JP6629632B2 - Fly ash cement composition - Google Patents

Description

The present invention is a fly ash cement that can be used for general civil engineering work, foundation work of a general building, grouting work, etc., and has at least a part of the characteristics of a conventional fly ash cement such as excellent workability and initial strength. expressing concerns fly ash cement composition strength enhancing properties with good fly ash cement.

  Fly ash cement, in which part of the cement is replaced with fly ash, has a lower heat of hydration, superior workability, greater long-term strength, greater water tightness and chemical resistance, less drying shrinkage, etc. compared to plain cement It has various advantages such as reducing the use of cement clinker, reducing the amount of carbon dioxide emissions, and effectively using fly ash as a resource, which leads to a reduction in the environmental load. It is frequently used for mass concrete for dams and harbor construction.

  According to the JIS standard, according to the amount of fly ash mixed, each of Class A (more than 5 and 10% or less), Class B (more than 10 and 20% or less), and Class C (more than 20 and 30% or less) Fly ash cement is specified. Of these varieties, the B type is common and is widely used.

  However, it has been pointed out that these fly ash cements also have a disadvantage that their initial strength is lower than that of plain cement. For this reason, various measures have been studied, such as increasing the fineness, using in combination with a strength enhancer such as silica fume or potassium carbonate, curing at high temperature, and activating fly ash by acid treatment.

  For example, Patent Document 1 discloses that a cement base consisting of 100 parts by mass of Portland cement and 10 to 40 parts by mass of fly ash has a mass ratio of aluminum sulfate to alkaline earth metal nitrate of 2: 1 to 1: 3. There is described a fly ash cement composition characterized by adding 1.0 to 3.0% by mass of a setting accelerator consisting of a combination.

  On the other hand, early-strength Portland cement is known as a cement with good strength development, but fly ash cement using this as a base cement is not practical because it lacks practicality in terms of price and supply compared to ordinary Portland cement. Not converted.

  Recently, a study has been made focusing on the mineral composition of the cement clinker, returning to the cement clinker constituting the base cement.

For example, Patent Document 2, _C 3 S> _70% in the calculated value mineral composition of the cement clinker by Borg _formula, C 2 S _<5%, of free lime content in the cement clinker is 0.5 to 7.5 % by weight of highly active cement clinker, high activity cement produced by adding gypsum to the high active cement clinker so that 1.5 to 4.0 wt% converted to sO ₃ is described.

JP 2007-131377 A Japanese Patent No. 5747407

  The above methods of increasing the fineness, curing at high temperature, and activating fly ash by acid treatment increase the energy cost and labor.

  Further, in the method using a third component other than cement and fly ash as described in Patent Document 1, depending on the use environment, even if the initial strength expression is improved, it is not easy to control the fresh property or fly ash There is a possibility that the above-mentioned merit due to the incorporation of the above may be hindered.

  Patent Literature 2 studies addition of blast furnace slag and gypsum to highly active cement, but does not sufficiently study fly ash cement using high active cement. Furthermore, even if the highly active cement is used as a base cement for fly ash cement, the initial strength at 3 days of age is sufficiently higher than that of conventional fly ash cement, but the strength increase up to 28 days of age is small. There is no guarantee that it will be significantly higher than conventional fly ash cement.

The present invention has been made in view of the problems described above, the cement clinker used can be manufactured stably, the initial strength manifestation is better than conventional fly ash cement, and the strength at the age of 28 days. and to provide a fly ash cement composition using fly ash cement can be sufficiently secured.

The present invention is a related invention of the highly active cement described in Patent Literature 2, and the present inventor has proposed a high active cement clinker described in Patent Literature 2 in which the mineral composition in the cement clinker (particularly, C ₃ S Amount and C ₂ S amount and their ratio) and free lime amount, it is possible to obtain a cement that can be manufactured stably and has good initial strength development and strength enhancement properties. As a substitute for ordinary Portland cement used as a base cement for ash cement, a fly ash cement having good initial strength can be obtained, and it has been found that the object of the present invention can be achieved, and the present invention has been completed. .

