JP2817920B2 - Cement admixture - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cement admixture, in particular, to reduce viscosity,
The present invention relates to a cement admixture with good workability and high strength.

[Conventional technology and its problems]

Conventionally, high-performance water reducing agents are generally used in ready-mixed concrete plants, etc., compared with ordinary water reducing agents such as lignin sulfonates and polyols. Low water resistance, high water reduction rate,
It has good characteristics that high strength concrete can be easily manufactured. However, on the other hand, concrete to which a high-performance water reducing agent is added has the following characteristics.

(2) The standard curing (curing in water at 20 ° C) provides the design strength, but the air-dry curing reduces the strength and does not provide the design strength.

(3) Slump drop is remarkably large.

For example, there are the following problems in construction.

That is, the fact that the viscosity is strong means that if the construction site is inclined, the concrete is dripped or slipped down, and the construction cannot be performed. Furthermore, since self-fluidity occurs in concrete, slump design cannot be performed.

The fact that the strength is reduced by air-dry curing means that actual civil engineering and architectural structures cannot undergo underwater curing or sufficient wet curing at all and tend to be air-dried curing, and the design strength of the frame itself cannot be obtained. And cannot be used for design. In addition, the fact that the slump drop is extremely large means that a general-purpose system for producing concrete in a ready-mixed concrete plant and performing construction by transporting an agitator car cannot be used at all, and thus lacks versatility. In fact, ready-mixed concrete to which only a high-performance water reducing agent is added has not been widely used.

On the other hand, a technology that can achieve sufficient design strength without reducing strength even in air-dry curing and can prevent slump drop is achieved by using gypsum and citric acid and its salts, alkali metal carbonates, and siliceous substances in combination. (JP-A-58-167460).

However, these methods do not solve the problem caused by the fact that concrete using a high-performance water reducing agent has a high viscosity.

On the other hand, in concrete product factories, the time to process concrete is extremely short, so slump drops with high-performance water reducing agents are not a major problem and are widespread, but the viscosity is, for example, as large as the capacity of the concrete mixer. There are problems such as inability to knead concrete, no concrete from the hopper, and ironing, and the present invention also solves these problems.

The present inventors have eliminated the viscosity of concrete to which a high-performance water reducing agent has been added, and further studied for the purpose of obtaining high strength while reducing the viscosity and reducing or preventing slump drop. The inventor has found that the above problem can be solved by blending the composition, thereby completing the present invention.

[Means for solving the problem]

That is, the present invention provides (1) a cement admixture containing a high-performance water reducing agent, a main component of vermiculite having a mesh size of 400 mesh or less, gypsum and / or an active siliceous substance. A cement admixture containing inorganic salts and / or organic acids.

 Hereinafter, the present invention will be described in detail.

The high-performance water reducing agent of the present invention generally indicates a polyalkylallyl sulfonate type, a melamine formalin resin sulfonate type, and the like, and a commercially available high-performance water reducing agent containing any one of these as a main component However, a water-reducing agent having properties such as strong viscosity and non-breathing can be used as the high-performance water-reducing agent of the present invention (hereinafter, referred to as the present water-reducing agent) even if the above-mentioned components are not the main component. .

Examples of the polyalkylallyl sulfonate include a naphthalenesulfonic acid formalin condensate, a methylnaphthalenesulfonic acid formalin condensate, and an anthracenesulfonic acid formalin condensate. These commercial products include Kao Corporation's trade names “Mighty 100” and “Mighty 15
"0", "Mighty 2000", Daiichi Kogyo Seiyaku Co., Ltd. product names "Cell Flow 110P", "Cell Flow CA155P", etc., Takemoto Yushi Co., Ltd. product name "Paul Fine 510N", etc. "Sunflow PS", "Sunflow PSR120", etc.
−500 ”. Examples of the melamine formalin resin sulfonate include Showa Denko KK “Melment F-10” and “Melment-F-20”, and Nisso Master Builders KK “NL-4000”. No.

These water reducing agents are added in an amount of 0.25 to 5 parts by weight in terms of solid content based on 100 parts by weight of cement. If the amount is less than 0.25 parts by weight, the original effect such as water reduction as a water reducing agent cannot be expected, and if it exceeds 5 parts by weight, the improvement of the water reduction rate cannot be expected, and the economical efficiency is deteriorated. A preferable amount is 0.35 to 3 parts by weight, and a more preferable amount is 0.45 to 2 parts by weight.

Vermiculite is obtained by firing vermiculite ore (called hillite in Japan) at about 1,000 ° C., and its use amount is 0.1 to 10 parts by weight per 100 parts by weight of cement.

If the amount is less than 0.1 part by weight, the effect of reducing the viscosity cannot be expected. If the amount exceeds 10 parts by weight, the strength is greatly reduced due to a remarkable increase in the unit water amount, and the slump drop is also not preferable.

