JP2020147989A - Wet curing method for concrete - Google Patents

Abstract

To provide a wet curing method for concrete capable of achieving mist spraying efficiency through spraying mist to a wider area from a nozzle and improving adhesion efficiency of the mist on a concrete surface when performing wet curing by spraying mist water on the concrete surface.SOLUTION: Arranging charging electrodes 32, 32 adjacent to a spray port of a spray nozzle 31 and charging water particles to be sprayed positive or negative make spraying area wider using repulsive force between charged water particles when performing wet curing by spraying mist water on the concrete surface from the spray nozzle 31 after formwork removal. Preferably, adhesion on the concrete surface using Coulomb attraction force may be improved through oppositely charging the water particles to be sprayed to a charged surface of the concrete.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for efficiently moistening and curing concrete after demolding in the construction of underground structures such as tunnels, culverts, and underpasses.

Conventionally, for example, in mountain tunnel construction, when placing lining concrete, in order to ensure the quality of concrete and maintain durability for a long period of time, after removing the centre, sufficient wet curing is performed. It is important to promote the hydration reaction. This also applies to the construction of underground structures such as culverts and underpasses.

Sprinkling curing has long been adopted as one of the curing methods for lining concrete. For example, Patent Document 1 below includes a fluid supply pipe having a plurality of fluid outlets for blowing a fluid onto a lining concrete formed along the longitudinal direction of the tunnel on the inner circumference of the tunnel, and each fluid in the fluid supply pipe. A lining concrete curing device in a tunnel provided with a fluid recovery tray for recovering the fluid exiting the outlet is disclosed.

However, in the case of the lining concrete curing device, there are problems that a large amount of equipment cost and construction time are required, and a large amount of water is required. Therefore, some lining concrete curing devices have been proposed in which water is adhered to the concrete surface by atomizing the sprinkled water and the recovery facility for the sprinkled water is eliminated.

Specifically, in Patent Document 2 below, in a tunnel lining concrete curing device for curing by spraying water on the cast tunnel lining concrete, a spray mechanism for spraying atomized water on the tunnel lining concrete and the spray mechanism. It has a moving mechanism in which a spraying mechanism is movably provided in the tunnel, and the spraying mechanism and the moving mechanism can move in the tunnel while spraying a predetermined amount of the mist-like water on the surface of the tunnel lining concrete. A curing device for tunnel lining concrete configured as described above is disclosed.

Further, in Patent Document 3 below, concrete used in tunnel lining work for covering the inner wall surface of a tunnel with concrete and placed in the space between a formwork for lining moving in the tunnel and the inner wall surface of the tunnel. A wet curing device for lining concrete that moistens and cures the concrete surface so as to prevent cracks from occurring on the surface of the hardened lining concrete after the hardening of the concrete. The track has a track extending rearward, a moving body movable along the track, and a spraying device installed on the moving body and spraying a spray liquid toward the lining concrete. A wet curing device for lining concrete, which is movably supported by a support material added in the traveling direction as the formwork progresses, is disclosed.

JP-A-2009-155820 Japanese Unexamined Patent Publication No. 2006-89995 JP-A-2009-108612

By spraying it on the concrete surface as mist-like water (hereinafter, also referred to as mist), an appropriate amount of water adheres to the lining concrete surface, and a part of it floats in the air to keep the surrounding environment at an appropriate temperature and humidity. It will be possible. In addition, since the curing water does not fall as water droplets along the concrete wall surface, there are advantages such as miniaturization of the curing device.

However, when spraying water from the nozzle in the form of mist, a curing trolley with nozzles arranged in the circumferential direction is used so that the surface of the lining concrete does not dry, that is, the mist does not disappear from the concrete surface. It is necessary to move it repeatedly automatically or semi-automatically, but in order to perform this mist spraying more efficiently, (1) If the mist from the nozzle is expanded and sprayed over a wider area, the mist is sprayed. By expanding the attachment area, mist spraying can be performed effectively.
(2) If the efficiency of adhesion of the sprayed mist to the lining concrete can be improved, the mist spraying can be effectively performed.

