JP3818802B2 - Cement admixture and cement composition - Google Patents

Description

【００３０】
【表２】

【００３１】
表２より、本発明のセメント混和材は、膨張性能、貯蔵安定性に優れ、しかもポップアウト現象を防止していることが判る。
【００３２】
実施例２
工業原料であるＣａＯ原料、Ａｌ₂Ｏ₃原料、Ｆｅ₂Ｏ₃原料及びＣａＳＯ₄原料を配合して、ロータリーキルンを用いて、１４００℃で熱処理することによって、表３に示す組成の膨張物質を製造したこと以外は実施例１と同様に行った。表４に化学組成から算出した化合物組成を示し、膨張率の測定結果を表５に示す。尚、比較のために、市販の２種類のセメント混和材についても同様の実験を行った。
＜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
Ｆｅ₂Ｏ₃原料：工業用酸化鉄
ＣａＳＯ₄原料：タイ産天然無水セッコウ
膨張材Ａ：市販カルシウムサルホアルミネート系膨張材
膨張材Ｂ：市販生石灰系膨張材
【００３３】
【表３】

【００３４】
【表４】

【００３５】
【表５】

【００３６】
表５より、本発明のセメント混和材は、膨張性能に優れ、しかもポップアウト現象を防止していることが判る。
【００３７】
実施例３
実施例２の本発明の膨張物質を使用し、表６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。尚、防水性試験も併せて実施した。その結果を表６に併記する。
【００３８】
＜使用材料＞
シリカ質微粉末▲１▼：市販の高炉スラグをブレーン比表面積５０００ｃｍ²／ｇに粉砕したもの。
シリカ質微粉末▲２▼：市販のシリカフューム、ブレーン比表面積２０００００ｃｍ²／ｇ。
シリカ質微粉末▲３▼：市販のフライアッシュをブレーン比表面積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ーン比表面積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▼の等重量混合物、ブレーン比表面積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重量混合物、ブレーン比表面積１０２５００ｃｍ²／ｇ。
＜測定方法＞
防水性試験：φ１５×３０ｃｍ、中心孔の直径２．０ｃｍの円空供試体を作製し、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。試験はアウトプット方法とし、試験体外側から水圧１０ｋｇ／ｃｍ²を４８時間加え、中心孔からにじみ出る水量を測定し、セメント混和材を混和しないコンクリートの透水量を１００とした時の相対値を透水比として表した。
【００３９】
【表６】

【００４０】
表６より、本発明のセメント混和材は、膨張性能に優れ、しかもポップアウト現象を防止し、防水性が高いことが判る。
【００４１】
実施例４
実施例２の本発明の膨張物質７５重量部とシリカ質微粉末▲２▼の２５重量部からなるセメント混和材を使用し、セメント組成物１００重量部中、セメント混和材の配合量を表７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。その結果を表７に併記する。
【００４２】
【表７】

