JP2010209629A - Concrete curing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete curing method which realizes concrete curing which does not produce any thermal shock by short-term curing at low cost. <P>SOLUTION: An airbag 11 which can adjust its thickness by the infusion/discharge of internal air is used as a heat-insulating coating material which covers the surface of a concrete skeleton 10 after the pouring of concrete. The surface of the concrete skeleton 10 is covered with the airbag 11, and curing is performed while gradually reducing heat insulating performance by gradually discharging the air in the airbag 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a concrete curing method for curing a concrete frame classified mainly as mass concrete so as not to cause an internally constrained temperature crack.

  In general, slab concrete having a thickness of 80 cm or more and spreading in the horizontal direction is classified as mass concrete, and is susceptible to temperature cracking due to heat of hydration reaction during concrete hardening. This is because a large temperature difference is generated in the cross section of the concrete body due to the temperature difference between the inside of the concrete body and the outside air, and the temperature gradient is increased, and irregular cracks are particularly likely to occur on the surface portion.

  This phenomenon is known as an internally constrained temperature crack, and the most effective countermeasure is to reduce the temperature difference between the inside and the surface of the concrete frame. Therefore, in general, air is contained, the surface of the concrete frame is covered with a sheet of heat-insulating air bag or glass wool, etc., and heat is prevented by preventing heat dissipation from the concrete surface. Reduction and suppression of internally constrained temperature cracks have been implemented (for example, Patent Document 1).

Also, as a method of curing while keeping the temperature gradient in the concrete body small, warm air or hot water is allowed to flow in the formwork or the coating material on the surface of the concrete body so that the surface temperature of the concrete body is close to the center. There is a method of curing (for example, Patent Documents 2 and 3).
JP 2005-90146 A JP 2000-6128 A JP-A-10-227127

  In the conventional method described above, a certain heat retaining effect can be obtained by covering the surface of the concrete frame, and the temperature difference between the inside and the surface portion can be reduced and temperature cracking can be suppressed. However, in the curing that keeps the concrete warm only by covering with a specific material, it takes time to decrease the internal temperature because the surface is covered and kept warm, and the temperature difference between the internal temperature and the surface temperature causes temperature cracks. It takes a long curing period to reach the value required to prevent it.

  However, due to requests for shortening the construction period and weather / sea conditions, it may be necessary to stop the thermal curing without waiting for the internal temperature to drop sufficiently, but if the coating for curing is removed early, As shown in the figure, the temperature of the surface suddenly drops and the temperature difference between the inside and the surface becomes larger than the case where the temperature is not increased from the beginning (shown in FIG. 3) because the internal temperature has increased due to the temperature increase. There was a problem that cracking was likely to occur (called thermal shock).

  In addition, the above-described method of warming and curing using warm air or warm water can control the ambient temperature with a temperature sensor and warm air, but there is a problem that the cost increases.

  In view of such a conventional problem, the present invention has been made for the purpose of providing a concrete curing method in which the above-described concrete curing without thermal shock can be performed at a low cost by a short-term curing.

  The feature of the concrete curing method according to claim 1, which solves the conventional problems as described above and achieves the intended purpose, is to maintain heat by covering the surface of the concrete frame after placing the concrete with a heat insulating covering material. In the concrete curing method for preventing cracking during solidification by reducing the temperature gradient between the inside and the surface of the concrete casing, an air bag whose thickness can be adjusted by pouring and discharging the inside air is used as the covering material. Then, the concrete body surface after the concrete placement is covered with the air bag, and the air inside the air bag is gradually discharged to cure while gradually reducing the heat insulating property of the air bag.

  According to a second aspect of the present invention, a flow rate adjustment valve is provided in the air injection / discharge path of the airbag, and the air in the airbag is gradually discharged by adjusting the degree of opening of the flow rate adjustment valve. The purpose is to adjust the air discharge amount.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect, the air injection / exhaust passage leading to the airbag is communicated with the intake / exhaust pump and the amount of air discharged to the air injection / exhaust passage is measured. There is provided a flow meter capable of controlling the discharge amount of air in the airbag by adjusting the degree of opening of the flow rate adjusting valve while measuring the discharge amount by the flow meter.

