JP3171879B2 - Cement admixture and cement composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture, a cement composition, and a mortar or concrete using the same. More specifically, the present invention relates to a concrete having good flowability when concrete is poured into a formwork. After the casting, the fluidity is rapidly reduced, and the setting is accelerated, and by hardening, the cement admixture having the effect of reducing the lateral pressure applied to the concrete formwork, the cement composition, and the same are used. It relates to mortar or concrete.

[0002] The lateral pressure referred to in the present invention is a pressure at which concrete is poured into a mold and then the mold is pushed open until the concrete sets.
When there is no material separation such as breathing and the fluidity is large, the lateral pressure is large and the more the concrete is poured,
In addition, the higher the height at which the concrete is poured, the greater the lateral pressure, and if the lateral pressure is too large, it may lead to damage to the formwork.

[0003]

2. Description of the Related Art Generally, properties required for concrete include properties before hardening and properties after hardening. The properties of concrete before hardening are mainly related to ease of construction.Specifically, it is necessary to have a workable and easy-to-compact property that has appropriate softness and working time, does not separate materials such as breathing, etc. Have been.

Further, for special concrete such as underwater concrete, it is required that cement does not flow into water and alkali does not elute.

On the other hand, as properties of concrete after hardening, general physical properties such as compressive strength of concrete and various durability are required, and in the case of large structures, the heat generation temperature is low. Is also required.

[0006] That is, the required ideal concrete means that it takes a proper working time, does not have any breathing, no material separation between coarse aggregate and mortar, and does not require compaction by vibration. It can be filled in a mold with its own fluidity and has excellent physical properties and various durability. For underwater concrete and the like, there is no outflow of cement and no elution of alkali, and for large structures, concrete having a low heat of hydration is required.

As such an ideal concrete, there is a super-fluid high-performance concrete proposed by Professor Okamura of the University of Tokyo (Concrete Engineering, Vol. 26, No. 1, 1988). In addition, there is an in-water concrete using a water-insoluble admixture, which has the property that the material does not separate, that is, material inseparability and compaction unnecessary, and uses a thickener as the main component in water. Have been.

[0008] The characteristics common to these concretes include not only bleeding but also material separation of coarse aggregate and mortar, sufficient working time and superfluidity, that is, self-leveling property. Because of the fluidity of the concrete itself, it can be applied without compaction.From the viewpoint of no material separation, these concretes are unlikely to cause structural defects such as voids, and are considered to have excellent physical properties and durability. Things.

[0009] Further, on the concrete material side, compaction is not required due to imparting material non-separation and self-leveling properties, and sufficient working time is required, that is, in order to secure the characteristics of maintaining superfluidity, it is increased. It is based on the combined use of a thickener and / or a relatively large amount of a water reducing agent. In addition, fly ash or silica fume is appropriately compounded as a viscosity lowering and fluidity improving aid according to the purpose. ing.

In the construction of large structures and the like, the use of blast furnace slag powder and a super retarder to suppress heat of hydration and to prevent cold joints has been further promoted. The use of fly ash-portland cement systems or ultra-low heat cements based on dicalcium silicate clinker and the use of suitable amounts of expanders for dimensional stabilization have been implemented.

However, when a thickener and / or a water reducing agent or an ultra-low heat cement is used for ordinary concrete, the time required for the concrete to set is significantly delayed. In the case of concrete using low heat cement, it takes 9 to 12 hours or more for the first time to come even at a temperature of 20 ° C. There was a problem that the setting start time was delayed by 24 hours or more.

Further, when such concrete is poured into a large structure or the like, lateral pressure increases and the lateral pressure continues to be applied for a long time. It has become a challenge. In the case of underwater concrete, it is possible to take some measures such as forecasting the weather at the time of casting or countermeasures against increasing water.However, the casting efficiency is remarkable because the formwork can not be strengthened unlimitedly against lateral pressure. The problem of lowering remains.

