Concrete compaction method, concrete compaction device, and needle attachment for concrete compaction device

Abstract

To provide a concrete compaction method, a concrete compaction device and a needle attachment for the concrete compaction device that can improve mechanical properties without causing a significant decrease in work efficiency.SOLUTION: The present invention includes manufacturing step S1 for manufacturing a laminate using a cementitious material, needle insertion step S2 for inserting a plurality of needles into the laminate from a direction perpendicular to the interlayer plane of the laminate, and vibration step S3 for applying vibration to the plurality of needles while the plurality of needles is inserted into the laminate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a concrete compaction method for compacting a cement-based laminate produced by a 3D printer, a concrete compaction device, and a needle attachment used in the concrete compaction device. [Background technology]

[0002] In recent years, the development of 3D printing technology for cement-based materials has been progressing in the construction field as well. One of these 3D printing technologies is a construction concrete 3D printer (hereafter, construction 3D printer), which ejects and layers highly thixotropic cement-based materials. Construction 3D printers are expected to have various advantages, such as time reduction, cost reduction, labor saving, labor saving, 24-hour construction, and improved safety by automating dangerous work, so research on them is becoming more and more active. Problems with laminates created by construction 3D printers include the presence of discontinuous layers such as cold joints between layers, the presence of large voids between layers, and the resulting reduction in strength.

[0003] To address this issue, Non-Patent Document 1 describes embedding metal fibers between layers to suppress the decrease in strength due to discontinuous layers. However, as described in the conclusion of Non-Patent Document 1, if the metal fibers are not inserted appropriately, voids may be generated around the metal fibers, which may lead to a decrease in mechanical properties. In response to the above problem, Patent Document 1 describes a method for manufacturing a laminated structure by stacking cement-based materials, which is characterized by having a step of providing a retarder between layers, the retarder having a set retarding performance that delays the setting time of the cement-based material. However, when this technology is applied to a material extrusion (ME) type additive manufacturing device (construction 3D printer), the construction 3D printer needs to temporarily stop the material being continuously extruded from the nozzle and spray the set retarder, etc. This could lead to a significant decrease in work efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-119360 A [Non-patent literature]

[0005] [Non-Patent Document 1] Masayoshi Miyata, Tomoya Nishiwaki, Shoko Furue, and Tsuyoshi Fukatsu, "Fundamental Study on Interlayer Reinforcement of Laminated Structures Using a Concrete 3D Printer for Construction," Proceedings of the Japan Concrete Institute, 2020, Vol. 42, No. 1, pp. 1888-1893. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a concrete compaction method, a concrete compaction device, and a needle attachment for a concrete compaction device that can improve mechanical properties without significantly reducing work efficiency. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following means. The present invention includes a manufacturing process for producing a laminate using a cement-based material, a needle insertion process for inserting a plurality of needles into the laminate from a direction perpendicular to the interlayer surface of the laminate, and a vibration process for applying vibrations to the plurality of needles while they are inserted into the laminate. The present invention also provides a concrete compaction device for compacting a laminate made of cement-based materials, the device comprising: a vibrator that generates vibrations; a fixed plate that is fixed to the vibrator on one side; and a plurality of needles that are fixed to the other side of the fixed plate. A magnet is fixed to the one surface of the fixed plate facing the vibrator, and the vibrator and the fixed plate are fixed to each other by the magnet. It was decided to do so. The present invention also provides a needle attachment for use in a concrete compaction device that compacts a laminate made of cement-based materials, the needle attachment comprising: a fixed plate having one surface fixed to a vibrator provided in the concrete compaction device; and a plurality of needles fixed to the other surface of the fixed plate. A magnet is fixed to the one surface of the fixed plate facing the vibrator, and the vibrator and the fixed plate are fixed to each other by the magnet. It was decided to do so.

[0008] The concrete compaction method, concrete compaction device, and needle attachment for a concrete compaction device of the present invention can insert needles into a laminate of cement-based materials from a direction perpendicular to the interlaminar surface of the laminate, and vibrate the multiple needles. This is thought to result in at least a portion of the interlaminar layers of the laminate being integrated with each other. It is also thought that as the needles are inserted, a portion of one of the interfaces that contact each other is dug into a portion of the other interface, thereby exerting a spike function. It is thought that by obtaining at least one of these effects, the mechanical properties of the laminate of cement-based materials, such as the splitting tensile strength, are improved. In addition, since the multiple needles are inserted from a direction perpendicular to the interlaminar surface of the laminate, air is less likely to be entrained during insertion, and voids are less likely to be formed in the laminate. Furthermore, since the multiple needles are vibrated, it is thought that the air in the laminate can be expelled, thereby improving the density. Therefore, it is thought that these effects also improve the mechanical properties of the laminate of cement-based materials. In addition, a magnet is fixed to one side of the fixed plate facing the vibrator, and the vibrator and the fixed plate are fixed together by the magnet, so that the vibrator and the fixed plate can be fixed together in an appropriate and detachable manner. Furthermore, the laminate produced in the manufacturing process is made by stacking multiple layers of cement-based materials, and the needle insertion process and vibration process involve treating the laminate made up of multiple stacked layers with a needle attachment, so there is less of a decrease in work efficiency compared to when a setting retarder is provided between each layer or when metal fibers are buried between the layers.

