JP7285054B2 - Method for producing fluidized concrete and method for constructing concrete structure - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law Announced on April 9, 2018 on the website of Taisei Corporation (http://www.taisei.co.jp/about_us/release/2018/1439263464268.html).

The present invention relates to a method for producing a fluidized concrete in which a fluidizing agent is added to pre-mixed relatively hard concrete (base concrete) to increase fluidity, and a concrete using this fluidized concrete. It relates to a construction method of a structure.

Conventionally, in order to avoid inadequate filling of concrete in walls and column bases with high-density reinforcement, concrete with higher fluidity than ordinary concrete may be used (Patent Document 1- 3).
Patent Literature 1 discloses a method of producing high-fluidity concrete by charging a high-fluidity concrete paste produced by a paste mixer into a track agitator and rotating the track agitator at high speed.
In Patent Document 2, by adding an admixture having water-reducing and viscosity-increasing properties to base concrete and stirring, concrete with high fluidity is produced without increasing the paste (unit water amount or unit cement amount). A method is shown.
Patent Literature 3 discloses a method for producing high-fluidity concrete. Specifically, in Patent Document 3, a package containing a cement dispersant and an inseparable admixture is crushed in concrete or is opened, and a package is prepared, which is described in JIS A-5308. Put the whole package into the agitator of a mixer or concrete agitator vehicle containing the ready-mixed concrete of No. 2, stir the concrete to crush the package or open the package, and pour the mixture in this package into concrete to prepare a highly fluid concrete with a slump of 21 cm or more (slump flow value of 35 cm) without changing the JIS concrete formulation.
In addition, even if you try to place high-fluidity concrete in a formwork with a complicated shape or a formwork with high-density reinforcing bars, high-fluidity concrete is classified as a special type of concrete. In some cases, a concrete manufacturing plant capable of supplying fluid concrete was far from the site, and high fluid concrete could not be used. In addition, in order to use high-fluidity concrete on-site, it is necessary to obtain ministerial approval based on the Building Standards Act, even if it is a small amount of concrete. In practice, it was sometimes difficult to adopt high flow concrete.

JP-A-6-270134 JP 2012-200947 A JP-A-8-52730

The present invention provides a method for producing high-quality fluidized concrete that can be used regardless of the locality of the construction site and is easy to adopt at the actual site, and a method for constructing a concrete structure using this fluidized concrete. intended to provide

The present inventors perform a special kneading operation on site by post-adding a powder admixture (powder fluidizing agent, powder thickener) to the base concrete (normal strength concrete) brought to the site. The present invention has been made by paying attention to the fact that high-quality fluidized concrete can be produced even in a small amount.
The method for producing fluidized concrete of the first invention is a method for producing fluidized concrete, comprising a step of carrying base concrete to a site (for example, step S1 described later), and a powdery admixture in the base concrete and a step of producing fluidized concrete by adding (for example, step S2 described later), and the base concrete has a nominal strength value of 27 N / mm ² or more and 42 N / mm ² or less, and a target slump It is a ready-mixed concrete conforming to JIS A5308 with a value in the range of 18 cm or more and 21 cm or less, wherein the admixture comprises a powdery fluidizing agent and a powdery thickening agent, and the fluidizing agent The amount added is 0.15 kg/m ³ or more and 0.75 kg/m ³ or less with respect to the base concrete, and the addition amount of the thickener is 0.5 kg/m ³ or more with respect to the base concrete. It is characterized by being 2.0 kg/m ³ or less.

