Concrete surface mixing device

Abstract

To provide a method of improving quality of a concrete surface layer and its agitator, by which: setting time of concrete is not significantly delayed even in cold weather; and labor time of participant such as site workers can be reduced; and the amount of setting accelerator used can be reduced because it is not necessary to apply setting accelerator to entire concrete placed, accordingly reducing costs; and further finishable time of the concrete surface layer can be reduced by using the agitator.SOLUTION: After placing the concrete, concrete surface is sprinkled with a setting accelerator 18, and the sprinkled setting accelerator 18 and the placed concrete are agitated from the surface of the concrete to a desired depth of modification of the concrete to change properties of the concrete from the surface of the agitated concrete to the desired depth to accelerate concrete setting.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method for improving the quality of the concrete surface layer and its stirring device.

Background Art

[0002] In concrete construction during the cold period, the setting time of concrete is significantly delayed, so finishing work such as slabs may be carried out at night. In addition, since it is difficult to accurately predict the start of setting, related parties such as on-site workers have to wait on-site until the start of finishing work, resulting in a problem of longer working hours.

[0003] In response to these problems, conventionally, as a method for shortening the finishable time of the concrete surface, a powdery setting accelerator (2 - 6 kg / m 3 ) packed in a soluble paper bag is put into an agitator truck etc. on-site and stirred.

[0004] However, in the method of adding a setting accelerator to a batcher plant or an agitator truck at a fresh concrete factory as in the conventional method, the amount used increases because the setting accelerator is applied to the entire concrete to be placed, resulting in a problem of increased cost.

[0005] Therefore, if only the covering part of the concrete surface layer can be promoted to set, the finishable time can be shortened while suppressing the cost. That is, for the purpose of shortening the finishable time of the concrete surface layer, the range that requires promotion of setting is only the surface layer of the concrete. Therefore, the present invention sprays a setting accelerator immediately after placing, and uses the stirring device of the present invention to uniformly stir the concrete surface layer, thereby shortening the finishable time of the surface layer.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-63884 [Overview of the project] [Problems that the invention aims to solve]

[0007] Thus, the present invention was devised to address the aforementioned conventional problems, and aims to provide a method for improving the quality of the concrete surface layer and a mixing device thereof, which, for example, prevents a significant delay in the setting time of concrete during concrete construction in cold seasons, thereby shortening the working hours of on-site workers and other related parties, reduces the amount of setting accelerator used because it is not necessary to apply it to the entire concrete being poured, thereby leading to cost reduction, and further shortens the time required to finish the concrete surface layer by using a mixing device. [Means for solving the problem]

[0008] The present invention It comprises a drive member, a rotating shaft that rotates in conjunction with the drive member and extends horizontally from its base end, a group of stirring blades attached to the outer surface of the rotating shaft and rotating axially in accordance with the rotation of the rotating shaft, and a guide plate that extends horizontally from the base end, is provided parallel to the rotating shaft, and is located on the rear side of the rotating shaft in the direction of travel. The stirring device is configured as follows: The aforementioned stirring blade group is composed of a plurality of stirring blades, and these plurality of stirring blades are mounted at intervals in the axial direction of the rotation shaft, so that adjacent stirring blades intersect on the rotation shaft. The stirring blade is configured to be inclined with respect to the axial direction, and when the stirring blade rotates, The surface of concrete poured during concrete construction It can be stirred to a predetermined depth. The guide plate has a downward slope from the front to the rear in the direction of travel of the stirring device, and the lower rear end of the downward slope is configured to contact the surface layer of the concrete after stirring. As the stirring device moves forward in the direction of travel while in contact, the surface layer of the concrete after stirring can be made smooth. It is characterized by the following: or The guide plate has a depth adjustment section that adjusts the depth from the concrete surface to which the stirring blade group stirs, The depth adjustment unit adjusts the depth to which the stirring blades are inserted from the concrete surface to a predetermined depth for stirring, and the rear lower end of the guide plate is fixed at the adjusted predetermined depth. It is characterized by the following: or The aforementioned stirring device is equipped with a handle for carrying, and can be operated by gripping the handle. It is characterized by the following: [Effects of the Invention]

