WO2014097938A1

WO2014097938A1 - Cement and blended cement

Info

Publication number: WO2014097938A1
Application number: PCT/JP2013/083158
Authority: WO
Inventors: 修久保田; 大亮黒川; 宙平尾; 秀幸菅谷
Original assignee: 太平洋セメント株式会社
Priority date: 2012-12-18
Filing date: 2013-12-11
Publication date: 2014-06-26
Also published as: TW201437177A

Abstract

Provided are: a cement which enables the increase in the use amount of a waste material that can be used as a raw material for a burned material (clinker) and which has the same physical properties as those of high-early-strength portland cement; and a blended cement containing the cement. A cement which comprises a pulverized product of a burned material having a hydraulic modulus (H.M.) of 2.10 to 2.30, a silica modulus (S.M.) of 1.80 to 2.48, an iron modulus (I.M.) of 1.3 to 2.6, and a 3CaO·SiO₂ content of 70.0 mass% or less in 100 mass% of the burned material as calculated in accordance with the Bogue formula and gypsum, wherein the content ratio of the gypsum in 100 mass% of the cement is 1.2 mass% or more in terms of SO₃ content, and the amount of gypsum hemihydrate relative to the total amount of gypsum dihydrate and the gypsum hemihydrate in the cement is 30 mass% or more in terms of SO₃ content; and a blended cement which comprises the cement and a cement admixture material, wherein the cement admixture material comprises a blast furnace slag fine powder and/or coal ash.

Description

Cement and mixed cement

This invention relates to the cement which can increase the usage-amount of the waste used as a raw material of a baked material (clinker), and the mixed cement containing this cement.

In Japan, industrial waste and general waste are rapidly increasing with economic growth and population concentration in urban areas. Conventionally, most of these wastes have been landfilled after being reduced to a sufficient volume by incineration, but recently, the remaining capacity of landfill sites has become tight, so new waste Establishing treatment methods is an urgent issue. In order to cope with this problem, in the cement industry, industrial waste, general waste, and the like are used as raw materials for cement and energy for firing clinker.
For example, Patent Document 1 discloses that in the production of a cement clinker using 150 to 350 kg of coal ash per ton of clinker as a raw material, the hydraulic modulus (HM) is 1.8 to 2.3, silicic acid. A cement raw material containing coal ash was blended so that the rate (SM) was 1.3 to 2.3 and the iron rate (IM) was 1.8 to 2.8. Gypsum is mixed with a cement clinker so that the total SO ₃ amount is 2.0 to 10.0% and pulverized or separated and pulverized from each other and mixed to obtain a Blaine specific surface area of 3,000 to 4,500 cm ^2. A method for producing a cement composition of / g is described.

However, in recent years, the amount of waste used, especially the amount of raw material alternative waste (for example, coal ash), has reached its peak. Therefore, as one of the measures for further increasing the amount of waste used, it is possible to expand the use of waste to cement varieties other than ordinary cement. Here, since most of the raw material substitute waste is clay substitute waste rich in Al ₂ O _3, when the amount of waste increases, the cement clinker interstitial phase (aluminate phase: 3CaO · Al ₂ O ₃ , also referred to as "C ₃ a"), and the ferrite _{phase:.. 4CaO · Al 2 O} 3 · Fe 2 O 3 ( hereinafter also referred to as "C ₄ AF")) increases, the cement hydration heat as a result of There is a problem of increasing. However, early strength Portland cement is hardly used for the production of large structures where the heat of hydration of cement is a major problem, and is therefore suitable as a variety that can increase the amount of waste used.
For example, Patent Document 2 discloses a base material for early-strength cement-based solidified material and early-strength cement, and the proportion of mineral composition in the Borg formula is 3CaO · SiO ₂ (also referred to as “Alite” (hereinafter “C ₃ S”). .))> 70% highly active cement clinker, and when the hydraulic modulus (HM) of the highly active cement clinker is 2.2 to 2.3, the silicic acid ratio (SM) ) Is 1.7 to 2.4, the iron ratio (IM) is 1.0 to 2.1, and the hydraulic modulus (HM) is less than 2.1 to 2.2 A highly active cement clinker having a silicic acid ratio (SM) of 1.5 to 2.0 and an iron ratio (IM) of 0.9 to 1.4 is described. Patent Document 2 describes that industrial waste containing 20% by weight or more of calcium in terms of CaO can be used as the main raw material of the highly active cement clinker.

On the other hand, the cement industry emits carbon dioxide equivalent to about 4% of Japan's total greenhouse gas emissions. About 2.4% of carbon dioxide, corresponding to 60% of this about 4%, is inevitably generated from the decarboxylation of limestone when producing cement clinker. For this reason, unless the production volume of cement clinker is reduced, it is difficult to reduce carbon dioxide emissions. The reduction in the production amount of cement clinker not only suppresses the decarboxylation amount of limestone, but also suppresses the generation amount of carbon dioxide derived from fuel in cement clinker firing.

¡Mixed cement uses a large amount of blast furnace slag fine powder, fly ash, etc., so the amount of clinker added can be greatly reduced. Therefore, the “Kyoto Protocol Target Achievement Plan” states that the proportion of mixed cement production in Japan's cement production in 2010 will be 24.8% from the viewpoint of reducing carbon dioxide emissions in the cement industry. Has set goals. However, since mixed cement has problems such as poor initial strength, its production has been flat for about 21% of the total cement production in recent years.

