JPS62253869A - Concrete mold frame - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to concrete formwork, and in particular provides a formwork for use in concrete and mortaring in house construction, civil engineering work, and the like.

<Prior art> Conventional formwork is known to use plywood as is, but the concrete and mortar poured into the formwork adheres to the plywood surface of the formwork, making it difficult to remove the formwork. Because of this drawback, tar or paraffin/silicone-based release agents are applied to the plywood surface at construction sites to improve removability. In addition, in recent years, in order to prevent this concrete/mortar from adhering to the plywood surface, painted formwork has been manufactured by applying synthetic resin such as acrylic resin or urethane resin at the factory to form a coating layer on the plywood surface. (For example, Japanese Patent Publication No. 45-15064, Japanese Patent Publication No. 53-38728, Japanese Utility Model Publication No. 47-3)
Publication No. 0639).

<Problems to be solved by the invention> It is known from experience that when plywood is used as a formwork for pouring concrete, dark-colored poorly cured areas are formed at the concrete interface after the mold is released. . Since such concrete materials are unfavorable in appearance, when a wall is constructed by pouring concrete, it not only reduces the design of the wall but also significantly reduces its strength due to poor curing. In some cases, this poorly cured area is not limited to just the surface layer, but affects the depth of several ff1j, and even if a hand or object touches that area, it turns into particles and falls off in a rough manner. present.

In addition, in the case of joint painting construction on a concrete surface, the joint mortar applied to the surface, the coating material, finish coating material, tiling, etc. applied to the surface should be kept at a distance from the poorly cured area after construction. It had drawbacks such as lifting and sometimes peeling off.

The formation of these poorly hardened areas is thought to be due to harmful substances contained in the formwork plywood leaching out of the wood and inhibiting the hydration reaction of cement, but the detailed mechanism is still not fully understood. Not yet.

In conventional painted formwork, a synthetic resin coating layer is formed on the surface, which suppresses the elution of harmful substances from the wood to some extent in the early stages of use, but it is possible to avoid elution through pinholes in the painted MN. Furthermore, cracks in the coating layer due to deterioration of the coating layer, and elution from damage to the coating layer due to external force, etc., easily occur. Therefore, it could not be a means to fundamentally solve the problem of contamination of the concrete surface and inhibition of hardening due to the elution of harmful substances from the wood.

<Means for Solving the Problems> As a result of various studies on the phenomenon that the components eluted from the plywood formwork inhibit the hydration reaction of the debris and lead to poor curing, the present inventor found that the components contained in the wood Extracted components such as water-soluble cellulose, lignin, tannin, humic acid, and sugars are dissolved at the interface with the cement by the water in the cement slurry, and these extracted components release Ca'' from the cement.
, K", and Ha" to form a salt, and as a result of covering the cement particles with this salt, the subsequent hydration reaction of the cement was suppressed. In other words, normally hardened mortar solids contain 2SO.

Although there are large amounts of Na2SO4 and Ca(OH)2,
In the case of a mortar with poor hardening, the amount of these mixed together was reduced, and in the mortar with a markedly poor hardening, these were hardly present, and instead, a large amount of ettringite was observed. This is because Ha', K", and Ca2°, which should be dissolved into the liquid phase and crystallized as 2SO4, Na2SO4, and Ca(OH)z during cement hydration, are adsorbed by the above-mentioned extract components eluted from the wood, or chemically It is presumed that the excess So, 2- crystallized into ettringite because it could not be crystallized because it could not be crystallized because it could not be crystallized.

The present invention has been developed based on the above findings and further studies, and includes a concrete formwork in which a layer of paper or cloth impregnated with a metal compound is formed on at least one surface of plywood. This is what we provide.

That is, in view of the fact that in the above-mentioned conventional technology, attempts were made to prevent the elution of harmful components from the wood by forming a coating layer on the surface of the form plywood, but the results were insufficient, formation of a coating layer, etc. We have moved away from the technical concept of physically preventing the elution of wood extract components, and from a chemical standpoint, we have developed methods for preventing wood extract components from combining with free ions from cement to form complex salts. I have thought about it a lot.

As a result, by pre-binding wood extract components with metal ions that form complex salts that are more stable than these free ions, the wood extract components are more stably chelated with the metal ions, resulting in free release. It has been found that bonding with ions can be prevented. Based on this, a patent application was filed on April 18, 1986 for plywood in which at least one surface of the veneer was coated or impregnated with powder or aqueous solution of a metal compound, but conventional plywood was used. However, it was confirmed that substantially the same effect could be achieved by forming a paper or cloth layer impregnated with a metal compound on at least one surface thereof, and the present invention was achieved based on this finding.

The concrete formwork according to the invention is obtained as follows.

After applying an arbitrary adhesive to the surface of the plywood using a coating device such as a roll coater, paper or cloth impregnated with a metal compound is laminated on the adhesive-coated surface and bonded by pressure. This paper layer or cloth layer must be adhesively formed on at least one surface of the plywood.

