How to build it

Abstract

To provide a cement based spraying material that achieves enhanced self-standing capability subsequent to spraying and can forcibly be conveyed efficiently, and a construction method.SOLUTION: The cement based spraying material according to an embodiment of the present invention, is a cement based spraying material M to be sprayed to an object, i.e., a core material 11, and comprises cement, fine aggregate in an amount of not less than 80 pts.wt. and not more than 200 pts.wt. relative to 100 pts.wt. of cement, water in an amount of not more than 30 pts.wt. relative to 100 pts.wt. of cement, and air in a volume ratio of not higher than 40% relative to the total volume of cement, fine aggregate and water having been thoroughly blended.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a cement-based sprayed material and a construction method for constructing a structure using the cement-based sprayed material. [Background technology]

[0002] Conventionally, various cement-based materials have been known. JP 2008-239384 A describes a thick spray mortar. The thick spray mortar is used to reinforce or repair concrete structures. For example, the thick spray mortar is used in a repair or reinforcement method for deterioration of concrete structures, specifically, in a repair and reinforcement method for viaducts such as railways or roads, or tunnels.

[0003] The thickening mortar for spraying is composed of a combination of an anionic surfactant and a shrinkage reducing agent. This makes it unnecessary to add a thickener and / or an antifoaming agent. The thickening mortar for spraying contains 100 to 300 parts by weight of fine aggregate, 0.1 to 10 parts by weight of a sulfonate salt which is an anionic surfactant, and 1.0 to 5.0 parts by weight of a shrinkage reducing agent per 100 parts by weight of cement, and does not contain a thickener or an antifoaming agent. This allows the unit volume weight to be within 1 hour from immediately after the mortar is mixed. 3 As a result, it is possible to pump thick mortar for spraying over long distances. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-239384 A Summary of the Invention [Problem to be solved by the invention]

[0005] The thick spray mortar requires the use of special materials such as shrinkage reducing agents. In addition, since the cement-based spray material is sprayed onto a core material, it may be necessary for the cement-based spray material to be self-supporting after spraying. Furthermore, since the cement-based spray material is sprayed from a nozzle, it is required that it can be efficiently pumped with a hose or nozzle.

[0006] The present disclosure aims to provide a cement-based sprayed material and construction method that can improve self-supporting properties after spraying and can be pumped efficiently. [Means for solving the problem]

[0007] The cement-based spraying material according to the present disclosure is a cement-based spraying material to be sprayed onto an object, the cement-based spraying material comprising: cement; 80 parts by weight or more and 200 parts by weight or less of fine aggregate relative to 100 parts by weight of cement; 30 parts by weight or less of water relative to 100 parts by weight of cement; and air having a volume ratio of 40% or less to the total volume of the cement, fine aggregate, and water when mixed; the cement-based spraying material is sprayed to a certain thickness onto the outer periphery of a core material formed into a frame shape in a plan view, and the hardened cement-based spraying material becomes the outer shell of a concrete structure. The core material includes steel materials and air tubes, the steel materials include H-shaped steel and L-shaped steel, and the multiple steel materials are arranged to line up along a first direction and a second direction intersecting the first direction, and the air tubes are arranged between the web of the H-shaped steel and the inner surface of the L-shaped steel, and between the webs of a pair of H-shaped steels lined up along the first direction. .

[0008] This cement-based spraying material contains 80 parts by weight or more and 200 parts by weight or less of fine aggregate and 30 parts by weight or less of water per 100 parts by weight of cement. Thus, by containing 80 parts by weight or more of fine aggregate and 30 parts by weight or less of water, the fluidity of the cement-based spraying material can be appropriately maintained, and the shape can be maintained after spraying. Furthermore, by containing 200 parts by weight or less of fine aggregate, the cement-based spraying material can be prevented from becoming too hard, and the pumping of the cement-based spraying material can be efficiently performed. Furthermore, this cement-based spraying material contains air in a volume of 40% or less of the total volume at the time of mixing. By containing air in a volume ratio of 40% or less, the pumping property and fluidity of the cement-based spraying material can be maintained, and the cement-based spraying material can be prevented from becoming too soft, thereby improving the self-supporting property after spraying.

[0009] The above-mentioned cement-based spraying material may be mixed with a foaming agent that promotes the formation of air. In this case, the amount of air in the cement-based spraying material can be secured by mixing the foaming agent, so that the pumpability of the cement-based spraying material can be improved by generating air with the foaming agent while improving the self-supporting property.