The invention according to claim 1 of the present application relates to a method for producing a fly ash cement as a base cement of fly ash, which has a C ₃ S content of 60 to 71% and a C ₂ S It has a clinker mineral composition in which the amount is 1% or more, the total amount of C ₃ S and C ₂ S is 70 to 80%, the C ₃ S / C ₂ S amount ratio is 7 to 50, and the amount of free lime is 1. In a fly ash cement using cement obtained by adding gypsum to an alite-rich clinker of 0 to 4.0% by weight , blast furnace slag fine powder and / or limestone fine powder in a total amount of 2 to 10 are divided. Weight% fly ash cement composition ".

The fly ash cement used in the fly ash cement composition of the present invention is obtained by mixing fly ash with base cement. The blending ratio of fly ash is not particularly limited, and it may be blended in accordance with, for example, each type of A to C specified by JIS standards. Among them, a composition corresponding to the fly ash cement B type is preferable because both the above-mentioned environmental load reduction property and the securing of the initial strength can be achieved at the same time. The production of fly ash cement may be performed according to a conventional method.

  The cement as the base cement is obtained by adding gypsum to a clinker containing high alite. The gypsum is not particularly limited as long as it has been conventionally used for the production of cement, such as gypsum dihydrate or anhydrous gypsum.

Amount of gypsum, 1.5 to 4.0 wt% is preferred converted to SO ₃ to alite-rich clinker. If the content is less than 1.5% by weight, fresh properties such as fluidity and coagulation properties at the initial stage of hydration are deteriorated, and there is a possibility that workability may be impaired. On the other hand, when the content exceeds 4.0% by weight, the strength increase until the material age of 28 days is so small that the strength of the material age of 28 days may not be secured.

The fineness of the cement is not particularly limited, but is preferably in the range of 3500 to 5500 (cm ² / g) in terms of Blaine value. Needless to say, the higher the fineness, the higher the strength developability, but if the fineness is too high, the increase in strength up to the age of 28 days may be small, and if the fineness is too low, the initial strength is secured. It may be difficult. In order to achieve the object of the present invention economically, it is preferable that the Blaine value is about 3700 to 4700 (cm ² / g).

The clinker having a high alite content has a C ₃ S amount of 60 to 71%, a C ₂ S amount of 1% or more, and a combined amount of C ₃ S and C ₂ S of 70 to 80%, obtained by the Borg equation. _It has a specific clinker mineral composition such as a ₃ S / C ₂ S content ratio of at least 7 to 50. As described above, by balancing the amount of C ₃ S and the amount of C ₂ S in the clinker, a stable clinker can be produced, and a cement having good initial strength development property and strength enhancement property can be obtained.

_{C 3} S content in the clinker is 60 to 71%. When the amount of C ₃ S is less than 60%, it is difficult to obtain a cement having good fresh properties at the initial stage of hydration and good initial strength development and strength enhancement properties, and in some cases, sufficient strength at a material age of 28 days. It becomes difficult to do.

Further, when the C ₃ S amount exceeds 71% by weight, the C ₂ S amount and the amount of the interstitial phase (aluminate phase) are relatively reduced, so that it may be difficult to produce a stable clinker depending on the firing method. is there. Further, the increase in strength up to the age of 28 days may be small, and it may be difficult to secure the strength at the age of 28 days.

The C ₂ S content in the clinker is 1% or more. If the amount of C ₂ S is less than 1%, the amount of the interstitial phase (aluminate phase) becomes excessive, and the fresh properties and the strength enhancing properties may be deteriorated. On the other hand, if the amount of the interstitial phase (aluminate phase) is too large, the increase in strength up to the age of 28 days becomes small, and it may be difficult to secure the strength at the age of 28 days.

The total amount of the _{C 3} S and the _{C 2} S in the clinker is 70-80%. If it is less than 70%, the amount of the interstitial phase (aluminate phase) becomes relatively large, so that sufficient initial strength cannot be obtained, or even if sufficient initial strength is obtained, the above-mentioned fresh properties deteriorate. In some cases, the strength-enhancing property is poor, and the strength at the age of 28 days cannot be sufficiently secured.

