JPH0417773B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a concrete surface treatment technique for finishing the surface of concrete to a high quality.

<Conventional technology> Recently, in order to improve the quality of the surface layer of concrete structures, the inside of the formwork with micropores has been lined with a single-layer water-absorbing sheet made of polyester that has water permeability and air permeability. Breathing water (excess water) in concrete using water-absorbing formwork
A construction method has been proposed in which water and air are sucked up using a water-absorbing sheet and then discharged to the outside through micropores in the formwork.

<Problems to be Solved by the Present Invention> The conventional concrete placing techniques described above have the following problems.

(b) If the concrete is shaken during compaction,
Concrete materials separate.

The mortar paste components that have separated and gathered on the surface of the concrete pass through the water-absorbing sheet and reach the formwork surface, forming a mortar layer between the water-absorbing sheet and the formwork surface.

Therefore, if the time for demolding is delayed, the formwork and concrete structure will be firmly adhered to each other through the water-absorbing sheet, making demolding work extremely difficult.

(b) Air permeability deteriorates significantly in the area of the water absorbent sheet impregnated with mortar components, so air bubbles remain inside the concrete surface layer.

Since this cavity is difficult to detect from the outside, the concrete structure has a fatal defect.

(c) When adhering the water absorbent sheet to the formwork, the water absorbent sheet is soft and easily wrinkles, resulting in a wrinkle pattern formed on the surface of the concrete.

(d) The water absorbent sheet expands and contracts under the influence of humidity changes that occur before concrete is poured.

Therefore, it becomes difficult to adhere the water absorbent sheet to an appropriate position on the formwork.

<Object of the present invention> The present invention has been made to solve the above-mentioned problems, and is capable of recovering excess breathing water and air bubbles without adversely affecting the water-cement ratio on the surface of concrete. Moreover, it is possible to form a high-quality concrete surface. The purpose is to provide concrete surface treatment technology.

<Configuration of the Present Invention> An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

<A> Means for collecting excess water and air bubbles In the present invention, a water absorbent mold is used in which a water absorbent sheet 4 made of a laminate of a super absorbent sheet 1, long fibers 2, and a breathable sheet 3 is adhered to the inside of a formwork 5. A frame is used to prevent the formwork from sticking to the concrete structure, and excess water and air bubbles floating on the surface of the concrete are collected by the laminate.

<B> Water-absorbent sheet The water-absorbent sheet 4 is composed of a laminate of a sheet-like super absorbent sheet 1, long fibers 2, and a breathable sheet 3.

Each of these sheets 1 to 3 has water permeability and air permeability.

<C> Super absorbent sheet The super absorbent sheet 1 can be made of a flexible material with excellent water absorbency, such as a polymer gel.

That is, the super-absorbent sheet 1 is made by adhering or forming a single sheet of water-absorbing polymer gel that absorbs 2 to 1000 times its own weight of water to a film-like cloth body.

The superabsorbent sheet 1 has a large number of pores 11 on its entire surface, and these pores 11 serve as areas where air bubbles remain and spaces that allow free expansion of the polymer gel.

[Example of material for cloth body] The following materials can be used as the cloth body constituting the super absorbent sheet 1.

Organic fibers such as rayon, polypropylene, nylon, vinylon, cotton, wool, acrylic, inorganic fibers such as glass, asbestos, metal, or blends of these fibers.

[Examples of polymer gel materials] Examples of water-absorbing polymer gels include the following.

(a) Vinyl acetate-acrylic acid copolymer system (b) Starch-acrylic acid graft copolymer system (c) Starch-acrylonitrile graft copolymer system (d) Polyvinyl alcohol maleic anhydride system (e) Isobutylene-maleic anhydride system System (f) Polyacrylic acid system (g) Polyvinyl alcohol, acrylic acid copolymer The above fibers may be directly treated with a water-containing polymer gel, or they may be adhered with a water-soluble polymer such as polyvinyl alcohol. , fixing treatment may be performed using various heat-fusible fibers or hot-melt adhesives.

