JP4520005B2 - Cement admixture and cement composition - Google Patents

Description

【００２４】
表１より、本発明のセメント混和材を使用したモルタルは、比較例の実験No.1-1,1-13と比べ、優れた膨張特性を示すことが判る。
【００２５】
実施例２
実験No.1-3で使用したクリンカーを使用し、セッコウ類の種類を変えたこと以外は、実施例１と同様に行った。その結果を表２に示す。
【００２６】
＜使用材料＞
セッコウ類Ｂ：試薬１級、半水セッコウ
セッコウ類Ｃ：試薬１級、二水セッコウ
【００２７】
【表２】

【００２８】
表２より、本発明のセメント混和材を使用することにより、何れのモルタルも優れた膨張特性を示しているが、中でも無水セッコウを使用した実験No.1-3が優れていることが判る。
【００２９】
実施例３
ＣａＯ原料、Ａｌ₂Ｏ₃原料、Ｆｅ₂Ｏ₃原料及びＳｉＯ₂原料を配合し、混合粉砕した後、電気炉で１３００℃、３０分間熱処理して遊離石灰、Ｃ₁₁Ａ₇・ＣａＦ₂、Ｃ₄ＡＦ及びカルシウムシリケート（Ｃ₃Ｓ）を含有する様々な組成のクリンカーを合成した。次いで、無水セッコウと各種クリンカーをボールミルを用いて混合粉砕し、ブレーン比表面積3500±200cm²/gに粉砕して表３に示すような組成のセメント混和材を調製したこと以外は、実施例１と同様に行った。
【００３０】
＜使用材料＞
ＳｉＯ₂原料：試薬１級、二酸化ケイ素
【００３１】
【表３】

【００３２】
表３より、珪酸率が１．０未満の範囲でカルシウムシリケートを含有する本発明のセメント混和材を使用したモルタルは、優れた膨張特性を示すことが判る。
【００３３】
実施例４
工業原料であるＣａＯ原料、Ａｌ₂Ｏ₃原料、フッ素原料及びＦｅ₂Ｏ₃原料を配合し、ロータリーキルンを用いて焼点温度１３５０℃で焼成して表４に示すような化学組成のクリンカーを合成し、ボールミルを用いて、無水セッコウと共に混合粉砕してブレーン比表面積3500cm²/gのセメント混和材を調製したこと以外は、実施例１と同様に行った。
化学組成を基に算出した化合物組成を表５に示す。比較のために、市販のカルシウムサルホアルミネート系膨張材（膨張材Ａ）と石灰系膨張材（膨張材Ｂ）の結果についても併記した。長さ変化率の測定結果を表６に示す。
【００３４】
＜使用材料＞
ＣａＯ原料：新潟県青海鉱山産石灰石
Ａｌ₂Ｏ₃原料：中国産ボーキサイト
フッ素原料：中国産ホタル石
Ｆｅ₂Ｏ₃原料：圧延スケール
無水セッコウ：天然無水セッコウ
膨張材Ａ：市販のカルシウムサルホアルミネート系膨張材、ブレーン比表面積2940cm²/g
膨張材Ｂ：市販の石灰系膨張材、ブレーン比表面積3610cm²/g
【００３５】
【表４】

【００３６】
【表５】

【００３７】
【表６】

【００３８】
表６より、本発明のセメント混和材を使用したモルタルは、市販の膨張材を使用したモルタルと比べ、優れた膨張特性を示すことが判る。
【００３９】
実施例５
実施例４の実験No.4-1で使用したセメント混和材を使用し、セメント組成物１００部中のセメント混和材の使用量を変えたこと以外は、実施例３と同様に行った。その結果を表７に示す。
【００４０】
【表７】

