JP2003104765A - Porous concrete molding for planting and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous concrete molding for planting with an alkali ingredient adverse to growing of plants neutralized, having very high coefficient of permeability, and compression strength usable for regular structural member and pavement member. SOLUTION: The porous concrete molding for planting is a hardened body of a hydraulic composition composed of cement, rough aggregate, water, and a dispersant, wherein, an alkali ingredient is neutralized by carbonization with carbon dioxide, porosity is >=26%, coefficient of permiability is >=2.0 cm/s, compression strength is >=30 N/mm<2> . The method for manufacturing the same is that the hydraulic composition containing cement, aggregate, water, and a dispersant is kneaded in a mixer, subjected to press and vibration forming, thereafter, cured with carbon dioxide gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous concrete molded product for planting and a method for producing the same, and in particular, it has a large porosity and is required to have an extremely high water permeability and an ordinary concrete structural member or pavement member. The present invention relates to a porous concrete molding for planting having a strength equal to or higher than that of concrete, and a method for producing the same.

[0002]

2. Description of the Related Art Porous concrete compacts have a high void ratio, but on the other hand, they have the disadvantage of low compressive strength.
Therefore, conventionally, it has not been widely used as a structural member. On the other hand, as secondary concrete products, rainwater-penetrating, water-permeable gutters, water-permeable concrete for pavement, etc. have been developed as products, and recently, water-permeable concrete has been widely used.

As a new use, such a permeable concrete is filled with soil containing plant seeds and nutrients in voids, and a method of growing plants on the concrete surface has been actively used in recent years. ing. Porous concrete has come to be applied to the construction method, and a construction method using concrete called greening concrete or planting concrete has been developed. Greened concrete and planted concrete are often used in places such as the side wall of rivers and slopes of embankments, etc., which contribute to the improvement of the natural landscape, but generally require structural strength. It is rarely used in some cases.

The porous concrete used for the above-mentioned applications is generally a powder of cement or the like and the powder 10
It is produced by kneading about 35% by weight of water, 0 parts by weight, coarse aggregate, dispersant, and fine aggregate, and uniformly adhering the cement paste to the aggregate.

The concrete thus produced is
It is generally formed by directly scattering to a predetermined place partitioned by a mold having a predetermined shape or a mold and subjecting the surface to vibration using an external vibrator or the like. In particular, for the purpose of in-situ construction, most of them are based on the above construction method.

However, in the above method, the grain size of the coarse aggregate is 1
When it is about 0 to 20 mm, the porous concrete molded body has a water permeability coefficient of 2.0 cm / sec and a compressive strength of 5 N / mm.
^The limit was to have a performance of about ² . Further, when the particle diameter of the coarse aggregate is about 5 to 10 mm, it was limited to the performance of the water permeability of 2.0 cm / sec and the compressive strength of about 10 N / mm ² .

On the other hand, there is a porous concrete molded body obtained by vibrating and compacting, but when the porous concrete molded body is vibrated, the aggregate and the paste are separated due to excessive fluidity, and the paste portion Will flow down to the bottom of the mold and block the voids, resulting in a significant decrease in hydraulic conductivity, and the paste amount will be insufficient at the top of the molded product, resulting in a non-uniform cured product as a whole, resulting in reduced strength. Will happen. In order to improve this, a porous concrete molded body obtained by adding a surfactant to reduce the unit water content and further adding fine aggregate having a particle size of less than 5 mm to the aggregate has been developed.

However, even when such a porous concrete compact is used, a result that the compressive strength exceeds 30 N / mm ² can be obtained in a region having a high water permeability of 2.0 cm / sec or more. However, in order to obtain a porous concrete molded body having a compressive strength of 30 N / mm ² or more, the current situation is that it cannot be obtained unless the water permeability coefficient is reduced to 1.2 cm / sec or less.

Further, the cement hydration composition exhibits strong alkalinity, which may adversely affect the growth of plants. Therefore, neutralization treatment is necessary, and the following several methods have been adopted. For example, the first manufactured with a weak acid liquid generator
A method of spraying a 15% by weight weakly acidic solution of ammonium phosphate on porous concrete with a liquid spraying device, and
For example, a method of adding dry ice to neutralize with carbon dioxide gas generated by sublimation.

