JP4459380B2 - Cement admixture and cement composition - Google Patents

Description

【００２５】
表１より、本発明のセメント混和材及びセメント組成物は、コンクリートに優れた膨張性能や流動性の保持性能を付与し、しかもポップアウト現象を防止していることが分かる。
【００２６】
実施例２
工業原料であるＣａＯ原料、Ａｌ₂Ｏ₃原料、Ｆｅ₂Ｏ₃原料及びＣａＳＯ₄原料を配合し、ロータリーキルンを用いて１４００℃で熱処理することで、表２に示す組成の膨張材を製造したこと以外は、実施例１と同様に行った。表３に化学組成から算出した化合物組成、表４に測定結果を示す。なお、比較のために市販の２種類の膨張材についても同様の実験を行った。
【００２７】
＜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−キサイト
Ｆｅ₂Ｏ₃原料：工業用酸化鉄
ＣａＳＯ₄原料：タイ産天然無水セッコウ
市販膨張材Ａ：カルシウムサルホアルミネ−ト系膨張材
市販膨張材Ｂ：石灰系膨張材
【００２８】
【表２】

【００２９】
【表３】

【００３０】
【表４】

【００３１】
表４より、本発明のセメント混和材及びセメント組成物は、コンクリートに優れた膨張性能や流動性の保持性能を付与し、しかもポップアウト現象を防止していることが分かる。
【００３２】
実施例３
実施例２の本発明の膨張材を使用し、表５に示すシリカ質微粉末の種類と量を変えてセメント混和材としたこと以外は、実施例２と同様に行った。なお、防水性試験も併せて実施した。結果を表５に併記する。
【００３３】
＜使用材料＞
シリカ質微粉末▲１▼：市販の高炉スラグをブレ−ン比表面積５０００ｃｍ²／ｇに粉砕したもの。
シリカ質微粉末▲２▼：市販のシリカフュ−ム、ブレ−ン比表面積２０００００ｃｍ²／ｇ。
シリカ質微粉末▲３▼：市販のフライアッシュをブレ−ン比表面積５０００ｃｍ²／ｇに粉砕したもの。
シリカ質微粉末▲４▼：市販のケイソウ土をブレ−ン比表面積５０００ｃｍ²／ｇに粉砕したもの。
シリカ質微粉末▲５▼：シリカ質微粉末▲１▼とシリカ質微粉末▲２▼の等量混合物、ブレ−ン比表面積１０２５００ｃｍ²／ｇ。
シリカ質微粉末▲６▼：シリカ質微粉末▲２▼と石灰石微粉末の等量混合物、ブレ−ン比表面積１０２５００ｃｍ²／ｇ。
【００３４】
＜測定方法＞
防水性試験：φ１５×３０ｃｍ、中心孔の直径２．０ｃｍの円空供試体を作成し、材齢１日で脱型後、材齢7日までの６日間水中養生を施した後、透水性試験を実施した。試験方法はアウトプット方式とし、試験体外側から水圧１０ｋｇ／ｃｍ²を４８時間加え、中心孔から出る水量を測定し、セメント混和材を配合していないコンクリ−トの透水量を１００とした時の相対値を透水比として表した。
【００３５】
【表５】

【００３６】
表５より、本発明のセメント混和材及びセメント組成物は、コンクリートに優れた膨張性能を付与すると共に、ポップアウト現象を防止し、防水性を高めることが分かる。
【００３７】
実施例４
実施例２の本発明の膨張材を７５部、シリカ質微粉末▲２▼を２５部の割合で混合したセメント混和材を使用し、セメント組成物中のセメント混和材の配合量を表６に示すように変えたこと以外は、実施例２と同様に行った。また、材齢２８日の圧縮強度を測定した。結果を表６に併記する。
【００３８】
＜測定方法＞
圧縮強度：JIS A 1108に準じて測定。
【００３９】
【表６】

