KR102255380B1 - Cement composition and method for preparing cement composition - Google Patents

Abstract

It provides a cement composition capable of ensuring the strength when used for concrete by evaluation by mortar, and capable of controlling the quality of concrete by evaluation by mortar. The cement composition of the present invention is including a clinker with gypsum and limestone, and the lattice volume of Cal site of the limestone, 366.76Å ³ or more 368.00Å ³ below.

Description

Cement composition and method for preparing cement composition

The present invention relates to a cement composition and a method for producing the cement composition, and in particular to a cement composition using Portland cement.

In order to guarantee the quality of a building built using a structure manufactured using mortar or concrete, it is necessary that the cement composition used for mortar or concrete exhibits high strength. For this reason, conventionally, various cement compositions exhibiting high strength have been developed.

Among such cement compositions, a cement composition in which the strength expressed by the cement composition is increased by adjusting the particle size distribution and specific surface area of the cement composition is known. For example, in the cement-containing powder composition described in Patent Document 1, the specific surface area of the cementitious material is 1500 to 3300 cm ² /g, and the residual amount of the 100 μm sieve is 0.5 to 40 mass%, so that the cement-containing powder composition is The intensity to be expressed is increased.

Japanese Unexamined Patent Publication No. 2014-166927

In Patent Document 1, the strength exhibited by the cement composition is evaluated using a specimen made of mortar. In addition, as long as the cement composition exhibits high strength in the evaluation by mortar, it is said that the cement composition also exhibits high strength in concrete. However, there has been a problem that the cement composition, which is considered to exhibit high strength in the evaluation by mortar, cannot always exhibit high strength when used for concrete.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a cement composition capable of ensuring strength when used for concrete by evaluation by mortar, and capable of controlling the quality of concrete by evaluation by mortar. It is done.

As a result of intensive research conducted by the present inventors, the lattice volume of calcite of limestone used in the cement composition and the strength ratio of concrete/mortar (the strength of the specimen of concrete made of the cement composition, and the specimen of mortar made of the same cement composition) It was found that there was a strong correlation between the ratio of the intensity of In addition, in the case of using limestone having a specific calsite lattice volume, the concrete/mortar strength ratio tends to be high even in the case of the same degree of mortar strength, and furthermore, it has been found that the variation in concrete strength decreases. Came to complete.

In order to solve the above problems, the present invention provides the following [1] to [5].

1 and clinker, gypsum, and include limestone, and the lattice volume of Cal site of the limestone, 366.76Å ³ or more than ³ 368.00Å cement composition.

[2] In the clinker, _{the ratio of 3CaO·SiO 2} calculated by the Vogue formula is 50 to 75 mass%, and _{the ratio of 2CaO·SiO 2} calculated by the Vogue formula is 8 to 30 mass%, calculated by the Vogue formula The cement composition according to [1], wherein the proportion of the total of 3CaO·Al ₂ O ₃ and 4CaO·Al ₂ O _3· Fe ₂ O _{3 is 15 to 25 mass%.}

[3] [1] or [2], wherein the particle size distribution by the microtrack method is 18.0% or more and 26.0% or less, and the proportion of particles 22 or more and less than 44 μm is 31.8% or more and 38.0% or less, The cement composition described in ].

[4] The cement composition according to any one of [1] to [3], wherein the blast specific surface area is 3200 cm ² /g or more and 3800 cm ^{2 /g or less.}

[5] A method for producing a cement composition comprising the step of crushing and mixing clinker, gypsum, and ^{limestone having a lattice volume of 366.76Å 3} or more and 368.00Å ^{3 or less.}

Advantageous Effects of Invention According to the present invention, strength when used for concrete can be ensured by evaluation by mortar. Moreover, since the concrete strength can be estimated with high precision from the evaluation by mortar, quality control of concrete can be performed appropriately.

1 is a graph showing the relationship between mortar strength and concrete strength.

