JPH08337458A - Cement composition for embedment type frame and embedment type frame using the same - Google Patents

Abstract

PURPOSE: To obtain an embedment type frame for concrete placement having high bending strength, low shrinkage on drying and excellent durability by using a specific cement compsn. CONSTITUTION: This cement compsn. contains (A) b) 3 to 30 pts.wt. gypsum, c) 0.5 to 5 pts.wt. shrinkage decreasing agent and d) <=5 pts.wt. high-performance water-reducing agent consisting essentially of any of a polyalkyl allyl sulfonate system, melamine formalin resin sulfonate system, arom. amino sulfonate system and polycarboxylate system in a) 100 pts.wt. cement and (B) contg. broad end metallic fibers having the fiber length of 1 to 60mm, a fiber width of 0.1 to 5mm and the broad parts at both ends of the fiber width of 1.5 to 10 times the fiber width at 0.5 to 5 pts.vol. in total 100 pts.vol. of the cement compsn. and aggregate. (C) The embedment type frame is produced by kneading the cement compsn. and <=40 pts.wt. water and 100 to 500 pts.wt. aggregate for general concrete per 100 pts.wt. cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a cement composition for mortar or concrete pouring embedded formwork used in the field of civil engineering and an embedded formwork using the same.

[0002]

2. Description of the Related Art Generally, in the case of placing mortar or concrete in civil engineering construction work, a formwork,
Generally, a plywood formwork called a plywood formwork is used. However, in recent years, the reduction of tropical rainforests due to felling of the South Sea material, which is the material for this plywood form, has become a major international problem, and there is a strong demand for restrictions on the use of South Sea material in order to protect the global environment.

Further, since the plywood form is made of a natural material, it is likely to be warped or twisted, and the extraction of lignin or the like from the inside of the plywood form causes the curing failure of the mortar or concrete surface. was there.

On the other hand, there is manufactured a cement-based buried formwork in which a formwork is assembled at a construction site and mortar or concrete is placed in the formwork to integrate the mortar or concrete with the formwork. This buried formwork is less likely to be corroded or deteriorated, and is less likely to warp or twist, and there is no problem such as mortar or concrete surface hardening failure due to extraction of lignin from inside like plywood formwork. Moreover, since it is not necessary to remove the mold, attention has recently been paid to eliminating labor shortages and reducing construction costs.

The performance required for the buried formwork is that the formwork has a strength to withstand lateral pressure when mortar or concrete is placed, the workability of assembling the formwork is good, and the formwork is easy to transport. In particular, it is important to have a high bending strength. In addition, durability such as salt resistance and freeze-thaw resistance, which requires a small amount of drying shrinkage and a small chlorine ion permeability. It is necessary to have good performance. However, originally, the bending strength of mortar or concrete was about several tens of kgf / cm ² , and it was not possible to satisfy the performance required for the buried formwork.

Therefore, attempts have been made to improve the bending strength by combining mortar or concrete with a fiber material such as steel fiber, glass fiber, carbon fiber, and organic fiber such as vinylon or nylon. However, since the adhesive force between the matrix of mortar or concrete and the fibrous substance is small, the reinforcing effect by the fibrous substance is not sufficiently exerted, the bending strength is not sufficient, the drying shrinkage amount is large, and the durability is poor. Problems such as these were not solved.

Further, there are concrete impregnated with resin for improving the bending strength, and those mainly composed of resin, but the drying shrinkage is large, the durability is poor, and the material cost and the manufacturing cost are high. There was a problem such as
1-172965 and JP-A-3-07065).

As a result of various efforts to solve the above problems, the present inventor has completed the present invention by finding that the above problems can be solved by using a specific cement composition. Came to.

[0009]

That is, the present invention provides a cement composition for an embedded formwork containing cement, gypsum, a shrinkage-reducing agent, a high-performance water-reducing agent, and a metal fiber having wide ends. Yes, it is a buried formwork using it.

Hereinafter, the present invention will be described in detail.

The cement used in the present invention is JIS
R 5201 stipulated, ordinary, early strength, super early strength, various types of Portland cement such as moderate heat, various Portland cement, blast furnace slag, fly ash, or various mixed cement blended with silica, JIS Cement containing blast furnace slag more than the standard can be used, and blast furnace slag-fly ash-Portland cement-based cement and low heat-generating cement mainly containing dicalcium silicate clinker can be used.

