JP3680680B2 - Water insulation sheet for concrete placement - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a water-retaining insulation sheet for concrete placement, and more particularly, to a water retention insulation sheet for concrete placement capable of absorbing excess water immediately after concrete placement and replenishing water after hardening has started. .
[0002]
[Prior art]
In order to increase the durability of concrete, preventing the neutralization of concrete is one of the important factors. Neutralization occurs when carbon dioxide in the air enters the concrete and combines with the alkali components contained in the concrete. In order to prevent this neutralization, it is effective to prevent the intrusion of carbon dioxide gas by discharging excess mixing water that causes voids in the concrete surface and densifying the concrete.
[0003]
As a method of discharging surplus water at the time of placing concrete, for example, Japanese Patent Laid-Open No. 6-272375 includes a water-permeable sheet such as a polyester sheet and a cotton cloth or a polyester / cotton mixed cloth on a concrete placing surface of a mold. Laminating a water retention sheet is disclosed. According to this method, excess water in the concrete is absorbed by the water retention sheet, and moisture that cannot be absorbed by the water retention sheet is discharged to the outside through the drainage sheet.
[0004]
By the way, after the concrete is placed, after hardening progresses and the hydration reaction stops, gaps due to hydration shrinkage and capillary voids due to unhydration remain. In order to prevent the generation of gaps and voids remaining after such a hydration reaction, it is effective to supply moisture to the concrete when the concrete has hardened to some extent.
[0005]
In addition, after the concrete is placed, the internal temperature rises due to the hydration heat of the concrete. Therefore, at the early stage of concrete age, if the surface temperature is lowered before sufficient strength is developed, there is a risk of temperature cracks occurring on the concrete surface due to the temperature difference from the concrete interior. It is also important to keep the concrete surface warm in order to prevent such temperature cracks.
[0006]
[Problems to be solved by the invention]
However, in the technique disclosed in the above publication, although the water stored in the water retention sheet is supplied to the concrete that has started to harden, the supply amount is limited by the water retention capacity of the cotton cloth or the mixed cloth constituting the water retention sheet. Will be. For this reason, the above method cannot supply a sufficient amount of moisture to the concrete. In this respect, the above-described method is not suitable for preventing the generation of gaps due to hydration shrinkage and inter-capillary voids due to unhydration. In addition, cloth and polyester sheets are used as the water retaining sheet and drainage sheet, and no consideration is given to keeping the concrete surface warm and preventing temperature cracking.
[0007]
The present invention has been made in view of the above points, and can absorb excess mixing water at the time of pouring the concrete to increase the density of the concrete and supply a sufficient amount of moisture to the concrete after the start of curing. A water-retaining and heat-insulating sheet for concrete placement that prevents the occurrence of voids and gaps due to the termination of the hydration reaction, and also prevents the occurrence of temperature cracks by exhibiting excellent heat retention on the concrete surface. The purpose is to provide.
[0008]
[Means for solving the problem]
The object is to provide a water-retaining and heat-insulating sheet that is used by being attached to the inner surface of a formwork when casting concrete, and a plurality of independent cavities provided inside the sheet, A first communication passage that is provided in the vicinity of the lower end portion of the steel plate and opens on the surface on the side where the concrete is placed, a rear groove provided on the surface on the side that is attached to the mold, and in the vicinity of the upper end portion of the cavity And a second communication passage that communicates with the rear groove, and moisture in the concrete flows into the cavity through the first communication passage, and when the cavity is filled with water, Water is discharged to the back groove through the second communication passage, and when the concrete is water-absorbing, the water in the cavity flows into the concrete through the first communication passage. Water retention It is achieved by the water retaining insulation sheet which functions as a.
[0009]
In the present invention, the first communication passage is provided in the vicinity of the lower end portion of the cavity provided in the seat, and opens to the surface on the side where the concrete is placed . For this reason, excess water contained in the placed concrete flows into the cavity via the first communication path due to the water pressure. In that case, the air which existed in the cavity is discharged | emitted from a back surface groove | channel through the 2nd communicating path provided in the upper end part vicinity of the cavity . Moreover, even after the cavity is filled with water, the water can flow into the cavity from the concrete by overflowing the back channel through the second communication path. On the other hand, when the concrete is hardened to some extent, the water accumulated in the cavity flows out to the concrete side, and water is supplied to the concrete. At this time, the amount of water that can be replenished to the concrete is an amount corresponding to the volume of the cavity, so that a sufficient amount of water to be supplied to the concrete can be secured by appropriately designing the volume of the cavity. Moreover, the heat insulation property of the air in the cavity can keep the concrete surface warm.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 and FIG. 2 are a perspective view and a cross-sectional view, respectively, showing a state in which a water-retaining and heat-insulating sheet 10 according to an embodiment of the present invention is attached to a concrete casting mold 12. The water retaining heat insulating sheet 10 is attached to the inner wall surface of the mold 12 with, for example, an adhesive, and concrete is placed in this state. In addition, in FIG. 2, the motion of the water at the time of the surplus water in concrete being absorbed by the water retention heat insulation sheet 10 is shown by the arrow.
[0011]