In order to solve the problem of lateral pressure,
Theoretically, as long as the concrete placement is finished, the fluidity of the concrete will be lost and the setting will begin,
For this purpose, the use of setting accelerators, quick-hardening materials, quick-setting materials, etc. can be considered, but the prerequisite is that the non-separability of concrete and its superfluidity, that is, self-leveling properties, are adversely affected. There is no such thing. The most important point is that the time for maintaining the superfluidity can be arbitrarily controlled. And it is demanded that it does not affect the physical properties and durability of concrete and that it is economical. At present, such cement admixtures are strongly demanded.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by using a specific material,
Maintain the initial superfluidity for an arbitrary period of time while maintaining the unique workability of material inseparability and compaction unnecessary of mortar and concrete, and then quickly lose fluidity and promote coagulation The present invention has been completed by obtaining the knowledge that a cement admixture having the effect of reducing the lateral pressure and not adversely affecting the physical properties after curing can be provided.

[0015]

That is, the present invention provides a carbonic acid
Gnesium, and one or more components α selected from the group consisting of aluminum sulfates, and a cement admixture containing a thickener and a water reducing agent as active ingredients, component α
And one or more components β selected from the group consisting of boric acids, bentonite, limes, and gypsum,
A cement admixture containing a thickener and a water reducing agent as active ingredients, a cement composition containing cement and the cement admixture, and further, the cement composition, aggregate, and water. Mortar or concrete contained.

Hereinafter, the present invention will be described in detail.

The cement admixture according to the present invention, carbonate mug
Nesium, and one or more components α selected from the group consisting of aluminum sulfates, and a thickener and a water reducing agent as an active component, furthermore, component α,
One or more components β selected from the group consisting of boric acids, bentonite, limes, and gypsum, and a thickener and a water reducing agent as active ingredients.

In the present invention, the combined use of the component α causes the fluidity to be rapidly lost at an arbitrary time depending on the amount of addition while maintaining the superfluidity of the mortar or concrete, and then promotes the setting. It has no effect on physical properties such as strength and strength. The superfluidity also has the effect of increasing the fluidization speed. Component α of the present invention is magnesium carbonate
, And one or more components selected from the group consisting of aluminum sulfates .

The magnesium carbonates according to the present invention include magnesium carbonate, basic magnesium carbonate, dolomite and the like, and those commercially available in powder form for industrial use can be used as they are.

The aluminum sulfates according to the present invention include aluminum sulfate, alums such as potassium alum, sodium alum, and iron alum, alum stones, and calcined alum stones. Although what is commercially available in a powder state can be used as it is, alum stone or calcined alum stone obtained by calcining alum stone at about 400 to 800 ° C. has a specific surface area of 1,500 cm ² / g or more. It is preferable to use by pulverizing so that

Among the above, preferred components are magnesium carbonates, which are effective even if they are used in small amounts, followed by aluminum sulfate and calcined alumite. In particular,
A combination of magnesium carbonate and aluminum sulfate is more preferred.

The amount of the component α is determined by the type thereof, the amount of the blast furnace slag, fly ash, etc.
And thickening and / or differ by the use of water-reducing agent, on a dry solid basis, relative to the concrete 1 m ^3, 0.05
1010 kg / m ³ is preferable, and the larger the amount used, the faster the setting tends to be. Exceeds 10 kg / m ^3, blast furnace slag, fly ash, as well as at most the amount of thickeners and / or water-reducing agent coagulation is faster, it is not preferable because the time for holding the superfluid is shortened, If the amount is less than 0.05 kg / m ³ , the effect of accelerating the coagulation is small even if the amounts of the blast furnace slag and fly ash and the thickener and / or water reducing agent are small, which is not preferable.

The component β according to the present invention is one or more components selected from the group consisting of boric acids, bentonite, limes, and gypsum, and the component β alone has no effect such as accelerating coagulation. Although not shown, when used in combination with component α, it promotes the use effect of component α and also has the effect of improving fluidity. In other words, even when the initial fluidity gradually decreases with the lapse of time with the use of the component α alone, the use of the component β not only prevents the fluidity, but also increases the fluidity once and rapidly increases the fluidity. It also has the effect of promoting loss and coagulation.

The boric acids according to the present invention include boric acid, alkali metal salts, alkaline earth metal salts, ammonium salts, manganese and other metal salts of boric acid, which are commercially available for industrial use. Can be used as is.

The bentonite according to the present invention can be used for industrial purposes as it is.

The limes according to the present invention include slaked lime, quick lime, calcium carbonate and the like, and those commercially available for use can be used. The fineness of the lime is preferably 1,500 cm ² / g or more in terms of Blaine specific surface area.

