JPH07206494A - Cement admixture and cement composition - Google Patents

Abstract

PURPOSE:To obtain a cement admixture to which high expendability is imparted without degrading strength developability by compounding an expanded material obtd. by heat treating a mixture composed of a CaO raw material, Al2O3 raw material and CaSO4 raw material and anhydrous gypsum. CONSTITUTION:This cement admixture contains the expanded material which consists of the ore formed by heat treating the mixture contg. the CaO raw material, the Al2O3 raw material and the CaSO4 raw material and contg. the CaO, the A2O3 and the CaSO4 as its essential components and in which the component ratios are the molar ratio of the CaO/Al2O3 is 7.5 to 18 and the molar ratio of the CaSO4/Al2O3 is 1.6 to 4 and the anhydrous gypsum. Further, amorphous calcium aluminate in addition to the compsn. described above may be incorporated into the admixture. The CaO raw material of the expanded material is exemplified by limestone, slaked lime, etc., and the Al2O3 raw material by bauxite, residual ashes of aluminum, etc., and the CaSO4 raw material by anhydrous gypsum, hemihydrate gypsum, gypsum dihydrate, etc. The calcination tap. is preferably about 1100 to 1600 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD 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]

2. Description of the Related Art Cement is a widely used material because it can produce large structures at low cost, but it has the problem of shrinking, and many cements are used to compensate for this shrinkage. Cement admixtures have been proposed (JP-A-53-13650, JP-A-53-31170, etc.). These cement admixtures impart expandability and are excellent materials for supplementing shrinkage of cement.

However, the hardened material using cement has a problem that the strength developing property decreases as it receives a large expansion force without receiving any restraining force. There has been an increasing demand for cement admixtures that can impart great expandability without being treated.

The present inventor has made diligent efforts to solve these problems, and as a result, by using a cement admixture in which a specific expansive substance and anhydrous gypsum are combined,
Furthermore, they have found that the problem can be solved by using an amorphous calcium aluminate together, and have completed the present invention.

[0005]

Means for Solving the Problems That is, the present invention is an expansive substance produced by heat-treating a mixture containing a CaO raw material, an Al ₂ O ₃ raw material, and a CaSO ₄ raw material, and CaO, Al ₂ O ₃ , And CaSO ₄
Is used as an active ingredient, and the component ratio in the mineral is CaO / Al ₂ O ₃ molar ratio of 7.5 to 18, CaSO ₄ / Al ₂ O ₃
A cement admixture containing an expanding substance having a molar ratio of 1.6 to 4 and anhydrous gypsum, which is a cement admixture containing the expanding substance, amorphous calcium aluminate and anhydrous gypsum. And a cement composition containing the cement admixture and cement.

The present invention will be described in more detail below.

The raw material of the expansive substance according to the present invention can be arbitrarily selected depending on the purity and cost and is not particularly limited. For example, the CaO raw material is CaCO ₃ such as limestone or slaked lime. Quality and Ca (OH) ₂ quality,
Examples of the Al ₂ O ₃ raw material include bauxite and aluminum residual ash, and examples of the CaSO ₄ raw material include anhydrous gypsum, hemi-water gypsum, and dihydrate gypsum. The mixing of impurities such as SiO ₂ , Fe ₂ O ₃ , CaF ₂ , MgO, and TiO ₂ existing in the raw material is not particularly limited as long as it does not substantially impair the object of the present invention.

The compounding ratio of various raw materials in the present invention is such that, as the chemical composition of the expanding substance as a product, the CaO / Al ₂ O ₃ molar ratio is 7.5 to 18, and the CaSO ₄ / Al ₂ O ₃ molar ratio is 1.6 to. It is necessary to adjust the ratio to be 4, and the CaO / Al ₂ O ₃ molar ratio is 8-12.
Is preferable, and the CaSO ₄ / Al ₂ O ₃ molar ratio is preferably 2 to 3.
If the CaO / Al ₂ O ₃ molar ratio is less than 7.5, it may not be possible to obtain sufficient expandability when used in mixed cement, and if it is used in excess of 18, expansion failure may occur. Further, if the CaSO ₄ / Al ₂ O ₃ molar ratio is less than 1.6, sufficient expandability may not be obtained, and if it exceeds 4, the timing of expansion may be delayed and expansion fracture may occur.