The gypsum used in the present invention reacts with the calcium aluminate present in the cement and is a needle-like crystal, which fills the voids to form a dense structure, which improves the bending strength and the drying shrinkage amount. It produces ettringite that is small and has good durability. Specifically, dihydrate gypsum, hemihydrate gypsum, type II anhydrous gypsum,
And type III anhydrous gypsum, natural gypsum produced naturally, chemical gypsum such as gypsum phosphate, drainage gypsum, and gypsum produced by hydrofluoric acid, or anhydrous gypsum obtained by heat treatment of these is used. It is possible and is not affected by the type and amount of impurities normally contained. And type II anhydrous gypsum is particularly excellent in terms of strength development and workability, and usually does not leave unreacted matter, so use of type II anhydrous gypsum pulverized to have a Blaine specific surface area of 3,000 cm ² / g or more. Is preferred. Further, as a product mainly composed of type II anhydrous gypsum, it is also possible to use the product name “Σ1000” manufactured by Chichibu Onoda Cement Company or the Denki Kagaku Kogyo Co., Ltd. or the product name “Σ5000” manufactured by the Denki Kagaku Kogyo Co., Ltd. The amount of gypsum used is preferably 3 to 30 parts by weight with respect to 100 parts by weight of cement.
-20 parts by weight is more preferred. If the amount is less than 3 parts by weight, the amount of ettringite produced is small, and bending strength, drying shrinkage, and durability may decrease. If the amount exceeds 30 parts by weight, the amount of ettringite produced is large, resulting in abnormal expansion over a long period of time. It may happen.

The shrinkage-reducing agent used in the present invention is one having an ability to reduce the surface tension of the solution in a strong alkaline solution, such as a lower alcohol alkylene oxide adduct or an ether type nonionic surfactant. Yes, as a commercial product, the trade name "Tetra Guard" manufactured by Nippon Kasei Co.,
An example of the product name is "SK Guard" manufactured by Denki Kagaku Kogyo. The use amount of the shrinkage reducing agent is preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of cement. If it is less than 0.5 parts by weight, the drying shrinkage may be large, and if it exceeds 5 parts by weight, the bending strength may be lowered.

The high-performance water-reducing agent used in the present invention is a surfactant having a large dispersibility without excessive delay of setting or excessive air entrainment even when added in a large amount to cement, and the cement mixture Is essential to obtain a low water ratio, and has a greater water reduction rate than conventional water reducing agents such as lignin sulfonates. Generally, a commercially available high-performance water-reducing agent contains a polyalkylallyl sulfonate-based, melamine formalin resin sulfonate-based, aromatic amino sulfonate-based, or polycarboxylate-based as a main component. In addition, there are mixed types of these. Examples of the polyalkylallyl sulfonate-based high-performance water reducing agent include methylnaphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, and anthracene sulfonic acid formalin condensate, and the like, as commercially available products, manufactured by Kao Corporation. Product name "Mighty 100",
"Mighty 150", "Mighty 2000" series, etc., Daiichi Kogyo Seiyaku Co., Ltd. product name "Cellflow 110P", Takemoto Yushi Co., Ltd. product name "Pole Fine 510N", etc., Sunflow product name " Typical examples are "Sunflow PS" and "Sunflow HS700", as well as the product name "FT-500" manufactured by Denki Kagaku Kogyo Co., Ltd. Also, as high-performance water reducing agents based on melamine formalin resin sulfonate, trade names "Melment F-10" and "Melment F-20" manufactured by Showa Denko KK, and trade name "FT-3S" manufactured by Denka Grace Co., Ltd. Etc. Further, as the aromatic aminosulfonate system, there is a product name “Palic 200” series manufactured by Fujisawa Pharmaceutical Co., Ltd. Further, in the polycarboxylic acid salt system, olefin-maleic acid copolymer system, alkenyl ether-maleic anhydride copolymer system,
For example, there are acrylic acid-acrylic acid ester copolymer systems such as carboxyl group-, sulfonic acid group-containing multi-component polymers and polyether carboxylic acid salt-based polymers, and these include hydrolyzable polycarboxylic acid to enhance slump retention. Examples include commercial products of which cross-linked products have been added. Commercially available products such as Denka Grace's product names "Super 200" and "Super 200W", and Takemoto Yushi Co., Ltd.'s product name "Tupor HP1"
1 ", Posolis Bussan product name" Reobuild SP-8HS "
And the like series. The amount of high-performance water reducing agent used is
It is preferably 5 parts by weight or less, and more preferably 0.1 to 3.0 parts by weight in terms of solid content, relative to 100 parts by weight of cement. If it exceeds 5 parts by weight, the water reducing effect may not be accompanied by an increase in the amount used.

