JP2002167253A - Cement admixture and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement admixture and a cement composition more excellent in expansive performance and higher strength development than conventional. SOLUTION: The cement admixture obtained by heat treating the combination of CaO raw material, Fe2O3 raw material, CaSO raw material, and if necessary Al2O3 raw material, contains free lime, calcium ferrite and/or calcium alumino ferrite, and expansive matter containing anhydrous gypsum and alkanolamines. The cement composition is constituted of a cement and the above cement admixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement admixture and a cement composition mainly used in the fields of civil engineering and construction.

[0002]

2. Description of the Related Art It is important to reduce the cracks and improve the bending strength of cement and concrete from the viewpoints of reliability, durability, aesthetics, etc. of concrete structures. There is a need for further technological advances in cement based expanders. Conventionally, as a cement admixture that gives expandability to cement / concrete, for example, a free lime-auin-anhydrous gypsum-based expanding material (Japanese Patent Publication No. 42-21840) and a free lime-calcium silicate-anhydrous gypsum-based expansion Lumber (Japanese Patent Publication No. 53-3)
No. 1170). Further, a cement admixture containing calcium ferrite and / or calcium aluminoferrite has also been proposed. For example, JP-A-49-814
No. 34 discloses free lime and calcium ferrite and / or
Alternatively, a technique is disclosed in which clinker made of calcium alumino ferrite is produced and crushed, and then mixed with gypsum dihydrate.

[0003]

However, in such a cement admixture, not only the expansion performance is not sufficient, but also the free lime in the cement admixture is easily weathered and the quality stability is poor. In recent years, high fluidity concrete and high-strength concrete have been actively developed for the purpose of improving the performance of concrete. In fact, the development of an expandable material capable of imparting a large expandability even if the mixing ratio of the expandable material is small has been awaited. Furthermore, when a conventional cement admixture giving expansion properties is used, there is also a problem that the strength of cement concrete using the cement admixture is slightly reduced due to expansion. The present inventors have conducted various studies to solve these problems, and as a result, obtained the knowledge that the problems can be solved by using a specific cement admixture, and completed the present invention. Was.

[0004]

That is, the present invention provides CaO
A material obtained by blending an Al ₂ O ₃ raw material with a raw material, a Fe ₂ O ₃ raw material and a CaSO ₄ raw material as necessary, and heat-treating the raw material, free lime, calcium ferrite and / or calcium alumino ferrite, and anhydrous A cement admixture containing an expanding substance containing gypsum and an alkanolamine, and a cement composition containing cement and the cement admixture.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

[0006] The expanding material of the present invention comprises a CaO raw material, Fe ₂
A substance obtained by blending an Al ₂ O ₃ raw material as necessary with an O ₃ raw material and a CaSO ₄ raw material and heat-treating the raw material, containing free lime, calcium ferrite and / or calcium alumino ferrite, and anhydrous gypsum. It is. The proportion is not particularly limited, but free lime, calcium ferrite and / or calcium aluminoferrite, and in 100 parts of the expanded material containing anhydrous gypsum, free lime is preferably 20 to 65 parts, and 30 parts by weight. ~ 55 parts is more preferred. In addition, calcium ferrite and / or calcium alumino ferrite are 1
0 to 55 parts is preferable, and 15 to 45 parts is more preferable.
Further, the amount of anhydrous gypsum is preferably 5 to 40 parts,
30 parts is more preferred. If the composition ratio of each compound in the clinker is not in the above range, excellent expansion performance may not be obtained. In addition, the part and% which show the mixing ratio used by this invention are a mass unit.

[0007] The calcium ferrite of the present invention is Ca
O—Fe ₂ O ₃ is a general term for compounds and is not particularly limited, but generally, CaO is C, Fe ₂
Assuming that O ₃ is F, compounds such as C ₂ F and CF are well known. Usually, it can be considered that it exists as C ₂ F. In the present invention, calcium ferrite is hereinafter referred to as C ₂ F
Abbreviated. The calcium alumino ferrite of the present invention is a general term for CaO-Al ₂ O ₃ -Fe ₂ O ₃ -based compounds, and is not particularly limited.
When CaO is C, Al ₂ O ₃ is A, and Fe ₂ O ₃ is F, C
Compounds such as 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 alumino ferrite is hereinafter referred to as C ₄ AF
Abbreviated.