Then, the trial which solves the problem of the mixed cement mentioned above is performed by making the early-strength-type cement which has initial strength expressibility into the base material of a mixed cement.
For example, Patent Document 3 discloses that the mineral composition calculated by the Borg formula has C ₃ S> 70% and C ₂ S <5%. S. D. Is obtained by adding gypsum to 1.5 to 4.0% by weight in terms of SO ₃ to a highly active cement clinker having a free lime content of more than 1 and 0.5 to 7.5% by weight. A neutralization-suppressing type early-strength cement composition characterized by comprising 3% to 40% by weight of an inorganic admixture composed of at least one of blast furnace slag, anhydrous gypsum, fine limestone powder, and pozzolanic material is described. Has been.

In addition, blast furnace slag fine powder, coal ash (for example, fly ash), etc. used for the cement mixed material constituting the mixed cement, those that satisfy the JIS standard are used from the viewpoint of ensuring the quality of the mixed cement. Yes. Low quality blast furnace slag fine powder is used as a cement clinker raw material even if it is outside the JIS standard or within the JIS standard, but if these can be used as a cement mixture, it will be fired (cement clinker (Heating for obtaining) is unnecessary, which is preferable from the viewpoint of environmental load.

Japanese Patent No. 4157762 JP 2012-197198 A JP 2013-47153 A

Since early-strength Portland cement is required to have excellent initial strength, it is necessary to make the C ₃ S content and hydraulic modulus (HM) higher than a certain value. In this way, if the C ₃ S content and hydraulic modulus (HM) are to be set to a certain value or more, there is a limit (lower limit) on the CaO content in the clinker chemical composition. Therefore, there is a limit to the amount of waste (in particular, clay substitute waste) that has the effect of reducing the CaO content. Moreover, since the early strong Portland cement has a high hydraulic modulus and a large specific surface area, there is a problem that a lot of energy is required for production, such as a longer grinding time, and the production cost is higher than that of ordinary cement.
On the other hand, in the mixed cement, low-quality blast furnace slag fine powder and coal ash (for example, fly ash), which has not been used as a cement mixing material from the viewpoint of the quality of the mixed cement, are mixed with the cement that constitutes the mixed cement. If it can be used as a material, it is preferable from the viewpoint of waste utilization.
Therefore, the present invention can increase the amount of waste used as a raw material of the baked product (clinker), and has physical properties equivalent to those of early-strength Portland cement (specifically, setting properties and strength development). And fluidity) and a mixed cement that is excellent in initial strength development and that can use a low-quality cement mixed material.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that the calcination product of the calcined product having a hydraulic rate, silicic acid rate, iron rate, and C ₃ S content within a specific numerical range The present inventors have found that the above object can be achieved by using a cement containing a specific gypsum at a specific blending ratio, thereby completing the present invention.
That is, the present invention provides the following [1] to [8].
[1] (A) Hydraulic modulus (HM) is 2.10-2.30, Silicic acid ratio (SM) is 1.80-2.48, Iron ratio (IM) Is a pulverized product of a calcined product in which the ratio of 3CaO.SiO ₂ in 100% by mass of the calcined product is 70.0% by mass or less as calculated by the Borg formula, and gypsum In which the proportion of gypsum in 100% by mass of the cement is 1.2% by mass or more in terms of SO ₃ , and half of the total amount of dihydrate gypsum and hemihydrate gypsum in the cement Cement characterized in that the ratio of hydropaste is 30% by mass or more in terms of SO ₃ .
[2] The cement according to [1], wherein the fired product is fired using at least one of waste and generated soil as part of a raw material.
[3] The method for producing a cement according to [1] or [2], wherein at least one of waste of 300 kg or less and generated soil is used as a part of raw material per 1 ton of the fired product. A method for producing cement, which is characterized.
[4] A mixed cement comprising the cement according to [1] or [2] and (B) a cement mixed material including at least one of blast furnace slag fine powder and coal ash.
[5] The mixed cement according to [4], wherein the proportion of the cement mixture in the mixed cement is 5 to 80% by mass.
[6] The mixed cement according to [4] or [5], wherein the 28-day activity index of the cement mixed material is 50% or more.
[7] The mixed cement according to any one of [4] to [6], further including fine limestone powder as the cement mixed material.
[8] The method for producing a mixed cement according to any one of [4] to [7], wherein at least one of waste of 300 kg or less and generated soil per 1 ton of the fired product is used as a part of the raw material. A method for producing a mixed cement, characterized by being used.

The cement of the present invention has physical properties equivalent to those of early-strength Portland cement (specifically, setting properties, strength development, and fluidity).
Moreover, since the cement of this invention can increase the usage-amount of the waste used as a raw material of a baked material (clinker) and generated soil, it can promote the effective utilization of a waste more.
Furthermore, the cement of the present invention and the mixed cement containing blast furnace slag fine powder and coal ash as a cement mixture are excellent in initial strength development. Further, the mixed cement is excellent in strength development even when low quality blast furnace slag fine powder or coal ash is used as a cement mixed material.

The cement of the present invention has a hydraulic modulus (HM) of 2.10 to 2.30, a silicic acid ratio (SM) of 1.80 to 2.48, and an iron ratio (IM). Is 1.3 to 2.6, and the amount of C ₃ S in 100% by mass of the calcined product is 70.0% by mass or less as calculated by the Borg formula, and includes a pulverized product of gypsum The ratio of gypsum in 100% by mass of cement is 1.2% by mass or more in terms of SO ₃ , and hemihydrate gypsum with respect to the total amount of dihydrate gypsum and hemihydrate gypsum in the cement Is a cement having a proportion of 30% by mass or more in terms of SO ₃ .
In addition, each coefficient of the said baked product (clinker) can be adjusted by mixing the raw material mentioned later so that it may become in the said numerical range.

