JP2005112684A - Porous concrete and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high-strength and high void-ratio porous concrete without increasing its production cost by permitting the inside voids in concrete to expand without heating or heat treatment. <P>SOLUTION: The porous concrete is porous concrete which has continuous voids 32 in its inside and to which a weatherable solid 34 which spontaneously dissolves without being heated to form voids 33 between it and a coarse aggregate 30 or a cemental binder 31 is added. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to porous concrete mainly used as a concrete block for civil engineering structures and a method for producing the same.

  In recent years, porous concrete has attracted attention as a concrete material for reducing the environmental load. This porous concrete is porous concrete with continuous voids, and since it has the property that water and air can freely pass through the continuous voids, a purification function that naturally purifies the water quality by microorganisms living inside the concrete and the external surface, It has various excellent properties such as a vegetation function for rooting plants in soil filled in the continuous gap and a sound absorbing function for absorbing and absorbing sound waves into the continuous gap.

  Such porous concrete is usually produced by kneading a coarse aggregate and a cement paste prepared in a substantially single particle size with a predetermined composition, and driving the mixture into a mold to cure and harden. It is designed to have a predetermined porosity and strength by adjusting the weight ratio of the coarse aggregate and the cement paste, the water cement ratio (W / C), the particle size distribution of the coarse aggregate, or the like. However, in the case of mixing the coarse aggregate with the cement paste in this way, the particle size of the coarse aggregate may be increased in order to improve the porosity of the porous concrete, but if the particle size is too large This time, the contact area between the coarse aggregates becomes small, resulting in a contradiction that the strength of the porous concrete after hardening decreases.

Therefore, conventionally, a method for producing porous concrete (patent document 1) in which a piece of wood is mixed and cured in fresh concrete made of a mixture of coarse aggregate and cement paste, and the piece of wood is burned off after hardening of the concrete, There has been proposed a method for producing porous concrete (patent document 2) in which a meltable substance such as wax is blended with the above-mentioned fresh concrete and heated and cured. And according to these manufacturing methods, since some mixed materials (melting substances such as wood chips and wax) constituting the fresh concrete disappear after curing, the porosity of the porous concrete without reducing the concrete strength so much. Can be improved.
JP 2001-322878 A (Claim 1) JP-A-11-322464 (Claim 1)

  However, in the conventional method for producing porous concrete, a melting material such as a piece of wood or wax is used as an additive to fresh concrete made of a mixture of coarse aggregate and cement paste, so that it hardens to burn down the piece of wood. It is necessary to heat and cure the concrete in order to heat the concrete afterwards or to melt a melting substance such as wax. For this reason, in the conventional manufacturing method of porous concrete, since heating or a heating facility and a utility cost are required for the concrete, there is a drawback that the manufacturing cost increases.

  In view of such a conventional problem, the present invention is capable of expanding the voids in the concrete without heating or heating treatment, and has high strength and porosity without increasing the manufacturing cost. The purpose is to obtain large porous concrete.

In order to achieve the above object, the present invention takes the following technical means.
That is, in the present invention, in the porous concrete in which continuous voids are formed inside, a weathered solid that dissolves naturally without heating and forms a gap with the coarse aggregate or cement-based binder is blended. It is characterized by that.
According to the present invention, the weathered solid compounded in the concrete together with the coarse aggregate naturally dissolves without heating and has a property of forming a gap with the coarse aggregate or cement binder. Therefore, the continuous voids in the concrete can be expanded without heating or heating the fresh concrete or the hardened concrete.

  Specifically, the weathered solid can be composed of an artificial aggregate produced by kneading a water-soluble organic binder into a granular material containing earth or sand or clay and drying and solidifying it. . The granular material in this case can be composed of clay materials such as snake-meat clay, bentonite and kibushi clay, or fine-grained materials such as mountain sand, river sand, silica sand, and masa soil, or a combination thereof. If a clay material (inorganic binder) such as clay, bentonite, and kibushi clay is included, the moldability of the artificial aggregate can be improved.

