JP2945563B2 - Release agent for concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete release agent capable of promoting the densification of a bare surface of concrete.

[0002]

2. Description of the Related Art The exposed finished surface of concrete has a drawback in that the uncured cement component on the concrete surface is washed away with the passage of time, resulting in a pock-like shape. In order to eliminate this kind of defect, a large amount of siliceous fine powder having pozzolanic activity may be mixed into concrete, but the unit price of this kind of siliceous fine powder is expensive and the construction cost is extremely high It will be.

On the other hand, on the casting surface side of a concrete casting mold, release agents such as animal and vegetable oils and metal salts thereof, heavy oil, mineral oil, paraffin, synthetic resin, etc. are used in order to improve the removability. Is applied. These are left attached to the concrete surface after removal from the mold, but are unnecessary after removal from the mold, and need to be cleaned and removed when applying a finishing material to the surface.

[0004]

Therefore, if a material which adheres to the concrete surface as a release agent and densifies the surface is used as the release agent, the exposed surface can be exposed without introducing a large amount of expensive siliceous fine powder into the concrete. Can be kept robust and smooth for many years.

[0005] For this purpose, the release agent itself migrates from the mold side to the surface layer of the concrete and impregnates it to fill the voids, and reacts with the uncured cement in the filled state to form an insoluble compound. is necessary.

The present invention has been made on the basis of the above findings, and an object of the present invention is to provide a concrete release agent capable of forming a hard and dense exposed surface on concrete.

[0007]

In order to achieve the above object, a concrete release agent of the present invention comprises a polymer having the property of being soluble in an alkali and being insoluble in water, and a pozzolanic activity mixed and dispersed in the polymer. And a mixture with silicic acid fine powder.

[0008]

With the release agent having the above structure, direct contact is avoided by the polymer present at the interface between the formwork and the cast concrete, so that the demolding becomes easy and at the same time, the uncured cement contains The polymer is eluted from the mold surface by the alkali component and impregnated into the concrete surface layer, the voids in the concrete surface layer are filled, and the surface is densified by the pozzolanic reaction of the siliceous fine powder dispersed and mixed with the polymer.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

First, the polymer defined in the present invention as being soluble in alkali and having properties unnecessary for water is an unsaturated group selected from methyl methacrylate, ethyl acrylate, butyl acrylate, vinyl acetate and styrene. Is a copolymer of an organic compound having an organic compound and an organic acid having an unsaturated bond selected from acrylic acid, methacrylic acid, and crotonic acid, which is insoluble in neutral or weakly acidic water at room temperature, and has a pH of 7 Is a resin constituting a continuous film that is soluble in alkaline water of at least 5 and is obtained by solubilizing with water or an aqueous dispersion of the copolymer obtained by emulsion polymerization or suspension polymerization with ammonia. The polymer is mainly used as a release agent at the time of demolding and as a binder for the siliceous fine powder.

The siliceous fine powder having a pozzolanic activity defined in the present invention is a fine powder material containing silicon dioxide or silicon dioxide and aluminum oxide, such as silica fume and blast furnace slag, and has no hydraulic property itself. there react at room temperature with calcium hydroxide in the presence of moisture to produce cured stable insoluble compounds, a fine powder of a so-called port Zola emission reactivity.

The siliceous fine powder contacts and reacts with the unreacted portion of the concrete surface, and has both a function of accelerating hardening and a function as a filler.

The release agent is prepared by mixing and dispersing the above siliceous fine powder in an aqueous suspension or an aqueous solution of the above polymer at an appropriate mixing ratio. The compounding ratio is set in consideration of the functionality, applicability, storage stability, and the like of each material. If necessary, additives such as a surfactant, a film-forming auxiliary, a thickener, a preservative, an antifoaming agent, and a rust inhibitor can be added.

The release agent obtained as described above is
As shown in FIG. 2A, a continuous coating 2 having a predetermined thickness is formed on the inner surface of the mold 1 by spraying or brushing the inner surface of the mold 1, that is, the concrete casting surface, and then drying.

When concrete C is poured into the form 1, strong alkaline water eluted from the cement paste of uncured concrete in contact with the inner surface of the form 1 causes
The coating 2 swells gradually and then dissolves.

The dissolved polymer impregnates the surface layer of the concrete C, and the siliceous fine powder dispersed therein also impregnates the surface layer of the concrete C. Cures this part. It also penetrates into the voids on the surface and fills this area.

When the concrete C hardens after a predetermined curing period, the mold 1 is released. At the time of this demolding, since the polymer is present at the interface, direct contact between the mold 1 and the concrete C is avoided, so that the demolding can be easily performed.

After removal from the mold, as shown in FIG. 2B, the surface hardened layer 3 composed of the polymer, the siliceous fine powder, and the cement component bonded thereto is formed to a predetermined depth of the surface layer of the concrete C. The exposed surface becomes smooth and dense, and when the concrete structure is used as the finished surface as it is, the surface can be kept firm and smooth by the surface hardened layer 3.

It should be noted that the present invention can be applied to a case where a finishing material is applied to the surface, and has a better adhesion to the finishing material as compared with a case where a conventional release agent is used. Work can also be omitted.

[0020]

As described in detail in the above embodiments, the concrete release agent according to the present invention includes:
The polymer present at the interface between the formwork and the cast concrete prevents direct contact, facilitating demolding, and at the same time, the polymer elutes from the formwork surface due to the alkali content in the uncured cement and the concrete surface layer And the surface of the concrete can be densified by the pozzolanic reaction of the siliceous fine powder dispersed and mixed with the polymer by filling the voids in the concrete surface layer.

Therefore, according to the present invention, the exposed surface can be kept robust and smooth for many years without introducing a large amount of expensive siliceous fine powder into concrete. The present invention is also effective when a finishing material is applied to the surface.

[Brief description of the drawings]

1 (a) and 1 (b) are explanatory sectional views showing the surface shapes of a mold and concrete using the release agent of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Formwork 2 Continuous coating 3 Surface reinforcement layer C Concrete

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor, Tsutomu Asami 373-3, Yorii-cho, Osato-gun, Saitama Prefecture Inventor Yoshimasa Hayashi 4-640 Shimoseito, Kiyose-shi, Tokyo Inside the Obayashi-gumi Technical Research Institute, Inc. JP-A-51-47013 (JP, A) JP-A-55-65508 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B28B 7/38

Claims (1)

(57) [Claims] 1. A concrete release agent comprising a mixture of a polymer soluble in alkali and insoluble in water, and a fine siliceous powder having pozzolanic activity mixed and dispersed in the polymer.