The hydraulic modulus (HM) of the fired product used in the cement of the present invention is 2.10 to 2.30, preferably 2.15 to 2.25, more preferably 2.20 to 2.24. is there. When the hydraulic modulus exceeds 2.30, the content of C ₃ S in the fired product increases, and the short-term strength (within 3 days of age) of the cement becomes excessive. Moreover, the long-term (for example, material age 28 days) intensity | strength expression property of cement worsens. Moreover, the hydration heat value of cement becomes excessive. Furthermore, the easy baking property at the time of manufacturing a baked product worsens, and free lime (CaO) tends to remain in the obtained baked product. When the hydraulic modulus is less than 2.10, the content of C ₃ S in the fired product is reduced, and the short-term strength development of the cement is deteriorated.

The silicic acid ratio (SM) of the fired product is 1.80 to 2.48, preferably 2.00 to 2.47, more preferably 2.20 to 2.46, and particularly preferably 2.30 to 2.45. When the silicic acid ratio exceeds 2.48, it is difficult to perform calcination when producing a baked product, and free lime (CaO) tends to remain in the obtained baked product. In addition, the amount of waste used cannot be increased. When the silicic acid ratio is less than 1.80, the content of C ₃ A and C ₄ AF in the fired product increases, and the strength development of the cement over a long period of time (for example, age 28 days) deteriorates. In addition, the fluidity and workability of mortar, concrete or paste (hereinafter, also referred to as “mortar etc.”) prepared using the fired product are deteriorated. Moreover, since the ratio of gypsum required in order to ensure the quality of cement increases, manufacturing cost becomes high. Moreover, the hydration heat value of cement becomes excessive. Furthermore, the pulverizability of the fired product is deteriorated and the production cost is increased.

The iron ratio (IM) of the fired product is 1.3 to 2.6, preferably 1.6 to 2.5, and more preferably 1.8 to 2.4. When the iron ratio exceeds 2.6, the content of C ₃ A in the fired product increases, and the fluidity and workability of mortar and the like deteriorate. Moreover, since the ratio of gypsum required in order to ensure the quality of cement increases, manufacturing cost becomes high. Furthermore, the hydration heat value of cement becomes excessive. When the iron ratio is less than 1.3, the content of C ₃ AF in the fired product is increased, and the pulverizability of the fired product is deteriorated, resulting in an increase in production cost.

The content of C ₃ S in the fired product is 70.0% by weight or less, preferably 50.0 to 70.0% by weight, more preferably as a ratio in 100% by weight of the fired product. It is 60.0-70.0% by mass. When the proportion of C ₃ S exceeds 70.0% by mass, the setting time of cement is shortened.
In the present _{_{specification, C 3 S, C 2 S}} , C 3 A, each content of C ₄ AF in calcined product, as a percentage of the calcined product in 100% by mass (mass%), raw or baked product Based on the chemical composition of the above, it is calculated using the following Borg formula.
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 (%)

As a raw material of a baked product (clinker), the general raw material used for manufacture of a Portland cement clinker can be used. Specifically, CaO raw materials such as limestone, quicklime and slaked lime; SiO ₂ raw materials such as silica and clay; Al ₂ O ₃ raw materials such as clay; Fe ₂ O ₃ raw materials such as iron cake and iron cake may be used. it can.
Furthermore, in addition to the raw material, at least one of waste and generated soil can be used as a part of the raw material.
In this specification, “waste” refers to industrial waste or general waste.
Industrial waste refers to waste generated from business activities.
Examples of industrial waste include raw consludge, various sludges (eg, sewage sludge, purified water sludge, steelmaking sludge, etc.), building wastes, concrete wastes, various incineration ash (eg, coal ash), foundry sand, rock wool, waste Examples thereof include glass and blast furnace secondary ash.
General waste refers to waste other than industrial waste.
Examples of general waste include sewage sludge dry powder, municipal waste incineration ash, and shells.
Note that “waste” does not include “deposited soil” to be described later.
In this specification, “development soil” means earth and sand generated secondary to construction work (for example, boring waste soil generated by excavation of the ground) and sludge (construction sludge; for example, cement generated by ground improvement work) A mixture of milk and excavated soil.
Of these, coal ash is preferably used from the viewpoint of ease of use.

The amount of waste or generated soil used (the total amount when waste and generated soil are used in combination) is a fired product from the viewpoint of promoting effective use of waste and ensuring the quality of cement. It is preferably 300 kg or less, more preferably 170 to 300 kg, further preferably 180 to 280 kg, further preferably 183 to 280 kg, further preferably 185 to 280 kg, and particularly preferably 190 to 260 kg per ton.

As a method for producing a fired product, the above-described raw materials are mixed so as to have a desired hydraulic modulus (HM), silicic acid rate (SM), and iron rate (IM). The resulting mixture is preferably fired at 1,200 to 1,600 ° C., more preferably 1,350 to 1,500 ° C.
The method of mixing each raw material is not particularly limited, and may be performed by a common apparatus such as an air blending silo. Moreover, the apparatus used for baking is not specifically limited, For example, conventional apparatuses, such as a rotary kiln, can be used. When firing in a rotary kiln, fuel alternative waste, specifically wood waste, waste oil, waste tire, waste plastic, etc. can be used. By using fuel alternative waste, the use of waste can be further promoted.

