JP2009235894A - Concrete curing method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete curing system and method having movable water spray equipment as a measure method for preventing cracking of concrete constructed on a continuum of a tunnel or box culvert. <P>SOLUTION: A support member is assembled at a position separated from the concrete surface of a body structure by 100-300 mm. Wheels are attached to the leg parts of the support member. Water spray tools 3 are installed, and the support member is covered with a waterproof sheet 2. The concrete curing system is installed immediately after removing concrete placing forms, and water spraying is started and continued for 24-72 hours. After completing the water spraying, the concrete curing system can move in this state by one span of concrete placing. A device warming water to adjust water spray temperature can be mounted. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a concrete curing equipment and method for preventing cracking of newly-installed concrete constructed with a continuous body such as a tunnel or a box culvert.

  As for concrete curing methods, mat curing, watering curing, flooded curing, mushiro curing, sheet curing, curing agent spraying and the like are generally performed. The general concrete structure is carried out for 72 to 168 hours after the concrete casting form is removed to prevent cracking of the concrete. However, for structures constructed with continuums such as tunnel secondary lining concrete and box culverts, the concrete is cured because the space inside the mine is used for material loading and unloading and excavation of sediments and rocks after removing the formwork. Is currently not done. As a result, these concretes are cracked. These cracks are repaired with an epoxy resin or the like because the crack width increases at the time of construction delivery, and this process and cost are required to be large. If the crack width is 0.2 mm or less, the completed delivery is performed without carrying out repairs, and the crack progresses and the crack width increases, causing peeling and peeling of the concrete.

JP 2001-248398 A (reference document at the time of examination) Japanese Unexamined Patent Publication No. 2000-73696 (reference document at the time of trial)

As a method for preventing cracking of the tunnel secondary lining concrete and box culvert described above, there are the following problems in performing concrete curing.
The “I” mine must be opened as a passageway during concrete curing.
“B” concrete curing equipment must be easy to assemble and remove.
“C” The covering position from the concrete surface must be within 400 mm.
"D" Water sprinkled should not be dropped into a passage in the mine.
The “e” curing cover must be able to keep the concrete surface moist.
“F” In winter, it is necessary to be able to adjust the watering temperature.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a mobile concrete curing equipment and method as a method for preventing cracking of tunnel secondary lining concrete and box culvert. .

In order to achieve the above object, the concrete curing equipment / method of the present invention assembles a support member at a position 100 to 300 mm away from the concrete surface in the tunnel ring direction immediately after removing the concrete casting formwork. Attach the wheel to the leg. Next, the supporting member is provided with watering equipment, the entire surface of the supporting member is covered with a waterproof sheet on the concrete surface side, water spraying is started by a sprinkler system, and water is continuously sprinkled for 24 to 72 hours to prevent concrete cracking. It is. Since this equipment has mobile wheels, it can be moved to the next one span in this state.
The facility of the present invention can also be equipped with a device for warming water for adjusting the watering temperature.
[Measures against initial cracks in concrete]

In concrete, water and cement undergo a hydration reaction, and the heat of hydration is generated, so that hardening starts and reaches the required strength at the age of 28 days. The heat of hydration occurs at the very early stage of the hardening process of concrete, resulting in a temperature difference between the concrete surface and the central part. Compared with the temperature stress due to this temperature difference and the tensile stress of the concrete itself, Cracks occur when the tensile stress of concrete is small. In this very early stage, if the concrete surface is not exposed to the outside air, and if the concrete surface is not dried by spraying water, the temperature difference between the concrete surface and the central portion is reduced, and the probability of occurrence of cracks is reduced.
Further, when the concrete surface becomes dry, cracks due to drying occur. Water is sprayed on the concrete surface to prevent this crack.
These watering curings are carried out on general concrete structures. However, the structure which continues construction with continuous bodies, such as a tunnel secondary lining concrete and a box culvert, has not been implemented as a curing until now. For this reason, cracks are generated in the concrete. The present invention is based on this principle, “Concrete is cured”. Sprinkler water is sprayed for a very initial period of time so that the concrete surface is not dried, and water is sprinkled while rotating at each location. This prevents cracking.
[Equipment of the present invention]

The equipment of the present invention forms a frame with a support member in a space of 100 to 300 mm from the lining concrete surface in the tunnel mine. If this interval is narrower than 100 millimeters, the installation interval of the watering device becomes narrow, and a large amount of material costs for the watering device are required, which is uneconomical. Further, if the interval is increased from 300 mm, the vehicle limit of 400 mm cannot be observed from the concrete surface necessary for a work vehicle or the like to pass through the tunnel mine. Sprinklers for watering are provided on the frame at intervals of 1 to 3 m. Cover the concrete side of the frame with a waterproof sheet. (The tread in the tunnel direction at each tunnel placement is also covered with a waterproof sheet.) The humidity in this sheet is maintained at 90% or more by the heat of hydration of the cement, and further, no wind enters this space. The water sprayed on the concrete surface flows down the waterproof sheet and flows down to the bottom. The length per time of the present invention can be adjusted according to the former length of the tunnel lining concrete, and the length can be easily adjusted. In addition, the correspondence of the curved portion is possible by matching the position of each supporting member to the curved line in the tunnel ring method.
A rail-type wheel or a tire-type wheel is attached to the lower part of the support member, and equipment that can be easily moved for each span is provided.
[Watering time]

