JP6480767B2 - Method for treating concrete joint surface, concrete joint surface processing apparatus, and concrete placing method - Google Patents

Description

  The present invention relates to a concrete joining surface processing method, a concrete joining surface processing apparatus, and a concrete placing method.

  Conventionally, for example, a concrete placing method described in Patent Document 1 is known. In the placement method of Patent Document 1, after placing the primary concrete, the setting (solidification) of the thin layer portion is systematically delayed by spraying a setting retarder on the joint surface of the primary concrete. A latency layer is formed. Then, the latency layer is removed by spraying high-pressure water on the joining surface, and coarse aggregate grains are exposed from the joining surface. Thereby, the joining surface is roughened. Thereafter, secondary concrete is placed on the joining surface. In this placing method, since the secondary concrete is placed on the roughened joining surface, the tensile strength at the joining surface is ensured.

JP 2002-276156 A

  However, in the processing method of the joining surface of the said patent document 1, the process of the muddy water which arises by spraying of high pressure water becomes a problem. For example, in the case of a bridge construction in which a concrete structure is constructed on a river, muddy water cannot be drained directly to the river, so large-scale facilities such as muddy water treatment facilities are required. Moreover, the situation where muddy water cannot be drained by other requests and various regulations is also assumed, and in these cases, the treatment of muddy water becomes a problem.

  Therefore, the present invention has an object to provide a concrete joining surface treatment method, a concrete joining surface treatment apparatus, and a concrete placing method capable of removing a latency layer without using high-pressure water and suppressing generation of muddy water. And

  The method for treating a concrete joint surface according to the present invention includes a retarder spraying step for spraying a setting retarder to a cast surface of the cast concrete, and a latency layer formed on the joint surface by spraying the set retarder. On the other hand, it includes a removing step of spraying granular dry ice to remove the latency layer and exposing the concrete coarse aggregate from the joint surface.

  In this method for treating a concrete transfer surface, the latency layer is removed by spraying granular dry ice instead of high-pressure water. The sprayed dry ice changes from solid to gas by the sublimation action and diffuses into the air. Therefore, the latency layer can be removed without using high-pressure water, and generation of turbid water can be suppressed.

  In the removing step, dry ice may be sprayed at an injection pressure of 1.2 MPa or more and 3.0 MPa or less. In this case, since the spray pressure of dry ice is increased, the removal property of the latency layer by dry ice can be improved, and the working efficiency can be improved and the removal of the latency layer can be realized.

  In the removing step, dry ice having a Mohs hardness of 2.5 or more and 3.0 or less may be sprayed. In this case, since the hardness of the dry ice is increased, the removal characteristic of the latency layer by dry ice can be improved, the working efficiency can be improved, and the reliable removal of the latency layer can be realized.

  Further, in the removing step, dry ice may be sprayed in a cover that covers the joining surface and the dry ice injection port. In this case, the dust of the latency layer peeled off from the joining surface can be retained in the cover, and scattering of the dust can be suppressed.

  A concrete joint surface treatment apparatus of the present invention is a concrete joint surface treatment apparatus for removing a latency layer formed on a concrete joint surface, and sprays granular dry ice toward the latency layer. A dry ice supply unit that supplies dry ice to the nozzle, a cover that covers the joining surface and the nozzle nozzle, and a dust layer of the latency layer that has been peeled off from the joining surface, is sucked inside the cover, And a discharge part for discharging.

  In this concrete joining surface treatment apparatus, granular dry ice is sprayed from a nozzle and sprayed onto the joining surface to remove the latency layer. The sprayed granular dry ice changes from solid to gas by the sublimation action and diffuses into the air. Therefore, the latency layer can be removed without using high-pressure water, and generation of turbid water can be suppressed. Moreover, since the dust of the latency layer peeled off from the joining surface is fastened in the cover, and the dust fastened in the cover is discharged from the discharge part, scattering of dust can be suppressed.

  The dry ice supply unit may supply dry ice to the nozzle with compressed air having a pressure of 1.2 MPa or more and 3.0 MPa or less. In this case, since the spray pressure of dry ice is increased, the removal property of the latency layer by dry ice can be improved, and the working efficiency can be improved and the removal of the latency layer can be realized.

  The dry ice supply unit may supply dry ice having a Mohs hardness of 2.5 to 3.0 to the nozzle. In this case, since the spray pressure of dry ice is increased, the removal property of the latency layer by dry ice can be improved, and the working efficiency can be improved and the removal of the latency layer can be realized.