  Of these clay materials, snake clay has the advantages of moderately plasticity, low firing shrinkage, uniform shrinkage, and difficulty in cracking, but iron and organic matter are less than Kibushi clay. There is a drawback that it is difficult to dissolve in water because it is small. Further, bentonite has a high compressive strength and a high swelling property, so that it may be clogged in the gap and difficult to dissolve. On the other hand, Kibushi clay is rich in water because it contains a lot of organic matter, it does not swell when dissolved in water, it is hard to cause clogging, and the plasticizer is very high. There is an advantage that it is easy to mold. For this reason, Kibushi clay is most suitable as the main component of the granular material constituting the artificial aggregate.

  On the other hand, as the water-soluble organic binder to be kneaded at the time of forming the artificial aggregate, starch binder, saccharide binder, synthetic resin binder, etc. can be employed. In addition, starch binder is recommended as it is highly water-soluble and has little adverse effect on the soil after dissolution and is environmentally friendly. There are two types of starch binders, starch and dextrin, and dextrin is recommended because of its high caking property at low moisture. Therefore, dextrin is most suitable as the main component of the organic binder constituting the artificial aggregate.

In the present invention, the weathered solid may be composed of a water-absorbing polymer having a property of being dissolved in an alkaline aqueous solution. Specific examples of such a polymer include, for example, a crosslinked sodium salt of an acrylic acid polymer. Can be mentioned.
In this case, water is absorbed by the water-absorbing polymer at the initial stage of curing of the fresh concrete and the polymer swells, but the calcium ions eluted when the cement binder is cured binds to the water-absorbing polymer. Moisture is discharged to the outside. For this reason, the water-absorbing polymer shrinks during the curing process of the cement binder and its volume becomes extremely small, and the continuous voids inside the porous concrete after curing are expanded.

Furthermore, in the present invention, the weathered solid may be composed of a hollow aggregate composed of a hollow body having an opening and a water-soluble membrane that closes the opening of the hollow body.
In this case, in the initial stage immediately after the hardening of the porous concrete, the opening of the hollow body is closed with a film body, but when the hollow aggregate in the porous concrete is exposed to rainwater or the like that has entered the continuous void, The aggregate film is gradually dissolved to open the opening of the hollow body, and the continuous void inside the porous concrete is expanded.

The specific shape of the hollow body is not particularly limited. However, if a cylindrical member having openings at both ends in the axial direction is used, a uniform shape can be obtained simply by cutting the pipe material into a certain axial length. The hollow body can be easily produced, and the manufacturing cost can be reduced in this respect. Moreover, as a constituent material of the water-soluble film body constituting the hollow body, for example, the dextrin can be employed.
In order to actually manufacture the porous concrete of the present invention, the coarse aggregate and weathered solid are uniformly mixed with a cement-based binder to produce a fresh concrete having a predetermined composition, and this concrete is poured into a formwork and cured. You can do it.

  However, since the porous concrete of the present invention contains weathered solids that dissolve naturally without heating, most of the weathered solids dissolve in the uncured stage if the moisture content of the fresh concrete is too large. There is a possibility that the porosity of porous concrete cannot be improved. In addition, if the difference in specific gravity between coarse aggregate and weathered solid is large, only weathered solid will be concentrated and unevenly distributed, resulting in unnecessarily large voids and reduced strength of the porous concrete. There is also a fear of doing.

Therefore, in order to produce the porous concrete of the present invention, a weathered solid that dissolves naturally without heating and a coarse aggregate are mixed with a cement-based binder to produce ultra-kneaded fresh concrete, which is then used as a formwork. It is preferable to employ a so-called immediate demolding method in which the mold is immediately demolded by applying vibration to the same mold after filling.
According to such an immediate demolding method, fresh concrete made by mixing coarse aggregate and weathered solids with cement-based binder is super-kneaded with zero slump with very low water content. The weathered solids are hardly dissolved in the uncured stage, and it is possible to prevent a decrease in the porosity of the porous concrete due to the dissolution of the weathered solids before the curing.

  In addition, according to the above-mentioned immediate demolding method, since the ultra-solid kneaded fresh concrete is filled into the mold, the mold is vibrated and immediately demolded, so that coarse aggregate, weathered solids and Even if the difference in specific gravity is relatively large, only weathered solids will not be concentrated and unevenly distributed, so that it is possible to prevent the strength of porous concrete from being lowered due to the formation of voids that are larger than necessary. Can do.