【００４３】
表７より、本発明のセメント混和材を配合したコンクリートは、配合量が増加するに伴い膨張率は高まり、ポップアウト現象を防止すると共に、防水性が高くなることが判る。
【００４４】
【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、優れた膨張性能を付与し、ポップアウト現象の防止、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 civil engineering and construction industries.
[0002]
[Prior art]
Cement is an excellent material that is inexpensive and can be used to build large concrete structures into any shape. Furthermore, the strength and durability of the structure can be improved by using a cement admixture together. Many cement admixtures have been proposed so far, and the most used one is a cement admixture that imparts expansibility to concrete. Here, concrete is a general term for cement, mortar, and concrete.
[0003]
As cement admixtures that impart expansibility to concrete structures, for example, those containing CaO—Al ₂ O ₃ —SO ₃ compounds as active ingredients are known (Japanese Patent Publication No. 42-21840, Japanese Patent Publication No. Sho). 42-19473, JP-B 53-16007, etc.).
[0004]
[Problems to be solved by the invention]
However, since these cement admixtures are introduced into a concrete bag and mixed with concrete in a raw plant, the cement admixtures may be shipped without being sufficiently kneaded in some cases. In such a case, the cement admixture is often agglomerated without being uniformly dispersed in the concrete, and in the concrete after hardening, the agglomerated cement admixture locally causes abnormal expansion, It has been regarded as a problem to cause a so-called pop-out phenomenon in which the surface of the cured body swells macroscopically, peels off or falls.
[0005]
As a method of preventing the pop-out phenomenon, inactive inorganic powder or the like is mixed in advance with the expansion material, and even if the cement admixture is not sufficiently kneaded, the expansion components do not aggregate and become a lump. A method that allows a certain degree of dispersion to be expected is conceivable, but by adding inert inorganic powder, the expansion component is diluted and the amount of cement admixture added to give the required performance increases. Problem arises.
[0006]
Recently, the performance required for cement admixtures that impart expansibility has been increasing. That is, the actual situation is that development of a cement admixture that can provide excellent expansion performance even with a small blending amount is awaited. Therefore, although the method of increasing the blending amount of the cement admixture is not beneficial, even though it is for preventing the popout phenomenon, it is necessary to find a method that can prevent the popout phenomenon without increasing the blending amount.
[0007]
On the other hand, a cement admixture that gives waterproofness to concrete is also demanded. Therefore, in view of such circumstances, the present inventors have made various studies in order to solve the above-mentioned problems, and as a result, the above-mentioned problems can be solved by blending a specific expansion substance with fine siliceous powder and / or fine limestone powder. The present invention has been completed by obtaining the knowledge that a cement admixture capable of eliminating the above can be obtained.
[0008]
[Means for Solving the Problems]
That is, the present invention, CaO material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and heat treatment of the CaSO ₄ material, free lime, calcium aluminosilicate Blow wells, the 及 beauty anhydrous gypsum in inflation material to configure compound there, during the inflation material, free lime of 30 to 60 wt%, calcium alumino ferrite 10 to 40 wt%, and the inflation material anhydrous gypsum is 10 to 40 wt%, siliceous fine powder and / or limestone A cement admixture comprising a fine powder, wherein the expansion material is 50 to 95 parts by weight in 100 parts by weight of the cement admixture, and contains the cement and the cement admixture. Ri cement composition der formed by cement admixture is, in the cement composition 100 parts by weight, the cement composition is 3-12 parts by weight, cement and, CaO material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and a CaSO ₄ material heat treatment And, free lime, calcium alumino ferrite, and a inflation material to anhydrous gypsum structure compound, in the inflation material, free lime of 30 to 60 wt%, calcium alumino ferrite 10 to 40% by weight, and anhydrous gypsum There Ru cement composition der which comprises an expansion material is 10-40 wt%, and a siliceous fine powder and / or limestone powder.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0010]
