JP6874883B1 - Cement clinker and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement clinker and a cement composition in which an increase in b value is suppressed without reducing the amount of waste and by-products used.
SOLUTION: A _{cement clinker containing Al 2} O ₃ , Fe ₂ O ₃ , MgO, MnO and ZnO and satisfying the formula (1).
W _Al2O3 x 0.2273 + W _Fe2O3 x (-0.9262) + W _MgO x (-0.4991) + W _MnO x (-1.6387) + W _ZnO x (-5.0678) <-2.4500
... Equation (1)
[Selection diagram] None

Description

The present invention relates to cement clinker and cement compositions, especially ordinary Portland cement.

The color tone of the cement composition affects the color tone of the mortar and concrete products using it, and the larger the b value of the Lab color space of the cement composition, the larger the b value of the mortar and concrete products using it. It is yellowish.
Conventionally, the b value is greatly affected by the contents of _{Al 2} O ₃ , Fe ₂ O ₃ and Mg O, which are the main components of the cement clinker that is the basis of the cement composition, and is _{also a trace component, Na 2} O. , TiO ₂ , MnO ₂ and Cr ₂ O ₃ were also known to be affected (Non-Patent Document 1).

On the other hand, in recent years, the cement industry has accepted various wastes and by-products containing a large amount of _{Al 2} O _{3 such as construction-generated soil as a raw material for cement clinker, so that the content of Al 2} O _{3 in} cement clinker has increased. Tend to do.

"C & C Encyclopedia-Basic Explanation of Cement and Concrete Chemistry", published by Cement Association, July 1996, P.M. 15-16

As in Non-Patent Document 1, there is a concern that the b value in the Lab color space of the cement composition _{increases as the content of Al 2} O _{3 in the cement clinker increases.} Therefore, when the amount of waste and by-products used as raw materials for cement clinker is increased, the b value of the cement composition tends to increase. Therefore, it is required to suppress an increase in the b value of the cement composition without reducing the amount of waste and by-products used.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cement clinker and a cement composition in which an increase in b value is suppressed without reducing the amount of waste and by-products used.

In cement clinker production and cement production, the b value in the Lab color space and the physical characteristics of cement _{are affected not only by the main components such as Al 2} O ₃ , but also by various trace components and production conditions.
Non-Patent Document 1 reports on the effects of _{Al 2} O ₃ , Fe ₂ O ₃ , MgO, Na ₂ O, TiO ₂ , MnO ₂ and Cr ₂ O _{3 on the b value.} It was difficult to suppress the increase in the b value without reducing the amount of waste and by-products used as the cement raw material only by adjusting the amount.

式中、Ｗ_{Ａｌ２Ｏ３}はセメントクリンカ全量に対するＡｌ_２Ｏ_３の含有量（質量％）を表し、Ｗ_{Ｆｅ２Ｏ３}はセメントクリンカ全量に対するＦｅ_２Ｏ_３の含有量（質量％）を表し、Ｗ_ＭｇＯはセメントクリンカ全量に対するＭｇＯの含有量（質量％）を表し、Ｗ_ＭｎＯはセメントクリンカ全量に対するＭｎＯの含有量（質量％）を表し、Ｗ_ＺｎＯはセメントクリンカ全量に対するＺｎＯの含有量（質量％）を表す。
［２］ ボーグ式で算出された３ＣａＯ・ＳｉＯ_２の割合が５０．０質量％以上、７５．０質量％以下であり、
ボーグ式で算出された２ＣａＯ・ＳｉＯ_２の割合が５．０質量％以上、２５．０質量％以下であり、
ボーグ式で算出された３ＣａＯ・Ａｌ_２Ｏ_３及び４ＣａＯ・Ａｌ_２Ｏ_３・Ｆｅ_２Ｏ_３の合計の割合が１５．０質量％以上、２２．０質量％以下である［１］に記載のセメントクリンカ。
［３］ 前記３ＣａＯ・ＳｉＯ_２におけるＡｌ_２Ｏ_３の含有量（Ａｌ_２Ｏ_３＿Ｃ_３Ｓ）が１．０００質量％以上である請求項１に記載のセメントクリンカ。
［４］ 請求項１又は２に記載のセメントクリンカと、石膏とを含むセメント組成物。 Therefore, the present inventors have made considering the components of the cement composition in detail, the content of _Al 2 _{O 3} to cement clinker total amount _(W Al2 O3), the content of _{Fe 2 O 3 (W Fe2O3)} , _{As a result of examining the content of MgO} (W MgO), the content of _MnO (W MnO) and the content of _ZnO (W ZnO) in detail, by examining the content of each compound with respect to the total amount of cement clinker, waste It was also found that a cement composition in which an increase in the b value was suppressed could be obtained without reducing the amount of by-products used.
That is, the present invention provides the following [1] to [4].
[1] Containing Al ₂ O ₃ , Fe ₂ O ₃ , MgO, MnO and ZnO.
A cement clinker that satisfies the following formula (1).

