WO2020194671A1 - Cement composition for plastering and mortar for plastering - Google Patents

Abstract

The present invention is a cement composition for plastering, the cement composition comprising at least fly ash that satisfies all of conditions (F1)-(F5) below, and being such that the fly ash content is 10-50 mass% when the total of the fly ash and the Portland cement is taken to be 100 mass%.　(F1) The Blaine specific surface area of the fly ash is 2,500-6,000 cm²/g. (F2) The mass loss of the fly ash after the fly ash is heated for 15 minutes at 975±25°C is 5 mass% or less. (F3) The SiO₂ content in the fly ash is 50 mass% or more. (F4) The sphere reduced specific surface area of particles in which iron oxide and amorphous materials are present in mixture in the fly ash is 2,800-11,000 cm²/cm³. (F5) The sphere reduced specific surface area of amorphous particles containing calcium (Ca) in the fly ash is 2,100-22,500 cm²/cm³.

Description

Plastering cement composition and plastering mortar

The present invention relates to a plastering cement composition having high workability and strength development even in a high temperature area, and a plastering mortar containing the plastering cement composition. In addition, in this specification, "high temperature" means that the annual average temperature is 25 degreeC or more.

Various plastering mortars with high workability are known as finishing materials for the surface of structures.
For example, Patent Document 1 describes a fly ash mortar containing fly ash, cement, and fine aggregate that has been pulverized and classified so as to have a particle size of 20 μm or less without damaging the spherical shape. Then, in the fly ash mortar, the replacement rate of the fly ash with respect to the cement is 10 to 30% by weight, and the total mass of the fly ash and the cement: the mass of the fine aggregate = 1: 1 to 1: 2.5. It is a surface finishing material (plastering mortar) for structures that is a ratio.
Further, Patent Document 2 describes slag having a BET specific surface area of 0.75 to 3.3 m ² / g and / or fly ash, aggregate, cement having a BET specific surface area of 1.5 to 3.3 m ² / g. And a sulfuric acid resistant water hard coating material (plastering mortar) containing a water reducing agent is described.

Japanese Unexamined Patent Publication No. 3-126652 Japanese Unexamined Patent Publication No. 2006-2488839

Plastering mortar usually contains a water retention agent to improve workability and the like. Incidentally, the water-retaining agent described in Patent Document 1 is methyl cellulose (see Examples), and the water-retaining agent described in Patent Document 2 is water-soluble cellulose such as hydroxypropyl methyl cellulose.
However, plastering mortar containing a water retention agent has a problem that workability is greatly reduced in a hot area, and since the water retention agent is generally expensive, the workability is improved even if the water retention agent is not used. High plastering mortar is required.
Therefore, an object of the present invention is for plasterers who have high workability without using a water-retaining agent, less mortar dripping when applied to a wall surface, and high strength development in a high temperature area. To provide a cement composition or the like.

Therefore, the present inventor has diligently studied a plastering cement composition or the like capable of achieving the above object, and found that a plastering cement composition containing fly ash satisfying a specific condition can achieve the above object. It was completed.
That is, the present invention is a plastering cement composition or the like having the following constitution.