Hereinafter, the cement composition of the present invention will be described in detail. In addition, the notation of the numerical range "AA to BB" in this specification means "AA or more and BB or less".

[Cement composition]

The cement composition of the present invention is a clinker and gypsum, and the volume of the lattice contains the limestone, and Cal site of limestone, 366.76Å ³ or more 368.00Å ³ below.

Specifically, the cement composition of the present invention is usually Portland cement, crude steel Portland cement, or ultra-rough steel Portland cement.

Hereinafter, each component of the cement composition will be described.

〔Clinker〕

The clinker used in the cement composition of the present invention is 3CaO·SiO ₂ (abbreviation: C ₃ S), 2CaO·SiO ₂ (abbreviation: C ₂ S), 3CaO·Al ₂ O ₃ (abbreviation: C ₃ A), and It includes 4CaO·Al ₂ O _3· FeO ₃ (abbreviation: C ₄ AF). Cement clinker is the gap _{between the main minerals of allite (C 3} S) and bellite (C ₂ S), and the aluminate phase (C ₃ A) and ferrite phase (C _{4 AF) present between the crystals of the main mineral.} It consists of prizes and the like.

The clinker used in the cement composition of the present invention is not particularly limited as long as it meets the quality specified in JIS R 5210:2009 "Portland Cement", but _{the ratio of 3CaO·SiO 2} calculated by the Vogue formula is 50 to 75 mass. _{%, and the ratio of 2CaO·SiO 2} calculated by the Vogue formula is 8 to 30% by mass, and the ratio of the sum of _{3CaO·Al 2} O ₃ and 4CaO·Al ₂ O _3· FeO _{3 calculated by the Vogue formula is 15~} It is preferably 25% by mass.

<Clinker manufacturing process>

The clinker of the present invention can be manufactured as follows, for example. As the clinker raw material, as long as it contains Ca, Si, Al, Fe, or the like, any form of elemental substance, oxide, carbonate, or the like can be used, and a mixture thereof can be used. Examples of 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, fly ash, and the like. The mixing ratio of such clinker raw materials is not particularly limited as long as clinker satisfying the Vogue formula value can be produced, and the raw material formulation may be determined so as to have a component composition corresponding to the target Vogue formula value.

Then, the clinker raw material mixed with the composition from which the target clinker is obtained is fired and cooled under the following firing conditions. The 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 the clinker raw material is heated at a predetermined first firing temperature and a first firing time to perform firing, and after the first firing step, a predetermined second firing temperature is obtained from the first firing temperature. A method including a temperature rising step of raising the temperature to the firing temperature by taking a predetermined temperature rising time, and a second firing step of heating by heating at a second firing temperature and a predetermined second firing time after the temperature raising step to perform firing. For example, in the case of using an electric furnace, after heating the clinker raw material at a firing temperature of 1000°C (first firing temperature) for 30 minutes (first firing time) and firing (first firing step), 1450°C (first firing temperature) 2 After heating up to the firing temperature) over 30 minutes (heating time) (heating step), heating at 1450°C for 15 minutes (second firing time) to perform firing (second firing step), and then quenching the fired product. By doing so, clinker can be manufactured.

〔gypsum〕

The cement composition of the present invention contains gypsum. Moreover, the gypsum in this invention contains half-water gypsum. The gypsum in the present invention may further contain anhydrous gypsum and/or dihydrated gypsum.

It is preferable that it is 0.8 mass% or more, and, as for the ratio of _{the mass of the gypsum converted into SO 3} with respect to the mass of a cement composition, it is more preferable that it is 1.0 mass% or more. By setting the proportion of gypsum in the above range, the drying shrinkage of the cement composition can be appropriately performed, and the long-term strength that the cement composition develops (for example, the strength of concrete at 28 days of age) can be increased. . The ratio of SO ₃ in gypsum can be measured in accordance with JIS R 5202:2010 "Method for Chemical Analysis of Portland Cement". The ratio of the mass _{of gypsum in terms of SO 3} in the cement composition can be obtained from _{the amount of gypsum and the ratio of SO 3 contained in the gypsum.}

〔Lime stone〕

Limestone of the invention, the lattice volume of the site to the requirements that Cal 366.76Å ³ or more 368.00Å ³ or less. In the present invention, the lattice volume of Calcite is a value calculated from the lattice constant obtained by performing X-ray diffraction measurement of limestone and Rietveld analysis of the diffraction pattern.