However, the neutralization of the current situation by the above-mentioned method, etc.
With technology, compressive strength is 30 N / mm ^TwoAbove, and water permeability
Pola with high permeability that coefficient is more than 2.0cm / sec.
It is very difficult to manufacture concrete molded products
It In particular, the latter method uses carbon dioxide with dry ice.
Due to the curing, the temperature becomes very low, carbonation is slow,
It is difficult to reach a certain strength. On the other hand, with the structure
The minimum required compressive strength is 18 N / mm^Twoage
If this occurs, the compressive strength will always be satisfied, and
Considering the range of sticking, compression of porous concrete
Strength is 24 N / mm^TwoDegree required and also pavement structure
The compressive strength required for the product is 30 N / mm^Two
Is required.

Further, as a method of increasing the strength of the hardened cement product by carbonation, Ca (OH) ₂ precipitated by hydration of the cement is contacted with carbon dioxide gas to change into CaCO ₃ and the hardened cement product is obtained. There is known a method of filling the pores of the above and increasing the strength of the cured body. Ca (OH) ₂ + CO ₂ → CaCO ₃ + H
₂ O However, it is difficult to carbonate the inside of the hardened cement by this method, and it takes a long time to cure in a carbon dioxide atmosphere, and the effect of carbonation such as poor productivity cannot be fully exerted. There was a difficulty.

[0012]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to have an extremely high water permeability and a compressive strength applicable to ordinary structural members and paving members. A porous concrete compact and a method for producing the same.

Further, in addition to the above objects, another object of the present invention is to form porous concrete for planting in which alkaline components which adversely affect the growth of plants are neutralized by forced carbonation. A body and a method for manufacturing the body.

[0014]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, the raw material has a specific composition and is highly carbonized by carbon dioxide discharged from, for example, a cement firing kiln or a boiler for curing. It was found that a porous concrete molding for planting having water permeability, high strength, and neutralized alkaline components can be produced.

The porous concrete molded product for planting of the present invention is a hardened product of a hydraulic composition containing cement, coarse aggregate, water and a dispersant, and is alkalized by carbonation with carbon dioxide gas. The components are neutralized, the porosity is 26% or more, the water permeability is 2.0 cm / sec or more, and the compressive strength is 30 N / mm ² or more.

[0016] A preferable porous concrete molded body for planting of the present invention is characterized in that the above-mentioned porous concrete molded body for planting further contains an inorganic powder.

Further, the preferable porous concrete molded body for planting of the present invention is the porous porous concrete molded body for planting, wherein 1 to 5 parts by weight of the dispersant is added to 100 parts by weight of cement and the inorganic powder in total. And 20 parts by weight of water, and further mixed such that the mixed volume thereof is 35 to 45% by volume with respect to the volume of the coarse aggregate.

The method for producing a porous concrete molded product for planting of the present invention is a hydraulic composition containing cement, coarse aggregate, water and a dispersant in producing the porous concrete molded product for planting of the present invention. The method is characterized by including a step of charging the material into a mixer, kneading, then charging in a mold, pressure vibration molding, and then curing with carbon dioxide.

Further, preferably, in the method for producing a porous concrete molded body for planting, the carbon dioxide curing is
It is characterized in that it is carried out in an atmosphere containing a temperature of 30 to 80 ° C. and a carbon dioxide gas of 5 to 20%.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Porous concrete for planting of the present invention
The molded products are cement, coarse aggregate, water and dispersant, and
If necessary, the hardness of the hydraulic composition containing inorganic powder
By being carbonated by carbon dioxide
Alkaline component is neutralized and porosity is 26% or more.
Above, water permeability is 2.0 cm / sec or more, compressive strength is 30N
/ Mm ^TwoIt has the above characteristics.

The cement used in the present invention is not particularly limited, but for example, ordinary Portland cement,
It is possible to use hydraulic Portland cement such as early-strength Portland cement, and also eco-cement, which has been recently talked about and manufactured using municipal waste.

As the coarse aggregate used in the present invention, a commonly used hard aggregate having a particle size of 5.0 mm or more can be used. Here, the hard aggregate is not particularly limited as long as the compression strength of the rough is at least about 60 N / mm ² , and it is durable and is usually used as an aggregate for concrete. Natural aggregates such as gravel, semi-artificial aggregates such as crushed stone, and artificial aggregates such as lightweight aggregates can be used.

