JP2000239075A - Cured cement product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lightweight cured cement product (mortar, concrete) with a high compressive strength, slight variance in the distribution of its specific gravity and mechanical strength, and smooth and beautiful finished surface. SOLUTION: This cured cement product is made from cement, ultra- lightweight fine aggregate <1.2 mm in particle size and >=0.5 but <1 in absolute dry specific gravity, and foamed beads each <=0.6 mm in size, This cured cement product is obtained by curing and solidifying an aqueous admixture of a cement composition containing 5-40 vol.% of the foamed beads based on the total volume of the foamed beads and the ultra-lightweight fine aggregate so as to include 6-10 vol.% of air in the final product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement-cultured organism such as concrete, which is lightweight, has high strength, has a small variation in specific gravity and strength distribution, and has an excellent surface appearance.

[0002]

2. Description of the Related Art In recent years, mortars or concretes used for buildings with increasing heights of buildings have been required to be lighter and have higher strength from the viewpoint of earthquake resistance, workability, economy and the like. Concrete is targeted to have an air-dry specific gravity of 1.5 or less and a compressive strength of 30 MPa or more, and research is being conducted to realize this.

[0003] As a method for reducing the weight of mortar or concrete (hereinafter sometimes referred to as concrete) consisting of a paste portion (a binder) and an aggregate, conventionally, air bubbles are introduced into the paste portion to reduce the specific gravity of the paste portion. The method of lowering is common. Specifically, since the paste portion is composed of cement, water or further inorganic fine powder, this water-cement ratio is increased to introduce bubbles derived from water, or to contain bubbles by a foaming agent or the like. I just need.

However, when bubbles are introduced into the paste portion,
Concrete compressive strength is greatly reduced. For example, when the water-cement ratio is increased (the cement-water ratio is reduced) to reduce the weight, a concrete composition that provides a water-cement ratio of 45% by weight, and a compressive strength of about 1.53 in air-dry specific gravity and about 30 MPa is obtained. However, if the air-dry specific gravity of concrete is reduced to about 1.48 by introducing air bubbles only by changing the water cement ratio, the compressive strength becomes 24 MPa.
To a degree.

[0005] On the other hand, a method of reducing the weight of aggregate has been conventionally performed. However, in general, the lighter the aggregate, the lower the strength. The lighter aggregate that can be used for high-strength concrete is a coarse aggregate having a particle size of 5 mm or more and a bone-dry specific gravity of 1.2.
~ 1.3, fine aggregate with particle size less than 5mm
About 7 are widely used. When trying to obtain high-strength concrete with a compressive strength of about 30 MPa using such a lightweight aggregate, the air-drying specific gravity of the concrete could be reduced only to about 1.5 because the paste portion could not be reduced in weight. .

[0006] On the other hand, in recent years, the development of ultra-light aggregates having a specific gravity of less than 1 has been promoted, and their use has been proposed.
For example, JP-A-4-270154, JP-A-4-4-2
Japanese Patent No. 70155 proposes a concrete composition in which cement is mixed with an ultralight coarse aggregate having a specific gravity of less than 0.9 and an ultralight fine aggregate pearlite. The use of an ultra-light aggregate as proposed herein makes it possible to easily reduce the weight of concrete. For example, it is possible to reduce the air-dry specific gravity of concrete to about 0.94, but the compressive strength is 12 to Only about 18 MPa is obtained, and high strength is hardly obtained. In addition, since the ultra-lightweight coarse aggregate has a high water absorption rate, there is a possibility that the moisture content varies during management and the compressive strength of the product varies.