[0010] The foaming agent may contain any one of an alkyl sulfate surfactant, an alkyl aryl sulfonic acid surfactant, and an alkyl ether compound complex. In this case, the addition of a small amount of foaming agent can increase the air content of the cement-based spraying material, and the air content can be easily adjusted.

[0011] The construction method according to the present disclosure is a construction method for constructing a concrete structure using the above-mentioned cement-based spraying material, and includes a step of constructing a covering portion of a concrete structure by spraying the cement-based spraying material onto a core material. In this construction method, the above-mentioned cement-based spraying material is sprayed onto a core material to construct a covering portion of a concrete structure. Thus, since a cement-based spraying material with high pumpability and self-supporting property is sprayed onto the core material, the cement-based spraying material can be efficiently sprayed to a certain thickness. Therefore, the spraying of the cement-based spraying material onto the core material and the construction of the concrete structure can be efficiently performed.

[0012] The above-mentioned construction method includes a step of preparing a cement-based spraying material by kneading cement, fine aggregate, and water before the step of constructing the covering portion, so that the volume of air is 40% or less relative to the total volume of the cement, fine aggregate, and water, and in the step of constructing the covering portion, the cement-based spraying material may be sprayed so that the volume of air is 7% or less relative to the volume of the sprayed cement-based spraying material. In this case, by preparing a cement-based spraying material mixed with air at a volume ratio of 40% or less, the cement-based spraying material can be efficiently pumped. In addition, by spraying the cement-based spraying material so that the volume ratio of air in the cement-based spraying material is 7% or less, the self-supporting property of the cement-based spraying material after spraying can be further improved. Effect of the Invention

[0013] According to the present disclosure, it is possible to improve the self-supporting property after spraying and to efficiently perform pressure feeding. [Brief description of the drawings]

[0014] [Figure 1] Fig. 1(a) is a perspective view showing an example of a steel material for a concrete structure, and Fig. 1(b) is a perspective view showing an example of a core material for a concrete structure. [Diagram 2]Fig. 2(a) is a perspective view showing a state where a cement-based spraying material is sprayed onto the core material of Fig. 1(b) to form an outer shell, and Fig. 2(b) is a perspective view showing a state where the core material is removed from the constructed outer shell. [Diagram 3] FIG. 3 is a perspective view showing an example of a completed concrete structure. [Figure 4] FIG. 4 is a perspective view that illustrates a typical example of a cement-based spraying material. [Diagram 5] Fig. 5(a) is a side view showing the state of spraying the cement-based spraying material according to the embodiment, and Fig. 5(b) is a side view showing the state of constructing a structure using a 3D printer according to a comparative example. [Figure 6] Fig. 6(a) is a cross-sectional view showing the process of constructing a covering by spraying a cement-based spraying material onto a core material. Fig. 6(b) is a cross-sectional view showing the process of reinforcing bar after removing the core material from the constructed covering. Fig. 6(c) is a cross-sectional view showing the process of pouring a filler into the constructed covering. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the cement-based spraying material and construction method according to the present disclosure will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In addition, the drawings may be partially simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0016] In the cement-based spraying material and construction method according to the present embodiment, a structure is constructed. One example of the structure is a concrete structure. In general, when constructing a concrete structure, after assembling reinforcing bars, a formwork is arranged so as to surround the reinforcing bars, concrete is poured inside the formwork, and after curing for a certain period of time, the formwork is removed to construct the structure. Thus, in the construction of a structure, a plurality of types of work, including the arrangement of formwork, are mixed, and the work is currently complicated. In addition, in recent years, there has been a shortage of construction skilled workers, and the number of carpenter workers, such as formwork carpenters, has decreased, and there is a concern that it will be difficult to secure carpenter workers in the future.

[0017] In the cement-based spraying material and construction method according to the present embodiment, for example, the outer shell structure of a structure is constructed by spraying the cement-based spraying material. Therefore, the arrangement of formwork is unnecessary, and the work can be performed efficiently. As a result, even in a situation where there is a shortage of workers such as carpenters, the construction work of the structure can be performed efficiently.

