JP2003321264A - Hydraulic composition and its hardened body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a hydraulic composition which can develop a water reducing effect safely without any problem in the case that a polycarboxylic acid-based water reducing agent is used regardless of the temperature at production or construction work when obtaining a cement-based hardened body excellent in strength developability and durability by reducing a water/cement ratio using the reducing agent, and also to provide the hardened body. <P>SOLUTION: The hydraulic composition comprises (A) the polycarboxylic acid-based water reducing agent, (B) a cement, and (C) an alkaline (earth) metal slat of a carboxylic acid monomer having a molecular weight of 100 or less. The hardened body is obtained by compounding 100 pts.wt. of the hydraulic composition, 40-500 pts.wt. of an aggregate and water. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cement-based hydraulic composition suitable for water reduction and a cured product thereof.

[0002]

[Prior art and its problems] Cement mortar and concrete are treated with water / water to improve the strength and durability after hardening.
The cement ratio is being reduced. In this case, a water reducing agent is often used in order to prevent the separation phenomenon of the compounding material and the decrease in the fluidity of the cement-containing kneaded mixture due to the decrease in the water / cement ratio. Among the water reducing agents, the polycarboxylic acid-based high-performance water reducing agent whose main component is a comb-shaped polymer compound having a polyalkylene oxide or the like as a graft chain can significantly reduce the water / cement ratio even with a low addition amount,
It is known that high fluidity can be maintained. On the other hand,
Polycarboxylic acid type water reducing agents have strong temperature dependence, and it is difficult to maintain fluidity for a long time in high temperature environments such as in the midsummer, and excessive water reduction in low temperature environments such as outdoors during severe winters. It was easy to cause material separation and bleeding.

As a method for stably exhibiting the excellent properties of a polycarboxylic acid type water reducing agent even at high temperature, Japanese Patent Application No. 10-
It is disclosed in 318827 that by using a polymer flocculant in combination, the residual ratio of the water-reducing agent effective component in the cement hydrous kneaded product can be kept high and the deterioration of fluidity can be suppressed for a long time. However, the use of polymeric flocculants causes an increase in viscosity, which may hinder construction workability depending on the construction application, and eliminates the possibility of material separation and bleeding in low temperature environments. Not done.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a water-reducing agent to reduce the water / cement ratio to obtain a cement-based hardened product excellent in strength development and durability. An object of the present invention is to provide a hydraulic composition and a cured product thereof that can stably exhibit the water reducing effect when a carboxylic acid water reducing agent is used, regardless of the temperature during manufacturing and construction. .

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventor used an alkali metal salt and / or an alkaline earth metal salt of a specific monomer in combination with a polycarboxylic acid type water reducing agent. By doing so, it is possible to prevent the water-reducing agent active ingredient, which has a considerable difference in the amount and rate of dissolution depending on the temperature, from dissolving and reacting during or after construction,
The present invention has been completed based on the finding that the water-reducing action of cement is not caused excessively and the properties of the cement-containing kneaded mixture are stable for a long time. That is, the present invention includes the following (1) to
The hydraulic composition of (4) and the cured product of (5).

(1) (A) a polycarboxylic acid-based water reducing agent,
A hydraulic composition comprising (B) cement and (C) an alkali metal salt of a carboxylic acid monomer having a molecular weight of 100 or less and / or an alkaline earth metal salt of a carboxylic acid monomer having a molecular weight of 100 or less. (2) The hydraulic composition according to (1), wherein the carboxylic acid monomer having a molecular weight of 100 or less is formic acid. (3) The hydraulic composition according to (1) or (2), which contains (D) a ligninsulfonic acid-based water reducing agent. (4) (E) Blaine specific surface area 6000 cm ² /
The hydraulic composition according to any one of (1) to (3), which contains g or more of slag and / or (F) silica fume. (5)
A cured product obtained by mixing 100 parts by weight of the hydraulic composition according to any one of (1) to (4), 40 to 500 parts by weight of an aggregate, and water.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The hydraulic composition of the present invention comprises a polycarboxylic acid type water reducing agent, cement, an alkali metal salt of a carboxylic acid monomer having a molecular weight of 100 or less, and / or a molecular weight of 10.
It essentially contains an alkaline earth metal salt of a carboxylic acid monomer of 0 or less. The polycarboxylic acid-based water reducing agent used in the present invention has a polyalkylene oxide or the like as a graft chain and a comb-shaped polymer compound having a plurality of carboxyl groups as a main component, and may exhibit a water reducing effect. There is no particular limitation as long as it is a high-performance water reducing agent or a high-performance AE water reducing agent. The state may be either powder or liquid. The content of the polycarboxylic acid-based water reducing agent in the hydraulic composition of the present invention may be an amount generally used in mortar and concrete, for example, 0. It may be about 05 to 0.5 parts by weight.

The cement contained in the hydraulic composition of the present invention is not particularly limited, and examples thereof include various Portland cements, mixed cements and alumina cements.