_{Wherein, W Al2 O3} represents the content of _Al 2 _{O 3} to cement clinker total amount _{(mass%), W Fe2O3} represents the content of _Fe 2 _{O 3} to cement clinker total amount _{(mass%), W MgO} cement clinker The content of MgO (% by mass) with _{respect to the total amount, W MnO} represents the content of MnO (% by mass) with _{respect to the total amount of cement clinker, and W ZnO} represents the content (% by mass) of ZnO with respect to the total amount of cement clinker.
_{[2] The ratio of 3CaO · SiO 2} calculated by the Borg equation is 50.0% by mass or more and 75.0% by mass or less.
_{The ratio of 2CaO · SiO 2} calculated by the Borg formula is 5.0% by mass or more and 25.0% by mass or less.
_{The total ratio of 3CaO / Al 2} O ₃ and 4 CaO / Al ₂ O ₃ / Fe ₂ O ₃ calculated by the Borg equation is 15.0% by mass or more and 22.0% by mass or less [1]. Cement clinker.
[3] the cement clinker according to claim 1 the content of _Al 2 _{O 3} in _{3CaO · SiO 2 (Al 2 O} 3 _C 3 S) is 1.000 mass% or more.
[4] A cement composition containing the cement clinker according to claim 1 or 2 and gypsum.

According to the present invention, it is possible to obtain a cement clinker and a cement composition by suppressing an increase in the b value of the Lab color space without reducing the amount of waste and by-products used.

Hereinafter, the cement clinker and the cement composition of the present invention will be described in detail.

[Cement clinker]
The cement clinker of the present invention is preferably commonly used for Portland cement.

The cement clinker of the present invention is a main component constituting the cement composition, and is limestone (CaO component), clay (Al ₂ O ₃ component, SiO ₂ component), silica stone (SiO ₂ component) and iron oxide raw material (Fe). ₂ O ₃ component) and the like are mixed and fired to produce. The cement clinker of the present invention contains industrial waste such as coal ash, construction soil, steelmaking slag, blast furnace slag, converter slag, by-product gypsum, municipal waste incineration ash, and by-products generated in the production process as raw materials. Is also good.
The contents of SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ and CaO are measured in accordance with JIS R 5204: 2019 “X-ray fluorescence analysis method for cement”.

<Main ingredients>
_{The content of SiO 2} of the cement clinker of the present invention is preferably 15.00% by mass or more, more preferably 17.00% by mass or more, and further preferably 18.00% by mass or more. It is preferably 30.00% by mass or less, more preferably 25.00% by mass or less, and further preferably 23.000% by mass or less.

_{Al 2} O ₃ content of the cement clinker of the present invention (W _{Al 2O 3} % by mass)
It is preferably 2.00% by mass or more, more preferably 4.00% by mass or more, further preferably 4.50% by mass or more, and preferably 10.00% by mass or less. It is more preferably 8.00% by mass or less, and further preferably 7.00% by mass or less.

Preferably the content of _Fe 2 _{O 3} in the cement clinker of the present invention _{(W Fe2 O3} wt%) is 1.00 mass% or more, more preferably at least 1.50 wt%, 2.00 wt% It is more preferably 10.00% by mass or less, more preferably 7.00% by mass or less, and further preferably 5.00% by mass or less.

