Method for manufacturing cement additives and method for manufacturing cement compositions

Abstract

To suppress the decrease in fluidity of cement compositions containing natural zeolite. [Solution] A method for producing a cement additive. The above production method includes removing fine powder components by classifying pulverized natural zeolite. The above cement additive includes at least a portion of the pulverized material after the removal of the fine powder components.

Description

[Technical Field]

[0001] The present invention relates to a method for producing cement additives and a method for producing cement compositions. [Background technology]

[0002] Patent documents 1 and 2 disclose the preparation of cement compositions and the like by mixing zeolite with cement components. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-143317 [Patent Document 2] Japanese Patent Publication No. 2020-128315 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Traditionally, fly ash has been widely used as a cement additive, such as cement mixers and concrete admixtures. However, fly ash is coal ash generated from pulverized coal combustion boilers at coal-fired power plants. In recent years, with the aim of realizing a decarbonized society, there is a desire to reduce coal-fired power generation, which emits a large amount of CO2, and it is expected that fly ash will be depleted in the future. Therefore, the inventors of this invention investigated the use of natural zeolite, a type of natural pozzolanic, as a cement additive to replace fly ash. As a result of this investigation, it became clear that cement compositions with added natural zeolite have lower fluidity compared to cement compositions containing fly ash.

[0005] Under these circumstances, one aspect of the present invention aims to suppress the decrease in fluidity of a cement composition containing natural zeolite. [Means for solving the problem]

[0006] When preparing cement compositions containing natural zeolite, pulverized natural zeolite is typically used. After extensive research, the inventors have discovered that by removing the fine particles from the pulverized natural zeolite and then mixing it with other components for the manufacture of the cement composition, the decrease in fluidity of the cement composition containing natural zeolite can be suppressed.

[0007] That is, one aspect of the present invention is as follows. [1] A method for manufacturing cement additives, By classifying the pulverized natural zeolite, fine particles are removed. Includes, The above manufacturing method, wherein the cement additive comprises at least a portion of the pulverized material after the removal of the above-mentioned fine powder components. [2] The method for producing the cement additive according to [1], further comprising fly ash and limestone powder or both of the above cement additive. The cement additive is manufactured by the method for manufacturing the cement additive described in [3] [1] or [2], and Mix the manufactured cement additive with at least crushed cement clinker. A method for producing a cement composition, including the following: [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to produce a cement composition containing natural zeolite in which a decrease in fluidity is suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] This graph shows the particle size distribution of natural zeolite pulverized material Z1. [Figure 2] Figure 1 is a graph showing the rate of change in the particle size distribution. [Figure 3] This graph shows the particle size distribution of the three classified fractions (coarse powder component Zc, medium powder component Zm, and fine powder component Zf) obtained by classifying natural zeolite pulverized material Z1.

Mode for Carrying Out the Invention

[0010] [Method for Producing Cement Additive] One aspect of the present invention relates to a method for producing a cement additive. The method for producing the cement additive includes removing fine powder components by classifying a pulverized product of natural zeolite (also simply referred to as "pulverized product"), and the cement additive at least includes at least a part of the pulverized product after removing the fine powder components. Hereinafter, the method for producing the cement additive will be described in more detail.

[0011] <Cement Additive> In the present invention and this specification, "cement additive" includes cement admixtures and concrete admixtures. When used as a cement admixture, the cement additive can be charged into, for example, a mixer for blended cement. On the other hand, when used as a concrete admixture, the cement additive can be mixed with cement to produce concrete (mortar, concrete or cement paste). Further, the cement additive may be kneaded with other materials such as cement and water, and then cured.

[0012] The cement additive can be used, for example, for the manufacture of a cement composition, as described above. Compared to using simply crushed natural zeolite as such a cement additive, using the cement additive manufactured by the above manufacturing method can suppress the decrease in fluidity of the cement composition. The fact that the fine particles in the crushed natural zeolite cause the decrease in fluidity of the cement composition is a new finding that was not previously known. Natural zeolite contains several types of minerals, and these minerals have different hardnesses. Harder minerals are difficult to pulverize by crushing, while softer minerals are easily pulverized by crushing. Therefore, the inventors believe that there are differences in mineral composition among the multiple classified fractions separated by particle size through classification. In this regard, the inventors surmise that minerals that are easily pulverized by crushing cause a decrease in the fluidity of the concrete composition. Therefore, the inventors believe that classifying the crushed natural zeolite to separate and remove the fine particles from other classified fractions contributes to suppressing the decrease in fluidity of the concrete composition. However, the above is merely a surmise and does not limit the present invention.

