JP7000714B2 - Cement composition and its manufacturing method, and mortar or concrete manufacturing method - Google Patents

Description

The present invention relates to a cement composition containing slag and a method for producing the same. The present invention also relates to a method for producing mortar or concrete.

Blast furnace cement is a cement containing blast furnace slag as a mixed material. In recent years, there has been increasing interest in carbon dioxide emissions during cement manufacturing, and its use is being promoted. On the other hand, blast furnace cement utilizes the latent hydraulic slag of slag, which gradually hardens using calcium hydroxide generated by the hydration reaction of cement as a stimulant, so that setting is delayed compared to ordinary Portland cement. It has been a conventional problem that it takes a long time to harden and obtain sufficient strength.

Previous reports on improving the initial strength and setting delay of blast furnace cement include the addition of calcium hydroxide and gypsum (Patent Document 1), the addition of alkali sulfate (Patent Document 2), and increase the powderiness of gypsum and blast furnace slag (Patent Document 1). Techniques such as Patent Document 3) have been proposed.

Japanese Unexamined Patent Publication No. 2016-155701 Japanese Unexamined Patent Publication No. 2016-190771 Japanese Unexamined Patent Publication No. 2008-179504

However, there is a problem that the production cost increases due to the procurement of additives such as calcium hydroxide and alkali sulfate, and the increase in the powderiness of gypsum and blast furnace slag. Further, when the content of the blast furnace slag exceeds 60% by mass, or when an admixture having a specific component is used, the delay in condensation is remarkable, and further measures are required.

As a result of diligent studies on the above-mentioned problems, the present inventors have found that it is possible to provide a cement composition in which an abnormal setting delay is suppressed by adjusting the amount of _C3A contained in the cement in the cement composition. , The present invention has been completed.

That is, the present invention is a cement composition containing cement and blast furnace slag.
The C ₃ A (in the formula, C represents CaO and A represents Al ₂ O ₃ ) content in the cement is more than 9% by mass and 20% by mass or less.
Provided is a cement composition having a blast furnace slag content of more than 30% by mass and 95% by mass or less.

The present invention also provides a cement composition containing the cement composition, water, and an admixture, wherein the admixture is a polycarboxylic acid-based water reducing agent. Further, the polycarboxylic acid-based water reducing agent provides a cement composition containing gluconic acid.

Further, the present invention is a suitable method for producing the above-mentioned cement composition.
The manufacturing process of the cement composition
A compounding process in which the C ₃ A content and C ₄ AF content calculated by the Borg formula are adjusted by the amount of limestone, silica stone, clay-based raw material, and iron raw material used.
At the rotary kiln f. A firing step of firing clinker so that the CaO content is 0.5 to 3.0% by mass.
It has a crushing step of crushing the clinker, gypsum, and blast furnace slag.
The present invention provides a method for producing a cement composition, which comprises adjusting the _C3A content of the clinker after firing so as to be more than 9% by mass and 20% by mass or less.

Further, the present invention is made by adjusting the _C3A content in the cement composition, the alkali sulfate, the free lime content _, and the _Al2O3 content in the blast furnace slag.
It provides a method for producing mortar or concrete, which suppresses a delay in hardening of a cement composition containing blast furnace slag, water, and an admixture.

According to the present invention, by adjusting the _C3A content and the alkali sulfate content in the cement, it is possible to provide a cement composition in which the delay in condensation is suppressed while suppressing the increase in production cost.

FIG. 1 is a graph showing a method for confirming the presence or absence of gluconate salt in an admixture by NMR. FIG. 2 is a graph showing the relationship between the heat generation rate and time measured for Example 2. FIG. 3 is a graph showing the relationship between the heat generation rate and time measured for Examples 5 and 7.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The cement composition of the present invention comprises cement and blast furnace slag.

The cement in the present invention has a C ₃ A (in the formula, C represents CaO and A represents Al ₂ O ₃ ) content of more than 9% by mass and 20% by mass or less, preferably 13% by mass or more and 18%. It is 1% by mass or less, more preferably 15% by mass or more and 17% by mass or less. By setting the _C3A content in such a range, good coagulation properties can be obtained. Furthermore, since cement with a high _C3A content can use a large amount of raw material waste during manufacturing, it can contribute to reducing the environmental load and improve the coagulation properties without incurring extra costs. It will be possible.

