JP2001163651A - Grouting cement admixture and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grouting cement admixture which enables production of a grouting material having excellent flowability, effectiveness in preventing any bleeding or settlement phenomenon from being caused, good dimensional stability and further, effectiveness in inhibiting heat of hydration from being generated, and also to provide a cement composition containing the admixture. SOLUTION: This admixture comprises: an expansive material which is obtained by subjecting a CaO raw material, an Al203 raw material, an Fe2O3 raw material and a CaSO4 raw material to heat treatment and consists essentially of free lime, calcium aluminoferrite and anhydrous gypsum and has a >=4,000 cm2/g Blaine specific surface area; and a water reducing agent; wherein optionally, the admixture further additionally contains dextrin and/or a gas generating material. This cement composition comprises cement and the grouting cement admixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a cement admixture for grout, a cement admixture containing an expanding substance and a water reducing agent as main components has been proposed (JP-A-53-13650 and JP-A-53-31170). ). Cement paste, mortar and concrete (hereinafter, referred to as grout material) in which these are mixed have excellent workability and filling property, and are utilized as materials for smoothly completing grout work. The properties required for grout materials include (1) no shrinkage, (2) good fluidity and excellent retention, (3) no bleeding or settling phenomena, etc. There is a tendency to increase the number of large-capacity and mass-casting works, and (4) prevention of temperature cracks due to heat of hydration is required, and it is required to satisfy all of these required performances. However, the conventional grout material has a short time to ensure good fluidity, and in particular, causes a significant drop in fluidity during construction in the summer and causes cracks such as temperature cracks during large-capacity, large-scale casting. Sometimes occurred.

[0003] In order to reduce the economic burden, development of a cement admixture for grout, which can provide non-shrinkage even at a low admixture rate, has been awaited. In particular, as a swelling substance for obtaining non-shrinkage properties, for example, 3CaO.
There are two types: calcium sulfoaluminate based on 3Al ₂ O ₃ .CaSO ₄ , CaSO ₄ and CaO, and lime based on CaO. However, calcium-sulfoaluminate-based expanding substances cause volatilization of SOx during firing, making it difficult to obtain a predetermined mineral composition, and increasing the cost of equipment because the volatilizing SOx is collected for pollution control. There is a point. In addition, although the lime-based expanding substance can obtain a high expansion amount, it has problems such as an unstable expansion amount due to curing and the like, and a breakage due to abnormal expansion due to the influence of the control method.

[0004]

The present inventors have made various studies to solve these problems, and as a result, have found that a specific cement admixture for grout can solve the above problems. As a result, the present invention has been completed.

[0005]

That is, the present invention provides CaO
Brain 4 mainly composed of free lime, calcium aluminoferrite and anhydrous gypsum obtained by heat-treating raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and CaSO ₄ raw material
A grout cement admixture comprising a swelling substance of at least 000 cm ² / g and a water reducing agent, wherein said grout cement admixture comprises dextrin and comprises a gas foaming substance. It is a cement admixture for grout, and further a cement composition containing cement and the cement admixture for grout.

[0006]

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

The swelling substance of the present invention contains free lime, calcium aluminoferrite and anhydrous gypsum as main components, and the proportion thereof is not particularly limited. Lime is 30
It is preferably from 60 to 60 parts by weight, more preferably from 40 to 50 parts by weight. In addition, calcium alumino ferrite is 10 to 4
0 parts by weight is preferable, and 20 to 30 parts by weight is more preferable. Further, the amount of anhydrous gypsum is preferably 10 to 40 parts by weight, more preferably 20 to 30 parts by weight. If the proportion of each compound in the intumescent substance is not in the above range, good inflation performance may not be obtained.

[0008] calcium alumino ferrite of the present invention is to collectively _{CaO-Al 2 O 3 -Fe 2} O 3 compound, is not particularly limited, in general,
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.