[0009] According to the present invention, for example, in concrete construction during cold seasons, the setting time of the concrete will not be significantly delayed, thereby reducing the working hours of on-site workers and other related personnel. Furthermore, since it is not necessary to apply a setting accelerator to the entire poured concrete, the amount of setting accelerator used can be reduced, leading to cost reductions. In addition, by using a mixing device, the time required to finish the surface layer of the concrete can be shortened. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram (1) showing the configuration of the stirring device of the present invention. [Figure 2] This is a schematic diagram (2) showing the configuration of the stirring device of the present invention. [Figure 3] This is a schematic diagram (3) showing the configuration of the stirring device of the present invention. [Figure 4] This is an explanatory diagram (1) illustrating the schematic configuration of the construction method of the present invention. [Figure 5] This is an explanatory diagram (2) illustrating the schematic configuration of the construction method of the present invention. [Figure 6] It is an explanatory diagram explaining the shortening effect of the setting time (finishing time) obtained by the construction method of the present invention. [Figure 7] It is an explanatory diagram explaining the influence on the concrete quality by the construction method of the present invention.

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described based on examples. First, the stirring device 1 of the present invention used when stirring the concrete surface layer portion 12 will be described.

[0012] FIG. 1 is a perspective view showing the stirring device 1 of the present invention. The stirring device 1 operates using a drive unit 2 such as a motor as a power source. As understood from FIG. 1, in the stirring device 1, a support rod 3 is connected to the front side of the drive unit 2, and an operation rod 4 is connected to the rear side. And a stirring part 5 is provided on the tip side of the support rod 3. Further, a power part 6 is provided at the end side of the operation rod 4, and the power part 6 uses a storage battery or the like to supply power to the drive unit 2.

[0013] The stirring part 5 includes a rotating shaft 7 that rotates in conjunction with the power of the drive unit 2, and a cover member 8 having a substantially semi-circular arch shape is attached to the base end side of the rotating shaft 7 on the front side in the advancing direction of the rotating shaft 7. And a plurality of stirring blades 9 are attached to the outer peripheral surface of the rotating shaft 7 to form a stirring blade group 10. Further, on the rear side in the advancing direction of the rotating shaft 7, a substantially rectangular guide plate 11 that is attached to the cover member 8 and is arranged parallel to the rotating shaft 7 and has a downward inclination from the front to the rear in the advancing direction is attached.

[0014] The rotating shaft 7 is connected to the base end portion of the rotating shaft 7 and the support rod 3. A power transmission member (not shown) is built in the support rod 3, and the rotating shaft 7 is rotatably connected in conjunction with the power of the drive unit 2. Therefore, the rotational speed of the rotating shaft 7 can be changed according to the change in the strength of the power of the drive unit 2.

[0015] Furthermore, a group of stirring blades 10, consisting of multiple stirring blades 9, is formed on the outer circumferential surface of the rotating shaft 7. The stirring blades 9 are roughly rectangular plates with a slight thickness and are mounted at intervals in the axial direction of the rotating shaft 7 (see Figure 2). In this embodiment, the longitudinal length of the stirring blades 9 is approximately 60 mm, and as shown in Figure 2, it is possible to stir the concrete to a depth of approximately 30 mm from the surface. Note that the longitudinal length of the stirring blades 9 is not limited to approximately 60 mm and can be appropriately changed according to the desired stirring depth.

[0016] As can be seen from Figure 2, the stirring blades 9 are mounted so that adjacent stirring blades 9 intersect on the rotation shaft 7. Each stirring blade 9 is configured to be inclined with respect to the axial direction of the rotation shaft 7, and in this embodiment, each stirring blade 9 is configured to be inclined at an angle of approximately 60 degrees with respect to the rotation shaft 7 (see Figure 2). This inclination allows for sufficient and efficient stirring of the concrete surface 13 to a predetermined depth, i.e., the concrete surface layer 12.