  According to a fourth aspect of the present invention, in addition to the structure of any one of the first, second, and third aspects, a plurality of the airbags are used, and the air in the airbag is changed depending on the portion of the concrete frame. It is to change the discharge speed.

  As described above, in the concrete curing method according to the present invention, an air bag whose thickness can be adjusted by pouring internal air is used as a heat insulating coating material (heat insulation coating material), and the concrete is used in the air bag. Covering the surface of the concrete frame after placing and gradually evacuating the air in the airbag to gradually reduce the heat insulation of the airbag, thereby gradually releasing the air inside the airbag. As a result of the thickness phenomenon, the heat retention effect gradually decreases, and the surface temperature gradually approaches the outside air temperature while the temperature difference between the inside and the surface of the concrete frame is small. From the standpoint of economy and economy, the interior temperature can be kept close to the outside temperature while reducing the temperature difference between the inside of the concrete frame and the surface without significantly increasing the thermal insulation. A bundle type temperature cracks can be suppressed.

  Further, a flow rate adjustment valve is provided in the air injection / discharge path of the airbag, and the air discharge amount for gradually discharging the air in the airbag is adjusted by adjusting the opening degree of the flow rate adjustment valve. Thus, the desired effect can be obtained by the airbag having a simple structure.

  In addition, an air injection / discharge path communicating with the airbag is connected to a flow rate control valve, and a flow meter capable of measuring the amount of air discharged to the air injection / discharge path is provided, and the discharge amount is measured by the flow meter. However, by controlling the amount of air discharged from the airbag by adjusting the degree of opening of the flow rate adjusting valve, it is possible to quantitatively manage the heat insulation effect (heat retention effect).

  Furthermore, by using a plurality of airbags and changing the air discharge speed in the airbag according to the portion of the concrete casing, an appropriate curing effect can be obtained according to the temperature change of the portion of the concrete casing.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows an outline of an apparatus used in the method of the present invention. In the figure, reference numeral 10 denotes a concrete frame to be cured. After the concrete casing 10 is placed in the concrete, the surface is covered with an airbag 11 which is a covering material. The air bag 11 has a space 11c between the front and back airtight sheet materials 11a and 11b that can be filled with air, and the overall thickness changes by changing the amount of air in the space 11c. This makes it possible to adjust the degree of thermal insulation.

  The airbag 11 is provided with a flow rate control valve 12 that can discharge the filled air in a fixed amount in a pouring / exhausting path for filling the air in the internal space 11c. The flow rate adjusting valve 12 can be a needle valve whose opening is adjusted by the insertion depth of the needle or a hand-operated cock whose opening is adjustable.

  Moreover, the sheet material which comprises the airbag 11 uses the thing of synthetic resin materials, such as polyethylene, for example, The size of the airbag 11 is 2 m long x horizontal so that it can lay by manual work easily, for example. It is formed in a size of about 1 m × thickness 0.1 m, and this is used by arranging the required number according to the width of the surface of the concrete frame 10. In addition, the air bag 11 is made of a rubber-like self-shrinkable material and is formed so that the thickness direction is deflated by its own elasticity when it is not filled with air, and air is press-fitted. It is also possible to use one that bulges in the thickness direction and opens the flow length adjustment valve so that air is gradually discharged by the self-contracting force.

  The airbag 11 is laid without a gap on the surface of the concrete frame 10 after being placed in a state where the air is not filled therein. Thereafter, each air bag 11 is filled with air using an air compressor. The opening degree of the flow control valve 12 is adjusted to a preset opening degree. In this way, curing is performed for a predetermined time (days). During this time, the air in the airbag 11 is gradually removed, and the heat insulation is gradually lowered as the thickness decreases.

  Also, depending on the location of the concrete housing 10, for example, there is a change in the internal temperature at the central portion and the peripheral portion of the surface of the concrete housing, so the change in the heat insulation performance for each airbag 11 is adjusted accordingly. If necessary, it can be dealt with by adjusting the degree of opening of the flow rate regulating valve for each airbag 11 according to the body part.