The expanding material of the present invention comprises a CaO raw material, Al_Two
O_ThreeRaw material, Fe_TwoO_ThreeRaw materials and CaSO _FourHeat-treat the raw materials
Free lime, C_FourMainly AF and anhydrous gypsum
It is manufactured by synthesizing clinker and pulverizing it. Play
Separated lime, C_FourAF and anhydrous gypsum were synthesized separately and
The effect of the present invention can be obtained by mixing them.
Absent. CaO raw material, Al_TwoO_ThreeRaw material, Fe_TwoO_ThreeRaw materials and C
aSO_FourThe raw material is heat-treated and free lime, C_FourAF and anhydrous
Clinker made of gypsum is synthesized and crushed
As a method of confirming whether a product is manufactured, for example,
For example, if the coarse particles of the expanding material are larger than 100 μm,
Observation with a microscope etc. shows that free lime, C_FourA
Confirm that F and anhydrous gypsum are mixed
Can be determined by

The heat treatment temperature for producing the expanding material of the present invention is preferably in the range of 1100 to 1600 ° C.
The range of 0 to 1500 ° C is more preferable. If the temperature is lower than 1100 ° C., the expansion properties of the obtained expanding substance are not sufficient,
If the temperature exceeds 00 ° C., anhydrous gypsum may be decomposed.

[0011] As the CaO material, include limestone or slaked lime, etc., as the Al ₂ O ₃ raw material, include bauxite, aluminum residual ash, etc., as the Fe ₂ O ₃ raw material, copper Karami and iron powder, a commercially available Iron oxide and the like;
₄ Raw materials include dihydrate gypsum, hemihydrate gypsum, anhydrous gypsum and the like. There are impurities in these raw materials. Specific examples include SiO ₂ , MgO, Ti
O ₂ , P ₂ O ₅ , Na ₂ O, K ₂ O, etc., which are not particularly problematic as long as the object of the present invention is not substantially inhibited. ₂ is
The weight ratio is preferably 5.0% or less, more preferably 3.0% or less. If it exceeds 5.0%, good expansion performance may not be obtained.

The particle size of the expanded material of the present invention is determined by a Blaine ratio table.
4000cm in area^Two/ G or more and 4000 to 90
00cm^Two/ G is preferred and 4000 to 6000 cm^Two/
g is more preferred. Expanding substance particle size 4000cm^Two/
If it is less than g, bleeding (solid material)
Of sedimentation water is released by sedimentation or separation of
Rise) or the long-term durability deteriorates.
There is 9000cm ^Two/ G is good expansion performance
May not be obtained.

The water reducing agent of the present invention is not particularly limited and is a general term for those having a dispersing action on cement and an air entraining action, improving fluidity and increasing strength, and is usually a water reducing agent, an AE water reducing agent. Agents, high performance water reducing agents, and high performance AE water reducing agents. Among them, a high-performance AE water reducing agent having high water reducing property and excellent fluid retention is preferable. Specifically, among polyalkylallyl sulfonate condensate, melamine sulfonate condensate, lignin sulfonate, polycarboxylic acid, oxycarboxylate and aminosulfonic acid, etc. One or two or more can be used. The form of use may be powder or liquid.

The dextrin of the present invention is a general term for soluble starch obtained by subjecting starch to thermal decomposition with an acid, and is also called as roasted starch. It is used for the purpose of suppressing heat of hydration generated when a large amount of grout material is poured. The dextrin soluble in cold water is not particularly limited, but preferably has a cold water soluble content of 5 to 55%, and has a cold water soluble content of 10 to 5%.
0% is more preferable. If the amount of soluble components in cold water is less than 10%, a sufficient effect of suppressing heat of hydration may not be obtained.
%, The strength developability may deteriorate. In addition,
The term “soluble in cold water” as used in the present invention means that dextrin has a temperature of 21.
C. means the amount dissolved in distilled water at ℃, specifically, 10 g of dextrin is placed in a 200 ml flask, 150 ml of distilled water at a temperature of 21 ° C. is added, and after 1 hour, the filtrate is filtered. The dextrin obtained by distillation to dryness is shown by the weight ratio to the test dextrin.

