JPH1081578A - Curing of concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems on the conventional concrete aging, particularly during the cold midwinter, that there is a limitation in the freezing prevention only with heat-insulating sheets, while in the case that the spaces surrounded with insulating sheets are heated with heaters, frequent times of water scattering are required because the concrete surfaces tend to become excessively dry with increased complication in its control. SOLUTION: This concrete aging process comprises covering the exposed faces 11 of young-age concrete 10 with fiber sheets 12 made of a water- absorbing polymer, which is allowed to absorb water. According to this concrete- aging process, the application of fiber sheets becomes easy and moisture is always fed to the exposed faces. In addition, since the water held in the fiber sheets 12 does not so easily diffuse into the air, the operations for supplying water such as scattering can be reduced in the frequency. In addition, when it is applied to the concrete during cold midwinter, the frozen layer 13 having a temperature-insulating effect and air layer 14 are formed, when the polymer fiber sheets 12 are frozen, thereby preventing the concrete 10 from being frozen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for curing concrete, and more particularly to a method for curing concrete that is effective for cold concrete.

[0002]

2. Description of the Related Art When concrete hardens due to the hydration of cement and the surface of the concrete dries rapidly, water is drawn from the concrete inside,
Sufficient hydration may not occur. Also, since the hydration of cement is a chemical reaction, the lower the temperature of the concrete, the slower the reaction, the more the strength increases (apart from long-term strength), the concrete freezes before it hardens and becomes permanent. May be damaged.

In order to prevent such a phenomenon, after the concrete is poured, the exposed surface is kept in a wet state to prevent moisture from evaporating from the inside concrete and to provide a sufficient humidity to sufficiently exert a hardening action. In order to maintain the temperature and thereby minimize the occurrence of cracks and the like due to drying shrinkage, concrete curing work is performed.

[0004] Further, in such a concrete curing operation, since the strength of the concrete is remarkably enhanced in the concrete of young age, in order to exert the effect of the curing efficiently, the concrete is finished and the surface is damaged. It is said that it is preferable to start as early as possible for this young concrete if it has hardened to the extent that it does not stick.

[0005] Curing of concrete involves protecting the exposed surface of the concrete against climatic effects such as direct sunlight and heavy rain, keeping the concrete at a considerable temperature during hardening, or during hardening. It is performed for the purpose of giving sufficient moisture to the water, and as a specific method, conventionally, underwater curing, water-resistant curing, watering curing, curing with a compress or a wet musil, wet sand curing, etc. have been adopted. ing.

[0006] Particularly, in the case of cold concrete, in order to prevent frost damage of the concrete, a curing method such as covering the surface with a sheet having a high heat insulating property or heating the space surrounded by the sheet with a heater has been adopted. I have.

[0007]

However, according to the above-mentioned conventional method for curing concrete, underwater curing is suitable for a test specimen or a small-sized precast member, but it is not suitable for general concrete structures. It is difficult to adopt this method, and there is a problem that the application range of water-hardened curing is limited because a lot of labor is required for the work of installing a formwork for storing the curing water. . On the other hand, watering curing, curing with compresses or wet mullions, wet sand curing,
In any case, there is a problem that it is not easy to manage the watering work because it is necessary to frequently perform the watering work.

Further, in particular, according to the conventional curing method for concrete in cold weather, the method using a heat insulating sheet covering the concrete has a limited heat insulating effect, and the method in which the space surrounded by the sheet is heated by a heater has a problem in that However, since it tends to dry, there is a problem that it becomes necessary to spray water many times a day, for example, and the management becomes complicated.

Accordingly, the present invention has been made in view of such a conventional problem, and can be easily applied to a general concrete structure, and a concrete curing method which is easy to manage. The purpose is to provide.

Another object of the present invention is to provide a method for curing concrete, in particular, which can cure concrete in cold weather while easily maintaining a sufficient heat retaining effect.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and the gist of the present invention is to cover the exposed surface of young concrete with a fiber sheet made of a water-absorbing polymer. Another object of the present invention is to provide a method for curing concrete, comprising absorbing the water-absorbing polymer fiber sheet.

