JPH11131802A - Lightweight concrete and concrete compacts - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Conventionally, there has been no concrete that is lightweight and has a high elastic modulus. Therefore, the present invention provides a lightweight concrete having good workability, excellent appearance, high strength, and high elastic modulus, and a molded concrete obtained by casting the ready-mixed concrete into a formwork. It is what we are trying to get. SOLUTION: A non-lightweight aggregate having a specific gravity of less than 1.0, an inorganic powder such as stone powder, cement, a water reducing agent and water are kneaded to prepare a ready-mixed concrete, which is cured to obtain a lightweight concrete. . The ready-mixed concrete was cast into a mold having a desired shape, and was cured to obtain a molded body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lightweight concrete and concrete moldings. More specifically, the present invention relates to a lightweight concrete and a concrete molded body that are lightweight, have good workability, are excellent in appearance, and have high elastic modulus and strength.

[0002]

2. Description of the Related Art Conventionally, there has been no lightweight concrete having a high elastic modulus. Class I concrete using artificial lightweight coarse aggregate as coarse aggregate and river sand as fine aggregate has higher elastic modulus but higher specific gravity than concrete using artificial lightweight aggregate for both fine and coarse aggregate. . The lighter the concrete, the easier it is to handle, but the lower the modulus of elasticity. In addition, the lower the elastic coefficient, the more easily it bends. For this reason, concrete that is light and has a high elastic modulus is required. For example,
The specific gravity is lighter than that of Class I concrete, preferably both the fine and coarse aggregates are the same or lighter than the concrete using artificial lightweight aggregate, and the elastic modulus is the same or higher than that of Class I concrete. ing.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and both the fine and coarse aggregates are as light as or lighter than concrete using artificial lightweight aggregate. And the elastic modulus is
It is an object of the present invention to provide a lightweight concrete and a concrete molded body that are equal to or more than the seed concrete.

[0004]

That is, the present invention relates to a light-weight aggregate obtained by blending a light-weight aggregate, an inorganic powder, a cement, a water-reducing agent and water which are dried in a completely dry state or at a water absorption rate of 50% or less. It provides concrete. Further, the present invention provides the above lightweight concrete, wherein the specific gravity of the lightweight aggregate in an absolutely dry state is less than 1.0. Further, the present invention provides the above lightweight concrete, wherein the inorganic powder is natural stone powder and / or ceramic powder. Furthermore, the present invention provides that the inorganic powder has an aggregate volume of 1%.
The present invention provides the above lightweight concrete used at 0% or less. The present invention also provides the above lightweight concrete, which is prepared with a water cement ratio of 60% or less. Furthermore, the present invention provides a completely dry state or a water absorption rate of 5.
A lightweight concrete, a mineral powder, a cement, a water reducing agent and water, which are dried at a ratio of 0% or less, are blended to prepare a ready-mixed concrete, and the ready-mixed concrete is cast into a form having a desired shape. It is intended to provide a lightweight concrete molded product obtained by curing.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Conventional lightweight concrete has a low modulus of elasticity and is therefore easily deformed, so that its usable fields are limited. Therefore, concrete is usually used in the end. Generally, concrete is heavy, and handling of the molded product has not been easy from the viewpoint of workability. This was common sense in the prior art.
However, lightweight concrete, which is dried in a completely dry state or at a water absorption rate of 50% or less, and further contains inorganic powder, and preferably has a water cement ratio of 60% or less, has a low specific gravity. It has a high elastic modulus and good strength. Furthermore, if the ready-mixed concrete is cast into a mold having a desired shape, it can be formed into any shape such as a plate shape. The obtained lightweight concrete of the present invention has the same appearance as ordinary concrete and has excellent durability, so that it can be used as so-called exposed concrete.

