JPH08199809A - Manufacture of concrete structure - Google Patents

Abstract

PURPOSE: To improve the surface property by placing the concrete in a form after the powder containing the hydraulic powder, the hydraulic mortar, etc., whose content and viscosity are specified is applied to the inside of the form, and specifying the grain size of the fine aggregate of the hydraulic mortar. CONSTITUTION: After water or mold lubricant is applied to the inner side of a form, the hydraulic powder is sprayed or applied, and then the concrete is placed in the form. The hydraulic paste or the hydraulic mortar is sprayed or applied to the inner surface of the form, and the concrete is placed in the form. The content of the powder, the hydraulic paste or the hydraulic powder in the hydraulic mortar is >=10wt.%, and the viscosity of the hydraulic paste and the hydraulic mortar is 100-20000mPa.S. In addition, the hydraulic mortar of <=2.5mm in grain size is used as the fine aggregate. The hardened surface layer is formed on the placed concrete, and holes generated by bubbles on the surface can be concealed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a concrete structure, and more particularly to a method for manufacturing a concrete structure for obtaining a concrete structure having a good surface property.

[0002]

2. Description of the Related Art A concrete structure manufactured at a construction site or a concrete product manufactured at a factory has a good surface quality by minimizing bubbles generated on the concrete surface due to its aesthetic problems. Often required to get things.

Therefore, conventionally, when manufacturing a concrete structure, concrete is poured into a mold made into a predetermined shape, and the poured concrete is filled into the mold without any gaps by applying vibration to the mold. At the same time, the air bubbles taken into the concrete by vibration are removed,
It has been attempted to produce a concrete structure that is free from defects and has few surface pores.

Further, in order to produce a concrete structure having fewer surface pores, a sheet-like object is attached to the inner surface of the form, and the gap between the fibers of the sheet-like object is used to insert the concrete into the concrete. A method of letting the taken air bubbles escape upward, or affixing a sheet-like object on the inner surface of the mold, forming a large number of small perforations in the mold, and affixing excess water or air bubbles in concrete The method of letting the perforations formed in the mold through the above-mentioned object escape to the outside has been proposed and partially put into practical use.

Further, in recent years, for the purpose of obtaining a product having good surface properties in a lightweight cellular concrete plate, a cement type quick-setting admixture slurry is applied to the surface of a molding die, and before the slurry is hardened, the weight is reduced. There has been proposed a method for producing a lightweight cellular concrete plate in which a cement slurry of cellular concrete is cast and hardened to form a smooth and dense skin layer on the surface portion (JP-A-2-1).
94904).

[0006]

However, here,
First, in the method of manufacturing a concrete structure that is free from defects and has few surface pores by applying the above-mentioned vibration, the work load is imposed on the worker, and the deafness and white wax of the worker are also caused. In addition, there is a problem that the aggregate in the concrete and the mortar are separated by the vibration, and the concrete structure having a uniform strength cannot be manufactured.

Further, in the method of sticking a sheet-like object to the inner surface of the mold, it takes time and effort to stick the sheet-like object, and the sheet-like object after use and the perforations formed in the mold are used. This method was problematic in terms of workability and economy because it cannot be reused unless it is sufficiently washed.

Further, when the method of forming a smooth and dense skin layer on the surface portion of the lightweight cellular concrete plate described in JP-A-2-194904 is adopted as it is for the production of a concrete structure, Although the problems such as the work load on the workers and the workability described above will be solved, the lightweight cellular concrete plate is used as it is as a building material such as an outer wall material or a ceiling material with its surface exposed. In many cases, the skin layer formed on the surface should not be peeled off or damaged thereafter, and if the layer thickness is too large, the lightness characteristic of the lightweight cellular concrete board may be impaired. Therefore, the above materials that form the skin layer are limited, and the cement slurry of lightweight cellular concrete is hardened before the material that forms the skin layer is cured. Hardened molded by the mold, it is necessary, such as reduced adhesion both interfaces, the construction of a large concrete structure that requires a lot of molding time was unsuitable way.

Further, the concrete structure is rarely used in a state of being directly exposed to the eyes even if it is buried or not buried, and it is required to have the surface properties and the adhesion of the skin layer as the above lightweight cellular concrete plate. Therefore, if the above-mentioned technique described in JP-A-2-194904 is directly applied to the method for manufacturing a concrete structure, a skin layer more than necessary is formed. Since there are problems such as limited procedures, a simpler and economical method has been desired.

