, the amount of blast furnace slag added, and the like, but is preferably 10 to 100 rpm, more preferably 15 to 80 rpm, and particularly preferably 20 to 50 rpm. The mass ratio of the balls (total amount of balls) to the blast furnace slag (balls / blast furnace slag) varies depending on the ball diameter and the rotation speed of the ball mill, but is preferably 5 to 20, more preferably 8 to 15, and particularly preferably 9 to 12.

[0027] [Crushing method using a vertical roller mill] A classifier is usually provided at the top of the vertical roller mill. The ground material ground in the grinding section of the vertical roller mill is blown up by an air current and sent to the classifier together with the air. The ground material is then classified in the classifier and separated into fine particles and coarse particles. The coarse particles may be fed back to the grinding section of the vertical roller mill and ground. Here, the classifier is classified into a "fixed type" that does not have a rotor and a "rotary type" that has a rotor. When a vertical roller mill equipped with a fixed classifier is used as the pulverizing means, the angle of the fixed blades (fixed vanes) arranged at the inlet of the classifier for air (including the pulverized material blown up) can be adjusted to reduce the cross-sectional area of ​​the area at the inlet where the air flows into the classifier (the area through which the air can pass), thereby increasing the inflow velocity of the air and making the particle size of the fine particles to be classified smaller. By adjusting the fixed blades in this way, the fine particles of the blast furnace slag of the present invention can be obtained as the fine particles.

[0028] Furthermore, when a vertical roller mill equipped with a rotary classifier is used as the pulverizing means, the particle size of the pulverized material can be adjusted by adjusting at least one of the rotation speed of the rotor and the air volume. For example, the particle size of the fine particles to be classified can be made smaller by increasing the rotation speed of the rotor and the air volume. By adjusting the rotation speed of the rotor and the like in this way, the ground granulated blast furnace slag of the present invention can be obtained.

[0029] The ground granulated blast furnace slag of the present invention may be obtained by mixing two or more kinds of ground blast furnace slag having different particle size distributions. For example, the ground blast furnace slag may be separately ground using a plurality of grinding means, and then the resulting ground products may be mixed to obtain a mixture having a 5% cumulative particle size of 1.60 μm or less, a 10% cumulative particle size of 2.20 μm or less, and a Blaine specific surface area of ​​3,000 to 5,500 cm. 2 The ground granulated blast furnace slag of the present invention can be obtained by appropriately mixing the ingredients in a blending ratio of 0.1 to 0.1 g. EXAMPLES

[0030] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Blast furnace slag A to D: The chemical composition of each blast furnace slag and the basicity calculated using the chemical composition as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" are shown in Table 1. Granulated blast furnace slag was used as the blast furnace slag.

[0031] [Table 1]

[0032] [Example 1] The types of blast furnace slag shown in Table 2 were placed in a container with an inner diameter of 600 mm, length of 450 mm, and volume of 0.13 m 3Using a batch ball mill, the blast furnace slag fine powder with a Blaine specific surface area shown in Table 2 was obtained. The pulverization was carried out for 90 minutes under the condition that 220 kg of balls with a ball diameter of 20 mm were used for 20 kg of blast furnace slag and the rotation speed of the ball mill was 30 rpm. The 5% volume cumulative particle size (shown as "D5" in Table 2), 10% volume cumulative particle size (shown as "D10" in Table 2), 50% volume cumulative particle size (shown as "D50" in Table 2), and 90% volume cumulative particle size (shown as "D90" in Table 2) of the obtained blast furnace slag fine powder were measured using a laser diffraction particle size distribution measuring device (manufactured by Microtrac Bell Co., Ltd., product name "MT3300EX II"). Ethanol was used as the solvent used in the measurement. In addition, the 28-day activity index, 91-day activity index, and flow value ratio of the obtained blast furnace slag fine powder were measured in accordance with "JIS A 6206:2013 (Ground granulated blast-furnace slag for concrete)". As the cement, a mixture of three types of commercially available ordinary Portland cements from different manufacturing companies was used.

[0033] [Example 2] Except that the pulverization time was changed to 210 minutes, blast furnace slag fine powder was obtained in the same manner as in Example 1. Then, the 5% volume cumulative particle size, etc. of the obtained blast furnace slag fine powder were measured in the same manner as in Example 1. [Comparative Example 1] Except that the pulverization time was changed to 50 minutes, blast furnace slag fine powder was obtained in the same manner as in Example 1. Then, the 5% volume cumulative particle size, etc. of the obtained blast furnace slag fine powder were measured in the same manner as in Example 1.

[0034] [Comparative Examples 2 to 3] The blast furnace slag of the type shown in Table 2 was pulverized using a continuous vertical roller mill to obtain blast furnace slag fine powder with a Blaine specific surface area shown in Table 2. The 5% volume cumulative particle size, etc. of the obtained blast furnace slag fine powder were measured in the same manner as in Example 1. [Comparative Example 4] The types of blast furnace slag shown in Table 2 were pulverized for 60 minutes using a disk mill to obtain ground granulated blast furnace slag having the Blaine specific surface area shown in Table 2. The 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1. [Comparative Example 5] The types of blast furnace slag shown in Table 2 were pulverized for 40 minutes using a jet mill to obtain ground granulated blast furnace slag having the Blaine specific surface area shown in Table 2. The 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1.

