JP3290171B2 - Manufacturing method of porous concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing porous concrete having high porosity and excellent water permeability.

[0002]

2. Description of the Related Art Porous concrete has a high porosity and is therefore mainly used as a permeable concrete for pavement materials such as roadways. When porous concrete is used, rainwater is easily transmitted even during rainfall, and the safety can be improved by preventing the hydroplane phenomenon of the traveling vehicle and preventing water splash to improve poor visibility. It also has the effect of reducing noise.

Recently, porous concrete has attracted attention as a material that can be harmonized with or coexist with an ecosystem, that is, an eco-material. I have.

[0004] Such porous concrete is generally made of an inorganic binder such as cement, approximately 15 to 30 parts by weight of water with respect to 100 parts by weight of the powder, coarse aggregate, and if necessary, fine aggregate. By kneading the aggregate and the dispersant, it is manufactured by uniformly coating the coarse aggregate and the cement paste (or mortar).

[0005] The produced porous concrete is directly driven into a mold having a predetermined shape or into a predetermined place partitioned by a mold or the like, and is vibrated from the surface or the side by an external vibrator to be compacted. Molded.

[0006] However, when the porous concrete is vibrated by the vibrator as described above, the cement paste or mortar easily flows down to the bottom and blocks the void portion. In such a case, the hydraulic conductivity at the bottom of the molded article is significantly reduced,
In the upper part of the molded product, the amount of the paste or mortar becomes insufficient, and the components become non-uniform as a whole, which tends to cause a decrease in strength.

Conventionally, in order to solve such a problem, a surfactant is added to reduce the unit water amount, and the aggregate has a particle diameter of 5 m.
m, and a method for producing porous concrete by adding fine aggregate of less than m (JP-A-7-206537), and further reducing the amount of water.
A method for producing porous concrete with a reduction to 19% (JP-A-11-268969) is disclosed.

However, according to the former method, there is a problem that the strength with respect to the hydraulic conductivity is low, that is, in order to secure the strength, the hydraulic conductivity must be reduced. On the other hand, according to the latter method, the strength with respect to the hydraulic conductivity is high, but it is necessary to knead a cement paste having an extremely small water-powder ratio, so that the kneading time of the paste becomes longer and the production efficiency of the porous concrete decreases. In addition, there is a problem that the material cost increases because the unit powder amount increases.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing porous concrete that can be easily and economically produced while maintaining high water permeability and strength.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of the above-mentioned problems, and found that a high-performance AE water reducing agent and an admixture having poor compatibility with the high-performance AE water reducing agent are used in combination.
The inventors have found that these problems can be solved, and have completed the present invention.

That is, a means of the present invention is to provide a kneaded material in which a cement paste or mortar is added to coarse aggregate and kneaded, and the surface of the coarse aggregate is coated with the cement paste or mortar. In the method for producing a porous concrete which is put into a mold and cured, a high-performance AE water reducing agent and an admixture poorly compatible with the high-performance AE water reducing agent are added to the kneaded material. To produce porous concrete.

[0012] Here, the admixture having poor compatibility with the high-performance AE water-reducing agent is one that causes a flocculation phenomenon and deteriorates fluidity when kneaded in a cement paste or mortar with the high-performance AE water-reducing agent. Say.

[0013] Between the input and the curing, the frequency of 200
It is preferable to perform vibration compaction at 0 to 12000 vpm and amplitude of 0.2 to 2.0 mm.

[0014] When a high-performance AE water reducing agent and an admixture having poor compatibility with the high-performance AE water reducing agent are added, stiffness is caused by the coagulation phenomenon, and the viscosity of the cement paste or mortar can be effectively increased. It can be prevented from peeling off and flowing down. In addition, the aggregation phenomenon can be temporarily disintegrated by applying high-frequency vibration as described above (that is, exhibiting thixotropic properties).
For this reason, if necessary, high-frequency vibration is applied and fluidized after being put into the mold to compact the fluid, and then the vibration is stopped and coagulated again to maintain good properties of the porous concrete.