[0007] Further, as described above, while using an ultra-light aggregate to reduce the weight, while reducing the water-cement ratio, increasing the air-dry specific gravity to a certain extent, and increasing the strength, the balance between weight reduction and high strength is achieved. Although a method of achieving this has been proposed, there is a limit in improving the compressive strength of a composition using a conventional general-purpose ultralight aggregate. For example, in the composition using the above-mentioned pearlite, even if the water-cement ratio is reduced and the air-dry specific gravity is increased to about 1.4, the compressive strength is only about 25 to 29 MPa, which is 30 MPa which can be used for high-rise buildings. It is difficult to obtain the above compressive strength. Further, a method of adding ultra-fine silica powder in addition to ultra-light aggregate has been proposed, but it is not enough to reduce weight and increase strength, and it is economical to use expensive ultra-fine silica powder. Is also disadvantageous.

[0008] In the case of using ultra-light fine aggregate, there is also a problem that the aggregate is easily lifted before the paste solidifies because the aggregate is too light. To solve such a problem, Japanese Patent Application Laid-Open No. 8-157278 discloses a particle size of 5.
A concrete composition using an ultra-lightweight fine aggregate obtained by firing fine powder of mica rhyolite as a sub-mm aggregate and a ceramic lightweight foam of a completely closed hollow sphere has been proposed. The publication states that the use of ultra-lightweight fine aggregates requires 1.2
By adding a fine powder lightweight foam having a particle size of about 0.4 mm or less to the part where the particle size is less than mm, the particle size distribution is continued at 5 mm or less, and the addition of the fine powder suppresses the separation of aggregate. I have. In addition, by using only ultra-light aggregates to reduce the weight, on the other hand, by entrapping air bubbles and not reducing the strength of the paste part only by air, specific gravity 0.8 to
1.2 makes it possible to obtain a concrete product having a compressive strength of 30 MPa level.

However, in the above method, further improvement in the effect of suppressing the separation of aggregate is desired. Furthermore, since an ultralight coarse aggregate having a high water absorption is used, the compressive strength of the product may vary. In addition, in this method, all aggregates use ultra-light products, including coarse aggregates, and foams use limited products, and the composition is limited to compounding conditions using special products. It is difficult to use general-purpose commercial products.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and is lightweight, has high compressive strength, has a small variation in specific gravity and strength distribution, and has a smooth and finished surface. Aims to provide a clean cement culture.

[0010]

Means for Solving the Problems The present inventor has proposed that, among ultra-lightweight fine aggregates as fine aggregates, the particle size is less than 1.2 mm,
In addition, it is found that if only those having an absolute dry specific gravity of 0.5 or more and less than 1 are used in a limited manner, it is possible to obtain a lightweight and high-strength concrete even if a relatively large amount of gas is contained in the paste portion. Was. By including this ultra-light aggregate and a foam having a specific particle size in a specific amount, and including a gas in a specific amount, it has been found that the above-mentioned requirements can be solved at once using a general-purpose material. Thus, the present invention has been completed.

[0011] More specifically, when the ultra-fine aggregate having a particle size of less than 1.2 mm and a foam having a particle size of 0.6 mm or less are used in combination, the aggregate has a continuous particle size of less than 1.2 mm. If the specific gravity of the paste part is reduced by including the gas in a specific amount, and the specific gravity difference with the aggregate is reduced, it has light weight and high compressive strength, and the distribution of specific gravity and strength varies. Mortar and concrete having a beautiful surface can be obtained, and the present invention has been completed.

That is, the cement culture according to the present invention comprises:
Cement, an ultralight fine aggregate having a particle size of less than 1.2 mm and an absolute dry specific gravity of 0.5 or more and less than 1;
A water admixture of a cement composition comprising a foam of 6 mm or less and containing the foam in an amount of 5 to 40% by volume based on the total volume of the ultralight fine aggregate and the foam is obtained by curing and solidifying. , And gas in an amount of 6 to 10% by volume. This gas amount is more preferably 6 to 8% by volume. Further, it is desirable that the above-mentioned gas amount includes a gas due to a foaming agent. A cement culture containing coarse aggregate in addition to the above components is preferred. In the present invention, concrete having an air-dried specific gravity of 1.3 or less and a compressive strength of 30 MPa or more can be obtained as the cement-cultured organism as described above.