  The concrete placing method of the present invention includes a primary concrete placing step for placing primary concrete, a retarder spraying step for spraying a set retarder on the joint surface of the primary concrete, and a casting surface by spraying the set retarder. Spraying granular dry ice to the latency layer formed on the surface to remove the latency layer, exposing the coarse aggregate of the primary concrete from the joining surface, and placing secondary concrete on the joining surface And a secondary concrete placing process.

  In this concrete casting method, the latency layer is removed by spraying granular dry ice instead of high-pressure water. The sprayed dry ice changes from solid to gas by the sublimation action and diffuses into the air. Therefore, the latency layer can be removed without using high-pressure water, and generation of turbid water can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, a latency layer can be removed without using high-pressure water, and the concrete joining surface processing method, concrete joining surface processing apparatus, and concrete placing method which can suppress generation | occurrence | production of muddy water can be provided.

It is a schematic perspective view of the concrete joining surface processing apparatus of embodiment. It is a schematic block diagram of the concrete joining surface processing apparatus of FIG. It is a flowchart which shows the process sequence of the concrete placement method of embodiment. (A) is a schematic sectional drawing of the joining surface vicinity in a retarder spraying process, (b) is a schematic sectional drawing of the joining surface vicinity in a removal process.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a schematic perspective view of a concrete joining surface processing apparatus 1 according to an embodiment. FIG. 2 is a schematic configuration diagram of the concrete joining surface treatment apparatus 1 of FIG. As shown in FIGS. 1 and 2, the concrete joining surface treatment apparatus 1 is formed on the joining surface 3 when the secondary concrete is handed over the joining surface 3 of the placed primary concrete 2. Used to remove the latency layer 4. The latency layer 4 is an uncured thin layer formed on the surface of the joining surface 3, and is formed by spraying a setting retarder on the joining surface 3 of the primary concrete 2 after placing, as will be described later. Has been.

  As shown in FIGS. 1 and 2, the concrete joining surface treatment apparatus 1 includes a substantially box-shaped cover 10 and a handle portion 13 provided on the cover 10. The cover 10 has wheels (movement mechanisms) 12 for movement on the left and right sides. The handle portion 13 has a pair of support portions 14 connected to the left and right sides of the cover 10, and a grip portion 15 that connects the tips of the pair of support portions 14.

  In addition to the cover 10, the concrete transfer surface treatment apparatus 1 includes a nozzle 20 (see FIG. 2) that sprays granular dry ice 16 toward the latency layer 4, and a dry unit that supplies the dry ice 16 to the nozzle 20. The ice supply part 30 and the discharge part 40 which discharges the dust of the latency layer 4 peeled from the joining surface 3 to the exterior of the cover 10 are provided. The dry ice supply unit 30 includes a dry ice tank 32 that stores the dry ice 16, a compressor 34 that generates compressed air, and a supply pipe 36 that connects the nozzle 20, the dry ice tank 32, and the compressor 34. ing.

  The cover 10 opens to the connecting surface 3 side, and covers the connecting surface 3 (latency layer 4) and the injection port 22 of the nozzle 20. The nozzle 20 injects the dry ice 16 in the cover 10. More specifically, the nozzle 20 is connected to the supply pipe 36 via the cylindrical connecting portion 24, and the compressed air from the compressor 34 becomes a carrier of the dry ice 16, so that the nozzle 20 is dried from the injection port 22. Ice 16 is jetted. The connecting portion 24 is provided so as to penetrate the bottom surface of the cover 10. When using the concrete joining surface treatment apparatus 1, the user U grips the grip portion 15, for example, rolls the wheel 12 by applying a force to the handle portion 13 back and forth, and covers the cover 10 on the joining surface 3. Move. Thus, the concrete joining surface treatment apparatus 1 can be freely moved by the user U, and can be used for treating a wide range of joining surfaces 3.

  For example, the nozzle 20 is disposed such that the distance from the injection port 22 to the joining surface 3 (hereinafter referred to as “injection height”) is 10 cm or more and 15 cm or less. Specifically, the injection height is determined by the relationship between the wheel 12 that rolls in contact with the joining surface 3 and the injection port 22, and is based on the plane that includes the lower end (joining surface contacting portion) of the wheel 12. Assuming the installation surface, it is the height from this reference grounding surface to the injection port 22. The jet height is preferably 15 cm or less because a smaller jet height is preferable in order to improve the removal characteristic of the latency layer 4 by the dry ice 16. On the other hand, if the injection height is too small, the spraying range is narrowed, so that it is 10 cm or more. The nozzle 20 may have a mechanism that makes the ejection height variable. Such a mechanism is realized, for example, by enabling the nozzle 20 to expand and contract in the axial direction.