[0009] In the manufacturing process, it is preferable to manufacture the laminate using a material extrusion type additive manufacturing device, which can suitably manufacture the laminate. It is preferable that the distance D between the needles in the plurality of needles and the extrusion width W of the cementitious material satisfy D < W. By doing so, vibration can be surely applied between the layers of the laminate formed of the cementitious material extruded from the nozzle. Therefore, the effect of improving the mechanical properties of the laminate of the cementitious material can be surely obtained.

[0010] The vibration in the vibration step or the vibration generated by the vibrator is a vertical vibration, and the vibration is performed under the conditions of a maximum acceleration of 90 to 139 m / s 2 , a vibration amplitude of 0.2 to 0.4 mm, a frequency of 80 to 120 Hz, and 10 to 30 seconds. Here, the "vertical direction" in this specification refers to the direction perpendicular to the base when forming a laminate in which the number of layers increases in a direction away from the base ground, wall surface, etc. by the construction 3D printer. Note that the "horizontal direction" in this specification refers to the direction parallel to the base when forming a laminate in which the number of layers increases in a direction away from the base ground, wall surface, etc. by the construction 3D printer. When vibration is performed under the above-described conditions, the vertical vibration acts on the layers between the directions perpendicular to the vertical vibration, improving the integrity between the layers. Therefore, the mechanical properties of the laminate can be surely improved. 。

Advantages of the Invention

[0011] The concrete compaction method, the concrete compaction device, and the needle attachment for the concrete compaction device of the present invention can improve the mechanical properties without causing a significant decrease in work efficiency.

Brief Description of the Drawings

[0012] [Figure 1] It is a flowchart showing the content of the concrete compaction method according to an embodiment of the present invention. [Diagram 2] It is a perspective view showing the configuration of the concrete compaction device according to an embodiment of the present invention. [Diagram 3]1 is a plan view showing the configuration of a concrete compaction device according to one embodiment of the present invention. [Figure 4] 1 is a front view showing the configuration of a concrete compaction device according to one embodiment of the present invention. [Diagram 5] 1 is a side view showing the configuration of a concrete compaction device according to one embodiment of the present invention. [Figure 6] 1 is a perspective view of a needle attachment according to an embodiment of the present invention, viewed from one side of a fixed plate. FIG. [Figure 7] 13 is a perspective view of the needle attachment according to one embodiment of the present invention, seen from the other side of the fixed plate. FIG. [Figure 8] FIG. 13 is a schematic diagram illustrating the manner in which the needle is inserted and vibrated in the first test. [Figure 9] FIG. 1 is a schematic diagram showing the relationship between the arrangement of core specimens and the direction of application of pressing force in the first splitting tensile strength test. [Figure 10] 1 is a graph showing the splitting tensile strength (N / mm 2 ) of laminates according to Examples 1 to 4, Comparative Examples 1 and 2, and Reference Example 1. [Figure 11] FIG. 1 is a perspective view of a portion of the test material prepared in the second test, viewed from above and obliquely. [Figure 12] FIG. 1 is a perspective view of the test material prepared in the second test, seen from the side and obliquely. [Figure 13] FIG. 13 is a schematic diagram showing the relationship between the arrangement of core specimens and the direction of application of pressing force in the second test of splitting tensile strength test. [Figure 14] 1 is a graph showing the average splitting tensile strength (N / mm2) of laminates according to Reference Example 2, Comparative Example 3, and Examples 5 and 6, in which the core specimens were pulled from the top. [Figure 15] 1 is a graph showing the average splitting tensile strength (N / mm2) of laminates according to Reference Example 3, Comparative Example 4, and Examples 7 and 8, in which the core specimens were drawn horizontally. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the description of each embodiment, the same components are denoted by the same names and symbols, and duplicate descriptions may be omitted.

[0014] [Concrete compaction method] First, with reference to FIG. 1, one embodiment of a concrete compaction method according to the present invention (hereinafter, sometimes simply referred to as "the method") will be described. Fig. 1 is a flow chart showing the details of a concrete compaction method according to an embodiment of the present invention. As shown in Fig. 1, the method includes a manufacturing step S1, a needle insertion step S2, and a vibration step S3.