When the admixture is not a thickener, the total amount of the high-performance AE water-reducing agent and the admixture is 0.5 to the powder material constituting the cement paste or the mortar. Preferably, the content of the high-performance AE water reducing agent or admixture is 20% by weight or more based on the total amount.

Further, when the admixture is a thickener, the amount of the high-performance AE water reducing agent to be added to the cement paste or the powder material constituting the mortar is 1 to 5%.
7% by weight, and the amount of the admixture added is 0.2 to 2.
Preferably it is 5% by weight.

Here, the powder material constituting the cement paste or the mortar is, in the case of a cement paste, a simple substance of cement or a material obtained by adding an admixture or the like thereto. It includes fine aggregate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method for producing porous concrete according to the present invention will be described. First, a cement paste or mortar is prepared by adding water to a binder composed of cement and an admixture added as necessary, and further adding fine aggregates as needed, and kneading. At this time, a high-performance AE water reducing agent and an admixture having poor compatibility with the high-performance AE water reducing agent are added and kneaded together with the cement paste or mortar. Further, a coarse aggregate is added to the cement paste or mortar and kneaded to prepare a kneaded material in a state where the surface of the coarse aggregate is covered with the cement paste or mortar. Thereafter, the kneaded material is put into a mold, subjected to vibration compaction, and then cured to form porous concrete.

As the high-performance AE water reducing agent, polycarboxylic acid-based, naphthalene-based, melamine-based, aminosulfonic acid-based and other high-performance AE water-reducing agents can be used.

Here, polycarboxylic acid-based high-performance AE water reducing agents include polycarboxylic acid ether-based composites, polycarboxylic acid-based compounds such as polycarboxylates, maleic acid copolymers, and maleic acid derivatives. Polymers and maleic acid-based compounds such as maleic ester copolymers as main components can be exemplified. Examples of the naphthalene-based high-performance AE water reducing agent include lignin derivatives and alkylallylsulfonic acid-based compounds. Examples of the melamine-based high-performance AE water reducing agent include those containing a modified methylol melamine condensate as a main component. Further, as the aminosulfonic acid-based high-performance AE water reducing agent, And those containing an aromatic sulfonic acid condensate and a lignin sulfonic acid derivative as main components.

On the other hand, the admixture having poor compatibility with the high-performance AE water reducing agent is, for example, a gel which is deteriorated in flowability due to an aggregation phenomenon when mixed with the high-performance AE water reducing agent. It is sufficient that the high performance A
Among the E water reducing agents, different types of high performance AE water reducing agents are used in combination, or water reducing agents poorly compatible with the high performance AE water reducing agents, AE water reducing agents, setting accelerators, setting retarders, Alternatively, a thickener or the like can be used. However, when different types of high-performance AE water reducing agents are used, combinations of naphthalene-based and aminosulfonic acid-based high-performance AE water reducing agents are excluded.

[0022]

When the admixture is not a thickener, the total amount of the high-performance AE water reducing material and the admixture is 0.5 to the cement paste or the powder material constituting the mortar. It is preferable that they are added so as not to be less than 20% by weight, more preferably not more than 30% by weight, based on the total amount.

If the total amount is less than 0.5% by weight, the paste or mortar hardly flows even when high frequency vibration is applied. On the other hand, if it exceeds 5% by weight, the paste or mortar becomes too fluid when high frequency is applied. Cement paste or mortar flows down easily. In addition, one of the two is 20
If it is less than 10% by weight, the degree of stiffness due to the aggregation phenomenon is weak, and it is difficult to obtain the properties intended by the present invention.

When the admixture is a thickener, the thickener and the high-performance AE water-reducing agent are each added to the cement paste or the mortar in an amount of from 0.2 to 0.2%. It is preferable to add 2.5% by weight and 1 to 7% by weight.

When the addition amount of the thickener is 0.2% by weight or less, the coagulating action with the high-performance AE water reducing agent is not sufficient, and
When it is set to 5% by weight or more, even when vibration is applied at a high frequency,
There is a risk of not exhibiting favorable fluidity, and this is uneconomical. On the other hand, when the addition amount of the high-performance AE water reducing agent is 1% by weight or less, the aggregation effect with the thickener is not sufficient, and
In this case, when the vibration is applied at a high frequency, the cement paste or the mortar may flow too much and the cement paste or the mortar may flow down, which is uneconomical.