According to the present invention, since the admixture (fluidizing agent, thickening agent) to be added later to the ready-mixed concrete brought into the site is powdered, it is possible to change the amount of water that affects the concrete strength of the base concrete. can produce fluidized concrete for in-situ casting without Therefore, since the admixture can be post-added to general base concrete at the site to produce fluidized concrete, concrete with high fluidity can be cast regardless of the regional characteristics of the construction site.
In addition, the fluidized concrete of the present invention can obtain a highly fluid concrete without increasing the unit cement amount by adding a powdery admixture to the ready-mixed concrete. is also cheaper.
In addition, since the powdered admixture is added to the base concrete, which does not require ministerial approval, ministerial approval is not required, making it easy to use at actual sites.
Therefore, in the present invention, it is possible to realize a fluidized concrete having improved fluidity while maintaining the strength characteristics of the base concrete brought in on site without impairing the strength of the concrete.

In the method for producing fluidized concrete of the second invention, the thickening agent is a powder obtained by mixing a cellulose compound and a polycarboxylic acid ether compound, and the fluidizing agent and the thickening agent are each Each predetermined amount is stored in alkaline crushed paper that dissolves in concrete, and in the step of adding an admixture to the base concrete, predetermined amounts of the fluidizing agent and the thickening agent are added to the base concrete. After stirring, the fluidized concrete is characterized in that the target slump flow value according to JIS A1150 is in the range of 45 cm or more and 60 cm or less.

Conventionally, when producing fluidized concrete, it was necessary to accurately measure and add a liquid admixture at the site, which required a lot of time and effort.
However, according to the present invention, predetermined amounts of a powdered fluidizing agent and a thickening agent are contained in alkaline crushed paper that dissolves in concrete to form a paper pack, and a predetermined amount of the paper pack is put into the base concrete. to produce fluidized concrete. Therefore, the amount of the admixture can be accurately adjusted only by managing the number of paper packs, so the productivity of concrete construction at the site is improved.
In addition, the powdered admixture does not require special kneading work at the site, and after being put into the base concrete, it is only necessary to stir it in the mixing drum of the agitator vehicle, so fluidized concrete can be produced efficiently. can.

A method for constructing a concrete structure according to a third aspect of the invention is a method for constructing a concrete structure using fluidized concrete, and includes a step of carrying base concrete from a concrete manufacturing factory to a site using an agitator vehicle (for example, steps described later S1), a step of adding a powdered admixture to the base concrete in the drum of the agitator vehicle to produce fluidized concrete (for example, step S2 described later), and applying the fluidized concrete to the concrete structure. A step of placing in a formwork (for example, step S3 described later), and the base concrete has a nominal strength value of 27 N/mm ² or more and 42 N/mm ² or less, and a target slump value of 18. Ready-mixed concrete that conforms to JIS A5308 and has a range of 21 cm or less, wherein the admixture comprises a powdery fluidizing agent and a powdery thickening agent, and the amount of the fluidizing agent added is , 0.15 kg/m ³ or more and 0.75 kg/m ³ or less with respect to the base concrete, and the addition amount of the thickener is 0.5 kg/m ³ or more and 2.0 kg with respect to the base concrete /m ³ or less.

According to this invention, a powdered admixture was added to the base concrete brought to the site to produce a fluidized concrete. Therefore, since the admixture (fluidizer, thickener) to be added later is in the form of powder, a highly fluid concrete can be obtained without changing the amount of water that affects the concrete strength of the base concrete. . In addition, even if this fluidized concrete is poured into a formwork with a complicated shape or a formwork in which reinforcing bars are densely arranged, there will be no defective filling of the concrete, and a concrete structure in which the concrete is densely filled will not occur. can build things.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a method for producing high-quality fluidized concrete that can be used irrespective of the regional characteristics of construction sites and that can be applied even when the amount of concrete placed is small, and this fluidized concrete. A method for constructing a concrete structure using the method can be provided.

