JP7723489B2 - Cement mixture, its manufacturing method, and method for predicting quality of cement mixture - Google Patents

Description

The present invention relates to a cement mixture, a method for producing the same, and a method for predicting the quality of a cement mixture.

Coal ash generated at thermal power plants can be broadly divided into fly ash, which occurs when finely powdered burned coal turns into spherical particles as the temperature drops at the boiler outlet and is collected in an electrostatic precipitator, and clinker ash, which occurs when coal ash particles aggregate to form porous masses that fall and accumulate in the clinker hopper at the bottom of the boiler.
Fly ash can be used as a cement admixture, taking advantage of its spherical particle size of approximately 0.1 to 300 μm. On the other hand, clinker ash has a large maximum particle size of approximately 37.5 mm and is not spherical, making it difficult to use as a cement admixture or concrete admixture. It is mainly used as a roadbed material, a backfill material for quay walls, an earthwork material such as embankment material, and as a raw material for cement clinker.

Patent Document 1 describes a method for producing a cement composition that can effectively use a large amount of clinker ash as a cement admixture, comprising the following steps (A) and (B): (A) obtaining cement clinker having a cement mineral composition calculated using the Bogue formula of 55 to 70 mass% _C3S , 10 to 30 mass% _C2S , 7 to 15 mass% _C3A , and 7 to 15 mass% _C4AF ; and (B) adding 2 to 5 mass parts of gypsum dihydrate and 3 to 45 mass parts of clinker ash having a vitrification rate of 75 mass% or more to 100 mass parts of the obtained cement clinker, and mixing and grinding the mixture.
Patent Document 2 describes a hydraulic composition containing cement clinker, gypsum, and hearth ash as a cement composition that can use hearth ash without impairing the physical properties of the cement, characterized in that the hearth ash has a Blaine specific surface area of 3400±300 cm ² /g and a Hunter Lab lightness index L value of 41 or more as measured with a color difference meter.

Japanese Patent Application Laid-Open No. 2018-131361 Patent No. 6356057

Clinker ash has poorer fluidity and strength development than fly ash, and its quality varies widely, making it difficult to use as a cement admixture.
An object of the present invention is to provide a cement admixture containing clinker ash, which can produce a mixed cement having excellent fluidity and strength development.

As a result of intensive research to solve the above problems, the present inventors have found that the above object can be achieved by using a cement admixture containing clinker ash powder having a value of {Blaine's specific surface area ( ^cm2 /g)/(mullite content + quartz content + tridymite content) (mass%)} of 200 or more, and have completed the present invention.
That is, the present invention provides the following [1] to [8].
[1] A cement admixture containing clinker ash powder, wherein the value obtained from the following formula (1) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and tridymite in the clinker ash powder is 200 or more.
Blaine specific surface area/(mullite content + quartz content + tridymite content) (1)
(In the above formula (1), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).
[2] The cement admixture according to [1], wherein the clinker ash powder has a Blaine specific surface area of 4,000 cm ² /g or more.
[3] The Blaine specific surface area of the clinker ash powder and the CaO, MgO, Al ₂ O ₃ , and SiO ₂ contents of the clinker ash powder are used to obtain a value obtained from the following formula (2) of 1,200 or more. [4] The cement admixture according to [1] or [2].
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (2)
(In the above formula (2), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).

[4] A cement composition comprising the cement admixture according to any one of [1] to [3], ground cement clinker, and gypsum.
[5] A method for producing a cement mixture, comprising: a measuring step of measuring the contents of mullite, quartz, and tridymite in clinker ash, which is a raw material for a cement mixture; and a crushing step of crushing the clinker ash to obtain a cement mixture containing clinker ash powder, so that the value obtained from the following formula (3) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and tridymite in the clinker ash is 200 or more.
Blaine specific surface area/(mullite content+quartz content+tridymite content) (3)
(In the above formula (3), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).