In the present invention, the desulfurization temperature of gypsum varies greatly depending on the blending ratio of the raw material mixture and the content of impurities. Therefore, the firing temperature at the time of firing is not particularly limited, but normally, The temperature is preferably about 1,100 to 1,600 ° C. The method of mixing the raw materials is not particularly limited, and an ordinary method can be used. The heat treatment method for producing the expansive substance is not particularly limited, and for example,
Any method such as firing with a rotary kiln or melting with an electric furnace is possible.

The particle size of the expansion material is not particularly limited, but a Blaine value of 1,500 to 8,000 cm ² / g is preferable.
If it is less than 1,500 cm ² / g, strength development tends to deteriorate,
If it exceeds 8,000 cm ² / g, the expandability may not be fully exhibited.

The amount of the expansive substance used is 5 in 100 parts by weight of the cement admixture consisting of the expansive substance and anhydrous gypsum described below.
0 to 90 parts by weight is preferable, and 60 to 80 parts by weight is more preferable. If it is less than 50 parts by weight, the expandability may decrease,
If it exceeds the weight part, the strength development effect may not be sufficiently obtained. Further, when using the below-mentioned amorphous calcium aluminate in combination, in the cement admixture 100 parts by weight of an expansive substance, amorphous calcium aluminate, and anhydrous gypsum, preferably 50 to 80 parts by weight, 55 ˜65 parts by weight is more preferred. If it is less than 50 parts by weight, the swelling property may decrease, and if it exceeds 80 parts by weight, the effect of developing strength may not be sufficiently obtained.

[0012] The anhydrous gypsum according to the present invention is not particularly limited, and in addition to natural anhydrous gypsum produced naturally, it is generated by heat-treating semi-water gypsum or dihydrate gypsum or as an industrial by-product. Although it is possible to use such substances, it is preferable to use anhydrous gypsum having a high dissolution rate of 300 mg / l · min or more. Here, the dissolution rate of anhydrous gypsum is 50% in 1 liter of water at 20 ° C.
g of anhydrous gypsum was added, the mixture was stirred for 1 minute at 60 rpm, and the sulfate ion in the supernatant was analyzed by ion chromatography to show the value converted into the amount of CaSO ₄ .

The particle size of anhydrous gypsum is not particularly limited, but the Blaine value is preferably 2,500 to 9,000 cm ² / g. If it is less than 2,500 cm ² / g, long-term durability may be deteriorated, and if it exceeds 9,000 cm ² / g, expandability may not be sufficiently exhibited.

The amount of anhydrous gypsum used is 10 to 50 in 100 parts by weight of the cement admixture consisting of the expansive substance and anhydrous gypsum.
Weight part is preferable, and 20-40 weight part is more preferable. If it is less than 10 parts by weight, sufficient strength-producing effect may not be obtained, and if it exceeds 50 parts by weight, expandability may be insufficient. When the amorphous calcium aluminate is used in combination, 10 parts by weight of the cement admixture consisting of the expansive substance, the amorphous calcium aluminate, and anhydrous gypsum are used.
-40 parts by weight is preferable, and 20-30 parts by weight is more preferable.
If it is less than 10 parts by weight, sufficient strength-producing effect may not be obtained, and if it exceeds 40 parts by weight, expandability may be insufficient.

