JP4784369B2 - Cement composition with improved coating workability - Google Patents

Description

The present invention relates to a cement composition suitable for preparing a mortar having good releasability and water retention suitable for formation of a good construction finished surface and having no water floating.

The mortar coating finish on the concrete surface is often used because it is easy to construct and economical. The mortar coating finishing method is a method in which Portland cement and sand are used as materials to be used, and cement mortar to which an appropriate amount of water is added is applied to the concrete surface.

As a method for improving smoothness and glossiness by improving the roughness of the mortar finish surface, Patent Document 1 discloses a cement composition in which oligosaccharide or starch sugar is added to cement as a film forming agent. .

As a method for preventing bleeding and material separation without lowering the fluidity, without delaying the setting time at low temperature, without increasing the entrained air, Patent Document 2 discloses that an ether bond is added to the cement additive. A cement composition using a cross-linked starch having a swelling degree of 2 to 8% by weight in a saturated calcium hydroxide solution is disclosed.

JP-A-6-92705 JP-A-8-26803

In the mortar coating finishing method by plastering, a method is generally employed in which a mortar is primed on a wall surface or a floor surface, and then a smooth surface is finished by pressing a heel.
The present invention assumes that the plasterer will perform a two-step work of a presser foot that uses a scissors to prime the wall or floor surface with a mortar and then finishes it again to a smooth surface using the scissors. An object of the present invention is to provide a cement composition capable of obtaining excellent mortar coating workability and an excellent mortar finish.

The present inventor uses a combination of a specific water retention agent and a thickener for cement and fine aggregate, and imparts appropriate water retention and proper mortar viscosity in the process of priming the mortar. It is possible to form a surface state with fine irregularities that is suitable for the next finishing work, and also has a good finish on the mortar finished surface even in the process of finishing pressering work. The present invention was completed by finding that a smooth finished surface was obtained, no water floated from the surface of the finished surface, and good glazing workability and an excellent mortar finished surface were obtained.

That is, the cement composition according to the present invention is a modified starch obtained by processing a natural polysaccharide containing cement, fine aggregate, a water retention agent and a thickening agent, and the water retention agent includes amylose and amylopectin, and 100 parts by mass of cement. Is a cement composition characterized in that the water retention agent is 0.02 to 0.18 parts by mass.
Further, the cement composition according to the present invention is characterized in that the fine aggregate is 50 to 200 parts by mass and the thickener is 0.02 to 0.18 parts by mass with respect to 100 parts by mass of the cement. It is a composition.

The preferable aspect of the cement composition of this invention is shown, These can be combined multiplely.
1) The thickener is a methylcellulose thickener.
2) The cement composition further includes at least one selected from an expanding material, a sliding aggregate, and a lightweight aggregate, and used for the cross-sectional repair of concrete.
3) A mortar obtained by kneading a cement composition and water.
4) A cured product obtained by curing a blend of cement composition and water.

The cement composition of the present invention can be obtained by using a combination of a water retention agent and a thickening agent in cement and imparting appropriate water retention and proper mortar viscosity in the course of roughing mortar. A smooth surface finish that can form a surface condition with fine irregularities suitable for the next finishing work, and also has a good grip on the mortar finish surface even during the finishing work. A surface is obtained, there is no water floating from the surface of the finished surface, and a good mortar finish and an excellent mortar finished surface can be obtained.

In the cement composition of the present invention, the blending ratio of cement, fine aggregate, water retention agent and thickener can be appropriately selected. Preferably, the fine aggregate is 50 to 200 parts by mass with respect to 100 parts by mass of cement. More preferably, it contains 52 to 180 parts by mass, more preferably 54 to 160 parts by mass, and particularly preferably 55 to 150 parts by mass, and the water retention agent is 0.02 to 0.18 parts by mass, and more preferably 0.02 to 0.0. 15 parts by mass, more preferably 0.025 to 0.12 parts by mass, particularly preferably 0.03 to 0.12 parts by mass, and the thickener is 0.02 to 0.18 parts by mass, more preferably 0. 0.02 to 0.15 parts by mass, more preferably 0.025 to 0.12 parts by mass, and particularly preferably 0.03 to 0.12 parts by mass.
If the blending ratio of the water retention agent and the thickener exceeds 0.18 parts by mass, the iron releasability at the time of undercoating and the iron holding ability of the finish are deteriorated.

  In particular, the blending amount of fine aggregate, water retention agent and thickener is within the above range, which provides an excellent balance between water retention and mortar viscosity, and provides a cured mortar with excellent separation properties and surface properties.