[6] The method for producing a cement admixture according to [5], wherein in the measuring step, the contents of CaO, MgO, Al ₂ O ₃ , and SiO ₂ of the clinker ash are measured, and in the crushing step, the clinker ash is crushed so that the value obtained from the following formula (4) using the Blaine specific surface area of the clinker ash powder obtained by crushing the _clinker ash and the contents of CaO, MgO, Al ₂ O ₃ , and SiO 2 of the clinker ash is 1,200 or more.
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (4)
(In the above formula (4), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).
[7] The method for producing a cement mixture according to [5] or [6], comprising, between the measuring step and the crushing step, a sorting step of determining whether a total content of mullite, quartz, and tridymite in the clinker ash is 37% by mass or less, and using the clinker ash as a raw material for the cement mixture if the total content is 37% by mass or less, and not using the clinker ash as a raw material for the cement mixture if the total content exceeds 37% by mass.

[8] A quality prediction method for a cement mixture containing clinker ash powder, comprising: a sample preparation step of preparing two or more types of clinker ash powder for creating a prediction formula for a flow value ratio and a prediction formula for an activity index used in the quality prediction method; a first prediction formula creation step of creating a prediction formula for a flow value ratio by performing multiple regression analysis using a combination of the dependent variable and the independent variable for the two or more types of clinker ash powder, with the flow value ratio of the clinker ash powder as a dependent variable, and a numerical value obtained from the following formula (5) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and _tridymite of the clinker ash _powder as independent variables; and and a prediction step of obtaining predicted values of the _flow value ratio and activity index of the clinker ash powder contained in the cement mixture whose quality is to be predicted, using actually measured values of the Blaine specific surface area of the clinker ash powder contained in the cement mixture whose quality is to be predicted, and the contents of mullite, quartz, tridymite, CaO, MgO, Al ₂ O ₃ , and SiO ₂ of the clinker ash powder, and using the prediction formula for the flow value ratio and the prediction formula for the activity index, and predicting the quality of the cement mixture based on the predicted values.
The Blaine specific surface area/(the mullite content + the quartz content + the tridymite content) (5)
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (6)
(In the above formulas (5) and (6), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).

According to the present invention, even though clinker ash is used as a raw material for the cement admixture, the fluidity and strength development of the mixed cement containing the cement admixture can be improved.

FIG. 1 is a diagram showing the correlation between {Blaine specific surface area/(mullite content rate+quartz content rate+tridymite content rate)} and the flow value ratio of clinker ash powder. FIG. 1 is a diagram showing the correlation between the Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} of clinker ash powder and the activity index.

The cement admixture of the present invention is a cement admixture containing clinker ash powder, in which the value obtained from the following formula (1) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and tridymite in the clinker ash powder is 200 or more.
Blaine specific surface area/(mullite content + quartz content + tridymite content) (1)
(In the above formula (1), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).
In this specification, the units of the numerical values obtained from formulas (1) to (6) will be omitted. For example, the unit of the numerical value obtained from formula (1), "cm ² /(g·mass %)", will be omitted in this specification.
Here, clinker ash powder refers to coal ash in a red-hot state generated by the combustion of pulverized coal in a thermal power plant or the like, which aggregates to form porous lumps, which then fall into a water tank at the bottom of the boiler, where they are rapidly cooled and solidified, and are then crushed into lumps (clinker ash).

The numerical value obtained from the above formula (1) is 200 or more, preferably 220 or more, more preferably 250 or more, and particularly preferably 300 or more. If the numerical value is less than 200, the fluidity and strength development of the blended cement containing the cement admixture (hereinafter simply referred to as "blend cement") will decrease. There are no particular limitations on the upper limit of the numerical value, but from the perspective of ease of production, it is preferably 500, more preferably 450.