1 is a flow chart of a method for constructing a concrete structure using fluidized concrete according to a first embodiment of the present invention; FIG. 5 is a front view of a wall structure as a concrete structure according to a second embodiment of the present invention; It is a front view of a wall structure as a concrete structure according to a third embodiment of the present invention. FIG. 10 is a vertical cross-sectional view of a wall structure as a concrete structure according to fourth and fifth embodiments of the present invention;

The present invention is a method for producing a fluidized concrete for on-site casting obtained by post-adding a powder admixture (powder fluidizing agent, powder thickener) to base concrete (normal strength concrete) carried into the site. (Fig. 1) and a method of constructing a concrete structure using the fluidized concrete (Figs. 2 to 4). Specifically, in the present invention, at the construction site, normal strength concrete, which is a commercially available product, is used as the base concrete, and a powdery admixture is added to the base concrete afterward, so that the target slump flow value is 45 cm to 45 cm. About 60 cm of fluidized concrete is produced and concrete is placed.
In the present invention, the slump flow value of the fluidized concrete was determined to be about 45 cm to 60 cm, taking into consideration both the cost of the chemical to be added and the fluidity improved by this chemical. Then, based on the following test kneading experiment, fluidized concrete mixing plan, fresh concrete test before and after addition, and compressive strength test, the amount of fluidizer added to the base concrete is 0.15 kg / m ³ or more. .75 kg/m ³ or less, and the amount of thickening agent added to the base concrete is 0.5 kg/m ³ or more and 2.0 kg/m ³ or less, the target slump flow value is about 45 cm to 60 cm. It was confirmed that the concrete material characteristics of
BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In the following description of the embodiments, the same components are denoted by the same reference numerals, and the description thereof will be omitted or simplified.
[First embodiment]
FIG. 1 is a flow chart of a procedure for constructing a concrete structure using post-addition medium-fluid concrete as the fluidized concrete according to the first embodiment of the present invention.
In step S1, base concrete is carried to the site from a concrete manufacturing factory by an agitator vehicle.
In step S2, an admixture is added to the base concrete in the mixing drum of the agitator vehicle to produce post-addition medium-flow concrete.
In step S3, the fluidized concrete in the post-addition mold is placed in the formwork of the structure.

First, the materials used for the base concrete will be explained.
Ordinary Portland cement (JIS R 5210), high-early-strength Portland cement (JIS R5210), blast-furnace cement types A and B (JIS R 5211), and fly ash cement types A and B (JIS R 5213) are used.
Aggregate shall be JIS A 5308 Annex A aggregate for ready-mixed concrete. Fine aggregate shall be sand and crushed sand, and coarse aggregate shall be gravel and crushed stone. The maximum size of coarse aggregate shall be 20 mm or 25 mm for gravel and 20 mm for crushed stone.
Mixing water shall conform to the water used for mixing ready-mixed concrete in JIS A 5308 Annex C.
If fly ash or ground granulated blast furnace slag is used as the admixture, it shall comply with JIS A 6201 or JIS A 6206, respectively.
The admixture used for the base concrete shall be an AE agent, AE water reducing agent or high-performance AE water reducing agent, and conform to JISA 6204. However, naphthalene-based and aminosulfonic acid-based admixtures were excluded because their use together with thickeners may lead to a rapid drop in the fluidity of concrete.

Next, the admixture to be added to the base concrete will be explained. This admixture consists of a powdered fluidizing agent and a powdered thickener.
As the fluidizing agent, Leopac G-100 (registered trademark) manufactured by Lion Specialty Chemicals Co., Ltd. and conforming to JIS A 6204 is used.
Leopac G-100 is specifically a powder containing the following (a) and (b). A predetermined amount of these powders is placed in an alkaline crushed paper that dissolves in concrete to form one pack of fluidizing agent.
(a) alkali salt and/or alkaline earth metal salt of a polycarboxylic acid copolymer having a polyalkylene glycol chain (b) non-swelling inorganic powder Ready-mixed concrete with a nominal strength of 0.05% or more and 0.25% or less and a nominal strength of 27 N/mm ² or more and 42 N/mm ² or less, and approximately 0.5 packs/m ³ or more and 2.5 packs/m ³ or less (0.15 kg/m ³ or more and 0.75 kg/m ³ or less).