The gas-foaming substance of the present invention is not particularly limited, and is a generic term for a substance that generates a gas when kneaded with water. It is used for the purpose of integrating with a structure. Specific examples thereof include metal powders such as aluminum powders and peroxides. The surface of the aluminum powder is easily oxidized, and the reactivity is reduced when the surface is covered with an oxide film. Therefore, the surface of the aluminum powder is treated with vegetable oil, mineral oil, stearic acid, or the like.

The use ratio of each component of the cement admixture for grout of the present invention is not particularly limited. Usually, when the cement admixture for grout comprises an expanding substance and a water reducing agent, the cement admixture for grout is usually used. Of 100 parts by weight,
The swelling substance is preferably 75 to 95 parts by weight, more preferably 80 to 90 parts by weight. If the amount is less than 75 parts by weight, material separation may occur or good dimensional stability (there is no excessive expansion that causes shrinkage or breakage of the cured product) may not be obtained. Fluidity may not be obtained. The water reducing agent is preferably 5 to 25 parts by weight, and 10
-20 parts by weight is more preferred. If the amount is less than 5 parts by weight, excellent fluidity may not be obtained. If the amount exceeds 25 parts by weight, material separation may occur or good dimensional stability may not be obtained.

When the cement admixture for grout is composed of an intumescent substance, a water reducing agent and dextrin, the intumescent substance is preferably 70 to 90 parts by weight, more preferably 75 to 85 parts by weight, per 100 parts by weight of the cement admixture. If the amount is less than 70 parts by weight, material separation may occur or good dimensional stability may not be obtained. If the amount exceeds 90 parts by weight, excellent fluidity may not be obtained. The water reducing agent is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight. If the amount is less than 5 parts by weight, excellent fluidity may not be obtained. If the amount exceeds 20 parts by weight, material separation may occur or good dimensional stability may not be obtained. Dextrin 1-15
A weight part is preferable and 3 to 10 weight parts is more preferable. 1
If the amount is less than 15 parts by weight, a sufficient effect of suppressing heat of hydration may not be obtained, and if the amount is more than 15 parts by weight, the strength expression may be deteriorated. The amount of gas foaming substance used is
Although not uniquely determined, when the grout cement admixture consists of an intumescent substance, a water reducing agent and a gas foaming substance, and when it consists of an inflating substance, a water reducing agent, dextrin and a gas foaming substance, the gas foaming substance is used. Usually, 0.005 to 0.5 part by weight is preferable, and 0.01 to 0.05 part by weight is more preferable, based on 100 parts by weight of the total of the components excluding. If the amount is less than 0.005 parts by weight, sufficient initial expansion may not be obtained, and if the amount exceeds 0.5 parts by weight, overexpansion may occur.

The amount of the cement admixture for grout of the present invention is not particularly limited, but is usually 3 to 12 parts by weight based on 100 parts by weight of cement and the cement composition comprising the cement admixture for grout. , And more preferably 5 to 9 parts by weight. If the amount is less than 3 parts by weight, good dimensional stability may not be obtained, and if the amount exceeds 12 parts by weight, long-term durability may deteriorate.

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

In the present invention, an antifoaming agent, a thickening agent, a rust inhibitor, an antifreezing agent, a shrinkage reducing agent, a polymer emulsion and a setting modifier, a cement hardened material, a clay mineral such as bentonite, a hydrotalcite, etc. It is possible to use one or more of the above anion exchangers and the like as long as the object of the present invention is not substantially inhibited.

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.

[0022]

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

Example 1 CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and CaSO
After blending the ₄ raw materials, mixing and pulverizing, 13
Heat treatment at 50 ° C. for 3 hours to synthesize expandable substances having various compositions as shown in Table 1, and a ball mill was used to obtain a Blaine specific surface area of 5%.
It was pulverized to 000 cm ² / g (measured according to JIS R 5201). The intumescent material was identified by powder X-ray diffractometry, and was confirmed to contain free lime, C ₄ AF and anhydrous gypsum. The compound composition of the intumescent substance is based on the chemical composition (JIS R 52
(Measured according to 02). A cement admixture for grout is prepared by blending 85 parts by weight of various intumescent substances and 15 parts by weight of a water reducing agent a. Cement and cement admixture for grout in 100 parts by weight of a cement composition comprising cement and grout Using 7 parts by weight of the material, water / cement composition ratio = 34%, cement composition / sand ratio =
A mortar of 1/2 was prepared, and the change with time of the consistency and the rate of change in length were measured. For comparison, a similar experiment was performed on a cement admixture produced by separately synthesizing and pulverizing free lime, C ₄ AF and anhydrous gypsum. Table 1 shows the results.