[0013] <Natural Zeolite> The natural zeolite used in the above-described method for producing cement additives can be any natural zeolite and is not particularly limited. The natural zeolite may contain one or more aluminosilicate minerals. The aluminosilicate minerals may be salts containing any cation, such as calcium salts. For example, the natural zeolite may contain one or both of clinoptilolite and mordenite, and may also contain one or more other silicate minerals. Examples of other silicate minerals include anorthite, cristobalite, quartz, and biotite. Furthermore, since the aluminosilicates constituting natural zeolites are natural products and their crystallinity varies, amorphous aluminosilicates, which have low crystallinity and are identified as amorphous by X-ray diffraction (XRD) analysis, may also be included. In one form, an example of a natural zeolite is one in which the content (by mass) of either clinoptilolite or mordenite is the highest among the various components identified as aluminosilicate minerals by XRD analysis. However, the above example is merely one example and does not limit the present invention. Furthermore, the zeolite purity determined by XRD analysis for natural zeolites can be, for example, 50.0% or more, 55.0% or more, or 60.0% or more, or it can be, for example, 90.0% or less, 80.0% or less, or 70.0% or less, but is not particularly limited. Note that the "%" for zeolite purity is by mass.

[0014] <Removal of fine particles from natural zeolite pulverized material> (Powdered natural zeolite) As the pulverized natural zeolite, it is possible to use natural zeolite that has been pulverized using known pulverizers such as ball mills and vertical roller mills. In order to improve the efficiency of pulverizing the natural zeolite, it is preferable to add a pulverizing aid. Examples of pulverizing aids include diethylene glycol, triethanolamine, and triisopropanolamine. The addition ratio of these pulverizing aids is preferably 0.01 to 1 part by mass per 100 parts by mass of natural zeolite. One indicator of particle size is the Blaine specific surface area. "Blaine specific surface area" is the specific surface area measured by the Blaine method, and is determined according to JIS A 6201:2015 and JIS R 5201 8.1, which is cited in JIS 8.5.2. From the perspective of improving the strength of concrete prepared by adding the above-mentioned cement additive, the Blaine specific surface area of ​​unclassified crushed natural zeolite should be 7500 cm². 2 It is preferable that it be 9000 cm² or more. 2 It is more preferable that the amount be 1 / g or more. On the other hand, from the viewpoint of improving the fluidity of concrete prepared by adding the above cement additive, the Blaine specific surface area of ​​the crushed natural zeolite before classification should be 15,000 cm². 2 It is preferable that the value be less than or equal to 13500 cm². 2 It is more preferable that the value be less than or equal to / g. Another indicator of particle size is the BET specific surface area. "BET specific surface area" refers to the value obtained by applying the BET formula to the adsorption isotherm of the object being measured using the nitrogen adsorption method. For example, the BET specific surface area of ​​pulverized natural zeolite before classification is 80,000 to 300,000 cm². 2 It can be in the range of / g, from 150,000 to 250,000 cm 2 It is preferable that the range is within / g. Another indicator of particle size is the 50% volume cumulative diameter (D50). "D50 (volume cumulative)" refers to the particle size of the 50% volume cumulative diameter in the cumulative particle size distribution of the object being measured, obtained by laser diffraction and scattering. The D50 (volume cumulative) of unclassified natural zeolite pulverized material can be in the range of, for example, 3 to 15 μm. The density of the unclassified natural zeolite pulverized material is determined according to Clause 7 of JIS R 5201, which is referenced in JIS A 6201:2015 and JIS 8.4, for example, 2.00 to 2.80 g / cm³. 3 It can be within the range of However, the above-mentioned ranges for Brain specific surface area, BET specific surface area, D50, and density are illustrative and do not limit the present invention.