The alkali metal salt of a carboxylic acid monomer having a molecular weight of 100 or less and / or the alkaline earth metal salt of a carboxylic acid monomer having a molecular weight of 100 or less contained in the hydraulic composition of the present invention is It means any of (b) or a mixture of both (a) and (b). (A) Any one or more of salts formed from an unpolymerized monomer having a carboxyl group and a molecular weight of 100 or less and an alkali metal such as lithium, sodium or potassium. (B) Any one or more of salts formed from an unpolymerized monomer having a carboxyl group and having a molecular weight of 100 or less and an alkaline earth metal such as calcium, magnesium or barium. Here, if the molecular weight of the carboxylic acid monomer exceeds 100, a setting retarding action is likely to be exhibited, and if used in a low temperature environment, material separation or bleeding may occur, which is not preferable. Alkali metal salt of carboxylic acid monomer having a molecular weight of 100 or less and / or molecular weight of 10
The content of the alkaline earth metal salt of a carboxylic acid monomer of 0 or less in the present hydraulic composition is preferably 0.05 to 1.0 part by weight with respect to 100 parts by weight of cement. If it is less than 0.05 parts by weight, the compounding effect will be poor, and if it exceeds 1.0 parts by weight, the fluidity retaining action will not be improved.

The carboxylic acid monomer having a molecular weight of 100 or less has a carboxyl group-containing molecular weight of 100.
Any of the following unpolymerized monomers may be used,
Formic acid is most preferable because the solubility of the polycarboxylic acid water reducing agent with time can be suppressed quite effectively.

The hydraulic composition of the present invention preferably contains a ligninsulfonic acid-based water reducing agent. By containing a lignin sulfonic acid-based water reducing agent, it is possible to express the fluidity retaining effect remarkably in the cement hydrous kneaded product even in a high temperature environment, so it is particularly effective to stably obtain high fluidity for a long time at the temperature. is there. As the lignin sulfonic acid-based water reducing agent, any water reducing agent containing a lignin sulfonic acid salt and / or its derivative as a main component, a high-performance water reducing agent, or a high-performance AE water reducing agent may be used. The content of the lignin sulfonic acid-based water reducing agent in the present hydraulic composition is less than 0.01 parts by weight with respect to 100 parts by weight of cement, and the compounding effect is poor, and when it exceeds 0.3 parts by weight, the fluidity retaining action is improved. Therefore, 0.01 to 0.3 parts by weight is recommended.

The hydraulic composition of the present invention preferably contains either or both of slag and silica fume having a Blaine specific surface area of 6000 cm ² / g or more. When the slag and / or silica fume having a Blaine specific surface area of 6000 cm ² / g or more is contained, a remarkable material separation suppressing effect can be exhibited even in any temperature environment where there is a possibility of construction requirements, and a hydraulic composition. The hydration reaction activity of the product can also be enhanced. The higher the fineness of powder is, the higher the effect of suppressing material separation is. Therefore, the slag has a Blaine specific surface area of 6000 cm ² / g or more.
Also, slag is blast furnace slag, steelmaking slag, converter slag,
Waste molten slag such as municipal waste and sewage sludge can be used. The silica fume is not particularly limited, and any known one can be used. Blaine specific surface area 6000 cm
The content of slag and / or silica fume of ² / g or more in the hydraulic composition is 100 parts by weight of cement,
If it is less than 0.5 part by weight, the compounding effect is poor, and if it exceeds 200 parts by weight, strength lowering or curing delay may occur and the fluidity retaining action may not be improved, so 0.5 to 200 parts by weight is recommended. It

The hydraulic composition of the present invention may contain components other than those mentioned above as long as the water-reducing effect is hardly impaired. Specific examples include thickeners, water retention agents, shrinkage reducing agents, expanders, AE agents, and any one or more of various admixtures / admixtures known to be commonly used with cement. But good.

The hardened material of the present invention comprises 100 parts by weight of the hydraulic composition, 40 to 500 parts by weight of aggregate and water. Further, it may be a hardened body to which other components known to be used for mortar and concrete, for example, known fibers and extenders are added. Aggregate is not particularly limited in type and particle size as long as it is an aggregate that can be used for mortar and concrete, and for example, river sand,
Examples thereof include crushed stone, silica stone, silica sand, silica stone powder, limestone, slag aggregate, clinker aggregate, and various artificial aggregates. If the amount of aggregate is less than 40 parts by weight, the static elastic modulus becomes high,
It is not preferable because resistance to strain is lowered, and when it exceeds 500 parts by weight, strength development is remarkably lowered, which is not preferable. Further, the amount of water to be blended can be a relatively low amount, and may be appropriately selected depending on the purpose of use and the content of the blend. For example, when the blending amount of water is approximately 35 to 80 parts by weight with respect to 100 parts by weight of the hydraulic composition, a cured product having good strength development can be obtained. When mixing,
There are no particular restrictions on the method of inputting the raw materials, mixing / kneading, etc., the equipment used, etc. Further, the construction method after curing, the curing method, the intended use, etc. are not particularly limited.

