JP2008156231A - Cement composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement composition in which chlorine bypass dust is utilized effectively and which is excellent in long-term strength and fluidity. <P>SOLUTION: The cement composition is manufactured by mixing a cement clinker produced in a cement plant having a chlorine bypass unit, the chlorine bypass dust recovered by collecting the dust existing in the bled kiln exhaust gas, gypsum and limestone. The chlorine bypass dust contains chlorine, and the cement composition satisfies 0<Y<(-54X+4.5) (wherein Y (mass%) is the amount of the limestone; X (mass%) is the amount of chloride ions). The total of the amount of C<SB>3</SB>A and that of C<SB>4</SB>AF in the cement clinker is 18-23 mass% and the mass ratio of the amount of C<SB>3</SB>S to that of C<SB>2</SB>S is 2.0-5.0. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cement composition that effectively uses chlorine bypass dust recovered in a cement manufacturing plant equipped with a chlorine bypass device.

  Conventionally, various methods of using chlorine bypass dust collected in a cement production plant equipped with a chlorine bypass device for cement compositions have been studied.

  For example, like the cement raw material firing device shown in Patent Document 1, after extracting a part of the exhaust gas in the cement kiln with a chlorine bypass device, volatile components such as alkali chloride contained in the exhaust gas are fixed outside the system. There is a technique for reducing the amount of alkali chloride and the like in the cement raw material firing system by performing a chemical treatment. This chlorine bypass device is additionally installed in the cement kiln for the purpose of preventing coating troubles in the cement raw material firing system and extracting chlorine and the like in the cement clinker.

  The gas components extracted by the chlorine bypass device are returned to the cement raw material system again through the dust collector or released into the atmosphere. However, chlorides such as KCl that have undergone a thermal history of 1000 ° C. or more at the kiln bottom Solid materials composed of calcined cement raw materials and sulfates thereof are generated. This solid matter is called chlorine bypass dust, and may be made into sludge or the like having a reduced chlorine concentration by washing with water.

  Patent Document 2 discloses a cement composition comprising 90 to 99.7% by mass of cement containing blast furnace slag or fly ash and 0.3 to 10% by mass of chlorine bypass dust and a method for producing the same. According to this production method, by adding chlorine bypass dust, there is an effect of increasing the initial strength of 3 days and 7 days of age, and there is no decrease in the strength of 28 days of age, which is a defect of the initial strength improver. It has been shown. Further, the amount of chlorine bypass dust added here is 0.3 to 10% by mass, and if less than 0.3% by mass, there is no effect of increasing the initial strength of cement containing blast furnace slag or fly ash. It is indicated that when the amount is more than mass%, the amount of salt increases and the use as concrete is limited.

  Patent Document 3 discloses a cement composition in which chlorine bypass dust and limestone are added to cement. In this document, when a cement dispersant such as polycarboxylic acid is added to a cement composition to impart fluidity, sulfuric acid supplied by gypsum or cement dispersant is added by adding an appropriate amount of limestone and chlorine bypass dust. It describes that fluidity deterioration due to ion inhibition is prevented.

Japanese Patent Laid-Open No. 10-330136 JP-A-10-218657 JP, 2000-281417, A On the other hand, in recent cement manufacture, from the viewpoint of effective use of waste, cases where a large amount of waste containing a large amount of Al, such as coal ash and construction generated soil, is increasing. In the chemical composition design of clinker and cement, the amount of Al is increased, and as a result, the total amount of the interstitial phase, that is, the total amount of C3A and C4AF is increased in the clinker mineral design, and accordingly, the amount of C3S and C2S is increased. , The long-term strength after 28 days of age tended to be difficult.

  Although the composition of chlorine bypass dust differs depending on the characteristics of the kiln, the above document does not mention anything about the influence of the composition of the chlorine bypass dust on the cement composition. Moreover, it does not disclose an effective utilization technique of chlorine bypass dust to cement containing a large amount of interstitial phase.

  Therefore, the present invention has found a suitable condition that long-term strength and fluidity do not deteriorate in a cement composition containing gypsum and chlorine bypass dust, targeting Portland cement clinker with a large amount of interstitial pores. The object was to provide an excellent cement composition.