【００４０】
表６より、本発明のセメント混和材は、その配合量が増加するにつれて、コンクリートの長さ変化率が大きくなる優れた膨張性能を付与すると共に、ポップアウト現象を防止し、防水性を高めることが分かる。
【００４１】
【発明の効果】
本発明のセメント混和材は配合量が少なくても、コンクリートに優れた膨張性能及び流動性の保持性能を付与し、且つ、ポップアウト現象の防止及び防水性の向上が可能である。[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]
Cement is an excellent material that is inexpensive and capable of forming large concrete structures in any shape. Moreover, it is possible to improve the strength and durability of the structure by using various cement admixtures in combination with cement. Many cement admixtures have been proposed so far, but from the viewpoints of reliability, durability, aesthetics, etc. of concrete structures, further development of cement admixtures that impart expansibility is desired. . Concrete - The cement admixture that imparts the inflatable Doo structures, for example, free lime - Auin - anhydrous gypsum-based expansive (Sho 42 - 21840 JP) and free lime - calcium silicate are - DOO - anhydrous gypsum it is - (31170 JP Sho 53), etc. system expansion material.
[0003]
[Problems to be solved by the invention]
However, when the cement admixture is unpacked into the mixer of a green plant, the cement admixture may not be uniformly dispersed in the concrete and may be agglomerated unless it is sufficiently kneaded. This may cause a so-called pop-out phenomenon that causes abnormal expansion. As a method of preventing the pop-out phenomenon, inactive inorganic powder or the like is mixed in advance in the expansion material, and even if the cement admixture is not sufficiently kneaded, the expansion material components do not aggregate and become a lump. In order to satisfy the required performance, the amount of the cement admixture must be blended so that a certain degree of dispersion can be expected, but the expansion component is diluted by mixing inert inorganic powder. The problem arises that must be increased. There is also a need for a cement admixture that provides waterproofing to the concrete. In the present invention, concrete is a general term for cement paste, mortar, and concrete.
Therefore, as a result of various studies in view of such a situation, the present inventors have found a cement admixture that can solve the above-mentioned problems by blending a specific expansion material with fine siliceous powder and / or fine limestone powder. Obtaining knowledge that it can be obtained, the present invention has been completed.
[0004]
[Means for Solving the Problems]
That is, the present invention is manufactured by heat treating CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and CaSO ₄ raw material to synthesize a clinker made of free lime, calcium aluminoferrite, calcium ferrite and anhydrous gypsum. A cement admixture containing the expanded material and siliceous fine powder and / or limestone fine powder, and a cement composition containing cement and the cement admixture.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0006]
The expandable material of the present invention comprises free lime, calcium aluminoferrite, calcium ferrite and anhydrous gypsum as main constituent compounds. About the composition ratio, although it does not specifically limit, 30-70 parts of free lime are preferable in 100 parts of expansion | swelling materials, and 40-60 parts are more preferable. The calcium aluminoferrite is preferably 5 to 22.5 parts, more preferably 10 to 15 parts. The calcium ferrite is preferably 5 to 22.5 parts, more preferably 10 to 15 parts. Furthermore, 5-30 parts are preferable and, as for anhydrous gypsum, 10-30 parts are more preferable. If the composition ratio of each compound in the cement admixture is not within the above range, excellent expansion performance and fluidity retention performance may not be obtained. In addition, the part used by this invention and% represent a mass unit.
[0007]
The free lime of the present invention is usually called f-CaO.
The calcium aluminoferrite of the present invention is a generic term for the CaO—Al ₂ O ₃ —Fe ₂ O ₃ system and is not particularly limited, but in general, CaO is C, and Al ₂ O ₃ is When A and Fe ₂ O ₃ are F, compounds such as C ₄ AF, C ₆ A ₂ F, and C ₆ AF ₂ are well known, but it may be considered that they are usually present as C ₄ AF. . The calcium ferrite of the present invention is a generic term for CaO—Fe ₂ O ₃ system and is not particularly limited, but C ₂ F is well known. Hereinafter, in the present invention, calcium aluminoferrite is abbreviated as C ₄ AF, and calcium ferrite is abbreviated as C ₂ F.
[0008]