The gypsums according to the present invention include dihydrate,
Various gypsums, semi-hydrated, soluble anhydrous, and insoluble or sparingly soluble anhydrous can be used. The fineness of gypsum is preferably 1,500 cm ² / g or more in terms of Blaine specific surface area.

The amount of the component β varies depending on the type thereof, but is 0.02 to 10 k per m ³ of concrete in terms of anhydrous content.
g / m ³ is preferred. Of these, the amount of boric acid used is preferably at most 0.5 kg / m ³ , the amount of bentonite, calcium carbonate, and gypsum used is 10 kg / m ³ or less, and the amount of slaked lime or quick lime used is 5 kg. / m ³ or less is preferable, and when it is outside these ranges, the time for maintaining the fluidity may be too short, or the setting may be delayed, which may impair workability.

The combination of two or more kinds of the component β is more preferable. In particular, one or more kinds selected from the group consisting of magnesium carbonate, aluminum sulfate, and calcined alum, and boric acid, bentonite, and carbonate combination with one or more kinds selected from the group consisting of calcium is not better good <br/>. Further, in consideration of economy, it is preferable to use aluminum sulfate in combination with boric acid, bentonite, and / or calcium carbonate.

In the present invention, the combined use of the component α or the components α and β with a thickening agent or a water reducing agent having an extraordinarily long setting delay time can reduce the lateral pressure and efficiently drive mortar or concrete. It is necessary in terms of installation.

Here, the thickener refers to a water-soluble polymer, such as methylcellulose, polyethylene glycol, ethylene oxide, acrylic such as polyacrylamide, etc.
And polyvinyl alcohol-based, etc., but already,
It is also possible to use what is marketed as an inseparable admixture in water. Examples of the water-immiscible admixture include, for example, cellulosic products such as "ASCA CLEAN" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), "Aqua Setter" (trade name, manufactured by Yukio Takemoto), and "Dencasta Vicon (trade name), manufactured by Denki Kagaku Kogyo Co., Ltd." A "and the like, and acrylic-based products include" Sea Better "(trade name, manufactured by Sankyo Chemical Industry Co., Ltd.) and" Aron Sea Cleat W "(trade name, manufactured by Toa Gosei Chemical Co., Ltd.). The amount of these thickeners is good in the specified amounts of the manufacturer, usually, in the case of underwater concrete that need a lot amount of thickener, concrete 1 m ³ per about 2~7kg / m ³ preferably ,
In the case of high-performance concrete or ultra-low-heat concrete, the amount is preferably about 0.01 to 2 kg, and it is preferable to appropriately change the amount of use depending on the purpose and circumstances.

Although the water reducing agent is not particularly limited,
In particular, the use of a high performance water reducing agent, a high performance AE water reducing agent, and a fluidizing agent is preferred. High performance water reducing agent, high performance AE water reducing agent,
And fluidizers are roughly divided into naphthalene-based, melamine-based,
And polycarboxylic acids. A typical example is the naphthalene-based product “Mighty 10
0 and Mighty 2000WH, Denka Grace Co., Ltd. product name "Darlex Super 100PH", and Denki Kagaku Kogyo Co., Ltd. product names "Denka FT-500" and "Denka FT-80". And "Merment F-10" manufactured by Showa Denko KK, and as the polycarboxylic acid type, "Palic FP-100S" manufactured by Fujisawa Pharmaceutical Co., Ltd. is exemplified. In addition, similar water reducing agents are commercially available from companies such as Nisso Master Builders, Zeon, Japan Sika, Kobe Materials, Sanyo Kokusaku Pulp, Takemoto Yushi, Fukui Chemical, and Daiichi Kogyo. ing. In particular, as a water reducing agent when used in combination with a thickener, it is preferable to use a melamine-based or polycarboxylic acid-based. The amount of use of these water reducing agents is sufficient in the range specified by the manufacturer.
The weight of the polycarboxylic acid is preferably 1 to 2 parts by weight.

The cement composition according to the present invention contains cement and the above-mentioned cement admixture. As the cement according to the present invention, as defined in JIS R 5201, ordinary, fast strength, super fast strength, and various Portland cements such as moderate heat, blast furnace slag, fly ash, and silica mixed with these Portland cements In addition to various mixed cements, cements containing blast furnace slag more than JIS standard can be used.Furthermore, blast furnace slag-fly ash-portland cement system optionally mixed and ultra low heat cement mainly composed of dicalcium silicate clinker Can also be used.