From the viewpoint of improving the strength development of the blended cement, the Blaine specific surface area of the clinker ash powder is preferably 3,000 cm ² /g or more, more preferably 3,500 cm ² /g or more, and particularly preferably 4,000 cm ² /g or more. The upper limit of the Blaine specific surface area is not particularly limited, but from the viewpoint of ease of production, it is preferably 8,000 cm ² /g, more preferably 6,500 cm ² /g, particularly preferably 5,500 cm ² /g, and particularly preferably 5,000 cm ² /g.

Furthermore, the value obtained from the following formula (2) using the Blaine specific surface area of the clinker ash powder and the contents of CaO, MgO, Al ₂ O ₃ , and SiO ₂ in the clinker ash powder is preferably 1,200 or more.
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (2)
(In the above formula (2), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).
The numerical value obtained from the above formula (2) is preferably 1,200 or more, more preferably 1,500 or more, even more preferably 2,200 or more, even more preferably 2,500 or more, and particularly preferably 2,600 or more. If the numerical value is 1,200 or more, the strength development of the blended cement can be further improved. The upper limit of the numerical value is not particularly limited, but from the viewpoint of ease of production, it is preferably 5,000, more preferably 4,000.

From the viewpoint of further improving strength development, the vitrification rate of the clinker ash powder (amount of amorphous phase in the clinker ash) is preferably 70 mass% or more, more preferably 75 mass% or more, even more preferably 78 mass% or more, and particularly preferably 80 mass% or more.
Moreover, from the viewpoint of providing sufficient strength development and promoting the utilization of clinker ash, the vitrification rate is preferably 60% by mass or more, more preferably 62 to 85% by mass, even more preferably 65 to 80% by mass, and particularly preferably 65 to 75% by mass.
Generally, it is believed that the higher the vitrification rate, the more improved the pozzolanic activity and the more useful the cement admixture is. In contrast, the cement admixture of the present invention has excellent fluidity and strength development not only when the vitrification rate is high (e.g., over 75% by mass) but also when a clinker ash powder with a low vitrification rate (e.g., 63 to 75% by mass) is used.
Considering that the effects of the present invention may be obtained even when the vitrification rate is low, the upper limit of the range of the vitrification rate is preferably less than 75 mass%, more preferably 73 mass%, even more preferably 71 mass%, and particularly preferably 67 mass%.

The cement mixture may contain materials other than clinker ash powder, such as fly ash, silica fume, and ground granulated blast furnace slag, as long as the effects of the present invention are not affected.
The proportion of clinker ash powder in the cement mixture is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

The cement composition of the present invention contains the above-mentioned cement admixture, ground cement clinker, and gypsum.
The cement clinker is not particularly limited, and examples thereof include various types of Portland cement clinkers such as ordinary 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. These may be used alone or in combination of two or more.
Among these, ordinary Portland cement clinker is preferred from the viewpoint of the strength development of the cement composition.
The method for producing the cement composition of the present invention is not particularly limited, and examples thereof include (i) a method of mixing pre-ground cement clinker, clinker ash powder, and pre-ground gypsum, and (ii) a method of mixing pre-ground cement (a mixture of clinker powder and gypsum) and clinker ash powder.
The gypsum is not particularly limited, and examples thereof include anhydrous gypsum, dihydrate gypsum, hemihydrate gypsum, and mixtures thereof.

The proportion of cement admixture in 100% by mass of the cement composition is preferably 1 to 40% by mass, more preferably 2 to 30% by mass, and particularly preferably 5 to 20% by mass. A proportion of 1% by mass or more can further promote the effective use of clinker ash. A proportion of 40% by mass or less can prevent a decrease in the fluidity and strength development of the cement composition.

The cement composition may contain other materials as needed, such as 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 various admixtures such as fly ash, silica fume, and ground granulated blast furnace slag.
In this specification, the hydraulic composition refers to a hardenable composition containing a cement composition and water, and includes the hydraulic composition in its pre-hardened form and its hardened form. Examples of the hydraulic composition include paste, mortar, and concrete.
Furthermore, when kneading water and pre-ground cement (a mixture of clinker powder and gypsum), clinker ash powder may be mixed to prepare a hydraulic composition in which the mixture of cement and clinker ash powder becomes the cement composition of the present invention.