When producing the expandable material of the present invention, the CaO raw material, the Al ₂ O ₃ raw material, the Fe ₂ O ₃ raw material and the CaSO ₄ raw material are heat-treated to form a clinker made of free lime, C ₄ AF, C ₂ F and anhydrous gypsum. Is synthesized and manufactured. The effects of the present invention cannot be obtained when free lime, C ₄ AF, C ₂ F and anhydrous gypsum are synthesized separately and then mixed. Whether the clinker made of free lime, C ₄ AF, C ₂ F and anhydrous gypsum was synthesized by heat-treating the CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and CaSO ₄ raw material is, for example, pulverized performed microscopy of 100μm or more coarse particles in the object can be determined by confirming that free lime, C ₄ AF, the C ₂ F and anhydrous gypsum are mixed in the particles.
[0009]
Although it does not specifically limit as the heat processing method at the time of manufacture of this invention, It is preferable to bake in the temperature range of 1100-1600 degreeC using an electric furnace, a kiln, etc., and the temperature of 1200-1500 degreeC is preferable. A range is more preferred. If it is less than 1100 degreeC, the expansion | swelling performance of the obtained cement admixture is not enough, and when it exceeds 1600 degreeC, there exists a possibility that an anhydrous gypsum may decompose | disassemble.
[0010]
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 Fe ₂ O ₃ raw material include copper calami, iron powder, and commercially available iron oxide. Examples of the CaSO ₄ raw material include dihydrate gypsum, half water gypsum and anhydrous gypsum. Various impurities are present in these raw materials, and specific examples thereof include SiO ₂ , MgO, TiO ₂ , P ₂ O ₅ , Na ₂ O, K ₂ O and the like. However, SiO ₂ is particularly preferably in the range of less than 0.5 in terms of silicic acid. If the silicic acid ratio is 0.5 or more, an excellent expansion performance may not 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. Specifically, if it exceeds 5.0%, an excellent expansion performance may not be obtained.
[0011]
The particle size of the expanded material of the present invention is not particularly limited, usually, blurring - is preferably 1500~6000cm ² / g in down specific surface area, 2500~4000cm ² / g is more preferable. If it is less than 1500 cm < ² > / g, strength development may worsen, and if it exceeds 6000 cm < ² > / g, an excellent expansion performance may not be obtained.
[0012]
The siliceous fine powder used in the present invention is not particularly limited, but is a general term for silica fume, blast furnace slag, fly ash, silica dust such as diatomaceous earth and fused silica, and the like. The siliceous fine powder has the effect of improving the waterproof property of the concrete in addition to the effect of suppressing the pop-out phenomenon.
[0013]
The fine limestone powder used in the present invention is not particularly limited, but is a general term for ores composed mainly of calcium carbonate produced in nature. Limestone fine powder does not have the effect of improving waterproofness like siliceous fine powder, but has a sufficient effect of suppressing the pop-out phenomenon, and has an advantage that it can be obtained at a low cost depending on the region.
[0014]
The particle size of the siliceous fine powder and / or limestone fine powder used in the present invention is not particularly limited, but is usually preferably 3000 cm ² / g or more in terms of the specific surface area of the brain. If it is less than 3000 cm ² / g, a sufficient pop-out suppressing effect may not be obtained.
[0015]
The blending ratio of the expandable material of the present invention and the siliceous fine powder and / or limestone fine powder is not particularly limited, but usually the expandable material is preferably 50 to 95 parts in 100 parts of the cement admixture, 60 to 90 parts are more preferred. If the expansion material is less than 50 parts, sufficient expansion performance may not be obtained, and if it exceeds 95 parts, a sufficient pop-out phenomenon suppressing effect or waterproof improvement effect may not be obtained. The siliceous fine powder and / or limestone fine powder is preferably 5 to 50 parts, more preferably 10 to 40 parts. If it is less than 5 parts, there may be a case where a sufficient pop-out phenomenon suppressing effect and a waterproof effect cannot be obtained, and if it exceeds 50 parts, sufficient expansion performance may not be obtained.
[0016]