Further, in the present invention, it is also possible to use a cement suitably containing an expanding material, a high-strength admixture mainly composed of gypsum, and silica fume.

The mortar or concrete using the cement admixture of the present invention is obtained by appropriately mixing aggregate and mixing water with the above-mentioned cement composition. The composition varies depending on the target structure such as design strength, and is not particularly limited, but the unit cement amount is 300 kg / m ³ or more,
The water / cement ratio is preferably 60% or less, and the slump flow as an index of fluidity is preferably 400 mm or more.

Here, the slump flow refers to the diameter of the spread when concrete is packed in a slump cone by a conventional method and the cone is pulled out in the manner of slump measurement.
Further, the mortar can be used as a pre-packed, grout, and self-leveling material for floors, and its composition is not particularly limited as long as the material non-separability and superfluidity are not impaired.

In the present invention, the method of using the cement admixture is not particularly limited. However, when kneading concrete in a powder state, it may be put into a mixer together with other materials, or may be mixed. It may be added when dissolving or suspending in the whole or a part of the mixing water and kneading the concrete, and the dissolved or suspended substance may be put into an agitator truck for transporting concrete.

[0038]

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

[0039] Example 1 Water 150 kg / m ^3, cement 192 kg / m ^3, the slag 128 kg / m ^3, fine aggregates 858kg / m ^3, coarse aggregate 1,015kg / m ^3, water reducing agent Lee 9.6 kg / m ^3, and a unit amount of thickener two 1.0kg / m ^3, Gmax15mm, water / powder ratio
47%, air amount 2 ± 1%, fine aggregate ratio 48%, and slump flow 500-600mm. As shown in Table 1, the type and addition amount of component α were changed, Using a forced kneading mixer, 40 liters of concrete was kneaded. Using this concrete, the time-dependent change in slump flow, the time required for spreading the concrete immediately after kneading (time), the time until the onset of setting, and the 28-day compressive strength of a φ10 × 20 cm specimen were measured. The results are also shown in Table 1.

The change in the slump flow with the lapse of time was repeatedly measured with a scoop when the measurement time had elapsed while the concrete was kept still. The compressive strength was removed from the mold 3 days after the aging to obtain a standard curing.

<Materials used> Cement: Ordinary Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Specific gravity 3.16 Slag: Slag manufactured by Kawatetsu Riverament Co., Ltd., Blaine specific surface area 4,500 cm ² / g, specific gravity 2.75 Fine aggregate: Himekawa river sand, Niigata prefecture, specific gravity 2.62 Coarse aggregate: crushed stone from Himekawa, Niigata Prefecture, specific gravity 2.64 Water reducing agent a: High performance water reducing agent, Denka FT-500 (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.), naphthalene thickener d: Sankyo Chemical Industries Product name “Sea Better”, main component acrylic component αA: magnesium carbonate, industrial 〃 B: basic magnesium carbonate, reagent 〃 C: aluminum sulfate, reagent Ｄ D: potassium alum, reagent Ｅ E: calcined alum stone, Hiroshima Alumite from Katsumitsuyama prefecture is baked at 600 ° C and pulverized to a Blaine specific surface area of 2,000cm ² / g.

[0042]

[Table 1]

As is apparent from Table 1, it is possible to rapidly reduce the flow and promote the setting while maintaining the slump flow for an arbitrary time by using the component α. Then, it is recognized that by increasing the amount of the component α, the time during which the flow is maintained is shortened, and the coagulation can be further promoted.

[0044] Example 2 water 225 kg / m ^3, cement 450 kg / m ^3, fine aggregates 642kg / m ^3, coarse aggregate 970 kg / m ^3, water reducing agent b 4.5 kg / m ^3, and a thickener Ho 3 kg / m ³
The water / powder ratio is 50% and the fine aggregate ratio is 40%,
As shown in Table 2, the same procedure as in Example 1 was carried out except that the type of component α and the amount added were changed. The results are also shown in Table 2.