Paper or cloth impregnated with a metal compound can be prepared by a known method such as a coating method or a dipping method. In other words, an aqueous solution of a metal compound is applied to any paper or cloth, or the paper or cloth is impregnated with the metal compound. After soaking in an aqueous solution of a metal compound, it is dried and adhered to the surface of the plywood.

The impregnation treatment of the paper or cloth with the metal compound may be carried out after the paper or cloth is top-adhered to the plywood surface using an optional adhesive, that is, the plywood is obtained with a paper or cloth layer formed on at least one surface. The formwork of the present invention can also be obtained by later coating and impregnating the surface paper/fabric layer with an aqueous solution of a metal compound and then drying it.

The metal compound used in the present invention is a compound that combines with extracted components such as cellulose, lignin, tannin, and sugars in the wood of plywood to form a highly stable complex. When used, it prevents the wood extract components from combining with free ions from the cement to form complex salts in the presence of water, and instead allows them to combine with more stable metal ions to achieve the desired effect. Therefore, the metal compound used should elute metal ions that are soluble in water and have a higher stability than cement free ions.
It must be able to combine with wood extract components to form poorly soluble complex salts. That is, it forms a chemically stable complex salt by combining with the wood extract components eluted into the moisture in the wood or by subsequent moisture adhesion due to rainwater, etc. For example, one or more of sulfides, chlorides, hydroxides, etc. of iron, copper, zinc, lead, aluminum, etc. can be used alone, in combination, or in a mixture.

A plurality of through holes may be formed in the plywood, in which case one or both ends of the through holes are closed with paper/cloth impregnated with the metal compound.

<Function> Since a layer of paper or cloth impregnated with an aqueous solution of metal compounds is formed on the plywood surface, wood extracted components such as cellulose, tannin, lignin, and sugars are eluted from the metal compounds on the plywood surface. It combines with to form a stable complex salt.

Therefore, the formation of complex salts due to the combination of these wood extract components and free ions from cement is suppressed. Therefore, even when this is used as a concrete formwork, curing inhibition will not occur.

Additionally, if through holes are formed in the plywood, excess water in the concrete slurry will be discharged through the through holes through the paper/fabric layer on the surface of the plywood to provide the optimum amount of water necessary for the cement hydration reaction. The amount of water is easily adjusted, increasing concrete strength.

Furthermore, the wood extract components are eluted by the water passing through the through holes, but at the same time, they are bonded by the metal compounds eluted from the surface paper/fabric layer to form a stable complex inside.
The impact on the concrete surface will be suppressed.

Test Example> The effects of various metal compounds on the inhibition of cement hardening by wood extract components were tested.

Cement: Rinjun sand = 1 = 2 mixed, various solutions were mixed and kneaded at a water/cement ratio of 0.65 to prepare various green mortars, and these were placed in iron molds (1xl
x4 cm), temperature 20℃, temperature approx. 8oz
After curing for one day in a constant temperature bath, the samples were cured for a predetermined period of time in water at 20°C to obtain various mortar specimens. The blended solution was prepared using 18 sheets of lOxlOx1cm plywood with saturated Ca (
011) Various copper compounds, zinc compounds, lead compounds, and aluminum compounds were added to the wood extract obtained after soaking in the two solutions for 48 hours at 0.1 $ and 0.3%, respectively.

0.5z and 1. It was added at a ratio of oz. For comparison, mortar specimens prepared by blending solutions to which these metal compounds were not added were also prepared.

Table 1 summarizes the results of measuring the compressive strength of these mortar specimens after curing and hardening for a predetermined period of time.

・, Table 1 Copper chloride ◎ ○ ゛ O(0,3
~0.5) Sulfur i! 2 Copper ◎ ○ O(0
,1~1゜0) Copper hydroxide OO× Zinc chloride O× × Zinc sulfate ◎ ◎ ◎(0,1
~0.3) <0.1~0.3) (0,3~0.
5) Zinc hydroxide O× × Lead chloride ◎ ◎ ◎(0,1
~1.0> (0,3~1.0) (0,3~1.
0) Lead sulfate O◎ ◎ (0,1~0.5) (0,1~0.5) Lead hydroxide
0 0 x aluminum chloride
◎ ◎ ◎(0,1~1.0) (
0.1~0.5) (0.3~0.5) Aluminum sulfate
◎ ◎ O (0.1~1.0)
(0,3~1.0) Aluminum hydroxide O×
× Ferric chloride O◎ ◎ 0.1-1.0 0.1-0. (0,320,5) In terms of compressive strength in Table 1, X marks indicate mortar with no increase in strength compared to mortar prepared using a solution without metal compound additives, O marks indicate The ◎ mark indicates the metal with a slight increase in strength, and the ◎ mark indicates the metal with a significant increase in strength.The numerical value shown in parentheses under the ◎ mark indicates the metal when the strength development reached its maximum. This is the amount of compound added.