  The present inventors have intensively studied the influence of the addition of chlorine bypass dust to the Portland cement clinker containing a large amount of interstitial amounts on strength development with various chlorine bypass dusts and various addition amounts. Is effective, and the amount of chlorine bypass dust added is limited by the amount of chloride ions contained in the dust, and due to the fluidity or strength development of mortar and concrete, there is an appropriate range between the amount of limestone and the amount of chloride. The present invention has been found and the present invention has been completed.

That is, the cement composition according to the present invention includes cement clinker, gypsum, limestone, and chlorine bypass dust as composition components, and the relationship between the limestone amount Y mass% and the chloride ion amount X mass% is 0 <Y. <−54X + 4.5 is satisfied, and the total amount of the C ₃ A amount and the C ₄ AF amount of the clinker is 18 to 23% by mass, and the mass ratio of the C ₃ S amount and the C ₂ S amount is 2.0 to 5.0.

  The cement composition according to the present invention exhibits superior initial strength and long-term strength when cured, as compared with a case where a cement composition of Y ≧ −54X + 4.5 is cured. Moreover, the cement composition according to the present invention has sufficient fluidity with an appropriate slump flow than the cement composition of Y = 0. Thereby, the cement composition with stable quality can be manufactured by effectively using the chlorine bypass dust.

  Furthermore, the cement composition preferably contains 1% by mass to 5% by mass of blast furnace slag. Thereby, it can be set as the cement composition which utilized the latent hydraulic property of blast furnace slag moderately.

Also, the Blaine specific surface area of the cement composition is preferably 2500cm ² / g~4000cm ² / g. If the Blaine specific surface area is in this range, sufficient initial strength and long-term strength can be expressed in the cement composition.

  According to the present invention, chlorine bypass dust can be effectively used, and the long-term strength and fluidity are excellent.

  Hereinafter, preferred embodiments of a cement composition according to the present invention will be described in detail with reference to the drawings.

The cement composition includes Portland cement clinker, gypsum, limestone, and chlorine bypass dust. Portland cement clinker has a precondition that the amount of interstitial phase (C ₃ A and C ₄ AF) is 18 to 23% by mass. In this case, it manufactures using the cement manufacturing plant provided with the chlorine bypass device which extracts some exhaust gas in a kiln. Chlorine bypass dust is dust collected from the exhaust gas extracted by the chlorine bypass device, and is usually solid, but may be sludge or the like having a reduced chlorine concentration obtained by washing with water. The solid substance of this chlorine bypass dust consists of chlorides such as KCl, NaCl, CaCl ₂ , calcined cement raw materials, sulfates thereof, and the like. Chlorine bypass dust having a chloride ion content (γ) of 1 to 40% by mass can be used.

  In producing a cement composition using a cement production plant equipped with such a chlorine bypass device, the amount of limestone Y mass% with respect to the amount of chloride ions X mass% derived from chlorine bypass dust is expressed by the following formula (1 ) To satisfy the relationship.

0 <Y <−54X + 4.5 (1)
The allowable limit (upper limit) of the amount of chloride ions in the cement composition derived from chlorine bypass dust is preferable because the effective use amount of chlorine bypass dust increases, but on the other hand, Since the influence becomes large, generally it is preferably within 0.07% by mass, and more preferably limited to 0.05% by mass.

  The chloride ion content X mass% in the composition is calculated from the chloride ion content γ mass% in chlorine bypass dust and the addition amount δ mass% of chlorine bypass dust as X = γ × δ ÷ 100. . Of course, X> 0. The amount of chloride ions is a value measured according to JIS R 5202: 1999 “Chemical analysis method of Portland cement”. The chemical component excluding the chloride ion content of the chlorine bypass dust is measured according to JIS M 8853: 1998 “Chemical analysis method of aluminosilicate raw material for ceramics”.