【００４１】
表７より、本発明のセメント混和材の使用量を大きくすると、モルタルの膨張特性が向上することが判る。
【００４２】
【発明の効果】
本発明のセメント混和材を使用することにより、優れた膨張特性を有するセメント組成物が得られる。[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a cement admixture and a cement composition used in the field of civil engineering and construction.
[0002]
[Prior art]
Reduction of cracks in cement and concrete and improvement of bending strength are important from the viewpoint of reliability, durability, aesthetics, etc. of concrete structures. Cement admixtures, which are cement admixtures, have the effect of improving these. Further technical progress is desired. Conventional cement admixtures that give expansibility to cement and concrete include, for example, free lime-auin-anhydrous gypsum-based expansive material (Japanese Patent Publication No. 42-21840) and free lime-calcium silicate-anhydrous gypsum-based expansion. There were materials (Japanese Patent Publication No. 53-31170).
[0003]
[Problems to be solved by the invention]
In recent years, high-fluidity concrete and high-strength concrete have been actively developed for the purpose of improving the performance of concrete. However, it has been pointed out that these high-performance concretes do not sufficiently exert the effect of cement-based expansive materials, and the development of cement-based expansive materials with excellent expansibility that can give large expansibility even when the mixing ratio is small. Is actually waiting.
Recently, a shift from a conventional specification-based design system to a performance-based design system has been studied. It is thought that a clear performance rule will be established for durability that has been neglected until now. That is, since the influence of the crack on the durability is quantified, it is an urgent task to reduce the crack. In order to widely use cement-based expansion materials that are effective in reducing cracks, it is essential to reduce the amount of use and reduce the economic burden.
As a result of various studies to solve these problems, the present inventors have obtained the knowledge that the above problems can be solved by using a specific cement admixture, and have completed the present invention. It was.
[0004]
[Means for Solving the Problems]
That is, the present invention relates to free lime obtained by heat treatment of a CaO raw material, an Al ₂ O ₃ raw material, a halogen element raw material and an Fe ₂ O ₃ raw material, C ₁₁ A ₇ · CaX ₂ (X is a halogen element), and calcium alumino. a clinker containing ferrite, and gypsum, Ri silicate ratio Na contain calcium silicate in a range of less than 1.0, in 100 parts of cement admixture, of free lime is 40 to 60 parts, C ₁₁ a ₇ A cement admixture containing 10 to 25 parts of CaX _2, 5 to 15 parts of calcium aluminoferrite, 10 to 20 parts in total of calcium aluminoferrite and calcium silicate, and 10 to 30 parts of anhydrous gypsum of gypsum , et al is a cement and cement composition containing the said cement admixture.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0006]
The cement admixture of the present invention contains free lime, C ₁₁ A ₇ · CaX ₂ (X is a halogen element), calcium aluminoferrite and gypsum. The ratio of these compounds is not particularly limited, but usually, 30 to 60 parts of free lime is preferable in 35 parts of cement admixture, and more preferably 35 to 55 parts. C ₁₁ A ₇ · CaF ₂ is preferably 10 to 35 parts, more preferably 15 to 25 parts. The calcium aluminoferrite is preferably 5 to 20 parts, more preferably 10 to 15 parts. Furthermore, the gypsum is preferably 10 to 40 parts, more preferably 15 to 30 parts. If the composition ratio of each compound in the cement admixture is not within the above range, excellent expansion characteristics may not be obtained.
In addition,% and a part used by this invention are a mass unit.
[0007]
The C ₁₁ A ₇ · CaX _{2 of the} present invention is a CaO—Al ₂ O ₃ —X-based compound, and is a general term for compounds in which halogen elements such as fluorine and chlorine are solid-solved in C ₁₂ A _7. . C ₁₁ A ₇ · CaX ₂ includes those in which trace components such as Na ₂ O and K ₂ O are dissolved. C ₁₁ A ₇ · CaX ₂ is is also similar in crystal structure as C ₁₂ A _7, when identified by powder X-ray diffraction method, showing the same diffraction pattern as C ₁₂ A _7.
The calcium aluminoferrite of the present invention is a generic term for CaO—Al ₂ O ₃ —Fe ₂ O ₃ compounds and is not particularly limited, but in general, CaO is C, Al ₂ O _3. When A is Fe and Fe ₂ O ₃ is F, compounds such as C ₄ AF and C ₆ A ₂ F are well known. Normally, it can be considered that it exists as C ₄ AF. In the present invention, calcium aluminoferrite is hereinafter abbreviated as C ₄ AF.
[0008]
When producing the cement admixture of the present invention, the CaO raw material, the Al ₂ O ₃ raw material, the halogen element raw material, and the Fe ₂ O ₃ raw material are heat-treated to comprise free lime, C ₁₁ A ₇ · CaX ₂ and C ₄ AF. It is produced by synthesizing clinker and pulverizing it with gypsum, or by separately pulverizing and mixing. When free lime, C ₁₁ A ₇ · CaX ₂ and C ₄ AF are synthesized separately and mixed, the effects of the present invention cannot be obtained.
[0009]
Heat treatment of CaO raw material, Al ₂ O ₃ raw material, halogen element raw material and Fe ₂ O ₃ raw material to synthesize clinker consisting of free lime, C ₁₁ A ₇ · CaX ₂ and C ₄ AF and pulverize it with gypsums As a method for confirming whether or not the product is manufactured by mixing after being separately pulverized, for example, coarse particles of cement admixture, specifically, particles larger than 100 μm are observed with a microscope (SEM- It can be easily discriminated by performing composition analysis by observing with EDS) and confirming that free lime, C ₁₁ A ₇ · CaX ₂ and C ₄ AF are mixed in the particles.
[0010]
Although it is the heat processing temperature at the time of manufacturing the cement admixture of this invention, the range of 1100-1600 degreeC is preferable, and the range of 1200-1500 degreeC is more preferable. If it is less than 1100 degreeC, the expansion characteristic of the obtained cement admixture is not enough, and even if it exceeds 1600 degreeC, the improvement of the further effect cannot be expected.