[1] Contains at least fly ash and Portland cement that satisfy all of the following conditions (F1) to (F5).
A plastering cement composition having a content of 10 to 50% by mass of the fly ash, where the total of the fly ash and Portland cement is 100% by mass.
(F1) Fly ash has a specific surface area of 2500 to 6000 cm ² / g.
(F2) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5% by mass or less (F3) The content of SiO _{2 in} the fly ash is 50% by mass or more (F4) Fly The sphere-equivalent specific surface area of particles in which iron oxide and amorphous are mixed in ash is 2800 to 11000 cm ² / cm ³
(F5) The spherical specific surface area of amorphous particles containing Ca (calcium) in fly ash is 2100 to 22500 cm ² / cm ³
[2] The plastering cement composition according to the above [1], wherein the fly ash further satisfies the following conditions (F6).
(F6) The sphere-equivalent specific surface area of particles in which mullite and amorphous particles are mixed in fly ash is 1900 to 9500 cm ² / cm ³
[3] The plastering cement composition according to the above [1] or [2], wherein the fly ash further satisfies the following conditions (F7).
(F7) The sphere-equivalent specific surface area of Ca-free amorphous particles in fly ash is 2100 to 9000 cm ² / cm ³
[4] A plastering cement composition further containing blast furnace slag powder.
The plastering cement composition according to any one of [1] to [3] above, wherein the total of Portland cement, fly ash, and blast furnace slag powder is 100% by mass, and the content of blast furnace slag powder is 50% by mass or less. object.
[5] A plastering cement composition containing an inorganic powder obtained by further crushing natural rock.
The plasterer according to any one of [1] to [4] above, wherein the total of Portland cement, fly ash, blast furnace slag powder, and inorganic powder is 100% by mass, and the content of the inorganic powder is 30% by mass or less. Cement composition.
[6] A plastering cement composition containing one or more types of gypsum selected from anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum.
Portland cement, fly ash, blast furnace slag powder, inorganic powder, and the total 100 mass% of the gypsum content of the gypsum is not more than 3.0 mass% converted to SO _3, of [1] to [5] The plastering cement composition according to any one.
[7] The plastering mortar containing the cement composition for plastering according to any one of [1] to [6] above, fine aggregate, and water.

The plastering mortar of the present invention containing the plastering cement composition of the present invention has high workability in a high temperature area without using a water retaining agent, and when applied to a wall surface, the mortar drips, etc. And high strength development.

The present invention is, as described above, a plastering cement composition and a plastering mortar. First, the plastering cement composition of the present invention will be described.
1. 1. Plastering cement composition The plastering cement composition contains at least fly ash and Portland cement, and the content of the fly ash is 10 to 50% by mass with the total of the fly ash and Portland cement as 100% by mass. .. If the content of fly ash is less than 10% by mass, the workability of the plastering mortar decreases, and if it exceeds 50% by mass, the plastering mortar may sag more and the strength is exhibited. descend. The content of the fly ash is preferably 12 to 40% by mass, more preferably 14 to 35% by mass.

(I) Portland cement The Portland cement used in the present invention is derived from ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, and low heat Portland cement specified in R 5210 of Japanese Industrial Standards (hereinafter referred to as "JIS"). One or more selected species can be mentioned. Among these, the Portland cement is preferably ordinary Portland cement and / or early-strength Portland cement because it improves the strength development of plastering mortar.

(Ii) Fly ash The fly ash used in the present invention is a fly ash that satisfies all of the following conditions (F1) to (F5).
(F1) Fly ash has a specific surface area of 2500 to 6000 cm ² / g.
(F2) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5% by mass or less (F3) The content of SiO _{2 in} the fly ash is 50% by mass or more (F4) Fly The sphere-equivalent specific surface area of particles in which iron oxide and amorphous are mixed in ash is 2800 to 11000 cm ² / cm ³
(F5) The spherical specific surface area of amorphous particles containing Ca in fly ash is 2100 to 22500 cm ² / cm ³

Next, the conditions (F1) to (F5) will be described in detail.
(F1): wherein in the Blaine specific surface area of the fly ash 2500cm less than ² / g, reduces the strength development of the plastering mortar, exceeds 6000 cm ² / g, in addition to workability of plastering mortar is reduced, Blaine It is difficult to obtain fly ash with a specific surface area of more than 6000 cm ² / g. The specific surface area of the brain is preferably 2700 to 5000 cm ² / g, and more preferably 2900 to 4000 cm ² / g.

(F2): When the mass reduction rate of the fly ash exceeds 5% by mass after heating the fly ash at 975 ± 25 ° C. for 15 minutes, the strength development of the plastering mortar decreases. The mass reduction rate is preferably 1.0 to 4.5% by mass, more preferably 1.5 to 4.0% by mass, from the viewpoint of easy availability and strength development.

(F3): When the content of SiO _{2 in} the fly ash is less than 50% by mass, the strength development of the plastering mortar is lowered. The content of SiO ₂ is preferably 51 to 70% by mass, more preferably 52 to 65% by mass, from the viewpoint of easy availability and strength development.