In the above, the absolute dry gravity of the foam is usually from 0.8 to 1.5. The water-cement ratio in the present invention is preferably 40 to 55% by weight. According to the present invention, it is possible to obtain a mortar or concrete which is lightweight, has high compressive strength, has little variation in specific gravity and strength distribution, and is excellent in surface appearance.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.
The mortar is obtained by curing and solidifying a water admixture of a cement composition containing cement and fine aggregate, and the concrete is such that the mortar further contains coarse aggregate. 10m among aggregates mixed with mortar or concrete
85% by mass of 5mm screen sieve through all m screen sieves
The aggregate passing through is fine aggregate, and it is 85 mass by 5 mm net sieve.
Aggregate that remains in more than% is coarse aggregate.

In the present invention, as the cement composition for mortar and concrete as described above, cement and an ultralight fine aggregate having a particle size of less than 1.2 mm and a bone-dry specific gravity of 0.5 or more and less than 1 are used. And a foam having a particle size of 0.6 mm or less are used. Here, the term “consisting of cement, the ultralight fine aggregate and the foam specified above” does not substantially include other fine aggregates and foams other than the above, and is essentially related to specific gravity and particle size. It means that other additives, impurities and the like may be included. First, each component contained in the cement composition of the present invention will be described.

In the present invention, general-purpose cement can be used without any particular limitation. For example, ordinary portland cement, blast furnace cement, fly ash cement,
Early-strength Portland cement, particle size adjusting cement and the like can be used. These may be used in combination.

In the present invention, as the fine aggregate, among ultra-lightweight fine aggregates, those having a particle size of less than 1.2 mm and a specific gravity of 0.5 to less than 1 are used. In this specification, the aggregate having a particle diameter of less than 1.2 mm is an aggregate having a particle diameter passing through a 1.2 mm sieve, and includes all particles having a particle diameter of less than 1.2 mm. Particle size 1.2mm
These particles are not substantially contained.

When the absolute specific gravity of the aggregate is 0.5 or more and less than 1, all the individual particles (aggregates) have the absolute dry specific gravity of 0.5 or more and 1 or less.
The ultra-fine aggregate having a particle size of less than 1.2 mm and a specific gravity of 0.5 to less than 1 is defined as “1.
Among the aggregate particles passing through the 2 mm sieve, those having an absolute dry specific gravity of 0.5 or more and less than 1 are in other words, even if the particle diameter is less than 1.2 mm, the absolute dry specific gravity is not more than 0.1. Particles less than 5 or more than 1 are not included.

Therefore, among all the particles having a particle size of less than 1.2 mm, the minimum value of the particle size is substantially limited so as to satisfy the above absolute dry specific gravity. Further, the ultra-lightweight fine aggregate used in the present invention is usually produced by firing glass or coal ash or the like.
Substantially no mm or less exist. The absolute dry specific gravity refers to a value obtained by dividing the mass of the aggregate in the absolute dry state by the mass of water having the same volume as the absolute volume of the aggregate.
4, 1135.

In the present invention, the particle size is 1.2 mm.
The ultra-fine aggregate having a specific gravity of less than 1 and having a specific gravity of less than 1 does not include those having a specific gravity of less than 0.5. It is possible to obtain mortar or concrete with extremely high compressive strength. It is considered that the ultralight fine aggregate used in the present invention has the following specific structure.

The ultralight fine aggregate (particles) is lightened by including air bubbles in the particles, and the absolute dry specific gravity of the ultralight fine aggregate of less than 1 is based on the cell volume ratio. Means greater. As such ultralight fine aggregates, particles having a balloon structure or particles having a porous structure are conventionally known, and those having a balloon structure have a particle diameter of less than 1.2 mm because most of the volume is hollow. The absolute density is extremely light, about 0.25, and the particle size is 1.2m.
Those having a porous structure of less than m have an absolute dry specific gravity of about 0.4.