  On the other hand, if it exceeds 80%, the amount of the interstitial phase (aluminate phase) becomes relatively too small, and depending on the sintering method, it becomes difficult to produce a stable clinker, or it becomes impossible to obtain a sufficient initial strength.

The C ₃ S / C ₂ S ratio in the clinker is important from the viewpoints of securing the initial strength and enhancing the strength. In the present invention, the C ₃ S / C ₂ S ratio is at least 7 to 50. If it is less than 7, the amount of C ₂ S becomes relatively large, so that the securing of the initial strength becomes insufficient. On the other hand, if it exceeds 50, the amount of C ₂ S is relatively reduced, and the strength-enhancing property is deteriorated, and it may be difficult to secure the strength at a material age of 28 days.

In the present invention, it is an object of the present invention to obtain a fly ash cement in which the cement clinker used can be manufactured stably and has a good initial strength development property and a sufficient strength at a material age of 28 days more than conventional fly ash cement. However, specifically, for example, in the case of fly ash cement type B, the mortar strength in a compressive strength test based on JIS R 5201 is 30.0 (N / mm ² ) or more at 3 days of age, and 28 days of age. Is set to 55.0 (N / mm ² ) or more, and is used as a criterion for quality judgment. Therefore, "good initial strength development" referred to in the present specification means, for example, that in the case of fly ash cement B type, the above-mentioned numerical value at the age of 3 days is satisfied, and "the strength at the age of 28 days""Also ensure sufficient" means satisfying the above-mentioned numerical value at the age of 28 days.

The amount of free lime in clinker is important from the viewpoint of stable production of clinker, securing of initial strength, stimulant for enhancing hydration activity of C ₃ S, and needs to be tightly controlled. When the content is 1.0 to 4.0% by weight, each performance in the above viewpoint can be obtained, and the object of the present invention can be easily achieved.

  Fly ash is not particularly limited as long as it has been conventionally used for fly ash cement, cement admixture, and the like. For example, it is specified in JIS A 6201, and among them, high quality Class I or Class II is preferable.

The invention according to claim 2 of the present application is directed to the invention according to claim 1, wherein the clinker having a high alite content has a clinker mineral composition having a C ₂ S amount determined by a Borg equation of 1 to 15%. Fly ash cement composition ".

As described above, a certain amount of C ₂ S is required in the clinker from the viewpoints of fresh properties, strength enhancement properties, stable clinker production, and the like, but it is not preferable to exceed 15%. If it exceeds 15%, the amount of C ₃ S and / or the amount of the interstitial phase (aluminate phase) is relatively reduced, so that the strength development in the initial to middle stages is deteriorated, and the object of the present invention cannot be achieved. There are cases . Good more preferable amount is 4% to 10%. Within this range, an economical and stable clinker can be produced, and the strength expression can also achieve the object of the present invention.

The invention according to claim 3 of the present application, the "the alite-rich clinkers, according to claim 1 or ₂ C ₃ S / C 2 S content ratio and having a clinker mineral composition of 7-20 Fly ash cement composition ".

As described above, the C ₃ S / C ₂ S amount ratio (balance between the C ₃ S amount and the C ₂ S amount) is important for achieving the object of the present invention, and it is necessary to set the ratio at least 7 or more. It is preferably from 7 to 55, and more preferably from 7 to 20. If the balance between the C ₃ S amount and the C ₂ S amount is good, clinker production becomes easy, and the above-mentioned target strength can be secured at the age of 3 days and 28 days, and the long-term strength is expected to increase. it can.

The invention according to claim 4 of the present application, "the in alite-rich clinker, C ₃ A content is 8% to 12% as determined by Borg formula, C ₄ AF weight 7% -10% and C ₃ A and C ₄ The clinker mineral composition having a total amount of AF of 18 to 19% and a C ₃ A / C ₄ AF amount ratio of 0.9 to 1.5, according to any one of claims 1 to 3, Described fly ash cement composition ".