The cement of the present invention includes the pulverized product of the fired product and gypsum. The proportion of gypsum in 100% by mass of cement is 1.2% by mass or more, preferably 1.3 to 5.0% by mass, more preferably 1.4 to 4.0% by mass in terms of SO ₃ .
When the amount of gypsum is less than 1.2% by mass, the strength development property of cement and the fluidity of mortar and the like deteriorate.
Examples of the gypsum include dihydrate gypsum, α-type or β-type hemihydrate gypsum, and anhydrous gypsum. These can be used alone or in combination of two or more.
The amount of SO ₃ in the cement can be determined by chemical analysis (“JIS R 5202 (chemical analysis method of cement)”) or fluorescent X-ray analysis (“JIS R 5204 (fluorescence X-ray analysis method of cement)”. ). The quantification of dihydrate gypsum and hemihydrate gypsum can be carried out, for example, by the method described in JP-A-6-242035.

The ratio of hemihydrate gypsum to the total amount (100% by mass) of dihydrate gypsum and hemihydrate gypsum in cement is 30% by mass or more, preferably 50% by mass or more, more preferably 70% by mass or more in terms of SO _3. is there. When the ratio is 30% by mass or more, fluidity such as mortar can be improved.
Furthermore, the kind of gypsum depending on the origin is not particularly limited, and for example, natural gypsum, flue gas desulfurization gypsum, phosphate gypsum, titanium gypsum, hydrofluoric gypsum, refined gypsum, and the like can be used. These can be used alone or in combination of two or more.

As the method for producing the cement of the present invention, for example, (i) a method of simultaneously pulverizing a baked product (clinker) and gypsum, (ii) a method of pulverizing a baked product (clinker) and mixing the pulverized product and gypsum, etc. Is mentioned.
In the case of the method (i), the fired product and gypsum are pulverized until the Blaine specific surface area is preferably 3,000 to 6,000 cm ² / g, more preferably 3,500 to 5,500 cm ² / g. .
In the case of the above method (ii), the fired product is pulverized until the Blaine specific surface area is preferably 3,000 to 5,500 cm ² / g, more preferably 3,500 to 5,000 cm ² / g. Further, the specific surface area of glaine of gypsum used in the method (ii) is preferably 3,500 to 7,000 cm ² / g, more preferably 4,000 to 6,500 cm ² / g.
The Blaine specific surface area can be measured by “JIS R 5201 (Cement physical test method)”.

The cement of the present invention is based on “JIS R 5210 (Portland cement)”, and other materials in powder form (specifically, blast furnace slag powder, silica fume, fly ash, limestone powder, etc.) are 100% by mass of cement. It can contain in the ratio of 5 mass% or less as a ratio in.

The mixed cement of the present invention includes the above-mentioned (A) cement and (B) a cement mixed material containing at least one of blast furnace slag fine powder and coal ash.
The proportion of the cement mixed material in 100% by mass of the mixed cement is preferably 5 to 80% by mass, more preferably 30 to 70% by mass, and particularly preferably 40 to 60% by mass. If this ratio is 5 mass% or more, the usage-amount of baking products (clinker) can be reduced more. If this ratio is 80 mass% or less, the strength development property of a cement will improve more.
In addition, in this specification, (A) component (cement containing the pulverized material and gypsum of a baked product), and (A) component and (B) component (cement mixed material; For example, blast furnace slag fine powder, coal ash, The mixed cement containing limestone fine powder or the like is a powdery mixture.

The 28-day activity index of the cement mixture is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more. If the 28-day activity index is 50% or more, the strength development of the mixed cement is further improved.
Here, the 28-day activity index is based on the compressive strength of a mortar produced using ordinary Portland cement at the age of 28 days, and produced using a mixed material and ordinary Portland cement with respect to the compressive strength. The ratio of the compressive strength of the test mortar at the age of 28 days is expressed as a percentage.

As blast furnace slag fine powder used as a cement mixture, molten slag produced as a by-product in the production of pig iron in the blast furnace is quenched with water and granulated slag obtained by crushing, or slowly cooled and crushed. The obtained slow cooling slag is mentioned.
The 28-day activity index of the blast furnace slag fine powder is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more from the viewpoint of promoting the utilization of low-quality blast furnace slag fine powder. If the 28-day activity index is 50% or more, the strength development of the mixed cement is further improved.
Even within the above range, from the viewpoint of strength development, the 28-day activity index of the blast furnace slag fine powder is preferably 75% or more, more preferably 80% or more, and particularly preferably 90% or more.
The 28-day activity index of blast furnace slag fine powder should be determined according to “JIS A 6206 Annex (normative) (Activity index and flow value ratio test method using mortar of blast furnace slag fine powder)”. it can.
The 28-day activity index of “blast furnace slag fine powder 4000” defined in “JIS A 6206” is 75% or more.
The mixed cement of the present invention containing fine blast furnace slag powder is excellent in strength development (particularly, initial strength development). Moreover, even if low quality blast furnace slag fine powder having a low activity index on the 28th is used as the blast furnace slag fine powder, the above mixed cement has a standard value of “JIS R 5211 (blast furnace cement)” for compressive strength. Satisfied.

The vitrification rate of the blast furnace slag fine powder is not particularly limited, but is preferably 2% or more, more preferably 3% or more. When the vitrification rate is 2% or more, the strength development of the mixed cement is further improved.
Here, the said vitrification rate can be calculated | required by the following (i) and (ii), for example.
(I) After screening 62-105 μm blast furnace slag fine powder, 400-500 particles are randomly extracted from the powder.
(Ii) Next, the extracted particles are immersed in a bromonaphthalene solution, the number of glass particles is counted through a polarizing microscope, and the vitrification ratio is determined as the ratio of the number of glass particles to the total number of particles.