The type of cement is not particularly limited, and general cements such as Portland cement and mixed cement specified in JIS can be widely used.

In place of part of the cement, admixtures such as blast furnace slag fine powder, fly ash, silica fume, limestone fine powder or silica stone fine powder, and fine aggregate can be mixed. The replacement rate in this case is 30%
It is preferable to set the following.

The unit water amount is appropriately adjusted in consideration of the grain system, particle size distribution, porosity, etc. of the coarse aggregate to be used, and it is generally 50 to 130 kg / m ^3. preferable.

The coarse aggregate serves as a skeleton of porous concrete, and those commonly used as coarse aggregate for concrete can be widely used.
Crushed stone, artificial lightweight aggregate, and the like can be used. Also,
The particle size and particle size distribution of the coarse aggregate affect the general properties of the porous concrete, such as the size of the void, the porosity, the strength, and the like, and can be freely selected depending on the application and purpose. Specifically, those having a size of about 5 to 80 mm, and particularly those having a size of 10 to 30 mm can be suitably used.

In the above-mentioned production, as a mixer used for kneading, a mixer used for ordinary kneading of concrete can be used, and among them, an omni type or forced kneading type mixer is preferable with good mixing efficiency.

As a kneading procedure, a so-called split system in which cement paste or mortar is kneaded in advance and then coarse aggregate is added and kneaded is preferable. Compared to a batch system in which all materials are kneaded and mixed simultaneously, The time required for uniformly covering the coarse aggregate surface with the cement paste or mortar can be reduced. The high-performance AE water reducing agent to be added in the present invention and the admixture that is incompatible with the high-performance AE water reducing agent can be made uniform by diluting them in mixing water beforehand in any case. easy.

After the introduction, the cement paste or mortar is temporarily fluidized, and the viscous compaction is performed in order to make the aggregates firmly settled by concentrating the paste or mortar on the portions where the aggregates come into contact with each other. It is preferred to do so. The vibration compaction is performed by using a high-frequency vibrator such as a form vibrator or a shaking table, at a frequency of 2000 to 12
2,000 vpm and amplitude of 0.2 to 2.0 mm
It is preferable to carry out for about 0 seconds.

The formed porous concrete is cured according to a conventional method such as underwater curing, wet-air curing, steam curing, or autoclave curing as required.

[0035]

The present invention will be described below in detail with reference to examples.

(Examples 1 to 4) Water, cement, coarse aggregate,
Porous concretes of Comparative Examples 1 to 4 were prepared with the admixture and the admixture. The following materials were used.

Cement: Ordinary Portland cement (density 3.15 g / cm ³ ) Coarse aggregate: Hard sandstone crushed stone having a particle size of 13 to 20 mm (surface dry density 2.69 g / cm ³ , actual volume 61.0%) Admixture: polycarboxylic acid -Based high-performance AE water reducing agent ("Leobuild PS-8S" manufactured by NMB) admixture: naphthalene-based high-performance AE water reducing agent ("Mighty 2000WH" manufactured by Kao Corporation)

Comparative Example 1 A porous concrete of Comparative Example 1 was prepared in the same manner as in Examples 1 to 4, except that only the admixture was used.

(Comparative Example 2) Comparative Example 2 was prepared in the same manner as in Examples 1 to 4, except that the following admixture having good compatibility with the above-mentioned admixture was used instead of the admixture. Admixture: Lignin-based AE water reducing agent ("Pozzolith No.7" manufactured by NMB)
0 ")

(Comparative Examples 3 to 5) Comparative Example 3 when the total amount of the admixture and the total amount was small, Comparative Example 4 when the total amount of the admixture and the total amount was large, and when one of the admixtures was 2
Comparative Example 5 was prepared as the case where the content was 0% by weight or less.