The CaO content of the cement clinker of the present invention is preferably 50.00% by mass or more, more preferably 55.00% by mass or more, further preferably 60.00% by mass or more, 80. It is preferably 0.00% by mass or less, more preferably 75.00% by mass or less, and further preferably 70.00% by mass or less.

<trace components>
The cement clinker of the present invention contains MgO, MnO and ZnO as trace components. The MgO and MnO contents are measured in accordance with JIS R 5204: 2019 "Fluorescent X-ray Analysis Method for Cement". The ZnO content is measured in accordance with JCAS I-53: 2018 “Method for quantifying trace components in cement”.
MgO is introduced into cement clinker, for example, by using slag containing a large amount of MgO as a raw material for cement clinker.
MnO is introduced into cement clinker by using, for example, blast furnace slag and converter slag as raw materials for cement clinker.
ZnO is introduced into cement clinker, for example, by using municipal waste incineration ash as a raw material for cement clinker.

_{The MgO content (W MgO} mass%) of the cement cleaner of the present invention is preferably 0.05% by mass or more, more preferably 0.2% by mass or more, and more preferably 0.5% by mass or more. It is more preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and further preferably 2.5% by mass or less.

_{The MnO content (W MnO} mass%) of the cement clinker of the present invention is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and 0.03% by mass or more. It is more preferably 0.80% by mass or less, more preferably 0.50% by mass or less, and further preferably 0.30% by mass or less.

_{The ZnO content (W ZnO} mass%) of the cement clinker of the present invention is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and 1.50% by mass or less. It is preferable, it is more preferably 1.00% by mass or less, and further preferably 0.90% by mass or less.

<Equation (1)>
The cement clinker of the present invention contains at least Al ₂ O ₃ , Fe ₂ O ₃ , MgO, MnO and ZnO, and satisfies the relationship of the formula (1).

When the amount of industrial waste or the like as a raw material for cement clinker is increased (W _Al2O3 becomes large), the b value in the Lab color space also becomes large, and the cement composition becomes yellowish. Therefore, the b value of the cement composition can be maintained by adjusting _{W Fe2O3} , W _MgO , W _MnO and W _ZnO so as to satisfy the formula (1). Patent Document 1 discloses that the b value is _{affected by Al 2} O ₃ , Fe ₂ O ₃ , MgO, Na ₂ O, TiO ₂ , MnO ₂ and Cr ₂ O ₃ , but in the present invention, Al is affected. _{By optimizing the relationship between the contents of 2} O ₃ , Fe ₂ O ₃ , MgO, MnO and ZnO, it is possible to more effectively suppress the increase in the b value of the cement composition.
Further, W _Al2O3 , W Fe2O3, W _MgO , W _MnO and W _{ZnO can be appropriately adjusted depending on} the raw materials used and their combinations.

The left side of the formula (1) is less than −2.5400, but from the viewpoint of suppressing the increase in the b value, it is more preferably -2.6000 or less, further preferably -2.7000 or less. It is even more preferable that it is -2.88 or less.
The lower limit of the left side of the formula (1) is not particularly limited, but is more preferably -3,8000 or more from the viewpoint of obtaining a practical compressive strength when procuring raw materials or using mortar, and -3. It is more preferably .6000 or more, and even more preferably −3.55000 or more.

<Cement clinker composition>
Cement clinker of the present invention, 3CaO · _SiO 2 _{(abbreviation: C 3 S), 2CaO ·} SiO 2 ( _{abbreviation: C 2 S), 3CaO ·} Al 2 O 3 ( _{abbreviation: C} 3 A), and 4CaO · Al ₂ Includes O ₃ and FeO ₃ (abbreviation: C ₄ AF). Cement clinker is _{composed of the main minerals of alite (C 3} S) and belite (C ₂ S) and the aluminate phase (C ₃ A) and ferrite phase (C ₄ AF) existing between the crystals of the main minerals. It is composed of interstitial phases and the like.

The ratios of C ₃ S, C ₂ S, C ₃ A and C _{4 AF in cement clinker are CaO, SiO 2} , Al ₂ O in cement clinker measured by JIS R 5204: 2019 “X-ray fluorescence analysis method of cement”. _From the ratio of 3 and Fe ₂ O ₃ , it can be obtained by a calculation formula called the Borg formula in the field of cement chemistry (for example, "Cement Science" edited by Masaki Daimon, Uchida Otsuruho (1989), p.11. reference).