As described above, the amount of C ₃ S and the amount of C ₂ S are important in the present invention, but in order to secure the initial strength, obtain good fresh properties, and perform stable clinker production, C ₃ A in the clinker is used. It is preferable to control the amount and the C ₄ AF amount.

In the clinker having a high alite content, the C ₃ A amount is preferably 8 to 12%. If the amount of C ₃ A is less than 8%, it may be difficult to secure the initial strength easily depending on the use environment of the cement composition of the present invention, such as low air temperature and water temperature of the kneading water. On the other hand, if it exceeds 12%, the fresh properties may deteriorate and workability may be impaired depending on the use environment of the cement composition of the present invention, such as a high temperature of the kneading water or a high temperature of the kneading water.

In the clinker having a high alite content, the C ₄ AF amount is preferably 7 to 10%. If the amount of C ₄ AF is less than 7%, the amount of interstitial phase may be so small that clinker production may be difficult. In addition, when the content exceeds 10%, the amount of C ₃ A is relatively reduced, and the initial strength is difficult to easily secure depending on the use environment of the cement composition of the present invention, such as a low air temperature or a low kneading water temperature. There is.

The total amount of the C ₃ A and C ₄ AF is preferably 18 to 19%. Within this range, clinker production becomes easy even when the content of alite (C ₃ S) is high.

Further, in the clinker having a high content of alite, the C ₃ A / C ₄ AF amount ratio is preferably 0.9 to 1.5. By setting the balance between the C ₃ A amount and the C ₄ AF amount in this range, stable clinker production can be performed while securing a predetermined C ₃ A amount.

The fly ash cement used in the fly ash cement composition of the present invention may be, if necessary, a blast furnace as long as it does not significantly impair strength development properties or hydration properties (fresh properties) immediately after kneading by adding kneading water. Chemical admixtures such as slag fine powder, limestone fine powder, anhydrous gypsum, gypsum dihydrate, silica fume, expanding ingredients such as CSA, and other conventionally used cement admixtures, shrinkage reducers, setting regulators, pH regulators, etc. And may be used as a fly ash cement composition.

  For example, one is a fly ash cement composition obtained by adding a blast furnace slag fine powder and / or a limestone fine powder in a total amount of 2 to 10% by weight to the above fly ash cement.

The blast furnace slag fine powder is not particularly limited as long as it has been conventionally used for a cement admixture or the like. Among them, those having a Blaine value of about 4000 to 12000 (cm ² / g) are preferable. By adding blast furnace slag fine powder, it is possible to effectively utilize blast furnace slag and reduce the environmental load, and to obtain fly ash cement having good strength-enhancing properties.

The limestone fine powder is not particularly limited as long as it is conventionally used as a constituent material of a cement composition, a cement admixture, or concrete. Among them, the Blaine value is preferably 2000 to 10000 (cm ² / g). By adding the limestone fine powder in this range, not only the initial material age but also the strength of the long-term material after 28 days can be effectively increased.

  The blast furnace slag fine powder and the limestone fine powder may be added to the fly ash cement in combination.

  The amount added to these fly ash cements is preferably 2 to 10% by weight in total. If the amount is less than 1% by weight, the amount is too small to obtain a sufficient effect of addition. If the content exceeds 10% by weight, the initial strength expression may deteriorate or the effect of adding fly ash may be impaired.

The fly ash cement used for the fly ash cement composition of the present invention has a good initial strength development property more than the conventional fly ash cement and can sufficiently secure the strength at the age of 28 days, and the strength development property is improved. Thus, products equivalent to Classes A to C of the JIS standard can be obtained. Further, since the clinker containing high alite used for the base cement can be manufactured stably, the hydration performance becomes uniform and stable.

Fly ash cement compositions of the present invention using the above notated fly ash cement is a good thing on the notated fly ash cement as well as the initial strength development, also environmental load since the reduce the amount of cement It has good reducibility.

Hereinafter, the full fly ash cement compositions of the present invention will be described in more detail.