On the other hand, the ultra-fine aggregate used in the present invention has a particle diameter of less than 1.2 mm and an absolute dry specific gravity of 0.
The particles having a number of 5 or more and less than 1 have a coarse-dense two-layer structure having a porous outer layer having a plurality of voids (pores) in the inside of the particles and having substantially no voids on the outer periphery thereof. And it is presumed that the strength of the aggregate is substantially governed by the strong outer shell layer. By having such a coarse-dense two-layer structure,
The strength can be effectively developed while being lightweight. Further, according to the study of the present inventor, the thickness of the outer shell layer is substantially constant regardless of the size of the particle size. For this reason, those having a particle size of less than 1.2 mm and a specific gravity of 0.5 to less than 1 can express the lightening effect of the porous material and the high strength effect of the outer shell layer in a particularly well-balanced manner.
For example, even if the particle size is less than 1.2 mm, if the particle size is too small, it is not possible to maintain such a coarse-dense two-layer structure,
For example, those with no pores inside the particles have a bone-dry specific gravity of 1
That is all.

The inventor of the present invention has reported that the inside of the ultralight fine aggregate particles having a particle size of 1.2 mm or more is porous having a plurality of voids (holes) and the outer periphery thereof is a solid outer shell having substantially no voids. The use of a dense and dense dual structure with layers was also studied, but even if the water-cement ratio is reduced, concrete compressive strength does not improve much, so aggregate strength controls concrete compressive strength. I thought it might be. Based on this, the relationship between the strength of the paste part and the concrete compressive strength was investigated. The results are shown in FIG. In other words, the addition of an ultra-light fine aggregate having a large particle size destroys the aggregate, and does not significantly improve the concrete compressive strength. If the strength of the paste part is forcibly increased, the concrete strength will be 30MP
However, the weight increases and the weight is not reduced. Therefore, by reducing the source of fracture of concrete (ultra-fine aggregate having a large particle size), that is, ultra-fine aggregate having a bone-dry specific gravity of 0.5 or more and less than 1 and a particle size of less than 1.2 mm It has been found that the use of No. can maintain the concrete strength even if the strength of the paste portion is not so high.

In the present invention, by using the above-mentioned specific ultra-lightweight fine aggregate, the contradictory effects of using the lightweight aggregate in the prior art, in which the strength is reduced, can be both achieved. In addition, even among the ultra-light aggregates having a particle diameter of less than 1.2 mm and an absolute dry specific gravity of 0.5 or more and less than 1, if the absolute dry specific gravity is too small, there is a tendency to separate from the cement paste portion, If the particle size is too small, the fluidity and moldability tend to decrease, so the particle size is 0.6 mm or more and 1.2 or less.
Those having a diameter of less than 0.7 mm and an absolute dry gravity of 0.7 to 0.9 are preferred because they can effectively exhibit light weight and high compressive strength.

In the structure of the present invention, it is possible to obtain concrete having an air-drying specific gravity of 1.3 or less and a compressive strength of 30 MPa or more by using the above-mentioned ultra-lightweight fine aggregate. Concrete having the same air-dried specific gravity as above using a material having a particle diameter of 1.2 mm or more even if it is less than 1 or a material having an absolute dry gravity of less than 0.5 even if the particle size is less than 1.2 mm. When manufactured, it is difficult to obtain a compressive strength of 30 MPa or more.

The above-mentioned ultralight fine aggregate is a natural aggregate,
Any of artificial aggregates may be used. The artificial ultralight fine aggregate can be produced by, for example, pulverizing an inorganic substance such as glass, coal ash, and anti-firestone, mixing with a clay or a foaming agent, granulating the mixture, and then firing. At this time, an ultralight fine aggregate is manufactured under the condition that the above-mentioned coarse-dense two-layer structure is obtained, and then sieved to obtain a particle diameter of less than 1.2 mm and an absolute dry specific gravity of 0.5.
未 満 1 can be collected. Commercial products such as glass light GL1 (trade name G light, manufactured by Sunlight Co., Ltd.) and NL (trade name N light, manufactured by Naigai Ceramic Co., Ltd.) can be used as the ultralight fine aggregate as described above.