(Example 5) In place of the admixture, the following admixture having poor compatibility with the above-mentioned admixture was used. Prepared. Admixture: Cellulose-based thickener ("ASCEAN" manufactured by Shin-Etsu Chemical Co., Ltd.)

Comparative Example 6 Example 5 was prepared in the same manner as in Example 5 except that an admixture having good compatibility with the above-mentioned admixture was used instead of the admixture.

Example 6 A mortar was prepared by adding the following admixture and fine aggregate to cement, and the same procedures as in Examples 1 to 4 were used to prepare Example 6, except that the mortar was the same.

(Comparative Example 7) Example 7 was prepared in the same manner as in Example 6, except that an admixture having good compatibility with the above-mentioned admixture was used instead of the admixture.

Table 1 shows the amounts of Examples 1 to 6 and Comparative Examples 1 to 7.

[0046]

[Table 1] Materials other than the coarse aggregate are put into a biaxial forced kneading mixer at a time, and kneaded for 90 seconds to prepare a paste or mortar. Thereafter, coarse aggregate was charged and kneaded for 60 seconds to obtain porous concrete. The finished porous concrete was discharged from the mixer and packed in a steel mold for forming. The mold filled with the sample was fixed on a shaking table having a vibration frequency of 3000 vpm and an amplitude of 1.5 mm, and was subjected to vibration compaction for 5 seconds.

Curing and test method After compaction by vibration,
The mold was removed and curing was performed in water at 20 ° C. for 28 days.
Using the specimens of Examples 1 to 6 and Comparative Examples 1 to 7 thus obtained, the water permeability and the compressive strength were determined. The coefficient of permeability was determined in accordance with the “Permeability test method for porous concrete (draft)” proposed by the Eco-Concrete Research Committee of the Japan Concrete Institute, and the compressive strength was measured according to JIS.
A 1108 was carried out in accordance with “Method of compressive test for concrete”. Table 2 shows the results.

[0048]

[Table 2]

As shown in Table 2 above, in Examples 1 to 6 according to the present invention, the water permeability was 2.0 cm
/ Sec, high water permeability and over 20 N / m
It can be seen that a high compressive strength of at least m ² is obtained.

[0050]

As described above, according to the method for producing porous concrete according to the present invention, it is possible to produce porous concrete having excellent water permeability and high strength. In addition, in the production process, cement paste or mortar can be prepared with a normal amount of water, so that porous concrete can be easily and economically produced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C04B 24:22 C04B 24:38) D 24:38) 111: 40 111: 40 B28B 1/08 B (56) References JP JP-A-9-2882 (JP, A) JP-A-6-199560 (JP, A) JP-A-9-216218 (JP, A) JP-A-2000-119074 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 38/00-38/10 B28B 1/08 C04B 28/02

Claims (5)

(57) [Claims] Claims 1. A cement paste or mortar is added to a coarse aggregate and kneaded to form a kneaded material in which the surface of the coarse aggregate is coated with the cement paste or the mortar, and the kneaded material is put into a mold. A method for producing a porous concrete, comprising: adding a high-performance AE water reducing agent and an admixture incompatible with the high-performance AE water reducing agent to the kneaded material. . 2. A vibration frequency of 2 between the introduction and the curing.
The method for producing porous concrete according to claim 1, wherein vibration compaction is performed at 000 to 12000 vpm and amplitude of 0.2 to 2.0 mm. 3. When the admixture is not a thickener, the total amount of the high-performance AE water-reducing agent and the admixture is 0. 0 to the powder material constituting the cement paste or the mortar. The method for producing porous concrete according to claim 1 or 2, wherein the content is 5 to 5% by weight. 4. The high-performance AE water reducing agent and the admixture are at least 20% by weight based on the total amount of the high-performance AE water reducing agent and the admixture. 4. The method for producing a porous concrete according to any one of claims 1 to 3. 5. When the admixture is a thickener, the amount of the high-performance AE water reducing agent is 1 to 7% by weight based on the powder material constituting the cement paste or the mortar.
The method for producing porous concrete according to claim 1, wherein the amount of the admixture is 0.2 to 2.5% by weight.