<Percentage of _{3CaO · SiO 2 (C 3 S} )>
_{The ratio of 3CaO · SiO 2} calculated by the Borg formula in the cement clinker of the present invention is preferably 50.0% by mass or more because the strength of concrete or mortar produced by using the cement clinker can be set to a practical level. It is more preferably 52.0% by mass or more, further preferably 54.0% by mass or more, and 75.0% by mass or less because the heat of hydration of the cement composition can be suppressed. It is more preferably 70.0% by mass or less, further preferably 65.0% by mass or less.

<Ratio of 2CaO · SiO ₂ (C ₂ S)>
Proportion of 2CaO · SiO ₂ calculated by the Borg type in the cement clinker of the present invention, the higher the proportion of 3CaO · _{SiO 2,} 5.0 mass since it is suppressed that the heat of hydration of the cement composition is too high % Or more, more preferably 10.0% by mass or more, further preferably 15.0% by mass or more, and the short-term strength of concrete or mortar produced by cement clinker is above the practical level. Therefore, it is preferably 25.0% by mass or less, and more preferably 24.0% by mass or less.

<Total proportion of _{3CaO · Al 2 O 3 (C} 3 A) and _{4CaO · Al 2 O 3 · FeO} 3 (C 4 AF)>
_{The total ratio of 3CaO · Al 2} O ₃ and 4 CaO · Al ₂ O ₃ · FeO ₃ calculated by the Borg formula in the cement clinker of the present invention is a liquid when the amount of the liquid phase generated during firing of the cement clinker is small. The solid-liquid phase reaction due to phase intervention may not proceed rapidly, the firing of the cement clinker may be insufficient, and dust is scattered during the cement clinker, blocking the radiant heat from the burner, so that the cement Since firing of clinker may not be carried out efficiently, it is preferably 15.0% by mass or more, more preferably 16.0% by mass or more, and further preferably 17.0% by mass or more. Since the short-term strength of concrete or mortar produced by cement clinker can be set to a practical level or higher, it is preferably 22.0% by mass or less, and more preferably 21.0% by mass or less.

<Proportion of _{3CaO · Al 2 O 3 (C} 3 A)>
_{The ratio of 3CaO · Al 2} O ₃ calculated by the Borg formula in the cement clinker of the present invention suppresses the decrease in viscosity of the liquid phase generated during the firing of the cement clinker, and appropriately advances the granulation of the cement clinker. It is preferable that it is 3.0% by mass or more because it is possible to suppress the layer pressure in the clinker cooler from becoming constant due to the reduction in the particle size of the cement clinker and to reduce the heat of hydration. It is more preferably 0.0% by mass or more, further preferably 7.0% by mass or more, and 15.0% by mass or less because the layer pressure in the clinker cooler becomes constant and the cement clinker can be rapidly cooled. Is preferable, and it is more preferably 12.0% by mass or less.

<Proportion of _{4CaO · Al 2 O 3 · FeO} 3 (C 4 AF)>
Proportion of _{4CaO · Al 2 O 3 · FeO} 3 calculated by the Borg type in the cement clinker of the present invention, it is possible to suppress the heat of hydration of the cement composition, is preferably 5.0 mass% or more , 7.0% by mass or more, more preferably 8.5% by mass or more, and 13.0% by mass because the short-term strength of concrete or mortar produced by cement clinker can be set to a practical level or more. % Or less, more preferably 11.0% by mass or less.

<Al ₂ O ₃ _C ₃ S>
The content of _Al 2 _{O 3} contained in 3CaO · SiO ₂ in the cement clinker of the present invention _{(Al 2 O 3 _C 3 S} ) is determined by EPMA measurement described later.
Since the strength of concrete or mortar produced by using a cement cleaner can be set to a practical level, it is preferably 1.000% by mass or more, but when higher strength is required, it is 1.100% by mass or more. More preferably, it is more preferably 1.200% by mass or more, further preferably 1.205% by mass or more, and the upper limit is not particularly limited, but the heat of hydration of the cement composition is suppressed. It is more preferably 1.800% by mass or less, more preferably 1.600% by mass or less, and further preferably 1.500% by mass or less.