An example of the method for producing the above-mentioned cement mixture includes a method including a measuring step of measuring the contents of mullite, quartz, and tridymite in clinker ash, which is a raw material for the cement mixture, and a crushing step of crushing the clinker ash to obtain a cement mixture containing clinker ash powder so that the value obtained from the following formula (3) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and tridymite in the clinker ash is 200 or more.
Blaine specific surface area/(mullite content+quartz content+tridymite content) (3)
(In the above formula (3), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).
Each step will be explained in detail below.

[Measurement process]
This step is a step for measuring the content of mullite, quartz, and tridymite, which are the mineral composition of clinker ash, which is a raw material for cement admixture.
The clinker ash, which is a raw material for the cement mixture, may be in the form of a lump or a powdery granular material that has been crushed in advance.
As a method for measuring the mineral composition, for example, a method of determining the mineral composition such as the content of mullite by applying X-ray diffraction (XRD)/Rietveld method to the clinker ash powder can be mentioned.
Furthermore, in this step, the contents of CaO, MgO, Al ₂ O ₃ , and SiO _2, which are the chemical composition of the clinker ash powder, may be measured. Methods for measuring the chemical composition include a method of measuring the chemical composition of the clinker ash powder using X-ray fluorescence analysis (XRF), and the chemical composition, such as the CaO content, is used as appropriate when pulverizing the clinker ash so as to obtain clinker ash powder that satisfies the numerical values obtained from a specific formula in the pulverization step described below.

[Crushing process]
This step is a step of pulverizing clinker ash to obtain a cement admixture containing clinker ash powder so that the value obtained from the following formula (3) using the Blaine specific surface area of the clinker ash powder obtained by pulverizing the clinker ash and the contents of mullite, quartz, and tridymite in the clinker ash is 200 or more.
Blaine specific surface area/(mullite content+quartz content+tridymite content) (3)
(In the above formula (3), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).

The numerical value obtained from the above formula (3) is 200 or more, preferably 220 or more, more preferably 250 or more, and particularly preferably 300 or more. If the numerical value is less than 200, the fluidity and strength development of the cement mixture will decrease. The upper limit of the numerical value is not particularly limited, but is preferably 500, more preferably 450, from the viewpoint of ease of production, etc.
The grinding means is not particularly limited, and examples thereof include a ball mill, a disk mill, and a vertical roller mill.

The following conditions may be added as further conditions for pulverization.
As an additional condition, from the viewpoint of obtaining a cement admixture with superior strength development and fluidity, the clinker ash is pulverized so that the value obtained from the following formula (4) using the Blaine specific surface area of the clinker ash powder obtained by pulverizing the clinker ash and the contents of CaO, MgO, Al ₂ O ₃ , and SiO ₂ in the clinker ash is 1,200 or more.
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (4)
(In the above formula (4), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).

The numerical value obtained from the above formula (4) is preferably 1,200 or more, more preferably 1,500 or more, even more preferably 2,200 or more, even more preferably 2,500 or more, and particularly preferably 2,600 or more. If the above numerical value is 1,200 or more, the strength development of the cement mixture can be further improved. There are no particular limitations on the upper limit of the above numerical value, but from the perspective of ease of production, etc., it is preferably 5,000, more preferably 4,000.