From the results shown in Table 1, although the effects are not necessarily constant depending on the type of metal compound and the amount added, it is generally possible to suppress the cement hardening inhibiting effect of wood extract components by incorporating these metal compounds. It is known that it is possible.

In particular, copper compounds include copper chloride and steel sulfide, zinc compounds include zinc sulfate, lead compounds include lead chloride and lead sulfate, aluminum compounds include aluminum chloride and aluminum sulfate, and iron compounds include iron chloride. It was found that each of them had a remarkable suppressive effect.

Furthermore, when we examined the microstructures of the mortar specimens that exhibited these remarkable inhibitory effects using a scanning electron microscope, we found that in all cases, gel-like particles were adsorbed and polymerization occurred due to chemical bonding. fibrous or granular
A lumpy product was observed. This is Fe, which has greater stability than the ions Ca'', Ni', Ha'', etc. released from cement into the liquid phase.

Metal ions such as Cu, Zn, and Pb+^1 were eluted from the added metal compound, and it was determined that these metal ions were complex salts produced by combining with wood extract components.

<Example> Copper sulfate, zinc chloride, aluminum chloride, alum, and ferric chloride were used as metal compounds, and 10% of each of these was used.
1 aqueous solution and 2 oz aqueous solution were applied and impregnated onto 35 g/x2 thin paper using a roll coater at a coating amount of 40 g/x2.100 y/x2. These metal compound-impregnated papers were laminated on one side of a 3x ax 12ztJ* plywood board made of Melabi material, and the coating amount was 30g.
Various treated plywoods were prepared by adhering with an adhesive mainly composed of vinyl acetate coated with a coating composition of /x2.

For comparison, two untreated sheets were obtained under the same conditions using paper that was not impregnated with an aqueous solution of these metal compounds Metal compound Concentration Coating amount Concrete
Type of hardening inhibition depth z) (I2)
(R received) - Untreated plywood - Dark throughout 2-4 treated plywood Copper sulfate 1040
Partially slight brown 0.2-0.32040n1 100IIt Zinc chloride 10 40n
No 100 Tsuno I No 20 40 -ノ
! ! 100 horns 1 aluminum chloride 1040 None O~0
2100n horn 2040rt horn l QQ n n alum 1
040 Horn Horn 100
n n100n horn ferric chloride 1040 horn 100 horn 2040 no n plates were also prepared.

These treated plywood and untreated plywood were used as concrete formwork, and the molds were removed three days after concrete pouring, and the condition of the concrete surface was comparatively observed to examine the effect of metal compound impregnation. The results are shown in Table 2 below.

As is clear from the results shown in Table 2, concrete hardened and cured in a mold using untreated plywood not impregnated with metal compounds has a depth of 2 to 4 cm from the surface. Curing inhibition was detected and the entire surface exhibited a deep dark brown color, whereas in the paper on the plywood surface impregnated with a metal compound according to the present invention, there was almost no curing inhibition and the surface color was generally uncontaminated. It was something that didn't exist.

<Effects of the Invention> According to the present invention as described above, extracted components such as cellulose, lignin, tannin, and sugar in the veneer are extracted from the metal impregnated into the paper or cloth layer formed on the surface of the formwork plywood. Since it binds with the compound and forms a highly stable insoluble complex inside, the elution of the extract component 5 can be sufficiently suppressed. Therefore, concrete hardening is not inhibited.

In addition, these wood extract components combine with the metal ions eluted into the water contained in the wood to form an internal insoluble complex, so the extract components are not dissolved by subsequent moisture adhesion due to rainwater, etc. Furthermore, even if it is dissolved, it binds to the metal compound coated or impregnated within the veneer to prevent its elution, and the surface of the plywood is not contaminated by the extracted component.

Furthermore, even when water permeates through the cement slurry, extracted components from this material will not be eluted, and even if they are dissolved, they will combine with the metal compounds impregnated in the surface paper/fabric layer and will not elute. Therefore, the curing inhibition caused by the extracted components can be effectively suppressed and the design is not impaired. Therefore, the present invention can be effectively used especially in the case of interior wall construction and repainting construction. Can be done.

In addition, by forming through holes in the plywood, excess water during concrete pouring is discharged from the through holes, resulting in a generally appropriate moisture content, making it possible to produce concrete with excellent strength.

Claims (3)

[Claims] (1) A concrete formwork characterized in that a layer of paper or cloth impregnated with a metal compound is formed on at least one surface of plywood. (2) The metal compound is characterized in that it consists of one or more substances selected from sulfides, chlorides, and hydroxides of iron, copper, zinc, lead, and aluminum;
A concrete formwork according to claim 1. (3) The concrete formwork according to claim 1 or 2, wherein a plurality of through holes are formed in the plywood.