Limestone is mainly added to the cement composition for the purpose of improving the fluidity and durability and strength of mortar or concrete. In general, limestone contains trace components, and the trace components are dissolved in the lattice of calcium carbonate, which is the main component of limestone, so that the lattice volume of Calcite changes. The main trace component is MgO, and since magnesium has an ionic radius smaller than that of calcium, the lattice volume of Calcite tends to decrease depending on the content of MgO. The content of trace components in limestone differs depending on the location of the limestone, and therefore, the lattice volume of Calcite also differs depending on the location of the limestone.

It is preferable that the lattice volume of calcite of limestone is 366.82 Å ^{3 or more.} In particular, it is preferable that the calcite lattice volume of limestone is 366.90 Å ^{3 or more.}

The effect of using limestone whose lattice volume of calcite is in the above range will be described later.

The proportion of limestone in the cement composition is not particularly limited as long as it meets the quality specified in JIS R 5210:2009 "Portland cement", but the proportion of limestone is preferably 1.0% by mass or more, and more preferably 1.5% by mass or more. Do. When limestone is in the above ratio, it is possible to improve the long-term strength that the cement composition develops (for example, the strength of concrete at 28 days of age), and the fluidity of the cement composition is improved, and workability when made into concrete Can be done well. Moreover, by setting it as the said ratio, as a result of pulverizing and mixing limestone, gypsum, and clinker in the manufacture of a cement composition, the particle size distribution in a cement composition can be adjusted suitably. The proportion of limestone in the cement composition can be determined by the amount of limestone added.

[Other ingredients]

To the cement composition of the present invention, fly ash, blast furnace slag, silica fume, or the like can be further added for control of fluidity, hydration rate, or strength development. Further, by adding 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, to the cement composition of the present invention, the fluidity and strength of concrete can be further improved.

[Method for producing cement composition]

Clinker, gypsum, and ^{limestone having a lattice volume of 366.78Å 3} or more and 368.00Å ³ or less are pulverized and mixed. In this step, it is preferable to blend clinker, gypsum, and limestone in a predetermined ratio to pulverize the blend. The pulverization is carried out by a known method so as to have a desired blast specific surface area. As a pulverization method, there is a method using a ball mill which is a common pulverizer.

Alternatively, in the present invention, clinker, gypsum, and limestone (calcite volume of 366.76 ^{Å 3} or more and 368.00 ^{Å 3} or less) pulverized in advance are mixed in a predetermined ratio so that the specific surface area of the blin after mixing becomes a desired value, cement It is also possible to use a composition.

[Particle size distribution of cement composition]

The cement composition of the present invention preferably has a particle size distribution of 11 μm or more and less than 22 μm, 18.0% or more and 26.0% or less, and 31.8% or more and 38.0% or less of the particles 22 μm or more and less than 44 μm. . In the present invention, there is a volume grating in the Cal site can easily adjust the particle size distribution of the cement composition by using a ^third or more ³ or less 368.00Å 366.76Å limestone in the above-described range.

The particle size distribution is more preferably, the proportion of particles having 11 μm or more and less than 22 μm is 21.0% or more and 24.0% or less, and the proportion of particles that are 22 μm or more and less than 44 μm is 32.0% or more and 35.0% or less.

In addition, the measurement of the particle size distribution by the microtrack method is carried out in accordance with JIS R 1629 "Method of measuring particle size distribution by laser diffraction/scattering method of fine ceramics raw materials".