Amorphous calcium aluminum according to the present invention
It is preferable that the CaO content is 35 to 45% by weight. If the CaO content is less than 35% by weight, the expandability and strength development may be insufficient, and if it exceeds 45% by weight, the fluidity may decrease and the workability may deteriorate. Amorphous calcium aluminate is obtained by melting a CaO raw material and an Al ₂ O ₃ raw material and quenching the resulting clinker. The grain size of the amorphous calcium aluminate is not particularly limited, but the grain value is preferably 1,500 to 6,000 cm ² / g. If it is less than 1,500 cm ² / g, sufficient expandability may not be obtained, and if it exceeds 6,000 cm ² / g, workability may deteriorate.

The amount of the amorphous calcium aluminate used is 5 to 2 in 100 parts by weight of the cement admixture consisting of the expansive substance, the amorphous calcium aluminate, and anhydrous gypsum.
5 parts by weight is preferable, and 10 to 20 parts by weight is more preferable. 5
If it is less than part by weight, it may be difficult to obtain the strength development effect,
If the amount exceeds 25 parts by weight, the expandability may be reduced, or the fluidity of a cement kneaded mixture of cement, a cement admixture, water and the like may be reduced, resulting in poor workability.

The particle size of the cement admixture of the present invention depends on the purpose and application to be used and is not particularly limited, but it is usually used in a range of 1,500 to 8,000 cm ² / g in terms of brain value. It is preferable. If it is less than 1,500 cm ² / g, the strength development may be adversely affected, and if it exceeds 8,000 cm ² / g, the expandability may not be sufficiently exhibited.

The amount of the cement admixture of the present invention to be used varies depending on the purpose of use, but when the cement admixture comprises an expansive substance and anhydrous gypsum, it is 3 per 100 parts by weight of the total amount of the cement and the cement admixture. -15 parts by weight is preferable, and 5-12 parts by weight is more preferable. If it is less than 3 parts by weight, the expandability is not sufficient, and if it exceeds 15 parts by weight, abnormal expansion may occur. When the cement admixture is composed of expansive substances, amorphous calcium aluminate, and anhydrous gypsum, it is preferably 3 to 20 parts by weight, more preferably 5 to 15 parts by weight. If it is less than 3 parts by weight, the expandability is not sufficient,
If it is used in excess of the weight part, abnormal expansion may occur.

As the cement according to the present invention, various portland cements such as normal, early strength, super early strength, and moderate heat, various mixed cements obtained by mixing these portland cements with pozzolan substances such as blast furnace slag and silica, and Alumina cement etc. are mentioned. The cement admixture of the present invention is particularly effective when used in combination with mixed cement.

In the present invention, in addition to cement and a cement admixture, a coagulation modifier, a water reducing agent, a high-performance water reducing agent, an AE agent, A
E water reducing agent, high performance AE water reducing agent, thickening agent, aggregate such as sand and gravel, cement rapid hardening material, rust inhibitor, antifreezing agent, polymer emulsion, clay mineral such as bentonite, zeolite, hydrotalcite, And one or more of ion exchangers such as hydrocalumite, inorganic sulfates such as aluminum sulfate and sodium sulfate, inorganic phosphates, and boric acid do not substantially inhibit the object of the present invention. It can be used in combination within a range.

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 a part or all of them may be mixed in advance. . As the mixing device, any existing stirring device can be used, for example, a tilting barrel mixer, an omni mixer, a V-type mixer, a Henschel mixer, a Nauta mixer, or the like can be used.

The method for curing the concrete of the present invention is not particularly limited, and any conventional curing method such as normal temperature / normal pressure curing, steam curing, high temperature / high pressure steam curing, and pressure curing is performed. However, the effect of the present invention is more remarkable when steam curing is performed. When performing steam curing, it is more preferable to perform pre-curing for about 3 to 8 hours at room temperature and atmospheric pressure.