The thickener is based on Leopak G-100 (registered trademark) and Leopak G-200 (registered trademark) manufactured by Lion Specialty Chemicals Co., Ltd. These Leopak G-100 (registered trademark) and Leopak G-200 (registered trademark), a cellulose compound and a polycarboxylic acid ether compound are mixed in a predetermined ratio so that fluidity can be maintained for a long time by the action of a surfactant that suppresses aggregation of cement particles ( developed thickener).
Specifically, the developed thickener is a powder containing the following (a), (b), and (c). That is, (c) is added to Leopak G-100. A predetermined amount of these powders is placed in an alkaline crushed paper that dissolves in concrete to form one pack of thickener.
(a) Alkali salt and/or alkaline earth metal salt of polycarboxylic acid copolymer having polyalkylene glycol chain (b) Non-swelling inorganic powder (c) Cellulose derivative having hydroxyl group Developed thickener The standard addition amount is 1 pack/m ^{3 or} more and 4 packs/m ^{3 or} less (0.5 kg/m ³ or more and 2.0 kg/m ³ or less).
Table 1 shows the quality standards for superplasticizers and thickeners.

The amount of fluidizing agent to be added is basically determined by trial kneading, and when the slump of the base concrete fluctuates and the target slump flow value of the post-addition type medium-fluid concrete cannot be obtained, the standard amount of addition (0.5 to 3. 0 pack/m ³ ). In addition, as a general rule, the amount of the thickening agent to be added is not changed from that determined by trial kneading.
Here, the case of an agitator truck with a concrete loading capacity of 4.25 m ³ is exemplified. The standard dosage is 4 packs of superplasticizer and 8 packs of thickener per vehicle. As a guideline for adjustment, the slump flow value increases or decreases by about 3 cm to 5 cm by increasing or decreasing one pack of fluidizing agent per unit. A guideline for the amount of excessive addition is 15 packs or more of fluidizing agent per vehicle.

The base concrete and the post-addition type medium-flow concrete are blended so as to obtain the qualities shown in Table 2 below.

The formulation design of the post-addition type medium-flow concrete is determined by trial kneading so that the performance shown in Table 2 above is obtained.
The mixing strength of post-addition medium-flow concrete is determined by the mixing strength of the base concrete. The base concrete is, in principle, a ready-mixed concrete conforming to JIS A5308 having a nominal strength value of 27 N/mm ² or more and 42 N/mm ² or less.
The target slump of the base concrete shall be 18 cm or 21 cm. The target slump flow value for post-addition type medium-fluidity concrete is, in principle, 45 cm or 50 cm. However, the required fluidity and material separation resistance were confirmed by trial kneading for formulations with a relatively large unit cement amount (at least nominal strength of 33 or more) and formulations with corrected fine aggregate ratio and unit coarse aggregate amount. In some cases, it can be 55 cm or 60 cm.
The air content of the base concrete and the post-addition medium-flow concrete is 4.5%.
The water-cement ratio is set as follows according to the target slump flow value. If the target slump flow value is 45 to 50 cm, the water-cement ratio should be 55% or less. If the target slump flow value is 55 cm, the water-cement ratio should be 50% or less. % or less.

The unit water volume shall be 175 kg/m ³ or less.
In principle, the unit cement amount should be 300 kg/m ³ or more. However, when the required fluidity and material separation resistance are confirmed by trial kneading, the amount can be 280 kg/m ³ or more.
The unit amount of coarse aggregate shall be 500 L/m ³ or more in bulk volume, and when the target slump flow value is 55 to 60 cm, the bulk volume shall be 340 L/m ³ or less in absolute volume.
The amount of AE water reducing agent or high-performance AE water reducing agent used in the base concrete is determined so as to obtain the predetermined slump and air content of the base concrete.
The amount of the post-addition type medium-flow concrete admixture to be added is determined so as to obtain a predetermined slump flow value for the post-addition type medium-flow concrete.
An example of a standard design formulation for post-addition medium-flow concrete is shown in Table 3 below.