  Moreover, the spraying direction of the dry ice 16 with respect to the joining surface 3 by the nozzle 20 may be orthogonal to the reference ground surface or may be inclined. Specifically, the injection direction is a direction orthogonal to a plane including the injection port 22. For example, when the plane including the ejection port 22 and the axis of the nozzle 20 are orthogonal to each other as in the present embodiment, the ejection direction coincides with the axial direction of the nozzle 20. When the injection direction is orthogonal to the reference ground plane, local spraying is possible, which is advantageous for improving the removal characteristics. On the other hand, an increase in the angle of inclination between the injection direction and the reference ground plane is advantageous for expanding the spray range. The nozzle 20 may have a mechanism that makes the ejection direction variable. Such a mechanism is realized by, for example, a configuration in which the connecting portion 24 is pivotally supported with respect to the cover 10 by a pin, and the connecting portion 24 can be swung in the left-right direction with respect to the cover 10.

  The dry ice tank 32 stores the granular dry ice 16 and supplies the stored dry ice 16 to the supply pipe 36. The dry ice tank 32 is connected to, for example, a dry ice making machine (not shown). In this example, the dry ice making machine produces dry ice 16 having a Mohs hardness of 2.5 or more and 3.0 or less by extrusion molding from rectangular parallelepiped square dry ice. The dry ice 16 manufactured in this way has a cubic shape with a side length of 3 mm, for example.

  The compressor 34 generates compressed air and supplies the generated compressed air to the supply pipe 36. For example, the compressor 34 generates compressed air having a pressure of 1.2 MPa or more and 3.0 MPa or less. The dry ice supply unit 30 supplies the dry ice 16 to the nozzle 20 by this compressed air. Therefore, the dry ice 16 is injected from the injection port 22 at an injection pressure of 1.2 MPa or more and 3.0 MPa or less, for example.

  The discharge part 40 has a discharge pipe 42 in which a suction port 44 is formed. The discharge pipe 42 is provided through the cover 10 so that the suction port 44 is positioned in the cover 10. The discharge unit 40 sucks dust (latency component) of the latency layer 4 peeled from the joining surface 3 from the suction port 44 in the cover 10 and discharges the dust to the outside of the cover 10. The other end side of the discharge pipe 42 is connected to, for example, a dust disposal apparatus. The discharge pipe 42 may be bundled with the supply pipe 36. In this case, it is preferable from the viewpoint of space saving and workability improvement.

  Next, a concrete joining surface processing method using the concrete joining surface processing apparatus 1 and a concrete placing method including the concrete joining surface processing method will be described. FIG. 3 is a flowchart illustrating a processing procedure of the concrete placing method according to the embodiment. FIG. 4A is a schematic cross-sectional view in the vicinity of the concrete joining surface in the retarder spraying step, and FIG. 4B is a schematic cross-sectional view in the vicinity of the concrete joining surface in the removal step.

  In this concrete placing method, first, after assembling the scaffold, a primary concrete placing step for placing the primary concrete 2 is performed (S11). For example, after a reinforcing bar is assembled at the placement position of the primary concrete 2, a mold is installed so as to surround the placement position, and the primary concrete 2 is driven into the installed mold. The primary concrete 2 includes cement, coarse aggregate, fine aggregate, and the like.

Next, a retarding agent spraying step for spraying a set retarder on the joint surface 3 of the primary concrete 2 is performed (S12). For example, after completion of the driving, the setting retarder is sprayed when bleeding water generation stops (for example, after 2 to 3 hours). As the setting retarder, an inorganic or organic retarder may be used. The application amount of the setting retarder is, for example, about 300 g / m ² . After the setting retarder is sprayed, sealing curing is performed using, for example, a vinyl sheet. By this retarder spraying step, the hardening (solidification) of the thin layer portion on the surface of the joining surface 3 is delayed, and the latency layer 4 is formed on the joining surface 3 as shown in FIG. The thickness of the latency layer 4 is, for example, about 5 to 10 mm.