[Manufacturing method of cement clinker]
The cement clinker of the present invention can be produced, for example, as follows.
As the cement clinker raw material, those containing at least Mg, Mn and Zn in addition to Ca, Si, Al and Fe are used. As long as it contains the above elements, it can be used in any form such as elemental substances, oxides, and carbon oxides, and mixtures thereof can be used. For example, natural raw materials include limestone, clay, silica stone, and iron oxide raw materials, and examples of industrial raw materials include waste raw materials containing the above elements, blast furnace slag, and fly ash. Regarding the mixing ratio of the clinker raw material, it is preferable to mix the raw material so as to have a component composition corresponding to the target Borg formula value and satisfy the above formula (1).

Then, the cement clinker raw material mixed in a composition such that the desired cement clinker can be obtained is calcined under normal firing conditions and cooled. Firing is usually performed using an electric furnace, a rotary kiln, or the like. As a firing method, for example, a first firing step in which a cement clinica raw material is heated and fired at a predetermined first firing temperature and a first firing time, and after the first firing step, a predetermined firing temperature is used. A raising step of raising the temperature to the second firing temperature over a predetermined raising time, and a second firing step of heating and firing at the second firing temperature and a predetermined second firing time after the raising step. , Including methods. The temperature and time of each step may be the conditions usually carried out, and the cement clinker can be produced by quenching the fired product.
Quenching is preferably 100 ° C./min or higher, more preferably 200 ° C./min or higher, and even more preferably 500 ° C./min or higher, from the viewpoint of the strength of mortar or the like using cement clinker.

[Cement composition]
The cement composition of the present invention contains the above-mentioned cement clinker and gypsum. Blaine specific surface area of the cement used in the present invention is preferably from 3000 cm ² / g or more 3400 cm ² / g or less, more preferably 3100 cm ² / g or more 3300 cm ² / g or less [gypsum]
The proportion of gypsum in the cement compositions of the present invention are preferably converted to SO ₃ content 0.5-2.5 wt%, more preferably from 1.0 to 1.8 wt%. By setting the ratio of gypsum to the above range, the drying shrinkage of the cement composition can be made appropriate, and the strength developed by the cement composition can be increased. The ratio of SO ₃ in gypsum can be measured according to JIS R 5202: 2010 “Chemical analysis method of Portland cement”. Ratio of the mass in terms of SO ₃ gypsum cement composition can be determined from the ratio of SO ₃ contained in the amount and gypsum plaster.
As the gypsum, any of anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum can be used.

<Other ingredients>
Fly ash, blast furnace slag, silica fume and the like can be further added to the cement composition of the present invention for adjusting fluidity, hydration rate or strength development. Further, an AE water reducing agent, a high-performance water reducing agent or a high-performance AE water reducing agent, particularly a polycal-based high-performance AE water reducing agent, can be added to the cement composition of the present invention.

[Mortar and concrete]
Cement milk can be made by mixing the cement composition of the present invention with water, mortar can be made by mixing with water and sand, and by mixing with sand and gravel. Can produce concrete. Further, when producing mortar or concrete from the above cement composition, blast furnace slag, fly ash or the like can be added.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
1. 1. Measurement and evaluation 1-1. Clinker Composition The chemical composition (content of each component) in the cement clinker of Examples and Comparative Examples is described in JIS R 5204: 2019 "Fluorescent X-ray analysis method of cement" and JCAS I-53: 2018 "trace amount in cement". It was measured according to "Method for quantifying components". The results are shown in Table 1.
The mineral composition was _{calculated from the mass ratios of CaO, SiO 2} , Al ₂ O ₃ and Fe ₂ O ₃ obtained by using the following Borg formula. The results are shown in Table 2.
C ₃ S = (4.07 × CaO)-(7.60 × SiO ₂ )-(6.72 × Al ₂ O ₃ )-(1.43 × Fe ₂ O ₃ )
C ₂ S = (2.87 x SiO ₂ )-(0.754 x C ₃ S)
C ₃ A = (2.65 x Al ₂ O ₃ )-(1.69 x Fe ₂ O ₃ )
C ₄ AF = 3.04 x Fe ₂ O ₃
Further, the value on the left side of the formula (1) was calculated using the content of each component obtained. The results are shown in Table 2.