By trial kneading, a fresh concrete test and a compressive strength test are performed before and after the addition of the post-addition type medium-flow concrete admixture, and it is confirmed that the required performance is obtained. In addition, although trial kneading is basically performed using an actual machine, in the case of indoor trial kneading, the standard amount of kneading per batch is 30 L, and the amount of fluidizing agent added is adjusted to 1.76 g/30 L (235 g per pack). / ^4m3 equivalent) unit. The amount of thickener to be added is basically 1000 g/m ³ , and if adjustment is required, it is adjusted in units of 3.75 g/30 L (equivalent to 500 g/4 m ³ per pack).
Table 4 shows the test items and judgment criteria for base concrete and post-addition medium-flow concrete. If the ready-mixed concrete factory to be used has a sufficient track record or reliable data, the compressive strength test of the base concrete can be omitted.

In the above test items, if each of the criteria in Table 4 is met, it is judged as passing. If any of the test items is out of the allowable range in this test, a new sample is collected and the same test is performed only once.
If the base concrete or post-addition medium-flowing concrete does not satisfy the criteria, refer to the items (α) to (γ) below to change the formulation, and if necessary, perform trial kneading again.
(α) If the predetermined slump is not obtained for the base concrete, the amount of admixture added is adjusted.
(β) If a predetermined slump flow value cannot be obtained for the post-addition type medium-fluid concrete, the amount of the fluidizing agent to be added is adjusted.
(γ) Although the prescribed slump flow value was obtained for the post-addition type medium-fluid concrete, if separation is visually observed, adjust the fine aggregate ratio to reduce the unit coarse aggregate amount, or reduce the unit cement amount. increase (reduce the water-cement ratio). If it still does not improve, increase the amount of thickener added.

The post-addition type medium-fluidity concrete is produced at the construction site according to the following procedures (I) to (IV).
(I) Stir the base concrete, check the state of the fresh concrete, and determine the amount of fluidizing agent to be added. The fluidizing agent and the thickening agent are measured by the number of bags in the pack, and are not used in units of less than one pack.
(II) A predetermined number of packs of the thickening agent and the fluidizing agent are successively charged into the mixing drum containing the base concrete of the agitator wheel. It is desirable to throw the packs as deep into the drum as possible in a safe and comfortable posture.
(III) Immediately after adding the post-addition type medium-fluidity concrete admixture, high-speed stirring is performed for 2 minutes or longer.
(IV) If the amount of fluidizing agent to be added according to planned preparation does not provide the desired fluidity, the amount of fluidizing agent to be added is adjusted within the range of the standard amount to be added. At this time, the adjustment amount of the fluidizing agent is determined based on the fact that the slump flow value increases or decreases by about 3 cm to 5 cm per pack of 4 m ³ of fresh concrete.

According to this embodiment, there are the following effects.
(1) Since the admixtures (fluidizers and thickeners) to be added to the ready-mixed concrete delivered to the site are powdered, the water content of the base concrete, which affects the strength of the base concrete, does not change. Can produce fluidized concrete for casting. Therefore, even at local construction sites, fluidized concrete can be produced by adding an admixture to general base concrete at the site, so concrete with high fluidity can be produced regardless of the regional characteristics of the construction site. can be cast.
In addition, by adding powdery admixture to ready-mixed concrete, it is possible to obtain post-additive medium-fluidity concrete with high fluidity without increasing the amount of unit cement, making it cheaper than conventional high-fluidity concrete. Become.
In addition, since the powdered admixture is added to the base concrete, which does not require ministerial approval, ministerial approval is not required, making it easy to use at actual sites.
Therefore, it is possible to realize a fluidized concrete with improved fluidity while maintaining the strength characteristics of the base concrete brought in on site without impairing the strength of the concrete.