[0023]

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

Example 1 Limestone powder was used as a CaO raw material, aluminum residual ash was used as an Al ₂ O ₃ raw material, and natural anhydrous gypsum was used as a CaSO ₄ raw material. −
The resulting clinker was pulverized by calcination using a tarry kiln and adjusted to a blasting value of 3,000 ± 200 cm ² / g to obtain an expanded material. The unit amount is 500 kg / m ^{3 of} cement and 96 coarse aggregate.
0 kg / m ^3, fine aggregates 713kg / m ^3, and concrete formulation of water 200 kg / m ³ - Doo, a cement admixture composed of 70 parts by weight of expanded material are shown in Table 1 and anhydrous gypsum 30 parts by weight of cement And 7 parts by weight for 100 parts by weight of cement admixture,
A concrete kneaded product was prepared to prepare a test piece of φ100 mm and L200 mm. After placing the prepared specimen for 4 hours,
The temperature was raised at a heating rate of 16 ° C / h, steam curing was performed at 65 ° C for 5 hours, and the mixture was naturally cooled. After that, the compressive strength of each material was measured. Further, the expansion coefficient was measured according to the JIS A 6202B method. After the 1-day age measurement, underwater curing was performed. The results are also shown in Table 1.

<Materials used> CaO raw material: Limestone powder from the Omi mine of Denki Kagaku Kogyo,
4,230cm ² / g Al ₂ O ₃ Raw material: Aluminum residual ash, Nippon Kasei Kako Co., Ltd. CaSO ₄ raw material: Natural anhydrous gypsum, Blaine value 5,830 cm ² /
g Expansion material A: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 4: 1: 2.5 Expansion material B: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 7.5: 1: 2.5 Expansion material C: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 8: 1: 2.5 Expansion material D: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 10: 1: 2.5 Expansion material E: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 12: 1: 2.5 Swelling material F: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 18: 1: 2.5 Swelling material G: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 20: 1: 2.5 Swelling material H ₂ : CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 10: 1: 1 Expansion material I: CaO: Al ₂ O ₃ : CaSO ₄ molar ratio = 10: 1: 1.6 Expansion material J: CaO: Al ₂ O ₃ : CaSO ₄ Molar ratio = 10: 1: 2 Swelling substance K: CaO: Al ₂ O ₃ : CaSO ₄ Molar ratio = 10: 1: 3 Swelling substance L: CaO: Al ₂ O ₃ : CaSO ₄ Molar ratio = 10: 1: 4 expansion material _{M: CaO: Al 2 O 3} : CaSO 4 molar ratio = 10: 1: 5 anhydrous gypsum: natural gypsum, solubility 352 mg / l · min cement alpha: Denki Kagaku Kogyo Co., Ltd. ordinary portland Doo Coarse aggregate: Niigata Prefecture Himekawa production, Gmax = 15mm, specific gravity 2.67 fine aggregate: Niigata Prefecture Himekawa production, specific gravity 2.63 water: tap water The composition of the expansion material, in accordance with JIS R 5202, CaO, A
The amounts of l ₂ O ₃ and SO ₃ were analyzed, and the amount of SO ₃ was converted to CaSO ₄ for determination.

[0026]

[Table 1]

Example 2 Using expansive substance D, the sum of cement and cement admixture
Example 1 was repeated except that the compounding amount of the cement admixture with respect to 100 parts by weight was changed as shown in Table 2.
The results are also shown in Table 2.

[0028]

[Table 2]

[0029] The blast furnace cement is used as in Example 3 Cement, amount units, each cement 500 kg / m ^3, coarse aggregate 953kg / m ^3, fine aggregates 708kg / m ^3, and concrete formulation of water 193 kg / m ³ Was performed in the same manner as in Example 1 except that 1 part by weight of the water reducing agent was added to 100 parts by weight of the cement and the cement admixture in total. The results are shown in Table 3.

<Materials used> Cement β: Blast furnace cement type B water reducing agent manufactured by Denki Kagaku Kogyo Co., Ltd .: Denka FT-500G manufactured by Denki Kagaku Kogyo Co., Ltd. Main component naphthalenesulfonic acid formalin condensate

[0031]

[Table 3]

Example 4 Example 3 was repeated except that the expanding substance D was used and the amount of anhydrous gypsum in 100 parts by weight of the cement admixture was changed as shown in Table 4. The results are also shown in Table 4.