In the above description, the term "fiber sheet made of a water-absorbing polymer" refers to a sheet made of a water-absorbing polymer which is formed into fibers by performing various processes such as nonwoven fabric, spinning, and woven fabric. Various products already used as disposable diapers, sanitary products, dehumidifying filters, water retention sheets for agriculture and horticulture and the like can be appropriately modified and used.

The water-absorbing polymer constituting such a fiber sheet is, for example, a polymer obtained by crosslinking and polymerizing a polymer such as polyacrylate, polyvinyl alcohol or polyacrylamide, or a polysaccharide such as starch or cellulose. Various known polymers such as a superabsorbent polymer or a superabsorbent polymer, such as a product obtained by graft-polymerizing a polymer, can be used.

The thickness of the fiber sheet to be used can be appropriately designed in consideration of the swelling ratio of the water-absorbing polymer as a raw material, the thickness of the fiber sheet after swelling, the amount of water retention, and the like.

On the other hand, the method for curing concrete of the present invention is particularly preferably employed as a method for curing cold concrete of young age.

According to the concrete curing method of the present invention, the exposed surface of the young concrete is covered with a fiber sheet made of a water-absorbing polymer, and the water-absorbing polymer fiber sheet is sprayed with water, for example. When applied and absorbed, the water-absorbing polymer fiber sheet swells while taking in a large amount of water, and forms a layer of curing water covering the exposed surface of the concrete.

Therefore, moisture is always supplied to the exposed surface of the concrete from the water-absorbing polymer fiber sheet which swells and holds a large amount of curing water, and the moisture is held by the water-absorbing polymer fiber sheet. Since the cured water that has been separated is less likely to separate from the air and diffuse into the atmosphere, it is possible to reduce the frequency of water replenishment work, such as watering, for newly absorbing the cured water to the fiber sheet.

Further, since the water-absorbing polymer fiber sheet can be easily installed at any place while covering the exposed surface of the concrete, it can be easily applied to general concrete structures. Will be possible.

When the method for curing concrete of the present invention is applied to cold concrete in particular, for example, when the outside temperature drops and the water-absorbed polymer fiber sheet freezes, the sheet is constituted by fibers. Therefore, it freezes while taking in air to form a frozen layer having a certain heat-retaining effect as if it were snow-covered. In addition, since the water-absorbing polymer fiber sheet absorbs the curing water, the curing water does not accumulate on the exposed surface of the concrete and freeze.When the water-absorbing fiber sheet freezes, the space between the exposed surface and the fiber sheet is reduced. , A thin air layer having a heat retaining action is formed.

Therefore, due to these heat retaining effects,
It is possible to prevent freezing damage caused by freezing of young concrete.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention, ie, an embodiment, will be described below in detail with reference to the accompanying drawings. The method for curing concrete according to this embodiment is, for example, when casting concrete in the cold in order to construct a concrete structure in a cold region, while preventing the occurrence of initial stress and cracking due to drying shrinkage of the concrete, water It has been adopted for the purpose of promoting the summing action to increase the initial strength and to prevent the frost damage of concrete.

That is, according to the concrete curing method according to this embodiment, as shown in FIG. 1, if the concrete 10 is hardened to the extent that the surface thereof is not damaged after finishing the striking, The exposed surface 11 of the concrete 10 which is not covered by the mold, which is located at the top end of the concrete 10, is covered with a fiber sheet 12 made of a water-absorbing polymer.
The concrete 10 is cured by, for example, spraying water onto the surface thereof to absorb the curing water.

As the fiber sheet 12 made of a water-absorbing polymer, for example, a water-absorbing polymer obtained by crosslinking and polymerizing a polymer such as polyacrylate is subjected to various processes such as nonwoven fabric, spinning and woven fabric. It can be used in the form of a sheet, which can be used in the form of a sheet. For example, a product obtained by fiberizing sodium polyacrylate used in a water-absorbing polymer, trade name Bell Oasis (manufactured by Kanebo Corporation) Those processed into a sheet shape can be used.

In order to provide such a water-absorbing polymer fiber sheet 12 on the exposed surface 11 which is not covered by the mold, for example, the concrete nails are pressed while pressing the periphery of the fiber sheet 12 with a pressing plate. By driving, the exposed surface 11 can be covered and easily laid and fixed.

It is preferable that the water-absorbing polymer fiber sheet 12 is laid so as to cover the entire exposed surface 11 of the concrete 10, but it may be provided only in a necessary portion.