  The inclusion of limestone in the cement composition of the present invention is one of the essential requirements, but the appropriate amount is determined in relation to the chloride ion amount X mass%. The compressive strength of the hardened mortar or concrete produced by the cement composition satisfying this condition is sufficiently secured. Moreover, the fluidity of mortar and concrete is good. When Y exceeds -54X + 4.5, the compressive strength property of a cement composition will fall. Also, if the limestone amount Y mass% is 0 (no additive), the fluidity of mortar and concrete will be hindered by the decrease in performance of cement dispersant due to the addition of chlorine bypass dust and the interaction with sulfate ions derived from gypsum. It is not preferable. The allowable upper limit (% by mass) of the amount of limestone (Y) is uniquely determined by the amount of chloride brought from the chlorine bypass dust, but is 0.5% by mass or more.

  The effect of limestone in the cement composition promotes the development of initial strength due to chlorine bypass dust, but when the amount of added chlorine bypass dust is excessive, water is added to the cement composition and mixed. At a short time after completion, it may temporarily stiffen or cause pseudo-condensation in which it loses its fluidity, resulting in a decrease in strength and a possibility of causing rusting of the reinforcing bars. Note that potassium chloride contained in the chlorine bypass dust has an action of increasing the initial strength of the cement.

  The cement clinker used in the cement composition is not particularly limited, and those for JIS R 5210: 2003 “Portland cement” can be used.

  Cement compositions are obtained by grinding with gypsum, limestone and chlorine bypass dust using these clinker.

  The types of gypsum used in the production of the cement composition include natural gypsum, drainage gypsum, hydrofluoric acid gypsum, phosphate gypsum, etc., and these gypsum forms are dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum. It may be.

The limestone used for producing the cement composition preferably contains 53% or more of CaCO _{3 in} terms of CaO. The CaO equivalent is a value measured according to JIS M 8850: 1994 “Limestone analysis method”.

When blast furnace slag powder is added to the cement composition, the blast furnace slag powder is rapidly crushed and is preferably contained in the cement composition in an amount of 1% by mass to 5% by mass. Thereby, it can be set as the cement composition which utilized the latent hydraulic property of blast furnace slag moderately. The basicity of the blast furnace slag is 1.4 or more, preferably 1.7 or more. Here, the basicity is calculated by dividing the total amount of CaO, MgO and Al ₂ O ₃ by the amount of SiO ₂ . These contents are measured according to JIS R 5202: 1999 “Chemical analysis method of Portland cement”.

Cement composition, Blaine specific surface area is preferably 2500cm ² / g~4000cm ² / g. If the Blaine specific surface area is in this range, sufficient initial strength and long-term strength can be expressed in the cement composition. In consideration of fluidity and economy, the Blaine specific surface area of the cement composition, more preferably 3000cm ² / g~3500cm ² / g.
In addition, the cement composition of the present invention includes a blast furnace cement (with a blast furnace slag content of 70 mass% or less), a fly ash cement (with a fly ash content of 30 mass% or less), or a cement-based solidified material (SO ₃ 5 to 20 mass%). It can also be suitably used as a base cement. In the case of adding fly ash, it is preferable to use type I, type II, type III, or type IV fly ash as defined in JIS A 6201: 1999 “Fly Ash for Concrete”.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

The materials used are shown below.
(1) Cement The cement used was limestone and blast furnace as well as Portland cement clinker experimentally fired in an actual kiln with gypsum added so that the SO ₃ content of the cement would be 2.0 ± 1.0%. It was produced by adding slag and grinding with a finishing grinding mill. Table 1 shows the production conditions of the cement used. As shown in Table 1, nine types of cements (1) to (9) were produced. In addition, the limestone and blast furnace slag in the table are the content of the produced cement.

ここで、ポルトランドセメントクリンカーは、Ａ、Ｂ、Ｃの３種類を使用した。各ポルトランドセメントクリンカーＡ、Ｂ、Ｃの鉱物組成を表２に示す。なお、これらポルトランドセメントクリンカー中の塩化物イオン量は、いずれも０．００５５〜０．０２２４質量％である。また、セメント組成物はブレーン比表面積が３１００〜３４００cm²/gになるように製造した。

Here, three types of A, B, and C were used as the Portland cement clinker. Table 2 shows the mineral composition of each Portland cement clinker A, B, C. In addition, the chloride ion amount in these Portland cement clinker is 0.0055-0.0224 mass% in any case. The cement composition was produced so that the specific surface area of Blaine was 3100-3400 cm ² / g.