1-2. EPMA measurement The cement clinker of Examples and Comparative Examples was pulverized to a particle size of about 1 to 2 mm to adjust the particle size. The obtained particles were embedded in an epoxy resin, and then the resin surface was mirror-polished. After mirror polishing, carbon vapor deposition was performed on the resin surface to prepare a sample for EPMA measurement.
An EPMA JXA-8200 manufactured by JEOL Ltd. was used as a measuring device, and the microstructure image of cement clinker particles on the mirror surface of the above sample was observed under the following conditions. In the histological image, each mineral was specified based on the characteristics of (a) to (d).
_{(A) C} 3 S: polygonal particles, light gray, several tens μm
(B) C ₂ S: Elliptical particles, dark gray, tens of μm
(C) C ₃ A: Amorphous tissue observed between silicate phases, dark gray, several μm to several tens of μm
(D) C ₄ AF: Amorphous structure observed between silicate phases, white, several μm to several tens of μm
Characteristic X-rays were analyzed for the above 4 minerals by 20 points for each mineral, acceleration voltage: 15 kV, irradiation current: 3.0 × ^10-8 A, beam diameter: about 1 μm, correction calculation method: Oxide-ZAF method. ..
Of these, C ₃ S adopted analysis points with an analysis value within the range of 2.7 <CaO content (%) / SiO _{2 content (%) <3.3.}
The resulting average value was taken as the chemical composition (mass%) in the C _{3 S.}

1-3. b-value The cement compositions of Examples and Comparative Examples were measured for b-value using a color tone meter (ZE-2000 type Nippon Denshoku Kogyo Co., Ltd.).

1-4.28 days Mortar strength (28d strength)
The 28-day mortar strength using the cement compositions of Examples and Comparative Examples was determined by using JIS R 5201 “Physical Test Method for Cement: 10.4 How to Make Specimens”, respectively. , 40 × 40 × 160 mm were placed in three metal molds, and after 24 hours, the mold was removed to prepare three mortar specimens each. The material was cured in water at 20 ° C. until the age of 28 days, and the compressive strength was measured according to JIS R 5201 “Physical test method for cement: 10.5 measurement”.

2. Preparation of cement composition 2-1. Cement clinker As raw materials for cement clinker, calcium carbonate (manufactured by Kishida Chemical Co., Ltd., reagent first grade, CaCO ₃ ), silicon dioxide (manufactured by Kanto Kagaku Co., Ltd., reagent first grade, SiO ₂ ), aluminum oxide (Kanto Kagaku (Kanto Kagaku) Made by Co., Ltd., Reagent 1st grade, Al ₂ O ₃ ), Iron oxide (III) (Kanto Chemical Co., Ltd., Reagent special grade, Fe ₂ O ₃ ), Basic magnesium carbonate (Kishida Chemical Co., Ltd., Reagent special grade) _{, 4MgCO 3 · Mg (OH)} 2 · 5H 2 O), sodium carbonate (manufactured by Kishida chemical Co., Ltd., special _grade, Na 2 _CO 3), potassium carbonate (Kanto chemical Co., Ltd., first grade _reagent, K 2 CO _3), calcium sulfate dihydrate (Kishida chemical Co., Ltd., first grade _reagent, CaSO 4 · _2H 2 O), titanium dioxide (Kanto chemical Co., Ltd., reagent express, _TiO 2), tricalcium phosphate (Kishida Chemical Co., Ltd., Reagent 1st grade, Ca ₃ (PO ₄ ) ₂ ), Manganese oxide (Kanto Chemical Co., Ltd., Deer 1st grade, MnO ₂ ), and Zinc oxide (Kanto Chemical Co., Ltd.) , Reagent special grade, ZnO) was used.