<Materials> 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 dihydrate gypsum water reducing agent a : Commercially available naphthalene sulfonate free lime: synthesized by heat-treating CaO raw material at 1350 ° C for 3 hours. 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. Cement: Commercial ordinary Portland cement Sand: Specific gravity 2.62 from Himekawa, Niigata

[0025] <Measurement Method> consistency: measuring the flow-down value in accordance with the measurement of consistency by J ₁₄ funnel of the Japan Society of Civil Engineers standard How to Display the document (JSCE-F541). Length change rate: Measured at 28 days of age according to JIS A 6202 (B).

[0026]

[Table 1]

According to Table 1, the mortar using the cement admixture for grout of the present invention is different from the mortar of the comparative example.
It shows excellent fluidity with a small J funnel falling value and little change over time, and good dimensional stability on the expansion side with a length change rate.

Example 2 The procedure of Example 1 was repeated, except that the bleeding was measured by changing the Blaine specific surface area of the expanding substance D as shown in Table 2. Table 2 shows the results.

<Measurement Method> Bleeding: Measured according to the Japan Society of Civil Engineers Standard Specification (JSCE-F533).

[0030]

[Table 2]

From Table 2, it can be seen that the specific surface area of the brane of the present invention is 40%.
By using a swelling substance of 00 cm ² / g or more,
It turns out that bleeding disappears. In addition, it has excellent fluidity with a small J-funnel falling value and little change over time, and good dimensional stability with a length change rate on the expansion side.

Example 3 The same procedure as in Example 1 was carried out except that swelling substance D was used and the type and amount of the water reducing agent were changed as shown in Table 3. Table 3 shows the results.

<Materials used> Water reducer b: Commercial melamine sulfonate water reducer C: Commercial polycarboxylic acid water reducer d: Equivalent mixture of commercial naphthalene sulfonate and commercial lignin sulfonate

[0034]

[Table 3]

From Table 3, it can be seen that by using the cement admixture for grout of the present invention, excellent flowability with a small J-funnel falling value and little change over time, and good dimensional stability with a rate of change in length on the expansion side are obtained. It turns out that it shows sex.

Example 4 A total of 10 parts consisting of 85 parts by weight of the intumescent substance D and 15 parts by weight of the water reducing agent
The procedure was performed in the same manner as in Example 1 except that the type and amount of the gas foaming substance were changed to 0 parts by weight as shown in Table 4 to prepare a cement admixture for grout, and the initial expansion coefficient was measured. Was. Table 4 shows the results.

<Materials used> Gas foaming substance a: Commercially available aluminum powder Gas foaming substance b: Reagent primary potassium persulfate Gas foaming substance c: Reagent primary sodium perborate

<Measurement method> Initial expansion rate: JSCE “Expansion concrete design and construction guidelines”, Appendix 2. Initial expansion rate measured according to the appendix "Method of measuring expansion rate of filling mortar using expanding material" indicating "Guidelines for filling mortar using expanding material". + Is the expansion side,
-Indicates a contraction side.

[0039]

[Table 4]

From Table 4, it can be seen that the use of the gas foaming material of the present invention shows that the initial expansion rate of the mortar is on the expansion side and that the mortar has an effect of preventing the settlement phenomenon. In addition, it has excellent fluidity with a small J-funnel falling value and little change over time, and good dimensional stability with a length change rate on the expansion side.