In particular, isobutylene maleic anhydride-based polymer gel has a moderate retardation effect on concrete.
It is desirable because it has excellent durability and weather resistance.

<D> Long fibers Long fibers 2 are used to make water absorbent sheets 4 from concrete.
This reinforcing material is strong enough to prevent breakage and elongation when peeled off.

Instead of the long fibers 2, the same material as the super absorbent sheet 1 described above may be used as long as it has water permeability, air permeability, and a predetermined strength.

The reinforcement direction and strength of long fiber 2 are as follows:
You can freely change and use the array by selecting the orientation and pitch of the array.

Note that if the water absorbent sheet 4 is not required to have strength, the water absorbent sheet may be formed without interposing the long fibers 2.

<E> Air-permeable sheet The air-permeable sheet 3 is designed to discharge the air absorbed by the super-absorbent sheet 1 without leaving it inside the super-absorbent sheet 1, and to remove the cement exposed through the pores 11 of the super-absorbent sheet 1. This sheet is intended to shield paste components just before they reach the formwork 5.

The breathable sheet 3 used has lower water absorption than the super absorbent sheet 1.

As the breathable sheet 3, for example, a cloth constituting the highly water-absorbent sheet 1 to which no water-absorbing polymer gel is attached, or a porous material based on polyethylene, polypropylene, etc. can be used.

The breathable sheet 3 has pores 31 on its entire surface.
has.

<F> Method for forming a water absorbent sheet Super water absorbent sheet 1 constituting the water absorbent sheet 4,
The long fibers 2 and the breathable sheet 3 can be laminated, for example, by the following method.

The most preferable method is to use heat-fusible fibers as the long fibers 2 or to fuse the air-permeable sheet 3 with a heat-fusible film containing heat-fusible fibers.

When manufacturing the superabsorbent sheet 1, the bonding may be performed simultaneously with the formation of the polymer gel.

Alternatively, the sheets 1, 2, and 3 coated with various hot-melt glues or water-soluble glues can be bonded together by pressing with a roll or the like.

Next, a method of treating the surface of concrete using the water-absorbing sheet 4 will be explained.

(1) Installation of water-absorbent sheet The water-absorbent sheet 4 is pasted on the formwork surface of the formwork 5 using nails, double-sided tape, or the like.

At this time, the breathable sheet 3 constituting the water-absorbing sheet 4 is attached facing inside the formwork 5.

The formwork 5 to which the water-absorbing sheet 4 is attached is assembled using the same process as the conventional method.

(2) Placing concrete Concrete 6 is poured into formwork 5.

After that, by applying vibration to the concrete 6, etc.
Compact while encouraging the rise of breathing water and air bubbles.

(3) Absorption of breathing water, etc. When vibration is applied to the concrete 6, excess water and air bubbles contained in the concrete 6 emerge on the surface layer side of the concrete 6.

The surplus water that has come to the surface of the concrete 6 is first absorbed by the super absorbent sheet 1 that constitutes the water absorbent sheet 4 and then collected.

In addition, the air bubbles emerging on the surface of the concrete 6 pass through the superabsorbent sheet 1 and then reach the air permeable sheet 3 via the long fibers 2.

The air bubbles that have reached the air-permeable sheet 3 are further discharged from the upper end of the air-permeable sheet 3 or between the joints of the formwork 5 via the pores 31 .

On the other hand, most of the mortar paste components separated by applying vibration to the concrete 6 remain in the pores 11 of the super absorbent sheet 1.

Even if this mortar paste component reaches the breathable sheet 3 through the pores 11 of the superabsorbent sheet 1, it will remain in the pores 31 of the breathable sheet 3 but will not pass through. Therefore, the mortar paste components do not reach the inner surface of the formwork 5.