(2) Alkaline pulverized paper that dissolves in concrete contains predetermined amounts of a powdery fluidizing agent and a thickening agent to form a paper pack, and a predetermined amount of the paper pack is put into the base concrete, A post-addition medium-flow concrete is produced. Therefore, the amount of the admixture can be accurately adjusted only by managing the number of paper packs, so the productivity of concrete construction at the site is improved.
In addition, the powdered admixture does not require any special kneading work at the site. It can be manufactured efficiently.

(3) Even when the post-addition type medium-fluid concrete was placed in a formwork with a complicated shape or a formwork in which reinforcing bars were densely arranged, the concrete was densely filled without defective filling of the concrete. Can build concrete structures.

[Second embodiment]
FIG. 2 is a front view of a wall structure 1A as a concrete structure according to the second embodiment of the present invention.
In the wall structure 1A, a new wall opening 13 is constructed by constructing a post-cast frame 12 using post-addition medium-fluidity concrete in a wall opening 11 of an existing wall 10 constructed using ordinary concrete. It is. Specifically, the existing wall 10 is surrounded by columns 14 and beams 15 and is constructed using ordinary concrete. First, a wall reinforcement (not shown) is newly arranged inside the wall opening 11 of the existing wall 10 . The wall reinforcement includes the opening reinforcing reinforcement 16, and has a high-density reinforcement arrangement. Next, a formwork (not shown) is erected, and the post-addition type medium-fluid concrete of the first embodiment is poured into this formwork to construct the post-cast building body 12 . In this embodiment, the wall structure 1A is constructed by constructing the post-strengthened frame 12 on the existing wall 10, but the present invention is not limited to this, and the entire wall structure 1A may be newly constructed.
According to this embodiment, in addition to the effects (1) and (2) described above, the following effects are obtained.

(4) By using post-addition type medium-fluidity concrete with high fluidity, even in areas where bars are densely arranged, there is no defective concrete filling, and post-casting with densely filled concrete can be achieved. A skeleton 12 can be constructed.

[Third Embodiment]
FIG. 3 is a front view of a wall structure 1B as a concrete structure according to a third embodiment of the present invention.
In the wall structure 1B, a wall 22 having three wall openings 21 is constructed by post-strapping an existing frame 20 . Specifically, the existing frame 20 is composed of columns 23 and beams 24 constructed using ordinary concrete. First, wall reinforcement (not shown) is newly arranged in the existing frame 20, then a formwork (not shown) is erected, and ordinary concrete and post-addition type medium-flow concrete of the first embodiment are poured into this formwork. Concretely, a wall 22 for post-casting is constructed. Here, since a sufficient space is secured between the wall opening 21 and the beam 24, base concrete, which is ordinary concrete, is placed. On the other hand, since a sufficient space is not secured between the wall openings 21 and between the wall openings 21 and the pillars 23, a vibrating vibrator is inserted into the concrete cast in the formwork to It is difficult to apply vibration to Therefore, the post-addition medium-fluid concrete of the first embodiment is placed between the wall openings 21 and between the wall openings 21 and the pillars 23 . In this embodiment, the wall structure 1B is constructed by constructing the wall 22 on the existing skeleton 20 by post-strapping, but the construction is not limited to this, and the entire wall structure 1B may be newly constructed.
According to this embodiment, in addition to the effects (1) and (2) described above, the following effects are obtained.

(5) Even in areas where sufficient gaps cannot be secured, by using post-addition medium-fluid concrete with high fluidity, the walls are filled with concrete densely without causing defective concrete filling. 22 can be constructed.
In addition, since an admixture (fluidizer, thickener) is added to the base concrete at the site to produce post-addition type medium-fluid concrete with high fluidity, like the post-cast wall 22, some It is easy to separate the concrete by pouring the base concrete and pouring the remaining medium-flow concrete after addition.