When the cement mixture contains materials other than the clinker ash powder, the other materials may be mixed as appropriate during or after the grinding process.
In addition, between the measurement step and the crushing step, a sorting step may be provided in which it is determined whether the total content of mullite, quartz, and tridymite in the clinker ash is 37% by mass or less, and if the total is 37% by mass or less, the clinker ash is used as a raw material for the cement mixture, and if the total exceeds 37% by mass, the clinker ash is not used as a raw material for the cement mixture.
If the total content of mullite, quartz, and tridymite in the clinker ash exceeds 37% by mass, it may be difficult to obtain clinker ash powder having a Blaine specific surface area such that the values obtained from the above formulas (3) and (4) are the desired values (for example, the value obtained from the above formula (3) is 200 or more and the value obtained from the above formula (4) is 1,200 or more). For this reason, it is preferable to use clinker ash having this total of 37% by mass or less as a raw material for cement admixtures. Clinker ash having this total of more than 37% by mass can be used as a roadbed material, a quay backfill material, an earthwork material such as an embankment material, or a raw material for cement clinker.

Furthermore, the quality of the clinker ash powder can be predicted using the Blaine specific surface area of the clinker ash powder contained in the cement mixture and the contents of mullite, quartz, tridymite, CaO, MgO, Al ₂ O ₃ , and SiO ₂ in the clinker ash powder, and the quality of the cement mixture can be predicted based on the prediction results.
Specifically, the method includes a sample preparation step, a first prediction formula creation step, a second prediction formula creation step, and a prediction step, which will be described later. Each step will be described in detail below.

[Sample preparation process]
This step is a step of preparing two or more types of clinker ash powder for creating a prediction formula for the flow value ratio and a prediction formula for the activity index used in the quality prediction method.
From the viewpoint of further improving the accuracy of prediction, the number of types of clinker ash powder (in other words, the number of combinations of data consisting of dependent variables and independent variables used in the first prediction equation creation step and the second prediction equation creation step described below) is 2 or more, preferably 5 or more, more preferably 10 or more, and particularly preferably 20 or more. From the viewpoint of reducing the effort required to prepare mortar specimens for obtaining actual measured values of the activity index of the clinker ash powder, the number is preferably 40 or less, more preferably 30 or less.

[First prediction equation creation step]
This step is a step of creating a prediction formula for the flow value ratio by performing multiple regression analysis using a combination of dependent variables and independent variables for two or more types of clinker ash powder, with the flow value ratio of the clinker ash powder as the dependent variable and a value obtained from the following formula (5) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and tridymite in the clinker ash powder as independent variables.
The Blaine specific surface area/(the mullite content + the quartz content + the tridymite content) (5)
(In the above formula (5), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).
By performing multiple regression analysis using a combination of data consisting of the above-mentioned dependent variables and the above-mentioned independent variables obtained from each of the two or more types of clinker ash powder prepared in the sample preparation step, a prediction formula can be obtained that can predict the flow value ratio with higher accuracy.

[Second prediction formula creation process]
This step is a step of creating a prediction formula for the activity index by performing multiple regression analysis using a combination of dependent variables and independent variables for two _{or more} types of clinker ash powder, with the activity index of the clinker ash powder as the dependent variable and the values obtained from the following formula (6) using the Blaine _specific surface area of the clinker ash powder and the contents of CaO, MgO, Al 2 O 3 , and SiO 2 of the clinker ash powder as independent variables.
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (6)
(In the above formula (6), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).

By performing multiple regression analysis using a combination of data consisting of the above-mentioned dependent variables and the above-mentioned independent variables obtained from each of the two or more types of clinker ash powder prepared in the sample preparation step, a prediction formula that can predict the activity index with higher accuracy can be obtained.
The activity index may be the 28-day activity index or the 91-day activity index specified in "JIS A 6201:2015 (fly ash for concrete)".
If it is desired to predict both the 28-day activity index and the 91-day activity index, prediction formulas for the activity index may be created for each of the 28-day activity index and the 91-day activity index.
The flow value ratio and activity index of the clinker ash powder can be measured in accordance with "JIS A 6201:2015 (fly ash for concrete)".