[0018] First, an example of the construction of a structure will be described. In this embodiment, a concrete structure is constructed. First, as shown in Fig. 1(a) and Fig. 1(b), a core material 1 is installed. The core material 1 corresponds to an example of an object to which a cement-based spraying material M (see Fig. 2) is sprayed. The core material 1 includes, for example, a steel material 2 and an air tube 3. As an example, the steel material 2 includes an H-steel 2b and an L-steel 2c. However, the type of steel material is not particularly limited. Moreover, the core material may include an expanded metal instead of the air tube 3, and the type of the core material is also not particularly limited.

[0019] First, a plurality of steel materials 2 are arranged so that their longitudinal direction is aligned with the vertical direction D1, and are aligned along the first direction D2 and the second direction D3. At this time, the plurality of steel materials 2 are arranged so that they form a frame in a plan view. The first direction D2 indicates the longitudinal direction of the plurality of steel materials 2 in a plan view, and the second direction D3 indicates the lateral direction of the plurality of steel materials 2 in a plan view.

[0020] In plan view, the multiple steel materials 2 may be arranged to form a rectangular frame. In this case, the four L-shaped steel pieces 2c form the corners of the steel material 2 in plan view, and the multiple H-shaped steel pieces 2b form the sides of the steel material 2 in plan view. For example, each H-shaped steel piece 2b is arranged so that a flange portion faces the outside of the steel material 2 in plan view, and each L-shaped steel piece 2c is arranged so that the outer surface of the L-shaped steel piece 2c faces the outside of the steel material 2 in plan view.

[0021] For example, two groups C1 each consisting of a plurality (three) of H-shaped steel bars 2b aligned along the first direction D2 are aligned along the second direction D3, and then an L-shaped steel bar 2c is placed at each end of each group C1. Then, the H-shaped steel bar 2b is placed between the pair of L-shaped steel bars 2c aligned along the second direction D3. The steel materials 2 are arranged as described above as an example, but the type, number and arrangement of the steel materials 2 are not limited to the above example and can be changed as appropriate.

[0022] After the steel material 2 is placed, the air tube 3 is placed. The air tube 3 has, for example, a columnar shape. A cross section of the air tube 3 cut in a direction perpendicular to the longitudinal direction is, for example, a rectangular shape with rounded corners. The air tube 3 is placed between a pair of steel materials 2. As a specific example, the air tube 3 is placed between the web of the H-shaped steel 2b and the inner surface of the L-shaped steel 2c, and between the webs of a pair of H-shaped steels 2b arranged along the first direction D2.

[0023] For example, the air tube 3 may include a first air tube 3b having a large cross-sectional area when cut along a plane perpendicular to the longitudinal direction, and a second air tube 3c having a small cross-sectional area when cut along a plane perpendicular to the longitudinal direction. As an example, the first air tube 3b is disposed so that the long side of the cross section extends along the first direction D2, and the second air tube 3c is disposed so that the long side of the cross section extends along the second direction D3.

[0024] For example, two sets C2 each consisting of a plurality of first air tubes 3b (four tubes as an example) aligned along the first direction D2 are arranged along the second direction D3, and then a plurality of second air tubes 3c (two tubes as an example) are arranged between each pair of sets C2. The above is an example of the arrangement of the air tubes 3, but the shape, size, number and arrangement of the air tubes 3 are not limited to the above example and can be changed as appropriate.

[0025] After the core material 1 (steel material 2 and air tube 3) is placed, as shown in Figures 2(a) and 2(b), a cement-based spraying material M with a constant thickness T is sprayed onto the outer periphery 1b of the core material 1 in a plan view to form the outer shell S1 of the structure S. The cement-based spraying material M according to this embodiment is a material that hardens over time.

[0026] In this embodiment, the hardened cementitious spraying material M becomes the outer shell S1, making it possible to eliminate the need for a formwork. In addition, since the outer shell S1 of the structure S can be formed by spraying the cementitious spraying material M, automating the spraying of the cementitious spraying material M makes it possible to mechanically construct the outer shell S1, which corresponds to the formwork of the structure S. Furthermore, since the outer shell S1 is formed from the cementitious spraying material M, it is possible to eliminate the need for demolding work, improving the durability of the structure of the outer shell S1. In addition, when the core material 1 contains H-shaped steel 2b, the H-shaped steel 2b improves the structural performance of the structure S.