Further, as the dispersant, a commonly used dispersant such as an AE water reducing agent, a high performance water reducing agent and a high performance AE water reducing agent can be used. Such a dispersant has a function of sufficiently kneading the paste with a small amount of water and, at the same time, imparting a thixotropic property required for exhibiting fluidity to the paste by vibrating at a high frequency. Particularly, in the present invention, those belonging to the high-performance water reducing agent and the high-performance AE water reducing agent are preferable, and the polycarboxylic acid-based high-performance AE is preferable.
The use of a water reducing agent is particularly preferable because it works effectively even if the amount used is small.

Further, the inorganic powder that is optionally contained includes, for example, coal ash, blast furnace slag fine powder, silica fume, limestone powder, silica stone powder, iron powder and the like. By containing these inorganic powders, the strength development of the concrete molded body and the fluidity at the time of compaction by pressure vibration can be further improved.

The hardened body of the hydraulic composition contains the above-mentioned cement, coarse aggregate, dispersant, and water, and if necessary, inorganic powder. The mixing ratio is 100 parts by weight of cement, and if inorganic powder is added as necessary, the dispersant is 1 to 5 parts by weight with respect to 100 parts by weight of cement and the inorganic powder. It is preferable. If it is less than 1 part by weight, the dispersion effect cannot be sufficiently exerted,
If it exceeds 5 parts by weight, suitable fluidity and viscosity cannot be obtained.

The amount of water added is 100 parts by weight of cement, and if inorganic powder is added as required, 7 to 2 is added to 100 parts by weight of the total amount of cement and the inorganic powder.
0 parts by weight is preferred. If it is less than 7 parts by weight, the paste of cement, dispersant, water, and inorganic powder added as necessary (hereinafter referred to as cement paste) cannot be sufficiently dispersed, and it becomes uniform when coarse aggregate is mixed. Cannot granulate. On the other hand, if it exceeds 20 parts by weight, the paste portion will flow down to the lower part of the mold and it will be difficult to maintain a uniform state of the molded body, and the water permeability will decrease.

The blending ratio of the coarse aggregate is such that the mixing volume ratio of the cement paste is the actual ratio of the coarse aggregate (the net volume ratio of the aggregate in a unit volume, which is usually in the range of 50 to 70% by volume). It is difficult to determine uniformly because it depends on the above, but in order to show a high water permeability of 2.0 cm / sec or more, the permeability coefficient of the obtained porous concrete molded body is
It is preferable that the mixing volume of the cement paste portion is 35 to 45% by volume with respect to the volume of the coarse aggregate. If it is less than 35% by volume, it is relatively easy to obtain a high water permeability having a water permeability coefficient of 2.0 cm / sec or more, but the compressive strength is 3
It may be less than 0 N / mm ² , and sufficient strength may not be obtained. On the other hand, when it exceeds 45% by volume, the cement paste portion increases and the continuous void portion is filled with the cement paste, which makes it difficult to obtain high water permeability.

The porous concrete molding for planting of the present invention is prepared by adding a cement, coarse aggregate, water and a dispersant and, if necessary, a hydraulic composition containing an inorganic powder to a mixer and kneading the mixture. Then, after being placed in a mold, it is manufactured by a method including a step of pressure vibration molding and then curing with carbon dioxide gas.

As a mixer used for kneading when preparing a hydraulic composition, an omni mixer is preferably used because the kneading water amount may be the smallest. Twin screw mixer,
The compulsory mixer and the mixer used for kneading differ depending on the amount of kneading water and the influence of the dispersant, but are not particularly limited as long as they are of the type used for ordinary kneading of concrete, and any type may be used.

Further, the kneading method is not particularly limited, but when the kneading order is such that the cement paste is first kneaded and then the coarse aggregate is added, the cement paste uniformly covers the surface of the coarse aggregate. This is preferable because it takes less time. When such a split kneading method is used, a uniform coating state of the cement paste can be obtained by adding the coarse aggregate and kneading for 1 minute or more.