The mineral composition of the Portland cement clinker was determined by quantifying chemical components according to JIS R 5202: 1999 “Chemical analysis method of Portland cement”, C ₃ S content, C ₂ S content, C ₃ A content, C ₄ AF. The amount was determined by the following formulas (2) to (5).
C ₃ S content = 4.071 x CaO content-7.600 x SiO ₂ content-6.718 x Al ₂ O ₃ content-1.430 x Fe ₂ O ₃ content-2.852 x SO ₃ content (2)
C ₂ S amount = 2.876 × SiO ₂ amount−0.7544 × C ₃ S amount (3)
C ₃ A content = 2.650 x Al ₂ O ₃ content-1.682 x Fe ₂ O ₃ content (4)
C ₄ AF amount = 3.043 x Fe ₂ O ₃ (5)

The chemical composition of gypsum conforms to JIS R 9101: 1995 “Analytical method of gypsum”, the chemical composition of limestone conforms to JIS M 8850: 1994 “Analytical method of limestone”, and the chemical composition of blast furnace slag conforms to JIS R 5202: 1999. Measured according to “Chemical analysis method of Portland cement”.

  Next, Table 3 shows chemical components of gypsum, limestone and blast furnace slag added to the Portland cement clinker.

（２）塩素バイパスダスト
セメント組成物に添加する塩素バイパスダストは塩化物イオン量の異なるａ，ｂの２種類を用いた。各塩素バイパスダストａ，ｂの化学成分を表４及び表５に示す。なお、塩化物イオン量はＪＩＳ Ｒ ５２０２：１９９９「ポルトランドセメントの化学分析方法」に準じて測定した。また、塩素バイパスダストの塩化物イオン含有量を除く化学成分はＪＩＳ Ｍ ８８５３：１９９８「セラミックス用アルミノけい酸塩質原料の化学分析方法」に準じて測定した。

(2) Chlorine Bypass Dust Two types of a and b having different chloride ion amounts were used as the chlorine bypass dust added to the cement composition. Tables 4 and 5 show chemical components of the chlorine bypass dusts a and b. The amount of chloride ions was measured according to JIS R 5202: 1999 “Chemical analysis method of Portland cement”. The chemical components excluding the chloride ion content of the chlorine bypass dust were measured according to JIS M 8853: 1998 “Analytical method for aluminosilicate raw materials for ceramics”.

[Sample preparation]
Chlorine bypass dust and blast furnace slag powder were further added to the cement compositions (1) to (9) to prepare a plurality of samples (Sample Nos. 1 to 19). Table 6 shows the amount of each composition and the Blaine specific surface area in each sample.

  As shown in Table 6, those based on cement (1) have a chloride ion content of 0, 0.006, 0.021 which is additionally contained in the cement composition by chlorine bypass dust a. The chlorine bypass dust a was added to the cement in proportions of 0, 0.17, 0.61, and 1.05% by mass, respectively, and mixed to obtain a sample (Sample No. 1). 1-4).

  Those based on cement (2) have a chloride ion content of 0.010, 0.024, 0.041, 0.062 mass which is additionally contained in the cement composition by chlorine bypass dust a. %, Chlorine bypass dust a was added at a ratio of 0.29, 0.70, 1.19, and 1.80 mass%, respectively, and mixed to prepare a sample (Sample Nos. 5 to 8).