  As described above, according to the present invention, since the continuous voids in the porous concrete can be expanded without heating or heating treatment, the porous concrete has high strength and high porosity without increasing the manufacturing cost. Can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a composite porous block 1 with a hole having porous concrete according to the present invention. The porous block 1 in this case is used for greening a slope such as a river dike or a roadside retaining wall. The slope greening block 1A.
The slope greening block 1A includes a thick plate-like block main body 2 having a square shape in plan view. The block main body 2 superposes and joins square-shaped porous concrete and ordinary concrete having substantially the same thickness. Thus, a two-layer structure is formed in which the front surface side is a porous concrete layer 3 and the back surface side is a normal concrete layer 4.

On the surface of the block body 2, a plurality of storage recesses 5 that are recessed in the thickness direction from the surface of the block body 2 are formed so that the vegetation soil can be stored inside. A total of four storage recesses 5 are provided on the four corners of the block body 2, and are formed by circular grooves having a depth approximately half the thickness of the block body 2.
A storage hole 6 communicating with the bottom of the storage recess 5 is formed inside the block body 2 so as to extend in the in-plane direction of the block body 2. The storage hole 6 is formed so as to penetrate the block body 2 from one end surface in the width direction to the other end surface of the block body 2. The storage hole 6 is a circular hole having a circular cross section and extending straight, and a total of two holes are provided.

Each of the two storage holes 6 is disposed at a planar position passing through the central portions of the two upper and lower storage recesses 5 adjacent to each other, and the cross-sectional centers of the storage holes 6 are the porous concrete layer 3 and the ordinary concrete layer 4. It is arranged at a position in the thickness direction having the same depth as the joint surface. Each of the storage holes 6 is set to have a cross-sectional dimension that can be filled with a water retaining material made of soil, coconut shell, or the like.
The slope greening block 1A according to the above configuration is constructed so as to cover the slope by, for example, installing it side by side on the slope of an existing concrete retaining wall (not shown). . And, for example, by planting a plant such as grass in the soil that is stored in the storage recess 5 with the water retaining material filled in the storage holes 6 of each block 1, the slope of the concrete retaining wall is greened. can do.

4 and 5 are enlarged sectional views showing an example of the internal structure of the porous concrete layer 3.
The porous concrete shown in FIGS. 4 and 5 is one in which a continuous void 32 is formed inside by combining the coarse aggregate 30 with a cement-based binder 31 made of ordinary Portland cement or the like. In addition to the coarse aggregate 30, a weathered solid 34 is blended that naturally dissolves without heating to form a new gap 33 with the coarse aggregate 30 or the cement-based binder 31.

  Among the porous concretes shown in FIGS. 4 and 5, in the porous concrete shown in FIG. 4, as the weathered solid matter 34, a water-soluble organic binder is kneaded into a granular material containing earth and sand, clay, etc., and dried and solidified. The artificial bone material 35 manufactured by making it be used is adopted. When the artificial aggregate 35 has a particle size that is too large compared to the coarse aggregate 30, the strength of the porous concrete is reduced. On the contrary, if the particle size is too small, the porosity cannot be improved much. At most, it is recommended to set the particle size to approximately the same size as that of the coarse aggregate 30, more preferably about half the particle size of the coarse aggregate 30. Therefore, for example, when the particle size of the coarse aggregate 30 is 5 mm to 15 mm (corresponding to No. 6 crushed stone), the particle size of the artificial aggregate 35 may be set to 3 mm to 10 mm.

  In addition, as the granular material constituting the artificial aggregate 35, clay materials such as snake-meat clay, bentonite and kibushi clay, or fine-grained materials such as mountain sand, river sand, silica sand and masa soil, or combinations thereof are used. Although it can employ | adopt, in this embodiment, what mix | blended Kibushi clay as a main component is employ | adopted. On the other hand, as the water-soluble organic binder to be kneaded into the artificial bone 35, starch binder, saccharide binder, synthetic resin binder, and the like can be employed. The main component is dextrin, which is highly caustic in moisture, rich in water solubility, and has little adverse effect on the soil after dissolution.