(F4): When the sphere-equivalent specific surface area of the particles in which iron oxide and amorphous particles are mixed in the fly ash is outside the range of 2800 to 11000 cm ² / cm ³ , the workability and strength development of the plastering mortar are lowered. In addition, there is a risk of dripping, and it is difficult to obtain. The spherical specific surface area of the particles in which iron oxide and amorphous are mixed is preferably 4000 to 10000 cm ² / cm ³ , and more preferably 5000 to 10000 cm ² / cm ³ .

(F5): When the spherical specific surface area of the amorphous particles containing Ca in the fly ash is outside the range of 2100 to 22500 cm ² / cm ³ , the workability and strength development of the plastering mortar are lowered, and the strength is developed. There is a risk of dripping, and it is difficult to obtain. The spherical specific surface area of the amorphous particles containing Ca is preferably 4000 to 20000 cm ² / cm ³ , and more preferably 7000 to 20000 cm ² / cm ³ .

In addition, in order to improve the workability of plastering mortar, especially movement, elongation, and strength development, the sphere-equivalent specific surface area of particles in which mullite and amorphous particles are mixed in fly ash is preferably 1900. It is -9500 cm ² / cm ³ , more preferably 3000 9000 cm ² / cm ³ , and even more preferably 4500 9000 cm ² / cm ³ . Also. For the same reason, the spherical specific surface area of the Ca-free amorphous particles in the fly ash is preferably 2100 to 9000 cm ² / cm ³ , more preferably 3000 to 8500 cm ² / cm ³ , and even more preferably 4500. It is ~ 8500 cm ² / cm ³ .

The fly ash usually contains 5 to 25% by mass of quartz, and the lattice volume of quartz in the fly ash used in the present invention is a value obtained by using the Rietveld analysis method, preferably 113. It is 5 to 114.5Å ³ . If the lattice volume of quartz is within the above range, the fluidity and strength development of plastering mortar are further improved. The lattice volume of quartz is more preferably 113.6 to 114.4Å ³ , and even more preferably 113.7 to 114.3Å ³ . The Rietveld analysis of quartz in fly ash is based on the X-ray diffraction pattern of fly ash, for example, analysis software (Topas ver. 2.1) manufactured by Bruker, and 331161 (Quartz) as crystal structure data (ICDD number). Can be done using.
Further, the sphere-equivalent specific surface area of the quartz particles in the fly ash is preferably 1100 to 12500 cm ² / cm ³ , because it improves the workability of the plastering mortar, particularly the movement, elongation, and strength development. It is preferably 2500 to 10000 cm ² / cm ³ , and more preferably 4000 to 10000 cm ² / cm ³ .

The fly ash particles undergo the following steps (1) to (4) to obtain (i) particles in which iron oxide and amorphous are mixed, (ii) particles in which mulite and amorphous are mixed, and (iii) Ca. It is classified into five types: amorphous particles that do not contain, (iv) amorphous particles that contain Ca, and (v) quartz particles.
(1) Sample Preparation Step This step is a step of mixing fly ash and resin to prepare a cured test piece. By dispersing the fly ash in the resin, the fly ash particles do not overlap, and each particle can be accurately extracted and its characteristic value can be measured at the time of particle analysis described later.
The resin may be any resin that shrinks less in the curing process and does not crack, and examples thereof include epoxy resins, acrylic resins, polyester resins, and methacrylic resins. The mixing ratio of the resin is preferably 0.8 to 4 in terms of volume ratio with respect to fly ash. Within this range, a plurality of particles can be dispersed without contacting each other, and polishing described later can be performed to obtain cut surfaces of many particles.

Next, the imaging surface of the cured test piece is polished. If the image surface is uneven or the cut surface of the particles does not appear sufficiently, the particle size and shape of the particles cannot be measured accurately, and the accuracy of the particle analysis described later is lowered.
The polishing device for the imaging surface of the test piece is not particularly limited, and a commonly used polishing device can be used. The abrasive used in the polishing step is not particularly limited, and examples thereof include a silicon carbide abrasive, a boron carbide abrasive, a diamond paste, and an alumina powder. Further, the polishing is preferably buffing using alumina powder having a diameter of 0.3 to 3 μm or the like as an abrasive, and since there are few irregularities on the image surface, a cross section using an argon ion beam is more preferable. Polishing with a polisher.

