JPH04108646A - Cement admixture - Google Patents

Abstract

PURPOSE:To provide a cement admixture capable of preventing a decrease in the fluidity of concrete with the progress of time by mixing the high condensation product of two kinds of specified, aromatic sulfonic acids and formalin and the olefinic/ethylenic unsaturated dicarboxylic acid copolymer in a specified ratio. CONSTITUTION:(A) The high condensation product of naphthalenesulfonic acid and formalin, (B) the high condensation product of melaminesulfonic acid and formalin having 5,000-100,000 average mol.wt. and (C) the olefinic/ethylenic dicarboxylic acid copolymer (e.g. isobutylene/maleic anhydride copolymer) having; 500-50,000 average mol.wt. and 0.1-50mum average grain diameter and/or its hardly water-soluble salt (e.g. zincate) are prepared. The A component, B component and C component are mixed in the weight ratio of (90-30)/(70-10)/(0.5-10) to produce a cement admixture. The cement added with this admixture is appropriately used for the concrete for tunneling, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an admixture for cement or cement mixtures, and more particularly for increasing the fluidity of hydraulic cement mixtures such as concrete, mortar or paste. This invention also relates to a cement admixture that prevents fluidity from decreasing over time and improves its workability and workability.[Prior art] Conventionally, cement, water, and if necessary sand, After kneading, the cement mixture made by mixing gravel and admixtures (materials) is
Physical and chemical agglomeration of cement particles progresses over time, gradually losing fluidity and reducing workability/workability over time. For this reason, cement compositions have the disadvantage that their construction time (pot life) is limited.

Further, after being mixed, the cement mixture is often transported to the casting site by an agitator truck (ready concrete mixer truck), and the time required for transportation varies greatly depending on the transportation distance, traffic congestion, etc. For this reason, fluidity differs depending on the agitator car at the pouring site, making it extremely difficult to achieve consistent workability.

In addition, when pumping a cement mixture, if the pumping is temporarily interrupted due to a work stoppage or setup change, and then the pumping is restarted, the fluidity of the cement mixture in the piping will decrease, and when the pumping is resumed, the There are many problems such as a sudden increase in the pumping pressure or a blockage occurring in the piping.

In the case of centrifugally compacted concrete or mortar, after mixing, centrifugal forming forms are filled with concrete, and centrifugal compaction is often started when several forms have been filled. In this case, if it takes time to fill the formwork, the fluidity of the concrete will decrease, making centrifugal compaction difficult. For this reason, several methods have been proposed to prevent the decline in fluidity of cement mixtures.

For example, there is a method of adding a curing retarder such as oxycarboxylic acid for the purpose of preventing chemical aggregation. Although this method can delay the hydration reaction of cement, it is difficult to prevent physical agglomeration.

There is also a method of preventing slump loss by adding a granular dispersant to concrete and gradually dissolving it (Japanese Patent Application Laid-Open No. 139929/1983). Although this method can prevent slump loss to some extent, undissolved particulate dispersant remains after curing, resulting in disadvantages such as a decrease in strength.

There is also a method of preventing slump loss by adding a dispersant in portions (Japanese Patent Publication No. 15856/1983). Although this method is effective as a method for preventing slump loss, it is time-consuming and furthermore, it cannot prevent slump loss in concrete in situations where it is difficult to add in portions, such as during pumping piping.

Furthermore, there is a method in which a micronized product of a copolymer of lower olefin and maleic anhydride (for example, Japanese Patent Publication No. 63-5346) is added to a cement mixture to have a sustained release effect, thereby preventing the formation of cement particles. This method is effective as a method for preventing slump loss, but the finely divided copolymer of slow-released lower olefin and maleic anhydride delays the hydration reaction of cement, so it is difficult to obtain a normal hardening speed. There is a limit to the amount of addition, that is, there is a limit to the effect of preventing slump loss.

C Problems to be Solved by the Invention] As described above, the conventional methods have disadvantages such as delayed hardening of concrete and localization of the dispersant, which reduces the strength and durability of concrete.

For this reason, concrete, which is a hydraulic cement mixture,
It has been desired to develop an admixture that would prevent the workability of mortar or paste from deteriorating over time and would not delay the hardening of cement mixtures.

[Means to solve the problem]

The present invention was made to improve the drawbacks of the conventional methods described above, and the present inventors have developed a naphthalene sulfonic acid formalin high condensate, a melamine sulfonic acid formalin high condensate having an average molecular weight within a specific range, and a melamine sulfonic acid formalin high condensate having an average molecular weight within a specific range. According to a cement admixture obtained by using a copolymer of an olefin and an ethylenically unsaturated dicarboxylic acid having an average particle size within a specific range and/or a poorly water-soluble salt of the copolymer in a specific weight ratio. They discovered that it is possible to manufacture ideal concrete that effectively prevents the decline in workability over time without delaying the increase in strength of concrete after hardening, and has completed the present invention.

