JPH1171147A - Cement admixture and cement composition by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cement admixture capable of extremely improving a water-reducing rate and providing a high strength by including a high performance water-reducing agent, a bicarbonate of sodium or potassium, tripolyphosphate and ammonium bicarbonate. SOLUTION: This cement admixture comprises a high performance water- reducing agent consisting essentially of a polyalkylallylsulfonate-based, a melamine formaldehyde resin sulfonate-based, and an aromatic aminosulfonate-based high performance water-reducing agents, a bicarbonate of sodium or potassium, tripolyphosphate and ammonium bicarbonate. The compounding proportion of the high performance water-reducing agent and the bicarbonate or the like is 0.3-3 pts.wt. of the high performance water-reducing agent and 0.05-0.7 pts.wt. of the bicarbonate or the like expressed in terms of the solid based on 100 pts.wt. cement. Gypsums (e.g. gypsum trihydrate) and/or activated silica (e.g. a silica fume) can be added to the cement admixture. An acid clay or the like can be added thereto as a pozzolanic material. The addition amounts are 1-15 pts.wt. of the gypsums, 1-10 pts.wt. of the activated silica and 1-15 pts.wt. of the pozzolanic material based on 100 pts.wt. of the cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture for mortar and concrete used in civil engineering and building structures and secondary concrete products, and a cement composition using the same. More specifically, the present invention relates to a cement admixture for greatly increasing a water reduction rate and easily obtaining high strength, and a cement composition using the same.

[0002]

BACKGROUND OF THE INVENTION High performance water reducing agents such as polyalkylallyl sulfonate, melamine formalin resin sulfonate, and aromatic amino sulfonate polymers are
Compared with general water reducers such as lignin sulfonate, polyol-based water reducer and oxycarboxylate-based water reducer, the water reduction rate is large, and abnormal setting and excessive delay of cement even when added in relatively large amounts. It is suitable for increasing the strength of mortar or concrete used in civil engineering and building structures and concrete products, since it does not cause any air entrainment. Further, in order to increase the strength, it is a usual means to use a high-performance water reducing agent, a high-strength admixture mainly composed of gypsum, active silica or the like, or a pozzolanic substance together with the high-strength admixture.

[0003] However, these high-performance water reducing agents are limited to about 2 parts by weight in terms of solid content with respect to 100 parts by weight of cement, and the water reduction rate reaches a limit, indicating a limit. In addition, the strength when the high-strength admixture is added is ultimately determined by the water-cement ratio.Therefore, if the water reduction rate can be increased, not only can higher strength be easily obtained, but also the strength can be kept constant. In this case, the unit cement amount and the unit high-strength admixture amount can be reduced, and economical concrete production becomes possible.

[0004] When a high-performance water reducing agent is used in combination with an alkali metal bicarbonate or the like, the inventor of the present invention added citric acid, tartaric acid, malic acid or salts thereof and an alkali metal carbonate to concrete containing the high-performance water reducing agent. Proposed a method of improving the workability of concrete for preventing slump loss by adding bicarbonate (Japanese Patent Publication No. 1-52342).

However, in a combined system of citric acid or the like and an alkali metal bicarbonate, the alkali metal bicarbonate or the like has an excellent effect in promoting slump loss prevention, but has no effect of increasing the water reduction rate. Things.

Further, the present inventors have proposed a cement admixture in which a high-performance water reducing agent, bentonite, etc., and a bicarbonate of an alkali metal are used in combination, and improve the abnormal viscosity of concrete to which the high-performance water reducing agent is added. Also, an admixture that has good water retention and good plasticity and does not cause sagging, and also improves ironing finish has been proposed (JP-A-64-3040). However, also in this case, the alkali metal bicarbonate and the like show a great effect in improving the plasticity of bentonite, but also in this case, the effect of increasing the water reduction rate is not recognized. Shows completely different properties when used in combination with other components.