[Blaine specific surface area of cement composition]

It is preferable that the blast specific surface area of the cement composition of the present invention is 3200 cm ² /g or more and 3800 cm ^{2 /g or less.} When the specific surface area of the cement composition is within the above range, the long-term strength (for example, the strength of concrete at the age of 28) can be further improved. Moreover, the fluidity|liquidity of a cement composition can be improved. In addition, the Blaine specific surface area is a specific surface area measured by the Blaine method in accordance with JIS R 5201:2015 "Physical Test Method of Cement".

[Mortar and concrete]

Cement milk can be produced by mixing the cement composition of the present invention with water, mortar can be produced by mixing with water and sand, and concrete can be produced by mixing with sand and gravel. Further, when producing mortar or concrete from the cement composition, blast furnace slag or fly ash may be added.

〔Concrete/mortar strength ratio〕

The value of the ratio (concrete/mortar strength ratio) between the strength of the concrete specimen made from the cement composition and the strength of the mortar specimen made from the same cement composition is the closer to 1, the more preferable. Cement compositions of the present invention, the lattice volume of Cal site 366.76Å ³ or higher By using the 368.00Å ³ or less limestone to the cement composition is a concrete / mortar intensity ratio of 0.74 or more. This is a high value compared to the case of using limestone outside the above range. That is, the cement composition of the present invention can secure concrete strength by evaluation by mortar.

In addition, the cement composition of the present invention can reduce the variation of the concrete/mortar strength ratio. That is, the error between the concrete strength (estimated value) and the measured value estimated from the mortar strength is reduced. For this reason, concrete strength can be estimated with high precision by evaluation with mortar. Therefore, the cement composition of the present invention can properly control the quality of concrete by evaluation by mortar.

In addition, "mortar strength" in this invention is 28-day mortar compressive strength measured in conformity with JIS R 5201:2015 "Physical test method of cement". The "concrete strength" in the present invention is the 28-day compressive strength of concrete measured in accordance with JIS A 1108 "Test method for compressive strength of concrete".

As described above, embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and includes all aspects included in the concept and claims of the present invention, and variously modified within the scope of the present invention. can do.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is by no means limited to the following examples.

1. Evaluation method

1-1. Calcite's lattice volume

For the limestones of Examples and Comparative Examples, a powder X-ray diffraction apparatus (manufactured by Panalitical Co., Ltd., X'Part Powder) was used, and the measurement conditions were determined, measurement range: 2θ = 10 to 70°, step size: 0.017°, scan Speed: 0.1012°/s, voltage: 45 kV, current: 40 mA, X-ray diffraction measurement was performed to obtain an X-ray diffraction profile.

Using the crystal structure analysis software (manufactured by Panalitical, X'Part High Score Plus version 2.1b) provided in the powder X-ray diffraction apparatus, analysis by Rietveld method was performed, and the grating volume was calculated from the obtained lattice constant. Calculated. In the Rietveld analysis, ICDD number 50586 was used as the initial value of the basic crystal structure data.

1-2. Clinker composition

_{The mass ratios of CaO, SiO 2} , Al ₂ O ₃ and Fe ₂ O ₃ in the clinker in the cement compositions of Examples and Comparative Examples were calculated according to JIS R 5204:2019 "Method of Fluorescent X-ray Analysis of Cement". . Using the calculation result, each composition of clinker was calculated from the following Vogue equation.

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×SiO ₂ )-(0.754×C ₃ S)

C ₃ A=(2.65×Al ₂ O ₃ )-(1.69×Fe ₂ O ₃ )

C ₄ AF=3.04×Fe ₂ O ₃

1-3. The ratio of the mass _{of gypsum in terms of SO 3} in the cement composition

_{The ratio of the mass of gypsum in terms of SO 3} in the cement compositions of Examples and Comparative Examples was determined from the blending amount of gypsum and _{the ratio of SO 3 contained in the gypsum.} The ratio of SO ₃ in gypsum was measured in accordance with JIS R 5202:2010 "Method for Chemical Analysis of Portland Cement".