[0015] (classification) Dry or wet classifiers can be used for classifying pulverized natural zeolite. For example, dry classifiers include centrifugal air classifiers and airflow classifiers. "Classification" is a process of separating powder according to particle size, and may be separated into two classification fractions with different particle sizes (coarse powder component and fine powder component), or into three classification fractions with different particle sizes (coarse powder component, medium powder component and fine powder component), or into four or more classification fractions with different particle sizes. As mentioned above, natural zeolite usually contains multiple types of minerals, and therefore the pulverizability differs depending on the hardness of each mineral. For this reason, the particle size distribution of pulverized natural zeolite usually contains multiple peaks. In classifying pulverized natural zeolite, it is preferable to set the classification point so as to separate the multiple peaks. For example, in a curve showing the rate of change in particle size distribution, the point where the rate of change is near zero can be defined as the classification point. Each component separated by classification has a sharper particle size distribution than the crushed material before classification. The n-value can be cited as an indicator of particle size distribution. The "n-value" is the Talbot curve P=(d / D) nIt is the exponent n at ×100 and is determined as the gradient of logd in the double logarithmic graph of log(P / 100) and logd. P is the cumulative passing rate, D is the maximum particle size, d is an arbitrary particle size, and n is the exponent. The larger the n value, the sharper the particle size distribution. Each component obtained by classifying the natural zeolite pulverized product has an n value larger than the n value of the natural zeolite pulverized product before classification. The n value of each component obtained by classifying the natural zeolite pulverized product can be, for example, in the range of 1.5 to 4.0, preferably 2.0 to 3.0, but is not limited to this range.

[0016] In the present invention and this specification, the "fine powder component" removed by classification means the classification fraction on the finest powder side among a plurality of classification fractions separated by classification. All of the classified product of the pulverized product from which the classification fraction on the finest powder side has been removed may be used as a component of the cement additive, or a part thereof may be used as a component of the cement additive. For example, after classifying the pulverized product into two classification fractions (coarse powder component and fine powder component) having different particle sizes, all of the coarse powder component may be used as a component of the cement additive, or a part of the coarse powder component may be used as a component of the cement additive. When the pulverized product is classified into three classification fractions (coarse powder component, medium powder component and fine powder component) having different particle sizes, a part or all of the coarse powder component may be used as a component of the cement additive, and a part or all of the medium powder component may be used as a component of the cement additive. Further, a part or all of the coarse powder component and a part or all of the medium powder component may be mixed at an arbitrary ratio and used as a component of the cement additive. The above points are the same when the pulverized product is classified into four or more classification fractions having different particle sizes. In any embodiment, the cement additive does not include the classification fraction on the finest powder side in the pulverized product. The present inventor believes that this is the reason why the decrease in the fluidity of the cement composition can be suppressed by the above cement additive. As an example, the Blaine specific surface area of the fine powder component is 15000 cm 2 / g or more or 20000 or more cm 2 / g or more, and the BET specific surface area of the fine powder component is 140000 cm2 / g or more or 160,000cm 2 It can be 1 / g or more. From the viewpoint of improving the fluidity of concrete prepared by adding the above-mentioned cement additive, the classification point when removing fine particles is preferably 2.5 μm or higher, and more preferably 5 μm or higher. On the other hand, from the viewpoint of improving the strength of concrete prepared by adding the above-mentioned cement additive, the classification point when removing fine particles is preferably 15 μm or lower, and more preferably 10 μm or lower. To increase the strength of the concrete, coarse particles may be removed by classification (for example, classification points of 15 μm and 10 μm). If the fluidity of the concrete is low, the fluidity can be improved by increasing the classification point. However, the values ​​stated herein are illustrative and do not limit the present invention.

[0017] The Blaine specific surface area of ​​the crushed natural zeolite contained in the above cement additive (i.e., a classified product of crushed natural zeolite from which at least the fine powder components have been removed, hereinafter the same) is 2000 cm², from the viewpoint of improving the strength of concrete prepared by adding the above cement additive. 2 It is preferable that the amount be 2300 cm or more, and 2300 cm 2 It is more preferable that the amount be 1 / g or more. On the other hand, from the viewpoint of improving the fluidity of concrete prepared by adding the above cement additive, the Blaine specific surface area of ​​the crushed natural zeolite contained in the above cement additive should be 9000 cm². 2 It is preferable that the value be less than or equal to 8000 cm². 2 It is more preferable that the value be less than or equal to / g. The BET specific surface area of ​​the crushed natural zeolite contained in the above cement additive is 60,000 to 150,000 cm². 2 It is preferable that the range is in the range of / g, and is between 80,000 and 120,000 cm³. 2 It is more preferable that the range is within / g. The D50 (volume accumulation) of the crushed natural zeolite contained in the above cement additive is preferably in the range of 4 to 30 μm, and more preferably in the range of 7 to 25 μm.