  The cement (3) -based material added with 1.19% by mass of chlorine bypass dust a had a chloride ion content of 0.041% added to the cement composition. % (Sample No. 9). In the cement (4) -based one, 0.70% by mass of chlorine bypass dust a was added to make the amount of additional chloride ions 0.024% by mass (Sample No. 10). In the cement (5), 1.19 and 1.80 mass% of chlorine bypass dust a was added to make the amount of additional chloride ions 0.041 and 0.062 mass%, respectively (Sample No. 11). , 12). In the cement (6), by adding 0.00, 0.07, and 0.18 mass% of chlorine bypass dust b, the amount of additional chloride ions is 0.000, 0.024, and 0.062 mass, respectively. % (Sample Nos. 13, 14, and 15). In cement (7), 0.07 and 0.18% by mass of chlorine bypass dust b was added to make the amount of additional chloride ions 0.024 and 0.062% by mass, respectively (Sample No. 16). , 17). In the cement (8), 0.001 and 0.18% by mass of chlorine bypass dust b was added to make the amount of additional chloride ions 0.000 and 0.062% by mass, respectively (Sample No. 18). 19). In (9), by adding 0.18% by mass of chlorine bypass dust b, the amount of additional chloride ions was 0.062% by mass (sample No. 20).

[Mortar compressive strength test and its evaluation]
Next, in accordance with “Cement physical test method” defined in JIS R 5201: 1997, a specimen was prepared from each sample, and a mortar compressive strength test was performed. The results are shown in Table 7.
In the column of “Mortar compressive strength” in Table 7, the value of the compressive strength of the specimen is shown. Further, in the column of “Mortar compressive strength change ratio”, when the compressive strength of the specimen as a reference (a product without chlorine bypass dust, sample No. 1, No. 13, No. 18) is set to 100 The ratio of the compressive strength of each specimen is shown.

That is, for specimens prepared with a cement composition using Portland cement clinker A, the specimen prepared with cement (1) -1 was used as a reference, and the mortar compressive strength relative to the mortar compressive strength of the reference specimen was determined. The change ratio (percentage) is shown.
For specimens made with a cement composition using Portland cement clinker B, the change in the mortar compressive strength relative to the mortar compressive strength of the reference specimen was taken as a reference based on the specimen made with cement (6) -1. The ratio (percentage) is shown.
For specimens made with a cement composition using Portland cement clinker C, the change in the mortar compressive strength relative to the mortar compressive strength of the reference specimen was taken as a reference based on the specimen made with cement (8) -1. The ratio (percentage) is shown.
And, the case where the mortar compressive strength change ratio at the age of 28 is 100% or more is good (◯), and the case where the mortar compressive strength change ratio at the age of 28 is less than 100% is poor (×) Judged.

FIG. 2 shows the relationship between the chloride ion amount, the limestone addition amount, and the determination result in Table 7. As shown in FIG. 2, in a cement composition using a clinker having a large amount of C ₃ A and C ₄ AF of 18 to 23% by mass, limestone addition amount Y% by mass and chlorine bypass dust If the relationship with the amount of chloride ions X mass% to be contained in the composition is a region satisfying 0 ≦ Y <−54X + 4.5 (Examples 1 to 5), the material age is 3 days, It was found that the mortar compressive strength change ratio was 100% or more even after 7 and 28 days.

[Slump flow test of concrete and its evaluation]
Next, a concrete slump flow test will be described. Each sample No. Add a fine aggregate, coarse aggregate, dispersant and water to 1-19, and use a 50 L pan-type forced kneader mixer with water cement ratio (W / C), slump flow and air volume shown in Table 8 And concrete was prepared. The amount of kneading was 30 L per batch. The following materials were used. The slump flow was measured according to JIS A 1150: 2001 “Concrete slump flow test method”.

(1) Aggregate (i) Fine aggregate (S):
Sea sand: density 2.59 g / cm ³ , coarse grain ratio 2.71, Wakamatsu (ii) coarse aggregate (G), Kitakyushu City:
-Crushed stone (2005): density 2.58 g / cm ³ , coarse particle ratio 6.58, produced in Miyano, Yamaguchi (2) kneaded water (W): tap water (3) dispersant: polycarboxylic acid-based dispersant ( (Product name: Leo Build SP8S, manufactured by NMB)
The “concrete slump flow test method” is the same as that of each sample No. 1 in the slump cone of the truncated cone cup defined in JIS A 1101: 2005 “concrete slump test method”. In this test, the concrete adjusted in 1 to 19 is packed and placed on a flat plate, the slump cone is pulled up in the vertical direction, the concrete is released from the slump cone, and the diameter of the concrete spread on the flat plate is measured. Table 8 shows the blending conditions.