In the present invention, a foam having a particle size of 0.6 mm or less is used together with the above ultralight fine aggregate. The foam is desirably a lightweight foam having a specific gravity close to that of an ultralight fine aggregate. Specifically, the absolute dry specific gravity is usually 0.8-1.
It is about 5 and preferably 1.0 to 1.3. It is desirable that the particle size be 0.6 mm or less and have a gentle short-degree distribution.

Such foams include pearlite,
Shirasu balloons, glass balloons (glass beads), fly ash balloons, ceramic completely closed lightweight foams and the like can be used, and these can be used in combination. The details of the composition and the manufacturing method of this completely closed lightweight foam are disclosed in JP-A-8-157278, and the manufacturing method and the like can be used in the present invention.

This foam has a so-called balloon structure with respect to the structure of the above-mentioned ultralight fine aggregate, but does not necessarily have to be a completely closed type. For example, the absolute dry specific gravity of the above-mentioned ceramic type completely closed lightweight foam is 0.6 to 0.9, the particle size is about 0.35 mm or less,
When this is used, the bearing effect is large and fluidity can be obtained. On the other hand, the fluidity becomes so high that the effect of suppressing the separation due to the addition of the foam may not be easily exerted.

In the present invention, by using the above-mentioned ultralight fine aggregate together with a foam having a particle size of 0.6 mm or less, the foam exhibits an effect of suppressing the floating of the ultralight fine aggregate. For this reason, at the time of ironing, there is obtained an effect that a product excellent in surface aesthetics can be obtained without the surface becoming dirty due to the presence of small unevenness due to the ultra-lightweight fine aggregate on the surface. In addition, the foam is mixed into the paste to reduce the difference in specific gravity between the paste and the ultra-lightweight fine aggregate, thereby exhibiting an effect of suppressing separation. In addition, the particle size distribution is continuous below 1.2 mm, and the specific gravity of the ultra-light aggregate and the foam are close to each other. Distributed. Therefore, an effect that a product having no unevenness in specific gravity and no unevenness in strength can be obtained is exhibited.

FIG. 2 shows the effect of suppressing the separation of aggregates by such a foam by the difference in specific gravity of air-drying in the height direction of concrete. 10 cm diameter x 20 height with foam
cm concrete was divided into four parts in the height direction, and the air-drying specific gravity at each height was examined. It can be seen that the difference in air-dry specific gravity with respect to height is smaller when the foam is introduced. Therefore, the variation in the compressive strength of the concrete is reduced.

The volume ratio of the foam as described above is 5 to 5 in the total volume of the fine aggregate, that is, the foam and the ultralight aggregate.
It is used in an amount of 40% by volume, preferably 10 to 35% by volume. When the volume ratio of the foam is 5% by volume or more, an effect of suppressing aggregate separation is exhibited. On the other hand, if it exceeds 40% by volume, the viscosity of the concrete increases, and the effect of the breakage of the foam during kneading increases, and the product tends to be unstable.

A mortar can be obtained from the cement composition comprising the ultralight fine aggregate, foam and cement as described above. Concrete further contains coarse aggregate. The coarse aggregate is not particularly limited, but is preferably a coarse aggregate having a relatively uniform internal structure. The absolute dry specific gravity of the coarse aggregate is preferably 0.9 or more, more preferably 0.9 or more.
１1.3. Although the particle size of the coarse aggregate is not particularly limited as long as it is 5 mm or more, it is usually 5 to 25 mm, preferably 5 to 25 mm.
To 20 mm, more preferably 5 to 15 mm. Examples of such coarse aggregate include Super Mesalite (trade name of ultra-light coarse coarse aggregate having a specific gravity of less than 1; manufactured by Nippon Mesalite Co., Ltd.) and Mesalite (trade name of lightweight coarse aggregate having a specific gravity of approximately 1.25) , Manufactured by Nippon Mesalite Co., Ltd.), asanolite (trade name of a lightweight coarse aggregate having an absolute dry specific gravity of about 1.25), and the like. Further, an ultralight coarse aggregate having a specific gravity of less than 1 and a lightweight coarse aggregate having a specific gravity of 1 or more may be used in combination.