C ₃ A means an aluminate phase, and its chemical formula is 3CaO · Al _{2O 3} . The _C3A content in cement can be determined by the following Borg equation, or by Rietveld analysis of the X-ray diffraction (XRD) pattern of cement. As for the Al ₂ O ₃ content and the Fe ₂ O ₃ content in the cement, the results measured by the method specified in JIS R5202 can be used.
C ₃ A content (% by mass) = 2.65 x (Al ₂ O ₃ content in cement (% by mass)) -1.69 x (Fe ₂ O ₃ content in cement (% by mass))

The cement in the present invention is not particularly limited, but for example, Portland cement specified in JIS R 5210 can be used. The method for producing cement is also not particularly limited, and includes a blending step, a firing step, and a crushing step, and the crushing step can be produced by adding gypsum to, for example, a cement clinker and crushing it with a ball mill. The method for producing cement clinker used for cement is not particularly limited, and the firing step can be one produced by a normal cement firing facility. For example, it is a cement manufacturing facility such as an SP method (multi-stage cyclone preheating method) or an NSP method (multi-stage cyclone preheating method equipped with a calcining furnace).

In particular, cement may contain high C ₃ A clinker with a C ₃ A content of more than 9% by weight, Portland clinker with a C ₃ A content of ₉ % by weight or less, and gypsum. It is preferable because the A content can be easily adjusted. From the viewpoint of further enhancing this advantage, the _C3A content of the high _C3A clinker is preferably more than 9% by mass and 20% by mass or less, more preferably 11% by mass or more and 18% by mass or less, and 12% by mass. % Or more and 16% by mass or less are particularly preferable, and 13% by mass or more and 15% by mass or less are most preferable. On the other hand, the _C3A content of Portland clinker is more preferably 9% by mass or less, and particularly preferably 1% by mass or more and 9% by mass or less. The mass ratio of high _C3A clinker to Portland clinker is preferably 2: 8 to 8: 2, and more preferably 3: 7 to 7: 3.

The raw material of cement clinker (hereinafter, also referred to as clinker) is not particularly limited, and is used for producing cement clinker such as limestone, blast furnace slag, coal ash, sewage sludge, soil generated from construction, silica stone, copper shavings, and clay. You can use the one that is normally used.

The cement content in the cement composition of the present invention is preferably 5% by mass or more and less than 70% by mass, more preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less. It is particularly preferably 20% by mass or more and 40% by mass or less, and most preferably 20% by mass or more and 30% by mass or less. When the cement content is in such a range, good cohesive properties can be maintained while maintaining strength development.

The cement composition of the present invention contains, for example, blast furnace slag such as blast furnace granulated slag and blast furnace slow cooling slag. In order to obtain good coagulation properties, it is preferable to use the blast furnace slag specified in JIS A 6206 “Blast furnace slag fine powder for concrete”. Further, according to the present invention, even when a blast furnace slag that does not conform to the JIS A 6206 standard is used, the coagulation property can be improved, and a blast furnace slag that does not conform to JIS, which was difficult to use in the past, can be effectively used. .. It is preferable that the Al ₂ O ₃ content of the blast furnace slag is 11% by mass or more and 18% by mass or less from the viewpoint of increasing the calorific value at the time of curing and suppressing the curing delay caused by the increase. From the viewpoint of further enhancing this advantage, the Al ₂ O ₃ content of the blast furnace slag is more preferably 11% by mass or more and 16% by mass or less, and more preferably 12% by mass or more and 15% by mass or less. More preferred. Most preferably, it is 14% by mass or more and 15% by mass or less. The Al ₂ O ₃ content of the blast furnace slag is measured by the method described in JIS R 5202. As will be described later, for the blast furnace slag, the blast furnace slag having an Al ₂ O ₃ content of 11% by mass or more and the blast furnace slag having an Al ₂ O ₃ content of less than 11% by mass are sorted and stored separately. In addition, either one may be used at the time of use, or both may be mixed and used after adjusting to an appropriate Al ₂ O ₃ content.

The content of the blast furnace slag in the cement composition of the present invention is more than 30% by mass and 95% by mass or less, preferably 40% by mass or more and 90% by mass or less, and more preferably 50% by mass or more and 90% by mass or less, particularly. It is preferably 60% by mass or more and 80% by mass or less. By setting the blast furnace slag content in such a range, the amount of carbon dioxide generated can be sufficiently reduced and the effect of sufficiently improving the condensation delay can be obtained.