  The test results are shown in Table 9. In addition, in the slump flow evaluation of concrete, the one with a slump flow within the target 60 ± 2.5 cm range and appropriate fluidity is good (◯), and the one with practically inferiority outside this range is bad ( X).

  From the results in Table 9, Sample No. in which limestone was not added to the cement composition. 16 and 17 (use cement type (7): reference table 1) was below the target slump flow value and sufficient slump flow was not obtained, but sample No. 1 in which other limestone was added to the cement composition was obtained. 1 to 15, 18, and 19 were within the target slump flow range, and a sufficient slump flow was obtained.

[Comprehensive evaluation of compressive strength test and slump flow test]
When the mortar compressive strength test and the slump flow test are comprehensively evaluated, the total amount of the C ₃ A amount and the C ₄ AF amount is 18 to 23% by mass, and the mass ratio of the C ₃ S amount and the C ₂ S amount. In the cement composition using a clinker of 2.0 to 5.0, sufficient compressive strength was obtained even in the mortar compressive strength test, and sufficient fluidity was obtained in the slump flow test. The relationship between the limestone content Y mass% and the chloride ion content X mass% in the product was 0 ≦ Y <−54X + 4.5, and limestone was added. Therefore, it was found that a cement composition satisfying 0 <Y <−54X + 4.5 is appropriate from the viewpoint of initial strength, long-term strength and fluidity.

It is a graph which shows the relationship between the determination result of a chloride ion amount, limestone addition amount, and a mortar compressive strength test.

Claims (7)

A cement clinker having a total amount of C ₃ A and C ₄ AF of 18 to 23% by mass, and a mass ratio of C ₃ S and C ₂ S of 2.0 to 5.0, gypsum, limestone, A cement composition obtained by mixing and grinding chlorine bypass dust,
A cement composition characterized in that the relationship between the limestone content Y mass% and the chloride ion content X mass% in the cement composition satisfies 0 <Y <−54X + 4.5. A cement clinker having a total amount of C ₃ A and C ₄ AF of 18 to 23% by mass, and a mass ratio of C ₃ S and C ₂ S of 2.0 to 5.0, gypsum, and limestone A cement composition to which chlorine bypass dust is added after mixing and grinding,
A cement composition characterized in that the relationship between the limestone content Y mass% and the chloride ion content X mass% in the cement composition satisfies 0 <Y <−54X + 4.5.   Furthermore, the cement composition of Claim 1 or 2 containing 1 mass%-5 mass% of blast furnace slag. Blaine specific surface area of 2500cm ² / g~4000cm ² / g any one cement composition according to claim 1, wherein it is.   A concrete composition comprising the cement composition according to any one of claims 1 to 4, a coarse aggregate, a fine aggregate, and a dispersant. A cement clinker in which the total amount of the C ₃ A amount and the C ₄ AF amount is 18 to 23% by mass, and the mass ratio of the C ₃ S amount and the C ₂ S amount is 2.0 to 5.0, gypsum, A method for producing a cement composition comprising limestone and chlorine bypass dust, wherein the relationship between the limestone content Y mass% and the chloride ion content X mass% satisfies 0 <Y <−54X + 4.5. ,
A method for producing a cement composition, comprising mixing and grinding cement clinker, gypsum, limestone, and chlorine bypass dust. A cement clinker in which the total amount of the C ₃ A amount and the C ₄ AF amount is 18 to 23% by mass, and the mass ratio of the C ₃ S amount and the C ₂ S amount is 2.0 to 5.0, gypsum, A method for producing a cement composition comprising limestone and chlorine bypass dust, wherein the relationship between the limestone content Y mass% and the chloride ion content X mass% satisfies 0 <Y <−54X + 4.5. ,
A method for producing a cement composition, comprising mixing and pulverizing cement clinker, gypsum, and limestone, and then adding chlorine bypass dust.

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