[0015] (Manufacturing process S1) The manufacturing process S1 is a process for manufacturing a laminated body using a cement-based material. The cement-based material refers to an inorganic bonding agent for civil engineering and construction that contains lime as a main component and hardens by reacting with water. An example of a cement-based material is concrete. Concrete generally refers to a mixture of cement, fine aggregate (e.g., sand), coarse aggregate (e.g., gravel) and water, and various admixtures can be mixed as necessary. In this embodiment, it is preferable to use a cement-based material (concrete) for a construction 3D printer in which the thixotropy has been increased by mixing an admixture. Here, the thixotropy can also be increased by adjusting the water-cement ratio. Note that the cement-based material that can be used in this embodiment is not limited to the above-mentioned materials, and for example, a cement paste, mortar, etc. having high thixotropy can be used. Here, the cement paste refers to a mixture of cement and water. The mortar refers to a mixture of cement and fine aggregate with water. Various admixtures can be mixed into the cement paste and mortar. Any fiber can be added to the cement-based material. For example, vinylon fiber having a length of 15 mm and a diameter of 0.3 mm can be used, but is not limited to this. The amount of fiber added can be, for example, 2.5 vol% or the like, but is not limited to this.

[0016] In the manufacturing process S1, it is preferable to manufacture the laminate using an additive manufacturing apparatus of the material extrusion method, that is, the above-described construction 3D printer. By doing so, the laminate can be suitably manufactured. The construction 3D printer is provided with a nozzle having a predetermined opening width, and discharges a cement-based material from the nozzle.

[0017] (Needle insertion step S2) The needle insertion step S2 is a step of inserting a plurality of needles into the laminate from a direction orthogonal to the surface between the layers of the laminate manufactured in the manufacturing step S1. In the needle insertion step S2, the needle is inserted into the laminate of the cement-based material from a direction orthogonal to the surface between the layers of the laminate (that is, for example, the needle is inserted at a right angle to the surface between the layers). Therefore, it is difficult to entrain air when inserting the needle. Further, it is considered that a spike function is exhibited when a part of one interface in contact with each other is dug into a part of the other interface as the needle is inserted. Thereby, it is considered that the mechanical properties of the laminate of the cement-based material are improved. Examples of the mechanical properties include splitting tensile strength. In the present embodiment, the needle is a metal rod-shaped body having a particle size (5 mm) or less of fine aggregate, for example, a metal rod-shaped body having a diameter of 0.5 to 4 mm, preferably a diameter of 1 to 2 mm. The length of the needle can be arbitrarily set, but for example, it is 5 to 20 cm, preferably 5 to 15 cm, more preferably 6 to 10 cm, and in the example, it is 7 cm.

[0018] It is preferable that the distance D between the needles and the extrusion width W of the cement-based material in the plurality of needles satisfy D <W. By doing so, vibration can be surely applied to the layers between the layers of the laminate formed of the cement-based material extruded from the nozzle. Therefore, the effect of improving the mechanical properties of the laminate of the cement-based material described above can be surely obtained. In addition, the above-described distance D and extrusion width W can also be set such that D:W is 1:1 to 2. Even in this case, vibration can be surely applied to the layers between the layers of the laminate formed of the cement-based material extruded from the nozzle. Therefore, the effect of improving the mechanical properties of the laminate of the cement-based material described above can be surely obtained.

[0019] The distance D between the needles can be, for example, 25 mm or 50 mm, but is not limited thereto. In this example, the distance D between the needles can be 25 mm, and the extrusion width W of the cement-based material can be 25 to 50 mm, reflecting the conditions such as the ratio. The distance D between the needles can be 50 mm, and the extrusion width W of the cement-based material can be 50 to 100 mm. The conditions such as the ratio described above are only one embodiment, and other embodiments are also possible. For example, when the distance D between the needles is 50 mm, the extrusion width W of the cement-based material can be more than 100 mm. The insertion of multiple needles into the stack and the application of vibrations can be accomplished with a concrete compaction device, which is described below.

[0020] (Vibration process S3) The vibration step S3 is a step of applying vibration to the needles inserted in the needle insertion step S2 while they are still inserted in the laminate. It is believed that the application of vibration creates a portion where the layers are integrated with each other at least in a part of the space between the layers of the laminate (for example, around the needles that penetrate the spaces between the layers). This is believed to improve the mechanical properties of the laminate of cement-based materials. In addition, since the needles are vibrated, it is believed that the air in the laminate can be expelled, thereby improving the density. The vibration step S3 may be performed simultaneously with the needle insertion step S2. That is, the needle may be inserted into the laminate while being vibrated. The needle may also be removed from the laminate while being vibrated. This can prevent the occurrence of voids when inserting and removing the needle.