Finally, a thin-film deposition film is formed on the surface of the test piece whose imaging surface has been polished to impart conductivity to the test piece. In the particle analysis described later, the test piece is irradiated with an electron beam, but since fly ash and resin do not have conductivity, the surface of the test piece is charged when a reflected electron image is obtained without forming a vapor deposition film on the test piece. However, an accurate reflected electron image cannot be obtained. Therefore, in order to obtain an accurate reflected electron image, a thin-film film having conductivity is formed on the surface of the test piece.
The vapor-deposited film is not particularly limited as long as it can impart conductivity to the surface of the test piece, and examples thereof include a vapor-deposited film of carbon, platinum-palladium, gold, and the like. Further, the method for forming the thin-film deposition film is not particularly limited, and a known method can be used.

(2) Fly ash particle analysis step The step is a step of first acquiring a backscattered electron image (BSE) and a chemical composition of the test piece prepared in the sample preparation step using an electron microscope. Since the electron microscope only needs to be able to measure the reflected electron image and the chemical composition of a minute region, a scanning electron microscope (SEM), an electron probe microanalyzer (EPMA), or the like can be used. The reflected electron image is displayed brighter as the average atomic number of the elements constituting the region is larger. Examples of the chemical composition acquisition device include a wavelength dispersive X-ray spectroscope (WDS) and an energy dispersive X-ray spectroscope (EDS), but energy dispersive X-rays are preferable because the chemical composition can be acquired in a short time. It is a spectroscope (EDS).
In order to acquire a high-resolution reflected electron image, it is preferable to set the acceleration voltage to about 10 to 15 keV, the irradiation current to about 200 to 1000 pA, and the observation magnification to about 500 to 2000 times.

In performing the particle analysis of fly ash, the reflected electron image is obtained from the test piece of fly ash, and the fly ash particles and the reflected electron image of the resin are compared with each other visually and the luminance histogram is referred to. Determine the threshold of brightness that can separate the resin from. Then, using the threshold value, binarization processing is performed to extract fly ash particles. For the extracted fly ash particles, a geometric measurement value is measured for each particle. Examples of this geometric measurement value include a circularity coefficient, a circle-equivalent diameter (diameter of a circle having an area equal to the cross-sectional area of the particle), an aspect ratio, and the like.

(3) Chemical analysis step of fly ash particles The step is a step of chemically analyzing fly ash particles to grasp the chemical composition of fly ash. In order to quickly obtain the chemical composition of fly ash with high accuracy using an energy-dispersed X-ray spectrometer, the accelerating voltage is about 10 to 15 keV, the irradiation current is about 200 to 1000 pA, and the analysis time is one analysis. Set to 5-10 seconds per dot. The diameter of the analysis area is preferably the entire individual particles.
The order of the chemical analysis and the measurement of the geometrically measured value does not matter. The number of fly ash particles to be measured is preferably 1000 or more, more preferably 2000 or more, in order to reduce the measurement error between the chemical analysis and the geometric measurement value. The number of X-ray counts per particle is preferably 5000 counts or more, more preferably 10000 counts or more, and further preferably 100,000 counts or more. For the convenience of image processing in particle analysis, the divided particles at the edge of the image are joined together in the analysis and counted as one particle. In particle analysis, the area and chemical composition of particles are acquired as characters for each particle.

(4) Classification step of fly ash particles In this step, (i) iron oxide and amorphous are mixed using the above chemical composition of fly ash particles and the threshold of the chemical composition of fly ash particles shown in Table 1. Either (ii) particles in which mulite and amorphous are mixed, (iii) amorphous particles without Ca, (iv) amorphous particles containing Ca, and (v) quartz particles. This is the process of classifying into classes. Extraction of fly ash particles, chemical analysis, and calculation of geometric measurement values for classification can be performed automatically by using the particle analysis software attached to the electron microscope, which is convenient.

