JPH01167286A - Sealing compound for curing mortar concrete - Google Patents

Abstract

PURPOSE:To obtain the title sealing agent having excellent preventing action on occurrence of cracks caused by drying in a process up to setting, consisting of an ethylene-vinyl acetate copolymer resin emulsion and butylcarbitol acetate. CONSTITUTION:A sealing compound for curing motar concrete consisting of (A) an ethylene-vinyl acetate copolymer resin emulsion and (B) butylcarbitol acetate. An ethylene-vinyl acetate copolymer resin emulsion having 5-40wt.% ethylene content is preferable as the components A and can be blended with a small amount of a third monomer (e.g. acrylic acid ester). The amount of the component B blended is properly >=2 pts.wt. based on 100 pts.wt. solid content of the component A. The component A is blended with the component B or the component B and water in such a way that the concentration of solid content of the component A becomes about 25-45wt.% to produce a sealing compound. The amount of the sealing compound applied is preferably >=80g/m<2> calculated as solid content.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a sealant for mortar/concrete curing, and more particularly, to a sealant for mortar/concrete curing, or
This invention relates to a sealant for curing mortar and concrete that prevents the occurrence of cracks due to drying during molding and hardening.

[Prior Art and Seven Points] Conventionally, when mortar/concrete is subjected to strong drying from pouring to setting and hardening, cranking occurs due to plastic shrinkage.

In particular, crow compound concrete with little breathing, and for example, a slump value of 5c! Hard-mixed concrete with a hardness of n or less, highly fluidized concrete, which does not cause any breathing, cemented concrete with a C value of 5 seconds or more, mortar concrete with a high performance water reducer added, etc. The tendency of number seven is clearly strong. For example, mortar/concrete added with a high-performance water reducer is non-breathing, has a thick consistency, and the mortar/concrete begins to dry as soon as it is poured, causing the mortar/concrete to turn as if it had been plastered. A crack will appear within a few minutes. This crack has a width of about 2 to 6 cm, and at the same time, it grows into a feldspar of tens of σ to several meters and reaches a depth of 1 oclIL or more.

In order to prevent this cracking, it is a good idea to take measures to prevent the moisture in the mortar and concrete from evaporating after pouring the mortar and concrete, or after a suitable period of time. Stretch X, vinyl or polyenergetic), 113N raw pine, etc. to mortar/concrete blush ii! It is possible that there will be strong contact. However, these methods are avoided when the area to be poured is large or when careful finishing is not a concern, as the work becomes complicated and marks such as curing mats are left instead of marks.

Therefore, as an alternative curing method, a curing method using a polymer emulsion coating has not been considered or implemented (
Special Publication No. 62-116 @).

Japanese Patent Publication No. 62-116 discloses an invention in which a specific enalene-vinyl acetate monopolymer resin emulsion is used as a sealant. It is difficult to prevent cracks in highly viscous mortar and concrete with this type of sealant, and the lower the temperature, the thicker the cracks become.Especially at temperatures below 15°C, it is difficult to prevent cracks from occurring with this type of sealant. The problem is that it has no effect at all.

The reason for the seventh reason is not clear, but it is presumed that the film formed on mortar/concrete is not dense and has thick moisture permeability, and that these tendencies become thicker at low temperatures. .

The occurrence of ri-y) is thought to be due to the evaporation of water from the mortar and concrete and the accompanying shrinkage, and the excessive drying rate (shrinkage rate) within the mantissa hours of pouring. Therefore, we believe that the only way to prevent the occurrence of cranks is to form a uniform and dense film on the surface of mortar concrete.After various studies, we found that ethylene-vinyl acetate copolymer resin emulsion and bunalcargitol acetate were used. This study led to the discovery that the occurrence of cranks can be reduced or prevented when used in combination with this method.

[+ step to solve the gap]

That is, the present invention is a sealant for mortar/concrete curing comprising an enalene-vinyl acetate monopolymer resin emulsion and butyl carbitol acetate.

The present invention will be explained in detail below.

Enallen in non-invention! The rl-vinyl acid comonomer resin emulsion (hereinafter referred to as EVA) is a mixture of ethylene and vinyl acetate heptanomer emulsion, and preferably has an ethylene content of 5 to 401%. or,
A small amount of a third monomer (for example, an acrylic acid ester cap, an unsaturated carboxylic acid monomer, an amide monomer, a halogenated olefin monomer, a polyfunctional vinyl monomer, etc.) There are no particular limitations, and it is possible to use those that have been added and polymerized, or those that have been added with polyvinyl alcohol to stabilize the emulsion.