[0018] The above cement additive contains at least a classified natural zeolite pulverized material from which at least the fine powder components have been removed. The above cement additive may consist only of the above classified material, or it may contain one or more other components. When manufacturing a cement additive containing the above classified material and two or more other components, the above classified material and the two or more other components can be mixed simultaneously or in any order. The above cement additive preferably contains 50 parts by mass or more of the above classified material, and may also contain 100 parts by mass, based on 100 parts by mass of the total cement additive. The content of other components (the total content of two or more other components if included) is preferably 50 parts by mass or less, and more preferably in the range of 25 to 40 parts by mass, based on 100 parts by mass of the total cement additive. Other components include pozzolanic powders such as volcanic ash, fly ash, and calcined clay; mineral powders such as limestone, silica, and steelmaking slag; and powders of potential hydraulic materials such as blast furnace slag. For example, the specific surface area of ​​fly ash is 3,000 to 10,000 cm². 2 It is preferable that the range is in the range of / g, and 4000 to 8000 cm 2 It is more preferable that the range is within / g. For limestone powder, 3000~10000cm³ 2 It is preferable that the range is within / g, and is between 4500 and 8000 cm. 2 It is even more preferable that the range is in the g / g range. For blast furnace slag powder, 3000 to 10000 cm³. 2 It is preferable that the range is in the range of / g, and 4000 to 8000 cm 2 It is more preferable that the range is within / g.

[0019] Furthermore, the above-mentioned cement additive may also contain, as other components, one or more selected from the group consisting of gypsum powder, such as dihydrate gypsum, flue gas desulfurization gypsum, phosphate gypsum, titanium gypsum, hydrofluoric acid gypsum, refined gypsum, hemihydrate gypsum, and anhydrous gypsum. The amount added (or the total content if multiple types are included) is preferably 5 parts by mass or less, and more preferably in the range of 1 to 3 parts by mass, based on SO3 equivalent, with the total amount of cement additive being 100 parts by mass.

[0020] In one embodiment, the cement additive may include either or both fly ash and limestone powder.

[0021] The other components mentioned above can, in one form, be included as components of the cement additive, and in another form, be used by mixing them with the cement additive during the manufacture of the cement composition. For the amount of the other components to be mixed in the latter form, refer to the previous description regarding their content in the cement additive.

[0022] The cement additive obtained by the manufacturing method described above can be used for the manufacture of cement compositions.

[0023] [Method for manufacturing cement composition] One aspect of the present invention relates to a method for producing a cement composition. The method for producing the cement composition includes producing a cement additive by the method for producing the cement additive described above, and mixing the produced cement additive with at least crushed cement clinker. By producing a cement composition by such a method, it is possible to provide a cement composition that contains natural zeolite in which a decrease in fluidity is suppressed. The method for producing the above cement composition will be described in more detail below.

[0024] In the present invention and this specification, "cement composition" includes cement and concrete. "Concrete" includes mortar, concrete, and cement paste.

[0025] The above-mentioned cement additive may be, for example, a component that replaces some or all of the cement additives conventionally used in cement compositions. Fly ash is an example of a conventionally used cement additive.

[0026] When manufacturing cement as a cement composition, the above-mentioned cement additive can be used as a cement mixer. The essential component to be mixed with the cement mixer is crushed cement clinker, and other optional components include, for example, gypsum powder and limestone powder. The type of cement clinker is not particularly limited, and examples include ordinary Portland cement clinker, rapid-hardening Portland cement clinker, moderate-heat Portland cement clinker, low-heat Portland cement clinker, and eco-cement clinker. Among these, ordinary Portland cement clinker is preferred due to its high versatility. The type of gypsum is also not particularly limited, and examples include dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum. As gypsum powder, crushed gypsum can be used. For example, the above-mentioned cement additive can be added to Portland cement such as ordinary Portland cement, rapid-strength Portland cement, moderate-heat Portland cement, and low-heat Portland cement, or to eco-cement, which are mixed with crushed cement clinker and gypsum powder. Furthermore, limestone powder can be added simultaneously with or separately from the addition of the above-mentioned cement additive.

[0027] In one embodiment, when producing concrete as a cement composition, cement containing the above-mentioned cement additive can be used for the production of concrete. More specifically, concrete can be produced by mixing cement containing the above-mentioned cement additive with components for concrete production such as aggregate, water, water-reducing agent, gypsum powder, limestone powder, or by further mixing it with cement that does not contain the above-mentioned cement additive. Furthermore, when manufacturing concrete as a cement composition, in one embodiment, the above-mentioned cement additive can be used as a concrete admixture. Other components to be mixed with the concrete admixture include aggregate, cement (including at least crushed cement clinker), water, water-reducing agent, gypsum powder, limestone powder, etc. That is, in one embodiment, the above-mentioned cement additive is mixed with crushed cement clinker in the form contained in the cement during cement manufacturing.