In the present invention, the ultra-lightweight fine aggregate as described above,
A foam and a cement composition for mortar containing cement or a cement composition for concrete in which coarse aggregate is further added thereto are kneaded with water to prepare a water admixture, which is cured and solidified to cure the cement. That is, mortar or concrete is obtained.

In preparing the above cement composition, the ultralight fine aggregate is usually 0.2 to 1.2 liter, preferably 1 to 1 liter of the cement (water) + paste (binding material). Is compounded in an amount of 0.5 to 0.9 liter. Although the volume ratio of the foam to the ultralight fine aggregate is described above, the foam is usually 0.02 to 1 liter of paste.
0.55 liter, preferably 0.05 to 0.30 liter. Coarse aggregate is 1m of concrete
It is used in an amount of usually 250 to 450 liters, preferably 300 to 400 liters with respect to ³ .

In the present invention, a gas such as air is positively contained, and 6-1 to 1 in the final cement culture.
It is included in an amount of 0% by volume. When the gas is contained in such an amount, the weight can be effectively reduced, and since the paste portion contains the gas, the specific gravity difference between the paste portion and the aggregate portion is reduced, so that the separation of the aggregate can be suppressed.

When a gas is contained in the paste portion, the concrete strength decreases. In the present invention, a high-strength concrete can be obtained even if the gas is contained in the above amount. This is because the strength of the ultralight fine aggregate used in the present invention,
This is because the target strength can be obtained even when the paste strength is reduced because the concrete strength is controlled. According to such a method, even when a general-purpose ultra-lightweight fine aggregate is used, both weight reduction and high strength can be achieved. However, if a gas is excessively introduced into the paste, a continuous layer of the gas is formed, and the paste strength starts to decrease rapidly. Investigations have revealed that in the composition of the present invention, when the gas amount is 10% by volume or less, the paste strength does not adversely affect the concrete strength. This gas amount is preferably 6 to 8% by volume. The gas amount here does not include the gas in the aggregate and the foam.

The amount of gas (total porosity) in the cured product is
It can be measured according to JIS A1116 as described later. The amount of gas in the product is almost the same as the amount of gas in fresh mortar or fresh concrete before curing. In order to introduce the above amount of gas, it is desirable to generate a gas by using a foaming agent in addition to the entrapped air at the time of kneading the paste. For example, there is a mixed foam method in which a foaming agent is added together with water to a cement composition to generate air bubbles during kneading, or a preform method in which previously formed air bubbles are mixed into a paste or a water admixture of a cement composition. Both methods are known and can be employed. Among these, the mixed foam method is preferable because the strength is less reduced when a large amount of gas is introduced. As the foaming agent, for example, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, or the like can be used.

The water-cement ratio is determined from the absolute dry weight and the amount of aggregate in consideration of the specific gravity and strength of the obtained product in addition to the fluidity of the water mixture. In the present invention using the above cement composition, the water-cement ratio can be increased to increase the amount of entrained air. The water cement ratio is usually about 40 to 50% by weight. Here, the water-cement ratio is defined as the concrete 1 before curing (when mixed).
The ratio of the weight of water and cement per m ³ is represented by {(weight of water) / weight of cement} × 100.

In the cement composition as described above, fine aggregates other than ultralight fine aggregates, coarse aggregates, admixtures, admixtures may be appropriately added as needed as long as the object of the present invention is not impaired. Agents and the like can be added. As the admixture arbitrarily added, an admixture generally added to cement can be widely mentioned, for example, an inorganic fine powder (inorganic admixture), a foaming agent, a water reducing agent, a thickener, a fluidizing agent. Agent (high-performance water reducing agent), AE agent, fiber, pigment, setting retarder, curing accelerator,
Examples thereof include a coagulant, a waterproofing agent, a water repellent, an elasticity-imparting agent, and a rust inhibitor. These admixtures are used in an appropriate amount according to the purpose of use.