[Fly ash cement]
The fly ash cement used for the fly ash cement composition of the present invention is basically a base cement such as ordinary Portland cement in a conventional fly ash cement replaced with a cement using an alite-rich clinker described below. Things.

  Therefore, depending on the mixing ratio of fly ash, JIS-standard equivalents, B-class equivalents, and C-class equivalents are included. Depending on the quality of fly ash, JIS-standard I-class and II-class are used. And those corresponding to various conventional fly ash cements.

The fly ash cement used in the fly ash cement composition of the present invention has a higher strength development than conventional ones, and in particular, the initial strength, which was a weak point of the conventional fly ash cement, can be secured. This is a highly versatile product that can be used in various fields, such as general civil engineering work, general building foundation work, and grouting work.

  The production of the fly ash cement may be carried out by mixing the following cement and the following fly ash at a predetermined ratio (a ratio according to any one of Classes A to C of JIS standard) by a conventional method.

If necessary, a third component such as blast furnace slag powder, limestone fine powder or gypsum may be added to the fly ash cement composition within a range that does not significantly impair the strength development. Hereinafter, each constituent material of the fly ash cement used in the fly ash cement composition of the present invention will be described.

[Components of fly ash cement]
A. Base Cement The cement as the base cement used in the present invention is obtained by adding a predetermined amount of the following gypsum to the following clinker containing high alite and mixing and pulverizing the same. In addition, a clinker having a content of C ₂ S of less than 1% and an amount of free lime in the clinker of more than 4% by weight is mixed and / or separated and pulverized with a clinker containing high alite to produce the cement of the present invention. Is also good. The production apparatus and the production method of the cement may be the same as the conventional ones.

The fineness of the cement is not particularly limited, but may be about 3500 to 4700 (cm ² / g) in terms of Blaine value. If it is used as a high-strength fly ash cement, it is preferably at least 3700 (cm ² / g).

[Clinker with high content of alite]
(1) Clinker mineral composition The clinker having a high alite content used in the present invention has a C ₃ S content of 60 to 71% and a C ₂ S content of 1% or more (preferably 1 to 15%, more preferably) determined by the Borg equation. 4 to 10%) and in a total amount 70 to 80 percent of the _{C 3} S and _{C 2 S,} clinker mineral composition of _C 3 S / C ₂ S content ratio of at least 7 to 50 (preferably 7 to 20) It has.

The mineral composition is as described above. Except for C ₃ S and C ₂ S, it is composed of a porous phase mainly composed of calcium aluminate, and the porous phase contains minerals such as C ₃ A and C ₄ AF.

_{C 3} A and _C 4 AF in the gap membrane phase, the total amount of _{C 3} A content is 8% to 12% and _C 4 AF weight 7% -10% and _{C 3} A and _C 4 AF obtained by Borg formula It preferably has a clinker mineral composition of 18 to 19% and a C ₃ A / C ₄ AF amount ratio of 0.9 to 1.5. Such a mineral composition is preferable as described above.

  The Borg equation used in the present invention is an equation conventionally used to calculate the main mineral composition in cement clinker, and the ratio of each mineral is calculated from the analysis result of the chemical composition of cement clinker. Since the obtained ratio is a calculated value based on the analysis result of the chemical composition, it does not match the actual ratio in the cement clinker. In addition,% is mass%.

<Borg type>
_{C 3 S (%) = (} 4.07 × CaO%) - (7.60 × SiO 2%) - (6.7 × Al 2 O 3%) - (1.43 × Fe 2 O 3%) - (2.85 × SO ₃ %)
C ₂ S (%) = (2.8 × 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 %
C ₃ S is a mineral that mainly develops cement strength from the initial material age to the long-term material age, and the more this is, the higher the strength and the faster the strength. The larger the amount of generated, the more difficult it is to fire, for example, high-temperature firing or a sufficient firing time is required.

C ₂ S does not contribute much to the strength development at the early age, but contributes to the strength development at the middle to long term age because hydration is continued for a long time. Therefore, it is necessary to some extent to improve the strength. It is also indispensable for stable clinker firing. Furthermore, the more this is, the better the chemical resistance and drying shrinkage are.