The cement composition of the present invention has a SO ₃ content of preferably 0.01% by mass or more and 5% by mass, more preferably 0.1% by mass or more and 5% by mass or less, and further preferably 1% by mass or more 3 It is 1% by mass or less, and more preferably 1.5% by mass or more and 2.5% by mass or less. By setting the _SO3 content in the cement composition of the present invention in such a range, the condensation delay can be further improved. The SO ₃ content can be adjusted by adjusting the SO ₃ content in the clinker and the amount of gypsum added. The type and manufacturing method of the gypsum to be added are not particularly limited, and dihydrate gypsum, semi-hydrated gypsum, anhydrous gypsum and the like can be used. The SO ₃ content in the cement composition is measured by the method described in JIS R 5202 or JIS R 5204.

The cement composition of the present invention may contain 0.01 parts by mass or more and 1 part by mass or less of alkali sulfate with respect to 100 parts by mass of the total of cement and blast furnace slag. By setting it in such a range, the delay of condensation can be further suppressed. The alkali sulfate content can be adjusted by adding an alkali metal sulfate of sulfuric acid such as sodium sulfate or potassium sulfate as an additive in addition to the alkali sulfate present in the cement cleanser. The amount of alkali sulfate in the clinker can be adjusted by adjusting the _SO3 content and the amount of alkali metal in various steps of the [method for producing a cement composition] described later. The SO ₃ content in the clinker is 0.5% by mass or more and 3.0% by mass, preferably 0.8% by mass or less and 2.5% by mass or less, and more preferably 1.2% by mass or more and 2.0% by mass. Hereinafter, it is most preferably 1.5% by mass or more and 2.0% by mass or less. The amount of alkali metal ₍ R2O) in the clinker is 0.2% by mass or more and 0.8% by mass or less, preferably 0.3% by mass or more and 0.65% by mass or less, and more preferably 0.4% by mass. % Or more and 0.6% by mass or less, most preferably 0.5% by mass or more and 0.55% by mass or less.

The cement used in the cement composition of the present invention is a free lime (hereinafter, also referred to as f.CaO) measured based on the standard test method of the Japan Cement Association (JCAS I-01: 1997 "Method for quantifying free calcium oxide"). The content is 0.5% by mass or more and 3.0% by mass or less, preferably 0.6% by mass or more and 2.0% by mass or less, and more preferably 0.7% by mass or more and 1.5% by mass. % Or less, more preferably 1.0% by mass or more and 1.2% by mass or less. By setting it in such a range, the delay of condensation can be further suppressed. The free lime content can be adjusted by adding calcium hydroxide or the like as an additive in addition to the free lime present in the cement clinker.

The cement composition of the present invention may further contain fly ash specified in JIS A 6201, a siliceous mixture specified in JIS R 5212, a small amount of mixed components specified in JIS R 5210, and the like.

The cement composition of the present invention may also contain gypsum. The type and manufacturing method of gypsum are not particularly limited, and for example, the above-mentioned dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum can be used. Further, the manufacturing method is not particularly limited.

The cement composition of the present invention may further contain a sulfate in addition to or in place of the alkali sulfate as the additive. Examples of the sulfate include lithium sulfate, magnesium sulfate, calcium sulfate and the like in addition to the above-mentioned sodium sulfate and potassium sulfate. These sulfates can be used alone or in combination of multiple sulfates. From the viewpoint of further suppressing the delay of the hydration reaction, it is preferable to use magnesium sulfate when the sulfate is used alone.

When a plurality of sulfates are used in combination, the combination of sulfates is not particularly limited, and examples thereof include a combination of calcium sulfate and magnesium sulfate, a combination of potassium sulfate and calcium sulfate, and the like. The production method and origin of these sulfates are not particularly limited, and for example, each sulfate can be mixed at a predetermined ratio for industrial production, and a natural mineral containing a plurality of sulfates can be used as it is or crushed. It can also be used through the above steps. As the natural mineral, for example, a mineral such as K ₂ SO 4.2 CaSO _{4 (} calcium langbeinite) can be used.