After kneading with a mixer, the mixture is put into a steel mold and subjected to vibration compaction while being pressurized at 0.2 to 0.4 MPa, for example. , Forced re-arrangement of coarse aggregate is done,
It is possible to obtain a cured product of the hydraulic composition in which the bond between the coarse aggregates is increased and the structure is dense. Furthermore, the vibration is
By vibrating at a high frequency, the cement paste temporarily exhibits fluidity and concentrates in the vicinity of the contact point of the aggregate to be integrated, whereby the aggregates are firmly bonded to each other. It should be noted that unlike the conventional case, the cement paste does not separate from the coarse aggregate and flow out to the bottom of the mold.

Conventionally, fine aggregates having a particle size of less than 5 mm have been added to aggregates. However, in the present invention, it is not necessary to use such fine aggregates. The continuous voids will not be blocked.

Then, the cured body of the obtained hydraulic composition is aged at 0 to 30 ° C. under normal pressure, and then the carbonized gas discharged from the cement firing kiln or the boiler for curing is used for 3 times.
High-strength porous concrete molding for planting that neutralizes alkaline components that adversely affect the growth of plants by curing at 0-80 ° C in an atmosphere containing 5 to 20% carbon dioxide under normal pressure. The body is manufactured.

For such carbonation, combustion gas discharged from a cement burning kiln or a boiler for curing can be used, and these waste gases can be effectively used. By carbonating with such a gas, by heating under pressure carbonation in some cases, the alkaline components contained in the hardened body in the hydraulic composition, which adversely affects the growth of plants, are sufficiently neutralized and planted. A porous concrete molded body that can be effectively used for is obtained.

By such carbonation, the porous concrete molding for planting of the present invention has a porosity of 26% or more, a water permeability coefficient of 2.0 cm / sec or more, and a compressive strength of 30 N / mm ^2.
A porous concrete molding for planting having the above-mentioned performance is obtained. That is, in a region showing a high water permeability such as a porosity of 26% or more and a water permeability coefficient of 2.0 cm / sec or more,
The microstructure has a dense structure with a compressive strength of 30N.
/ Mm ² or more. This is because the slaked lime produced by hydration of the cement is carbonized and neutralized, so that the small pores change but the large continuous voids do not change. Is as high as 2.0 cm / sec or more and the compressive strength is 30 N
It is possible to obtain a high-strength porous concrete molded body of / mm ² or more.

The porous concrete for planting of the present invention is
The soil agent is used by injecting and filling the void portion, but the type of soil agent can be arbitrarily selected depending on the product cost and the type of plant to be vegetated. For example, peat moss, water treatment plant soil, perlite, mulch, zeolite, bentonite, and the like are used, but two or more of these may be used in combination.

[0037]

EXAMPLES The present invention will be described below with reference to Examples, Comparative Examples and Test Examples.
Will be described in more detail by, but is not limited to these examples
Not a thing.Preparation of hydraulic composition Cement: Ordinary Portland cement Inorganic powder: Blast furnace slag fine powder (Blaine value 4200c
m^Two/ G, specific gravity 2.90) Fine aggregate: No. 7 silica sand (specific gravity 2.60) Coarse aggregate: Crushed siliceous sandstone with a grain size of 13-5 mm (specific gravity 2.6
6, actual rate 60.0%) Dispersant: Polycarboxylic acid type high performance AE water reducing agent

A hydraulic composition was prepared by using the above materials and kneading in the proportions shown in Table 1 by the following method.

[0039]

[Table 1]

Specifically, the above-mentioned types of cement, blast furnace slag and water, and optionally fine aggregate are added, and the cement paste (or mortar) is kneaded, and then charged into a biaxial type mixer together with the coarse aggregate. Then, the mixture was kneaded for 1 minute, and the kneaded hydraulic composition was packed in a steel mold for molding. The mold was fixed to a vibrating table having a vibration frequency of 83 hertz and an amplitude of 0.75 mm, and the pressure was set to 0.3 MPa to perform pressure vibration compaction.

After compaction under pressure and vibration, the mixture was allowed to stand in a thermostatic chamber at 20 ° C. for 24 hours, then the form was removed and the combustion gas for curing was drawn into the curing chamber.
% Carbon dioxide gas atmosphere, and cured at atmospheric pressure to obtain a porous concrete compact. By curing in such a carbon dioxide gas atmosphere, the strength of the porous concrete molded body could be increased without deteriorating the water permeability function.