Therefore, the main problem of the present invention is to spread the mist from the nozzle over a wider area and spray it when performing wet curing by spraying mist-like water on the concrete surface, and further to improve the adhesion efficiency of the mist to the concrete surface. The purpose is to improve the efficiency of mist spraying by improving it.

In order to solve the above-mentioned problems, as the present invention according to claim 1, in performing wet curing by spraying mist-like water from a nozzle toward the concrete surface after demolding.
By disposing a charging electrode in the vicinity of the nozzle portion of the nozzle and charging the sprayed water particles positively or negatively, the spray area can be expanded by the repulsive force between the charged water particles. A featured method of moist curing of concrete is provided.

In the invention according to claim 1, in performing wet curing by spraying mist-like water toward the concrete surface, the repulsive force of each charged water particle is applied to the mist-like water by giving a positive or negative charge. To expand the spray area. Therefore, the efficiency of mist spraying can be improved by expanding the spraying area.

The wetness of concrete according to claim 1, wherein the sprayed water particles are charged to a charge on the opposite side of the surface charge of the concrete to improve the adhesive force to the concrete surface by the Coulomb attraction. A curing method is provided.

In the invention according to claim 2, the sprayed water particles are charged with a charge on the opposite side of the surface charge of the concrete to improve the adhesive force to the concrete surface. Therefore, the efficiency of mist spraying can be improved by improving the adhesive force of the concrete surface.

As described in detail above, according to the present invention, in performing wet curing by spraying mist-like water on a concrete surface, the mist from the nozzle is spread over a wider area and sprayed, and further, the mist adheres to the concrete surface. It is possible to improve the efficiency of mist spraying by improving the efficiency.

It is a tunnel vertical sectional view which shows the work procedure in a tunnel. It is a vertical sectional view of the sprinkler 1 to which the method of this invention was applied. It is the front view. It is an enlarged view which shows the drive wheel part of a watering device 1. It is an enlarged view which shows the limit switch of a watering device 1. It is a perspective view of the main part of the sprinkler equipment 11. It is an enlarged view of the watering nozzle 31 part. It is a flow chart of the wet curing method of lining concrete. It is a perspective view of the main part of the sprinkler equipment 11 which shows the other structural example of the charging electrode 32. It is an enlarged sectional view of the watering nozzle 31 part. It is a figure which shows the vertical spray test procedure and result in an Example. It is a figure which shows the parallel spray test procedure and result in an Example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in Fig. 1, in the construction of a mountain tunnel, after digging due to rupture, etc., sprayed concrete is applied to the inner wall surface of the excavated tunnel by spraying, rock bolts are driven in, and then an excavation machine such as a hydraulic excavator is installed. After excavating the invert at the bottom of the tunnel, placing invert concrete and backfilling it, a waterproof sheet was stretched on the inner peripheral surface of the sprayed concrete using the sheet trolley 2 (this surface is the ground side). (It will be a wall surface.), While moving the lining center 3 (movable steel formwork) in sequence in the tunnel axial direction, each span in the tunnel axial direction, with a distance from the ground side wall surface The formwork of the lining center 3 is installed along the direction, concrete 4 for lining is placed in the space between the side wall surface of the ground and the formwork, and after waiting for hardening, the mold is removed, and then the sprinkler 1 Wet curing according to the present invention has been carried out. Vehicles such as dump trucks and concrete mixer trucks are constantly running in the mine for unloading and concrete transportation.

The sprinkler 1 is installed behind the lining center 3 and sprays mist-like water toward the lining concrete 4 surface for a predetermined period after demolding for wet curing of the lining concrete 4. This is a device that performs wet curing.

Hereinafter, the sprinkler 1 will be described in detail with reference to the drawings.

As shown in FIGS. 2 and 3, the watering device 1 is supported by a moving pedestal 10 that can move in the tunnel axial direction in the tunnel axial direction, and the moving pedestal 10 and tunnels from the surface of the lining concrete 4. It is composed of a sprinkler facility 11 that sprays mist-like water onto four lining concrete surfaces from a position separated from the inside.