Example 5 A cement admixture for grout comprising 85 parts by weight of intumescent substance D, 15 parts by weight of water reducing agent and 0.02 parts by weight of gas foaming substance a was prepared, and a cement composition comprising cement and cement admixture for grout was prepared. Example 4 was repeated except that the amount of the cement admixture for grout in 100 parts by weight of the product was changed as shown in Table 5. Table 5 shows the results.

[0042]

[Table 5]

From Table 5, it can be seen that by using the cement admixture for grout of the present invention, the mortar has excellent flowability with a small J-funnel falling value and little change with time, and a good rate of change in length on the expansion side. It can be seen that the dimensional stability and the effect of preventing the settlement phenomenon due to the improvement of the initial expansion rate are exhibited.

Example 6 A grout cement admixture was prepared by changing the type and amount of dextrin in the total of 100 parts by weight of the swelling substance D, the water reducing agent D and the dextrin as shown in Table 6. However, the used amount of the water reducing agent was fixed at 15 parts by weight, and when the used amount of dextrin was changed, the used amount of the swelling substance was adjusted. 7 parts by weight of cement admixture for grout are used in 100 parts by weight of cement and cement admixture for grout, and a water / cement composition ratio is 34%.
A mortar having a cement composition / sand ratio of 1/2 was prepared, and a change with time in the consistency, a rate of change in length, and an increase in adiabatic temperature were measured. Table 6 shows the results.

<Materials Used> Dextrin A: cold water soluble 5% dextrin B: cold water soluble 10% dextrin C: cold water soluble 30% dextrin D: cold water soluble 50% dextrin E: cold water soluble 55%

<Measurement Method> Adiabatic Temperature Rise: A heat-insulating pot with a sample volume of 0.01 m ³ is placed in a small variable temperature chamber, and the temperature of the grout material and the temperature of the variable temperature chamber are controlled so as to be always the same. Was measured under conditions of a casting temperature of 20 ° C. using an adiabatic temperature rise measuring device manufactured by Toshiba Corporation.

[0047]

[Table 6]

From Table 6, it can be seen that the use of the dextrin of the present invention reduces the adiabatic temperature rise of the mortar and suppresses the heat of hydration. In addition, it has excellent fluidity with a small J-funnel falling value and little change over time, and good dimensional stability with a length change rate on the expansion side.

Example 7 A grout cement admixture comprising 80 parts by weight of intumescent substance D, 15 parts by weight of water reducing agent, 5 parts by weight of dextrin C and 0.02 parts by weight of gas foaming substance a was prepared. Same as Example 6 except that the amount of the cement and the grout cement admixture in 100 parts by weight of the cement composition comprising the grout cement admixture was changed as shown in Table 7 and the initial expansion rate was measured. I went to. Table 7 shows the results.

[0050]

[Table 7]

Table 7 shows that the use of the cement admixture for grout of the present invention reduced the adiabatic temperature rise of the mortar and suppressed the heat of hydration. Also, J
It shows excellent fluidity with a small funnel falling value and little change with time, good dimensional stability with a length change rate on the expansion side, and an effect of preventing a settlement phenomenon due to an improvement in the initial expansion rate.

[0052]

EFFECT OF THE INVENTION By using the cement admixture for grout and the cement composition of the present invention, it has excellent fluidity, an effect of preventing bleeding and settling, and a further excellent dimensional stability and an effect of suppressing heat of hydration. A grout material is obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C04B 28/02 C04B 28/02 C09K 17/02 C09K 17/02 P 17/10 17/10 P // C04B 103: 30 C04B 103: 30 111: 70 111: 70 C09K 103: 00 C09K 103: 00 F term (reference) 4G012 MA00 MB12 PA14 PB03 PB11 PB39 4H026 CA02 CA04 CA06 CB08 CC03

Claims (4)

[Claims] 1. A brane specific surface area of 4000 cm ² containing free lime, calcium aluminoferrite and anhydrous gypsum as main components obtained 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. / G or more of a swelling substance and a water reducing agent. 2. The cement admixture for grout according to claim 1, comprising dextrin. 3. The cement admixture for grout according to claim 1, which contains a gas foaming substance. 4. A cement composition comprising a cement and the cement admixture for grout according to any one of claims 1 to 3.