On the other hand, in the porous concrete shown in FIG. 5, a hollow aggregate 36 is employed as the weathered solid material 34. The hollow aggregate 36 includes a hollow body 37 having an opening and a water-soluble film body 38 that closes the opening of the hollow body 37. The hollow body 38 of the present embodiment is open at both axial ends. It consists of a short cylindrical member having a portion. The short cylindrical hollow body 38 is manufactured by cutting a pipe material such as a steel pipe or a hard PVC pipe into a predetermined axial length.
The film body 38 is configured by immersing the opening of the hollow body 37 in liquid dextrin, closing the opening with the dextrin, and drying and curing the opening. The hollow body 37 constituting the hollow aggregate 36 is not limited to a cylindrical shape with both ends open, and may be a cylindrical shape or hemispherical shape with only one end open. Also, in the hollow aggregate 36, for the same reason as in the case of the artificial aggregate 35, at most the same size as that of the coarse aggregate 30, more preferably about half of the coarse aggregate 30. It is recommended to set the diameter.

  4A shows a state before the artificial aggregate 35 in the porous concrete is dissolved, and FIG. 4B shows a state after the artificial aggregate 35 in the concrete is dissolved. As can be seen from FIGS. 4 (a) and 4 (b), when the artificial aggregate 35 in the porous concrete is exposed to rainwater or the like that has entered the continuous gap 32, the powder gradually dissolves and flows out to the outside. A gap 33 is newly formed between the coarse aggregate 30 and the cement-based binder 31, and the continuous void 32 inside the porous concrete is expanded.

  FIG. 5A shows a state before the film body 37 of the hollow aggregate 36 in the porous concrete is dissolved, and FIG. 5B shows the film body 37 of the hollow aggregate 36 in the concrete. The later state is shown. As can be seen from FIGS. 5A and 5B, in the initial stage immediately after the hardening of the porous concrete, the opening of the hollow body 37 is closed by the film body 38, but the hollow aggregate 36 in the porous concrete is closed. When exposed to rain water or the like that has entered the continuous gap 32, the film body 38 of the aggregate 36 gradually dissolves and the opening of the hollow body 37 is opened. For this reason, a gap 33 is newly formed between the hollow aggregate 36 and the coarse aggregate 30 or the cement binder 31, and the continuous void 32 inside the porous concrete is expanded.

As described above, according to the porous concrete of the present embodiment, the weathered solid 34 mixed in the concrete together with the coarse aggregate 30 is naturally melted without heating and between the coarse aggregate 30 or the cement-based binder 31. Therefore, the continuous void 32 inside the concrete can be expanded without heating or heating the fresh concrete or the hardened concrete. For this reason, it is possible to obtain porous concrete having high strength and a high porosity without increasing the manufacturing cost.
In addition, as the weathering solid substance 34 which melt | dissolves naturally by non-heating and forms the new space | gap 33, not only the said artificial aggregate 35 and the hollow aggregate 36 but the water-absorbing polymer (the property which melt | dissolves in alkaline aqueous solution ( For example, it may be constituted by an acrylic acid polymer partial sodium salt cross-linked product).

  If such an alkali-soluble water-absorbing polymer is added to porous concrete, water is absorbed by the water-absorbing polymer at the initial stage of curing of the fresh concrete, and the polymer swells, but is eluted when the cement-based binder is cured. When the calcium ions are bound to the water-absorbing polymer, the water is discharged to the outside. For this reason, the water-absorbing polymer shrinks during the curing process of the cement binder and its volume becomes extremely small, and the continuous voids inside the porous concrete after curing are expanded.

Next, with reference to FIG.2 and FIG.3, the manufacturing method of this embodiment which manufactures the said slope greening block 1A with an immediate demolding construction method is demonstrated.
First, as shown in FIG. 2A, a steel mold 11 that can be used repeatedly is set on a vibration table 10 that is supported by a rubber vibration-proof leg 8 and has a vibrator 9 on the lower surface side. An uncured porous concrete 12 is filled into the frame 11. The uncured porous concrete 12 is a fresh concrete prepared by super-kneading zero slump by mixing the weathered solid material 34 and the coarse aggregate 30 which are naturally dissolved without heating into a cement binder 31. It becomes more.