The metal fibers having wide ends as used in the present invention are those whose ends are wider than the fiber width of the central part and whose both ends are wider than the fiber width of the central part. Those are preferable. The material of the metal fiber having a wide end is not particularly limited, and the durability required as an embedded formwork, in particular, is appropriately selected depending on the need for salt resistance, and usually,
Stainless steel or steel is used. The metal fibers having wide ends have a fiber length of 1 to 60 mm, a fiber width of 0.1 to 5 mm, and further, wide portions at both ends of the fiber are preferably 1.5 to 10 times the fiber width. If the fiber length is less than 1 mm, the fiber width is more than 5 mm, or the wide portions at both ends of the fiber are less than 1.5 times the fiber width, the reinforcing effect due to the metal fibers may not be recognized, and the fiber length is more than 60 mm.
If the fiber width is less than 0.1 mm or the wide portions at both ends of the fiber are more than 10 times the fiber width, the fibers are likely to be entangled with each other, and it may be difficult to disperse the metal fibers. The amount of the metal fiber having wide ends is preferably 0.5 to 5 parts by volume in a total of 100 parts by volume of the cement composition for buried formwork and the aggregate. If it is less than 0.5 parts by volume, the bending strength may be low, and if it exceeds 5 parts by volume, the dispersibility of the fibers may be deteriorated.

The embedded formwork of the present invention can be produced by kneading a mixture containing cement, gypsum, a shrinkage-reducing agent, a high-performance water-reducing agent, and metal fibers having wide ends with water.

The amount of water used is preferably 40 parts by weight or less with respect to 100 parts by weight of cement. If it exceeds 40 parts by weight, bending strength, drying shrinkage, durability, etc. may be poor.

Further, in the present invention, it is possible to use an aggregate used in general concrete. As the aggregate, river sand, river gravel, crushed sand, crushed stone, sea sand and the like can be used. The amount of aggregate used is preferably 100 to 500 parts by weight, and more preferably 150 to 300 parts by weight, based on 100 parts by weight of cement. If it exceeds 500 parts by weight, bending strength and durability may be poor.

Further, in the present invention, various admixtures can be used in combination. As the admixture, for example, silicon, a silicon-containing alloy, and silica fume by-produced when producing zirconia, slag by-produced by metallurgy and metal refining, for example, crushed slag obtained by rapidly crushing blast furnace slag and the like, Inorganic powder such as fly ash, calcium carbonate, silica gel, titanium oxide, and aluminum oxide,
Fibrous materials such as glass fiber, carbon fiber, and organic fiber,
The purpose of the present invention is to provide one or more of high-molecular polymer emulsions and latexes, colorants and pigments, rust preventives, thickeners, water retention agents, waterproofing agents, foaming agents, foaming agents, and defoaming agents. It is possible to use in combination within a range that does not substantially inhibit.

The method for producing the embedded formwork of the present invention is not particularly limited, and may be a conventional method such as cement, gypsum, a high performance water reducing agent, a shrinkage reducing agent, a metal fiber having wide ends, and water. Furthermore, if necessary, aggregates and various admixtures can be mixed in a kneading device, and then the mixture can be produced by casting or the like. As a kneading device for each material, there are various mixers such as a tilt cylinder mixer, a forced biaxial mixer, an omni mixer, and a blade mixer.

The order of adding the materials is as follows. Cement, gypsum, aggregate, water, and shrinkage reducing agent, and if necessary, various admixtures are added and kneaded, and finally metal fibers having wide ends are added. By kneading, the amount of water used can be reduced by about 5 to 10%, and it is possible to manufacture an embedded formwork exhibiting higher bending strength, lower shrinkage, and higher durability. In the manufacturing of buried formwork, by mixing materials other than high performance water reducing agent in advance and adding the high performance water reducing agent at the end, it is possible to further reduce the amount of water used by about 5 to 10%, resulting in higher bending strength. It becomes possible to manufacture an embedded formwork exhibiting low shrinkage, and high durability.