[0011]
Examples of the CaO raw material include limestone and slaked lime. Examples of the Al ₂ O ₃ raw material include bauxite and aluminum residual ash. Examples of the halogen element raw material include fluorine compounds such as fluorite (calcium fluoride), calcium chloride, Examples of the Fe ₂ O ₃ raw material include rolling scale, copper calami, iron powder, steel sludge, and commercially available iron oxide.
[0012]
Impurities are present in the cement admixture of the present invention. Specific examples thereof include SiO ₂ , MgO, TiO ₂ , P ₂ O ₅ , Na ₂ O, K ₂ O, CuO, ZnO, Ag ₂ O, and the like, which do not substantially impair the object of the present invention. However, among these, SiO ₂ is preferably in a range of less than 1.0 in terms of silicic acid, and more preferably in a range of less than 0.6. When the silicic acid ratio is 1.0 or more, there are cases where excellent expansion characteristics cannot be obtained. The silicic acid ratio as used in the present invention is calculated from the following formula from the amount of SiO _{2, the} amount of Al ₂ O _{3 and the} amount of Fe ₂ O _{3 in} the clinker.
Silicic acid ratio = SiO ₂ / (Al ₂ O ₃ + Fe ₂ O ₃ )
Further, the amount of SiO ₂ in the clinker is preferably 5.0% or less, and more preferably 3.0% or less. If it exceeds 5.0%, an excellent expansion property may not be obtained.
[0013]
The gypsum referred to in the present invention includes two-water gypsum, half-water gypsum, anhydrous gypsum, etc., and is not particularly limited, but because the effect of the present invention is remarkable, anhydrous gypsum should be used. Is preferred.
[0014]
The particle size of the cement admixture of the present invention, but are not particularly limited, is preferably 1500~9000cm ² / g in Blaine specific surface area, 2500~5000cm ² / g is more preferable. If the particle size of the cement admixture is less than 1500 cm ² / g, long-term durability may deteriorate, and if it exceeds 9000 cm ² / g, sufficient expansion characteristics may not be obtained.
[0015]
Although the usage-amount of the cement admixture of this invention is not specifically limited, Usually, 5-15 parts are preferable in a cement composition which consists of cement and a cement admixture, and 7-12 parts are more preferable. . If it is less than 5 parts, sufficient expansion characteristics may not be obtained, and if it exceeds 15 parts, long-term durability may be deteriorated.
[0016]
As the cement of the present invention, various cements such as ordinary cement, early strength, very early strength, low heat and moderate heat, mixed cement obtained by mixing blast furnace slag, fly ash and silica with these cements, and limestone powder, etc. There are mixed filler cements.
[0017]
In the present invention, a water reducing agent, a high performance water reducing agent, an AE water reducing agent, a high performance AE water reducing agent, a fluidizing agent, an antifoaming agent, a thickening agent, a rust preventive agent, a defrosting agent, a shrinkage reducing agent, a polymer emulsion and a coagulation It is possible to use one or two or more of modifiers, cement rapid hardening materials, clay minerals such as bentonite, and anion exchangers such as hydrotalcite, etc., as long as the object of the present invention is not substantially inhibited. Is possible.
[0018]
In this invention, the mixing method of each material is not specifically limited, Each material may be mixed at the time of construction, and the part or all may be mixed beforehand. Any existing apparatus can be used as the mixing apparatus, and examples thereof include a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a nauter mixer.
[0019]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
[0020]
Example 1
After mixing CaO raw material, Al ₂ O ₃ raw material, fluorine raw material and Fe ₂ O ₃ raw material, mixing and pulverizing, heat treatment at 1300 ° C. for 30 minutes in an electric furnace, free lime, C ₁₁ A ₇ · CaF ₂ , and C ₄ Various compositions of clinker containing AF were synthesized. Next, anhydrous gypsum and various clinker were mixed and pulverized using a ball mill, and pulverized to a Blaine specific surface area of 3500 ± 200 cm ² / g to prepare a cement admixture having the composition shown in Table 1.
When the clinker was identified by powder X-ray diffraction, it contained free lime, C ₁₁ A ₇ · CaF ₂ and C ₄ AF. The compound composition of the cement admixture was calculated by calculation based on the chemical composition. The chemical composition was determined according to JIS R 5202.
Using 100 parts of cement and cement composition consisting of cement, 9 parts of cement admixture were used to prepare a mortar with a water / cement composition ratio = 50% and a cement composition / sand ratio = 1/3, The expansion coefficient was measured. For comparison, free lime, C ₃ A and C ₄ AF were separately synthesized and pulverized, and the same was applied to the cement admixture compounded so as to have the same compound composition as Experiment No. 1-3. The experiment was conducted. The results are shown in Table 1.
[0021]
<Materials used>
CaO raw material: reagent grade 1, calcium carbonate Al ₂ O ₃ raw material: reagent grade 1, aluminum oxide fluorine raw material: reagent grade 1, calcium fluoride Fe ₂ O ₃ raw material: reagent grade 1, ferric oxide gypsum A: reagent First grade, anhydrous gypsum free lime: synthesized by heat-treating CaO raw material at 1300 ° C for 30 minutes.
C ₁₁ A ₇ · CaF ₂ : synthesized by heat-treating at 1300 ° C. for 30 minutes after mixing and pulverizing raw materials blended at a ratio of 11 mol of CaO raw material, 7 mol of Al ₂ O ₃ raw material and 1 mol of fluorine raw material.
C ₄ AF: raw material blended at a ratio of 4 moles of CaO raw material, 1 mole of Al ₂ O ₃ raw material and 1 mole of Fe ₂ O ₃ raw material, mixed and pulverized, and then heat-treated at 1300 ° C. for 30 minutes twice to synthesize .
Sand: JIS standard sand (ISO679 compliant)
[0022]
<Measurement method>
Length change rate: Measured at a material age of 7 days according to JIS A 6202.
[0023]
[Table 1]