A preferred range is 0.4-5 parts by weight, and a more preferred range is 1-3 parts by weight.

Gypsum is hard gypsum (II type anhydrous gypsum),
Soluble anhydrous gypsum (type III anhydrous gypsum), hemihydrate gypsum and dihydrate gypsum are used, and one or more of these are usually used, but they react with aluminate in cement and produce hydrated ettringite. There are no restrictions on the types and amounts of impurities that are simply contained industrially as long as

The amount of gypsum used is at most 15 parts by weight in terms of anhydride relative to 100 parts by weight of cement, preferably 1 to 13 parts by weight.
Parts by weight, more preferably 2 to 10 parts by weight. The appropriate amount of gypsum for cement strength is determined mainly by the curing temperature, and the higher the temperature, the more the maximum strength is reached.The maximum amount of gypsum used for steam curing at 60-80 ° C is 10-13 parts by weight, with 15 Even if it is added in excess of parts by weight, elongation in strength cannot be expected, but rather, it will be slightly reduced, which is not preferable. At about 20 ° C., the peak is at 4 to 6 parts by weight, and at lower temperatures, the peak is at 3 to 5 parts by weight, and at less than 1 part by weight, the effect of addition is small even at low temperatures.

Gypsum has a fineness of 2,000 cm ² / g or more (Brain method,
Porosity 0.5), preferably 3,000 cm ² / g or more, more preferably 4,000 cm ² / g or more.

Activated siliceous substances are silica fume, aerosil,
Shows ultrafine powders such as blast furnace slag and fly ash.

The silica fume is a dust by-produced when producing an electric furnace a silicon alloy or metal silicon, and Aerosil, those obtained by the chlorosilane is hydrolyzed, either be a SiO ₂ of micronised powder It is amorphous and rich in pozzolanic activity.

These are those which produce a high-strength cured product by a pozzolanic reaction, and which, when used in combination with the vermiculite of the present invention, eliminate viscosity and do not lose their strength-developing ability.

These are used in an amount of 1 to 25 with respect to 100 parts by weight of cement.
If the amount is less than 1 part by weight, the effect of use is small, and if the amount exceeds 25 parts by weight, the elongation of the strength becomes small, which is not preferable because it is uneconomical.

The preferred range is 2 to 15 parts by weight, and when used in combination with gypsum, even a small amount increases the strength effect.

Further, the inorganic salts of alkali metals (hereinafter referred to as inorganic salts) according to the present invention include carbonates, bicarbonates, silicates, aluminates, and Na · K of alkali metals such as Li · Na · K.
Alum, aluminum sulfate, magnesium sulfate and the like.

Inorganic salts promote the effect of reducing the viscosity of vermiculite and enhance the strength, but especially the carbonates and bicarbonates of alkali metals are effective in reducing the slump drop when used in combination with oxypolycarboxylic acids. It is preferable because it exhibits the following.

The amount of inorganic salts used is at most 1.0 part by weight (anhydrous equivalent) per 100 parts by weight of cement. If the amount used exceeds this, the effect of use will not be further improved, or false setting or rapid setting will occur. Some components are produced and are not preferred. The most preferred range is from 0.1 to 0.5 parts by weight.

Organic acids are soluble organic acids having a COOH group or an OH group and a COOH group at the same time, or a metal salt thereof, and those obtained by adding an alkyl group or an aryl group to these derivatives or unsaturated organic acids, And those obtained by condensation or copolymerization based on these.

The lowest and generally easily available commercially available carboxylic acids are oxalic acid, maleic acid, fumaric acid, malonic acid, succinic acid, glutaric acid, adipic acid and the like or metal salts thereof, and oxymonocarboxylic acid salts are , Lactic acid,
Heptonic acid, gluconic acid, glycolic acid and the like or metal salts thereof, and the oxypolycarboxylic acids include malic acid, tartaric acid and citric acid, and metal salts thereof.

The common feature of these organic acids is that they have the effect of delaying the setting effect on cement.However, even when the water-cement ratio is slightly increased, the reduction in strength is reduced within the appropriate usage range even when the water-cement ratio is slightly increased. is there.

In particular, oxypolycarboxylic acids also have an effect of preventing slump drop, which is a problem of concrete using the water reducing agent, from being fast.

The amount of organic acids used is 0.005 per 100 parts by weight of cement.
~ 0.5 parts by weight is preferred. A more preferred range is 0.01 to
0.35 parts by weight, the most preferred range is 0.05 to 0.25 parts by weight. At less than 0.005 parts by weight, the effect of increasing strength is small,
If the amount exceeds 0.5 part by weight, the retardation of setting and hardening is large, and the development of strength is too late, which is not preferable.

Examples of the cement to which the cement admixture of the present invention is added include various portland cements, mixed cements, and hydraulic materials based on slag powder.