In this way, most of the excess water, air bubbles and mortar components are collected by the super absorbent sheet 1, and the air bubbles that have passed through the super absorbent sheet 1 are collected by the air permeable sheet 3.
It is discharged to the outside through the pores 31.

(4) Demoulding After a predetermined curing period, the mold is removed.

Demoulding is carried out by removing only the formwork 5 with the water absorbent sheet 4 attached to the concrete 6, and then peeling the water absorbent sheet 4 from the surface of the concrete 6, or removing the contact area between the concrete 6 and the water absorbent sheet 4. If it is small, the water absorbent sheet 4 is peeled off together with the formwork 5.

After demolding, the surface layer of the concrete 6 has excess water and air bubbles collected by the water-absorbing sheet 4, so the water-cement ratio of the surface layer of the concrete 6 is reduced and the surface layer is smooth. organization becomes very dense.

Furthermore, when the formwork 5 is peeled off from the water-absorbent sheet 4, a mortar layer is not formed between the formwork surface of the formwork 5 and the air-permeable sheet 3 constituting the water-absorbent sheet 4, so the water-absorbent sheet The force required for peeling off step 4 is small.

Moreover, since the water-absorbing sheet 4 has sufficient strength, even when it is peeled off from the concrete 6, the water-absorbing sheet 4 can be prevented from breaking and can be peeled off efficiently.

Therefore, there is no need to apply a release agent such as grease to the mold surface as in the conventional method.

<Effects of the Present Invention> Since the present invention is as explained above, the following effects can be obtained.

(b) Since excess water and air bubbles can be efficiently collected, the water-cement ratio in the concrete surface layer decreases.

As a result, the strength and durability of the concrete surface layer are improved, and a high-quality finish can be achieved.

(b) Excess water and air bubbles that rise to the surface of the concrete are absorbed, eliminating the occurrence of "pockmarks" on the surface of the concrete.

As a result, a good glossy surface can be obtained on the concrete surface.

Particularly in the case of concrete with high slump and low quality, the effect of improving the "pock" is noticeable.

(c) Since the mortar paste separated by concrete compaction can be prevented from penetrating into the formwork surface, the releasability of the water absorbent sheet is improved.

Furthermore, the conventional step of applying a release agent such as grease to the mold surface can be omitted.

(d) Since the water-absorbing sheet is not stretchable and has appropriate strength, it is easy to cut the water-absorbent sheet and attach it to the formwork.

(E) Since wrinkles are unlikely to occur in the water absorbent sheet, there is no need for wrinkles to form on the surface of the concrete where the mold has been removed.

(f) Since the surface of concrete can be finished smooth by avoiding the occurrence of "pockets", the roughness coefficient of the concrete surface can be lowered.

Therefore, when designing grooves, for example, conventionally a large slope was required;
There is no need to make the slope large, which is advantageous in terms of design.

[Brief explanation of drawings]

FIG. 1: An explanatory diagram of the concrete surface treatment method according to the present invention. FIG. 2: An enlarged partial cross-sectional view of a water-absorbing formwork and poured concrete.

Claims (1)

[Claims] 1. A water-absorbent sheet made of a laminate of a highly water-absorbent sheet, a breathable sheet, and reinforcing long fibers interposed between these two sheets is attached to a formwork, and the formwork is The concrete is placed in the exposed space of the super-absorbent sheet, and the sheet is brought into contact with the water-based polymer sheet, allowing the water-absorbing sheet to absorb excess water and air bubbles that rise to the surface of the concrete. , A concrete surface treatment method that involves waiting for the concrete to harden and then removing the water-absorbing sheet and formwork. 2. A superabsorbent sheet that is breathable and has excellent water absorption; A breathable sheet that is breathable and has lower water absorption than the superabsorbent sheet; and a space between the two sheets. A water-absorbent formwork comprising: a water-absorbent sheet formed by laminating a reinforcing sheet with intervening air permeability and water permeability, and the breathable sheet constituting the water-absorbent sheet being affixed toward the surface of the formwork. .