The specific surface area of the blast furnace slag fine powder is preferably 3,000 to 10,000 cm ² / g, more preferably 4,000 to 8,000 cm ² / g. If the Blaine specific surface area is 3,000 cm ² / g or more, the initial strength development of the mixed cement is further improved. Moreover, if a Blaine specific surface area is 10,000 cm < ² > / g or less, acquisition will be easy and fluidity | liquidity and workability | operativity, such as a mortar using a mixed cement, will improve more.
The blast furnace slag fine powder can be obtained by pulverizing blast furnace slag with a pulverizer such as a ball mill or a jet mill.
The basicity of the blast furnace slag fine powder is preferably 1.7 or more, more preferably 1.8 or more, and particularly preferably 1.9 or more. When the basicity is 1.7 or more, the strength expression of the mixed cement is further improved. The basicity is calculated using the following formula (1).
Basicity = (CaO + MgO + Al ₂ O ₃ ) / SiO ₂ (1)
(The chemical formula in the formula represents the content (mass%) in the blast furnace slag fine powder.)

Furthermore, the blast furnace slag fine powder may contain gypsum (gypsum-containing blast furnace slag fine powder). Examples of the gypsum contained in the blast furnace slag fine powder include anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, etc., and at least one of these may be contained. The content of gypsum in the blast furnace slag fine powder is preferably 2 to 4% by mass, more preferably 2 to 3% by mass in terms of SO ₃ .

In the present invention, the proportion of fine blast furnace slag powder in 100% by mass of the mixed cement is preferably 30 to 80% by mass, more preferably 35 to 75% by mass.
Even within the above range, the proportion of fine blast furnace slag powder in 100% by mass of the mixed cement is preferably 50% by mass or less, more preferably 45% by mass or less from the viewpoint of strength development.
Further, from the viewpoint of promoting utilization of the blast furnace slag fine powder, the ratio of the blast furnace slag fine powder in 100% by mass of the mixed cement is preferably 50% by mass or more, and more preferably 55% by mass or more.

Examples of the coal ash used as the cement mixed material include fly ash. Fly ash refers to fine powder collected by an electrostatic precipitator among coal ash generated when coal is fired.
The 28-day activity index of coal ash is preferably 50% or more, more preferably 60% or more, and particularly preferably 70% or more, from the viewpoint of promoting utilization of low-quality coal ash. If it is 50% or more, the strength expression of the mixed cement is further improved.
Even within the above range, from the viewpoint of strength development, the 28-day activity index of coal ash is preferably 75% or more, more preferably 80% or more.
The 28-day activity index of coal ash can be determined according to “JIS A 6201 Appendix 2 (normative) (flow value ratio and activity index test method using fly ash mortar)”.
In addition, the 28-day activity index of “fly ash type II” defined in “JIS A 6201” is 80% or more.
The mixed cement of the present invention containing coal ash is excellent in strength development (particularly, initial strength development). Moreover, even if low quality coal ash having a low 28-day activity index is used as the coal ash, the mixed cement satisfies the standard value of “JIS R 5213 (fly ash cement)” for compressive strength.

Moreover, the 45-micrometer sieve residue amount of coal ash becomes like this. Preferably it is 17 mass% or less, More preferably, it is 16.5 mass% or less, Most preferably, it is 16.0 mass% or less. When the 45 μm sieve residue is 17% by mass or less, the long-term strength development of the mixed cement is further improved.
In addition, the 45-micrometer sieve residue amount can be measured according to the screen sieve method of "JIS A6201 (fly ash for concrete)".

The content of free lime in the coal ash is preferably 1.5% by mass or less, more preferably 0.1 to 1.0% by mass. When the free lime content is 1.5% by mass or less, the strength development of the mixed cement is further improved.
The content of free lime can be measured according to “JIS R 5202 (Portland cement chemical analysis method)”.
The amount of water-soluble boron in the coal ash is preferably 120 mg / kg or less, more preferably 110 mg / kg or less, still more preferably 100 mg / kg or less, and particularly preferably 90 mg / kg or less. When the amount of the water-soluble boron is 120 mg / kg or less, the initial strength development of the mixed cement is further improved.

The mass ratio of the amount of free lime to the amount of water-soluble boron in coal ash (free lime / water-soluble boron) is preferably 8 or more, more preferably 9 or more, and particularly preferably 10 or more. When the mass ratio is 8 or more, the initial strength development of the mixed cement is improved.
The amount of water-soluble boron can be measured by the following procedure.
(1) 25 g of coal ash is added to 75 cm ³ of distilled water and stirred for 10 minutes while adjusting the pH to 8.5 ± 0.2. In addition, hydrochloric acid or sodium hydroxide aqueous solution is used for pH adjustment.
(2) After stirring, solid-liquid separation is performed, and the boron concentration in the liquid is quantified by ICP to calculate the amount of water-soluble boron.

The vitrification rate of coal ash is preferably 60% by mass or more, more preferably 65% by mass or more, and particularly preferably 70% by mass or more.
The basicity of the glass phase of coal ash is preferably 0.4 or more, more preferably 0.5 or more, and particularly preferably 0.6 or more. By using coal ash whose vitrification rate and basicity of the glass phase are within the above ranges, it is possible to improve the long-term strength development of the mixed cement.
The vitrification rate of coal ash and the basicity of the glass phase can be calculated by the method described in JP 2011-132046.
The Blaine specific surface area of the coal ash is preferably 3,300 to 8,000 cm ² / g, more preferably 3,500 to 5,000, from the viewpoint of fluidity of mortar using mixed cement and strength development of the mixed cement. 7,000 cm ² / g.