As described above, the method of mixing and using each material of the present invention individually described is not particularly limited, and may be mixed in advance in a preferable compounding amount range for cement of each material, If the present water reducing agent is liquid, it may be used as a slurry composition together with the kneading water, and the effect is not changed at all even if the respective materials are separately blended during the production of concrete.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to examples.

REFERENCE EXAMPLE 1 Concrete is kneaded based on the mixing ratio of the water reducing agent and vermiculite based on the mixing ratio of the concrete shown in Table 1, and the viscosity, the standard curing and the material age after the air drying curing in a room at 20 ° C.
The compressive strength of the day (using a 10 mm × 20 cm specimen) was measured.

 Table 2 shows the results.

The concrete was kneaded in a room at 20 ° C. in a forced kneading mixer (capacity 100) for 60 minutes for 3 minutes, and the slump was the value immediately after kneading.

The viscosity measurement was performed by using a virus-knack-type plastometer shown in the drawing with only the sample container modified for concrete.

This apparatus and test method allow a sample vessel 3 to be added with an arbitrary weight 2 to a plunger 1 (weight 2.376 g) which is vertically dropped as shown in the drawing.
Is filled with concrete, and after smoothing, the collar 4 is added and set in the apparatus. Next, the plunger is fixed once with the screw 5 so that the tip of the plunger is in contact with the concrete surface at the center of the sample container. Then select an appropriate weight and put it on,
Unlock plunger, plunger 10cm and 5c
Two types of weights that penetrate and stop at around m are selected, and the weight of the weight at which the plunger penetrates and stops at 7.5 cm is calculated by proportional calculation. At this time, it is judged that the penetrability (penetration) is better and the viscosity has disappeared as the weight is smaller with the same slump.

<Materials used> Cement: ordinary Portland cement manufactured by Andes Cement Co., Ltd. Sand: Himekawa-produced river sand from Niigata Crushed stone: 砕 Crushed stone In addition, the same slump can be obtained by adding a water reducing agent to the concrete mix shown in Table 1. Although only a small amount of water is required, the slump was adjusted by simply reducing the amount of water used without modifying the amount of cement, sand, crushed stone, etc. In addition, in the cement admixture of the present invention added to cement, vermiculite was replaced with sand, and the water reducing agent was used as an outer weight%.
Addition.

 Table 2 shows the results.

All of the high-performance water reducing agents and inorganic substances used in Table 2 are commercially available and easily available.

<Materials> Water-reducing agent A-1: "Cellflow 110P" powder, polyalkylallyl sulfonate 〃 A-2: "Mighty 100" 〃, Vermiculite: Montana, USA (400 mesh under) Use) As shown in Experiment Nos. 1-1 to 1-7, as the amount of the water-reducing agent added increases, the water-reducing rate naturally increases and the strength also increases, but at the same time, the viscosity also increases and the plunger Penetration resistance increases.

As shown in Experiments Nos. 1-8 to 1-18, as the amount of vermiculite used increases, the viscosity decreases and the water-cement ratio also increases, so that the strength decreases sequentially.

Example 1 Example 1 was repeated except that gypsum and / or an active siliceous substance were used in combination with the water reducing agent and vermiculite as shown in Table-3. The results are shown in Table-3.

<Materials> Gypsum, B-1: Hard gypsum (by-product plaster of hydrofluoric acid) Active Si, C-1: Silica fume, manufactured by Nippon Heavy Industries, Ltd. 〃 C-2: Aerosil (5 m ² surface area) Nippon Aerosil ( 〃 C-3: Blast furnace slag fine powder, made by Nippon Steel, 10
μ C-4: fly ash 〃 Tokiwa fly ash, classified to 10μ or less As shown in Experiment Nos. 2-1 and 2-14, simply adding gypsum or an active siliceous substance to this water reducing agent had no effect of reducing viscosity at all, and the viscosity was reduced by using it together with vermiculite. In particular, when gypsum is used in combination, the indoor air-drying curing strength is large, and the strength decreases little due to the increase in the water-cement ratio by vermiculite.

Example 2 As shown in the composition of Table 4, the same procedure as in Example 2 was carried out except that inorganic salts and organic acids were used in combination. The results are shown in Table-4.

In addition, the change with time of the slump is repeated after measuring the slump of the kneaded concrete, leaving the concrete in a container and leaving it to stand, returning it to the mixer at an arbitrary time, kneading and measuring the slump. Done.