[0006] The cement used for the lightweight concrete of the present invention is not particularly limited. For example, alumina cement, ordinary Portland cement, early-strength Portland cement, belite cement, ternary cement, or the like can be used. The water reducing agent used in the lightweight concrete of the present invention is not particularly limited. For example, a polycarboxylic acid-based water reducing agent is also suitably used. Specific examples of the polycarboxylic acid-based water reducing agent include a composite (calcium-based) whose main component is a polycarboxylic acid ether. Commercially available products can also be suitably used, and examples thereof include SP-8HE (trade name, manufactured by NMB Corporation) and Mighty 2000TH (trade name, manufactured by Kao Corporation). Other water reducing agents can also be used. In addition, an AE agent and an antifoaming agent can be used together with a water reducing agent. The AE agent and defoamer used in the lightweight concrete of the present invention are not particularly limited. Examples of the AE agent include 775S (trade name, manufactured by NMB), 404 (trade name, manufactured by NMB) as an antifoaming agent, and AFK-2 (trade name, manufactured by Takemoto Yushi Co., Ltd.). Other AE agents and defoamers can also be used. The mixing ratio of the water reducing agent in the present invention varies depending on the type of water reducing agent to be used, the type of cement to be used, and the water-cement ratio. For example, 1.2 to 6.0 liter / m ³ , preferably 3 . 0 to 5.0 l / m ³
Is good.

As the inorganic powder used in the present invention, for example, natural stone powder and ceramic powder are preferred. In addition, crushed insulators can also be used. These can be used in combination. Commercially available ones can also be used, and examples thereof include Kibinishi powder manufactured by Natsume Crushed Stone Co., Ltd., and Caltac-H manufactured by Sumitomo Osaka Cement Co., Ltd. The particle size of these inorganic powders is, for example, 0.01 to 2.0.
mm, preferably 0.1 to 1.2 mm.

[0008] The lightweight aggregate used in the lightweight concrete of the present invention is in a completely dry state or at a water absorption of 50% or less at the time of mixing. Both the coarse aggregate and the fine aggregate in the lightweight aggregate are not limited, and various types can be selected according to the purpose. For example, a natural lightweight aggregate from Oshima and an artificial lightweight aggregate can be used in combination. As specific examples of the artificial lightweight aggregate, G-lite (trade name, manufactured by Sunlight Co., Ltd.) can be used as fine aggregate, and Super Mesalite (trade name, manufactured by Nippon Mesalite Industry Co., Ltd.) can be used as coarse aggregate. . Other artificial lightweight coarse aggregates and artificial lightweight fine aggregates can also be used. The mixing ratio of such a lightweight aggregate can be appropriately determined depending on the purpose of use. The lightweight aggregate used in the lightweight concrete of the present invention does not need to be wet, and can be used in a completely dry state. However, if necessary, the lightweight aggregate can be wetted, and can be used even in a water-absorbed state of up to about half the water absorption of the lightweight aggregate. In the lightweight aggregate used in the lightweight concrete of the present invention, it is desirable that the coarse aggregate or the fine aggregate has a specific gravity of less than 1.0 in a completely dry state. The water-cement ratio of the lightweight concrete of the present invention is preferably 60% or less, and is usually in the range of 20 to 60%. More preferably, the water cement ratio is 55% or less. The lightweight concrete of the present invention can be kneaded after charging materials into a mixer, and can be mixed with a water mixture and a water reducing agent, and can be subjected to main mixing, as in the case of conventional lightweight concrete. Can be cast by means of Further, other admixture materials can be blended as needed.

[0009] Curing of the lightweight concrete of the present invention can employ the same means as for conventional concrete.
For example, steam curing can also be adopted, so that adverse effects such as cracks do not occur.

[0010]

The present invention will be further described below with reference to examples and comparative examples. (Example 1) Lightweight concrete of the present invention was prepared in accordance with the mixing ratio shown in Table 1 below. In Table 1, the artificial lightweight fine aggregate and the artificial lightweight coarse aggregate are manufactured by Sunlight Co., Ltd., trade name: G light, and the water reducing agent is a polycarboxylic acid-based water reducing agent; Product name SP-8H
E. The absolute specific gravity of G light is less than 1.0. As the inorganic powder, limestone powder manufactured by Sumitomo Osaka Cement Co., Ltd. under the trade name Caltac-H was used. The maximum particle size of the limestone powder is 0.6 mm and the specific gravity is 2.71.