The expansion material of the present invention is mainly composed of free lime, calcium aluminoferrite and anhydrous gypsum, and the ratio thereof is not particularly limited, but the free lime is preferably 30 to 60%, and 40 to 50%. Is more preferable. The calcium aluminoferrite is preferably 10 to 40%, more preferably 15 to 30%. Anhydrous gypsum is preferably 10 to 40%, more preferably 20 to 35%. If the ratio of each compound in the expansion material is out of the above range, an excellent expansion characteristic may not be obtained. Here,% indicates a weight percentage.
[0011]
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. Usually, it is considered that C ₄ AF exists, and in the present invention, calcium aluminoferrite is hereinafter referred to as C ₄ AF.
[0012]
When producing the cement admixture 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 synthesize a clinker composed of free lime, C ₄ AF and anhydrous gypsum. It is manufactured by crushing this. In the case where free lime, C ₄ AF and anhydrous gypsum are synthesized separately and mixed, the effect as in the present invention cannot be obtained. Whether the clinker composed of free lime, C ₄ AF and anhydrous gypsum was synthesized by heat-treating the CaO raw material, the Al ₂ O ₃ raw material, the Fe ₂ O ₃ raw material and the CaSO ₄ raw material is, for example, 100 μm or more in the pulverized product These coarse particles can be discriminated by microscopic observation and confirming that free lime, C ₄ AF and anhydrous gypsum are mixed in the particles.
[0013]
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 performance of the obtained cement admixture is not enough, and when it exceeds 1600 degreeC, anhydrous gypsum may decompose | disassemble.
[0014]
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, in particular, SiO ₂ is preferably in a 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 rate 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 cement admixture.
Silicic acid ratio = SiO ₂ / (Al ₂ O ₃ + Fe ₂ O ₃ )
[0015]
The amount of SiO ₂ in the cement admixture is preferably 5.0% or less, more preferably 3.0% or less. Specifically, if it exceeds 5.0%, an excellent expansion performance may not be obtained.
[0016]
The particle size of the expansion material of the present invention is not particularly limited, but usually it is preferably 1500 to 6000 cm ² / g, more preferably 2500 to 4000 cm ² / g in terms of the specific surface area of Blaine. 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.
[0017]
The siliceous fine powder of the present invention is not particularly limited, but is a general term for silica fume, blast furnace slag, fly ash, diatomaceous earth, silica dust such as fused silica, and the like. The siliceous fine powder has the effect of improving the waterproof property of concrete in addition to the effect of suppressing the pop-out phenomenon.
[0018]
Although the limestone fine powder of the present invention is not particularly limited, it is a general term for ores composed mainly of calcium carbonate produced in nature. Limestone fine powder, unlike siliceous fine powder, does not have the effect of improving waterproofness, but has a sufficient effect of suppressing the pop-out phenomenon, and further has an advantage that it can be obtained at a low cost depending on the region.
[0019]
The particle size of the siliceous fine powder and / or limestone fine powder of the present invention is not particularly limited, but is usually preferably 3000 to 9000 cm ² / g, more preferably 3500 to 6000 cm ² / g in terms of the specific surface area of Blaine. . If it is less than 3000 cm ² / g, there may be a case where a sufficient effect of suppressing the pop-out phenomenon cannot be obtained, and if it exceeds 9000 cm ² / g, further enhancement of the effect cannot be expected, and the economic burden increases.
[0020]
The blending ratio of the expansion substance in the cement admixture of the present invention and the siliceous fine powder and / or limestone fine powder is not particularly limited, but normally, the expansion substance is 50 parts in 100 parts by weight of the cement admixture. -95 weight part is preferable and 60-90 weight part is more preferable. If the expansion material is less than 50 parts by weight, sufficient expansion performance may not be obtained, and if it exceeds 95 parts by weight, there may be cases where sufficient pop-out phenomenon suppression effect and waterproofing improvement effect cannot be obtained. is there. The siliceous fine powder and / or limestone fine powder is preferably 5 to 50 parts by weight, and more preferably 10 to 40 parts by weight. If the amount is less than 5 parts by weight, there may be a case where a sufficient pop-out phenomenon suppressing effect and a waterproof effect cannot be obtained. If the amount exceeds 50 parts by weight, sufficient expansion performance may not be obtained.
[0021]