[0017] The guide plate 11 has a downward slope from the front to the rear in the direction of travel of the stirring device 1, and the rear lower end 14 of the downward slope is attached so as to be in contact with the concrete surface layer 12 (see Figure 1). When the stirring device 1 moves forward with the rear lower end 14 in contact with the concrete surface 13, it plays a role in smoothing the surface of the concrete surface layer 12 after it has been stirred and mixed by the stirring blade group 10.

[0018] Furthermore, as can be seen from Figures 2 and 3, the guide plate 11 is provided with a linear elongated opening 16 extending in the longitudinal direction, and an adjustment member 17 is provided on the rear side of the cover member 8 in the direction of travel, projecting perpendicularly to the guide plate 11.

[0019] The guide plate 11 is designed so that an adjustment member 17 protruding from the cover member 8 is inserted through the elongated opening 16, and a connector such as a nut is screwed onto the inserted adjustment member 17 to fix it in a predetermined position in the elongated opening 16. This is called the depth adjustment section 15.

[0020] As shown in Figure 4(b), the stirring blades 9 of the stirring blade group 10 are adjusted to be exposed from the lower end of the rear lower end 14. In other words, the length of the exposed stirring blades 9 becomes the stirring depth (depth L). The stirring depth can be appropriately changed by fixing the adjustment member 17 at any position in the elongated opening 16 of the guide plate 11. This is because the guide plate 11 can be moved up and down by the length of the opening 16, and the length of the stirring blade group 10 exposed from the lower end of the rear lower end 14, that is, the stirring depth, can be adjusted.

[0021] Therefore, by fixing the adjustment member 17 in the elongated opening 16 in the position where the rear lower end 14 of the guide plate 11 is in contact with the concrete surface 13 according to the stirring depth, the stirring blade group 10 can adjust the stirring depth and mix the concrete at a constant rate, and the guide plate 11 can smooth the concrete surface 13. The depth L is defined as the depth to which the stirring blade group 10 stirs, that is, the length to which the stirring blades 9 are inserted into the concrete surface layer 12 (see Figure 4(b)).

[0022] This allows the stirring depth to be easily adjusted by the stirring blade group 10, enabling uniform stirring of the concrete surface layer 12 to the desired depth.

[0023] Here, the elongated opening 16 is configured to have a straight opening length of approximately 50 mm. That is, the adjustment range of the depth length L of the stirring blade 9 can be adjusted from a depth of approximately 0 to 50 mm, with the concrete surface 13 being 0 mm. In this implementation, the depth length L is set to 30 mm, and the surface layer 12 of the concrete is stirred at a depth of 30 mm from the concrete surface 13. As shown in Figure 4(a), since reinforcing bars are embedded in the concrete structure, the stirring can be appropriately determined and performed according to the thickness from the concrete surface 13 to the cover portion of the reinforcing bars.

[0024] Furthermore, the stirring device 1 of the present invention is provided with a gripping portion 19 on the support rod 3, and the stirring unit 5 can be easily operated by gripping the gripping portion 19.

[0025] Next, a method for constructing the concrete surface layer 12 using the mixing device 1 of the present invention will be described with reference to Figures 4 and 5. Note that the mixing device 1 in Figure 4 is a simplified representation.

[0026] First, concrete is poured into the designated location (flow 100 in Figure 5), and the poured concrete is compacted using a vibrator or other vibrating device (flow 101 in Figure 5). Then, the top surface of the compacted concrete is leveled, that is, the concrete surface 13 is constructed to be horizontal and flat (flow 102 in Figure 5).

[0027] Subsequently, as can be seen from Figure 4(a), the setting accelerator 18 is uniformly sprinkled onto the flattened concrete surface 13 (flow 103 in Figure 5), and the mixture is stirred using the stirring device 1 so that the sprinkled setting accelerator 18 and the concrete surface layer 12 (cover portion) are thoroughly mixed (flow 104 in Figure 5).