As shown in FIG. 3, the moving pedestal 10 is supported on the outside of a gate-shaped frame 12 made of a substantially gate-shaped steel frame material and the like, and is predetermined from the surface of the lining concrete 4. It is configured to include an arch-shaped frame 13 made of a steel frame or the like formed in a substantially arch shape along the circumferential direction of the tunnel at a position separated by a distance.

The moving pedestal 10 can be automatically reciprocated by wheels and a driving device on two traveling rails 14 and 14 arranged along the tunnel axial direction.

The traveling rail 14 supports the gate-shaped frame 12 of the moving pedestal 10 so as to be travelable, and two rails are laid on the lower surface of the tunnel along the longitudinal direction. As shown in detail in FIG. 4, the traveling rail 14 is composed of a rail body 14a on which the wheels 15 provided on the portal frame 12 travel and a channel steel in which the rail body 14a is supported in a groove. It is preferable that the pillow material is made of 14b. As a result, both side surfaces of the pillow material 14b are provided on both sides of the rail body 14a in an upright state.

At the lower end of the gantry frame 12, at least four wheels 15, 15 ... Rolling on the traveling rail 14 are provided, and at least one of the wheels 15 is rotationally driven by a geared motor 16 or the like to drive the gantry. The frame 12 is configured to be able to automatically reciprocate on the traveling rails 14, 14.

Since the sprinkler 1 is movably provided on the traveling rails 14 and 14 in this way, the length of the sprinkler in the tunnel axial direction is set to the length of the lining concrete casting span as in the conventional sprinkler. It is not necessary to form the length over the entire length, and the length can be shorter than one span in which the lining concrete is placed, so that the sprinkler can be made compact.

The moving speed of the watering device 1 can be arbitrarily set, but is preferably about 1 to 20 m / min, particularly about 3 to 8 m / min.

Since the sprinkler 1 automatically reciprocates on the traveling wheel 14, the moving pedestal 10 can swing in the moving direction at the front and rear ends in the moving direction, as shown in FIG. A limit switch 17 is provided which includes a free end portion 17a and a switch 17b that transmits a signal for rotating the wheel 15 in the reverse direction by swinging the free end portion 17a. Further, limit switch contact portions 18 are provided at the front and rear ends of the predetermined curing section of the traveling rail 14 so that the free end 17a of the limit switch 17 comes into contact with each other. As a result, the sprinkler 1 can automatically reciprocate within a predetermined curing section provided with the limit switch contact portions 18, 18.

The limit switch contact portion 18 is provided at the front and rear end portions of an arbitrary predetermined section in which the water sprinkler 1 is to be reciprocated. The moving section can be arbitrarily set, but it is preferably about 3 to 12 spans (about 30 to 130 m) in which the lining concrete 4 is placed. As shown in FIG. 5, the limit switch contact portion 18 is fixed to the traveling rail 14 by being supported on the upright side surface of the pillow material 14b by two bolts 18a and 18a separated along the longitudinal direction of the rail. Is done by.

Further, as an emergency measure when the moving pedestal 10 is not moved in the opposite direction by the limit switch 17, an emergency stop projecting forward in the moving direction at both ends of the moving pedestal 10 in the moving direction. It is preferable that the device 19 is provided and the emergency stop device contact portion 20 to which the emergency stop device 19 contacts is provided outside the limit switch contact portion 18 of the traveling rail 14 (see FIG. 2). .. As a result, even if the limit switch 17 gets over the limit switch contact portion 18 and moves outward, the emergency stop device 19 comes into contact with the emergency stop device contact portion 20 and the moving stand 10 moves. Can be stopped completely.

Further, by providing a sensing device (not shown) capable of detecting an object or a person in front of and behind the sprinkling device 1, a function of automatically stopping the sprinkling device 1 may be provided.

As shown in FIG. 2, the mobile pedestal 10 is connected to a power cable 21 such as the geared motor 16 and a water supply pump 34 for watering, which will be described in detail later. It is preferable that the power cable 21 is wound around an automatic reel 22 that automatically stretches and winds in conjunction with the movement of the moving frame 10. As a result, the power cable 21 is wired without slack, and it is possible to prevent the power cable 21 from being entangled and stopping the movement of the moving pedestal 10 or the power cable 21 from being disconnected.