[0024]
From Table 1, it can be seen that the mortar using the cement admixture of the present invention exhibits excellent expansion characteristics as compared with Experiments No. 1-1 and 1-13 of the comparative examples.
[0025]
Example 2
The same procedure as in Example 1 was performed except that the clinker used in Experiment No. 1-3 was used and the kind of gypsum was changed. The results are shown in Table 2.
[0026]
<Materials used>
Gypsum B: Reagent grade 1, semi-water gypsum C: Reagent grade 1, two-water gypsum
[Table 2]

[0028]
From Table 2, it can be seen that by using the cement admixture of the present invention, any mortar exhibits excellent expansion characteristics, but among them, Experiment No. 1-3 using anhydrous gypsum is excellent.
[0029]
Example 3
After mixing CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and SiO ₂ raw material, mixing and pulverizing, heat treatment at 1300 ° C. for 30 minutes in an electric furnace, free lime, C ₁₁ A ₇ · CaF ₂ , C Various compositions of clinker containing ₄ AF and calcium silicate (C ₃ S) were synthesized. Next, Example 1 except that anhydrous gypsum and various clinker were mixed and pulverized using a ball mill and pulverized to a Blaine specific surface area of 3500 ± 200 cm ² / g to prepare a cement admixture having the composition shown in Table 3. As well as.
[0030]
<Materials used>
SiO ₂ raw material: reagent grade 1, silicon dioxide
[Table 3]