[0028] In cement, the water content is preferably in the range of 30 to 70 parts by mass, based on 100 parts by mass of the total cement amount excluding aggregate and water. As water-reducing agents, lignin-based, naphthalene sulfonic acid-based, melamine-based, or polycarboxylic acid-based water-reducing agents, AE water-reducing agents, high-performance water-reducing agents, or high-performance AE water-reducing agents can be used. In cement, the water-reducing agent content is preferably 4 parts by mass or less, more preferably in the range of 0.5 to 3.5 parts by mass, and even more preferably in the range of 1 to 3 parts by mass, based on 100 parts by mass of the total amount of cement excluding aggregate and water. As aggregates, fine aggregates (e.g., river sand, land sand, crushed sand, etc.) and / or coarse aggregates (e.g., river gravel, mountain gravel, crushed stone, etc.) commonly used in the manufacture of mortar and concrete can be used. In addition, waste materials such as molten slag (e.g., produced by melting one or more selected from municipal solid waste, municipal solid waste incineration ash, and sewage sludge incineration ash), blast furnace slag, steelmaking slag, copper slag, insulator scraps, glass cullet, ceramic waste, clinker ash, waste bricks, and concrete waste can be used as part or all of the aggregate. Furthermore, admixtures such as air-entraining agents and defoaming agents may be used as needed.

[0029] In the cement composition produced by the above manufacturing method, the content of the cement additive can be, with the total mass of the cement composition (excluding aggregate, cement clinker pulverized material, and gypsum powder if present) as 100% by mass, for example, 5% or more by mass or 10% or more by mass from the viewpoint of initial strength and CO2 reduction of the cement composition, and for example, 50% or less by mass, 40% or less by mass, 30% or less by mass, or 20% or less by mass from the viewpoint of long-term strength. [Examples]

[0030] The present invention will be further described below based on examples. However, the present invention is not limited to the embodiments shown in the examples.

[0031] [Natural Zeolite Powder Z1] Natural zeolite (zeolite rock) was crushed using a ball mill to obtain natural zeolite pulverized material Z1.

[0032] [Coarse powder component Zc, medium powder component Zm, fine powder component Zf] A portion of the natural zeolite pulverized material Z1 was collected, and its particle size distribution was measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac-Bell MT3300 EX II). The measurement results are shown in Figure 1. From Figure 1, it can be confirmed that the particle size distribution of the natural zeolite pulverized material Z1 has multiple peaks. Figure 2 is a graph showing the rate of change in the particle size distribution shown in Figure 1. To separate the multiple peaks in the particle size distribution of the natural zeolite pulverized material Z1, the points where the rate of change in the particle size distribution shown in Figure 2 is near zero (particle size 5 μm, 10 μm) were defined as classification points, and the natural zeolite pulverized material Z1 was classified using a centrifugal air classifier (O-SEPA, manufactured by Taiheiyo Engineering Co., Ltd.) to separate it into three classification fractions (coarse powder component Zc (classification point: 10 μm~), medium powder component Zm (classification point: 5~10 μm), and fine powder component Zf (classification point: ~5 μm)). A portion of the above three classification fractions obtained by classifying the natural zeolite pulverized material Z1 was taken, and the particle size distribution was measured using a laser diffraction / scattering particle size distribution analyzer (MT3300 EX II, manufactured by Microtrac-Bell). The measurement results are shown in Figure 3. The results shown in Figure 3 confirm that the above classification method allowed for the separation of multiple peaks in the particle size distribution of the natural zeolite pulverized material Z1.

[0033] For each of the natural zeolite pulverized material Z1, coarse powder component Zc, medium powder component Zm, and fine powder component Zf, the n-value was determined from the particle size distribution measurement results described above using the method previously stated. The results are shown in Table 1. As shown in Table 1, the n-values ​​of the coarse powder component Zc, medium powder component Zm, and fine powder component Zf are greater than the n-value of the natural zeolite pulverized material Z1 before classification. From these results, it can be confirmed that the particle size distribution of the coarse powder component Zc, medium powder component Zm, and fine powder component Zf is sharper than that of the natural zeolite pulverized material Z1 before classification.