<Materials> Water reducer b: High-performance water reducer, trade name "Melment", a main component of Showa Denko melamine-based thickener E: Shin-Etsu Chemical Co., Ltd. trade name "ASCAR Clean", a main component of methylcellulose

[0046]

[Table 2]

[0047] Example 3 Water 159 kg / m ^3, cement 155 kg / m ^3, slag 171kg / m ^3, fly ash 202 kg / m ^3, the expansion member 10 kg / m ^3, fine aggregates 733Kg /
m ^3, coarse aggregate 903kg / m ^3, water reducing agent C 6 kg / m ^3, and a thickener ho
A unit amount of 0.02 kg / m ^3, the water / powder ratio 30%, fine aggregate ratio 4
The procedure was performed in the same manner as in Example 1 except that the content and the amount of the component α were changed as shown in Table 3 to 5%. The results are also shown in Table 3.

<Materials used> Fly ash: Fly ash manufactured by Joban Power Generation Co., Ltd., specific gravity 2.40 Expanding material: Denka CSA # 20 manufactured by Denki Kagaku Kogyo Co., Ltd. Water reducing agent C: High-performance AE water reducing agent, manufactured by Kao Corporation Name "Mighty 2000WH" Main component: naphthalene

[0049]

[Table 3]

Example 4 Magnesium carbonate or aluminum sulfate of component α 0.5 kg /
Example 3 was carried out in the same manner as in Example 1 except that the component α was used in combination with m ³ as shown in Table 4. The results are shown in Table 4.

[0051]

[Table 4]

As is apparent from Table 4, the combination of two or more kinds of the component α can promote the setting more effectively.

Example 5 As shown in Table 5, the same procedure as in Example 1 was carried out except that the components α and β were used. The results are also shown in Table 5.

<Materials Used> Component βa: boric acid, industrial grade 〃b: bentonite, trade name “Premium Gel” manufactured by Kanto Bentonite Mining Co., Ltd. 〃c: slaked lime and limestone were calcined in a UCL furnace, sprinkled with water and digested Adjusted to a specific surface area of 5,000 cm ² / g. 〃D: Calcined lime and limestone are fired in a UCL furnace to adjust the brane specific surface area to 2,500 cm ² / g. 〃E: Calcium carbonate and limestone are adjusted to a Blaine specific surface area of 3,000 cm ² / g. 〃F: Hydrofluoric acid-producing gypsum and insoluble anhydrous gypsum were adjusted to a Blaine specific surface area of 3,000 cm ² / g.

[0055]

[Table 5]

As is clear from Table 5, the components α and β
It has been shown that the use of a combination promotes coagulation and once improves the fluidity.

Example 6 As shown in Table 6, the same procedure as in Example 5 was carried out except that the component α and two or more types of the components β were used. Table 6 shows the results
It is described together.

[0058]

[Table 6]

As is clear from Table 6, the combined use of component α and two or more components β promotes coagulation more effectively in a small amount, and the combined use of boric acid, bentonite, and calcium carbonate is particularly effective. preferable.

[0060]

As described above in detail in the embodiments,
By using the cement admixture of the present invention, without affecting physical properties such as superfluidity and compressive strength, it accelerates the onset of setting, is effective in reducing lateral pressure, etc., and increases the casting efficiency. It is possible. The time and coagulation for maintaining the superfluidity can be arbitrarily adjusted by the amount used. Flop <br/> Repertoire Kkudo, grout, and setting time while securing any time material nondisjunction of the superfluid also freely be controlled with respect to the mortar for self-leveling, before curing drying shrinkage, etc. It is effective against subsidence and cracking of plastic. It produces effects such as:

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI C04B 28/02 C04B 28/02 // C04B 103: 12 103: 30 103: 44 (56) References JP-A-57-200253 ( JP, A) JP-A-64-61339 (JP, A) JP-A-61-122146 (JP, A) JP-A-62-52158 (JP, A) JP-A-52-98730 (JP, A) 59-57939 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 22/10 C04B 22/06 C04B 22/08 C04B 22/14 C04B 28/02

Claims (4)

(57) [Claims] 1. Magnesium carbonate and aluminum sulfate
Cement admixture of the one or more components α selected from the group consisting of um such, as an active ingredient a thickener and water reducing agent. 2. The component α according to claim 1, one or more components β selected from the group consisting of boric acids, bentonite, limes, and gypsum, and a thickener and a water reducing agent. Cement admixture as an active ingredient. 3. A cement composition comprising a cement and the cement admixture according to claim 1 or 2. 4. The cement composition according to claim 3, an aggregate,
And concrete containing water and water.