[0032]
From Table 3, it can be seen that the mortar using the cement admixture of the present invention containing calcium silicate with a silicic acid ratio of less than 1.0 exhibits excellent expansion characteristics.
[0033]
Example 4
Combining industrial raw materials such as CaO raw material, Al ₂ O ₃ raw material, fluorine raw material and Fe ₂ O ₃ raw material, using a rotary kiln, firing at a baking temperature of 1350 ° C. to synthesize clinker with chemical composition as shown in Table 4 Then, the same procedure as in Example 1 was carried out except that a cement admixture having a brain specific surface area of 3500 cm ² / g was prepared by mixing and grinding with anhydrous gypsum using a ball mill.
Table 5 shows the compound composition calculated based on the chemical composition. For comparison, the results of commercially available calcium sulfoaluminate-based expansion material (expansion material A) and lime-based expansion material (expansion material B) are also shown. Table 6 shows the measurement results of the rate of change in length.
[0034]
<Materials used>
CaO raw material: Limestone Al ₂ O ₃ raw material from Aomi mine, Niigata Prefecture: Chinese bauxite fluorine raw material: Chinese fluorite Fe ₂ O ₃ raw material: Rolled scale anhydrous gypsum: Natural anhydrous gypsum expanded material A: Commercial calcium sulfoaluminate series Intumescent material, Blaine specific surface area 2940cm ² / g
Expansion material B: Commercially available lime-based expansion material, Blaine specific surface area 3610 cm ² / g
[0035]
[Table 4]

[0036]
[Table 5]

[0037]
[Table 6]

[0038]
From Table 6, it can be seen that the mortar using the cement admixture of the present invention exhibits excellent expansion characteristics as compared with the mortar using a commercially available expansion material.
[0039]
Example 5
The same operation as in Example 3 was performed except that the cement admixture used in Experiment No. 4-1 of Example 4 was used and the amount of the cement admixture used in 100 parts of the cement composition was changed. The results are shown in Table 7.
[0040]
[Table 7]

[0041]
From Table 7, it can be seen that when the amount of the cement admixture of the present invention is increased, the expansion characteristics of the mortar are improved.
[0042]
【The invention's effect】
By using the cement admixture of the present invention, a cement composition having excellent expansion characteristics can be obtained.

Claims (2)

A clinker containing CaO raw material, Al ₂ O ₃ raw material, halogen element raw material and free lime obtained by heat treatment of Fe ₂ O ₃ raw material, C ₁₁ A ₇ · CaX ₂ (X is a halogen element), and calcium aluminoferrite , and gypsum, Ri silicate ratio Na contain calcium silicate in a range of less than 1.0, a cement admixture in 100 parts of free lime is 40 to 60 parts, the C ₁₁ a ₇ · CaX ₂ 10~ A cement admixture comprising 25 parts, 5 to 15 parts of calcium aluminoferrite, 10 to 20 parts in total of calcium aluminoferrite and calcium silicate, and 10 to 30 parts of anhydrous gypsum . A cement composition comprising cement and the cement admixture according to claim 1 .