By containing the sulfate, the cement composition of the present invention can suppress the curing delay while reducing the amount of alkali in the cement composition, as compared with the case where the curing delay is controlled by the above-mentioned alkali sulfate alone. Will be.

The amount of sulfate added is not particularly limited, but is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 1 part by mass with respect to 100 parts by mass of the total of cement and blast furnace slag. By including the sulfate in this range, the delay of the hydration reaction can be suppressed.

[Manufacturing method of cement composition]
The method for producing a cement composition of the present invention can include various steps such as a blending step, a firing step, a mixing step, and a crushing step.

In the compounding process, the amount of limestone, silica stone, clay-based raw material, and iron raw material used in order to keep the C ₄ AF content in the cement and the C ₃ A content calculated by the above-mentioned Borg formula within the preferable range of the present invention. The C ₄ AF content and / or the C ₃ A content can be adjusted by increasing or decreasing. In particular, in the compounding step, it is preferable to adjust the _C3A content of the cement clinker after the firing step, which will be described later, so as to be more than 9% by mass and 20% by mass or less from the viewpoint of improving the condensation delay.

In the firing step, by using a rotary kiln such as a rotary kiln, f. It is preferable to bake the cement clinker so that the CaO content is 0.5 to 3.0% by mass in order to obtain the effect of the present invention. Depending on the firing temperature, firing time, etc. f. The CaO content can be adjusted. In addition, even after firing, by adding an additive such as calcium hydroxide in the mixing step and the crushing step described later, f. The CaO content can be adjusted.

In the mixing step and the crushing step, the method of mixing and / or crushing cement clinker, blast furnace slag, gypsum, and a small amount of mixture is not particularly limited. For example, cement clinker, gypsum, and blast furnace slag are mixed and crushed. Examples thereof include a method in which a mixing step and a crushing step are performed at the same time, a method in which a cement cleaner and gypsum are mixed and crushed, and then a separately crushed blast furnace slag is mixed.
The cement clinker is preferably used by mixing and pulverizing a high C ₃ A clinker having a C ₃ A content of more than 9% by mass and a Portland clinker. This makes it easier to adjust the _C3A content in the various steps described above. The _C3A content of the high _C3A clinker is preferably 10% by mass or more and 20% by mass or less, more preferably 11% by mass or more and 18% by mass or less, particularly preferably 12% by mass or more and 16% by mass or less, and 13% by mass. % Or more and 15% by mass or less are most preferable. The _C3A content of Portland clinker is preferably 9% by mass or less, more preferably 1% by mass or more and 9% by mass or less. The mass ratio of high _C3A clinker to Portland clinker is preferably 2: 8 to 8: 2, and more preferably 3: 7 to 7: 3.

In addition, in order to easily adjust the C ₃ A content in the cement composition by mixing the clinker with different C ₃ A content, the high C ₃ A clinker and the Portland clinker should be stored separately. It is preferable to have a raw material receiving process.
Further, from the viewpoint of reducing the influence of quality fluctuation of the blast furnace slag, the blast furnace slag having an Al ₂ O ₃ content of 11% by mass or more and the blast furnace slag having an Al ₂ O ₃ content of less than 11% by mass are selected. It is preferable to have a raw material receiving process for storing the raw materials separately. By having this step, the blast furnace slag having an Al ₂ O ₃ content of 11 to 18% by mass can be selected and used in the pulverization step, and the cement composition of the present invention can be easily obtained.
These raw material receiving steps may be performed at any stage before the crushing step of crushing the cement clinker, gypsum, and blast furnace slag.

When alkali sulfate is contained in the cement composition, in the above-mentioned pulverization step, a clinker containing alkali sulfate and / or an aqueous solution containing alkali sulfate is mixed, and 0.01 part by mass or more with respect to 100 parts by mass of the cement composition. It can be adjusted to be 1 part by mass or less. Further, in the above-mentioned compounding step and / or firing step, the amount of alkali sulfate can also be adjusted by adjusting the _SO3 content and the amount of alkali metal in the clinker.

The cement composition of the present invention preferably has a brain specific surface area of 3000 cm ² / g or more and 4500 cm ² / g or less, more preferably 3300 cm ² / g or more and 4000 cm ² / g or less, and more preferably 3500 cm ² / G or more and 3800 cm ² / g or less. By setting the brain specific surface area in such a range, it is possible to improve the condensation delay while reducing the slump loss. The brain specific surface area is measured using a brain air permeation device, for example, according to JIS R 5201: 1997 "Physical test method for cement".