The present inventors have conducted intensive studies for the purpose of increasing the water reduction rate of a high-performance water reducing agent and easily obtaining high strength, and as a result, it has been conventionally known as a cement retarder and a setting accelerator. The present inventors have found that the present invention can be achieved by using a specific component in a specific amount and further using gypsum, active silica, and a pozzolan substance in combination, and have completed the present invention.

[0008]

That is, the present invention relates to (1) a high-performance water reducing agent and one of sodium or potassium bicarbonate, tripolyphosphate and ammonium bicarbonate.
The cement admixture according to claim 1, wherein the cement admixture comprises: a seed or two or more kinds; (2) gypsum and / or active silica;
(3) It contains a pozzolanic substance (1)
Or (2) a cement admixture, (4) a cement composition containing the cement and the cement admixture according to any of (1) to (3), and (5) 100 parts by weight of cement. 0.3 to 3 parts by weight of a high-performance water reducing agent in terms of solid content, and 0.05 to 0.7 of one or more of sodium or potassium bicarbonate, tripolyphosphate, and ammonium bicarbonate. 1 to 15 parts by weight of gypsum in terms of CaSO ₄ and / or 1 to 10 parts by weight of activated silica, and 1 to 15 parts by weight of a pozzolanic substance. It is.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The high-performance water reducing agent used in the present invention is a polyalkylallyl sulfonate-based, melamine formalin resin sulfonate-based, aromatic aminosulfonate-based high-performance water reducing agent as a main component, among which One or more of them may be used in combination.

As an example of a commercially available high-performance water reducing agent, examples of a polyalkylallyl sulfonate-based high-performance water reducing agent include methyl naphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, and Salts such as anthracenesulfonic acid formalin condensate are listed as commercial products, and "FT-500" manufactured by Denki Kagaku Kogyo Co., Ltd. and "Mighty 1" manufactured by Kao Corporation
00 ”,“ Mighty 150 ”,“ Mighty 2000 ”
Series, etc., brand name “CELLFLOW 11
0P ”and other product names manufactured by Takemoto Yushi Co., Ltd.
N ”and other product names from Sanyo Kokusaku Pulp“ Sunflow P
S "," Sunflow HS700 "and the like. Further, as an aromatic aminosulfonate, there is a "Parick 200" series manufactured by Fujisawa Pharmaceutical Co., Ltd. Further, as a melamine formalin resin sulfonate-based high-performance water reducing agent, trade name "FT-3S" manufactured by Denka Grace Co., Ltd.,
"Molmaster 10" and "Molmaster 20" (trade names, manufactured by Showa Denko KK) (hereinafter simply referred to as high-performance water reducing agents). Among these, “Mighty 100”, “Cell Flow 110P”, which are commercially available in powder form,
"Mole Master 10", "Mole Master 20"
Others are commercially available in liquid form, and the polyalkylallyl sulfonate-based high-performance water reducing agent has a solid content of about 40% by weight.

In general, sodium or potassium bicarbonate of the present invention is used in a general water reducing agent such as a lignin sulfonate, a polyol-based water reducing agent, an oxycarboxylate-based water reducing agent, or a high-performance AE water reducing agent such as a polycarboxylate-based water reducing agent. Even when a salt, tripolyphosphate and ammonium bicarbonate are used in combination, the water-reducing effect is too small to be industrially available or, conversely, the water-reducing rate may be reduced, so that they cannot be used in the present invention.

The sodium or potassium bicarbonate, ammonium bicarbonate and the like of the present invention are known as a setting and hardening accelerator of cement or as a quick setting agent depending on the amount of addition, and are mainly used as a quick setting agent for sprayed concrete. Has been used as. In addition, sodium and potassium tripolyphosphates are known as cement setting retarders (hereinafter simply referred to as bicarbonates and the like).

These bicarbonates and the like have a remarkable action of improving the water reduction rate when used in combination with a high-performance water reducing agent in a range that does not cause rapid setting or hardening. Lithium carbonates, bicarbonates, and ammonium carbonate, which are metals, have little effect of improving the water reduction rate.