The blending amount of the cement admixture of the present invention is not particularly limited, but is usually preferably 5 to 15 parts, more preferably 7 to 13 parts in 100 parts of a cement composition composed of cement and a cement admixture. . If the amount is less than 5 parts, the effects of the present invention may not be sufficiently obtained. If the amount exceeds 15 parts, strength development may be deteriorated.
[0017]
As the cement of the present invention, various cements such as ordinary cement, early strength, very early strength, low heat and moderate heat, and mixed cement mixed with blast furnace slag, fly ash and silica, limestone powder, etc. are mixed. Filler cement, alumina cement, and the like, and one or more of these can be used.
[0018]
In addition to aggregates such as sand and gravel, the cement admixture and cement composition of the present invention, water reducing agent, high performance water reducing agent, AE water reducing agent, high performance AE water reducing agent, fluidizing agent, antifoaming agent, thickening agent. Agents, rust inhibitors, antifreeze agents, shrinkage reducing agents, polymer emulsions and setting modifiers, cement hardeners, cement expansion materials, clay minerals such as bentonite and zeolite, anion exchangers such as hydrotalcite, etc. It is possible to use 1 type (s) or 2 or more types in the range which does not substantially inhibit the objective of this invention.
[0019]
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 Nauta mixer.
[0020]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
[0021]
Example 1
The CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and CaSO ₄ raw material were blended, mixed and pulverized, and then heat treated at 1350 ° C. for 2 hours using an electric furnace to expand various compound compositions shown in Table 1. A material was produced and ground to a brain specific surface area of 3500 ± 200 cm ² / g. 75 parts of these expansion materials and 25 parts of limestone fine powder are mixed to form a cement admixture, and 10 parts of the cement admixture are blended in 100 parts of a cement composition composed of cement and cement admixture. Concrete having an amount of 300 kg / m ³ , a water / cement composition ratio = 62%, and s / a = 45% was prepared, and the length change rate, the slump reduction amount, and the pop-out test were performed. The results are also shown in Table 1.
The produced expanded material was identified by a powder X-ray diffractometer (XRD), and it was confirmed that free lime, C ₄ AF, C ₂ F and anhydrous gypsum were the main constituent compounds. The chemical composition was determined by chemical analysis, and the compound composition was determined by calculation based on the chemical analysis values. The expansion material R is prepared by separately synthesizing free lime, C ₄ AF, C ₂ F and anhydrous gypsum, and then mixing them.
[0022]
<Materials used>
Cement: Commercially available ordinary Portland cement limestone fine powder: pulverized limestone from Aomi mine, Niigata Prefecture, to a specific surface area of 5000 cm ² / g.
Water: tap water sand: produced in Himekawa, Niigata Prefecture, specific gravity 2.62
Gravel: Niigata prefecture Himekawa production, specific gravity 2.64
CaO raw material: Reagent primary calcium carbonate Al ₂ O ₃ raw material: Reagent primary aluminum oxide Fe ₂ O ₃ raw material: Reagent primary iron oxide CaSO ₄ raw material: Reagent primary anhydrous gypsum
<Measurement method>
Chemical analysis: Measured according to JIS R 5202.
Compound composition: Free lime content was measured according to JIS R 5202, and other compounds were calculated. That is, the C ₄ AF amount was calculated from the Al ₂ O ₃ amount, the C ₂ F amount was calculated from the remaining Fe ₂ O ₃ amount, and then the anhydrous gypsum amount was calculated from the SO ₃ amount.
Length change rate: Measured according to JIS A 6202 B.
Slump reduction: Measures slump according to JIS A 1101, and displays it as the value obtained by subtracting the slump value after 60 minutes from the slump value immediately after kneading. The environmental temperature was 30 ° C.
Pop-out test: Concrete is prepared in advance without adding cement admixture, concrete is put into the tilting mixer, and the cement admixture is moved while agitating the mixer at a speed of 12 revolutions / minute. It was added, discharged 10 minutes later, and placed in a mold having a length of 1 m, a width of 50 cm, and a height of 10 cm, and a pop-out phenomenon was confirmed. The ambient temperature was 20 ° C.
[0024]
[Table 1]