The internal space of the gate-shaped frame 12 of the mobile mount 100 is a space through which tunnel construction machines such as dump trucks, concrete mixer trucks, and excavators can pass through.

As shown in FIG. 3, the arch-shaped frame 13 of the mobile gantry 10 allows the ventilation air pipe 5 of the tunnel to pass through the portion corresponding to the tunnel shoulder in the tunnel circumferential direction in the tunnel axial direction. It is preferable that the notch 23 is provided. In particular, as shown in FIG. 3, the ventilation air pipe 5 of the tunnel is arranged inside the arched frame 13, and the notch 23 has a width that allows the suspension bolt that suspends the ventilation air pipe 5 to pass through. It is desirable to allow it to be formed. As a result, the width of the notch 23 can be reduced, and watering by the watering facility 11 can be performed without a gap.

Inside the arch-shaped frame 13, a curing sheet 24 that also serves as waterproof is arranged. The curing sheet 24 is arranged on substantially the entire surface of the main body portion of the arch-shaped frame 13 that does not reach the sprinkler facility 11 that is provided so as to project from the arch-shaped frame 13. By providing the curing sheet 24, the sprayed mist is covered with the curing sheet 24 immediately after watering from the watering facility 11 provided on the front side in the moving direction, so that the lining concrete 14 surface is raised. It will be possible to maintain the condition of humidity. Of the sprinklers 11 and 11 provided on the front side and the rear side of the water sprinkler 1 in the traveling direction, in order to ensure that the effect of being covered with the curing sheet 24 immediately after watering is functioned. Water may be sprinkled only from the water sprinkling facility 11 provided on the front side, and may not be sprinkled from the water sprinkling facility 11 provided on the rear side. The curing sheet 24 may be provided discontinuously in the notch 23 of the arched frame 13, or may be provided continuously by bypassing the ventilation air duct 5.

Next, the sprinkler facility 11 will be described.

A plurality of the watering equipment 11 are arranged at a position separated from the surface of the lining concrete 4 inside the tunnel, along with a water supply pipe 30 arranged along the circumferential direction of the tunnel, and at predetermined intervals along the water supply pipe 30. In addition, it is provided with watering nozzles 31, 31 ... That sprinkle water toward the surface of the lining concrete 4. The sprinkler 11 is provided at both ends of the moving pedestal 10 in the moving direction or at either end, or in the illustrated example, both ends in the moving direction.

As shown in FIGS. 2 and 3, the water supply pipe 30 is provided at both ends or either end of the arch-shaped frame 13 in the traveling direction of the sprinkler device, and is provided along the arch-shaped frame 13 as well as at one end. It is arranged at a position protruding outward from the arch-shaped frame 13 in the traveling direction of the sprinkler 1. The water supply pipe 30 may be provided discontinuously in the notch 23 of the arched frame 13, or may be provided continuously by bypassing the ventilation air pipe 5.

A plurality of watering nozzles 31, 31 ... Are provided at predetermined intervals with respect to the water supply pipe 30. As shown in FIG. 6, the watering nozzle 31 is provided to the water supply pipe 30 via a connecting pipe 30a, and ejects water supplied from the tip of the nozzle through the water supply pipe 30 in the form of mist. Watering by the watering equipment 11 is performed on the front side and the rear side of the watering device 1 in the traveling direction, respectively, or either of them. The amount of water injected from the watering nozzle is preferably 0.01 to 1 liter / minute, particularly 0.1 to 0.3 liter / minute, and the injection angle is preferably about 60 to 120 °.

The arrangement interval of the watering nozzles 31 is preferably 10 to 100 cm, particularly 30 to 70 cm, along the water supply pipe 30. When the watering equipment 11 is provided on the front side and the rear side of the watering device 1, the watering nozzles 31 provided on the front side and the rear side may be arranged at the same positions on the front side and the rear side of the watering device 1, but the pitch is half. It is preferable that the lining concrete 4 is arranged so as to be staggered so that water can be evenly sprinkled on the surface of the lining concrete 4.