The present invention has been made in view of the problems of the above-mentioned conventional techniques, and an object thereof is to provide a concrete structure having a good surface quality with few surface pores,
It is to provide a method suitable for manufacturing a concrete structure that can be provided more easily and economically.

[0011]

In order to achieve the above-mentioned object, the present invention provides a powder containing hydraulic powder, a hydraulic paste, or a powder containing hydraulic powder on the inner surface of the mold before placing concrete. A method for producing a concrete structure is characterized in that hydraulic mortar is sprayed or applied, and then concrete is placed in the internal space formed by the mold.

According to the above-described method for producing a concrete structure according to the present invention, the surface of the concrete structure after demolding is sprayed or applied onto the inner surface of the mold before placing the concrete. Since the powder containing the hydraulic powder, the hydraulic paste, or the hydraulic mortar has a hardened surface layer, the surface layer conceals the surface pores of the concrete structure and has a good surface property. It has the function of providing a concrete structure.

Here, the work for obtaining the above-mentioned action is to spray powder containing hydraulic powder, hydraulic paste or hydraulic mortar onto the inner surface of the mold during or after the mold is assembled. Since it only needs to be sprayed with a gun or applied with a brush, there is no need for complicated steps, and the cost is low, and the sprayed or coated powder containing the hydraulic powder, water Even if the hard paste or hydraulic mortar is hardened and the concrete is placed in the inner space of the mold after hardening, the above-mentioned action and effect can be obtained, so that it is not necessary to hurry, and workability is also improved. It will be good.

In the present invention, when powder containing hydraulic powder is sprayed or applied to the inner surface of the mold before concrete is cast, the inner surface of the mold is to be coated with the powder. It is necessary to apply water or a release agent in advance. This is necessary in order to fix the powder containing the hydraulic powder to be sprayed or applied onto the inner surface of the mold.

The powder to be sprayed or applied to the inner surface of the mold is preferably a powder containing 10% by weight or more of hydraulic powder. This is because even if a hydraulic powder, for example, a powder containing less than 10% by weight of cement is sprayed or applied on the inner surface of the mold, it is difficult to obtain a concrete structure having good surface properties. This is because the test revealed that there is. However, if the hydraulic powder is contained in an amount of 10% by weight or more, the other powder materials are powder materials generally used at construction sites such as blast furnace slag, fly ash, limestone powder, silica fume, carbon dioxide. Calcium powder, silica powder, etc. may be used, and no special powder material is required.

If ultrafine particles such as silica fume or a polymer is used as another powder material to be mixed with the hydraulic powder, a dense layer is formed on the surface of the concrete structure to prevent entry of substances from the outside. Therefore, it also has the effect of improving the resistance to deterioration of concrete such as salt damage, neutralization and alkali-aggregate reaction. Further, by using a powder material that is stable over time as another powder material, it is possible to solve the problem of uneven color on the surface of the concrete structure, which is often a problem.

Further, in the above-mentioned present invention, when the hydraulic paste or hydraulic mortar is sprayed or applied to the inner surface of the mold before the concrete is cast, the hydraulic paste or hydraulic mortar is used. Is preferably a paste or mortar containing 10% by weight or more of hydraulic powder in its powder component. This is the same as in the case of spraying or applying powder containing the above-mentioned hydraulic powder, with a paste containing less than 10% by weight of hydraulic powder, or with mortar, a concrete structure with good surface properties can be obtained. This is because the test revealed that it becomes difficult. However, as long as the hydraulic powder is contained in an amount of 10% by weight or more, the other powder material may be the powder material generally used in the construction site, etc., and the thickener, defoaming agent, water reducing agent, etc. A chemical admixture such as an agent and a shrinkage-reducing agent may be used together if necessary.

The viscosity of the hydraulic paste or hydraulic mortar sprayed or applied to the inner surface of the mold is preferably 100 to 20,000 mPa · s. This is because a paste or mortar having a viscosity of less than 100 mPa · s sprays or is applied to the inner surface of the formwork and then runs off, so that a surface layer covering the surface of the concrete structure cannot be formed. On the contrary, with viscous paste or mortar exceeding 20000 mPa · s, it is difficult to spray or apply the paste, and bubbles are generated in the surface layer to be formed, which also produces a concrete structure having good surface properties. This is because it cannot be done.