[0011]

[Table 1]

According to the above mixing ratio, each material was put into a mixer and then kneaded. Then, a preparation water and a water reducing agent were charged and main kneading was carried out. The workability of ready-mixed concrete was sufficient. Slump value was 16 cm. Although a plate-shaped member having a thickness of 4 cm was made and seen, its manufacture was not difficult. Pour the above ready-mixed concrete into the prescribed formwork, φ10 × 20c
A specimen having a size of m was obtained, and its compressive strength and specific gravity were measured. Table 2 shows the results.

[0013]

[Table 2]

[Elastic Modulus Measurement Results] At the time of measuring the compressive strength in Table 2, the elastic modulus was also measured. The measurement result is 10 × 10 ⁴
(N / mm ² ).

Example 2 A lightweight concrete of the present invention was prepared according to the mixing ratio shown in Table 3 below. In Table 3, the artificial lightweight fine aggregate was manufactured by Sunlight Co., Ltd., and the product name was G-lite. The artificial lightweight coarse aggregate was manufactured by Nippon Mesalite Industry Co., Ltd., the product name was Super Mesalite, and the water reducing agent was polycarbon. It is an acid-based water reducing agent, and is a product name “Mighty 2000TH” manufactured by Kao Corporation. The absolute dry specific gravity of G-lite and Super Mesalite is less than 1.0. As the inorganic powder, a guest stone powder manufactured by Natsume Crushed Stone Co., Ltd. was used. The maximum particle size of the guest's stone is 1.2 mm and the specific gravity is 2.6.

[0016]

[Table 3]

According to the above mixing ratio, each material was put into a mixer and then kneaded. Then, a preparation water and a water reducing agent were charged and main kneading was carried out. The workability of the concrete was sufficient. Slump value was 20 cm. A plate member with a thickness of 4 cm and a width of 15 cm and a flat plate with a reinforcing bar of 2 m × 3 m were manufactured, and the manufacture was not difficult. The ready-mixed concrete was cast into a prescribed formwork to obtain a specimen having a size of φ10 × 20 cm, and its compressive strength and specific gravity were measured. Table 4 shows the results.

[0018]

[Table 4]

Comparative Example 1 A conventional lightweight concrete was prepared according to the mixing ratio shown in Table 5 below. In Table 5, the artificial lightweight fine aggregate and the artificial lightweight coarse aggregate are Mesalite (trade name, manufactured by Nippon Mesalight Industry Co., Ltd.), and both are used in a surface-dry state (the water absorption of the aggregate is 50% or more). Was.
The water reducing agent is a polycarboxylic acid-based water reducing agent, and has a trade name of SP-8HE manufactured by NMB Corporation.

[0020]

[Table 5]

According to the above mixing ratios, each material was put into a mixer and then kneaded. Then, a preparation water and a water reducing agent were charged and main kneading was carried out. The workability of ready-mixed concrete was sufficient. Slump value was 18 cm. The ready-mixed concrete was cast into a prescribed formwork to obtain a specimen having a size of φ10 × 20 cm, and its compressive strength and specific gravity were measured. Table 6 shows the results.

[0022]

[Table 6]

[Results of Measurement of Elastic Modulus] At the time of measuring the compressive strength in Tables 3 and 5, the elastic modulus was also measured. The measurement results were both 1.4 × 10 ⁴ (N / mm ² ). In addition, when the inorganic powder is not used for the concrete of Table 3, the elastic coefficient is 0.8 × 10 ⁴ (N / mm ² ), and when the inorganic powder is used, the specific gravity is about 1.2 (Table 4) and the specific gravity is 1 .7 has the same elastic modulus as the concrete of Table 5 and the effect of the present invention is recognized here.

Example 3 A lightweight concrete of the present invention was prepared according to the mixing ratio shown in Table 7 below. Table 5 shows the mixing ratio.
Is almost the same as In Table 7, the artificial lightweight fine aggregate and the artificial lightweight coarse aggregate are Mesalite (trade name) manufactured by Nippon Mesalite Industry Co., Ltd., and both were used in a completely dry state. The water reducing agent is a polycarboxylic acid-based water reducing agent, and has a trade name of Mighty 2000TH manufactured by Kao Corporation.