In the present invention, the proportion of coal ash in 100% by mass of the mixed cement is preferably 5 to 60% by mass, more preferably 10 to 55% by mass, and particularly preferably 15 to 58% by mass.
Even within the above range, from the viewpoint of strength development, the proportion of coal ash in 100% by mass of the mixed cement is preferably 45% by mass or less, more preferably 40% by mass or less.
From the viewpoint of promoting the use of coal ash, the proportion of coal ash in 100% by mass of the mixed cement is preferably 40% by mass or more, and more preferably 45% by mass or more.
The mixed cement of the present invention can increase the blending amount of coal ash while maintaining the quality of the mixed cement.

The mixed cement of the present invention may further contain limestone fine powder as a cement mixed material.
The content of calcium carbonate in the limestone fine powder is preferably 90% by mass or more, more preferably 95% by mass or more, and the content of aluminum oxide is preferably 1.0% by mass or less. If the calcium carbonate content is 90% by mass or more and the aluminum oxide content is 1.0% by mass or less, the strength development of the mixed cement is further improved.
The Blaine specific surface area of the limestone fine powder is preferably 4,000 cm ² / g or more, more preferably 5,000 to 12,000 cm ² / g, still more preferably 6,000 to 11,000 cm ² / g, particularly preferably. 8,000 to 11,000 cm ² / g. When the brain specific surface area is 4,000 cm ² / g or more, the strength development of the mixed cement is further improved.
In the present invention, the proportion of fine limestone powder in 100% by mass of the mixed cement is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 12% by mass or less.
In addition, when a plurality of types of cement mixed materials (blast furnace slag fine powder, coal ash, limestone fine powder, etc.) are used, the total proportion of the cement mixed material (for example, blast furnace slag fine powder and The total proportion of coal ash is preferably 5 to 80% by mass, more preferably 30 to 80% by mass, and particularly preferably 40 to 60% by mass.

In the present invention, the method of mixing the cement and the cement mixed material is not particularly limited, and (i) a method of mixing the fired product (clinker), gypsum and the cement mixed material while pulverizing them simultaneously, (ii) Examples thereof include a method of mixing pulverized cement with a previously pulverized cement mixed material.

A paste, mortar or concrete is prepared by mixing the cement or mixed cement of the present invention, water, and other materials blended as required (for example, fine aggregate, coarse aggregate, water reducing agent, etc.). can do.
When preparing mortar or concrete, as aggregate, normal fine aggregate (eg river sand, land sand, crushed sand, etc.) and coarse aggregate (eg river gravel, mountain gravel, etc.) used in the production of mortar and concrete. Crushed stone, etc.) can be used.
As the water reducing agent, lignin-based, naphthalenesulfonic acid-based, melamine-based, and polycarboxylic acid-based water reducing agents (including AE water reducing agents, high-performance water reducing agents, and high-performance AE water reducing agents) can be used.
In addition, you may use admixtures, such as an air entrainment agent and an antifoamer, in the range which does not have trouble if needed.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
1. Production and evaluation of calcined products 1-20 Mainly used as raw materials for calcined products, mainly limestone, clay, silica, iron materials, etc., which are conventionally used as the main raw materials for Portland cement clinker, and alternative raw material waste The raw materials were prepared so that the hydraulic rate (HM), silicic acid rate (SM), and iron rate (IM) of the fired product were the values shown in Table 2. .
Here, Table 1 shows the blending amount (kg) per 1 ton (represented as “t” in the table) of the raw material substitute waste used as the raw material of the fired product 11. The fired product 11 is a fired product having a hydraulic modulus (HM), a silicic acid rate (SM), and an iron rate (IM) equivalent to those of a commercially available early strong Portland cement clinker.
In addition, the raw material substitute waste used for other fired products (fired products 1 to 10, 12 to 20) is the raw material substitute waste shown in Table 1 in order to obtain a fired product having the desired hydraulic modulus. Of wastes other than coal ash and recycled iron raw materials (recycled limestone, recycled clay, construction generated soil, and recycled silica) are fixed as much as possible, and the usage of coal ash and recycled iron raw materials is reduced. It is adjusted.
Table 1 shows a breakdown of raw material substitute waste (used amount: 165 kg / t (fired product)) that is generally used as a raw material of the fired product that is a material of early strong cement.
In Table 2, the usage amount of the raw material alternative waste represents an increased amount based on the usage amount of the raw material alternative waste used in Firing Example 11.

1) Evaluation of the amount of raw material alternative waste used The amount of raw material alternative waste used in the production of each calcined product is based on the amount of raw material alternative waste used in Firing Example 11 (165.0 kg / ton) In addition, the burned product increased by 20 kg / ton or more was evaluated as “◯” because the amount of waste used was sufficiently increased. The results are shown in Table 2.
From the results of Table 2, when the silicic acid ratio (SM) of the fired product exceeds 2.48, or when the amount of C ₃ S exceeds 70.0% by mass, use of raw material alternative waste of the fired product It turns out that evaluation of quantity worsens.

2. Production and evaluation of cement [Examples 1 to 7, Comparative Examples 1 to 13]
With respect to 100 parts by mass of each fired product in Table 2, drained dihydrate gypsum (manufactured by Sumitomo Metals) and hemihydrate gypsum obtained by heating the drained dihydrate gypsum at 140 ° C., 100% by mass of cement The ratio of gypsum (dihydrate gypsum and hemihydrate gypsum) is 2.7% by mass in terms of SO ₃ , and the brain specific surface area is 4500 ± 50 cm ² / g in a batch type ball mill. The cement was prepared by simultaneous grinding as described above. The ratio of hemihydrate gypsum to the total amount of dihydrate gypsum and hemihydrate gypsum was 50% by mass in terms of SO ₃ in all cements.