Regarding each of the obtained porous concrete molded bodies, the water permeability is the permeability test method 5-3-5 of the Pavement Test Method Handbook ((Japan) Japan Road Association), and the porosity is the pavement test method Handbook ((Company). ) The test was conducted according to the continuous porosity measuring method 1-1-4T of the Japan Road Association). Further, the compressive strength test was carried out according to JIS A1108 by using a cylindrical specimen with a diameter of 100 mm and a height of 200 mm in a predetermined material example (28 days).
(Compressive strength test method for concrete).

Further, each porous concrete was crushed with a crusher using the above-mentioned test body after the measurement of the porosity and the compressive strength, and a 1% aqueous solution of phenolphthalein was sprayed to determine whether or not it was alkaline. confirmed. In addition, in order to observe the growth of the plant in the concrete voids, soil material (humus) and alfalfa seeds were injected, and the vegetation state after 2 months was observed. The test results obtained are shown in Table 2.

[0044]

[Table 2] 〇 Plants with a height of 5 cm or more, △ Plants with a length of 3 cm or more, × Plant height of less than 3 cm

From Table 2, it can be seen that the porous concretes of the present invention of Examples all have a high water permeability of 2.0 cm / sec or more in terms of water permeability and a compressive strength of 30 N / mm ² or more. In Examples 5 to 7, it can be seen that the vegetation is poor because it is alkaline because it is not carbonated.
Further, in Comparative Examples 1 and 2, the amount of cement was small, so that it was neutral and the vegetation state was good, but the strength was low. Further, in Comparative Examples 3 and 4, the ratio of cement paste / aggregate is high, so that the porosity is poor, and since it is alkaline, the vegetation state is poor. As described above, none of the comparative examples could realize the high numerical values of the present invention in both the water permeability and the compressive strength.

[0046]

EFFECT OF THE INVENTION The planted porous concrete molded product of the present invention has an extremely high water permeability and a compressive strength applicable as an ordinary structural member or pavement member. By carbonating the water, the alkaline components that are bad for plant growth are neutralized,
It can be effectively used for cultivation of plants.

Further, the method for producing a plantable porous concrete molding of the present invention enables the plantable porous concrete molding of the present invention to be produced efficiently and economically.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) E02D 17/20 102 C04B 14:02 Z // (C04B 28/00 14:06 Z 14:02 14:04 Z 14:06 14:28 14:04 14:34 14:28 18:10 A 14:34 18:14 A 18:10 22:06 A 18:14 24:26 H 22:06 111: 40 24:26 ) B28B 1/08 B 111: 40 F term (reference) 2B027 NB03 NC02 NC17 NC42 NC51 2D044 DA15 4G012 PA02 PA03 PA04 PA10 PA13 PA26 PA29 PB04 PB32 PC02 PC03 PC11 PC12 PE04 PE07 RA02

Claims (5)

[Claims] 1. A hardened product of a hydraulic composition containing cement, coarse aggregate, water and a dispersant, wherein the alkali component is neutralized by carbonation with carbon dioxide gas, and the porosity is Of 26% or more, water permeability of 2.0 cm / sec or more, and compressive strength of 30 N / mm ² or more. 2. The porous concrete molded product for planting according to claim 1, further comprising an inorganic powder. 3. The porous concrete molding for planting according to claim 1, wherein 1 to 5 parts by weight of the dispersant and 7 to 20 parts by weight of water are used with respect to 100 parts by weight of the total amount of the cement and the inorganic powder. 3. The planting porous concrete molding according to claim 1 or 2, characterized in that it is mixed in an amount of 35 parts by volume with respect to the volume of the coarse aggregate. 4. In producing the porous concrete molding for planting according to any one of claims 1 to 3, a hydraulic composition containing cement, coarse aggregate, water and a dispersant is charged into a mixer. A method for producing a porous concrete molded body for planting, comprising the steps of: kneading and kneading, then charging into a mold, pressure vibration molding, and then curing with carbon dioxide gas. 5. The method for producing a porous concrete molded body for planting according to claim 4, wherein the carbon dioxide curing is performed at a temperature of 3
A method for producing a porous concrete molding for planting, which is carried out at 0 to 80 ° C. in an atmosphere containing 5 to 20% carbon dioxide.