That is, the present invention provides (A) naphthalene sulfonic acid formalin high condensate, (B
) melamine sulfonic acid formalin high condensate with an average molecular weight of 5,000 to 100,000, and (C) an olefin and ethylenically unsaturated dicarboxylic acid with an average molecular weight of 500 to 50,000 and an average particle size of 0.1 to 50. The weight ratio of the copolymer with and/or poorly water-soluble salt of the copolymer is (A) / (B) / (C) = 90
The present invention provides a cement admixture characterized in that it is blended in a range of 30/70 to 1010.5 to 10.

The present inventors have already proposed an olefin and maleic anhydride copolymer (Japanese Patent Publication No. 63-5346) and its metal complex (Japanese Patent Application Laid-Open No. 62-83344) as a cement dispersant with the effect of preventing slump loss. Furthermore, as a result of intensive studies to make these components work more efficiently, the combined use of melamine sulfonate formalin high condensate and naphthalene sulfonate formalin high condensate resulted in greater slump loss than when each component was used alone. We found that the prevention effect was dramatically improved.

Here, the combined use of naphthalene sulfonic acid formalin high condensate and melamine sulfonic acid formalin high condensate not only effectively adsorbs to the cement surface and contributes to dispersion, but also
The high molecular weight melamine sulfonic acid formalin high condensate creates a steric effect to form a thicker adsorption layer compared to when each is used alone, minimizing the consumption of dispersant over time and reducing the It is presumed that the olefin and maleic anhydride copolymer or its sparingly water-soluble metal salt can effectively prevent the fluidity from decreasing over time.

The contents of the present invention will be explained below.

The present invention relates to (A) a naphthalene sulfonic acid formalin high condensate, (B) a melamine sulfonic acid formalin high condensate, and (C) a copolymer of an olefin and an ethylenically unsaturated dicarboxylic acid, and/or water resistance of the copolymer. Soluble salt weight ratio (A)/(B)/(C) = 90-30/7
This cement admixture is characterized in that it is used in combination in the range of 0 to 1010.5 to 10. If the amount of the component (^) increases beyond this range, it is necessary to increase the component (C) in order to prevent the fluidity from decreasing over time, resulting in delayed curing.

On the other hand, if component (B) is increased too much, the dispersibility will be significantly reduced. In addition, when the ratio of component (C) is 10 or more,
The curing retardation effect of cement increases and prevents proper strength development of concrete. In order to effectively prevent the deterioration of fluidity over time without causing curing delay, it is necessary to use components (A) to (C) together in the weight ratio within the above range.

The naphthalene sulfonic acid formalin high condensate (A) used in the present invention is a formalin condensate salt having naphthalene sulfonic acid as the main skeleton, and contains impurities such as methylnaphthalene sulfonic acid formalin condensate salt and creosote oil. This is a formalin condensate salt of a sulfonic acid starting from a raw material whose main component is a naphthalene skeleton.

The melamine sulfonic acid formalin high condensate (B) used in the present invention preferably has an average molecular weight of 5,000 to 100,000, more preferably 8,000 to 50,000. If the average molecular weight is smaller than this range, only the dispersion ability will take priority and sufficient slump retention effect will not be obtained.If the average molecular weight is larger than this range, the effect as a flocculant will be greater than as a dispersant, resulting in slump loss. Does not show any preventive effect.

The average particle size of the copolymer of olefin and ethylenically unsaturated dicarboxylic acid or salt thereof (C) used in the present invention is 0.
1 to 50 β, more preferably 0.1 to 5. If the average particle diameter is less than 0.1 β, the sustained release rate is too fast and the slump retention performance of concrete cannot be obtained. On the other hand, 5
If the length exceeds 0.01 m, the sustained release rate will be slow, and the amount added will increase and become localized, adversely affecting the physical properties of the concrete. Therefore, if the particle size is not optimal, it is necessary to use a pulverizer to crush it. The pulverizer used here is a commonly used pulverizer, such as a ball mill atrizer, a sand mill, and the like.

In the present invention, the average molecular weight of the copolymer (salt) of component (C) is preferably 500 to 50,000; if the average molecular weight is smaller than this range, the dispersing ability is insufficient, and if the average molecular weight is larger than this range, the dispersing agent It has a greater effect as a coagulant than as a coagulant, and does not exhibit the effect of preventing slump loss.

The average molecular weight shown here is the weight average molecular weight determined by aqueous gel permeation chromatography using polystyrene sulfonic acid as a reference material.