The cement composition of the present invention may be a cement composition having fluidity such as cement paste, mortar, or concrete by adding water and / or an admixture to the cement composition. The type of the admixture is not particularly limited, and examples thereof include an AE agent, a water reducing agent, an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, and a fluidizing agent. A preferred admixture is a polycarboxylic acid-based water reducing agent. Further, when the admixture contains gluconate, the effect of the present invention becomes remarkable. Although the detailed mechanism is not clear, in general, when an admixture containing gluconate is applied to blast furnace cement, a significant delay in condensation occurs. However, according to the cement composition of the present invention, gluconate is contained in the admixture. Even if the acid salt is contained, the delay in coagulation can be effectively improved. In particular, by adjusting the _C3A content in the cement composition, the alkali sulfate, the free lime content _, and the _Al2O3 content in the blast furnace slag within the above range, the setting delay is suppressed. The desired mortar or concrete can be produced.

The structure of the admixture can be known by various structural analyzes such as ¹ H-NMR and FT-IR. In particular, regarding the presence / absence and content of gluconate in the admixture, the presence / absence and integrated value of peaks containing low molecular weight components such as gluconate appearing in the chemical shift of 3.75 to 4.75 ppm of ¹ H-NMR spectrum. It can be calculated from. From the viewpoint of more accurately measuring the presence / absence and content of gluconate in the admixture, it is particularly quantified using peaks around 4.15 ppm and 4.05 ppm, which have relatively little overlap with coexisting components. preferable.

The amount of the admixture used is not particularly limited, and if the amount of the admixture is generally used, the condensation delay can be improved. For example, the amount of the admixture used is 0.01 parts by mass or more and 5 parts by mass or less, more preferably 0.5 parts by mass or more and 3 parts by mass or less, still more preferably, with respect to 100 parts by mass of the cement composition. It is 1 part by mass or more and 2 parts by mass or less. Within such a range, the condensation delay can be suppressed more effectively.

The method for suppressing the curing delay of the present invention comprises the amount of _C3A in the cement composition, f. By adjusting the amount of CaO _, the amount of alkali sulfate, and the amount of _Al2O3 in the blast furnace slag, the delay in condensation of cement paste, mortar, and concrete is suppressed. If the admixture used is a polycarboxylic acid-based water reducing agent, the effect of delaying condensation can be further exhibited. If gluconate is contained in the water reducing agent, the effect can be further exerted.

Hereinafter, the contents of the present invention will be described in detail with reference to Examples, Comparative Examples and Reference Examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%".

[1. Cement manufacturing]
Industrial reagents such as calcium carbonate, silicon dioxide, iron (IV) oxide, aluminum oxide, magnesium carbonate, sodium carbonate, potassium carbonate, and dihydrate gypsum were mixed as raw materials and fired at 1450 ° C. to obtain a cement clinica. The results of measuring the chemical composition of the obtained cement clinker based on JIS R 5202: 2015 "Chemical analysis method of cement" and the Borg mineral composition calculated from the chemical composition of cement clinker are shown in Table 1 as clinker 1 and clinker 2. ..
The obtained cement clinker or a mixture of cement clinker is mixed with dihydrate gypsum so that the SO ₃ content in the cement composition is 1.8 ± 0.1% by mass, and the brain specific surface area is 3300 ± 50 cm ² . Cement 1 to 3 shown in Table 2 was produced by pulverizing with a ball mill so as to have a value of / g. Table 2 shows the results of composition analysis using fluorescent X-rays (XRF) for these cements, and the free lime content measured by JCAS I-01: 1997 “Method for quantifying free calcium oxide”. In Tables 1 and 2, C represents CaO, S represents SiO ₂ , A represents Al ₂ O ₃ , and F represents Fe ₂ O ₃ . f. CaO stands for free lime.