[0021] The vibration in the vibration step S3 is in the vertical direction, and the maximum acceleration is, for example, 90 to 139 m / s 2It is preferable to perform vibration under the conditions of a vibration amplitude of 0.2 to 0.4 mm and a frequency of 80 to 120 Hz for 10 to 30 seconds. In this way, since the vibration conditions are appropriate, the vertical vibration acts on the layers in a direction perpendicular to the vertical vibration, improving the integrity of the layers, and therefore the mechanical properties of the laminate can be reliably improved. The maximum acceleration is, for example, 99 m / s 2 or 111 m / s 2 or 133 m / s 2 The vibration amplitude can be, for example, 0.3 mm, the frequency can be, for example, 100 Hz, and the vibration time can be, for example, 20 seconds.

[0022] The vibration in the vibration step S3 can also be horizontal. In this case, the vibration conditions can be the same as those described above. In this way, the horizontal vibration acts on the layers in a direction perpendicular to the horizontal vibration, improving the integrity of the layers, thereby improving the mechanical properties of the laminate. Note that the horizontal vibration is preferably set to vibrate in a direction parallel to the width direction of the cementitious material extruded from the nozzle in order to more reliably apply the vibration effect to the layers.

[0023] The needle insertion step S2 and the vibration step S3 can be performed every time a predetermined number of layers are laminated in the manufacturing step S1. The number of layers can be appropriately set depending on the thickness of the layers and the length of the needle. For example, if the length of the needle is 7 cm and the thickness of one layer is 1 cm, it is recommended to perform one set of the needle insertion step S2 and the vibration step S3 every time five layers are formed in the manufacturing step S1. In this way, the needle insertion step S2 and the vibration step S3 can be performed in units of multiple layers, so that the work efficiency is unlikely to decrease. In this case, the tip of the needle can be protruded 1 cm from the bottom layer while securing a space of 1 cm thick between the fixing plate to which the needle is fixed and the upper surface of the laminate. Therefore, even in a laminate with a large number of layers, the needle can be inserted and vibrated into the upper surface of the laminate formed in the previous manufacturing step S1 to the vibration step S3 and the lower surface of the laminate laminated in the current manufacturing step S1. This makes it possible to integrate a part of these layers and to exhibit a spike function, thereby improving the mechanical properties of the laminate. In addition, a space of 1 cm thickness is secured between the plate on which the needles are fixed and the top surface of the stack, so that they do not come into contact with each other and the surface of the stack is not roughened. The longer the needles are, the more layers can be stacked, improving work efficiency.

[0024] [Concrete compaction equipment] Next, a concrete compaction device (hereinafter, sometimes simply referred to as "this device") 1 according to one embodiment of the present invention will be described with reference to Figs. 2 to 5. Fig. 2 is a perspective view showing the configuration of the present device 1. Fig. 3 is a plan view showing the configuration of the present device 1. Fig. 4 is a front view showing the configuration of the present device 1. Fig. 5 is a side view showing the configuration of the present device 1.

[0025] The present device 1 is a device for compacting a laminate LP made of cement-based materials. The present device 1 can be used as a device for compacting a specimen for a strength test. As shown in Figs. 2 to 5, the present device 1 includes a vibrator 2 that generates vibrations, a plate-shaped fixed plate 3 fixed to the vibrator 2 on one side, and a plurality of needles 4 fixed to the other side of the fixed plate 3. The present device 1 includes a stand 5. The stand 5 is formed of four columns, four horizontal members provided on the upper parts of the columns, and two horizontal members provided at the lower parts of the columns so as to face each other. The stand 5 includes a moving mechanism 51. The moving mechanism 51 includes at least one of a height direction (Z direction) moving mechanism 52 and a plane direction (Y direction) moving mechanism 53. Note that Figs. 2 to 5 show a state in which both the height direction moving mechanism 52 and the plane direction moving mechanism 53 are included. Although not shown, the stand 5 may be appropriately set according to the shape of the laminate LP. For example, the plane direction moving mechanism 53 may be movable in both the Y direction and the X direction. The stand 5 may also be a stand for a nozzle that stacks concrete.

[0026] The vibrator 2 is fixed to a moving mechanism 51, and the vibrator 2 can be freely moved in the height direction (Z direction) and planar direction (Y direction) of the device 1 by a height direction moving mechanism 52 and a planar direction moving mechanism 53. In the case of this device 1, the vibrator 2 is moved by the planar movement mechanism 53, so that the multiple needles 4 can be arranged on a predetermined position of the laminate LP, which is the object of compaction. Then, the height direction movement mechanism 52 moves the vibrator 2 and the multiple needles 4 fixed thereto downward, so that the multiple needles 4 can be inserted into the laminate LP so as to be perpendicular to the interlayer surface of the laminate LP. Thereafter, the vibrator 2 is operated, so that vibration can be applied to the multiple needles 4 in a state in which the multiple needles 4 are inserted into the laminate LP. After the application of vibration is completed, the device 1 moves the vibrator 2 and the multiple needles 4 fixed thereto upward by the height direction movement mechanism 52, so that the multiple needles 4 are pulled out from the laminate LP.