[0034] [Physical property measurement] For each of the components shown in Table 1, the density, Blaine specific surface area, and BET specific surface area were measured using the method described above. In Table 1, "ordinary Portland cement" refers more specifically to crushed ordinary Portland cement clinker. A fluidized specific surface area automatic measuring device (Shimadzu FlowSorb 2305) was used to measure the BET specific surface area. The measurement results are shown in Table 1.

[0035] [Table 1]

[0036] [Composition analysis] The mineral composition and zeolite purity of each of the natural zeolite pulverized material Z1, coarse powder component Zc, medium powder component Zm, and fine powder component Zf were determined by X-ray diffraction analysis. X-ray diffraction analysis was performed using a Bruker D8 ADVANCE X-ray diffractometer, and the content of each mineral phase was determined by fitting the theoretical profile of each mineral shown in Table 2 to the measured profile using the Rietveld method. The results are shown in Table 2. In Table 2, "-Ca" in "clinoptilolite-Ca" indicates that it is a calcium salt. Note that "%" for mineral composition is based on mass.

[0037] [Table 2]

[0038] [Examples 1-11, Comparative Examples 1-3, Reference Examples 1-4] (1) Preparation of mortar Using the cement compositions shown in Table 3, mortar mixing and preparation were carried out in accordance with the description of JIS R5201:2015 regarding mortar for strength testing. The mixing ratios shown in Table 3 are the mass ratios of powders excluding aggregates. Gypsum powder is included only in the OPC at 2% by mass in terms of SO3. However, an air content adjuster was added at 0.04% by mass per 100% by mass of the total powder amount (B in Table 3), and a polycarboxylic acid-based high-performance water-reducing agent (SP agent: Super Plasticizer) was added so that the 15-strand flow in the flow test conducted in accordance with JIS R5201:2015 was 230 mm ± 20 mm. The amount of SP agent added in this case was the value shown in Table 3 per 100% by mass of the total powder amount. The 0-strand flow of the mortar thus prepared in the flow test conducted in accordance with JIS R5201:2015 was the value shown in Table 3. Regarding the amount of SP agent added, the standard addition amount recommended by the manufacturer of the SP agent used is 3.0% by mass or less. Therefore, if the amount of SP agent added as listed in Table 3 is 3.0% by mass or less, it can be said that the fluidity can be controlled within the range of typical additive amounts.

[0039] (2) Measurement of air volume Using the mortar to which the fluidity was adjusted by adding the SP agent as described in (1) above, the air content was measured using a mortar air meter in accordance with JIS A1171:2016. The air content is preferably 2.0% or less.

[0040] (3) Measurement of compressive strength Using the mortar to which the fluidity was adjusted by adding the SP agent as described in (1) above, cylindrical specimens with a diameter of 5 cm and a length of 10 cm were molded in accordance with JSCE-G 505-2010, and the compressive strength was measured at 3 days, 7 days, 28 days, and 91 days of age.

[0041] The results are shown in Table 3.

[0042] [Table 3]

[0043] The results shown in Table 3 confirm the following points. (1) Examples 1 to 11 are examples in which the medium powder component Zm or the coarse powder component Zc of natural zeolite pulverized material Z1 was used as a cement additive. In Comparative Examples 1 and 2, which used natural zeolite Z1 as a cement additive, and Comparative Example 3, which used the fine powder component Zf of natural zeolite pulverized material Z1, the amount of SP agent added was more than 3.0% by mass, whereas in Examples 1 to 11, the amount of SP agent added was 3.0% by mass or less. This result indicates that the reduction in fluidity of the cement composition containing natural zeolite was suppressed by removing the fine powder component Zf of natural zeolite pulverized material Z1. (2) The various performance characteristics of Examples 1 to 11 were comparable to those of Reference Examples 1 to 5, which included fly ash. This result indicates that cement additives prepared by removing fine powder components through classification of natural zeolite pulverized material can be used as a substitute for fly ash. [Industrial applicability]

[0044] One aspect of the present invention is useful in the field of manufacturing cement, concrete, and the like.

Claims

1. A method for manufacturing cement additives, By classifying the pulverized natural zeolite, fine particles are removed. Includes, The manufacturing method wherein the cement additive comprises at least a portion of the pulverized material after the removal of the fine powder components.

2. The method for producing a cement additive according to claim 1, wherein the cement additive further comprises one or both of fly ash and limestone powder.

3. A cement additive is manufactured by the method for manufacturing a cement additive described in claim 1 or 2, and Mix the manufactured cement additive with at least crushed cement clinker. A method for producing a cement composition, including the following:

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