C ₃ A has a high hydration activity and greatly contributes to strength development at an early age. However, when the content is large, the fresh properties such as rapid hardening are deteriorated, and the strength enhancing property is also deteriorated.
Although C ₄ AF has no remarkable feature in hydration performance, it contributes to easy firing and stable firing as a porous phase in clinker firing.

In the clinker, other than the above-mentioned C ₃ S, C ₂ S, C ₃ A, and C ₄ AF, other aluminate-based minerals, aluminosilicate-based minerals, amorphous interstitial phases, and the like exist depending on manufacturing conditions. I do.

(2) Free lime It is important to control the amount of free lime from the viewpoints of stable production of clinker, stimulants for enhancing the hydration activity of C ₃ S, and the like. Further, if free lime is present, the calorific value in the initial stage of hydration increases, and the temperature increases, so that the initial strength increases. However, if the amount is too large, there is a possibility of causing expansion, a decrease in fluidity, popping out, weathering of the clinker, and the like.

  In the present invention, the amount of free lime in the clinker is 1.0 to 4.0% by weight. Within this range, it becomes easy to obtain only the above-described positive effect due to the inclusion of free lime in the clinker.

(3) Production of clinker The production of the clinker having a high content of alite used in the present invention may be carried out in accordance with, for example, a method for producing a highly active cement clinker described in Patent Document 2 or Patent Document 3.

  That is, HM (hydraulic modulus) and AI (activity coefficient) are applied to each raw material such as limestone, clay, silica stone, iron raw material and the like, which has been conventionally used as a main raw material of clinker, so as to have a predetermined mineral composition and a free lime amount. , SM (silicic acid ratio), IM (iron ratio), LSD (lime saturation), based on the blending design obtained using the raw material mill and blending silo based on the blending design, the obtained blended raw material is cement The clinker is obtained by firing in a firing kiln. The firing temperature is preferably from 1250 to 1600 ° C. Clinker cooling, crushing and the like after firing are the same as in the prior art.

[plaster]
The gypsum is not particularly limited as long as it is conventionally used for cement production, such as anhydrous gypsum and gypsum.

The amount of gypsum added is preferably 1.5 to 4.0% by weight in terms of SO ₃ with respect to the clinker having a high alite content. If the content is less than 1.5% by weight, fresh properties such as fluidity and coagulation properties at the initial stage of hydration are deteriorated, and there is a possibility that workability may be impaired. If it exceeds 4.0% by weight, unreacted gypsum delayed expansion may occur after the cement is hardened.

B. Fly ash Fly ash is a by-product produced when pulverized coal is burned in a thermal power plant and contains silica and alumina. It is a powder.

  It has been used as a cement admixture or fly ash cement in the past, and is specified in JIS as "JIA A 6201 fly ash for concrete" and "JIS R 5213 fly ash cement". According to the purpose of use, four types of qualities I to IV are defined.

  Fly ash used in the present invention is not particularly limited as long as it is conventionally used in cement admixtures or fly ash cement, etc., and may be selected according to the purpose of use. High quality I or relatively high quality II are preferred. The amount of fly ash incorporated into the cement is a ratio according to any one of Classes A to C of JIS standards.

[Fly ash cement composition]
The above-mentioned fly ash cement is a cement admixture such as a blast furnace slag fine powder, a limestone fine powder, a silica fume, a gypsum, an expanding component such as CSA, a shrinkage reducing agent, a setting modifier, and a pH adjuster which have been conventionally used. Such a chemical admixture can be used as a fly ash cement composition that is mixed (added) within a range that does not impair the strength and the performance possessed by fly ash.

  Among them, blast furnace slag fine powder, limestone fine powder, gypsum dihydrate, anhydrous gypsum and the like, which are conventionally used in combination with fly ash, are preferred. For example, it is a fly ash cement composition obtained by mixing blast furnace slag fine powder and / or limestone fine powder with the above fly ash cement. By mixing these, the strength of the initial age, the age of 28 days, and the long-term age after that can be increased.