[2. Manufacture of cement composition]
To the produced cement, blast furnace slag, potassium sulfate, calcium hydroxide, magnesium sulfate, and calcium sulfate were added as shown in Table 4 below to obtain cement compositions of Examples, Comparative Examples, and Reference Examples. In some cements, the amount of free lime in the cement was adjusted by adding calcium hydroxide. In addition, the amount of alkali sulfate in the cement composition was adjusted by adding potassium sulfate. In Example 11, as an experiment simulating the addition of calcium langbeinite ₍ K ₂ SO 4.2 CaSO ₄ ), potassium sulfate and calcium sulfate were added and mixed at a molar ratio of 1: 2 to produce a cement composition. did. Table 3 below shows the physical properties of the blast furnace slag used as slags 1 to 3. _In some blast furnace slags, dihydrate gypsum was added to adjust the SO3 content. Nisui gypsum, calcium hydroxide, potassium sulfate, magnesium sulfate, and calcium sulfate used the special grade reagents of Wako Pure Chemical Industries, Ltd.
Further, in Reference Examples 1 and 2, commercially available ordinary Portland cement (OPC) was used instead of cement clinker and gypsum, and the curing delay effects of the admixtures A and B were compared. As shown in Table 5, the admixtures A and B are both polycarboxylic acid-based water reducing agents, but A does not contain gluconate and B contains gluconate.

[3. Evaluation of condensation time]
Water and the admixture shown in Table 5 so that the water powder mass ratio (water / cement composition) = 0.5 with respect to the prepared cement composition (0.5 to 0.5 by external division with respect to the cement composition) A mixed solution of 1.0% by mass) was added and kneaded to obtain a cement paste. The amount of admixture was a part of the amount of water. The structure of the admixture was measured using ¹ H-NMR, and when a peak with a chemical shift of 3.75 to 4.75 ppm was present, it was determined that a low molecular weight component such as gluconate was contained. FIG. 1 shows an example of the judgment result.
The measurement conditions for ¹ H-NMR are shown below.
Measuring device: Bruker Biospin, AVANCE 500 type Measuring solvent: ¹ H
Measurement temperature: 27 ° C
Solvent: heavy water

Regarding the admixture B containing gluconate, the gluconate content was analyzed by the absolute quantification method using ¹ H-NMR. Sodium gluconate in which a predetermined amount was dissolved in heavy water was measured by ¹ H-NMR, and a calibration curve was prepared from the relationship between the integrated value of the peaks of 4.15 ppm and 4.05 ppm and the sample amount. From the peak integral value of sodium gluconate in the admixture B measured by the same method, the amount of sodium gluconate in the admixture B was 3.7% by mass as a result of applying it to the prepared calibration curve and quantifying it.

The obtained cement composition was immediately measured for hydration heat generation rate using a cement hydration calorimeter (CHC-OM6, manufactured by Tokyo Riko Co., Ltd.), and the time required for the start of condensation was investigated. Specifically, focusing on the second hydration exothermic peak caused by the hydration reaction of the blast furnace slag, the linear approximation curve of the exothermic rate plot at the rising part of the second peak and the linear approximation curve of the exothermic rate plot in the induction period. The intersection with and was taken as the condensation start time. FIG. 2 shows a graph of the relationship between the heat generation rate and time measured for Example 2.

[4. result〕
The results are shown in Table 4. When comparing the curing retarding effects of the admixtures A and B at the same addition amount in Reference Examples 1 and 2, the admixture B containing 3.7% by mass of gluconic acid is more than the admixture A containing no gluconic acid. It can be seen that the effect of delaying condensation is high. Further, in the cement composition of each example, the curing delay was suppressed by setting the _C3A content of the cement clinker to more than 9% by mass. In particular, the effect was remarkable when the admixture B having a large condensation delay effect was used.
In addition, the effect was higher than that of the conventional technique in which the alkali sulfate content, the free lime content, and the SO ₃ content were adjusted. The delay in condensation was further suppressed by increasing the _C3A content to more than 9% by mass and further increasing the alkali sulfate content, the free lime content and the SO3 content (Examples ₃ , 4, 6 and 8). .. In Examples 7 and 10, the accumulated heat generation is compared with Examples 5 and 9 in which the Al ₂ O ₃ content of the slag is 11 to 14% by mass and the Al ₂ O ₃ content of the slag is 15% by mass, respectively. The amount increased (Fig. 3). Further, in Examples 11 and 12 containing sulfate, although the _C3A content of the cement was lower than that in Examples 1 and 2, the delay in condensation was suppressed to the same extent. I understand. As described above, according to the cement composition of the present invention, the delay in curing is suppressed and hydration is promoted.