[0028] The amount of setting accelerator 18 to be applied is adjusted as appropriate depending on the construction period, temperature, and the desired reduction in finishing time. As will be described later, in the quality evaluation of concrete using the construction method of the present invention, the amount of setting accelerator 18 applied is 200 g / m². 2 ~400g / m2 It has been confirmed that spraying this substance shortens the concrete's setting time (finishing time) by approximately 2 to 4 hours.

[0029] Here, the setting accelerator 18 used is one that is mainly composed of calcium nitrate, calcium nitrite, calcium chloride, aluminum sulfate, or lithium salt.

[0030] Furthermore, as described above, the stirring device 1 of the present invention is configured to stir the concrete surface layer 12 to a depth of about 30 mm from the concrete surface 13 (see Figure 4(a)). In other words, the multiple stirring blades 9 that form the stirring blade group 10 shown in Figure 2 rotate, thereby stirring the setting accelerator 18 and the concrete surface layer 12. Moreover, since the multiple stirring blades 9 are configured to be inclined at an angle of about 60 degrees with respect to the rotation axis 7, they can stir efficiently and sufficiently, and by stirring evenly up to the depth into which the multiple stirring blades 9 are inserted, variations in the setting time of the concrete surface layer 12 are less likely to occur.

[0031] After the aforementioned stirring, the setting of the concrete surface layer 12 is promoted, and then the concrete surface 13 is roughly leveled horizontally using a rough leveling tool such as a wooden trowel, a plastic trowel, or a rake (flow chart 105 in Figure 5). After that, the concrete surface layer 12 is left to set, but as mentioned above, this construction method can shorten the setting time (time until finishing work can be performed) by approximately 2 to 4 hours.

[0032] After confirming that the concrete surface layer 12 has set, in the final finishing stage, a troweling process is performed to make the concrete surface 13 horizontally flat using finishing tools such as a metal trowel or a mechanical trowel (flow chart 106 in Figure 5).

[0033] Next, the effect of shortening the setting time (finishing work time) and the evaluation results of concrete quality using the above construction method with the stirring device 1 of the present invention will be briefly explained with reference to the figures.

[0034] First, Figure 6 is a line graph showing the reduction in setting time (finishing time) when the setting accelerator 18 is added to the concrete surface layer 12. The horizontal axis of the graph represents the amount of setting accelerator 18 applied (g / m²). 2 The vertical axis represents the time saved during the finishing process.

[0035] Figure 6(a) shows the relationship between the amount of concrete sprayed and the finishing time when the curing temperature is 5°C and the concrete nominal strengths are 21, 30, and 45. Similarly, Figure 6(b) shows the relationship between the amount of concrete sprayed and the finishing time when the curing temperature is 10°C and the concrete nominal strengths are 21, 30, and 45.

[0036] From Figures 6(a) and 6(b), a setting accelerator 18 is applied to the concrete surface 13 at a rate of 200-400 g / m². 2 When applied, the setting time (finishing time) was shortened by approximately 2 to 4 hours. Furthermore, it was confirmed that a similar reduction in finishing time could be obtained with a constant application amount, regardless of concrete strength or curing temperature.

[0037] Next, Figure 7 is a graph comparing a test specimen in which the concrete nominal strength was set to 30 and the base concrete and the setting accelerator 18 were mixed throughout the concrete, with a test specimen in which the setting accelerator 18 was added to the concrete surface layer 12 from the concrete surface 13 to a depth of 30 mm using this construction method.

[0038] The horizontal axis shows the conditions for each test specimen, and the vertical axis shows the compressive strength of the concrete (N / mm²). 2 This shows the following. Here, we will briefly explain the meaning of the display configuration on the horizontal axis. F0 on the horizontal axis represents the state in which no setting accelerator 18 has been added, and F2 represents the addition rate (%) of setting accelerator 18 to the amount of cement, which is 2% by weight, i.e., 200g / m of setting accelerator 18. 2This indicates a state where a considerable amount has been added. Furthermore, S represents the state in which the setting accelerator 18 has been mixed into the entire concrete, T30 represents the state in which the setting accelerator 18 has been mixed into the concrete surface layer 12 up to 30 mm from the concrete surface, and C represents the state in which core samples have been taken from each test specimen (with varying addition rates of setting accelerator 18) prepared by the construction method of the present invention.