As shown in FIGS. 2 and 3, the mobile pedestal 10 is provided with a tank 33 for storing water for watering and a water supply pump 34 for supplying the water of the tank 33 to the water supply pipe 30. The water stored in the tank is pumped by the water supply pump 34 through the water supply pipe 30, and is sprayed from each watering nozzle 31.

As shown in FIGS. 6 and 7, the watering nozzle 31 is provided with a nozzle ejection portion in the vicinity of the nozzle ejection portion, specifically, in order to make the sprayed water positively or negatively charged. Charging electrodes 32 and 32 are arranged on both sides of the sandwich. Then, when the water supplied through the water supply pipe 30 is sprinkled toward the surface of the lining concrete 4, a high voltage current is passed through the charging electrodes 32 and 32 to spray the water from the watering nozzle 31. The water particles are charged with either a positive (plus) or negative (minus) charge to generate charged water particles.

As the charging electrode 32, any shape can be used as long as the water particles ejected from the watering nozzle 31 can be charged, but in the illustrated example, the charging electrode 32 is arranged substantially in parallel with the water supply pipe 30. Two rod-shaped electrodes are used. It is preferable that the charging electrodes 32 are arranged in two rows on both sides in the vicinity of the spout of the watering nozzle 31. By positively energizing the charging electrode 32, charged water particles charged with a negative charge can be generated, and by negatively energizing the charging electrode 32, charged water charged with a positive charge can be generated. Particles can be generated. As shown in FIG. 6, the charging electrode 32 is preferably fixed to the water supply pipe 30 (or the moving stand 10).

As the material of the charging electrode 32, generally used materials such as copper, copper alloy, and stainless steel can be widely adopted, but it is preferable to use stainless steel which is hard to rust. Further, as the shape of the charging electrode 32, it is preferable to use a rod-shaped one having a circular cross section, and it is preferable to use one having a diameter of 2 to 20 mm, particularly about 8 to 12 mm. The charging electrode 32 may be provided discontinuously in the notch 23 of the arched frame 13, or may be provided continuously by bypassing the ventilation air duct 5.

By applying a negative or positive charge to the water particles sprayed from the sprinkler nozzle 31, as shown in FIG. 7, assuming that the diameter of the spray area when no charge is applied is φ1, the repulsion of each charged water particle. The diameter of the spray area can be set to φ2 (> φ1) by force, and the spray area can be expanded by giving an electric charge to the sprayed water particles, so that the efficiency of mist spraying can be improved.

Since the effect of expanding the sprayed area is caused by the repulsive force of each charged water particle, the charge given to the water particle may be either positive or negative, but at this time, the sprayed water particle is lining concrete 4 It is more preferable to improve the adhesive force to the concrete surface by the Coulomb attraction by charging the electric charge on the opposite side of the surface charge.

The surface of the lining concrete 4 is usually positively charged by the presence of cations such as Ca ²⁺ , Na ⁺ , and K ⁺ Ma ²⁺ . Therefore, if the water particles to be sprayed are charged to the negative side and sprayed, a clone attraction acts between the concrete surface and the sprayed water particles, and the water particles are adsorbed on the concrete surface. The efficiency of adhesion of sprayed water to the concrete surface is improved.

In addition, it seems that the surface of ordinary concrete is charged to the positive side due to the influence of cations of metal elements in concrete, but the previous literature ("Modified belite cement using blast furnace slag fine powder" Effects of various factors on the permeation of salt in concrete ”Yoshida Yuki, Taguchi Fumio et al. According to the Annual Papers on Concrete Engineering Vol.26, No.1,2004), the pore surface of cement hardening using blast furnace slag fine powder. Has been reported to be charged on the negative side, so when charging the spray water, the potential of the concrete surface is measured with a surface potential meter (for example, Koganei Co., Ltd., non-contact handy surface potential meter DTY-KVS11). ), Etc., and then give the spray water a charge on the opposite side of the surface potential of the lining concrete.

The sprinkler 1 is provided with a control panel 35 that controls the operation of the geared motor 16 and the water supply pump 34. The control panel 35 further includes a determination means and the like, which will be described later, and controls the operation of the sprinkler 1.