The raw materials mixed in different amounts were put into an electric furnace and fired at 1000 ° C. for 30 minutes. Then, the temperature was raised from 1000 ° C. to 1450 ° C. over 45 minutes, and further calcined at 1450 ° C. for 30 minutes. Then, the fired product was rapidly cooled by taking it out into the atmosphere to prepare cement clinker of Examples 1 to 6 and Comparative Example 1.

2-2. Preparation of the above-prepared cement clinker cement composition, the inner split converted to SO ₃ of 1.5% by weight of hemihydrate gypsum (Kanto Chemical Co., hemihydrate gypsum, model number: 07108-01 (calcined gypsum deer 1 Grade)) was blended. The formulation was pulverized with a ball mill so that the brain specific surface area value was in ^{the range of about 3200 ± 200 cm 2} / g to prepare cement compositions of Examples 1 to 6 and Comparative Examples 1 and 2.

2-3. Preparation of Mortar From the cement compositions of Examples and Comparative Examples, mortar was prepared according to JIS R 5201: 2015 “Physical test method for cement”. The obtained mortar was cast into three metal molds having a size of 40 mm × 40 mm × 160 mm, and after 24 hours, the mortar was demolded to prepare three specimens each.

Both Examples 1-6, while maintaining the content of _Al 2 _{O 3,} and less than -2.4500 value of left side of the equation (1), the content of _Al 2 _{O 3} in 3CaO · SiO ₂ (Al _{It is a cement clinker having 2} O ₃ _C ₃ S) of 1.000% by mass or more.
The b value of the cement composition prepared from the cement clinker was as small as 7.3 or less, and the yellowness could be suppressed. On the other hand, Comparative Example 1 was a cement clinker in which the value on the left side of the formula (1) was -2.4081, but the b value was 8.4, and the yellowish color was conspicuous.

The cement clinker of Example 2 had an Al ₂ O ₃ content of 5.26, and the value on the left side of the formula (1) was adjusted to -2.8488, but the b value was 7.2. I was able to suppress it.
In the cement clinker of Example 5, _{the content of MgO, MnO and ZnO was increased while further increasing the content of Al 2} O ₃ , and the value on the left side of the formula (1) was adjusted to -2.9494. However, the b value was 7.0 and the increase could be suppressed.
As described above, it was found that the increase in the b value can be suppressed by adjusting the value on the left side of the equation (1) to less than -2.4500.

Claims (4)

It _{contains Al 2} O ₃ , Fe ₂ O ₃ , MgO, MnO and ZnO, and the content of Al ₂ O ₃ is 2.00% by mass or more and 10.00% by mass or less, and the content of _{Fe 2} O ₃ Is 1.00% by mass or more and 10.00% by mass or less, the MgO content is 0.05% by mass or more and 5.0% by mass or less, and the MnO content is 0.01% by mass or more and 0. .80% by mass or less, and the ZnO content is 0.01% by mass or more and 0.0685% by mass or less.
A cement clinker that satisfies the following formula (1).

_{Wherein, W Al2 O3} represents the content of _Al 2 _{O 3} to cement clinker total amount _{(mass%), W Fe2O3} represents the content of _Fe 2 _{O 3} to cement clinker total amount _{(mass%), W MgO} cement clinker The content of MgO (% by mass) with _{respect to the total amount, W MnO} represents the content of MnO (% by mass) with _{respect to the total amount of cement clinker, and W ZnO} represents the content (% by mass) of ZnO with respect to the total amount of cement clinker. _{The ratio of 3CaO · SiO 2} calculated by the Borg formula is 50.0% by mass or more and 75.0% by mass or less.
_{The ratio of 2CaO · SiO 2} calculated by the Borg formula is 5.0% by mass or more and 25.0% by mass or less.
The first aspect of the present _{invention, wherein the total ratio of 3CaO / Al 2} O ₃ and 4 CaO / Al ₂ O ₃ / Fe ₂ O ₃ calculated by the Borg formula is 15.0% by mass or more and 22.0% by mass or less. Cement clinker. Cement clinker according to claim 2 _Al 2 _{O 3} content in the _{3CaO · SiO 2 (Al 2 O} 3 _C 3 S) is 1.000 mass% or more. A cement composition containing the cement clinker according to any one of claims 1 to 3 and gypsum.