Further, when the hydraulic mortar is sprayed or applied to the inner surface of the mold, fine aggregate having a particle diameter of 2.5 mm or less may be used as the fine aggregate of the hydraulic mortar. preferable. This is because when the particle diameter of the fine aggregate to be used exceeds 2.5 mm, it is still difficult to spray or apply, and the air at the time of spraying or applying is entrapped, and air bubbles are generated in the surface layer formed. This is because it will end up.

The method of spraying or coating the powder containing the hydraulic powder, the hydraulic paste or the hydraulic mortar is not particularly limited, but the thickness of the spraying or coating is 0.1 to 5 mm. Is preferred. The release agent may be aqueous or oily. Furthermore, the method for producing a concrete structure according to the present invention can be applied to any form such as wood, steel iron, and styrofoam.

[0021]

EXAMPLES The present invention will be described in more detail with reference to the above-mentioned examples of the present invention together with comparative examples.

Formwork Used The conceptual outline of the formwork used is shown in FIG. This formwork has a height of 1000 mm, a length of 2000 mm, and a buttocks 10.
This is a mold for producing an L-shaped retaining wall having a thickness of 00 mm and a thickness of 150 mm.

Concrete used and materials Cement: Ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) Coarse aggregate: Ome crushed sand (FM 6.79) Fine aggregate: Ome crushed sand (FM 2.71) Water: Groundwater High-performance water reducing agent: Mighty 150 (manufactured by Kao Corporation) Thickener: Asano HF (manufactured by Nippon Cement Co., Ltd.) AE agent: Vinsol (manufactured by Yamasou Chemical Co., Ltd.)-Concrete mix ratio The concrete used is a slump 61 cm manufactured from the above materials. High-fluidity concrete (concrete sample No.
1) and slump 8 cm concrete (concrete sample No. 2). Concrete sample No.
Table 1 shows the mixing ratios of concretes 1 and 2.

[0024]

[Table 1]

Example 1 Water or a water-based mold release agent (Kao Co., Ltd., Liner Seven) was applied to the inner surface of the mold for producing the L-shaped retaining wall shown in FIG. Ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) was used as the hard powder, and limestone powder with a Blaine specific surface area of 3500 cm ² / g was used as the non-hydraulic powder. An appropriate amount (0.1-3 mm thickness) was sprayed. After that, the high-fluidity concrete of Sample No. 1 was driven without vibration before the sprayed powder was hardened, and after the high-fluidity concrete was hardened, the number and area of surface pores of the concrete structure obtained by demolding were obtained. And the area ratio was measured. Note that the surface bubble holes are located at the position 200 in FIG.
Two areas of × 200 mm were taken, and bubbles having a diameter of 2 mm or more were copied in this area, and the number, the area and the area ratio of the surface pores were measured from this copy using an image doctor manufactured by Kawasaki Steel Co., Ltd. .

The measurement results are shown in Table 3. In addition, for comparison, hydraulic powder does not exist in the powder to be sprayed (Comparative Example 1-1), and only the aqueous mold release agent is applied to the inner surface of the mold (Comparative Example 1-). 2), and a concrete structure produced in each of the cases in which only the oil-based mold release agent (Mighty manufactured by Sunhit Shokai Co., Ltd.) was applied to the inner surface of the mold (Comparative Example 1-3). Table 3 shows the measured values of the number of surface pores, the area, and the area ratio.

[0027]

[Table 2]

[Table 3]

According to the above-mentioned Example 1, by using a method of spraying a powder containing 10% by weight or more of hydraulic powder on the inner surface of the mold before placing concrete, the high-fluidity concrete is vibration-free. It is found that the generation of surface bubble holes can be reduced when cast in the mold.

-Example 2- On the inner surface of the mold for producing the L-shaped retaining wall shown in FIG. 1, ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) and non-hydraulic powder are used as hydraulic powder. Limestone powder having a Blaine specific surface area of 3500 cm ² / g, tap water as water, Mighty 150 (manufactured by Kao Corporation) as a high-performance water reducing agent, and Asano HF (manufactured by Nippon Cement Co., Ltd.) as a thickener. A paste having the composition shown in Table 4 was kneaded with a 2-liter Hobart mixer for 2 minutes, and sprayed after directly (Example 2-7) or by applying an aqueous mold release agent (Liner Seven manufactured by Kao Corporation). An appropriate amount (0.1 to 3 mm thickness) was applied by spraying with a gun or applying with a brush. Then, before or after the above-mentioned paste is cured (Example 2-
The high-fluidity concrete of Sample No. 1 was placed in 9) without vibration, and the number, area and area ratio of surface pores of the concrete structure obtained by demolding after hardening the high-fluidity concrete were measured. In addition, Table 4 also shows the plastic viscosity of each prepared paste. The plastic viscosity was measured using an outer cylinder rotary viscometer manufactured by Kyowa Kagaku Co., Ltd. Further, the number of surface pores, the area and the area ratio were measured in the same manner as in Example 1.