After the water-absorbing polymer fiber sheet 12 is laid on the exposed surface 11 of the concrete 10 as described above, an operation of absorbing the curing water into the fiber sheet 12 is performed. Such a fiber sheet 12 easily becomes a water-absorbing state without collecting water on the surface of the concrete 10 by absorbing rainwater caused by rainfall. For example, by performing watering work, a large amount of supplied water can be obtained. While swelling while absorbing and taking in water, a layer of curing water is easily formed on the exposed surface 11 of the concrete 10 while retaining the taken-in moisture.

Since the water-absorbing polymer forms fibers, water can be transmitted over a wide area. Therefore, even when the water supply location by watering is limited, the entire area of the laid fiber sheet 12 is cured. Water can be easily supplied.

According to the method for curing the concrete 10 of this embodiment, in which the exposed surface of the concrete 10 is covered with the water-absorbing polymer fiber sheet 12 having absorbed the curing water in this manner, for example, a temperature below the freezing point is reached. In the daytime when no water is consumed, the water-absorbent polymer fiber sheet 12 that holds a large amount of water to form a layer of curing water
The surface of the concrete 10 can be prevented from being dried by the influence of direct sunlight, wind, etc., by always supplying the moisture to the exposed surface 11 of the base material. Since the curing water is unlikely to separate and diffuse into the atmosphere, the fiber sheet 12
This eliminates the need for frequent replenishment of water by sprinkling water to newly absorb curing water.

On the other hand, at night, for example, when the outside air temperature drops to reach a temperature below the freezing point, the water-absorbing polymer fiber sheet 12 that has absorbed water freezes, but this sheet 12 is formed of fibers. Therefore, it freezes while taking in air, and forms a frozen layer 13 having a heat-retaining effect as if it were a deep snow on the surface of the concrete 10 having a young age. When the fiber sheet 12 that has absorbed water freezes, a thin air layer 14 having a heat-retaining effect is formed between the exposed surface 11 of the concrete 10 and the fiber sheet 12, and these heat-retaining effects are obtained. Thereby, freezing of the young concrete 10 is prevented and freezing damage is avoided.

In the above embodiment, the case where the top end of the cold concrete 10 of the young age is covered with the water-absorbing polymer fiber sheet 12 and cured is described.
The present invention is not limited to the embodiments of the embodiments, but can be variously modified and adopted within the scope of the configuration described in each claim. For example, the curing method of the present invention can be applied not only to cold concrete but also to general concrete structures for the purpose of preventing the occurrence of initial stress and cracks due to drying. By appropriately attaching the fiber sheet, it can be adopted as a curing method not only for the top end portion of the concrete structure but also for the exposed surface of other portions.

[0031]

As described above in detail, according to the concrete curing method of the present invention, the exposed surface of the concrete of the young age is covered with the fiber sheet made of the water-absorbing polymer, It consists of absorbing water from the molecular fiber sheet, so that moisture is always supplied to the exposed surface of the concrete from the layer of curing water by the water-absorbing polymer fiber sheet that has taken in a large amount of water. The curing water held by the sheet is less likely to separate from it and diffuse into the atmosphere, and the work of attaching the water-absorbing polymer fiber sheet is easy. Therefore, the method for curing concrete of the present invention can be easily applied to general concrete structures, and at the same time, the frequency of water replenishment work by water sprinkling or the like can be reduced to facilitate the management. Can be.

When used as a method for curing concrete in cold weather, the water-absorbent polymer fiber sheet freezes while taking in air to form a frozen layer having a heat-retaining effect, such as snow-covered snow. Since a thin air layer having a heat-retaining effect is formed between the fiber sheet and the fiber sheet, freezing of the young concrete is easily prevented by these heat-retaining effects.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating a curing method according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 concrete 11 exposed surface 12 water-absorbing polymer fiber sheet 13 frozen layer 14 air layer

Claims (2)

[Claims] 1. A method for curing concrete, comprising: covering an exposed surface of a concrete of a young age with a fiber sheet made of a water-absorbing polymer and absorbing the water with the water-absorbing polymer fiber sheet. 2. The method for curing concrete according to claim 1, wherein the concrete is cold concrete.