[0035] [Example 3] The ground granulated blast furnace slag obtained in Comparative Example 3 and the ground granulated blast furnace slag obtained in Comparative Example 4 were mixed in a mass ratio of 8:2 to obtain ground granulated blast furnace slag having a Blaine specific surface area shown in Table 2. The 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1. [Example 4] The ground granulated blast furnace slag obtained in Comparative Example 3 and the ground granulated blast furnace slag obtained in Comparative Example 4 were mixed in a mass ratio of 6:4 to obtain ground granulated blast furnace slag having a Blaine specific surface area shown in Table 2. The 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1. [Example 5] The ground granulated blast furnace slag obtained in Comparative Example 3 and the ground granulated blast furnace slag obtained in Comparative Example 4 were mixed in a mass ratio of 4:6 to obtain ground granulated blast furnace slag having a Blaine specific surface area shown in Table 2. The 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1.

[0036] [Examples 6 to 12] The types of blast furnace slag shown in Table 2 were pulverized using a batch-type ball mill to obtain ground blast furnace slag having the Blaine specific surface area shown in Table 2. The pulverization was carried out using 220 kg of balls with a ball diameter of 20 mm for 20 kg of blast furnace slag at a ball mill rotation speed of 30 rpm. The grinding times in Examples 6 to 12 were 120, 210, 100, 210, 230, 240, and 230 minutes, respectively. [Reference example 1] Ground granulated blast furnace slag was obtained in the same manner as in Comparative Example 2, except that the type of blast furnace slag shown in Table 2 was used, and then the 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1. [Reference example 2] Ground granulated blast furnace slag was obtained in the same manner as in Comparative Example 4, except that the type of blast furnace slag shown in Table 2 was used, and then the 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1. [Reference example 3] The ground granulated blast furnace slag obtained in Reference Example 1 and the ground granulated blast furnace slag obtained in Reference Example 2 were mixed in a mass ratio of 8:2 to obtain ground granulated blast furnace slag having a Blaine specific surface area shown in Table 2. The 5% volume cumulative particle size and other properties of the obtained ground granulated blast furnace slag were measured in the same manner as in Example 1. The results are shown in Table 2.

[0037] [Table 2]

[0038] From Examples 1 to 12 in Table 2, the Blaine specific surface area of ​​the ground granulated blast furnace slag of the present invention is 3,140 to 5,410 cm 2 / g, but it can be seen that the activity index at 28 days, activity index at 91 days, and flow value ratio, as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)", are 81 to 101%, 95 to 110%, and 95 to 103%, respectively. On the other hand, Comparative Example 1 (Blaine specific surface area is 2,010 cm 2 / g) is 80%, which is small. For the ground granulated blast furnace slag of Comparative Examples 2 to 3 and 5 (5% volume cumulative particle size of 1.69 to 1.73 μm, 10% volume cumulative particle size of 2.23 to 2.40 μm), the activity index at 28 days was 68 to 79%, and the activity index at 91 days was 83 to 91%, indicating that the ground granulated blast furnace slag has a low activity index.

Claims

1. 5% volume cumulative particle size is 1.60 μm or less, 10% volume cumulative particle size is 2.20 μm or less, and Blaine specific surface area is 3,000 to 5,500 cm ２ / g, and a basicity as defined in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" of 1.40 to 1.

70.

2. The ground granulated blast furnace slag according to claim 1, wherein the activity index and flow value ratio values ​​as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" are 75% or more at a 28-day age, 95% or more at a 91-day age, and 95% or more at a flow value ratio.

3. A cement composition comprising the ground granulated blast furnace slag according to claim 1 or 2, cement clinker powder, and gypsum powder.

4. A method for producing ground granulated blast furnace slag according to claim 1 or 2, a blast furnace slag selection step for checking whether or not a blast furnace slag to be used as a material for the ground granulated blast furnace slag satisfies the condition that the basicity is within a range of 1.40 to 1.70 as specified in "JIS A 6206:2013 (ground granulated blast furnace slag for concrete)" and, if the blast furnace slag satisfies the condition, selecting the blast furnace slag as a material for the ground granulated blast furnace slag; The blast furnace slag selected in the blast furnace slag selection step is selected from slag having a 5% volume cumulative particle size of 1.60 μm or less, a 10% volume cumulative particle size of 2.20 μm or less, and a Blaine specific surface area of ​​3,000 to 5,500 cm ２ a blast furnace slag crushing step of crushing the blast furnace slag by a crushing means so as to obtain a ground granulated blast furnace slag having a molecular weight of 1.0 to 1.0 g; A method for producing ground granulated blast furnace slag, comprising:

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