The cement used in the cement composition of the present invention is not particularly limited, and portland cement such as ordinary Portland cement, early-strength Portland cement, medium heat Portland cement, low heat Portland cement, blast furnace cement, fly ash cement, etc. Mixed cement can be used.

As the fine aggregate used in the present invention, sand such as quartz sand, river sand, sea sand, mountain sand, land sand, cryogenic stone, charcoal cal, etc. can be used, and the particle size of the fine aggregate is preferably 0.05 to 3.5 mm, more preferably 0.075 to 2 mm, particularly preferably 0.075 to 1.5 mm can be preferably used.

As the water retention agent used in the present invention, it is preferable to use natural polysaccharide-based modified starch containing amylose and amylopectin, which are mainly made of potato and tapioca.
The water retention agent suitably used in the present invention is a natural polysaccharide-based modified starch mainly made of potato, tapioca, etc., and has a linear structure of amylose and a branched structure of amylopectin in the molecular structure. The polymerization degree is preferably in the range of 1800 to 7000, more preferably 2000 to 6500, particularly preferably 2200 to 6000.
The water retention agent used in the present invention is a natural polysaccharide-based modified starch, and its lipid content in the dry state is preferably 0.3% or less, more preferably 0.25% or less, particularly preferably. Those having a lipid content of more than 0.5% such as corn starch and wheat starch are not preferred as the water retention agent of the present invention.
By using the above natural polysaccharide-based modified starch as a water-retaining agent, when the work surface is undercoated, the surface of the undercoat surface has a moderately uneven surface and maintains a moisture state suitable for subsequent finishing operations. Therefore, a smooth finished surface can be formed by finishing the presser foot.

As the thickener used in the present invention, cellulose-based, protein-based, latex-based, water-soluble polymer-based, and the like can be used, and one or two or more types can be added as long as the characteristics of the present invention are not impaired. it can. In the present invention, a methylcellulose thickener can be particularly preferably used.
By using a thickener, the generation of bleeding water can be significantly suppressed, particularly when thick coating is applied to the floor surface.

The cement composition of the present invention may contain, in addition to the fine aggregate, water retention agent, and thickener, at least one selected from an expanding material, a sliding aggregate, and a lightweight aggregate as necessary. preferable.

  When the mortar of the cement composition of the present invention is applied to a wall surface or a floor surface, it is necessary to have a non-shrinkable and very small volume change during curing, but in the present invention, by adding an expansion material The volume change that occurs when the mortar is cured can be suppressed.

  As the expanding material, it is preferable to use an expanding material such as calcium sulfoaluminate-based, lime-gypsum-based, or lime-based, and it can be used as one kind or a mixture of two or more kinds. It is particularly preferable to use a lime-gypsum-based expansion material.

  The amount of the expansion material is preferably 1 to 20 parts by mass, more preferably 1.5 to 15 parts by mass, and more preferably 2 to 12 parts by mass with respect to 100 parts by mass of the cement. In particular, it is preferable to use 3 to 10 parts by mass.

In the cement composition of the present invention, the workability of glazing and the finish of the mortar surface are important factors, and work such as detachment is achieved by blending a smooth aggregate and / or a lightweight aggregate having an effect of improving workability. And the smoothness of the finished surface can be improved.

It is considered that the sliding aggregate has an effect of moderately reducing the friction between the mortar applied to the wall surface or the floor surface in the glazing operation and the heel surface.
As the sliding aggregate, soft inorganic components such as wax, talc, talc, and pyrophyllite can be preferably used, and the particle size of the sliding aggregate is preferably 0.05 to 1500 μm, more preferably 0.8. One having a thickness of 1 to 1000 μm, particularly preferably 0.15 to 500 μm can be preferably used.
The amount of the lubricant aggregate is preferably 1 to 10 parts by weight, more preferably 2 to 9 parts by weight, and particularly preferably 3 to 8 parts by weight with respect to 100 parts by weight of cement. Is appropriate, and the effect of improving the coating efficiency is high and preferable.

In the cement composition of the present invention, by blending a lightweight aggregate, the shape of the lightweight aggregate itself partially collapses in the process of wrinkling and pressing, so that a part of the absorbed water is mortar. Opening to the surface improves the slipping of the work rod, so that it is possible to obtain an effect of improving workability such as releasability and smoothness of the finished surface.
As the lightweight aggregate, pearlite obtained by heating and foaming obsidian or pearlite, and lightweight aggregate obtained by heating and foaming coal gasification slag can be suitably used. It is preferable because workability can be obtained.
The particle size of the lightweight aggregate used in the present invention is preferably 0.1 to 5 mm, more preferably 0.2 to 4 mm, and particularly preferably 0.3 to 3 mm.
The blending amount of the lightweight aggregate is preferably 50 to 200 liters, more preferably 80 to 180 liters, and particularly preferably 100 to 150 liters with respect to 100 parts by mass of cement to obtain a good glazing workability. Can do.