The sphere-equivalent specific surface area is calculated according to the following.
First, for each fly ash particle classified into each of the above classes, assuming that all the particles are spheres, the circle equivalent diameter D is calculated from the cross section S of the fly ash particles using the following equation (1).

Next, the surface area A and volume V of the particles when the particles are assumed to be spheres are calculated from the calculated equivalent circle diameters using the equations (2) and (3).

Finally, to calculate the sum of the total surface area and the volume of fly ash particles in each class to calculate the spherical equivalent specific surface area S _A using (4).

In order to improve the workability and strength development of plastering mortar and suppress sagging (dripping), (Na ₂ O + 0.658 × K ₂ O) / (MgO + SO ₃ + TiO ₂ + P ₂ O) in the fly ash The mass ratio of ₅ + MnO) is preferably 0.2 to 1.0, more preferably 0.25 to 0.8, still more preferably 0.28 to 0.7, and particularly preferably 0.3 to 0.6. Is.
Further, in order to improve the workability and strength development of the plastering mortar, the fly ash has a compaction density of 1.0 to 1.5 cm ³ / g calculated by measuring by the following method. more preferably 1.05 ~ 1.45cm ³ / g, more preferably from 1.1 ~ 1.4cm ³ / g.
[Measurement method of compaction density]
Using a powder tester PT-D manufactured by Hosokawa Micron, the fly ash is filled in a 100 cm ³ cup, the cup is tapped 180 times in 180 seconds, and then the mass of the fly ash compacted in the cup is measured. Measure and calculate the compaction density. The volume (denominator) used in the density calculation formula is the volume of the cup.

Furthermore, the plastering cement composition of the present invention may further contain blast furnace slag powder in order to improve the long-term strength development of the plastering mortar.
When the plastering cement composition of the present invention contains blast furnace slag powder, the content of the blast furnace slag powder is preferably 50% by mass or less, with the total of fly ash, Portland cement, and blast furnace slag powder being 100% by mass. It is preferably 45% by mass or less. If the amount of blast furnace slag powder exceeds 50% by mass, the effect of improving the long-term strength development of plastering mortar is reduced.
Incidentally, the Blaine specific surface area of the blast furnace slag powder, for improved strength development of plastering mortar, preferably 3000 ~ 6000cm ² / g, more preferably 3300 ~ 5000cm ² / g.

The plastering cement composition of the present invention is an inorganic powder obtained by crushing natural rocks such as limestone powder and silica stone powder in order to improve the workability, particularly cutting and elongation of plastering mortar. May include. Among these, the preferable inorganic powder is limestone powder.
When the plastering cement composition of the present invention contains an inorganic powder, the content of the inorganic powder is preferably 30% by mass or less, with the total of fly ash, Portland cement, blast furnace slag powder, and the inorganic powder being 100% by mass. More preferably, it is 25% by mass or less. If the amount of the inorganic powder exceeds 30% by mass, the strength development of the plastering mortar is lowered, and there is a risk that dripping will increase.
The brain specific surface area of the inorganic powder is preferably 3000 to 10000 cm ² / g, more preferably 4000 to 8000 cm ² / g in order to improve the workability and strength development of the plastering mortar.

The plastering cement composition of the present invention may further contain one or more gypsum selected from anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum in order to improve the strength development of the plastering mortar.
If plastering cement composition of the present invention comprises gypsum, fly ash, Portland cement, blast furnace slag powder, inorganic powder, and gypsum total of 100% by mass, the content of gypsum 3.0 mass converted to SO ₃ % Or less. If the gypsum content exceeds 3.0% by mass in terms of SO ₃ , the fluidity of the plastering mortar will decrease. Incidentally, the content of the gypsum is converted to SO _3, 2.7 wt% and more preferably less, more preferably 2.5 wt% or less, particularly preferably 2.3 mass% or less.
The gypsum is preferably anhydrous gypsum or dihydrate gypsum in order to improve the strength development of plastering mortar. The specific surface area of gypsum is preferably 3000 to 15000 cm ² / g, and more preferably 3500 to 13000 cm ² / g in order to improve the strength development.