Although the particle size of the cement admixture of the present invention is not particularly limited, it is usually preferably 2500 to 6000 cm ² / g, more preferably 3000 to 5000 cm ² / g in terms of Blaine specific surface area. If it is less than 2500 cm ² / g, a sufficient pop-out phenomenon suppressing effect may not be obtained, and if it exceeds 6000 cm ² / g, an excellent expansion performance may not be obtained.
[0022]
The blending amount of the cement admixture of the present invention is not particularly limited, but usually 3 to 12 parts by weight, preferably 5 to 9 parts by weight, in 100 parts by weight of cement composition composed of cement and cement admixture. Is more preferable. If the amount is less than 3 parts by weight, the effects of the present invention may not be sufficiently obtained. If the amount exceeds 12 parts by weight, strength development may be deteriorated.
[0023]
The cement according to the present invention includes various portland cements specified in JIS R 5210, various mixed cements specified in JIS R 5211, JIS R 5212, JIS R 5213, and admixtures mixed in a range exceeding the range specified in JIS. Blast furnace cement, fly ash cement and silica cement, filler cement mixed with limestone powder, alumina cement and the like can be used, and one or more of these can be used.
[0024]
The cement composition comprising the cement of the present invention and a cement admixture is used as cement mortar or cement concrete by mixing with aggregates such as sand and gravel as well as being used as a cement paste as it is. . In the present invention, further, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, antifoaming agent, thickening agent, rust preventive agent, antifreezing agent, shrinkage reducing agent, polymer emulsion, setting modifier , One or more of cement rapid hardening materials, clay minerals such as bentonite and zeolite, ion exchangers such as hydrotalcite, etc. may be used within a range that does not substantially impair the object of the present invention. Is possible.
[0025]
In the present invention, the mixing method of each material is not particularly limited as long as all the respective materials are mixed in advance . As the mixing device, any existing device can be used, and for example, a tilting barrel mixer, an omni mixer, a Henschel mixer, a V-type mixer, a nauter mixer, and the like can be used.
[0026]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
[0027]
Example 1
Blending CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and CaSO ₄ raw material, mixing and pulverizing, heat treatment at 1350 ° C. for 2 hours to produce expanded materials with various compositions shown in Table 1, The specific surface area was pulverized to 3500 ± 200 cm ² / g. 75 parts by weight of these expansion materials and 25 parts by weight of limestone fine powder are mixed to obtain a cement admixture, and 7 parts by weight of cement admixture is blended in 100 parts by weight of cement composition composed of cement and cement admixture. Concrete having a cement composition amount of 300 kg / m ³ , a water / cement composition ratio of 62%, and an s / a of 45% was prepared, and an expansion coefficient was measured and a pop-out test was performed. In order to check the storage stability of the cement admixture, put the cement admixture in a paper bag and close it with a sewing machine and store it in a test room at a temperature of 20 ° C and a relative humidity of 80% for one month. The expansion rate at the age of 7 days was measured. The test results are shown in Table 2. Incidentally, the expanded material was identified by powder X-ray diffractometry (XRD), it was free lime, the C ₄ AF, and anhydrous gypsum sure that the main constituent compounds. The chemical composition was determined by chemical analysis, and the compound composition was calculated by calculation from the result of chemical analysis.
[0028]
<Materials used>
Cement: Commercially available ordinary Portland cement limestone fine powder: pulverized limestone from the Aomi mine in Niigata Prefecture to a brain 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 special grade calcium carbonate Al ₂ O ₃ raw material: Reagent special grade aluminum oxide Fe ₂ O ₃ raw material: Reagent first grade iron oxide CaSO ₄ raw material: Reagent special grade 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 determined by calculation. That is, the amount of C ₄ AF was calculated from the amount of Fe ₂ O ₃ , and then the amount of anhydrous gypsum was calculated from the amount of SO ₃ .
Expansion coefficient: Measured according to JIS A 6202 B.
Pop-out test: Concrete is prepared in advance without adding cement admixture, this concrete is put into a tilting mixer, and cement admixture is added after agitating the mixer at a speed of 12 rotations / min. After discharging for a minute, the sample was discharged into 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 observed.
[0029]
[Table 1]