The measurement results are shown in Table 5. For comparison, one in which hydraulic powder was not present in the powder component of the paste (Comparative Example 2-1), and the viscosity of the paste was 100 m.
The surface pores of the concrete structure produced in each case of less than Pa · s (Comparative Example 2-2) and one in which the viscosity of the paste exceeds 20000 mPa · s (Comparative Example 2-3). The measured values of the number, area and area ratio are also shown in Table 5.

[0031]

[Table 4]

[Table 5]

According to the second embodiment, the viscosity is 100 to 200.
In the range of 00 mPa · s, by a method of spraying or applying a paste containing 10 wt% or more of hydraulic powder in the powder component on the inner surface of the mold before placing concrete, It was revealed that the generation of surface pores can be reduced when high-fluidity concrete is placed in a mold without vibration.

-Example 3- On the inner surface of the mold for producing the L-shaped retaining wall shown in FIG. 1, ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) and non-hydraulic powder are used as hydraulic powder. As limestone powder with a Blaine specific surface area of 3500 cm ² / g, tap water as water, Toyoura standard sand (particle size 0.3 mm or less) and Ome crushed sand A (particle size 2.5 mm or less) as fine aggregate, high performance water reduction Mighty 150 (manufactured by Kao Co., Ltd.) was used as an agent, and Asano HF (manufactured by Nippon Cement Co., Ltd.) was used as a thickener, and kneaded for 2 minutes with a 2 liter Hobart mixer.
The mortar having the composition shown in (1) was directly used (Example 3-
7) Alternatively, a suitable amount (3 to 5 m) can be obtained by applying an aqueous release agent (Liner Seven manufactured by Kao Co., Ltd.) and then spraying with a spray gun or applying with a brush.
m thickness). After that, before curing the mortar,
Alternatively, after hardening (Example 3-9), the high-fluidity concrete of Sample No. 1 is driven without vibration, and the number and area of surface pores of the concrete structure obtained by demolding the high-fluidity concrete after hardening And the area ratio was measured. In addition, Table 6 also shows the plastic viscosity of each prepared mortar. The plastic viscosity was measured using the same viscometer as in Example 2. Further, the number of surface pores, the area and the area ratio were measured in the same manner as in Example 1.

The measurement results are shown in Table 7. For comparison, a powder composition of mortar containing no hydraulic powder (Comparative Example 3-1) had a mortar viscosity of 100 m.
Those having a viscosity of less than Pa · s (Comparative Example 3-2) and a viscosity of mortar exceeding 20,000 mPa · s (Comparative Example 3-).
3) and Ome crushed sand B (particle size 5) as fine aggregate for mortar
Table 7 shows the measured values of the number, area and area ratio of the surface pores of the concrete structure produced in each case (Comparative Example 3-4).

[0035]

[Table 6]

[Table 7]

According to the third embodiment, the viscosity is 100 to 200.
It is in the range of 00 mPa · s, contains 10% by weight or more of hydraulic powder in the powder component, and has a particle size of 2. as fine aggregate.
When high-fluidity concrete is placed in a form without vibration by spraying or applying mortar using fine aggregate of 5 mm or less to the inner surface of the form before placing the concrete It turns out that the generation of surface bubble holes can be reduced.

Example 4-On the inner surface of the mold for producing the L-shaped retaining wall shown in FIG. 1, the above-mentioned Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-
An appropriate amount (0.1 to 3 mm thickness) of the paste having the composition of 2 was sprayed with an aqueous mold release agent (Liner Seven manufactured by Kao Corporation) and then sprayed. Then, the concrete of sample No. 2 was driven in while vibrating before the above-mentioned paste was hardened, and the number, area and area ratio of surface pores of the concrete structure obtained by demolding after hardening the concrete were measured. . The number of surface pores, the area and the area ratio were measured in the same manner as in Example 1. The measurement results are shown in Table 8.

[0038]

[Table 8]

According to Example 4, the hydraulic paste was sprayed on the inner surface of the mold before the concrete was poured, and concrete having a slump of about 8 cm was poured into the mold while vibrating. Even in such a case, it is proved that the generation of surface pores can be reduced.