The mixing ratio of the high-performance water reducing agent and bicarbonate is as follows:
With respect to 100 parts by weight of cement, 0.3 to 3 parts by weight of the high-performance water reducing agent in terms of solid content, and 0.05 to 0.
It is preferable to mix in a range of 7 parts by weight. If the amount of bicarbonate is appropriate, the higher the amount of the high-performance water reducing agent, the higher the water reduction rate. When the amount of the water reducing agent is less than 0.3 parts by weight, the effect of addition is small even when the proper amount of bicarbonate is blended. Even when the amount of the high performance water reducing agent exceeds 3 parts by weight, the amount of bicarbonate is not appropriate. Even so, the improvement of the water reduction rate will reach a plateau.

When the amount of bicarbonate or the like is less than 0.05 part by weight with respect to 100 parts by weight of cement, the effect of improving the water reduction rate is small even if the water reducing agent is used in an appropriate amount. Is not preferable because the water reduction rate is reduced irrespective of the amount of the high-performance water reducing agent added, or rapid setting occurs or over-delay occurs. Most preferably, with respect to 100 parts by weight of cement, the high-performance water reducing agent or the like is 0.4 to 0.4 in terms of solid content.
2.0 parts by weight, bicarbonate and the like are 0.1 to 0.5 parts by weight.

In the present invention, a high-strength admixture containing various gypsums or type II anhydrous gypsum as a main component (hereinafter referred to as gypsum).
Is blended. Gypsum and the like have a promoting effect on the improvement of the water reduction rate of the present invention, and higher strength can be easily obtained with concrete of the same composition, and the amount of gypsum and the like can be reduced when the strength is constant. Things.

The gypsum or the like of the present invention is a high-strength admixture mainly composed of gypsum dihydrate, hemihydrate gypsum, type III anhydrous gypsum, type II anhydrous gypsum, and type II anhydrous gypsum. Include Denka Co., Ltd. brand name "Denka @ 1000", Sumitomo Osaka Cement Corporation brand name "Nonclave", Nippon Cement Corporation brand name "Supermix", Showa Mining Co., Ltd. brand name "Alsam and Dymix" Can be

The mixing ratio of gypsum or the like, with CaSO ₄ terms, with respect to 100 parts by weight of cement, 1 to 15 parts by weight CaSO ₄ terms, more preferably 2 at normal temperature curing
To 8 parts by weight, and 3 to 12 parts by weight for steam curing. If the amount is less than 1 part by weight, the effect of increasing the strength and the effect of reducing the water reduction rate are small irrespective of the curing method, and the addition of more than 15 parts by weight is not preferable because the effect of increasing the strength and promoting the water reduction rate stagnates. .

The active silica used in the present invention is silica fume, calcined ash of silicified wood, metakaolin, aerosil and the like. Silica fume is amorphous SiO generated when metal silicon or a silicon alloy is produced in an electric furnace.
₂ is ultra-fine powder, and burned ash of silicified wood is rice husk, rice straw,
Reeds, firing ash silicified wood such as bamboo, metakaolin kaolinite, Dekkaito, amorphous aluminosilicate compound calcined kaolin minerals such as halloysite, AEROSIL is a micronized amorphous SiO ₂ comprised .

The mixing ratio of the active silica is 100
The amount is 1 to 10 parts by weight with respect to parts by weight, and the strength is increased, but is preferably 8 parts by weight or less, more preferably 2 to 6 parts by weight. If less than 1 part by weight, the effect of increasing strength is small, and even if added in excess of 10 parts by weight, combined use with bicarbonate or the like lowers the water reduction rate and causes false coagulation,
It is not preferable because the strength is also reduced.

The pozzolanic substance used in the present invention includes acidic clay, activated clay, pyroferrite, zeolite, kaolin minerals and other alumina siliceous clay minerals (excluding bentonite), and their calcined materials. (Excluding metakaolin), fly ash, blast-furnace slag powder (also a latent hydraulic substance), diatomaceous earth, etc., and when used in combination with bicarbonate, etc., become active and higher strength is obtained. become. However, there is no adverse effect such as false coagulation unlike activated silica.