The water retention heat insulating sheet 10 includes a plurality of water retention chambers 14 which are cavities independent of each other. In addition, a plurality of first communication holes 16 are opened on the surface of the water retaining heat insulating sheet 10 (surface on the concrete placement side). The first communication holes 16 communicate with the vicinity of the lower end of the water retention chamber 14, respectively. In addition, a plurality of back surface grooves 18 extending in the vertical direction are provided on the back surface (surface on the side attached to the mold 12) of the water retaining heat insulating sheet 10. The rear groove 18 serves as a passage that allows the water retention chamber 14 to communicate with the atmosphere in a state where the water retention heat insulating sheet 10 is attached to the mold 12. Each of the water retention chambers 14 communicates with any one of the rear grooves 18 through a second communication hole 20 provided in the vicinity of the upper end portion thereof.
[0012]
According to the above configuration, immediately after placing the concrete, excess mixing water contained in the concrete flows into the water retention chamber 14 through the first communication hole 16 due to the water pressure. In this case, the air that was present in the water retention chamber 14 is pushed out by the inflowing water and is discharged from the back surface groove 18 to the outside through the second communication hole 20. In addition, even after the water retention chamber 14 is filled with water, the water overflows from the second communication hole 20 and is discharged to the outside through the back groove 18 so that moisture can be continuously absorbed from the concrete. is there.
[0013]
On the other hand, when the cast concrete hardens, the concrete becomes water-absorbing, and the water accumulated in the water retention chamber 14 flows out through the first communication hole 16 to the concrete side. That is, the excess mixing water absorbed immediately after placing the concrete is supplied to the concrete as water necessary for continuing the hydration reaction.
[0014]
Moreover, since the water content of the water retention chamber 14 can be replenished to the concrete from the water retention insulation sheet 10, the hydration reaction from the water retention insulation sheet 10 to the concrete can be performed by appropriately designing the volume of the water retention chamber 14. A sufficient amount of moisture can be supplied to continue. That is, since the water supply capability of the water retention heat insulating sheet 10 can be adjusted by the volume of the water retention chamber 14, a sufficient amount of moisture relative to the concrete compared to the case where a water absorbent material such as cotton cloth or mixed cloth is used as in the prior art. Can be replenished.
[0015]
Therefore, according to the water retaining and heat insulating sheet 10 of the present embodiment, the concrete surface can be densified by removing excess water, and at the gaps and unhydrated portions accompanying hydration shrinkage by promoting the hydration reaction. Generation of capillary voids can be suppressed. For this reason, the penetration | invasion of the carbon dioxide gas from the air | atmosphere into concrete can be blocked | prevented more reliably, neutralization of concrete can be prevented, and, thereby, durability of concrete can be improved. Moreover, the strength of the concrete can be increased by suppressing the generation of gaps and voids in the concrete.
[0016]
Furthermore, when moisture is supplied from the water retaining heat insulating sheet 10 to the concrete, the water retaining chamber 14 becomes hollow. Due to the heat insulating action of the air in the water retention chamber 14, the water retention heat insulating sheet 10 has high heat retention. For this reason, it is possible to keep the surface of the concrete at the early stage of the material age warm and to prevent the occurrence of temperature cracks due to the temperature difference from the inside of the concrete, thereby further improving the durability and strength of the concrete. it can.
[0017]
Moreover, the role which hold | maintains the formwork 12 can also be given to the water retention heat insulation sheet 10 by enlarging the thickness of the water retention heat insulation sheet 10 and improving the rigidity. In this case, it is possible to simplify or omit the inner end thickness / outer end thickness holding the mold 12 to save labor in the mold installation process.
[0018]
Furthermore, by forming the surface shape of the water retaining heat insulating sheet 10 in a shape according to the desired finish surface property of concrete, for example, a tile joint shape is obtained and good adhesion to the base mortar is obtained. Therefore, it is possible to easily realize an uneven launch for the purpose.
[0019]
【The invention's effect】
As described above, according to the water retaining and heat insulating sheet according to the present invention, moisture can be absorbed from concrete and stored in the cavity, and moisture stored in the cavity can be supplied to the concrete. For this reason, it is possible to absorb the excess mixing water immediately after placing the concrete to make the concrete surface dense, and after the concrete starts hardening, water is supplied to the concrete to generate gaps and voids. Can be prevented. In this case, it is possible to ensure a sufficient amount of water supply to the concrete by appropriately designing the volume of the cavity. Therefore, according to the present invention, it is possible to improve the durability of the concrete and to increase the strength of the concrete by preventing the carbon dioxide gas from entering the concrete and preventing the neutralization. Furthermore, the surface of the concrete can be kept warm by the heat insulating action of the air inside the water insulating sheet. For this reason, it is possible to prevent temperature cracks on the concrete surface, thereby further improving the durability and strength of the concrete.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a state in which a water retaining and heat insulating sheet according to an embodiment of the present invention is attached to a mold.
FIG. 2 is a cross-sectional view of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Water retention heat insulation sheet 12 Form 14 Water retention chamber 16 1st communication path 18 Back surface groove | channel 20 2nd communication path

Claims (1)

It is a water-retaining and heat-insulating sheet that is used by attaching to the inner surface of the formwork when placing concrete,
A plurality of independent cavities provided inside the sheet, a first communication path provided in the vicinity of a lower end portion of the cavity and opened on a surface on which concrete is placed , and a side attached to the formwork A rear groove provided on the surface of the cavity and a second communication path provided in the vicinity of the upper end portion of the cavity and communicating with the rear groove, and moisture in the concrete passes through the first communication path to form the cavity. When the cavity is filled with water, the water in the cavity is discharged to the back groove through the second communication passage, and when the concrete is water-absorbing, the water in the cavity is The water retention heat insulating sheet, wherein the cavity functions as a water retention chamber by flowing into the concrete side through the first communication path .

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