-Example 5-On the inner surface of the mold for producing the L-shaped retaining wall shown in FIG. 1, ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) and non-hydraulic powder are used as hydraulic powder. Using limestone powder with a Blaine specific surface area of 3500 cm ² / g and silica fume as ultrafine particles, tap water as water, and Mighty 150 (manufactured by Kao Corporation) as a high-performance water-reducing agent, using a 2-liter Hobart mixer for 2 minutes. The paste having the composition shown in Table 9 was kneaded and coated with an aqueous release agent (Liner Seven manufactured by Kao Co., Ltd.), and then sprayed in an appropriate amount (0.1 to 3 mm thickness) with a spray gun.
After that, the high-fluidity concrete of Sample No. 1 was driven without vibration before hardening of the above paste, and the area ratio of surface pores of the concrete structure obtained by demolding after hardening of the high-fluidity concrete was measured. The measurement results are also shown in Table 9. In addition, Table 9 also shows the plastic viscosity of each paste prepared. The plastic viscosity was measured using the same viscometer as in Example 2, and the area ratio of surface pores was measured by the same method as in Example 1.

[0041]

[Table 9]

According to the above-mentioned Example 5, a hydraulic paste containing ultrafine particles such as silica fume is sprayed onto the inner surface of the formwork before the concrete is poured.
It was revealed that the generation of surface pores can be reduced when high-fluidity concrete is placed in a mold without vibration.

-Example 6- On the inner surface of the 10 x 10 x 40 cm mold, the hydraulic paste having the composition of the above-mentioned Example 5-2 was mixed with an aqueous mold release agent (Kao Corporation Liner Seven). After applying, an appropriate amount (0.1 to 3 mm thickness) was applied with a brush. Then, using a concrete structure obtained by driving the high-fluidity concrete of Sample No. 1 without vibration before hardening of the paste, and removing the mold after hardening of the high-fluidity concrete,
An accelerated neutralization test was conducted under the conditions of 20 ° C. and CO ₂ concentration of 10%. The neutralization depth of the concrete was determined by spraying a 1% alcohol solution of phenolphthalein on the fractured surface of the concrete specimen to reach the red colored portion.

Table 10 shows the measurement results. In addition, for comparison, the measured value of the neutralization depth of the concrete structure of the concrete structure produced by coating only the water-based mold release agent on the inner surface of the mold (Comparative Example 6-1) is also shown in Table 10. To do.

[0045]

[Table 10]

From Example 6 above, a hydraulic paste containing ultrafine particles such as silica fume was sprayed onto the inner surface of the formwork before the concrete was cast.
It turns out that the neutralization of concrete structures can be delayed.

[0047]

As described above, according to the method for manufacturing a concrete structure according to the present invention, it is possible to easily and economically provide a concrete structure having a small number of surface pores and good surface properties. There is.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a mold for producing an L-shaped retaining wall.

FIG. 2 is a schematic side view of an L-shaped retaining wall.

Claims (6)

[Claims] 1. A surface of an inner surface of a mold before pouring concrete is coated with water or a mold release agent, and then powder containing hydraulic powder is sprayed or applied, and then the mold is formed. A method for manufacturing a concrete structure, which comprises placing concrete in an internal space. 2. The concrete structure according to claim 1, wherein the powder to be sprayed or applied to the inner surface of the mold is a powder containing 10% by weight or more of hydraulic powder. Manufacturing method. 3. A hydraulic paste or hydraulic mortar is sprayed or applied onto the inner surface of the mold before the concrete is poured, and then the concrete is poured into the inner space of the mold. A method for manufacturing a concrete structure, comprising: 4. The hydraulic paste or hydraulic mortar sprayed or applied to the inner surface of the mold is a paste or mortar containing 10% by weight or more of hydraulic powder in its powder component. The method for manufacturing a concrete structure according to claim 3, which is characterized in that. 5. The viscosity of the hydraulic paste or hydraulic mortar sprayed or applied on the inner surface of the mold is
It is 100-20000 mPa * s, The manufacturing method of the concrete structure of Claim 3 or 4 characterized by the above-mentioned. 6. The hydraulic mortar sprayed or applied to the inner surface of the mold is a mortar using fine aggregate having a particle diameter of 2.5 mm or less as the fine aggregate. The method for manufacturing a concrete structure according to claim 3, 4 or 5.