In the cement composition of the present invention, it is preferable to use a sliding aggregate and a lightweight aggregate together. This is synergistic between the effects of slippery aggregates, that is, the effect of moderately reducing the friction between the mortar and the heel surface, and the effect of releasing a part of the water absorbed by the lightweight aggregate to the mortar surface. Therefore, it is possible to obtain better workability such as separation and smoothness of the finished surface than using each of them independently.

The cement composition of the present invention can be used in addition to fine aggregates, water retention agents and thickeners, as long as it does not impair the properties of the present invention, if necessary, a fluidizing agent, a setting speed adjusting agent, a polymer emulsion, an organic Components such as short fibers can be blended.

  The cement composition of the present invention can adjust the fluidity, water retention amount, glazing workability, and the like by adjusting the amount of water added.

  The amount of water added is preferably 20 to 50 parts by mass, more preferably 23 to 45 parts by mass, more preferably 25 to 42 parts by mass, and particularly preferably 25 to 40 parts by mass with respect to 100 parts by mass of the cement composition. Are preferably used.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited by the following examples.

(Characteristic evaluation method)
1) Flow value (mm):
According to the flow test of the physical test method of JIS R 5201 cement.
2) Water retention (mm):
5A filter paper (diameter 11 cm) specified in JIS P 3801 is placed on a polished plate glass with a thickness of 5 mm, and a ring mold (made of brass, inner diameter 50 mm, height 10 mm, thickness 3 mm) is installed at the center. The kneaded mortar is smoothly packed into the mold. Immediately after that, a filter paper and a glass plate are put on the upper part of the ring form and turned upside down to stand still. Measure the length of the water spread to the upper filter paper after 5 minutes and the length in the direction perpendicular to the direction up to 1 mm using a scale, and determine the average length of the measured values in the two directions as water retention. To do.
3) Surface state of the undercoat (unevenness state) and surface state of the finished heel presser (smoothness):
Take the mortar that has been kneaded on a iron board, rub it against the concrete wall and floor using a plastering iron with sufficient iron pressure (ground rub), and blend the groundwork with the cement composition, then undercoat Is applied once to a thickness of 10 mm, and the uneven state of the mortar surface is observed.
Next, the moisture (watering) state of the undercoated mortar surface is confirmed, and the surface of the undercoated mortar is pressed with a finishing trowel to confirm the finished smooth state.
4) Water float on the surface after painting:
Using a mechanical kneader of JIS R 5201 cement physical test method, 1 kg of a sample is put into a kneading bowl, and the kneading water is poured in such an amount that an appropriate flow value can be obtained while starting the kneader for 3 minutes. mix. After the kneaded mortar surface is lightly leveled, it is allowed to stand in a kneading bowl and the presence or absence of water floating (bleeding water) on the mortar surface after 1 hour is confirmed.
5) Separation (workability):
The kneaded mortar is evaluated by the degree of adhesion and the degree of adhesion between the mortar and the trowel when it is applied to the wall and floor using a plastering iron. High-viscosity and sticky mortars are difficult to separate and workability is poor.

The following materials were used.
1) Cement:
Portland cement (Ube ordinary Portland cement, Blaine specific surface area 3300 cm ² / g).
2) Fine aggregate:
・ Silica sand: No. 7 silica sand (manufactured by Ashiya, particle size: <0.3 mm, average particle size = 0.075 mm)
・ Samsui: Made by Hitachi Sekisui.
・ Charcoal Cal: Made by Hitachi Suisui
3) Water retention agent:
-Natural polysaccharide water retaining agent (ATECEL301 manufactured by AVEBE).
4) Thickener:
Metros thickener (SB30004YP manufactured by Shin-Etsu Chemical Co., Ltd.)
5) Expansion material:
-Lime-gypsum-based expansion material (Pacific Gypcal made by Taiheiyo Cement).
6) Lubricant aggregate and wax stone (manufactured by Saitama Mining Co., Ltd., grain size 0.3-100 μm)
7) Lightweight aggregate, perlite a (6F, manufactured by Toho Perlite).
-Perlite b (TM3 manufactured by Toho Perlite).
8) Organic short fibers:
-Vinylon short fiber (Fiber length: 6 mm, manufactured by Kuraray Co., Ltd.).

[Examples 1 to 4 and Comparative Examples 1 to 4]
The components shown in Table 1 were mixed using a rocking mixer to obtain a cement composition composed of cement, fine aggregate and admixture.