[0030]
[Table 2]

[0031]
From Table 2, it can be seen that the cement admixture of the present invention has excellent expansion performance and storage stability, and also prevents the pop-out phenomenon.
[0032]
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 are blended and heat-treated at 1400 ° C. using a rotary kiln to produce an expanded material having the composition shown in Table 3. Except that, the same procedure as in Example 1 was performed. Table 4 shows the compound composition calculated from the chemical composition, and Table 5 shows the measurement results of the expansion coefficient. For comparison, the same experiment was performed on two commercially available cement admixtures.
<Materials used>
CaO raw material: Limestone Al ₂ O ₃ raw material from Qinghai mine, Niigata Prefecture: Chinese bauxite Fe ₂ O ₃ raw material: Industrial iron oxide CaSO ₄ raw material: Thai natural anhydrous gypsum expansion material A: Commercial calcium sulfoaluminate expansion material expansion Material B: Commercial quicklime expansion material
[Table 3]

[0034]
[Table 4]

[0035]
[Table 5]

[0036]
From Table 5, it can be seen that the cement admixture of the present invention is excellent in expansion performance and prevents the pop-out phenomenon.
[0037]
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 type and amount of the siliceous fine powder shown in Table 6 was changed to obtain a cement admixture. A waterproof test was also conducted. The results are also shown in Table 6.
[0038]
<Materials used>
Siliceous fine powder {circle around (1)}: Commercially available blast furnace slag ground to a brain specific surface area of 5000 cm ² / g.
Siliceous fine powder (2): Commercially available silica fume, Blaine specific surface area of 200,000 cm ² / g.
Siliceous fine powder (3): Commercially available fly ash pulverized to a brain specific surface area of 5000 cm ² / g.
Siliceous fine powder (4): Commercially available diatomaceous earth ground to a brain specific surface area of 5000 cm ² / g.
Siliceous fine powder (5): A mixture of equal weight of siliceous fine powder (1) and siliceous fine powder (2), Blaine specific surface area of 102500 cm ² / g.
Siliceous fine powder (6): Equal weight mixture of siliceous fine powder (2) and limestone fine powder, Blaine specific surface area of 102500 cm ² / g.
<Measurement method>
Waterproof test: A circular empty specimen having a diameter of 15 cm × 30 cm and a center hole diameter of 2.0 cm was prepared. After demolding at a material age of 1 day, after being subjected to underwater curing for 6 days until a material age of 7 days, water permeability The test was conducted. The test is an output method, a water pressure of 10 kg / cm ² is applied from the outside of the specimen for 48 hours, the amount of water that exudes from the center hole is measured, and the relative value when the water permeability of concrete that does not contain cement admixture is taken as 100 is the water permeability. Expressed as a ratio.
[0039]
[Table 6]

[0040]
From Table 6, it can be seen that the cement admixture of the present invention is excellent in expansion performance, prevents pop-out phenomenon, and is highly waterproof.
[0041]
Example 4
A cement admixture consisting of 75 parts by weight of the expansion material of the present invention of Example 2 and 25 parts by weight of siliceous fine powder (2) was used, and the blending amount of the cement admixture in 100 parts by weight of the cement composition is shown in Table 7. Example 2 was carried out in the same manner as in Example 2 except that the change was made. The results are also shown in Table 7.
[0042]
[Table 7]

[0043]
From Table 7, it can be seen that the concrete blended with the cement admixture of the present invention increases in expansion rate as the blending amount increases, preventing the pop-out phenomenon and increasing the waterproofness.
[0044]
【The invention's effect】
The cement admixture of the present invention imparts excellent expansion performance even when the blending amount is small, and can prevent pop-out phenomenon and improve waterproofness.

Claims (5)

CaO raw material was heat-treated Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and a CaSO ₄ material, free lime, calcium aluminosilicate Blow wells, the 及 beauty anhydrous gypsum a inflation material to configure compounds, the inflation material among contains free lime of 30 to 60 wt%, calcium alumino ferrite 10 to 40 wt%, and the inflation material anhydrous gypsum is 10 to 40 wt%, and a siliceous fine powder and / or limestone powder A cement admixture. Expansion material is cement admixture 100 In parts by weight, 50 ~ 95 The cement admixture according to claim 1, which is part by weight. A cement composition comprising cement and the cement admixture according to claim 1 or 2 . Cement admixture is a cement composition 100 3 parts by weight 12 The cement composition according to claim 3, wherein the cement composition is part by weight. Cement, CaO material, Al ₂ O _Three material, Fe ₂ O _Three Raw materials, and CaSO _Four A swelling material comprising heat-treated raw lime, free lime, calcium aluminoferrite, and anhydrous gypsum as constituent compounds, wherein the free lime is contained in the swelling material 30 ~ 60 % By weight, calcium aluminoferrite Ten ~ 40 % By weight, and anhydrous gypsum Ten ~ 40 A cement composition comprising a swelling material in weight% and fine siliceous powder and / or fine limestone powder.