2. 2. Plastering mortar Next, the plastering mortar of the present invention will be described.
The plastering mortar of the present invention includes the plastering cement composition, fine aggregate, and water.
Examples of the fine aggregate include river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, or a mixture thereof.
The amount of the fine aggregate to be blended is preferably 150 to 800 parts by mass, more preferably 175 to 750 parts by mass, still more preferably 200 to 500 parts by mass, particularly preferably 200 parts by mass, based on 100 parts by mass of the plastering cement composition. Is 200 to 300 parts by mass. When the blending amount is 150 parts by mass or more, the strength development of the plastering mortar is improved, and when it is 800 parts by mass or less, the workability of the plastering mortar is improved.

Tap water etc. can be used as water. The amount of water to be blended is preferably 40 to 125 parts by mass, more preferably 45 to 120 parts by mass, still more preferably 50 to 100 parts by mass, and particularly preferably 50 to 80 parts by mass with respect to 100 parts by mass of the plastering cement composition. It is a mass part. When the amount is 40 parts by mass or more, the workability of the plastering mortar is improved, and when the amount is 125 parts by mass or less, the strength development of the plastering mortar is improved.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.
1. 1. Materials used The various materials used in the test are shown below.
(1) Ordinary Portoland Cement Brain The specific surface area is 3310 cm ² / g and is manufactured by Taiheiyo Cement.
(2) Dihydrate gypsum brain The specific surface area is 8250 cm ² / g, manufactured by Sumitomo Metals.
(3) Blast furnace slag powder Brain The specific surface area is 4300 cm ² / g and is manufactured by DC Co., Ltd.
(4) Limestone powder Brain The specific surface area is 6500 cm ² / g and is manufactured by Yuko Mining Co., Ltd.
(5) Fine aggregate No. 5 silica sand.
(6) Water Tap water.
The characteristics of the fly ash (FA) used in the test are shown in Tables 2 and 3. FA1 to 7 satisfy all of the above conditions (F1) to (F5), but FA8 to 12 do not satisfy any of these conditions. Further, FA1 does not satisfy the condition of (F6), FA2 does not satisfy the condition of (F7), but FA3 to 6 satisfy both the conditions of (F6) and (F7). Further, the spherical specific surface area of the quartz particles in FA7 is out of the range of 1100 to 12500 cm ² / cm ³ .

2. 2. Production of plastering cement composition Fly ash (FA), cement (C), optional components limestone powder (LS), blast furnace slag powder (BS), and gypsum powder (GG) are shown in Table 4. A cement composition for plastering was produced by mixing according to the formulation of. In Table 4 GG is a value converted to SO _3.

2. 2. Production of plastering mortar At an environmental temperature (ambient temperature) of 27 ° C., 10 kg of the cement composition and 20 kg of silica sand were put into a bread-type mortar mixer (manufactured by Magellar) and kneaded for 1 minute. Next, kneading was carried out for 1 minute while adding 4.0 kg of water corresponding to about 80% of the total amount of water. After this kneading, the kneaded material adhering to the side wall in the mixer was scraped off and kneaded for 3 minutes while adding 1.1 kg of water corresponding to about 20% by mass of the total amount of water to obtain a plastering mortar.