1-4. Blaine specific surface area

Blaine specific surface area values of the cement compositions of Examples and Comparative Examples were measured in accordance with JIS R 5201:2015 "Physical Test Method of Cement".

1-5. Particle size distribution

The particle size distribution of the cement compositions of Examples and Comparative Examples was measured by the microtrack method in accordance with JIS R 1629 "Method for measuring particle size distribution by laser diffraction/scattering method of fine ceramics raw materials". As a measuring device, MT3300EXII manufactured by Microtrac Bell Corporation was used. Ethanol was used as the dispersion medium, and dispersion was performed for 30 seconds with an ultrasonic device before measurement.

1-6. Mortar strength

According to JIS R 5201:2015 "Physical test method of cement: 10.5 measurement", the compressive strength of the mortar was measured.

1-7. Concrete strength

The compressive strength of concrete on 28 days was measured in accordance with JIS A 1108 "Test Method for Compressive Strength of Concrete".

2. Preparation of cement composition

2-1. Clinker

As clinker raw materials, silicon dioxide (manufactured by Kanto Chemical Co., Ltd., reagent grade 1, SiO ₂ ), iron (III) oxide (manufactured by Kanto Chemical Co., Ltd., reagent express, Fe ₂ O ₃ ), calcium carbonate (group Shida Chemical Co., Ltd. product, reagent first grade, CaCO ₃ ), aluminum oxide (Kanto Chemical Co., Ltd. product, reagent first grade, Al ₂ O ₃ ), basic magnesium carbonate (Kishida Chemical Co., Ltd. product, Reagent limited express, about 4MgCO ₃ Mg(OH) ₂ 5H ₂ O), sodium carbonate (manufactured by Kishida Chemical Co., Ltd., anhydrous, limited express, Na ₂ CO ₃ ) and tricalcium phosphate (Kishida Chemical Co., Ltd. ) Agent, reagent grade 1, Ca ₃ (PO ₄ ) ₂ ) was used.

The clinker raw material blended by appropriately changing the blending amount was put into an electric furnace, fired at 1000°C for 30 minutes, then heated from 1000°C to 1450°C over 30 minutes, and further fired at 1450°C for 15 minutes. Thereafter, the fired product was rapidly cooled by taking it out of the air to prepare a clinker used in each of the Examples and Comparative Examples.

2-2. Preparation of cement composition

The cement clinker and gypsum produced above (half gypsum (half gypsum manufactured by Kanto Chemical Co., Ltd., model number: 07108-01 (CICA) 1st grade) and Isu gypsum (manufactured by Noritake Company Limited, model number) : Quick gypsum No. A)) and limestone are mixed. Then, the blend was pulverized with a ball mill so that the specific surface area value of the blast ^{was in the range of about 3000 to about 3800 cm 2} /g to prepare cement compositions of each of the Examples and Comparative Examples.

_{In addition, the ratio of the mass of the gypsum converted into SO 3} in the cement compositions of Examples and Comparative Examples was changed between the respective cement compositions by changing the amount of the gypsum.

As the limestones of Examples and Comparative Examples, a plurality of kinds of limestones having different production areas and lots were prepared.

2-3. Production of mortar specimens

Mortars prepared from the cement compositions of Examples and Comparative Examples were poured into three metal frames of 40 mm × 40 mm × 160 mm, respectively, and demolded after 24 hours to prepare three mortar specimens. Thereafter, it was cured in water at 20° C. until the age of 28 days to obtain mortar specimens of each of the Examples and Comparative Examples.