[Fourth Embodiment]
FIG. 4(a) is a longitudinal sectional view of a wall structure 1C as a concrete structure according to a fourth embodiment of the present invention.
In the wall structure 1C, an additional wall 31 having a thin wall thickness is constructed by post-strapping an existing wall 30 . Specifically, the existing wall 30 is surrounded by columns and beams 32 (not shown) and is constructed using ordinary concrete. On the surface of the existing wall 3, wall reinforcement (not shown) is newly arranged. Next, a formwork (not shown) is erected, and the post-addition type medium-fluid concrete of the first embodiment is poured into this formwork to construct the post-strike additional wall 31 .
According to this embodiment, in addition to the effects (1) and (2) described above, the following effects are obtained.

(6) Even if the wall thickness of the additional concrete wall 31 is thin, by using post-addition type medium-fluid concrete with high fluidity, the additional concrete wall 31 is densely filled with concrete without causing defective concrete filling. can be constructed.

[Fifth Embodiment]
FIG. 4(b) is a longitudinal sectional view of a wall structure 1D as a concrete structure according to the fifth embodiment of the present invention.
The wall structure 1D is constructed by constructing a wall 41 on an existing frame 40 by post-casting, for example, in a basement floor employing a reverse-casting method. Specifically, the existing frame 40 is composed of columns and beams 42 (not shown) constructed using ordinary concrete. First, wall reinforcement (not shown) is newly arranged in the existing frame 20, then a formwork (not shown) is erected, and base concrete, which is ordinary concrete, is poured into this formwork. At this time, a gap is formed between the upper end surface of the placed ordinary concrete and the upper beam 42, and the post-addition medium-fluid concrete of the first embodiment is placed in this gap.
According to this embodiment, in addition to the effects (1) and (2) described above, the following effects are obtained.

(7) Even in areas where sufficient gaps cannot be secured, by using post-addition type medium-fluid concrete with high fluidity, a post-cast wall in which concrete is densely filled without causing poor concrete filling. 41 can be constructed.
In addition, since an admixture (fluidizer, thickener) is added to the base concrete at the site to produce post-addition type medium-fluid concrete with high fluidity, most of the material such as the post-cast wall 41 is It is easy to separate the concrete by pouring the base concrete and pouring the remaining medium-flow concrete after addition.

It should be noted that the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.
For example, in the above-described second to fifth embodiments, each wall structure has a portion constructed with normal-strength concrete and a portion constructed with post-addition type medium-fluidity concrete with complex shapes and densely arranged reinforcing bars. However, the wall structure is not limited to this, and the entire wall structure may be constructed of post-addition type medium-fluid concrete.
In addition, in the above-described second to fifth embodiments, the wall structure was constructed using the post-addition type medium-fluidity concrete of the present invention. Concrete structures with complicated shapes, corners of box culverts where reinforcing bars are arranged at high density, column-to-beam joints of buildings, and the like may be constructed.

1A to 1D ... wall structure (concrete structure)
DESCRIPTION OF SYMBOLS 10... Existing wall 11... Wall opening 12... Post-strike frame 13... Wall opening 14... Column 15... Beam 16... Opening reinforcing bar 20... Existing frame 21... Wall opening 22... Post-strike wall 23... Column 24 ...Beam 30...Existing wall 31...Additional wall 32...Beam 40...Existing framework 41...Post-strike wall 42...Beam

Claims (2)