[0025]
From Table 1, it can be seen that the cement admixture and the cement composition of the present invention impart excellent expansion performance and fluidity retention performance to concrete and prevent pop-out phenomenon.
[0026]
Example 2
An industrial material, CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and CaSO ₄ raw material were blended and heat-treated at 1400 ° C. using a rotary kiln to produce an expansion material having the composition shown in Table 2. Except for this, the same procedure as in Example 1 was performed. Table 3 shows the compound composition calculated from the chemical composition, and Table 4 shows the measurement results. For comparison, the same experiment was performed on two types of commercially available expansion materials.
[0027]
<Materials used>
CaO raw material: Limestone Al ₂ O ₃ raw material from Aomi mine, Niigata Prefecture: Chinese bauxite Fe ₂ O ₃ raw material: Industrial iron oxide CaSO ₄ raw material: Thai natural anhydrous gypsum commercial expansion material A: Calcium sulfoaluminate Expandable material Commercially expanded material B: Lime-based expanded material [0028]
[Table 2]

[0029]
[Table 3]

[0030]
[Table 4]

[0031]
From Table 4, it can be seen that the cement admixture and cement composition of the present invention impart excellent expansion performance and fluidity retention performance to concrete, and prevent pop-out phenomenon.
[0032]
Example 3
The same procedure as in Example 2 was performed except that the expansion material of the present invention of Example 2 was used and the cement admixture was changed by changing the type and amount of the siliceous fine powder shown in Table 5. A waterproof test was also conducted. The results are also shown in Table 5.
[0033]
<Materials used>
Siliceous fine powder (1): Commercially available blast furnace slag ground to a specific surface area of 5000 cm ² / g.
Siliceous fine powder (2): Commercially available silica fume, brain specific surface area of 200,000 cm ² / g.
Silica fine powder (3): Commercially available fly ash ground to a specific surface area of 5000 cm ² / g.
Siliceous fine powder (4): A commercially available diatomaceous earth ground to a brain specific surface area of 5000 cm ² / g.
Siliceous fine powder (5): A mixture of equal amounts of siliceous fine powder (1) and siliceous fine powder (2), brain specific surface area of 102500 cm ² / g.
Siliceous fine powder (6): Silica fine powder (2) and an equivalent mixture of limestone fine powder, brain specific surface area of 102500 cm ² / g.
[0034]
<Measurement method>
Waterproof test: A circular empty specimen with a diameter of 15 x 30 cm and a center hole diameter of 2.0 cm was prepared. After demolding at a material age of 1 day, it was subjected to underwater curing for 6 days until the material age of 7 days, and then water permeability The test was conducted. When the test method is an output method, water pressure of 10 kg / cm ² is applied from the outside of the specimen for 48 hours, the amount of water coming out from the center hole is measured, and the water permeability of the concrete containing no cement admixture is 100 The relative value was expressed as a water permeability ratio.
[0035]
[Table 5]

[0036]
From Table 5, it can be seen that the cement admixture and the cement composition of the present invention impart excellent expansion performance to concrete, prevent pop-out phenomenon, and improve waterproofness.
[0037]
Example 4
A cement admixture prepared by mixing 75 parts of the expansion material of the present invention of Example 2 and 25 parts of siliceous fine powder (2) was used. Table 6 shows the blending amount of the cement admixture in the cement composition. The procedure was the same as in Example 2 except that the changes were made as shown. Further, the compressive strength at the age of 28 days was measured. The results are also shown in Table 6.
[0038]
<Measurement method>
Compressive strength: Measured according to JIS A 1108.
[0039]
[Table 6]

[0040]
From Table 6, the cement admixture of the present invention gives an excellent expansion performance in which the rate of change in the length of the concrete increases as the blending amount increases, and prevents pop-out phenomenon and enhances waterproofness. I understand.
[0041]
【The invention's effect】
The cement admixture of the present invention imparts excellent expansion performance and fluidity retention performance to concrete even when the blending amount is small, and can prevent pop-out phenomenon and improve waterproofness.

Claims (2)

An expansion material produced by heat-treating a CaO raw material, an Al ₂ O ₃ raw material, an Fe ₂ O ₃ raw material and a CaSO ₄ raw material to synthesize a clinker made of free lime, calcium aluminoferrite, calcium ferrite and anhydrous gypsum; A cement admixture containing siliceous fine powder and / or limestone fine powder.   A cement composition comprising cement and the cement admixture according to claim 1.