In producing the expanding material of the present invention, CaO
Material, Fe_TwoO_ThreeRaw materials and CaSO_FourA as needed for raw materials
l_TwoO_ThreeThe raw materials are blended and heat treated, free lime and C_TwoF and
And / or C_FourClinker consisting of AF and anhydrous gypsum
Is synthesized and pulverized to be produced. Free lime, C_Two
F and / or C_FourAF or part of anhydrous gypsum
Are synthesized separately, and a mixture of these
The effect like the invention cannot be obtained. CaO raw material, Fe_TwoO_Three
Raw materials and CaSO_FourAl if necessary_TwoO _ThreeRaw materials
Heat the blended material to remove free lime and C_TwoF and / or
Is C_FourSynthesizes clinker consisting of AF and anhydrous gypsum
And confirm that it is manufactured by crushing it.
As a method, for example, coarse particles of cement admixture, concrete
Observation of particles larger than 100 μm with a microscope
To analyze the composition and find free lime and C in the particles._TwoF and / or
Or C_FourCheck that AF and anhydrous gypsum are mixed.
It can be easily identified by confirming.

The heat treatment temperature for producing the cement admixture of the present invention is preferably in the range of 1100 to 1600 ° C, more preferably in the range of 1200 to 1500 ° C. 1
If the temperature is lower than 100 ° C., the obtained cement admixture has insufficient expansion performance. If the temperature exceeds 1600 ° C., anhydrous gypsum may be decomposed.

Examples of the CaO raw material include limestone and slaked lime, and examples of the Fe ₂ O ₃ raw material include various industrial by-products called Karami and industrial by-products called rolling scale.
Alternatively, commercially available iron oxide or iron powder may be used, and CaSO ₄
Raw materials include gypsum dihydrate, hemihydrate gypsum and anhydrous gypsum, and examples of Al ₂ O ₃ raw materials include bauxite and aluminum residual ash.

[0011] These raw materials contain impurities. Specific examples include SiO ₂ , MgO, TiO ₂ , P ₂ O ₅ ,
_{Na 2 O, K 2 O,} CuO, ZnO, Ag 2 O , and the like, although no particular problem in the range that does not substantially impair the object of the present invention, among these, in particular, SiO ₂ is silica It is preferable that the ratio be less than 1.0. When the silicate ratio is 1.0 or more, excellent expansion performance may not be obtained. The silicic acid ratio as referred to in the present invention refers to the S content in the cement admixture.
It is calculated from the following equation from the amount of iO _{2, the} amount of Al ₂ O _{3 and the} amount of Fe ₂ O ₃ . Silicic acid ratio = SiO ₂ / (Al ₂ O ₃ + Fe ₂ O ₃ ) The amount of SiO ₂ in the cement admixture is preferably 5.0% or less, more preferably 3.0% or less. If it exceeds 5.0%, excellent expansion performance may not be obtained.

[0012] The particle size of the cement admixture of the present invention is not particularly limited.
00 to 9000 cm ² / g is preferable, and 2500 to 40
00 cm ² / g is more preferred. If the particle size of the cement admixture is less than 1500 cm ² / g, long-term durability may be deteriorated, and if it exceeds 9000 cm ² / g, sufficient expansion performance may not be obtained.

In the present invention, a material obtained by blending a CaO raw material, an Fe ₂ O ₃ raw material, and a CaSO ₄ raw material with an Al ₂ O ₃ raw material as necessary and heat-treating it, comprising free lime, calcium ferrite and / or Alternatively, when pulverizing the expandable substance containing calcium aluminoferrite and anhydrous gypsum, it is preferable to use a pulverization aid from the viewpoint of improving pulverization efficiency. As the grinding aid, a grinding aid used when grinding Portland cement clinker can be used. Many pulverization assistants have been proposed so far, but recently, pulverization aids that not only improve the pulverization efficiency but also have a strength increasing effect have been developed, and they are used in the present invention. Alkanolamines are known as grinding aids that also have a strength enhancing effect.