The following properties were evaluated using each cement.
1) Evaluation of pulverizability of the fired product Table 3 shows the brane specific surface area of each cement and the time required to reach the brane specific surface area.
The evaluation of grindability was based on the time required to produce the cement of Comparative Example 4 (cement using a fired product 11 equivalent to a commercial product), and the time multiplied by 1.1 (127 Cement less than (min) was rated as “◯”. The results are shown in Table 4.
2) Evaluation of setting properties The setting time of each cement was measured according to "JIS R 5201 (physical test method for cement)". The results are shown in Table 3.
The evaluation of the setting property is based on the setting start time and the setting time of the cement of Comparative Example 4 (cement using the burned material 11 equivalent to the commercial product), and the setting start time is 100 minutes or more, and the setting is completed. Those with a time of 150 minutes or more were evaluated as “◯”. The results are shown in Table 4.

3) Evaluation of mortar compressive strength About the mortar compressive strength of the mortar containing each cement, it measured based on "JISR5201 (physical test method of cement)". The results are shown in Table 3.
The evaluation of the mortar compressive strength is based on the mortar compressive strength of the mortar containing the cement of Comparative Example 4 (cement using the fired product 11 equivalent to the commercial product), and the age of each mortar containing the cement of Comparative Example 4 Mortar compressive strength greater than or equal to the value obtained by multiplying the compressive strength by 0.95 (material age 1 day: 24.7 N / mm ² or more, material age 3 days: 44.8 N / mm ² or more, material age 7 days: 55 .3 N / mm ² or higher, material age 28 days: 64.0 N / mm ² or higher) was evaluated as “◯”. The results are shown in Table 4.

4) Evaluation of fluidity About the mortar of the following mixing | blendings, the mortar left still for 30 minutes after kneading | mixing is thrown into a flow cone (upper surface diameter 5cm, lower surface diameter 10cm, height 15cm), and a flow cone is upwards. The spread of the mortar when removed was measured to determine the flow value. The fluidity was evaluated using a numerical value immediately after kneading (hereinafter also referred to as “immediate value”) and a change with time (hereinafter also referred to as “loss rate”) calculated using the following evaluation formula. In the evaluation of fluidity, the value immediately after 250 mm or more and the loss rate of 30% or less was evaluated as “◯”. The results are shown in Tables 3 and 4.
[Combination]
Water / cement (mass ratio): 0.35
Fine aggregate / cement (mass ratio): 2.0
Water-reducing agent (“Neo build SP8N” / cement (mass ratio): 0.0065
[Evaluation formula for change over time (loss rate)]
Amount of change with time (loss rate): {(f ₁ −f ₂ ) / (f ₁ −100)} × 100 (%)
(In the formula, f ₁ represents the flow value (mm) of the mortar immediately after kneading, and f ₂ represents the flow value (mm) of the mortar left standing for 30 minutes after kneading.)

[Examples 8 to 13, Comparative Examples 14 to 17]
In Examples 8 to 13 and Comparative Examples 14 to 17, the fired product 6 in Table 2 was used as a fired product (clinker).
To 100 parts by mass of the fired product, drained dihydrate gypsum (manufactured by Sumitomo Metals Co., Ltd.) and hemihydrate gypsum obtained by heating the drained dihydrate gypsum at 140 ° C. are added at a ratio shown in Table 5. Then, cement was prepared by simultaneous grinding for 118 minutes in a batch type ball mill.
The specific surface area of Blaine is more varied than Examples 1 to 8 and Comparative Examples 1 to 12 due to the effect of the amount of gypsum added, but the variation is similar to the normal variation of commercial products.

In the same manner as in Examples 1 to 7 and Comparative Examples 1 to 13, the setting time of each cement, the flow value of the mortar left standing immediately after kneading and 30 minutes after kneading were measured, and the setting properties of each cement and each cement were measured. The fluidity of the containing mortar was evaluated. The results are shown in Table 5.

From Tables 4 and 5, according to the cement of the present invention, the amount of raw material substitute waste can be increased, and quality equivalent to that of commercially available early strong Portland cement can be secured.

3. Production of cements 1 to 3 In the same manner as the production of the calcined products 1 to 20, the hydraulic rate (HM), silicic acid rate (SM), and iron rate (IM) of the calcined product are obtained. The raw materials were prepared so that the values shown in Table 6 were obtained.
With respect to 100% by mass of the obtained fired product, exhausted dihydrate gypsum (manufactured by Sumitomo Metals) and hemihydrate gypsum obtained by heating the exhausted dihydrate gypsum at 140 ° C. Cement 1 was prepared by adding an amount such that the proportion of gypsum (dihydrate gypsum and hemihydrate gypsum) was 2.2% by mass in terms of SO ₃ and simultaneously grinding using a batch-type ball mill.
Cements 2 and 3 were prepared in the same manner as cement 1 except that the gypsum ratio was changed from 2.2% by mass to 2.7% by mass in terms of SO ₃ .
The ratio of hemihydrate gypsum to the total amount of dihydrate gypsum and hemihydrate gypsum was 50% by mass in terms of SO ₃ in all cements.

[Examples 14 to 29, Comparative Examples 18 to 24]
Cement, blast furnace slag fine powder, coal ash, and fine limestone powder described in Tables 6 to 9 were mixed with stirring using a ball mill with the composition described in Table 10 and with a reduced amount of media (balls). Cement containing no cement mixture (cement compositions 1 to 3) or mixed cement (cement compositions 4 to 23) was prepared.
The mortar compressive strength at the age of 3 days, 7 days and 28 days of each obtained cement composition was measured according to “JIS R 5201 (physical test method for cement)”. The results are shown in Table 11.
In addition, as Reference Examples 1 to 4, blast furnace cement B type (cement in which blast furnace slag fine powder in 100% by mass of cement exceeds 30% by mass and 60% by mass or less), blast furnace cement C type (in 100% by mass of cement) Blast furnace slag fine powder of more than 60% by mass and cement of 70% by mass or less), fly ash cement A type (cement in which 100% by mass of coal ash exceeds 5% by mass and less than 10% by mass) Table 11 shows JIS standard values of mortar compressive strength of fly ash cement type C (cement in which coal ash in cement of 100% by mass exceeds 20% by mass and is 30% by mass or less).