[0027] The vibration generated by the vibrator 2 is a vertical vibration, and the vibration is, for example, a maximum acceleration of 90 to 139 m / s 2Anything can be used as long as it can be generated under the conditions of an amplitude of 0.2 to 0.4 mm, a frequency of 80 to 120 Hz, and for 10 to 30 seconds. Note that the vibrator 2 is not limited to the one described above, and any device can be used as long as it can improve the mechanical properties of cement-based materials (e.g., concrete).

[0028] In this apparatus 1, it is preferable that the distance D between the needles 4 among the plurality of needles 4 and the extrusion width W of the cement-based material satisfy D < W. By doing so, vibration can be surely applied between the layers of the laminate LP formed of the cement-based material extruded from the nozzle. Therefore, the effect of improving the mechanical properties of the laminate LP of the cement-based material described above can be surely obtained. Note that the above-described distance D and extrusion width W can also be set such that D:W is 1:1 to 2. Even in this case, vibration can be surely applied between the layers of the laminate LP formed of the cement-based material extruded from the nozzle. Therefore, the effect of improving the mechanical properties of the laminate LP of the cement-based material described above can be surely obtained.

[0029] Note that the extrusion width W is the same dimension as the discharge port of the nozzle of the construction 3D printer, but may increase or decrease depending on the extrusion pressure / flow rate of the cement-based material from the nozzle and the physical properties of the cement-based material. As described above, the distance D between the needles 4 can be, for example, 25 mm or 50 mm. In the case of this example, reflecting the conditions such as the ratio, the distance D between the needles 4 can be 25 mm, and the extrusion width W of the cement-based material can be 25 to 50 mm. Also, the distance D between the needles 4 can be 50 mm, and the extrusion width W of the cement-based material can be 50 to 100 mm. The conditions such as the ratio described above are only one aspect, and other aspects are also possible. For example, when the distance D between the needles 4 is 50 mm, the extrusion width W of the cement-based material can be more than 100 mm. The number of the plurality of needles 4 can be, for example, 16, but is not limited thereto and can be arbitrarily set. The multiple needles 4 can be fixed to the fixed plate 3, for example, by inserting the needles 4 into holes for fixing the needles provided in the fixed plate 3 and crimping the holes.

[0030] The fixing plate 3 and the vibrator 2 can be fixed by fixing a magnet 6 (see FIG. 6) to one side of the fixing plate 3 and utilizing the magnetic attraction of the magnet 6. In this case, the magnetic attraction of the magnet 6 can be, for example, 784N (80kgf). In this way, even if the vibration under the above conditions is applied, the vibration can be suitably transmitted to the laminate LP without causing the fixing plate 3 and the plurality of needles 4 to fall off. The fixing of the fixing plate 3 and the vibrator 2 is not limited to this, and they can be fixed using, for example, a cable tie or the like, or in combination. Examples of the material of the needles 4 include high-speed tool steel materials specified in JIS G 4403:2015, specifically SKH51, etc. Examples of the material of the fixing plate 3 include aluminum alloy plates specified in JIS H 4000:2014, specifically A2017, etc. The materials of the needles 4 and the fixing plate 3 are not limited to those described above.

[0031] [Needle attachment] Next, one embodiment of a needle attachment for a concrete compaction device (hereinafter, sometimes simply referred to as a "needle attachment") A according to the present invention will be described with reference to Figs. 6 and 7. Fig. 6 is a perspective view of a needle attachment A according to one embodiment of the present invention, as viewed from one surface 3a of a fixed plate 3. Fig. 7 is a perspective view of a needle attachment A according to one embodiment of the present invention, as viewed from the other surface 3b of a fixed plate 3. The needle attachment A according to this embodiment is attached to the above-mentioned concrete compaction device (the device 1) when in use. Specifically, it is attached to the vibrator 2 of the device 1 when in use.

[0032] As shown in Fig. 6, the needle attachment A has a plate-shaped fixed plate 3. The magnet 6 described above is fixed to one surface 3a of the fixed plate 3, which allows the needle attachment A to be detachably attached to the vibrator 2. Although not shown, the vibrator 2 is provided with an iron member to which the magnet 6 can be attracted, or a magnet that attracts the magnet 6, at a position facing the magnet 6. This allows the needle attachment A and the vibrator 2 to be firmly and accurately fixed.

[0033] 7, needle attachment A has multiple needles 4 fixed to the other surface 3b of fixing plate 3. The magnet 6 is fixed by magnet fixing screws 6a from the other surface 3b of fixing plate 3. Fixing magnet 6 in this manner prevents the screws from loosening due to vibration from vibrator 2, and the magnet 6 and magnet fixing screws 6a from falling off. It should be noted that the needle attachment A does not need to include the magnet 6 or the magnet fixing screw 6a, so long as it can be detachably attached to the vibrator 2 by other means.