2. 2. Test (A) Workability evaluation test At an environmental temperature of 27 ° C., a mortar plate with a height of 910 mm and a width of 1820 mm, which was installed so as to extend in the vertical direction, was installed in the same manner and had the same dimensions. The plastering mortar was applied to each surface of the lightweight mortar wall so as to have a thickness of about 2 cm, and the following evaluation was performed.
(1) Evaluation of Difficulty of Dripping of Mortar After applying the mortar to the above-mentioned surface, the mortar was allowed to stand at 27 ° C. for 1 hour. After standing, it was evaluated whether the applied plastering mortar did not drip or peeled off.
(2) Evaluation of movement of mortar When the mortar was applied to the above-mentioned surface and the surface of the mortar was smoothed with a trowel, the difficulty of movement of the mortar around the smoothed area was evaluated. In the evaluation of movement, if the mortar around the smoothed area is difficult to move (calm), the evaluation is high.
(3) Evaluation of Elongation of Mortar When the mortar was applied to the above-mentioned surface, it was evaluated whether or not the resistance of the mortar was low and the mortar could be easily elongated.
(4) Evaluation of running out of iron After applying the mortar to the above-mentioned surface, it was evaluated whether or not the plastering mortar was difficult to adhere to the iron when the iron was separated from the coated surface.
Each of the above evaluations is performed by a numerical value from 0 to 5.5, and the larger the numerical value, the higher the evaluation.
In Table 5, the difficulty of mortar sagging is indicated by "sagging", the movement of mortar is indicated by "movement", the elongation of mortar is indicated by "elongation", and the iron breakage is indicated by "cut".
(B) Compressive strength test The compressive strength at 28 days of age was measured according to JIS R 5201. The results are shown in Table 5.

As shown in Table 5, the mortars (Examples 1 to 16) using the cement composition for plastering of the present invention are highly evaluated for movement, elongation, and cutting at an environmental temperature of 27 ° C., and have excellent workability and a wall surface. There is little sagging after application to, and the strength development is high.
On the other hand, the mortars using the cement compositions of Comparative Examples 1 to 8 had low evaluation of movement, elongation, and cutting at an environmental temperature of 27 ° C. and were inferior in workability, and dripping occurred after being applied to the wall surface. In addition, the strength development is low.

Claims (7)

1. It contains at least fly ash and Portland cement that satisfy all of the following conditions (F1) to (F5).
   A plastering cement composition having a content of 10 to 50% by mass of the fly ash, where the total of the fly ash and Portland cement is 100% by mass.
   (F1) Fly ash has a specific surface area of 2500 to 6000 cm ² / g.
   (F2) The mass reduction rate of fly ash after heating the fly ash at 975 ± 25 ° C. for 15 minutes is 5% by mass or less (F3) The content of SiO _{2 in} the fly ash is 50% by mass or more (F4) Fly The sphere-equivalent specific surface area of particles in which iron oxide and amorphous are mixed in ash is 2800 to 11000 cm ² / cm ³
   (F5) The spherical specific surface area of amorphous particles containing Ca (calcium) in fly ash is 2100 to 22500 cm ² / cm ³
2. The plastering cement composition according to claim 1, wherein the fly ash further satisfies the following condition (F6).
   (F6) The sphere-equivalent specific surface area of particles in which mullite and amorphous particles are mixed in fly ash is 1900 to 9500 cm ² / cm ³
3. The plastering cement composition according to claim 1 or 2, wherein the fly ash further satisfies the following condition (F7).
   (F7) The sphere-equivalent specific surface area of Ca-free amorphous particles in fly ash is 2100 to 9000 cm ² / cm ³
4. A plastering cement composition containing blast furnace slag powder.
   The plastering cement composition according to any one of claims 1 to 3, wherein the total of Portland cement, fly ash, and blast furnace slag powder is 100% by mass, and the content of blast furnace slag powder is 50% by mass or less. ..
5. Furthermore, it is a plastering cement composition containing an inorganic powder obtained by crushing natural rock.
   The plastering cement according to any one of claims 1 to 4, wherein the total of Portland cement, fly ash, blast furnace slag powder, and inorganic powder is 100% by mass, and the content of the inorganic powder is 30% by mass or less. Composition.
6. A plastering cement composition containing one or more types of gypsum selected from anhydrous gypsum, semi-hydrated gypsum, and dihydrate gypsum.
   Portland cement, fly ash, blast furnace slag powder, inorganic powder, and gypsum total of 100% by mass, the content of the gypsum is not more than 3.0 mass% converted to SO _3, any one of claims 1 to 5, 1 The cement composition for plastering according to the section.
7. The plastering mortar containing the cement composition for plastering, fine aggregate, and water according to any one of claims 1 to 6.