The mixing ratio of the pozzolanic substance is
The amount is 1 to 15 parts by weight, preferably 2 to 12 parts by weight, more preferably 4 to 10 parts by weight with respect to 0 parts by weight. If the amount is less than 1 part by weight, the effect of addition is small, and if the amount exceeds 15 parts by weight, the effect of increasing the strength further stagnates, which is economically undesirable.

The gypsum, active silica and pozzolan substances are different from each other in terms of the strength effect obtained by a single compound.
When used arbitrarily, a synergistically high strength can be obtained.

Examples of the cement used in the present invention include various portland cements such as ordinary, fast, super fast, white, moderate heat, and low heat (belite cement), and blast furnace slag, fly, and the like. Examples include various mixed cements containing ash or silica powder, slag-based cements containing slag at or above the JIS standard value, and the like.

The cement admixture of the present invention is added to a mixer together with other concrete materials when kneading mortar or concrete, and the kneading method may be a conventional method. The addition method is not particularly limited.

Therefore, each component, whether solid or liquid, may be added separately when kneading the mortar or concrete. When a powdered high-performance water reducing agent is used, it may be added to the other components in powder form in advance. You may mix and add all at once. Alternatively, bicarbonate or the like may be dissolved in a liquid high-performance water reducing agent or the like and added separately from other solid components, or the entire admixture may be kneaded and mixed with part or all of the water. It may be turbid and added to the mixer. The most preferred method is to add an admixture in which all components are mixed (using a powder as a high-performance water reducing agent) when kneading mortar or concrete.

[0027]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Less than,
Various materials used in the examples are shown collectively.

<Materials Used> Cement: Ordinary Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Crushed stone: Crushed stone from Himekawa, Niigata Prefecture River sand: Natural sand from Himekawa, Niigata Prefecture Water: Groundwater “High-performance water reducing agent” A: Polyalkylallyl sulfonate B: Melamine formalin resin sulfonate, trade name “Molmaster 10” by Showa Denko, powdered “bicarbonate, etc.” a: heavy Sodium carbonate: Reagent 1st grade b. Ammonium bicarbonate: reagent primary c. Potassium bicarbonate: reagent primary d. Sodium tripolyphosphate: Reagent 1st grade “gypsum” a. Type II anhydrous gypsum: hydrofluoric acid generating by-product gypsum, Blaine specific surface area 6000 cm ² / g b. Gypsum dihydrate: Industrial (Brain specific surface area 6500
cm ² / g) c. Hemihydrate gypsum: b) heat treatment at 140 ° C (Brain specific surface area: 10,000 cm ² / g or more) d. Type III anhydrous gypsum (soluble): heat treated at 200 ° C. (Brain specific surface area 10,000 cm ² / g or more) “Activated silica” α. Silica fume: BET specific surface area 19.2 m ² / g β. Incinerated ash of silicified wood (rice straw): BET specific surface area 1.0
m ² / g γ. Metakaolin: A product obtained by firing [SEM clay] (trade name, manufactured by Kanto Bentonite Mining Co., Ltd.) at 700 ° C. and pulverized to a Blaine specific surface area of 8150 cm ² / g ε. Aerosil: Nippon Aerosil Co., Ltd., BET specific surface area 160 m ² / g “Pozzolanic substance” Kaolin: Product name manufactured by Kanto Bentonite Mining [SE
M clay] to a Blaine specific surface area of 8050 cm ² / g II. Heat-treated acid clay: Kanto Bentonite Mining Co., Ltd. Acid clay is calcined at 1000 ° C and Blaine specific surface area is 5500cm
Pulverized to ² / g III. Heat treated product of zeolite: Zeolite G35 product of Kanto Bentonite Mining Co., Ltd. calcined at 1000 ° C. and pulverized to a Blaine specific surface area of 6500 cm ² / g IV. Fly ash: Fly ash (Brain specific surface area: 3500 cm ² / g) from Tohoku Electric Power Co., Inc.
Crushed to 00 cm ² / g Diatomaceous earth: Kanto bentonite mining company [Celi
teFC] pulverized to a specific surface area of 7000 cm ² / g VI. Blast furnace slag powder: Nippon Steel Chemical Co., Ltd., Blaine specific surface area 4500 cm ² / g