[Prediction process]
This process uses the Blaine specific surface area of the clinker ash powder contained in the cement mixture whose quality is to be predicted, and the actual measured values of the contents of mullite, quartz, tridymite, CaO, MgO, Al ₂ O ₃ , and SiO ₂ in the clinker ash powder, as well as the above-mentioned flow value ratio prediction formula and activity index prediction formula to obtain predicted values of the flow value ratio and activity index of the clinker ash powder contained in the cement mixture whose quality is to be predicted, and predicts the quality of the cement mixture based on the predicted values.
From the viewpoint of predicting the quality of a cement mixture with higher accuracy, the proportion of clinker ash powder contained in the cement mixture whose quality is to be predicted is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[Materials used]
(1) Clinker ash A to F (each with different qualities)
The chemical and mineral compositions of clinker ashes A to F are shown in Tables 1 and 2.
The chemical composition of the clinker ash was measured using XRF, and the mineral composition of the clinker ash was determined by an external standard method based on the XRD/Rietveld method. The X-ray fluorescence analyzer used was a Rigaku Corporation product name "ZSX Primus II," and the chemical composition was measured using the calibration curve (coal ash) method. The X-ray diffraction analyzer used was a Bruker A.X. product name "D8ADVANCE A25," and the Rietveld analysis software used was a Bruker A.X. product name "TOPAS Ver. 6.0." The X-ray diffraction measurement was performed under the following conditions: CuKα radiation, tube voltage 50 kV, tube current 40 mA, scan range 5° to 65° (2θ), step width 0.0234, scan speed 0.13 sec/step, and "special grade reagent calcium carbonate" manufactured by Kanto Chemical Co., Ltd. was used as the external standard sample. The clinker ash minerals analyzed were mullite, quartz, tridymite, anorthite, cristobalite, hematite, magnetite, calcite, hemihydrate gypsum, and anhydrous gypsum, and the vitrification rate was also measured using the external standard method.

[Examples 1 to 9, Comparative Examples 1 to 11]
The types of clinker ash shown in Table 3 were pulverized using a ball mill until they reached the Blaine specific surface areas shown in Table 3 (shown as "Blaine" in Table 3), to obtain clinker ash powders.
From the Blaine specific surface area, mineral composition, and chemical composition of the clinker ash powder, {Blaine specific surface area/(mullite content + quartz content + tridymite content)} (hereinafter sometimes abbreviated as "Bl/MQT") and [Blaine specific surface area x {(CaO content + _MgO content + _Al2O3 content)/ _SiO2 content}] (hereinafter sometimes abbreviated as "Bl x CMA/S") were calculated.
The values of the mineral composition and chemical composition of the clinker ash powder were the same as those of the clinker ash (before pulverization), and these values were the same before and after pulverization.
In addition, the flow value ratio, 28-day activity index, and 91-day activity index of the clinker ash powder were measured in accordance with "JIS A 6201:2015 (fly ash for concrete)".
The results are shown in Table 3.

From Table 3, it can be seen that the clinker ash powders of Examples 1 to 9 (Bl/MQT values: 200 or more) had flow value ratios of 95 to 98, 28-day activity indices of 80 to 100, and 91-day activity indices of 90 to 105. From this, it can be seen that the clinker ash powders of Examples 1 to 9 meet the quality of fly ash type II (flow value ratio: 95 or more, 28-day activity index: 80 or more, 91-day activity index: 90 or more) specified in "JIS A 6201:2015 (fly ash for concrete)."
In particular, the clinker ash powders (Examples 2 to 9) with a Blaine specific surface area of 4,000 cm ² /g or more had a 28-day activity index of 85 to 100 and a 91-day activity index of 96 to 105, and it can be seen that these clinker ash powders meet the quality generally considered to be good quality for Type II fly ash (28-day activity index: 85 or more, 91-day activity index: 95 or more).
Furthermore, it can be seen that the 28-day activity index (90 to 100) and 91-day activity index (101 to 105) of the clinker ash powder (Examples 6, 7, and 9) having a Bl×CMA/S of 2,500 or more satisfy the quality of Type I fly ash (28-day activity index: 90 or more, 91-day activity index: 100 or more) specified in "JIS A 6201:2015 (fly ash for concrete)."
In addition, although the vitrification rate of the clinker ash in Example 7 is a low value of 64.5% by mass, it is clear that the quality of fly ash type II specified in "JIS A 6201:2015 (fly ash for concrete)" is met.