[0034] The above-described method, device 1, and needle attachment A can insert needles 4 into the laminate LP of cement-based materials from a direction perpendicular to the interlaminar surface of the laminate LP, and vibrate the multiple needles 4. This is believed to result in at least a portion of the interlaminar layers of the laminate LP being integrated with each other (improved integration). It is also believed that as the needles 4 are inserted, a portion of one interface that is in contact with the other interface is dug into a portion of the other interface, thereby exerting a spike function. It is believed that the mechanical properties of the laminate LP of cement-based materials, such as splitting tensile strength, are improved by obtaining at least one of these effects. The method, device 1, and needle attachment A can insert needles 4 into the laminate LP after forming multiple layers and apply vibration, so that the work efficiency is less likely to decrease compared to the case where a setting retarder is provided between layers for each layer or where metal fibers are embedded between layers. In addition, the device 1 and needle attachment A do not embed metal fibers between layers, so air is not entrained when the metal fibers are embedded, and the strength is less likely to decrease. EXAMPLES

[0035] Next, the concrete compaction method, the concrete compaction device, and the needle attachment for the concrete compaction device according to the present invention will be specifically described with reference to examples and comparative examples.

[0036] [1] Test 1 In the first test, the needle was inserted and vibrated on a test material consisting of two layers, an upper layer and a lower layer. The test material used in the first test was made using cement-based materials for construction 3D printers with the mix shown in Table 1. In Table 1, P indicates the binder. This binder is a fast-hardening cement with enhanced initial reactivity. W indicates water. S1 and S2 indicate fine aggregates. Specifically, S1 indicates crushed sand, S2 indicates fine powder, and V indicates a separation reducing agent. The maximum particle size of the crushed sand (S1) is 2 mm, and the fine powder (S2) has a specific surface area of ​​8000 cm. 2 Very fine particles of about 1 / g were used.

[0037] [Table 1]

[0038] In the first test, a biaxial forced mixer was used to dry mix the binder, fine aggregate, and separation reducing agent shown in Table 1 at low speed for 15 seconds, and water was poured in. The mixture was then mixed at low speed for 2 minutes, scraped off, and then mixed at low speed for another 2 minutes. The volume of the mixed concrete, i.e., the amount of the mixture, was 9 liters. As shown in Table 1, no fiber was added.

[0039] The lower layer of the specimen was formed from the cementitious material produced as described above (5 cm thick), and after 10 or 20 minutes, the upper layer of the specimen was formed (5 cm thick), producing a two-layer specimen with a discontinuous surface (construction joint) between the lower and upper layers. For reference, a specimen without a construction joint was produced by forming the upper layer immediately after the formation of the lower layer (0 minutes). The age of the specimen was 7 days.

[0040] Using the present device 1 shown in Figures 2 to 5, vertical vibrations were applied to the test specimens using the needle 4 under various conditions shown in Table 2 below, and then the mechanical properties were measured. The vibration frequency of the needle 4 was always 100 Hz. In Table 2, "-" indicates that the needle 4 was not inserted and vibration was not performed. The vibration of the needle 4 was applied by exchanging the needle attachment A (Fig. 6, Fig. 7) with the needle 4 diameter of 1 mm and length of 7 cm and the needle attachment A (Fig. 6, Fig. 7) with the needle 4 diameter of 2 mm and length of 7 cm according to the conditions. The needle attachment A has the needle 4 made of high-speed tool steel (SKH51) specified in JIS G 4403:2015 fixed to the fixed plate 3 made of aluminum alloy plate (A2017 specified in JIS H 4000). The needle 4 was fixed to the fixed plate 3 by inserting the needle 4 into a hole formed in the fixed plate 3 and crimping it. The needle attachment A was detachably fixed to the vibrator 2 by the magnet 6 (maximum magnetic attraction force 784 N (80 kgf)) fixed to one surface 3a of the fixed plate 3. In this experiment, the needle attachment A was fixed to the vibrator 2 using a cable tie together with the magnet 6. The fixed plate 3 is a plate of 100×100×86 mm, and has a total of 16 needles 4 fixed to the other surface 3b at intervals of 2.5 cm both vertically and horizontally.

[0041] As mentioned above, the length of the needle 4 is 7 cm, so as shown in Fig. 8, a clearance of 1 cm is secured between the fixed plate 3 of the needle attachment A and the upper surface of the laminate LP to prevent direct contact between them. Therefore, the tip of the needle 4 is inserted 1 cm deep into the lower layer. Note that Fig. 8 is a schematic diagram explaining the insertion and vibration of the needle 4 in the first test. In Table 2, for the one with a vibration time of 10 seconds, needle 4 was used to vibrate vertically for 10 seconds, and then needle attachment A was moved completely and inserted into laminate LP so as not to overlap the location where needle 4 had vibrated previously, and the next vertical vibration was performed by needle 4. For the one with a vibration time of 20 seconds, needle 4 was used to vibrate vertically for 10 seconds, and then needle attachment A was moved and inserted into laminate LP so as to overlap half of the location where needle 4 had vibrated previously, and the next vertical vibration was performed by needle 4 for 10 seconds. As a result, for the one with a vibration time of 20 seconds, the vibration time is 20 seconds except for both ends.