The alkanolamines of the present invention are not particularly limited, but as a specific example, for example, US Pat. No. 2,203,621 discloses a technique using triethanolamine. JP-A-3-183647 discloses hydroxyl groups such as triisopropanolamine, N, N-bis- (2-hydroxyethyl) -N- (2-hydroxypropyl) -amine and tris- (2-hydroxybutyl) -amine. A technique using a higher trialkanolamine having an amino group is disclosed. Also, JP-A-10-32455
No. 0 discloses an alkanolamine having an ionic functional group other than a hydroxyl group. Specific examples of alkanolamines having an ionic functional group other than a hydroxyl group include 1- (bis-2-hydroxypropylamino) -2
-Propyl maleate, 1- (bishydroxyethyl) amino-2-hydroxy-propylsulfonic acid, sodium 1- (bis-2-hydroxypropyl) aminopropionate, sodium 1- (bishydroxyethyl) aminopropionate and the like Is mentioned. The present invention also includes potassium salts, calcium salts, magnesium salts, ammonium salts and the like in addition to the above-mentioned alkanolamines and the sodium salts thereof. These alkanolamines have been proposed as a grinding aid for Portland cement clinker.However, the present inventors have found that when producing the intumescent material of the present invention, as a grinding aid or as an additive after grinding. It has been found that the addition of these alkanolamines increases the 28-day strength of cement concrete using the cement admixture of the present invention, and also improves the expansion performance.

Although the amount of the alkanolamine is not particularly limited, it is usually preferably used in the range of 0.01 to 2 parts, more preferably 0.05 to 1 part. If the amount is less than 0.01 part, the effect of increasing the pulverization efficiency and the strength is not sufficient, and even if the amount is more than 2 parts, the effect is not improved and it is not preferable in terms of economy.

Although the amount of the cement admixture of the present invention is not particularly limited, it is usually preferably 3 to 12 parts, and more preferably 5 to 9 parts in 100 parts of a cement composition comprising cement and the cement admixture. Is more preferred. In less than 3 parts,
Sufficient inflation performance may not be obtained, and over 12 parts may cause overexpansion.

As the cement of the present invention, there are various portland cements such as ordinary cement, high-strength, super-high-strength, low heat and moderate heat, various cements obtained by mixing blast furnace slag, fly ash and silica with these cements, and limestone. There is a filler cement mixed with powder and the like.

In the present invention, a water reducing agent, a high-performance water reducing agent, AE
Water reducing agent, high-performance AE water reducing agent, superplasticizer, defoamer, thickener, rust inhibitor, anti-freezing agent, shrinkage reducing agent, polymer emulsion and setting accelerator, setting retarder, and cement hardening material,
It is possible to use one or more of clay minerals such as bentonite and anion exchangers such as hydrotalcite, boric acid and salts thereof within a range that does not substantially inhibit the object of the present invention. .

In the present invention, the method of mixing the respective materials is not particularly limited, and the respective materials may be mixed at the time of construction, or some or all of them may be mixed in advance. . As the mixing device, any existing device can be used, and examples thereof include a tilting mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauter mixer.

[0020]

The present invention will be described below in detail with reference to examples.

Example 1 A raw material of Ca ₂ O _{3, a} raw material of Fe ₂ O _{3, and a} raw material of CaSO ₄ were blended with a raw material of Al ₂ O _{3 as} necessary and mixed and pulverized.
Clinker having the composition shown in Table 1 was synthesized by heat treatment at 0 ° C. for 3 hours. 0.05 parts of the grinding aid A or B was used for 100 parts of the clinker, and the mixture was pulverized to a Blaine specific surface area of 3500 ± 300 cm ² / g using a ball mill to prepare a cement admixture. When the cement admixture was identified by powder X-ray diffraction, free lime, C ₂ F and / or C
₄ AF and anhydrous gypsum. 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. In 100 parts of a cement composition composed of cement and a cement admixture, 7 parts of a cement admixture was used, and a water / cement composition ratio = 47.
%, A mortar having a cement composition / sand ratio = 1/3 was prepared, and the length change rate and the compressive strength were measured. The length change rate indicates the measurement result of the cement admixture pulverized using the pulverization aid A. The compressive strength is expressed as a relative value of the compressive strength when using the cement admixture crushed using the grinding aid A with respect to the compressive strength when using the cement admixture crushed using the crushing aid B. did. For comparison, free lime, C ₂ F and / or C ₄ AF, and part or all of anhydrous gypsum were separately synthesized and pulverized.
The same experiment was performed on cement admixtures blended so that the compound compositions were the same as Nos. 1-5, 1-15, and 1-16 (Experiments Nos. 1-17 to 1-20). Table 1 shows the results.