  Next, the removal process which sprays granular dry ice 16 with respect to the latency layer 4 and removes the latency layer 4 is implemented (S13). By removing the latency layer 4 in the removal step, as shown in FIG. 4B, the coarse aggregate 5 of the primary concrete 2 is exposed from the joint surface 3, and the joint surface 3 is roughened. The In the removing step, the concrete joining surface treatment apparatus 1 is used, and for example, dry ice 16 is sprayed at an injection pressure of 1.2 MPa to 3.0 MPa. For example, dry ice 16 having a Mohs hardness of 2.5 to 3.0 is sprayed. The spraying of the dry ice 16 is performed in the cover 10. The dry ice 16 sprayed on the joining surface 3 in the cover 10 dries the latency layer 4 when sublimating, and peels the latency component (dust of the latency layer 4) from the joining surface 3. The separated dust of the latency layer 4 is sucked by the discharge unit 40 and discharged to the outside of the cover 10. The method for treating a concrete joint surface of the present invention includes the above-mentioned retarder spraying step and removing step.

  Subsequently, a secondary concrete placing step of placing secondary concrete on the roughened joint surface 3 is performed (S14). As the secondary concrete, for example, the same concrete as the primary concrete 2 is used. . In addition, before the secondary concrete placing step, the roughened joint surface 3 is subjected to flooding curing. By the secondary concrete placing process, the joining of the secondary concrete onto the joining surface 3 of the primary concrete 2 is completed. Thereafter, for example, a step of casting the concrete onto the placed secondary concrete is performed.

  In the concrete joining surface processing apparatus 1, the concrete joining surface processing method, and the concrete placing method described above, the latency layer 4 is removed by spraying granular dry ice 16. The sprayed dry ice 16 changes from a solid to a gas by a sublimation action and diffuses into the air. Therefore, the latency layer 4 can be removed without using high-pressure water, and generation of muddy water can be suppressed. In particular, when a large structure such as a bridge is constructed, the joining surface 3 becomes large, and the processing steps associated with the concrete placement increase. Therefore, the effect of suppressing the generation of muddy water by the concrete joining surface treatment apparatus 1 that can remove the latency layer 4 without using high-pressure water, the concrete joining surface treatment method, and the concrete placing method is also increased. Moreover, as a result of suppressing generation | occurrence | production of muddy water, the work efficiency of construction improves dramatically.

  In addition, since the dry ice 16 is sprayed at a spray pressure of 1.2 MPa or more and 3.0 MPa or less in the removing step, and the spray pressure of the dry ice 16 is increased, the removal characteristic of the latency layer 4 by the dry ice 16 is improved. It is possible to improve the working efficiency and to surely remove the latency layer 4.

  In addition, 1.5 MPa or more may be sufficient as the injection pressure which sprays the dry ice 16 in a removal process, and 1.8 MPa or more may be sufficient as it. The higher the injection pressure, the better the removal characteristic of the latency layer 4 by the dry ice 16. The injection pressure may be 2.7 MPa or less, or 2.4 MPa or less. If the latency layer 4 can be removed to the required level, the energy efficiency can be improved with a lower injection pressure.

  In addition, since the dry ice 16 having a Mohs hardness of 2.5 or more and 3.0 or less is sprayed in the removing process and the hardness of the dry ice 16 is increased, the removal characteristic of the latency layer 4 by the dry ice 16 is improved. It is possible to improve work efficiency and reliably remove the latency layer 4.

  Further, since the dry ice 16 is blown in the cover 10 that covers the joining surface 3 and the spray nozzle 22 of the dry ice 16 in the removing process, the dust of the latency layer 4 peeled off from the joining surface 3 is removed in the cover 10. The dust can be prevented from being scattered. Further, the dust in the latency layer 4 held in the cover 10 is discharged to the outside of the cover 10 by the discharge unit 40.

[Verification test 1]
The result of the confirmation test conducted to confirm the effect of the present invention will be described.

Example 1
As Example 1, the above-described method for treating a concrete joint surface (dry ice blasting) was performed on the joint surface of a square concrete specimen having a side of 1.0 m. The concrete launch height was 90 mm. As the concrete, ordinary cement having a nominal strength of 27, a slump of 8 cm, and a coarse aggregate with a maximum dimension of 20 mm was used. Using “Disparlight CR” manufactured by Nippon Zikkou Co., Ltd. as a setting retarder, 300 g / mm ² was uniformly sprayed on the entire surface of the joint. The spraying pressure of dry ice in the removing step was 2.1 MPa. Also, the Mohs hardness of the dry ice was about 3, and the shape of the dry ice was a cubic shape with a side length of 3 mm. As a dry ice manufacturing machine, a dry ice cleaning device manufactured by Green Tech Japan Co., Ltd. was used.

(Evaluation method)
The processing completion time until it was judged that the removal of the latency layer of the entire joining surface was completed by visual observation by the experimenter was measured. In Example 1, the processing completion time was 4 minutes and 0 seconds.