<Materials> Water reducing agent A-3: "Merment F-10", powder, melamine formalin resin sulfonate 〃 A-4: "Mighty 2000", liquid (solid content 45
%), Polyalkylallyl sulfonate 〃 A-5: “Mighty 150”, 〃 (solid content 42%),
〃 Ａ A-6: “FT-500”, 〃 (solid content 45%)
〃 〃 A-7: “Sunflow PSR120”, 〃 (solid content 44
%), 〃 〃 A-8: “Pole Fine 510N”, 〃 (〃
Gypsum B-2: 2 water gypsum (industrial) Gypsum B-3: hemihydrate gypsum (dry gypsum at 150 ° C. for 2 hours) Gypsum B-4: soluble anhydrous gypsum (addition of hemihydrate at 200 ° C.) Two
hr dried) Inorganic salts D-1: sodium bicarbonate, manufactured by Wako Chemical Co., Ltd., Reagent 1st grade 〃 D-2: sodium alum 〃, 〃 〃 D-3: sodium carbonate 〃, 〃 Ｄ D-4: potassium carbonate 〃, 〃 〃 D-5: Lithium carbonate 〃, 〃 Ｄ D-6: Sodium aluminate 〃, 〃 Ｄ D-7: Potassium aluminate 〃, 〃 Ｄ D-8: Sodium silicate 〃, 〃 Ｄ D-9: Sulfuric acid Aluminum 〃, 〃 Ｄ D-10: Magnesium sulfate 〃, 〃 Organic acids E-1: citric acid 〃 E-2: Sodium citrate, manufactured by Wako Chemical, first grade reagent 〃 E-3: Potassium citrate 〃, 〃 Ｅ E −4: Tartaric acid 〃, 〃 〃 E-5: Sodium tartrate 〃, 〃 Ｅ E-6: Potassium tartrate 〃, 〃 〃 E-7: Sodium malate 〃, 〃 〃 E-8: Sodium maleate 〃, 〃 〃 E-9: Potassium fumarate 〃, 〃 〃 E-10: Sodium malonate 〃 〃 〃 E-11: Sodium succinate 〃, 〃 Ｅ E-12: Glutaric acid 〃, 〃 〃 E-13: Adipic acid 〃, 〃 14 E-14: Potassium oxalate 〃, 〃 〃 E-15: Lactic acid Sodium 〃, 〃 〃 E-16: Sodium heptanoate 〃, 〃 〃 E-17: Calcium gluconate 〃, 〃 〃 E-18: Sodium glycolate 〃, 〃 Experiments show that alkali metal carbonates, bicarbonates and other inorganic salts help reduce the viscosity of vermiculite
o.3-1 to 3-19 are remarkably shown, and at the same time, an effect of increasing the strength is also found.

Experiments Nos. 3-20 to 3-25 show that if the organic salt is in an appropriate amount, the increase in the water-cement ratio by vermiculite, that is, the decrease in strength is suppressed.

Experiment Nos. 3-26 to 33 show the amount of organic acid added and the effect of increasing strength.

Further, among organic acids, polyvalent oxycarboxylic acids such as citric acid have a remarkable effect of preventing or reducing slump drop.

In Experiment Nos. 3-50 to 3-60, in each combination of high performance water reducing agent, vermiculite, gypsum, silica fume and blast furnace slag, inorganic salts and organic acids,
The properties of each individual component are exhibited without loss.

Example 3. After molding a test piece of 10φ × 20cm with concrete of Experiment Nos. 1-4 and Nos. 2-7 to 2-13, pre-curing was performed at 20 ° C. for 4 hours, and the temperature was raised to 20 ° C./hr. The temperature was raised to 75 ° C. in 3 hours at the following rate, and the temperature was maintained for 4 hours. After stopping the steam, the solution was allowed to cool naturally in a curing tank until the next day, and the strength was measured on the next day.

 The results are shown in Table-5.

From Table-5, it is suggested that the strength peak in the case of steam curing by blending the present water reducing agent, vermiculite and gypsum shifts to 10 to 13% by weight of gypsum and gradually decreases at 15% by weight or more. .

〔The invention's effect〕

As described above, by using the cement admixture of the present invention, the viscosity caused by the high-performance water reducing agent can be reduced, workability is improved, kneading of concrete, discharge molding from a hopper, finishing, etc. Handling has also improved,
Easy-to-handle concrete is obtained.

In addition, they exhibit high strength and prevent slump loss without impairing the properties of the constituent components.

[Brief description of the drawings]

The drawing is a schematic view of an apparatus for measuring penetrability according to the present invention. Symbol 1 ... plunger, 2 ... weight, 3 ... sample container, 4 ... color, 5 ... screw, 6 ... scale.

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ identification code FI // C04B 103: 32 (58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 24/24-24/30 C04B 22 / 08 C04B 14/20 C04B 22/14 C04B 22/06

Claims (2)

(57) [Claims] 1. A cement admixture comprising a high-performance water reducing agent, a main component of vermiculite of 400 mesh or less, gypsum and / or an active siliceous substance. 2. A cement admixture according to claim 1, which contains an inorganic salt and / or an organic acid of an alkali metal.