  In order to improve the initial strength, a fly ash cement composition obtained by adding gypsum dihydrate or anhydrous gypsum to the fly ash cement may be used. In particular, it is effective for heat-cured products such as steam-cured products and autoclave-cured products.

  The production of the fly ash cement composition may be performed by a conventional method, and may be performed by mixing a predetermined admixture material with a pre-produced fly ash cement, or fly ash is added to the cement that becomes the base cement of the fly ash cement. And a predetermined admixture may be simultaneously mixed.

A. Fly ash cement It is used for the fly ash cement composition of the present invention as described above.

B. Blast-furnace slag fine powder Blast-furnace slag is a by-product generated when pig iron is produced in a blast furnace at an ironworks. After being taken out of the blast furnace together with pig iron in a molten state at about 1500 ° C, it is water-cooled and solidified sand-like amorphous material. Which has a latent hydraulic property that causes a hydration reaction by an alkali stimulant.

The blast furnace slag fine powder is not particularly limited as long as it has been conventionally used for a cement admixture or the like. Among them, those having a Blaine value of about 4000 to 12000 (cm ² / g) are preferable. By adding blast furnace slag fine powder, strength enhancement, salt barrier properties, effective use of blast furnace slag, reduction of environmental load, etc. can be achieved.

C. Limestone Fine Powder Limestone fine powder can be used without any problem as long as it is made of calcium carbonate and has a purity generally available. What is conventionally used for cement, a cement composition, and a cement admixture is preferable in terms of supply and economy.

Among them, the Blaine value is preferably 2000 to 10000 (cm ² / g). By adding limestone fine powder, the strength expression can be slightly increased, and the suppression of shrinkage can be further enhanced.

D. Gypsum dihydrate Gypsum gypsum is a dihydrate of calcium sulfate and has been used as a constituent material of gypsum board and cement concrete. Gypsum includes chemical gypsum such as natural gypsum and waste gypsum.

In the present invention, there is no particular limitation as long as it is conventionally used in a cement composition or a cement admixture and does not significantly impair the strength development. The fineness of the gypsum is not particularly limited, but a Blaine value of 2,000 to 10,000 (cm ² / g) is preferable.

E. FIG. Anhydrite Anhydrous gypsum includes natural anhydrite, hydrofluoric anhydrite, natural dihydrate gypsum and anhydrous gypsum produced by baking gypsum recovered from waste gypsum board or waste gypsum board. Any gypsum containing 90% or more gypsum can be used. The fineness of the anhydrous gypsum is not particularly limited, but a Blaine value of 2,000 to 10,000 (cm ² / g) is preferable.

Next, the fly ash cement used in the fly ash cement composition of the present invention and the strength performance confirmation test of the fly ash cement composition of the present invention will be described.

<< Strength performance confirmation test; Example >>
<Material used>
(1) Each Shisei cement shown in Cement Table 1 (gypsum with gypsum got out and discharge of Showa Denko KK, added uniformly 2.5% converted to SO ₃ to clinker)
(2) Fly ash • Classified fly ash of JIS standard type II so as to have a Blaine value of about 4000 (cm ² / g)
(3) Blast furnace slag fine powder (manufactured by Day Shii Co .; Brain value: 4350 cm ² / g)
(4) Limestone fine powder (manufactured by Chichibu Pacific Co .; Brain value: 4770 cm ² / g)
(5) Gypsum (Noritake Co .; Brain value 2740 cm ² / g)
(6) Anhydrite (Noritake Co .; Brain value 5860 cm ² / g)

<Fly ash cement and fly ash cement composition>
Table 1 shows the composition of the base cement, and Table 2 shows the formulations of fly ash cement and fly ash cement composition using the base cement. The clinker contains a small amount of free lime, alkali sulfate and the like in addition to the minerals described. The base cement F in Table 1 is equivalent to ordinary Portland cement.