[0015]

EXAMPLES The present invention will be described below with reference to examples. [Materials used] The materials abbreviated as A to G below are used. A: Polycarboxylic acid type high performance water reducing agent (Pacific cement
NF-100 manufactured by Co., Ltd. B: Ordinary Portland cement (Pacific Cement Co., Ltd.)
C1: Sodium formate (Kanto Chemical Co., Ltd. first-grade reagent) C2: Sodium acetate (Kanto Chemical Co., Ltd. first-grade reagent) C3: Calcium formate (SAW East Asia Cellbest Accelerator) C4: Sodium citrate (First-class reagent manufactured by Kanto Chemical Co., Inc.) D: Lignin sulfonic acid-based water reducing agent (Pozoris No. 8 manufactured by Pozoris Bussan Co., Ltd.) E: Blast furnace slag (Summitment P manufactured by Sumitomo Kashima Mining Co., Ltd.)
BH-08; Blaine specific surface area of about 8000 cm ² / g) F: Silica fume (manufactured by Simcore) G: Aggregate (Yamagata Prefecture limestone powder; Blaine specific surface area of about 10)
00 cm ² / g)

[Preparation of mortar in low temperature environment and evaluation of its properties] The above materials A to G and water were added all at once so as to have the composition shown in Table 1, and mixed using a hand mixer at a temperature of 5 ° C. -Kneading was performed for about 2 minutes to prepare grout mortar. For this mortar, it was examined whether material separation and bleeding occurred. Immediately after the mortar was manufactured, the material separation was evaluated by using a mold tube with a diameter of 5 cm and a depth of 10 cm.
And the mixture was allowed to stand at a temperature of 5 ° C., and a portion (α) having a thickness of 1 cm from the top surface of the cured cured body after curing and a portion (β) having a thickness of 1 cm from the bottom surface were sampled. The calcium carbonate content of the collected material was quantified from the diffraction intensity by powder X-ray diffraction, and the difference in the calcium carbonate content contained in (α) and (β) was 10% by weight or more. When the content was less than 10% by weight, it was judged that the material separation was “none” because there was usually no problem in construction. In addition, the presence or absence of bleeding was evaluated at a temperature of 5 ° C. by a method according to JSCE-F532 of the Japan Society of Civil Engineers. Immediately after the preparation, the mortar was poured into a cylindrical mold having an inner diameter of 50 mm and a height of 100 mm, cured at 5 ° C. and 90% relative humidity for 24 hours, then demolded, and then cured at 5 ° C. for 4 weeks in water. A cured product was obtained. The compressive strength of the cured product was measured according to JIS A 1108.
It was measured by the method according to. The above results are also shown in Table 1. From the results in Table 1, virtually no material separation or bleeding was observed at low temperatures in any of the products of the present invention. on the other hand,
Significant material separation was observed in the reference product containing no alkali metal or alkaline earth metal salt of a carboxylic acid monomer having a molecular weight of 100 or less.

[0017]

[Table 1]

[Preparation of mortar in high temperature environment and evaluation of its properties] The materials A to G and water were added all at once so as to have the composition shown in Table 2, and mixed using a hand mixer at a temperature of 35 ° C. -Kneading was performed for about 2 minutes to prepare grout mortar. The fluidity of the mortar immediately after its preparation and the mortar after 30-90 minutes at the temperature of 35 ° C. from the preparation were evaluated by measuring the J14 funnel flow-down time by the method according to JSCE-F541. The measurement results are shown in Table 2. It can be seen from Table 2 that all the products of the present invention stably show high fluidity even at a high temperature of 35 ° C. for a long time with a small fluctuation range over time.

[0019]

[Table 2]

[0020]

EFFECTS OF THE INVENTION The hydraulic composition according to the present invention is excellent in workability because it can maintain high fluidity stably for a long time regardless of temperature even if the mixing ratio of water is low. Since bleeding is unlikely to occur, it is possible to easily obtain a cured product of stable quality, particularly a cured product of high strength and high durability, regardless of the temperature during construction / manufacturing.

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Claims (5)

[Claims] 1. A polycarboxylic acid-based water reducing agent, (B)
A hydraulic composition comprising cement and (C) an alkali metal salt of a carboxylic acid monomer having a molecular weight of 100 or less and / or an alkaline earth metal salt of a carboxylic acid monomer having a molecular weight of 100 or less. 2. The hydraulic composition according to claim 1, wherein the carboxylic acid monomer having a molecular weight of 100 or less is formic acid. 3. The hydraulic composition according to claim 1, which comprises (D) a ligninsulfonic acid-based water reducing agent. 4. (E) Blaine specific surface area of 6000 cm ^2.
The hydraulic composition according to any one of claims 1 to 3, which contains slag and / or (F) silica fume in an amount of / g or more. 5. A cured product obtained by mixing 100 parts by weight of the hydraulic composition according to any one of claims 1 to 4, 40 to 500 parts by weight of aggregate and water.