図１にＡ試験およびＢ試験の本発明方法とトンネル二次覆工コンクリートひび割れ長さ合計の関係図を示す。
［発明の効果］ As the water to be sprinkled, any industrial water, underground water, tap water or the like can be applied as long as it does not adversely affect the quality of concrete. Moreover, when the concrete temperature is low in winter construction and the temperature of water for spraying is low, it can also have the equipment which makes this watering temperature 10-20 degreeC warm water.
Table 1 shows the relationship between the watering time and the total crack length ratio in the actual tunnel. As is apparent from this test result, compared to 100% when there is no conventional curing time, the watering time is 24 hours and the total crack length is about 20%, 11% at 48 hours, 4% at 72 hours, 96%. 4% in time. Another test result In FIG. 1, no cracks occurred in 24 hours 10%, 48 hours 3%, 72 hours and 96 hours.
The normal tunnel secondary lining concrete placement cycle is once every two days. Based on this cycle, after placing the secondary lining concrete, it is preferable to remove the form the next day, immediately install the equipment of the present invention, start watering, and continue for 72 hours.
The amount of water spray is preferably 0.1 to 5 liters / minute / location while rotating by a sprinkler system.

FIG. 1 shows the relationship between the method of the present invention for the A test and the B test and the total crack length of the tunnel secondary lining concrete.
[The invention's effect]

Since the mobile curing method of the present invention having a watering facility is as described above, the following effects can be obtained.
It can be carried out without affecting other constructions because it is a “b” mobile type that can prevent cracking of concrete that is constructed with a continuous body such as “I” tunnel or box culvert and can secure space in the tunnel mine.
“C” Assembling and removing are simple and easy, so the time and cost are reduced.
“D” members and instruments can be used several times for different construction, and there is nothing to be discarded, making it an environmentally friendly method.
"E" The construction period is shorter than conventional crack repair, and the cost can be reduced.

Relationship diagram between the method of the present invention of A test and B test and total crack length of tunnel secondary lining concrete Facility diagram of the present invention Example of tunnel secondary lining concrete Example of box culvert concrete

Embodiments of the present invention will be described below with reference to the drawings.
[Supporting members]

The supporting member 1a in the tunnel ring direction may be H steel, aluminum light metal, or the like, and is processed at a factory in accordance with the shape of the tunnel structure and is carried to the site. The supporting member 1b in the tunnel direction may also be H steel or aluminum light metal. Install at a position 100 to 300 mm away from the concrete surface. The length in one tunnel direction is adjusted with a steel rod or the like so that it can be adjusted at any time according to the support member in the tunnel ring direction.
[Waterproof sheet]

The waterproof sheet 2 does not have to drop the sprinkled water into the tunnel tunnel, and this material may be any of commonly used polyethylene sheet (tunnel waterproof sheet), ordinary olefin-based chemical synthetic sheet, rubber sheet, and the like. .
[Watering equipment]

For the watering device 3, the sprinkler system is most suitable because it can uniformly spray water on the concrete surface. It is preferable to rotate 360 degrees. The amount of water spray varies depending on the concrete thickness and concrete temperature, but when the concrete thickness is 300 mm and the concrete temperature is as low as 10 ° C, the range is 0.1 to 2 liters / minute, and the concrete thickness is 500 mm. When the concrete temperature is as high as 30 ° C., the range of 1 to 5 liters / minute is preferable.
[Mobile wheel]

The wheel 4 for moving is a steel material type round shape matched to the rail, and the diameter is preferably 10 to 15 cm. In the case of a tire type, a rubber type and a diameter of 10 to 15 cm is suitable similarly to the rail type.
Embodiments of the present invention will be described below with reference to the drawings.
[Crack countermeasure effect by the method of the present invention]

  FIG. 1 shows an example of a crack countermeasure effect by the method of the present invention. In the tunnel secondary lining concrete, it was revealed that the cracking of the tunnel secondary lining concrete was extremely reduced by performing the watering time from 24 hours to 96 hours by the method of the present invention. The watering time was a result suitable for 24 to 72 hours.

Embodiments of the present invention will be described below with reference to the drawings.
[Example of installing on tunnel secondary lining concrete]

Inside the tunnel secondary lining concrete 5, the support member 1a and the support member 1b are assembled, and the wheel 4a is attached to the lower side. Next, the watering device 3 is installed on the support member. Thereafter, it is covered with a waterproof sheet 2. Watering starts immediately after placing concrete and removing the formwork. The watering time lasts from 24 hours to 72 hours.
[Example of installation in a box culvert]

  Inside the box culvert concrete 6, the support member 1a and the support member 1b are assembled, and the wheel 4b is attached to the lower side. Next, the watering device 3 is installed on the support member. Thereafter, it is covered with a waterproof sheet 2. Watering starts immediately after placing concrete and removing the formwork. The watering time lasts from 24 hours to 72 hours.

DESCRIPTION OF SYMBOLS 1 ... Supporting member 2 ... Waterproof sheet 3 ... Watering device 4 ... Wheel 5 ... Tunnel secondary lining concrete 6 ... Box culvert concrete

Claims (1)

In concrete constructed with a continuous body such as a tunnel or box culvert,
Concrete hitting設型frame after removal, immediately assembled supporting coercive member at a distance from 100 to 300 mm from the concrete surface, mounting the wheel on its legs, and installed sprinkler systems in this支保member, the same支保member covering the concrete surface side entire surface sheet, 24 hours to 72 hours of continuous water spray to be the start of the watering concrete surface, and curing method of the concrete, characterized in that the equipment can be moved.

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