[0025]

[Table 7]

According to the mixing ratios shown in Table 7 above, each material was charged into a mixer and then kneaded. Then, the prepared water and a water reducing agent were charged and the main kneading was performed. The workability of the concrete was sufficient. Slump value was 16 cm. 4cm thick
A plate member having a width of 15 cm and a width of 2 cm × 3 m with a reinforcing bar was produced, and the production was not difficult. The ready-mixed concrete was cast into a prescribed formwork to obtain a specimen having a size of φ10 × 20 cm, and its compressive strength and specific gravity were measured. Table 8 shows the results.

[0027]

[Table 8]

[Elastic Modulus Measurement Results] At the time of measuring the compressive strength in Table 7, the elastic modulus was also measured. The measurement result is 1.9 × 10 ⁴
(N / mm ² ).

(Example 4: Workability and Fillability) A 30 cm square height 2 of the ready-mixed concrete shown in Table 1, Table 3, Table 5, and Table 7
m columns were constructed. The concrete in Table 5 is a conventional artificial lightweight concrete. At 56 days of age, each pillar was core-bowled, and the distribution of coarse aggregate in the upper, middle, and lower portions of the pillar was examined. It was found that the distribution of coarse aggregate in the upper, middle, and lower portions of each pillar had little variation. The workability and fillability of each concrete were almost the same level.

(Example 5: Steam Curing) 2 m × 2 m with a height of 20 cm of the ready-mixed concrete shown in Tables 1, 3, 5 and 7
Was manufactured at 50 ° C. for 3 hours. The concrete in Table 5 is a conventional artificial lightweight concrete. Each PC plate was released from the mold 16 hours after casting, but had no problem. No cracking occurred. Finishing workability was almost the same.

(Example 6) A 1m x 1m unstrengthened block slab having a height of 5cm was manufactured from the ready-mixed concrete shown in Tables 1, 3, 5 and 7, and steam-cured at 40 ° C for 2 hours. . Table 5
Concrete is conventional artificial lightweight concrete.
Each block was released 18 hours after casting, but had no problems. No cracking occurred. Finishing workability was almost the same.

[0032]

The lightweight concrete or concrete compact of the present invention is obtained by blending a lightweight aggregate, an inorganic powder, a cement, a water reducing agent and water which are dried in a completely dry state or at a water absorption rate of 50% or less. Therefore, it has a high elastic modulus not found in conventional lightweight concrete, is lightweight, has good workability, has excellent appearance, and has high strength. The lightweight concrete of the present invention can be
Since any casting method can be applied, the present invention can be applied to structures having any shape and form such as a reinforced concrete structure, a steel frame structure, and a wooden structure. In addition, the lightweight concrete of the present invention has the same finishability as conventional lightweight concrete, so that it maintains a high elasticity coefficient, is excellent in appearance, and can be used as an outer wall material, an inner wall material and the like. Further, it can also be used as an outer wall member or an inner wall member constituting a part of the outer wall material and the inner wall material, a floor material, a roof material and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 103: 30 111: 40

Claims (6)

[Claims] 1. A lightweight concrete obtained by mixing a lightweight aggregate, an inorganic powder, a cement, a water reducing agent and water which are dried in a completely dry state or at a water absorption rate of 50% or less. 2. The lightweight concrete according to claim 1, wherein the specific gravity of the lightweight aggregate in an absolutely dry state is less than 1.0. 3. The lightweight concrete according to claim 1, wherein the inorganic powder is a natural stone powder and / or a ceramic powder. 4. The lightweight concrete according to claim 1, wherein the inorganic powder is used in an amount of 10% or less of the volume of the aggregate. 5. The lightweight concrete according to claim 1, wherein the water-cement ratio is adjusted to 60% or less. 6. A ready-mixed concrete is prepared by mixing a lightweight aggregate, an inorganic powder, a cement, a water reducing agent and water, which are dried in a completely dry state or at a water absorption rate of 50% or less, to prepare a ready-mixed concrete. A lightweight concrete molding obtained by casting it into a formwork and curing it.