<Strength performance confirmation test>
Prepare a mortar specimen in accordance with JIS R 5201 "Physical test method of cement"
A compression strength test was performed according to a standard compression strength test method. The test material ages were 3, 7, and 28 days. Table 3 shows the compressive strength test results of the fly ash cement, and Table 4 shows the compressive strength test results of the fly ash cement composition.

Formulation No. using base cement F or base cement G having a C ₃ S / C ₂ S of less than 7 7 and Formulation No. Sample No. 8 exhibited poor strength development, and the above-mentioned target strengths at the age of 3 days and at the age of 28 days, which were aimed at by the present invention, could not be secured.

In addition, the formulation No. using a base cement E having a C ₃ S / C ₂ S of more than 50. Sample No. 6 could secure the initial strength at the age of 3 days, but could not attain the target strength at the age of 28 days.

_{C 3} S / C ₂ S base cement A there is a range of 7 to 50 of the present invention, the base cement B, the base cement C, based cements D, each formulation of Class B corresponds with base cement H (formulation No. In the case of Nos. 2 to 5 and No. 9), the target strengths corresponding to the above-mentioned class B could be satisfied both at the age of 3 days and at the age of 28 days. In addition, compound No. In the case of No. 1, even higher strength was obtained than in the case of the above-mentioned class B, and the compound No. It was also found that a high strength that satisfies the target strength can be obtained by selecting the type of the base cement even in the case of 10.

Formulation No. using a base cement G having C ₃ S / C ₂ S of less than 7 Formulation No. 17 was not added by adding limestone fine powder. Although the strength was increased at the age of 28 days as compared with No. 8, sufficient strength could not be secured at both the age of 3 days and the age of 28 days.

Formulation No. in which anhydrous gypsum and gypsum were added using base cement B having C ₃ S / C ₂ S in the range of 7 to 50 of the present invention. 15, Formulation No. No. 16 has the same base cement but no gypsum added. The strength at 3 days of age was increased as compared with No. 3, and a higher initial strength was obtained.

_{C 3} S / C ₂ S formulation was added only blast furnace slag with a base cement B in the range of 7 to 50 of the present invention No. Even in the case of No. 11, a high strength equal to or higher than the target strength was able to be secured in both the age of 3 days and the age of 28 days.

Formulation No. in which limestone fine powder was added using base cement B having C ₃ S / C ₂ S in the range of 7 to 50 of the present invention. 12 to No. As for No. 14, a high strength equal to or higher than the above-mentioned target strength could be secured in both the material age of 3 days and the material age of 28 days.

  In particular, Formulation No. Compared with No. 3, the increase in strength up to a material age of 28 days was increased by the addition of the fine limestone powder. From this, in the present invention, it was found that the effect of adding fine limestone powder on the increase in strength up to 28 days of age with cement using a clinker containing high alite was found.

Claims (4)

As a base cement of fly ash cement as a mixed cement obtained by mixing fly ash with cement, the C ₃ S content obtained by the Borg method is 60 to 71%, the C ₂ S content is 1% or more, and C ₃ S and C in total of ₂ S is _{70~80%, C 3 S / C} 2 S content ratio has a clinker mineral composition of 7 to 50, free lime content 1.0 to 4.0 wt% of alite high Fly ash cement composition obtained by adding 2 to 10% by weight of blast furnace slag fine powder and / or limestone fine powder in total to fly ash cement using cement obtained by adding gypsum to content clinker . _2. The fly ash cement composition according to claim 1, wherein the clinker having a high alite content has a clinker mineral composition having a C ₂ S amount determined by a Borg equation of 1 to 15%. 3 . In the alite-rich clinker, C ₃ S / C ₂ S content ratio fly ash cement composition according to claim 1 or 2, characterized in that it has a clinker mineral composition of 7-20. In the clinker having a high alite content, the amount of C ₃ A obtained by the Borg equation is 8 to 12%, the amount of C ₄ AF is 7 to 10%, and the total amount of C ₃ A and C ₄ AF is 18 to 19%, C ₃ a / C ₄ AF content ratio fly ash cement composition according to claim 1, characterized in that it comprises a clinker mineral composition of 0.9 to 1.5.