[0039] These results confirmed that when the setting accelerator 18 is added to the concrete surface 13 to 30 mm, the compressive strength of the concrete is equivalent to that of the base concrete ("30-F0-S" in Figure 7). Furthermore, in test specimens in which the setting accelerator 18 was mixed throughout the entire concrete, the compressive strength tended to increase as the amount of setting accelerator 18 added increased. However, when the setting accelerator 18 was added only to the surface layer 12 of the concrete, no significant change in the compressive strength of the concrete was observed.

[0040] Therefore, even when using the construction method of the present invention, in which the setting accelerator 18 is added only to the surface layer 12 of the concrete, the concrete structure exceeds the mix design strength and mix design strength × 0.7, which are the strength standards that the concrete structure should possess. Thus, it was confirmed that there is no impact on the concrete quality, particularly the concrete strength and durability.

[0041] As described above, the construction method of the present invention adds the setting accelerator 18 only to the surface layer 12 of the concrete, thus reducing the amount of setting accelerator 18 used compared to conventional techniques in which the setting accelerator 18 is added to the entire concrete. Therefore, it is possible to significantly reduce construction costs and shorten the finishing time (setting time).

[0042] In addition, since the concrete surface layer 12 can be thoroughly and uniformly mixed using the mixing device 1 of the present invention, there is no need to mix using an agitator truck or mixer as in the conventional method, and the high level of convenience is one of the features of the present invention. [Industrial applicability]

[0043] In the above embodiment, the effect of reducing construction costs and shortening construction time by accelerating the setting of the concrete surface layer 12 using a setting accelerator 18 is described as an example of implementation. However, this construction method can be applied not only to accelerating setting but also to improving the quality of the concrete surface layer 12. [Explanation of Symbols]

[0044] 1. Stirring device 2 Drive unit 3 Support rod 4 Control lever 5. Stirring section 6. Power Department 7 Rotation axis 8 Cover component 9. Agitator blade 10 Agitation blade group 11 Guide plate 12. Concrete surface layer 13 Concrete surface 14 Lower rear end 15 Depth adjustment section 16 Open elongated holes 17 Adjustment Member 18 Set accelerator 19 Gripping part L depth length

Claims

1. The stirring device comprises a drive member, a rotating shaft that rotates in conjunction with the drive member and extends horizontally from its base end, a group of stirring blades attached to the outer surface of the rotating shaft and rotating axially in accordance with the rotation of the rotating shaft, and a guide plate that extends horizontally from the base end, is provided parallel to the rotating shaft, and is located on the rear side of the rotating shaft in the direction of travel. The aforementioned stirring blade group is composed of a plurality of stirring blades, and these plurality of stirring blades are mounted at intervals in the axial direction of the rotation shaft, so that adjacent stirring blades intersect on the rotation shaft. The stirring blade is configured to be inclined with respect to the axial direction, and when the stirring blade rotates, it can stir the concrete poured in concrete work from the surface to a predetermined depth. The guide plate has a downward slope from the front to the rear in the direction of travel of the stirring device, and the lower rear end of the downward slope is configured to contact the surface layer of the concrete after stirring. As the stirring device moves forward in the direction of travel while in contact, the surface layer of the concrete after stirring can be made smooth. A concrete surface layer stirring device characterized by the following features.

2. The guide plate has a depth adjustment section that adjusts the depth from the concrete surface to which the stirring blade group stirs, The depth adjustment unit adjusts the depth to which the stirring blades are inserted from the concrete surface to a predetermined depth for stirring, and the rear lower end of the guide plate is fixed at the adjusted predetermined depth. The concrete surface layer stirring device according to claim 1.

3. The aforementioned stirring device is equipped with a handle for carrying, and can be operated by gripping the handle. A concrete surface layer stirring device according to claim 1 or 2.

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