In Table 7, blast furnace slag fine powder 1 is a common blast furnace slag fine powder for cement mixture, and blast furnace slag fine powder 2 is a pulverized product of slow-cooled slag. The 28-day activity index of blast furnace slag fine powder in Table 7 was determined in accordance with “JIS A 6206 Annex (normative) (Activity index and flow value ratio test method by mortar of blast furnace slag fine powder)”. .
Moreover, in Table 8, coal ash 1 is a fly ash type II equivalent of “JIS A 6201 (fly ash for concrete)” which is a general coal ash for cement mixture, and coal ash 2 is “JIS A 6201 (fly ash for concrete) "is a fly ash type IV equivalent product. The 28-day activity index of coal ash in Table 8 was determined according to “JIS A 6201 Annex 2 (normative) (flow value ratio and activity index test method using fly ash mortar)”.

From Table 11, when Example 14 and Comparative Example 18 are compared, the proportion of general blast furnace slag fine powder (blast furnace slag fine powder 1 shown in Table 7) is 40% by mass in 100% by mass of the mixed cement. It can be seen that the mixed cement (Example 14) has the same strength development as the ordinary cement (Comparative Example 18).
When Example 15 and Comparative Example 21 are compared, a mixed cement (implementation) in which the proportion of low-quality blast furnace slag fine powder (blast furnace slag fine powder 2 shown in Table 7) is 40% by mass in 100% by mass of the mixed cement. Example 15) has an initial strength development property (a mortar compressive strength of 3 days and 7 days of age) equivalent to the normal blast furnace cement of Comparative Example 21 (a mixture of ordinary cement and blast furnace slag 1). I understand.
From Examples 16 to 19 and Reference Example 1, the mixed cement (Examples 16 to 19) in which the proportion of fine blast furnace slag fine powder was 40 or 60% by mass in 100% by mass of the mixed cement was “JIS”. R 5211 (Blast Furnace Cement) "has better initial strength than the JIS standard value of B type blast furnace cement B (Reference Example 1) (3 and 7-day mortar compressive strength), equivalent It has strength development properties at 28 days of age.
From Example 20 and Reference Example 2, the mixed cement (Example 20) in which the ratio of the low-grade blast furnace slag fine powder is 70% by mass in 100% by mass of the mixed cement is “JIS R 5211 (blast furnace cement)”. Has better initial strength development (3 and 7-day mortar compressive strength) than blast furnace cement type C (Reference Example 2), and has equivalent strength development at 28 days of age. .

When Example 21 and Comparative Example 18 are compared, the mixed cement (Example 21) in which the proportion of general coal ash (coal ash 1 shown in Table 8) is 30% by mass in 100% by mass of the mixed cement. It can be seen that it has an initial strength development property (a mortar compressive strength of 3 days and 7 days of age) equivalent to that of ordinary cement (Comparative Example 18).
From Examples 22 to 23 and Reference Example 3, mixed cement (Examples 22 to 30) in which the proportion of low-quality coal ash (coal ash 2 shown in Table 8) is 30% by mass in 100% by mass of the mixed cement. It can be seen that No. 23) has a strength developability equal to or higher than the standard value (reference example 3) of the fly ash cement A type of “JIS R 5213 (fly ash cement)”.
From Examples 24-27 and Reference Example 4, the mixed cement (Examples 24-27) in which the proportion of low-quality coal ash is 40 or 50% by mass in 100% by mass of the mixed cement is “JIS R 5213 ( It can be seen that the fly ash cement has a strength development property equal to or higher than the standard value of the fly ash cement C type (Reference Example 4).

Claims

(A) The hydraulic modulus (HM) is 2.10 to 2.30, the silicic acid ratio (SM) is 1.80 to 2.48, and the iron ratio (IM) is 1. A cement containing 3 to 2.6 and a pulverized product of calcined product in which the ratio of 3CaO · SiO 2 in 100% by mass of calcined product is 70.0% by mass or less as calculated by the Borg formula, and gypsum Because
The ratio of gypsum in 100% by mass of the cement is 1.2% by mass or more in terms of SO 3 , and the ratio of hemihydrate gypsum to the total amount of dihydrate gypsum and hemihydrate gypsum in the cement is SO Cement characterized by being 30% by mass or more in terms of 3 .
The cement according to claim 1, wherein the fired product is fired using at least one of waste and generated soil as a part of the raw material.
The method for producing cement according to claim 1 or 2, wherein at least one of waste of 300 kg or less and generated soil is used as a part of raw material per ton of the fired product. Method.
A mixed cement comprising the cement according to claim 1 or 2, and (B) a cement mixed material containing at least one of blast furnace slag fine powder and coal ash.
The mixed cement according to claim 4, wherein the proportion of the cement mixed material in the mixed cement is 5 to 80% by mass.
The mixed cement according to claim 4 or 5, wherein the 28-day activity index of the cement mixed material is 50% or more.
The mixed cement according to any one of claims 4 to 6, further comprising fine limestone powder as the cement mixed material.
The method for producing a mixed cement according to any one of claims 4 to 7, wherein at least one of waste of 300 kg or less and generated soil is used as a part of raw material per 1 ton of the fired product. A method for producing a mixed cement.