These commercially available products usually have a solid content concentration of 50 to 6SilU.
It is manufactured as a highly viscous solution in a water-based dispersion system, but as it is, the viscosity is so high that it cannot be applied as a sealant with a spray gun. Therefore, it is possible to spray 1,000
Use by diluting with butyl carbitol acetate (hereinafter referred to as BCA) or it and water to a level of 0 CpB or less.

In order to compensate for incomplete film formation in the emulsion, solvents with medium to high boiling points such as cellosolves, calpitols, and alcohols are used as protective agents.
@b Aqueous emulsion, solubility W+ degree in water is 1 to 15
Those with a hydrophilic level of ``an offer at the level of a prize officer'' work effectively.

The amount of BCA used should be 2N parts or more per 100 parts by weight of the solid content of EvA, and the solid content of EvA should be 25 to 45 parts by weight.
It is diluted with BCA or a combination of BCA and water so that it becomes N. The larger the amount of BCA, the more moisture-impermeable and dense film will be formed, but if it is less than 23, the effect will become small and undesirable.

Furthermore, if the solid fraction to Ev is set at 25 to 45% by weight, if it is less than 25% by weight, the effect of preventing crack generation will be small even if the amount of spraying is increased. If the concentration exceeds 100 degrees, even if it can be sprayed, the effect of preventing the occurrence of cracks will be limited and it will be uneconomical, which is not preferable. EVA and B
The amount of CA Kaunaru mortar/concrete curing sealant to be sprayed is preferably 80g/rrL2 or more per liter, and 1
20-200g/77L2 is more preferable.

As mentioned above, the EVA which is the base of the present invention is not subject to any restrictions on the ethylene content, etc., but from the viewpoint of increasing the denseness of the film, the ethylene content is preferably 20% by weight or more.
The more the better.

〔Example〕

The present invention will be explained in detail below with reference to Examples. Note that unless otherwise specified, percentages are by weight.

Example: Ordinary portland cement, river sand and high performance water reducer were used in a weight ratio of 0:150:1.0.
/C30%, flow value 280-30 [1 ml mortar was prepared. Set, seven 15X3Ll×deep'g
Approximately 5.5 kg is packed into a 6 cm bento box-shaped iron plate form, and EV
As shown in Table A7, the mixture was arbitrarily diluted with BCA and water, and the amount of water evaporated was measured in a room at 5°0 by varying the amount of spraying. If there is a gap between the mortar and the formwork due to shrinkage, it is easy to predict that a crank will occur even in practice, so check for the presence or absence of the gap, and check the length of the plate where the gap has occurred. I measured the gap between both ends. The results are also listed below.

In addition, toilet materials are shown below.

[Materials used]

O Ordinary Portland Cement: Andes Cement 0 Sand: Wragata Prefecture Himekawa river sand, F M 2.9
30 High-performance water reducing agent: Daiichi Kogyo Yakuhin Co., Ltd., product name "Cellflow 110PJ, EVA-α": Denki Kagaku Kogyo Co., Ltd., product name [Denka EVA Tex #50] (Contains 20% ethylene, solid content 55%) EVA −β: Denki Kagaku Kogyo Co., Ltd. product name “Denka EV”
``Hitotex #87'' (Contains 10% ethylene, 55% solid content) OBOA: Kishida Kagaku@) 1st Class Reagent Comparison Example The same procedure as in Example was used except that the composition shown in Example 1 was used. Add the results to the batter = a As is clear from the table, in the comparative example, the atmosphere was at a low temperature, so the amount of evaporated water was not large, but the initial drying time of 3 to 5 hrs was relatively large. It is shown that the formwork shrinks and gaps open at both ends of the formwork.

In the examples of the present invention, the initial drying rate was slow, the amount of water repelled was suppressed by 6, and the amount of shrinkage was small or not shown at all.

〔Effect of the invention〕

As shown in the examples above, the use of the antifouling agent for mortar and concrete curing of the present invention forms a dense film and suppresses the amount of water evaporation as a whole, resulting in the occurrence of cranks. It has the effect of eliminating the

Patent applicant Denki Kagaku Kojo Co., Ltd.

Claims (1)

[Claims] A sealant for mortar and concrete curing consisting of an ethylene-vinyl acetate copolymer resin emulsion and butyl carbitol acetate.