Claims (16)

A cement composition containing a powder containing cement and blast furnace slag, and water and an admixture.
The C ₃ A (in the formula, C represents CaO and A represents Al ₂ O ₃ ) content in the cement is 10% by mass or more and 20% by mass or less.
The content of the cement in the powder is 5% by mass or more and 60% by mass or less.
The content of the blast furnace slag in the powder is 40% by mass or more and 95% by mass or less.
A cement composition containing the admixture in an amount of 0.5 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the powder . The cement according to claim 1, wherein the cement comprises a high C ₃ A clinker having a C ₃ A content of more than 9% by mass, a Portland clinker having a C ₃ A content of 9% by mass or less, and gypsum. Cement composition. The content of the cement in the powder is 10% by mass or more and 50% by mass or less.
The cement composition according to claim 1 or 2, wherein the content of the blast furnace slag in the powder is 50% by mass or more and 90% by mass or less. The cement composition according to any one of claims 1 to 3, wherein the Al ₂ O ₃ content of the blast furnace slag is 11% by mass or more and 18% by mass or less. The cement composition according to any one of claims 1 to 4, wherein the free lime content in the cement is 0.5% by mass or more and 3.0% by mass or less. The cement composition according to any one of claims 1 to 5, wherein the SO ₃ content is 0.01% by mass or more and 5% by mass or less. The cement composition according to any one of claims 1 to 6, which contains 0.01 part by mass or more and 1 part by mass or less of alkali sulfate with respect to 100 parts by mass in total of the cement and the blast furnace slag. The cement comprises high _C3A clinker with a _C3A content greater than 9% by weight, Portland clinker with a _C3A content of 9% by weight or less, and gypsum.
The cement composition according to any one of claims 1 to 7, wherein the mass ratio of high C3 A clinker to Portland clinker is ₂ : 8 to 8: 2. The admixture is a polycarboxylic acid-based water reducing agent.
The cement composition according to claim 8, wherein the polycarboxylic acid-based water reducing agent contains a gluconate salt. The cement composition according to any one of claims 1 to 9, further comprising a sulfate. The method for producing a cement composition according to any one of claims 1 to 10.
The manufacturing process of the cement composition
A compounding process in which the C ₃ A content and C ₄ AF content calculated by the Borg formula are adjusted by the amount of limestone, silica stone, clay-based raw material, and iron raw material used.
At the rotary kiln f. A firing step of firing clinker so that the CaO content is 0.5 to 3.0% by mass.
It has a crushing step of crushing the clinker, gypsum, and blast furnace slag.
A method for producing a cement composition, wherein the compounding step is adjusted so that the _C3A content of the clinker after firing is adjusted to be more than 9% by mass and 20% by mass or less. Includes a raw material receiving step in which blast furnace slag having an Al ₂ O ₃ content of 11% by mass or more and blast furnace slag having an Al ₂ O ₃ content of less than 11% by mass are sorted and stored separately.
The method for producing a cement composition according to claim 11, wherein in the pulverization step, blast furnace slag having an Al ₂ O ₃ content of 11 to 18% by mass is selected and used. The compounding step is characterized in that the _C3A content of the clinker after firing is adjusted to be more than 9% by mass and 20% by mass or less.
In the firing step, the high C ₃ A clinker having a C ₃ A content of more than 9% by mass and 20% by mass or less and the Portland clinker having a C ₃ A content of 9% by mass or less were separately stored.
The method for producing a cement composition according to claim 11 or 12, wherein in the crushing step, the high _C3A clinker and the Portland clinker are mixed and pulverized. In the compounding step and / or the firing step,
The SO3 content and the alkali metal content in the clinker _are adjusted so that the amount of alkali sulfate in the cement composition is 0.01 part by mass or more and 1 part by mass or less with respect to 100 parts by mass of the cement composition. The method for producing a cement composition according to any one of claims 11 to 13. In the crushing step,
A clinker containing alkali sulfate and / or an aqueous solution containing alkali sulfate is used so that the amount of alkali sulfate in the cement composition is 0.01 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the cement composition. The method for producing a cement composition according to any one of claims 11 to 14, wherein the cement composition is mixed. Mortar or concrete using the cement composition according to any one of claims 1 to 10 or using the cement composition obtained by the production method according to any one of claims 11 to 15. A method of manufacturing mortar or concrete.

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