As shown in FIG. 8, the operation control of the water sprinkler 1 first measures whether the surface of the lining concrete 4 is positively charged or negatively charged. Based on the surface potential measurement result of the lining concrete 4, the energization state of the charging electrode 32 is switched. For example, when the lining concrete 4 is positively charged, spray water charged with a negative charge opposite to this charge is sprinkled, and when the lining concrete 4 is negatively charged. Is to sprinkle spray water charged with a positive charge opposite to this charge.

The operation or stop of the sprinkler 1 is determined when the humidity on the surface of the lining concrete 4 exceeds a predetermined threshold according to the measurement result of a hygrometer (not shown) that measures the humidity on the surface of the lining concrete 4. , The main sprinkler 1 is operated for wet curing of the lining concrete 4. On the other hand, when the humidity on the surface of the lining concrete 4 is equal to or less than a predetermined threshold value, the operation of the sprinkler 1 may be stopped. The threshold value is preferably set to, for example, a relative humidity of about 85% RH.
[Examples of other forms]
(1) In the above embodiment, the charging electrode 32 is arranged in a state of being exposed to the outside, but it is also possible to arrange the charging electrode 32 so as not to be exposed in order to prevent electric leakage and electric shock. For example, as shown in FIG. 9, an electrode holding member 37 made of an insulating material such as synthetic resin or rubber is attached to the tip portion of the watering nozzle 31. As shown in FIG. 10, the electrode holding member 37 has a tubular shape so as to surround the periphery of the nozzle tip portion, and charging electrodes 38, 38 are arranged on the inner peripheral surface thereof. .. The power supply to the charging electrode 38 is provided by arranging the power cable 36 along the water supply pipe 30 and supplying the power from the electric wire 36a branched from the power line 36. The power cable 36 is fixed to the supply pipe 30 by binding bands 39 arranged at appropriate intervals.
(2) In the above embodiment, the present invention has been described by taking as an example the wet curing of lining concrete in a mountain tunnel, but the wet curing method according to the present invention also applies to underground structures such as culverts and underpasses. It can be applied in the same way.

Hereinafter, the effect of expanding the spray area when the mist sprayed from the watering nozzle is charged according to the present invention, and the charge of the spray water on the opposite side of the surface charge of the concrete, thereby applying the Coulomb attraction to the concrete surface. A verification experiment on the effect of improving the adhesive force will be described. Two experiments were conducted: a <vertical spray test> in which sprayed water was sprayed perpendicularly to the curing surface and a <parallel spray test> in which sprayed water was sprayed parallel to the curing surface, and the amount of water droplets adhered was large or small. The effects were verified by. The test procedure and test results will be described in detail below.
<Vertical spray test>
As shown in FIG. 11, a two-fluid nozzle (BIMV80075S303 + TS303) manufactured by Ikeuchi Co., Ltd. is used as the spray nozzle, and a water-sensitive test paper is used on the vertical wall surface: length 76 mm x width 52 mm (ground color is yellow and moisture). (It turns dark blue when it adheres.) Is attached, and the water pressure is 0. From the position 1500 mm away (data No. 1) and the position 1000 mm away (data No. 2) toward the water sensitive test paper, respectively. Spraying was performed for 30 seconds under the conditions of 1 MPa and air pressure: 0.1 MPa.

The test was carried out in three cases of no charge, positive charge, and negative charge by disposing a charging electrode near the tip of the nozzle, and the area where the color of the water sensitive test paper changed was calculated and compared. For the area comparison, the water-sensitive test paper was scanned, the area of the color-changed part was calculated using special software, and the area ratio to the total area (water-covered area ratio%) was used. According to the measurement by the surface electrometer, the water sensitive test paper was in a state of being charged on the negative side.

The test results are shown in FIG. In the data No. 1 (1500 mm), both the positively charged and negatively charged cases have a slightly larger water coverage area ratio than the uncharged cases, and when charged, the repulsion of charged water particles. It was found that the spray area was expanded by the force.

In addition, in comparison between positive charge and negative charge, the ratio of positive charge to negative charge is 111.9%, and the sprayed water particles are charged on the opposite side of the surface charge of the water sensitive test paper (negative charge). It was found that by charging, the adhesive force to the surface was improved by the Coulomb attraction.