  The steel mold 11 is composed of a square cylindrical side wall 13 opened on both upper and lower sides, and a bottom plate 14 placed on a mounting flange projecting inward from the lower end of the side wall 13. 14 is provided with a cylindrical protrusion 15 for molding the storage recess 5. Further, a core 16 for molding the storage hole 6 is attached to the steel mold 11. The core 16 is made of a rod-shaped member (for example, a round steel pipe) having a circular cross section, and is moved to a round hole formed in the opposite side wall 13 of the mold 11 so that it can be inserted and removed along its axial direction. It is inserted freely. Therefore, by inserting and removing the core 16 made of a rod-shaped member toward the side wall 13, the core 16 can be detached from the mold 11 from the outside.

Next, as shown in FIG. 2 (b), the core 16 is filled with almost half of the porous concrete 12 which includes the weathered solid material 34 in addition to the coarse aggregate 30 and is super-kneaded with zero slump. The mold 11 is filled at a depth, and the vibrator 9 is operated while pressing the upper surface of the porous concrete 12 with a press 17, and the vibration table 10 is vibrated until the concrete 12 becomes fluid.
After that, as shown in FIG. 3A, zero-slump super hard kneaded uncured ordinary concrete 18 is filled into the mold 11 until the upper edge of the side wall 13 is filled, and the upper surface of this ordinary concrete 18 is filled. The vibrator 9 is operated while being pressed by the press 17, and the vibration table 10 is vibrated until the concrete 18 is fluid.

  After the vibration of the vibration table 10 is finished, as shown in FIG. 3B, the mold 11 is turned upside down with the upper opening closed by the cover plate 19, and the core 16 is moved in the axial direction. And slowly pulling it out of the form 11. Thereafter, the side wall 13 of the mold 11 is pulled upward, the bottom plate 14 is removed, and the concrete molded body thus demolded from the mold 11 is cured and cured at a predetermined temperature. The manufacture of the slope greening block 1A is completed.

As described above, in this embodiment, the weathered solid matter 34 and the coarse aggregate 30 that are naturally dissolved without heating are mixed with the cement-based binder 31 to produce the zero slump ultra-solid kneaded fresh concrete 12. Since the immediate demolding method of applying vibration to the mold 11 after filling 12 into the mold 11 is adopted, the weathered solid 34 may be dissolved when the cement binder 31 is uncured. Almost no reduction in the porosity of the porous concrete due to the dissolution of the weathered solid matter 34 prior to its hardening can be prevented.
Further, according to such an immediate demolding method, the ultra-solid kneaded fresh concrete 12 is filled in the mold 11 and then the mold 11 is vibrated and immediately demolded. Therefore, the coarse aggregate 30 Even when the difference in specific gravity between the weathered solid material 34 and the weathered solid material 34 is relatively large, only the weathered solid material 34 is not concentrated and unevenly distributed, so that an unnecessarily large space is formed and the strength of the porous concrete is reduced. Can be prevented beforehand.

Furthermore, according to the manufacturing method of the present embodiment, the core 16 is taken out from the mold 11 immediately before the concrete molded body is immediately removed from the mold 11, so that the housing hole 6 can be easily and cleanly formed without breaking. be able to. Further, since a core 16 made of a straight rod-like member that penetrates the side wall 13 of the mold 11 is adopted so that it can be inserted and removed along the axial direction, the core 16 is immediately inserted immediately before demolding. There is an advantage that the core 16 can be removed from the mold by simply pulling it straight out from the side wall 13 of the mold 11 along the axial direction, and the core 16 can be taken out very easily.
In addition, according to the manufacturing method of the present embodiment, since the normal concrete 18 is filled after the porous concrete 12 is filled and pressurized and vibrated, the porous concrete 12 once compacted by the pressurized vibration is used. Since ordinary concrete 18 is filled on top, the ratio of mixing both concrete 12 and 18 during the final pressure vibration is reduced, and the joint surface of both concrete 12 and 18 appears more clearly. There is also an advantage that a high slope greening block 1A can be obtained.