Examples of the inorganic admixture include silica fume, fly ash, blast furnace slag fine powder, silica stone fine powder, diatomaceous earth fine powder, and limestone fine powder, and these may be used in combination. Specifically, the inorganic admixture is 4000
It is preferably a fine powder having a size of about 20,000 branes. Such an inorganic admixture can be used in an amount of 20 parts by weight or less based on 100 parts by weight of cement. The inorganic admixture is usually included in a paste (binder).
Examples of the water reducing agent include naphthalene-based, melamine-based,
A water reducing agent such as a polycarboxylic acid can be used.

As the fine aggregate other than the ultralight fine aggregate, a fine aggregate having an absolute dry specific gravity of 1 or more, specifically, a general-purpose lightweight fine aggregate and / or a normal fine aggregate can be used. The particle size of the lightweight fine aggregate is not particularly limited as long as it is less than 5 mm, but is preferably 0.3 to less than 5 mm. The absolute specific gravity is preferably 1 to 1.9, more preferably 1.6 to 1.9.
1.8. Light fine aggregate usually has a relatively homogeneous internal structure. Commercial products such as mesalite (a lightweight fine aggregate having an absolutely dry specific gravity of about 1.7, manufactured by Nippon Mesalite Co., Ltd.) can also be used as such a lightweight fine aggregate. Examples of ordinary fine aggregate include sea sand and river sand having a specific gravity of about 2.6.

As another fine aggregate, a lightweight fine aggregate and a general fine aggregate can be used in combination. Other fine aggregates vary depending on their absolute dry specific gravity, particle size, etc., but are usually 0 to 0.4 per liter of cement + water + gas paste.
Liter, preferably from 0 to 0.3 liter, and less than 50% by weight, preferably less than 50% by weight, based on the total amount (100% by weight) of the ultralight fine aggregate and other fine aggregates. Can be used in an amount of less than 40% by weight. The use of other fine aggregates as described above does not reduce the compressive strength of the mortar or concrete, but the other fine aggregates are used in an amount that does not ultimately hinder the weight reduction of the mortar or concrete. .

From the cement composition as described above, a lightweight and high-strength cement culture can be obtained.
The curing method is not particularly limited, and any method such as underwater curing, aerial curing, combined curing, and steam curing can be employed. Heating or cooling may be performed during curing, or the surroundings may be covered with cloth, wood, or the like. In the present invention, a concrete having a compressive strength of 30 MPa or more can be obtained even if the air-dry specific gravity is 1.3 or less, but more specifically, a compressive strength of 35 MPa or more at an air-dry specific gravity of about 1.3, In addition, concrete having an air-drying specific gravity of about 1.1 and a compressive strength of 30 MPa or more can be obtained. The air-dry specific gravity refers to the specific gravity of a living organism (mortar or concrete) after air drying. Such lightweight and high compressive strength mortar or concrete is useful, for example, as a precast material such as a curtain wall constituting an outer wall of a building.

[0045]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.
The measurement conditions for the particle size of the aggregate, the absolute dry gravity, the amount of air in the concrete (total porosity), the air dry specific gravity, and the compressive strength are as follows. The particle size of the aggregate was measured according to JIS A1102. The absolute dry specific gravity was measured according to JIS A1134, 1135. The compressive strength was measured according to JIS A1108. The total porosity was measured according to JIS A1116. The air-dry specific gravity was determined by leaving the unframed cultured organism at a constant weight at a temperature of 20 ° C. and a relative humidity of 50%, and dividing the weight by the volume. Concrete kneaded material (fresh)
The flowability, separation property, and ironing property of the sample were evaluated as follows. Flowability: A kneaded material of 0.25 m ³ is funnel (inner diameter φ1 of leg)
(50 mm). …: Passed for less than 5 seconds ×: required for more than 5 seconds Separability: Whether the kneaded material was separated immediately after kneading was visually observed. Iron finish: When the kneaded material is applied using an iron, the surface is smooth and clean. The surface has small irregularities or fine aggregates and has a rough surface.