[0033]

[Table 4]

Example 5 A cement admixture consisting of 60 parts by weight of the expansive substance shown in Table 5, 15 parts by weight of amorphous calcium aluminate (A-CA), and 25 parts by weight of anhydrous gypsum was added to the cement and the cement admixture. Was carried out in the same manner as in Example 1 except that 10 parts by weight was added to 100 parts by weight in total. The results are shown in Table 5.

<Materials used> A-CAi: A clinker obtained by melting a clinker obtained by melting a mixture of calcium carbonate of a first-grade reagent and aluminum oxide in a molar ratio of 10: 8 at 1,650 ° C. and quenching. Brain value
It was set to 3,410 cm ² / g. CaO content 40%

[0036]

[Table 5]

Example 6 The total amount of cement and cement admixture using the expansive substance D
Example 5 was carried out in the same manner as in Example 5 except that the compounding amount of the cement admixture with respect to 100 parts by weight was changed. The results are shown in Table 6.

[0038]

[Table 6]

Example 7 Example 5 except that cement β was used as the cement.
I went the same way. The results are shown in Table 7.

[0040]

[Table 7]

Example 8 Using the expanding substance D, the amount of anhydrous gypsum in 100 parts by weight of the cement admixture was changed, and the amounts of the expanding substance and A-CA were increased / decreased in equal amounts to keep the amount of the cement admixture constant. The same procedure as in Example 7 was carried out except that The results are shown in Table 8.

[0042]

[Table 8]

Example 9 Using the expanding substance D, A in 100 parts by weight of the cement admixture
-Example 7 was repeated except that the type and amount of CA was changed, and the amounts of the expansive substance and anhydrous gypsum were increased / decreased in equal amounts to make the amount of the cement admixture constant. The results are shown in Table 9.

<Materials used> A-CA: A clinker obtained by crushing a clinker obtained by melting a mixture of calcium carbonate of a first-grade reagent and aluminum oxide in a molar ratio of 10:10 at 1,650 ° C. and quenching. Brain value
It was set to 3,150 cm ² / g. CaO content 35% A-CA Ha: A mixture of calcium carbonate of the reagent first grade and aluminum oxide having a molar ratio of 10: 7 was melted at 1,650 ° C. and rapidly cooled. Value
It was set to 3,090 cm ² / g. CaO content 44%

[0045]

[Table 9]

[0046]

EFFECTS OF THE INVENTION By using the cement admixture of the present invention, in particular, an expansive property is imparted to the mixed cement, and a cement composition exhibiting high strength development is obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C04B 22:14 DB 22:08) Z 103: 60

Claims (3)

[Claims] 1. An expansive substance produced by heat-treating a mixture containing a CaO raw material, an Al ₂ O ₃ raw material, and a CaSO ₄ raw material.
O, Al ₂ O ₃ , and CaSO ₄ consisting of minerals with active ingredients,
Moreover, the CaO / Al ₂ O ₃ molar ratio of the minerals is 7.5.
Cement admixture containing an expansion substance having a CaSO ₄ / Al ₂ O ₃ molar ratio of 1.6 to ₄ and anhydrous gypsum. 2. An expansive substance produced by heat-treating a mixture containing a CaO raw material, an Al ₂ O ₃ raw material, and a CaSO ₄ raw material.
O, Al ₂ O ₃ , and CaSO ₄ consisting of minerals with active ingredients,
Moreover, the CaO / Al ₂ O ₃ molar ratio of the minerals is 7.5.
Cement admixture containing an expansive substance having a CaSO ₄ / Al ₂ O ₃ molar ratio of 1.6 to ₄ and amorphous calcium aluminate and anhydrous gypsum. 3. A cement composition containing cement and the cement admixture according to claim 1 or 2.