Example 1 Using a mortar mixture of 100 parts by weight of cement, 135 parts by weight of sand and 28 parts by weight of water, kneading was performed by changing the mixing ratio and amount of the high-performance water reducing agent and bicarbonate in the powder. The mortar flow immediately after mixing was measured. The results are shown in Tables 1 to 3.
In addition, the mixing of the mortar, a part of the sand and mixing water and a high-performance water reducing agent into a kneading bowl, dissolve while stirring at low speed,
Then, lightly mix the cement and bicarbonate etc. with 3
Pour in within 0 seconds and then pour sand in 30 seconds. Further, after the kneading was continued for 60 seconds, the stirring was stopped once, the material attached to the pot was scraped off with a spatula, and then kneading was performed at a high speed for 90 seconds. In addition, the measurement of the mortar flow was such that the diameters of the bottom and top sides were 12 cm and 7 c, respectively.
The spread of the mortar when the flow cone was pulled out on a glass plate using a cone having a height of 10 cm and a height of 10 cm was measured immediately after kneading. The test room temperature is 20 ± 3 ° C.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

From Tables 1 to 3, the flow values when the amount of the high-performance water reducing agent was added were simply changed (for example, from Experiment No. 1-1 to Experiment No. 1).
No. 1-8, Comparative Example), when a high-performance water reducing agent and an appropriate amount of sodium bicarbonate were added together (Experiment No. 1-9 to Experiment No. 1-17, Example), the high-performance water reducing agent was used. The flow increases as the added amount of the cement increases, and the high performance water reducing agent
At 0.3 parts by weight or more with respect to 0 parts by weight, a remarkable effect is shown, and it is shown that 0.4 parts by weight or more is more preferable. In addition, when the amount of the high-performance water reducing agent exceeds 3 parts by weight, the effect of increasing the flow levels out. When the amount of the bicarbonate or the like is changed while the amount of the high-performance water reducing agent is kept constant (for example, Experiment No. 1-18 to Experiment No. 1-26, Example), the addition amount of the bicarbonate etc. increases. The more the flow rate, the more the flow rate is improved. However, the flow rate becomes remarkable at 0.05 parts by weight or more with respect to 100 parts by weight of cement, and most preferably at 0.1 parts by weight or more. Also,
At 0.7 parts by weight or more, the effect of increasing the flow tends to decrease, and at the same time, false coagulation (however, the flow does not recover even after re-kneading) may occur after about 20 minutes of mixing. The most preferred upper limit is 0.5 parts by weight. Further, although the effect of increasing the flow differs depending on the type of bicarbonate or the like, ammonium bicarbonate is most preferred, and tripolyphosphate is shown to be slightly inferior, but it is easy to use because it does not cause pseudocoagulation.

Example 2 Gypsum, activated silica, and pozzolanic substances were arbitrarily combined using the basic concrete composition shown in Table 4, and the kinds and amounts thereof were changed and added to 100 parts by weight of cement in an external manner.

[0035]

[Table 4]

The concrete was kneaded with 40 liters of concrete by adjusting the mixing water amount so that the slump was constant. At this time, the amount of mixing water used was recorded and converted into a water-cement ratio.
m specimens were prepared, and the compressive strength at 28 days of standard curing and the 1-day strength after steam curing were measured. The results are shown in Tables 5 to 7. The mixing of concrete is 20
Perform with a planetary forced kneading mixer in a room with a temperature of ± 3 ° C, add crushed stone from Himekawa, Niigata Prefecture, sand, and cement (when adding gypsum, etc., lightly mix the cement), then add a high-performance water reducing agent or high-performance A water reducing agent and potassium bicarbonate were kneaded, and a solution dissolved in the whole amount of water was added and kneaded for 2 minutes. After 4 hours of steam curing, the temperature was raised to 75 ° C. in 3 hours, kept for 4 hours, and then the steam valve was stopped and cooled in the curing tank until the next day.