[0027] The cement-based spraying material M is sprayed, for example, onto the outer peripheral surface 2d of the steel material 2 and the outer peripheral surface 3d of the air tube 3. The outer peripheral surface 2d of the steel material 2 includes, for example, the outer surface of the flange of the H-shaped steel 2b and the outer surface of the L-shaped steel 2c. The outer peripheral surface 3d of the air tube 3 is the outer surface of the air tube 3 exposed between a pair of steel materials 2 (the H-shaped steel 2b or the L-shaped steel 2c).

[0028] After the cement-based spraying material M is sprayed and hardened, the air tube 3 is taken out and removed. Then, as shown in Fig. 2(b) and Fig. 3, a reinforcing bar cage is placed in the hollow portion S2 inside the outer shell S1, and concrete S3 is poured, and then the construction of the structure S, which is a concrete structure, is completed.

[0029] As shown in FIG. 4, the cementitious spraying material M according to this embodiment is made of a thick material. When constructing an outer shell or the like by spraying the cementitious spraying material, it is necessary to attach the cementitious spraying material to the core material so as not to cause sagging. In order to prevent sagging, it is possible to add a quick-setting agent or a hardening accelerator to the cementitious spraying material. However, when a quick-setting agent or a hardening accelerator is added, the surface of the cementitious spraying material hardens immediately, which may make it difficult to finish with a trowel. Therefore, there is a problem that the surface finishing may not be performed appropriately.

[0030] Therefore, in this embodiment, by spraying a thick cementitious spraying material M, it is possible to adhere the cementitious spraying material M to a vertical surface without dripping. The adhesion of the cementitious spraying material M to a vertical surface can be prevented without dripping even without adding a quick-setting agent or a hardening accelerator. After spraying the cementitious spraying material M, the surface of the cementitious spraying material M can be finished with a trowel.

[0031] For example, the cement-based spraying material M contains cement, fine aggregate, water, and air. The cement-based spraying material M contains 80 parts by weight or more and 200 parts by weight or less of fine aggregate and 30 parts by weight or less of water with respect to 100 parts by weight of cement. In this case, the cement-based spraying material M can be used as a thick-mixed material.

[0032] The lower limit of the amount of fine aggregate in the cement-based spraying material M may be 90 parts by weight or more, 100 parts by weight or more, or 120 parts by weight or more relative to 100 parts by weight of cement. The upper limit of the amount of fine aggregate in the cement-based spraying material M may be 180 parts by weight or less, 160 parts by weight or less, or 150 parts by weight or less relative to 100 parts by weight of cement.

[0033] The upper limit of the amount of water in the cement-based spraying material M may be 25% or less, or 20% or less, based on 100 parts by weight of cement. The lower limit of the amount of water in the cement-based spraying material M may be 10% or more, 12% or more, 13% or more, 14% or more, or 15% or more, based on 100 parts by weight of cement.

[0034] The table flow test described in "12. Flow test 12.2 Characteristics of flow value" of JIS R 5201:2015 (Physical test method for cement) was performed on the cementitious spraying material M, and the result was 100+10mm at 0 hit flow. Because the container used in the test was 100mm in size, it was found that the shape of the cementitious spraying material M hardly changed.

[0035] In the above table flow test, the cementitious spraying material M is packed in two layers into a flow cone placed on a flow table, and the cementitious spraying material M is poked 15 times with a poker rod, and the surface of the cementitious spraying material M is smoothed, and then the flow cone is removed vertically. The cementitious spraying material M is then subjected to 15 dropping movements, and the maximum diameter after the cementitious spraying material M spreads and the diameter at a right angle thereto are measured, and the average value of these is the table flow value.

[0036] The cementitious spraying material M contains air, for example, at a volume ratio of 40% or less relative to the total volume of the cement, fine aggregate, and water when mixed. This reduces the viscosity of the thickened cementitious spraying material M, making it possible to pump the cementitious spraying material M. The upper limit of the volume ratio of air may be 35% or less or 30% or less. The lower limit of the volume ratio of air may be 10% or more, 15% or more, or 20% or more.

[0037] For example, when the cement-based spraying material M contains air whose volume ratio to the total volume at the time of mixing is 20% or more and 40% or less, the properties of the cement-based spraying material M become like whipped cream, the viscosity of the cement-based spraying material M decreases, and the pumpability of the cement-based spraying material M improves. In this way, even when the cement-based spraying material M containing air with a volume ratio of 40% or less is sprayed, the cement-based spraying material M foams after spraying and the air content of the cement-based spraying material M becomes 7% or less (it may be 6.5% or less, or 6% or less). Therefore, it is possible to make the air content of the cement-based spraying material M after spraying comparable to the air content of general concrete.