[0042] As for the mechanical properties, as shown in Fig. 9, a cylindrical test piece (core specimen) with the joint surface as the maximum diameter was extracted from the test material, and a splitting tensile strength test was conducted to measure its strength. The splitting tensile strength test was conducted in accordance with JIS A 1108. In this test, as shown in Fig. 9, a pressing force was applied in a direction parallel to the joint surface of the core specimen (the direction of the arrow in Fig. 9) (performed with the vertical grain). Fig. 9 is a schematic diagram showing the relationship between the arrangement of the core specimen and the direction of the pressing force applied in the splitting tensile strength test of the first test. This test was performed with n=3 for each of Examples 1 to 4, Comparative Examples 1 and 2, and Reference Example 1 shown in Table 2, and the average was calculated. Table 2 shows the average splitting tensile strength together with the time from the formation of the lower layer to the formation of the upper layer, the needle diameter, and the conditions of the needle's vertical vibration.

[0043] [Table 2]

[0044] FIG. 10 shows the average values ​​of the splitting tensile strength (N / mm 2 ) is a graph showing As shown in FIG. 10, it was confirmed that Examples 1 to 3 had improved splitting tensile strength compared to Comparative Example 1, which had a construction joint surface under the same conditions. It was also confirmed that Example 4 had improved splitting tensile strength compared to Comparative Example 2, which had a construction joint surface under the same conditions. In this experiment, Example 2 had a splitting tensile strength equivalent to that of Reference Example 1, which did not have a construction joint surface. It is believed that the splitting tensile strength was improved by the improvement in the integrity of the upper and lower layers by vibration compaction, specifically, by improving the integrity between the upper and lower layers in the horizontal direction.

[0045] [2] Second Test In the second test, we investigated the case where needle insertion and vibration were performed on a specimen with an even larger number of layers. The test material used in the second test was made using the cementitious material for construction 3D printers with the composition shown in Table 3. W, P, S1, S2, and V in Table 3 are the same as those in Table 1. Vinylon fibers with a length of 15 mm and a diameter of 0.3 mm were used.

[0046] [Table 3]

[0047] The specimens in the second test were prepared using a material extrusion additive manufacturing device (construction 3D printer) described in a previously published paper (Tetsu Murata, Yukio Kinomura, Hirotoshi Oobi, and Yuto Yamamoto, "Development and Prospects of a New Concrete Construction Method Using 3D Printer Technology," Taisei Corporation Technology Center Report, No. 51, pp. 23-1 to 23-6, 2018). Here, the nozzle width of the construction 3D printer was 25 mm. The nozzle of the construction 3D printer was moved in the XYZ directions according to a preset sequence to extrude the cementitious material and prepare a test material consisting of a laminate. In preparing the test material, compaction was performed in the same manner as in the first test, that is, the insertion of the needle 4 and the application of vertical vibration every 5 layers (every 50 mm). The distance between the needles 4 was 25 mm, the same as the nozzle width (= extrusion width) of the construction 3D printer. In order to confirm the shape retention performance due to vibration, the deformation was measured three-dimensionally using optical 3D deformation analysis (ARAMIS). The age of the test material was 7 days. For reference, a test material was prepared by tamping instead of inserting the needle 4 and applying vertical vibration. The tamping was performed in accordance with JIS A 1132.

[0048] Figure 11 is a perspective view of a part of the test material prepared in the second test, seen from above and at an angle. Figure 12 is a perspective view of the test material prepared in the second test, seen from the side and at an angle. The dimensions of the test material were varied depending on the direction of extraction of the core specimen. The circular dotted lines in Figures 11 and 12 indicate the position of the core specimen to be extracted from the test material, and the core specimen was extracted in a cylindrical shape at that position.

[0049] The dimensions of the core specimen extracted from above (top extraction) (see Figure 11) were W225mm x B610mm x H130mm. Since this specimen was 130mm high, the needle was inserted three times in the height direction to compact it, every 50mm of the pile (finally after 30mm of the pile). This was done in three places in the horizontal direction at a specified interval (80mm). Then, a cylindrical core specimen (100mm in diameter) was extracted from the compacted area. In other words, three core specimens (n=3) were extracted from one specimen. The dimensions of the core specimen (see Figure 12) extracted from the side (horizontal extraction) were W175mm x B610mm x H230mm. Since this specimen was 230mm high, the needle was inserted five times in the height direction to compact it, every 50mm of the pile (finally after 30mm of the pile). This was done in three places in the horizontal direction at a specified interval (80mm). Then, a cylindrical core specimen (100mm in diameter) was extracted from the compacted area. In other words, three core specimens (n=3) were extracted from one specimen. Both ends of the extracted core specimens were polished to a height of 110 mm.