Further, in general, in manufacturing a product, it is often required to improve productivity, and therefore, accelerated curing such as steam curing or autoclave curing is often carried out, but bending strength, dry shrinkage, and It does not cause any problem in durability or the like.

[0023]

EXAMPLES The present invention will be further described below with reference to examples of the present invention, but the present invention is not limited thereto.

Example 1 2 parts by weight of a shrinkage reducing agent, 2 parts by weight of a high performance water reducing agent, 195 parts by weight of an aggregate, and 23 parts by weight of water per 100 parts by weight of cement, and further cement, gypsum, and shrinkage reduction Mixing agent, high-performance water reducing agent, and metal fiber in a total of 100 parts by volume, 2 parts by volume of metal fiber and gypsum shown in Table 1 are mixed and manufactured by Yamanaka Co., Ltd.
Mixing was performed for 5 minutes with "Type 0". When kneading, mix cement, gypsum, aggregate, and water for 30 seconds, add high-performance water-reducing agent and shrinkage-reducing agent, mix for 2 minutes, add metal fibers and knead for 3 minutes, and mix with 10 × It was poured into a 10 × 40 cm mold and steam-cured at 65 ° C. for 4 hours to prepare a test piece. Using this test piece, the bending strength, the amount of drying shrinkage, and the amount of permeation, which is an evaluation in the salt resistance test, were measured. The results are also shown in Table 1.

<Materials used> Cement: Normal Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. Gypsum: Type II anhydrous gypsum manufactured by Sankei Gypsum Co., Ltd. High-performance water reducing agent: Product name “Super 20” manufactured by Denka Grace Co., Ltd.
0 ", solid content 18% by weight Shrinkage reducing agent: Denki Kagaku Kogyo Co., Ltd. trade name" SK Guard "Metal fiber: Metal fiber with wide ends, Nippon Yakin Kogyo Co., Ltd., stainless steel, fiber length 22mm, fiber diameter 0.5mm, specific gravity
7.9 Aggregate: Niigata Prefecture Himekawa river sand and Himekawa river gravel (Gmax = 13
mm) weight ratio 6/4 mixture water: tap water

<Measurement method> Bending strength: Specimen was cured in water for 28 days and manufactured by Maruto Manufacturing Co., Ltd.
Bending strength is measured according to JIS A 1106 using a 30t universal testing machine Dry shrinkage: According to JIS A 1129, the specimen is cured for 28 days in water and then conditioned for 6 days at 20 ° C-60% RH. Hold for a month and measure the amount of shrinkage Penetration: Salt resistance test, test specimens were cured in water for 28 days,
After soaking in artificial seawater at 20 ° C for 8 hours, 60 cycles of accelerated curing with hot air at 50 ° C for 16 hours of drying were performed for 60 cycles, and the permeation amount of chlorine ions was measured.

[0027]

[Table 1]

Example 2 The same procedure as in Example 1 was carried out except that 15 parts by weight of gypsum and a shrinkage reducing agent shown in Table 2 were mixed with 100 parts by weight of cement. The results are also shown in Table 2.

[0029]

[Table 2]

Example 3 15 parts by weight of gypsum was mixed with 100 parts by weight of cement. Furthermore, cement, gypsum, shrinkage-reducing agent, high-performance water-reducing agent, and metal fiber in a total of 100 parts by volume were used. The same procedure as in Example 1 was carried out except that the metal fibers shown in 3 were blended. The results are also shown in Table 3.

[0031]

[Table 3]

[0032]

EFFECTS OF THE INVENTION By using the cement composition for buried formwork of the present invention, it is possible to obtain a buried formwork for concrete pouring having performances such as high bending strength, small drying shrinkage, and excellent durability. .

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Claims (2)

[Claims] 1. A cement composition for an embedded formwork, which comprises cement, gypsum, a shrinkage-reducing agent, a high-performance water-reducing agent, and a metal fiber having wide ends. 2. An embedded formwork using the cement composition for an embedded formwork according to claim 1.