Under the conditions of a temperature of 20 ° C. and a relative humidity of 65%, kneading water shown in Table 1 was added to 100 parts by mass of the cement composition, and kneaded at a low speed for 3 minutes using a Hobart mixer to prepare a kneaded product.
Table 1 shows the results of evaluating the flow value, water retention, surface roughness after application, surface water float after application, and wrinkle separation (workability) of the obtained kneaded product.

  In the case of Comparative Example 1 which does not contain a water retention agent and a thickener, the water retention of the mortar is poor, and as shown in FIG. Status). Subsequently, when finishing the heel presser, the heel sticked too much to the surface of the undercoat mortar during the heel pressering process, so that the glazing workability was remarkably lowered and a smooth surface state could not be formed.

  In the case of Comparative Example 3 in which only the water retention agent is added and no thickening agent is used, improvement in water retention due to the synergistic effect of the water retention agent and the thickening agent cannot be obtained, and water floating from the mortar surface is observed. .

  In the case of Comparative Example 4 in which only the thickener is added, the surface condition of the undercoat mortar after mortar application is less uneven (thin state) as shown in FIG. It is difficult to obtain good workability and good finish surface condition.

  In the case of Example 4 in which a water retention agent and a thickener were added in an appropriate range, the water retention of the mortar is good, and the surface of the undercoat after mortar application is about 1.5 to 3 mm as shown in FIG. A large number of minute irregularities were formed (coarse state). Thus, when many unevenness | corrugations are formed in the surface of undercoat mortar, in the next wrinkle pressing operation, while being able to obtain a good releasability, a smooth finished surface can be formed. Furthermore, no water floating from the surface of the mortar was observed, and good glazing workability was obtained through the two-stage work of mortar construction undercoat to finishing trowel presser.

  Also about Examples 1-3 which added the water retention agent and the thickener in the appropriate range, the water retention of mortar was favorable and many surface irregularities after mortar application were seen like Example 4. Further, no water floating on the surface of the mortar was observed, and good glazing workability was obtained in two stages of mortar undercoating to finishing heel presser.

Moreover, when Examples 1-4 containing a water retention agent and a thickener and the comparative example 1 which does not contain a water retention agent and a thickener are compared, Examples 1-4 are kneaded 1 hour later, Changes in flow value and water retention are very small.
In the case of Comparative Example 2 in which a water retention agent and a thickening agent are added beyond the appropriate range, the water retention of the mortar is further improved, but the viscosity of the mortar becomes too high and the separation property during construction is extremely deteriorated. is doing.

The state in which the mortar prepared under the blending conditions of Example 4 was primed on the concrete surface using a cocoon was observed. (Surface condition: Unevenness, releasability: good) The state which primed the mortar prepared on the compounding conditions of the comparative example 4 on the concrete surface using the coffin is observed. (Surface condition: few irregularities, releasability: not good) The state in which the mortar prepared under the blending conditions of Comparative Example 1 was undercoated on the concrete surface using a cocoon was observed. (Surface condition: Very little unevenness, releasability: bad)

Claims (6)

Including cement, fine aggregate, water retention agent, thickener, expansion material, slipping aggregate, and lightweight aggregate ,
The water retention agent is a modified starch obtained by processing a natural polysaccharide containing amylose and amylopectin,
The degree of polymerization of the water retention agent is in the range of 2000 to 6500,
The lipid content in the dry state of the water retention agent is 0.3% or less,
The water retention agent to the cement 100 parts by a 0.02 to 0.18 parts by weight,
The thickener is a methylcellulose thickener,
Cement composition characterized by being 0.02-0.18 parts by mass of the thickener with respect to 100 parts by mass of cement.   The cement composition according to claim 1, wherein the fine aggregate is 50 to 200 parts by mass with respect to 100 parts by mass of cement.   The expansion material is a lime-gypsum expansion material,
The expansion material is 3 to 10 parts by mass with respect to 100 parts by mass of cement.
The cement composition according to claim 1 or 2, characterized by the above-mentioned.   The slip aggregate includes at least one component selected from wax, talc, talc, and pyrophyllite;
1 to 10 parts by mass of the above-mentioned sliding aggregate with respect to 100 parts by mass of cement
The cement composition according to any one of claims 1 to 3, wherein The cement composition according to any one of claims 1 to 4, wherein a particle size of the slip aggregate is 0.15 to 500 µm.   The cement composition according to any one of claims 1 to 5, wherein the lightweight aggregate is pearlite, and the particle size of the lightweight aggregate is 0.1 to 5 mm.

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