[0050] Then, in the same manner as in the first test, a splitting tensile strength test (based on JIS A 1108) was conducted to measure the mechanical properties, and the average was calculated. However, in this test, the pressing force was applied in a direction parallel to the joint surface (between layers) of the core specimen (direction of the arrow in Fig. 13) (performed with the grain vertically), as shown in Fig. 13. Note that Fig. 13 is a schematic diagram showing the relationship between the arrangement of the core specimens and the direction of the pressing force application in the splitting tensile strength test of the second test. The preparation conditions of the specimens in the second test for Examples 5 to 8, Comparative Examples 3 and 4, and Reference Examples 2 and 3 (conditions for application of vibration or compaction to the laminate, and for vertical vibration of the needle), the extraction direction of the core specimens, and the average values ​​of the splitting tensile strength are shown in Table 4. Note that "-" in Table 4 indicates that vibration was not applied or that there is no corresponding value because vibration was not applied.

[0051] [Table 4]

[0052] FIG. 14 shows the average value of the splitting tensile strength (N / mm 2 15 is a graph showing the average value of the splitting tensile strength (N / mm 214 and 15 are graphs showing the average values ​​of the splitting tensile strength.

[0053] As shown in Fig. 14, it was confirmed that Examples 5 and 6 had improved splitting tensile strength compared to Comparative Example 3, which had the same conditions for the joint surface (interlayer). Example 6 had a splitting tensile strength equivalent to that of Reference Example 2, in which the laminate was produced by tamping.

[0054] 15, it was confirmed that Example 8 had improved splitting tensile strength compared to Comparative Example 4 having the same conditions for the joint surface (interlayer). Example 8 had a splitting tensile strength equivalent to that of Reference Example 3, in which the laminate was produced by tamping. In this experiment, Example 8 had a splitting tensile strength exceeding that of Reference Example 3.

[0055] Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments and examples, and each of the above-described components can be appropriately modified without departing from the spirit of the present invention. [Explanation of symbols]

[0056] S1 Manufacturing process S2 Needle insertion process S3 Vibration process 1 Concrete compaction device (main device) 2 Vibrator 3 Fixed plate 3a One side 3b The other side 4 needles 5 Mounting 51 Moving mechanism 52 Height movement mechanism 53 Planar direction movement mechanism 6. Magnets A Needle Attachment LP laminate

Claims

1. A manufacturing process for manufacturing a laminate using a cement-based material; a needle insertion step of inserting a plurality of needles into the laminate in a direction perpendicular to a surface between the layers of the laminate; a vibration step of applying vibration to the plurality of needles while the plurality of needles is inserted into the laminate; A method for compacting concrete comprising the steps of:

2. 2. The method of claim 1, wherein the laminate is manufactured using a material extrusion type additive manufacturing device in the manufacturing process.

3. 3. The method for compacting concrete according to claim 1, wherein the distance D between the needles in the plurality of needles and the extrusion width W of the cement-based material are D<W.

4. The vibration in the vibration step is a vertical vibration, and the maximum acceleration is 90 to 139 m / s ２ The method for compacting concrete according to any one of claims 1 to 3, characterized in that the method is carried out under conditions of a vibration amplitude of 0.2 to 0.4 mm, a frequency of 80 to 120 Hz, and a duration of 10 to 30 seconds.

5. A concrete compaction device for compacting a laminate made of cement-based materials, comprising: A vibrator that generates vibrations; A fixing plate fixed to the vibrator on one surface thereof; A plurality of needles fixed to the other surface of the fixing plate; Equipped with The fixed plate has a magnet fixed to the one surface facing the vibrator, The vibrator and the fixed plate are fixed by the magnet. A concrete compaction device characterized by:

6. The vibration generated by the vibrator is a vertical vibration, and the maximum acceleration is 90 to 139 m / s ２ 6. The concrete compaction device according to claim 5, characterized in that the vibration is performed under conditions of a vibration amplitude of 0.2 to 0.4 mm, a frequency of 80 to 120 Hz, and a duration of 10 to 30 seconds.

7. 7. The concrete compaction device according to claim 5, wherein the distance D between the needles in the plurality of needles and the extrusion width W of the cement-based material are such that D<W.

8. A needle attachment for use with a concrete compaction device for compacting a laminate made of cement-based materials, comprising: A fixed plate having one surface fixed to a vibrator provided in the concrete compaction device; A plurality of needles fixed to the other surface of the fixing plate; Equipped with The fixed plate has a magnet fixed to the one surface facing the vibrator, The vibrator and the fixed plate are fixed by the magnet. A needle attachment for a concrete compaction device.

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