On the other hand, it can be seen that the flow value ratios of the clinker ash powders of Comparative Examples 1 to 11 (where the Bl/MQT values are less than 200) are 89 to 93. From this, it can be seen that the clinker ash powders of Comparative Examples 1 to 11 do not satisfy the quality of Type II fly ash (flow value ratio: 95 or more) specified in "JIS A 6201:2015 (fly ash for concrete)."
A large flow ratio indicates that the blended cement has excellent fluidity, and a large activity index indicates that the blended cement has excellent strength development.

[Example 10]
Twenty-one types of clinker ash powder samples were prepared, and the mineral composition (contents of mullite, quartz, and tridymite), chemical composition (contents of CaO, MgO, Al ₂ O ₃ , and SiO ₂ ), Blaine specific surface area, flow value ratio, and actual values of the 28-day activity index and 91-day activity index were measured for each sample.
Furthermore, based on the measurement results, the values of Bl/MQT and Bl×CMA/S were calculated.
The flow value ratio of the clinker ash powder obtained from each sample was used as the dependent variable, and the Bl/MQT value was used as the independent variable. A multiple regression analysis was performed using data (21 items) consisting of combinations of dependent and independent variables, and the following multiple regression equation (coefficient of determination ^R2 = 0.7931) was obtained as a prediction equation for the flow value ratio.
Flow value ratio = 0.0262 × (Bl/MQT) + 88.468
From the above multiple regression equation, it is clear that there is a high correlation between Bl/MQT and the flow value ratio, and that the flow value ratio can be predicted with high accuracy using the above multiple regression equation (prediction equation).
The relationship between Bl/MQT and the flow value ratio is shown in FIG.

In addition, a multiple regression analysis was performed using data (21 items) consisting of combinations of dependent and independent variables, with the 28-day activity index of the clinker ash powder obtained from each sample as the dependent variable and the value of Bl × CMA/S as the independent variable, to obtain the following multiple regression equation (coefficient of determination ^R2 = 0.8038) as a prediction formula for the 28-day activity index.
28-day activity index = 0.0086 x (Bl x CMA/S) + 69.949
Furthermore, a multiple regression analysis was performed using data (21 items) consisting of combinations of dependent and independent variables, with the 91-day activity index of the clinker ash powder obtained from each sample as the dependent variable and the value of Bl × CMA/S as the independent variable, to obtain the following multiple regression equation (coefficient of determination ^R2 = 0.8397) as a prediction formula for the 91-day activity index.
91-day activity index = 0.0068 x (Bl x CMA/S) + 82.759
From the above multiple regression equation, it is clear that there is a high correlation between Bl×CMA/S and the activity index, and that the activity index can be predicted with high accuracy using the above multiple regression equation (prediction equation).
The relationship between Bl×CMA/S and the 28-day activity index or 91-day activity index is shown in FIG.

Claims (7)