2-4. Preparation of concrete specimen

In the blending ratios shown in Table 1, the cement compositions of Examples and Comparative Examples, sand (Ibigawa river sand, particle diameter 25 to 5 mm), gravel (crushed stone from Nishijima, particle diameter 5 mm or less), AE water reducing agent (BASF Pojolis Co., Ltd. ) Agent, brand name: master polyhyde 15S) and water were homogeneously mixed using a fan-type forced mixer (manufactured by Okasan Kiko Co., Ltd., model number: STR-N2 8H) to prepare concrete. Each of the obtained concrete was poured into three metal frames of φ 100 mm × 200 mm in height, and demolded after 24 hours to produce three concrete specimens. Thereafter, it was cured in water at 20° C. until the age of 28 days to obtain concrete specimens of each of the Examples and Comparative Examples.

[Table 1]

Table 2 shows the results of using limestones with different lattice volumes of Calsite by making the Clinker's Borg's formula value, gypsum amount, limestone amount, and powdery the same. In addition, in Table 2, “11 to 22 μm” means that the particle diameter is 11 μm or more and less than 22 μm, and “22 to 44 μm” means that the particle diameter is 22 μm or more and less than 44 μm.

[Table 2]

From the results of Table 2, the larger the lattice volume of Calsite, the higher the value of the concrete/mortar strength ratio (σc/σm) and the smaller the deviation. From these results, it can be said that the lattice volume of Calcite affects the concrete/mortar strength ratio. In addition, the larger the lattice volume of Calcite, the relatively larger the proportion of particles that are 22 μm or more and less than 44 μm, and particles that are 11 μm or more and less than 22 μm. There was a tendency that the ratio of was relatively small. From this, it was thought that there was a correlation between the lattice volume of Calcite and the particle size distribution in the cement composition.

In Table 3, the results of Examples 4 to 19 and Comparative Examples 4 to 12 are shown. In Fig. 1, the relationship between the mortar strength and concrete strength of Examples 1 to 19 and Comparative Examples 1 to 12 is shown.

[Table 3]

According to Tables 2 and 3, the concrete/mortar strength ratio in all of the examples was 0.74 or more, resulting in a higher result than that of the comparative example. Referring to FIG. 1, the variation of the concrete/mortar strength ratio in the example was smaller than that of the comparative example. From this, even when the clinker composition, the amount of gypsum, the amount of limestone, and the degree of powder are changed, it can be said that there is a correlation between the lattice volume of calcite and σc/σm. That is, if limestone having a lattice volume of 366.76Å ³ or more and 368.00Å ³ or less is used, high concrete strength can be obtained even with the same degree of mortar strength. In addition, the accuracy of the concrete strength estimated from the evaluation by mortar can be improved. In addition, in Examples 1 to 18, the particle ratio of 11 μm or more and less than 22 μm is 18.0 to 26.0%, and the particle ratio of 22 μm or more and less than 44 μm is 31.8 to It was 38.0%. From these results, in Examples 1 to 18, it was considered that the appropriate distribution of particles in the cement composition was one of the factors that improved the concrete/mortar strength ratio.

Claims (5)

Including clinker, gypsum, and limestone,
The volume of the lattice sites of a Calibrator the limestone, 366.76Å ³ or more than ³ 368.00Å cement composition. The method of claim 1,
The clinker,
_{The ratio of 3CaO·SiO 2} calculated by the Vogue equation is 50 to 75% by mass,
_{The ratio of 2CaO·SiO 2} calculated by the Vogue equation is 8 to 30% by mass,
A cement composition in which the ratio of the sum of _{3CaO·Al 2} O ₃ and 4CaO·Al ₂ O _3· Fe ₂ O ₃ calculated by Vogue's formula is 15 to 25% by mass. The method according to claim 1 or 2,
A cement composition in which the particle size distribution by the microtrack method is 18.0% or more and 26.0% or less, and the proportion of particles of 22 μm or more and less than 44 μm is 31.8% or more and 38.0% or less. The method according to claim 1 or 2,
A cement composition having a specific surface area of 3200cm ² /g or more and 3800cm ² /g or less. A method for producing a cement composition comprising the step of pulverizing and mixing limestone having a lattice volume of 366.76Å ³ or more and 368.00Å ^{3 or less of clinker, gypsum, and calsite.}

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