  In the above-described embodiment, the air in the airbag 11 is naturally reduced, but in addition to this, the air in the airbag 11 may be forcibly reduced. As shown in FIG. 2, an individual pouring / removing path 15 is connected to the outlet side of the flow rate adjusting valve 12 of each air bag 11, and these are connected to one common pouring / discharging path 16, to which a flow rate adjusting valve 17 is attached. This common injection / discharge path 16 is communicated with the injection / exhaust pump 18, whereby the air in the airbag 11 can be forcedly discharged / discharged. In addition, you may provide the flow meter 19 in each individual pouring / removing path 15, and can manage quantitatively the heat insulation performance by this.

  In addition, although not shown in the figure, a temperature sensor is installed in each part of the concrete frame, and the air discharge amount of each airbag is adjusted while measuring the internal temperature and the surface temperature for each part. As a result, more advanced temperature management becomes possible.

  3, 4, and 5, the internal temperature and the surface temperature of the concrete frame in the case where the thermal insulation coating curing is not performed, the curing using the conventional thermal insulation coating material is performed, and the curing according to the present invention are performed. It shows changes over time.

  FIG. 3 shows the temperature change when heat insulation coating curing is not performed. In this case, the surface temperature rises due to heat of hydration, while the internal temperature is cooled by the outside air temperature, so the difference is large.

  FIG. 4 shows the temperature change when the conventional thermal insulation coating material is cured to reduce the temperature difference between the surface and the interior in FIG. Yes. In this conventional curing method, although the temperature difference is reduced before the removal, a thermal shock occurs in which the surface temperature is rapidly cooled by the outside air temperature after about 2 days after the removal. Thereby, a temperature difference becomes larger than the case where heat insulation coating curing is not performed.

  FIG. 5 shows that the airbag according to the present invention was used for curing while gradually removing the air in the airbag, and controlling the exhaustion of the air in the airbag up to the age of 7 days to finish. Shows the temperature change when removed. In this example of the present invention, the temperature dropped smoothly to a temperature close to the outside air temperature by 7 days of age, and no thermal shock occurred after the airbag was removed on the 7th day of age.

It is sectional drawing which shows the outline of an example of the apparatus used for the concrete curing method which concerns on this invention. It is sectional drawing which shows the outline of the other example of the apparatus used for the concrete curing method which concerns on this invention. It is a graph which shows the temperature change at the time of not carrying out concrete curing. It is a graph which shows the temperature change in the concrete curing using the conventional heat insulation coating material. It is a graph which shows the temperature change in the concrete curing by the method of this invention.

DESCRIPTION OF SYMBOLS 10 Concrete frame 11 Air bag 11a, 11b Airtight sheet | seat material 11c Space 12 Flow control valve 15 Individual pouring / discharging path 16 Common pouring / discharging path 17 Flow regulating valve 16 Common pouring / discharging path 18 Pouring pump 19 Flow meter

Claims (4)

  In the concrete curing method, the surface of the concrete body after placing the concrete is kept warm by covering the surface with a heat-insulating coating material, and cracking during solidification is prevented by reducing the temperature gradient between the inside and the surface of the concrete body. By using an air bag whose thickness can be adjusted by pouring and discharging internal air as a covering material, covering the concrete housing surface after the concrete placement with the air bag, and gradually discharging the air in the air bag A concrete curing method characterized by curing while gradually decreasing the heat insulating property of the airbag.   The flow rate adjusting valve is provided in the air injection / discharge path of the airbag, and the air discharge amount for gradually discharging the air in the airbag is adjusted by adjusting the opening degree of the flow rate adjusting valve. Concrete curing method described in 1.   The air injection / exhaust passage leading to the airbag is connected to an injection / exhaust pump, and a flow meter capable of measuring the amount of air discharged to the air injection / exhaust passage is provided, while the discharge amount is measured by the flow meter The concrete curing method according to claim 2, wherein the discharge amount of air in the airbag is controlled by adjusting an opening degree of the flow regulating valve.   The concrete curing method according to any one of claims 1, 2, and 3, wherein a plurality of the airbags are used, and an air discharge speed in the airbag is changed according to a portion of the concrete frame.

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