The components in the tables used in the examples and comparative examples are shown below. <Cement>-Ordinary Portland cement (abbreviated as A in the table) (specific gravity 3.16)-Blast furnace cement B (abbreviated as B in the table) (specific gravity 3.04) <Fine inorganic powder (inorganic admixture)>-Silica fume (20,000 branes) (abbreviated as C in the table) (specific gravity 2.2)-Ultra-fine blast furnace slag powder (8000 branes) (abbreviated as D in the table) (specific gravity 2.9) <Aggregate>-Ultralight fine aggregate a: Particle size less than 1.2 mm, absolute dry specific gravity 0.
8 (trade name G light, manufactured by Sunlight Co., Ltd.) ・ Ultralight fine aggregate b: particle size 1.2 to 2.5 mm, specific gravity 0.65 (brand name G light, manufactured by Sunlight Co., Ltd.) ・ Lightweight coarse Aggregate: Particle size 5 to 25 mm, specific gravity 1.2
5 (trade name: Mesalight, manufactured by Nippon Mesalight Co., Ltd.) <Foam> Foam: particle diameter less than 0.6 mm, absolute dry specific gravity 1.15
(Product name Fuyolite No. 0, manufactured by Fuyo Perlite)

(Examples 1 to 12) Cement, water, ultra-light fine aggregate, lightweight coarse aggregate and foam were blended in the amounts shown in Table 1.
During kneading, a foaming agent (anionic surfactant, SR-1 manufactured by Sanyo Kasei Kogyo Co., Ltd.) was introduced so as to have a predetermined air amount, and a melamine-based water reducing agent was added in an amount of 10 m to 20 m of the slump. The kneaded material was poured into a mold and cured in the air for 28 days to obtain concrete. Table 1 shows the flowability, separability, ironing property, air volume (air volume), air-dry specific gravity, and compressive strength of concrete (28 days old) of the kneaded material.

(Comparative Examples 1 to 6) Except that the components shown in Table 1 were used and the amounts of the foaming agent and the water reducing agent were adjusted to adjust the air amount to the ratio shown in Table 1, the same procedure as in Example 1 was carried out. , Kneaded material,
Next, concrete was obtained. Table 1 shows the results.

[0049]

[Table 1]

[0050]

According to the present invention, there is provided a cement-cultured organism which is lightweight, has high strength, has a small variation in specific gravity and strength distribution, and has excellent surface appearance at the time of ironing. Even lightweight concrete having an air-dry specific gravity of 1.3 or less has a compressive strength of 30 MPa or more. Such concrete is useful as a precast material for high-rise buildings requiring light weight and high strength.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between paste strength and concrete compressive strength.

FIG. 2 is a diagram showing a density distribution in the thickness direction of concrete.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor ▲ Takato Ki Masato 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Kawasaki Steel Research Institute (72) Inventor Masato Kumagai Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture 1 No. 1 Kawasaki Steel Engineering Co., Ltd. (72) Inventor Kenji Kawamoto 3-6-24 Uozaki Minami-cho, Higashi-Nada-ku, Kobe City, Hyogo Prefecture F-term (reference) 4G012 PA02 PE05 4G019 LA02 LB01 LB02 LD02

Claims (3)

[Claims] 1. A cement comprising: ultra-fine aggregate having a particle diameter of less than 1.2 mm and a specific gravity of 0.5 to less than 1; and a foam having a particle diameter of 0.6 mm or less. The foam is 5 to 40% of the total volume of the ultralight fine aggregate and the foam.
A cement cured product obtained by curing and solidifying a water admixture of a cement composition containing the gas in an amount of 6% to 10% by volume. 2. The cement-cultured organism according to claim 1, further comprising coarse aggregate. 3. The cement-cultured organism according to claim 2, having an air-drying specific gravity of 1.3 or less and a compressive strength of 30 MPa or more.