(Comparative Example 1)
In the comparative example 1, the processing method by the conventional high pressure water (high washer) was used instead of the processing method of the concrete joint surface mentioned above. The other points were the same as in Example 1 above. The water pressure (injection pressure) of the high-pressure water was 4.9 MPa. Evaluation was performed in the same manner as in Example 1 above. In Comparative Example 1, the processing completion time was 2 minutes 30 seconds.

  Since the removal of the latency layer in Example 1 was completed, it was confirmed that the latency layer could be removed by the above-described method for treating the concrete joint surface as in the case of using high-pressure water. Moreover, from the comparison of the results of Example 1 and Comparative Example 1, in Example 1, the injection pressure of about 0.43 (2.1 MPa / 4.9 MPa) times that of Comparative Example 1 was about 0.003 of Comparative Example 1. It can be seen that the processing was completed in 63 times (150 seconds / 240 seconds) times. From this, it was confirmed that the above-described method for treating a concrete joint surface can ensure the same work efficiency as the method for treating with high-pressure water.

[Confirmation test 2]
(Example 2)
In Example 2, the spray pressure of dry ice in the removing process was set to 0.69 MPa. Dry ice is sequentially sprayed over the entire joining surface so that the latency layer is uniformly removed from the joining surface, and after 14 minutes 20 seconds have elapsed after the start of processing (after the start of dry ice spraying) Ended. The other points were the same as in Example 1 above.

(Evaluation method)
About Example 2 for 5 trials, the adhesion strength by the Kenken-type tensile test was measured. As the material of the deposit, a material with high adhesion (High Quick manufactured by Cemedine Co., Ltd.) was used so that the base material (concrete side) was broken. The test range was a square region with a side of 1.0 m at the corner of the joint surface. Table 1 shows the tensile strength (N / mm ² ) and the average value in each trial. A higher tensile strength value indicates that the latency layer does not remain and the latency layer is removed well.

(Comparative Example 2)
In Comparative Example 2, the same conditions as in Comparative Example 1 were used. After the start of treatment (after the start of spraying of high-pressure water), the treatment was terminated when 2 minutes and 30 seconds passed. For Comparative Example 2 for 5 trials, the adhesion strength was measured in the same manner as in Example 2. Table 1 shows the tensile strength (N / mm ² ) and the average value in each trial.

As shown in Table 1, the average value of the tensile strength of Example ² (4.84N / mm 2) was similar to the average value of the tensile strength of Comparative Example ² (4.72N / mm 2) . From this, it was confirmed that the treatment method of the concrete joint surface described above can remove the latency layer to the same extent as the treatment method using high-pressure water. Moreover, in Example 2, it processed only about 0.17 (150 second / 860 second) time of the comparative example 2 by the injection pressure of about 0.14 (0.69 MPa / 4.9 MPa) time of the comparative example 2 times. By doing so, the latency layer could be removed to the same extent as in Comparative Example 2. From this, it was confirmed that the above-described method for treating a concrete joint surface can ensure the same work efficiency as the method for treating with high-pressure water.

DESCRIPTION OF SYMBOLS 1 ... Concrete transfer surface processing apparatus, 2 ... Primary concrete, 3 ... Transfer surface, 4 ... Lateance layer, 10 ... Cover, 16 ... Dry ice, 20 ... Nozzle, 22 ... Injection port, 30 ... Dry ice supply part, 40 ... discharge part.

Claims (4)

A retarder spraying step of spraying a set retarder on the joint surface of the cast concrete;
Removal step of spraying granular dry ice to the latency layer formed on the joining surface by spraying the setting retarder to remove the latency layer and exposing the coarse aggregate of the concrete from the joining surface and, only including,
In the removal step, the concrete joining surface is treated by spraying the dry ice at an injection pressure of 1.2 MPa or more and 3.0 MPa or less . In the removing step, Mohs hardness blow 2.5 to 3.0 of the dry ice, the processing method of the concrete joint surface according to claim 1. The processing method of the concrete joining surface of Claim 1 or 2 which sprays the said dry ice in the cover which covers the said joining surface and the injection opening of the said dry ice in the said removal process. A primary concrete placing process for placing primary concrete;
A retarder spraying step of spraying a set retarder on the joint surface of the primary concrete;
Removing the latency layer by spraying granular dry ice on the latency layer formed on the joining surface by spraying the setting retarder, and removing the coarse aggregate of the primary concrete from the joining surface Process,
Look including a secondary concreting step of pouring the secondary concrete on the punching joint surface,
In the removing step, a concrete placement method in which the dry ice is sprayed at an injection pressure of 1.2 MPa to 3.0 MPa.

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