A method for producing fluidized concrete in which an admixture is added to pre-mixed base concrete at the construction site to increase the fluidity suitable for the construction site, comprising:
a step of carrying the base concrete to the site;
adding a powdered admixture to the base concrete to produce a fluidized concrete;
The base concrete is a ready-mixed concrete conforming to JIS A5308 having a nominal strength value of 27 N/mm ² or more and 42 N/mm ² or less and a target slump value of 18 cm or more and 21 cm or less,
The admixture comprises a powdery fluidizing agent and a powdery thickening agent,
The amount of the fluidizing agent to be added is 0.15 kg/m ³ or more and 0.75 kg/m ³ or less with respect to the base concrete,
The amount of the thickening agent to be added is 0.5 kg/m ³ or more and 2.0 kg/m ³ or less with respect to the base concrete,
The fluidizing agent is an agent containing (a) an alkali salt and/or an alkaline earth metal salt of a polycarboxylic acid copolymer having a polyalkylene glycol chain and (b) a non-swelling inorganic powder,
The thickener comprises (a) an alkali salt and/or an alkaline earth metal salt of a polycarboxylic acid copolymer having a polyalkylene glycol chain, (b) a non-swelling inorganic powder, and (c) a hydroxyl group. It is a powder mixed with a cellulose derivative , and the viscosity of the thickener is 750 mPa · S or more and 1250 mPa · S or less,
Each of the fluidizing agent and the thickening agent is housed in alkaline crushed paper that dissolves in concrete in predetermined amounts,
In the step of producing the fluidized concrete, after adding a predetermined amount of the fluidizing agent and the thickening agent to the base concrete, the mixture is stirred and trial kneaded, and the slump flow and air content of the trial kneaded fluidized concrete are , and compressive strength, and if the determination is negative, adjust the input amount of at least one of the plasticizer and the thickener and try again Kneading is performed, and when the determination is affirmative, the formulation design of the fluidized concrete is determined with the respective amounts of the fluidizing agent and the thickening agent, and the slump flow value according to the provisions of JIS A1150. A method for producing fluidized concrete, characterized in that the fluidized concrete is produced in a range of 45 cm or more and 60 cm or less. A method for constructing a concrete structure using fluidized concrete obtained by adding a fluidizing agent to pre-mixed base concrete at the construction site to increase the fluidity suitable for the construction site,
A process of carrying base concrete from a concrete manufacturing factory to the site by an agitator vehicle;
adding a powdered admixture to the base concrete in the drum of the agitator vehicle to produce a fluidized concrete;
placing the fluidized concrete in the formwork of the structure;
The base concrete is a ready-mixed concrete conforming to JIS A5308 having a nominal strength value of 27 N/mm ² or more and 42 N/mm ² or less and a target slump value of 18 or more and 21 cm or less,
The admixture comprises a powdery fluidizing agent and a powdery thickening agent,
The amount of the fluidizing agent to be added is 0.15 kg/m ³ or more and 0.75 kg/m ³ or less with respect to the base concrete,
The amount of the thickening agent to be added is 0.5 kg/m ³ or more and 2.0 kg/m ³ or less with respect to the base concrete,
The fluidizing agent is an agent containing (a) an alkali salt and/or an alkaline earth metal salt of a polycarboxylic acid copolymer having a polyalkylene glycol chain and (b) a non-swelling inorganic powder,
The thickener comprises (a) an alkali salt and/or an alkaline earth metal salt of a polycarboxylic acid copolymer having a polyalkylene glycol chain, (b) a non-swelling inorganic powder, and (c) a hydroxyl group. It is a powder mixed with a cellulose derivative , and the viscosity of the thickener is 750 mPa · S or more and 1250 mPa · S or less,
Each of the fluidizing agent and the thickening agent is housed in alkaline crushed paper that dissolves in concrete in predetermined amounts,
In the step of producing the fluidized concrete, after adding a predetermined amount of the fluidizing agent and the thickening agent to the base concrete, the mixture is stirred and trial kneaded, and the slump flow and air content of the trial kneaded fluidized concrete are , and compressive strength, and if the determination is negative, adjust the input amount of at least one of the plasticizer and the thickener and try again Kneading is performed, and when the determination is affirmative, the formulation design of the fluidized concrete is determined with the respective amounts of the fluidizing agent and the thickening agent, and the slump flow value according to the provisions of JIS A1150. A method for constructing a concrete structure, characterized by producing fluidized concrete having a diameter in the range of 45 cm or more and 60 cm or less.

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