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

As shown in Tables 5 to 7, the use of the high-performance water reducing agent of the present invention and an admixture such as bicarbonate can reduce the water-cement ratio by 3% to obtain concrete of the same slump. As a result, high strength can be easily obtained (comparison between Experiment No. 2-1 and Experiment No. 2-13). High strength can be obtained by using the high-performance water reducing agent of the present invention, bicarbonate or the like, and further gypsum. Among gypsums, type II anhydrous gypsum tends to lower the water-cement ratio, and exhibits an excellent effect in terms of strength (Experiment Nos. 2-5, 2-10 to 2-12 and 2 -17, 2-22
Comparative Examples 2-24) and 12 parts by weight of type II anhydrous gypsum in the comparative example, higher strength is obtained by adding 6 parts by weight in the examples. (Experiment No.2-8 and 2-17 comparison).

At room temperature, type II anhydrous gypsum suddenly increases in strength from 2 parts by weight, shows a peak at 6 parts by weight, and then gradually decreases, but when it exceeds 8 parts by weight, the strength decreases significantly. Is shown. In addition, in the case of steam curing, the strength is remarkably increased from 2 to 3 parts by weight, and the strength increases as the amount of addition increases, but reaches a plateau when it exceeds 12 parts by weight (Experiment No. 2-13). ~ 2-21).

When the high-performance water reducing agent of the present invention, bicarbonate or the like, and active silica are used in combination, the strength increases as the amount of addition increases, regardless of the curing method. When it exceeds 8 parts by weight, it reaches a plateau, and it is preferably 8 parts by weight or less, more preferably 2 to 6 parts by weight (Experiment Nos. 2-34 to 2-42).

In the combined use of the high-performance water reducing agent of the present invention, bicarbonate and the like, and a pozzolanic substance, the addition amount is 2 regardless of the curing method.
The strength is remarkably increased from the weight part, and the strength increases as the added amount increases. However, when the weight exceeds 12 weight parts, the strength reaches a peak, preferably 12 weight parts or less, more preferably 4 to 4 weight parts.
10 parts by weight (Experiment Nos. 2-56 to 2-6)
3).

When a high-performance water reducing agent, bicarbonate or the like, gypsum, active silica and pozzolanic substances are used in any combination, an extremely high strength can be obtained irrespective of the curing method (Experiment No. 1). 2-73 to 2-76).

[0045]

By using the cement admixture of the present invention and the cement composition using the same, the water reduction rate of the conventional high performance water reducing agent can be greatly improved, and high strength can be easily obtained. It becomes possible. Therefore, when the strength is constant, not only is it economical because the amount of the high-performance water reducing agent and the amount of unit cement and the amount of gypsum, active silica, and pozzolanic substances used can be reduced, and the heat of hydration can be reduced. The ideal concrete can be manufactured.

Claims (5)

[Claims] 1. A cement admixture comprising a high-performance water reducing agent and one or more of sodium or potassium bicarbonate, tripolyphosphate and ammonium bicarbonate. 2. The cement admixture according to claim 1, which contains gypsum and / or activated silica. 3. The cement admixture according to claim 1, wherein the cement admixture contains a pozzolanic substance. 4. A cement composition comprising a cement and the cement admixture according to claim 1. 5. A water-reducing agent having a solid content of 0.3 to 3 parts by weight, based on 100 parts by weight of cement, and one of sodium or potassium bicarbonate, tripolyphosphate and ammonium bicarbonate. Or two or more kinds of 0.05 to 0.7
1 to 15 parts by weight of gypsum in terms of CaSO ₄ and / or 1 to 10 parts by weight of activated silica, and 1 to 15 parts by weight of a pozzolanic substance. .