In addition, all the said embodiment is illustrations and is not restrictive. The scope of the present invention is defined by the claims, and all modifications within the scope equivalent to the configurations described therein are also included in the present invention.
For example, in the said embodiment, the porous concrete of this invention containing a weathering solid substance is manufactured by the immediate demolding method, However, The said porous concrete of this invention can also be manufactured by a normal concrete filling method.
Moreover, the porous concrete of this invention can be employ | adopted not only for the composite porous block 1 with a hole shown in FIG. 1, but the block for civil engineering construction which has other various shapes thru | or structures.

  In order to demonstrate the usefulness of the present invention, the porous concrete (Examples 1 and 2) of the present invention containing coarse aggregate and weathered solids and the normal porous concrete not containing weathered solids (Comparative Example) And then, after continuing to spray them with sufficient moisture, their compressive strength and porosity were compared. In addition, the mixing | blending of each Example and a comparative example is as showing in following Table 1.

Moreover, among the porous concrete of this invention, the weathering solid 1 used in Example 1 and the weathering solid 2 used in Example 2 dry-solidify the binder kneaded with the following weight composition, respectively. It is an artificial aggregate produced by
(Weathered solid 1)
Kibushi clay: dextrin: water = 3: 1: 2
(Weathered solid 2)
Masa soil: Kibushi clay: Dextrin: Water = 9: 3: 1: 2.5

  As a result, the compressive strengths of Example 1, Example 2, and Comparative Example were 17.3 (N / mm 2), 18.6 (N / mm 2), and 19.6 (N / mm 2), respectively, and weathered solids. Even when the products 1 and 2 were contained, the compressive strength was hardly lowered. On the other hand, the porosity of Example 1, Example 2 and the comparative example is 30%, 30% and 25%, respectively, and when the weathered solids 1 and 2 are contained, the porosity is greatly improved. did. Therefore, it has been clarified from the experimental results that according to the present invention, porous concrete having high strength and high porosity can be obtained.

(A) is a perspective view of a slope greening block, (b) is a plan view of the block, and (c) is a side sectional view of the block. It is process explanatory drawing which shows the manufacturing method of a composite porous block with a hole. It is process explanatory drawing which shows the manufacturing method of a composite porous block with a hole. It is an expanded sectional view which shows an example of the internal structure of a porous concrete layer, (a) is a state before the artificial aggregate in porous concrete melt | dissolves, (b) is after the artificial aggregate in the concrete melt | dissolved Indicates the state. It is an expanded sectional view which shows an example of the internal structure of a porous concrete layer, (a) is a state before the film body of the hollow aggregate in porous concrete melt | dissolves, (b) is the film | membrane of the hollow aggregate in the concrete The state after the body is dissolved is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Formwork 12 Fresh concrete 30 Coarse aggregate 31 Cement-type binder 32 Continuous space | gap 33 Space | gap 34 Weathered solid matter 35 Artificial aggregate 36 Hollow aggregate 37 Hollow body 38 Film body

Claims (9)

  Weathered solid that forms a gap (33) between coarse aggregate (30) and cementitious binder (31) in porous concrete in which continuous voids (32) are formed. Porous concrete characterized in that a product (34) is blended.   The weathered solid (34) comprises an artificial aggregate (35) produced by kneading a water-soluble organic binder into a granular material containing earth and sand or clay and drying and solidifying it. Porous concrete.   The porous concrete according to claim 2, wherein the granular material contains kibushi clay as a main component.   The porous concrete according to claim 2 or 3, wherein the organic binder contains dextrin as a main component.   The porous concrete according to claim 1, wherein the weathered solid (34) comprises a water-absorbing polymer having a property of being dissolved in an alkaline aqueous solution.   The porous concrete according to claim 5, wherein the water-absorbing polymer comprises a crosslinked sodium salt of an acrylic acid polymer.   The weathered solid (34) is composed of a hollow aggregate (36) comprising a hollow body (37) having an opening and a water-soluble film body (38) closing the opening of the hollow body (37). The porous concrete according to claim 1.   The porous concrete according to claim 7, wherein the hollow body (37) is formed of a cylindrical member having openings at both ends in the axial direction.   A non-heated weathered solid (34) and coarse aggregate (30) are mixed with cement-based binder (31) to produce zero slump ultra-solid kneaded concrete (12). The method for producing porous concrete according to any one of claims 1 to 8, wherein 12) is filled in the mold (11), and then the mold (11) is vibrated and immediately demolded.

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