A cement mix comprising clinker ash powder,
The clinker ash powder has a flow value ratio of 95% or more, a 28-day activity index of 85% or more, and a 91-day activity index of 96% or more, as measured in accordance with "JIS A 6201:2015 (fly ash for concrete)",
The clinker ash powder has a Blaine specific surface area of 4,000 cm ² /g or more;
A cement admixture characterized in that the value obtained from the following formula (1) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and tridymite in the clinker ash powder is 200 or more.
Blaine specific surface area/(mullite content + quartz content + tridymite content) (1)
(In the above formula (1), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %). 2. The cement admixture according to claim 1, wherein the value obtained from the following formula (2) using the Blaine specific surface area of the clinker ash powder and the contents of CaO, MgO, Al ₂ O ₃ , and SiO ₂ of the clinker ash powder is 1,200 or more.
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (2)
(In the above formula (2), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %). A cement composition comprising the cement admixture according to claim 1 or 2 , ground cement clinker, and gypsum. A method for producing the cement composition according to claim 3 , comprising the following steps (a) or (b):
(a) mixing the cement admixture, the pulverized cement clinker, and the gypsum to prepare the cement composition; (b) mixing the cement admixture, the pulverized cement clinker, and the gypsum to prepare the cement composition. a measuring step of measuring the contents of mullite, quartz, and tridymite in clinker ash, which is a raw material for cement mixtures;
a grinding step of grinding the clinker ash to obtain a cement admixture containing the clinker ash powder so that the value obtained from the following formula (3) using the Blaine specific surface area of the clinker ash powder obtained by grinding the clinker ash and the contents of mullite, quartz, and tridymite in the clinker ash is 200 or more and the Blaine specific surface area of the clinker ash powder is 4,000 cm ² /g or more ;
A method for producing a cement mixture, comprising, between the measuring step and the crushing step, a sorting step of determining whether the total content of mullite, quartz, and tridymite in the clinker ash is 37% by mass or less, and using the clinker ash as a raw material for the cement mixture if the total content is 37% by mass or less, and not using the clinker ash as a raw material for the cement mixture if the total content exceeds 37% by mass .
Blaine specific surface area/(mullite content+quartz content+tridymite content) (3)
(In the above formula (3), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %). In the measuring step, the contents of CaO, MgO, Al ₂ O ₃ , and SiO ₂ of the clinker ash are measured;
6. The method for producing a cement mixture according to claim 5, wherein in the grinding step, the clinker ash is ground so that the value obtained from the following formula ( 4 ) using the Blaine specific surface area of the clinker ash powder obtained by grinding the clinker ash and the contents of CaO, MgO, Al ₂ O ₃ , and SiO ₂ of the clinker ash is 1,200 or more.
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (4)
(In the above formula (4), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %). A method for predicting the quality of a cement mix containing clinker ash powder, comprising:
a sample preparation step of preparing two or more types of clinker ash powder for creating a prediction formula for the flow value ratio and a prediction formula for the activity index used in the quality prediction method;
a first prediction formula creation step of creating a prediction formula for the flow value ratio by performing multiple regression analysis using a combination of the dependent variable and the independent variable of the two or more types of clinker ash powder, with the flow value ratio of the clinker ash powder as a dependent variable, and a numerical value obtained from the following formula (5) using the Blaine specific surface area of the clinker ash powder and the contents of mullite, quartz, and tridymite in the clinker ash powder as independent variables;
a second prediction formula creation step of creating a prediction formula for the activity index by performing multiple regression analysis using a combination of the dependent variable and the independent variables of the _{two or more} types of clinker ash powder, with the activity index of the clinker ash powder as a dependent variable and a value obtained from the following formula (6) using the Blaine specific surface area of the clinker ash powder and the contents of CaO, MgO, Al 2 O 3 , and SiO 2 of the clinker ash powder as independent variables;
a _prediction step of obtaining predicted values of the flow value ratio and activity index of the clinker ash powder contained in the cement mixture whose quality is to be predicted, using actual measured values of the Blaine specific surface area of the clinker ash powder contained in the cement _mixture whose quality is to be predicted, and the contents of mullite, quartz, _tridymite , CaO, MgO, Al 2 O 3 , and SiO 2 in the clinker ash powder, as well as the prediction formula for the flow value ratio and the prediction formula for the activity index, and predicting the quality of the cement mixture based on the predicted values.
The Blaine specific surface area/(the mullite content + the quartz content + the tridymite content) (5)
The Blaine specific surface area × {(the CaO content + the MgO content + the Al ₂ O ₃ content) / the SiO ₂ content} (6)
(In the above formulas (5) and (6), the unit of the Blaine specific surface area is cm ² /g, and the unit of the content is mass %).