Even in the case of data No. 2 (1000 mm), both the positively charged and negatively charged cases have a slightly larger water coverage area ratio than the uncharged cases, and when charged, charged water. It has been found that the repulsive force of the particles can expand the spray area, but when comparing the cases of positive charging and negative charging, most of the sprayed water reaches the water sensitive test paper, and there is a significant difference. There wasn't.
<Parallel spray test>
As shown in FIG. 12, a two-fluid nozzle (BIMV80075S303 + TS303) manufactured by Ikeuchi Co., Ltd. is used as the spray nozzle, and a water-sensitive test paper is used on the vertical wall surface: length 76 mm x width 52 mm (ground color is yellow and moisture). (It turns dark blue when it adheres) is attached, and the position directly above the position 400 mm away from the wall surface (data No. 3) and the position 200 mm away (data No. 4) (water sensitivity test paper) Spraying was performed for 30 seconds from (300 mm above the center) downward under the conditions of water pressure: 0.1 MPa and air pressure: 0.1 MPa.

The test was carried out in three cases of no charge, positive charge, and negative charge by disposing a charging electrode near the tip of the nozzle, and the area where the color of the water sensitive test paper changed was calculated and compared. For the area comparison, the water-sensitive test paper was scanned, the area of the color-changed part was calculated using special software, and the area ratio to the total area (water-covered area ratio%) was used. According to the measurement by the surface electrometer, the water sensitive test paper was in a state of being charged on the negative side.

The test results are shown in FIG. In data No. 3 (400 mm), the water-sensitive test paper did not get wet in the non-charged case, but the water-covered area ratio was 3.804% in the positively charged case and the water-covered area in the negatively charged case. The rate was 2.379%, and when charged, it was found that the spray area was expanded due to the repulsive force of the charged water particles.

In addition, in comparison between positive charge and negative charge, the ratio of positive charge to negative charge is 159.9%, and the sprayed water particles are charged on the opposite side of the surface charge of the water sensitive test paper (negative charge). It was found that by charging, the adhesive force to the surface was improved by the Coulomb attraction.

Even in the case of data No. 4 (200 mm), the water sensitive test paper hardly got wet in the case without charging, but the water coverage area ratio was 90.04% in the case with positive charging, and the case with negative charging. The water coverage ratio was 79.748%, and it was found that the spray area was expanded by the repulsive force of the charged water particles when either positive or negative was charged.

In addition, in comparison between positive charge and negative charge, the ratio of positive charge to negative charge is 112.9%, and the sprayed water particles are charged on the opposite side of the surface charge of the water sensitive test paper (negative charge). It was found that by charging, the adhesive force to the surface was improved by the Coulomb attraction.

1 ... watering device, 2 ... seat trolley, 3 ... lining centre, 4 ... lining concrete, 10 ... mobile mount, 11 ... watering equipment, 12 ... gate-shaped frame, 13 ... arch-shaped frame, 14 ... traveling rail, 15 ... Wheels, 16 ... Geared motor, 17 ... Limit switch, 18 ... Limit switch contact part, 19 ... Emergency stop device, 20 ... Emergency stop device contact part, 21 ... Power cable, 22 ... Automatic reel, 23 ... Notch Part, 24 ... Curing sheet, 30 ... Watering pipe, 31 ... Watering nozzle, 32 ... Charging electrode, 33 ... Tank, 34 ... Water pump, 35 ... Control panel, 36 ... Power cable, 37 ... Electrode holding member, 38 … Charging electrode

Claims (2)

Wet curing is performed by spraying mist-like water from the nozzle toward the concrete surface after demolding.
By disposing a charging electrode in the vicinity of the nozzle portion of the nozzle and charging the sprayed water particles positively or negatively, the spray area can be expanded by the repulsive force between the charged water particles. A characteristic method of moist curing of concrete. The method for moist curing concrete according to claim 1, wherein the sprayed water particles are charged with an electric charge on the opposite side of the surface charge of the concrete to improve the adhesive force to the concrete surface by the Coulomb attraction.

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