<Materials Used> 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, ferric oxide CaSO ₄ raw material: reagent primary, Gypsum dihydrate Grinding aid A: Triisopropanolamine Grinding aid B: Diethylene glycol Free lime: Synthesized by heat-treating CaO raw material at 1350 ° C for 3 hours. C ₂ F: A raw material mixed at a ratio of 2 mol of CaO raw material and 1 mol of Fe ₂ O ₃ raw material is mixed and pulverized, and then heat-treated at 1350 ° C. for 3 hours to synthesize. C ₄ AF: synthesized by mixing and pulverizing raw materials mixed in a ratio of 4 mol of CaO raw material, 1 mol of Al ₂ O ₃ raw material and 1 mol of Fe ₂ O ₃ raw material, and then heat-treating at 1350 ° C. for 3 hours. Anhydrite: Anhydrous gypsum obtained by calcining reagent grade 1 dihydrate gypsum at 1350 ° C. for 3 hours. Sand: JIS standard sand (ISO679 compliant)

<Measurement method> Length change rate: Measured according to JIS A 6202. Compressive strength: Measured according to JIS R 5201.

[0024]

[Table 1]

Table 1 shows that the mortar using the cement admixture of the present invention exhibits excellent expansion performance and strength development.

Example 2 CaO raw material, Fe ₂ O ₃ raw material and CaSO
_{The 4} raw materials were mixed with an Al ₂ O ₃ raw material as necessary, and fired at a burning temperature of 1400 ° C. using a rotary kiln to synthesize a clinker having a chemical composition as shown in Table 2. Using a ball mill, 0.05 part of the grinding aid A is used for 100 parts of clinker, and the Blaine specific surface area is 3500 cm ² /
g was prepared to prepare a cement admixture, and its performance was compared with that of a commercially available expandable material. Table 3 shows the compound composition calculated based on the chemical composition. Table 4 shows the measurement results of the length change rate.

<Materials> CaO raw material: Limestone from Aomi mine, Niigata Prefecture Al ₂ O ₃ raw material: bauxite from China Fe ₂ O ₃ raw material: rolling scale CaSO ₄ raw material: flue gas desulfurization dihydrate gypsum Expanding material A: commercially available calcium Sulfoaluminate-based expander, Blaine specific surface area 2940 cm ² / g Expander B: Commercial lime-based expander, Blaine specific surface area 36
10cm ² / g

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Table 4]

From Tables 2, 3 and 4, it can be seen that the mortar using the cement admixture of the present invention exhibits superior expansion performance as compared with a commercially available expansion material.

Example 3 The procedure of Example 2 was repeated, except that the length change rate and the compressive strength were measured by changing the type and amount of the grinding aid.
Table 5 shows the results.

<Materials used> Grinding aid C: triethanolamine Grinding aid D: 1- (bis-2-hydroxypropylamino) -2-propylmaleic acid ester

[0034]

[Table 5]

From Table 5, it can be seen that the mortar using the cement admixture of the present invention using an alkanolamine as a grinding aid exhibits excellent expansion performance and strength development.

Example 4 The cement admixture used in Experiment No. 2-1 of Example 2 was used, and the length change rate was measured by changing the amount of cement admixture used as shown in Table 6. . The results are also shown in Table 6.

[0037]

[Table 6]

Table 6 shows that as the amount of the cement admixture of the present invention increases, the mortar exhibits more excellent expansion performance.

[0039]

As described above, by using the cement admixture of the present invention, a cement composition having excellent expansion performance and good strength development can be obtained.

Continuing from the front page (72) Inventor Hiroyuki Ohashi 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Inside the Aomi Plant of Denki Kagaku Kogyo Co., Ltd. (72) Inventor Etsuro Sakai 2-5-1 Owada, Ichikawa-shi, Chiba 503 (72) Inventor Masaki 1-5-3 Tsukushino, Machida-shi, Tokyo F-term (reference) 4G012 MA00 MB23 MB33 PB03 PB11 PB12 PB20 PB32 PC12

Claims (2)

[Claims] 1. A raw material of CaO, a raw material of Fe ₂ O ₃ and CaSO
_{4 A} material obtained by blending an Al ₂ O ₃ raw material as needed with the raw material and heat-treating, free lime, calcium ferrite and / or calcium aluminoferrite, and an expanding material containing anhydrous gypsum, A cement admixture containing alkanolamines. 2. A cement composition comprising a cement and the cement admixture according to claim 1.