Component (C) of the present invention is a poorly water-soluble copolymer of an olefin and an ethylenically unsaturated dicarboxylic acid, and the olefin forming the copolymer is preferably an olefin having 2 to 8 carbon atoms, such as ethylene, propylene, etc. , n-butene,
Inbutylene, n-pentene, cyclopentene, 2-methyl-1-butene, n-hexene, 2-methyl-1-pentene, 3-methyl-1-pentene, 2-ethyl-1-butene, diisobutylene and mixtures thereof Among them, isobutylene is particularly preferred. Further, examples of the ethylenically unsaturated dicarboxylic acid include maleic acid (anhydride), itaconic acid (anhydride), citraconic acid (anhydride), and fumaric acid, but maleic anhydride is preferred. In producing a copolymer, it is also possible to use one or more of the above olefins and one or more ethylenically unsaturated dicarboxylic acids in combination, and copolymerization is possible if a poorly water-soluble state can be maintained. It is also possible to copolymerize with a third monomer such as acrylic acid or methacrylic acid.

In the present invention, poorly water-soluble salts of the above copolymers can also be used. As the poorly water-soluble salt, metal salts are preferred. The metal salt of the copolymer is preferably formed by divalent or higher valent metal ions, such as Ca", Cu", Ni, etc.
", Zn", Co"Fe", MgZ-1Mn", Sr"
, Ba'', etc., or a mixture of two or more of them, and Zn'' is particularly preferred.

Methods for adding the cement admixture according to the present invention to a cement mixture include a method of adding it to kneading water and dissolving it, and a method of adding it to a cement mixture once kneaded.

In addition, other cement additives (materials), such as air entrainment agents, anhydrite-based strength enhancers, activated silica fine powder, waterproofing materials,
Water reducing agent, drying shrinkage reducing agent, fluidizing agent, waterproofing agent, swelling agent (
It is also possible to use materials such as glass fiber, steel fiber, fly ash, and blast furnace slag.

When producing a hardened cement body to which the cement admixture according to the present invention has been added, the curing method can be a conventional method of curing a hardened cement body, or a method such as steam curing or autoclave curing can be used. good.

〔Example〕

The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

In addition, % in an example means weight %.

Example 1 A cement admixture was prepared using the following components A to C, and 0.5% based on the weight of the cement composition was added, and the following evaluations were performed.

A: Naphthalene sulfonic acid formalin high condensate (average molecular weight: 10,000) B: Melamine sulfonic acid formalin high condensate (average molecular weight: 10,000) C: Isobutylene/maleic anhydride copolymer (average molecular weight: 10,000, average Particle size: II!m) Cement compositions were prepared from the following materials, the above-mentioned cement admixtures were added, and the physical properties of each hardened cement product were measured.

(Materials used) Cement: Ordinary Portland cement specific gravity = 3.16 Fine aggregate: Local river sand specific gravity = 2.57 Coarse aggregate: Crushed stone from Takarazuka Specific gravity -2,57 Water; Tap water (mixed) Water/ Cement ratio = 53.0% Fine aggregate ratio (fine aggregate / (fine aggregate + coarse aggregate)) = 48.0
% cement amount = 320 kg/m (Preparation and evaluation of physical properties) A 100 liter tilting mixer was used to mix the cement composition, and 50 liters of the cement composition was prepared.

The physical property test for concrete is JIS A for the slump test.
1101, and the fluidity of concrete and the effect of preventing a decrease in fluidity were measured by the following method.

Changes in concrete fluidity over time are measured using a tilting mixer.
It was agitated at a constant rpm and the slump was measured for a predetermined period of time.

In addition, the compressive strength and setting time of concrete are determined by JIS
Measured in accordance with the test methods of A 1108 and ASTM C403.

The measurement results are shown in Table 1.

Example 2 A cement admixture was prepared from the A-C components used in Example 1, and the amount of cement admixture was 0.
．． The same evaluation as in Example 1 was conducted with the addition of 5%.

The results are shown in Table 2.

The weight ratio of each component in the cement admixture is A/B/C=
50/47/3, and the C component isobutylene/maleic anhydride copolymer used had various molecular weights and average particle diameters as shown in Table 2.

Example 3 A cement admixture was prepared from the components F to C used in Example 1, and a
．． The same evaluation as in Example 1 was conducted with the addition of 5%.

The results are shown in Table 3.

The weight ratio of each component in the cement admixture is A/B/C-
50/47/3, and the melamine sulfonic acid-formalin high condensates used as component B had various molecular weights as shown in Table 3.

Table 3 [Effects of the invention] From the above examples, it can be confirmed that the cement admixture of the present invention can effectively prevent the decline in workability over time without delaying the increase in concrete strength. .

Furthermore, it maintains the fluidity of concrete for a long time, and
It is also effective for applications such as tunnel construction concrete and continuous underground wall concrete that require early development of concrete strength.

Claims (1)

[Scope of Claims] 1 (A) a naphthalene sulfonic acid formalin high condensate, (B) a melamine sulfonic acid formalin high condensate having an average molecular weight of 5,000 to 100,000, and (C) an average molecular weight of 500 to 50,000, and A copolymer of an olefin and an ethylenically unsaturated dicarboxylic acid and/or a poorly water-soluble salt of the copolymer having an average particle size of 0.1 to 50 μm in a weight ratio of (A)/(B)/(C) =90~30
A cement admixture characterized in that it is blended in a range of /70 to 10/0.5 to 10.