[0038] For example, a foaming agent is mixed into the cement-based spraying material M. By mixing the foaming agent into the cement-based spraying material M, the amount of air is increased when the cement-based spraying material M is mixed. The foaming agent mixed into the cement-based spraying material M may be any one of a synthetic surfactant, a resin soap-based foaming agent, and a protein-based foaming agent.

[0039] As a foaming agent of synthetic surfactant, for example, an alkyl sulfate surfactant used for lightweight embankment can be mentioned. In this case, it is possible to further increase the air content of the cement-based spraying material M by simply mixing a small amount of foaming agent.

[0040] However, the foaming agent mixed into the cement-based spraying material M is not limited to the alkyl sulfate surfactant. Examples of the foaming agent include fatty acid soap type, acylated sarcosine salt, disproportionated rosin acid soap, fatty oil sulfate ester salt, alkyl ether sulfate salt, amide ether sulfate, alkyl allyl sulfonate, alkyl ether sulfonate, naphthalene sulfonate, sulfosuccinic acid diester salt, sulfosuccinic acid ester salt, acylated methyl taurine salt, acylated taurine salt, alkyl phosphate ester, alkyl ether phosphate ester, quaternary ammonium salt, alkyl amidoamine, amphoteric surfactant, alkyl betaine type, sulfobetaine type, alkyl amido betaine type, and imidazoline type. , amine oxide, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyethylene glycol alkyl ester, polyoxyalkylene glycol rosinate ester, sorbitan fatty acid ester, glycerin fatty acid ester, glycerin fatty acid ester borate ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester borate ester, polyoxyethylene alkylamine, fatty acid monoethanolamide, fatty acid diethanolamide, keratin protein, casein, or albumin. In this case, the air content of the cement-based spraying material M can also be effectively increased.

[0041] Methods for mixing foaming agents into cement-based spraying materials include, for example, mixing liquid foaming agents as part of the water during mixing and mixing with a mixer to incorporate air. Another method is to whip the foaming agent in advance in a dedicated mixer and mix it with a separately mixed cement-based spraying material to incorporate air. Still another method is to add powdered foaming agent together with the cement and fine aggregate during mixing and mix with a mixer to incorporate air.

[0042] Incidentally, when constructing a structure A using a cement-based spraying material M such as the above-mentioned outer shell S1, a method using 3D printing may be considered, as shown in Fig. 5(b). With 3D printing, a trajectory can be freely drawn, so that a structure A can be easily formed even if it has a complex shape with curved surfaces, etc.

[0043] However, in 3D printing, because structure A is constructed by stacking layers of cement-based spraying material M, the adhesive strength in the interlayer portions is lower than in the non-interlayer portions. Therefore, there is concern that the interlayer portions may become structurally weak points of structure A, and furthermore, because the interlayer portions may become paths through which deterioration factors such as water or salt may penetrate, there is room for improvement in terms of the durability of structure A.

[0044] Therefore, in the construction method according to this embodiment, the structure A is constructed by spraying the cement-based spraying material M. When the structure A is constructed by spraying the cement-based spraying material M, the above-mentioned interlayer portion does not exist, so that the durability of the structure A can be improved. Below, an example of the construction method according to this embodiment will be described with reference to Figures 5(a), 6(a), 6(b), and 6(c).

[0045] First, a core material is constructed (process of constructing a core material). For example, a core material 11 formed in a frame shape in a plan view is constructed. The core material 11 may be, for example, the air tube 3 described above or may be expanded metal, and the type of the core material 11 can be changed as appropriate. For example, when the core material 11 is the air tube 3, it is removed after the concrete covering portion B1 described later is constructed, but when the core material 11 is expanded metal, it is buried and killed after the covering portion B1 is constructed.

[0046] Meanwhile, cement, fine aggregate, and water are mixed to prepare a cement-based spraying material M (a step of preparing a cement-based spraying material). At this time, cement, 80 parts by weight or more and 200 parts by weight or less of fine aggregate per 100 parts by weight of cement, and 30 parts by weight or less of water per 100 parts by weight of cement are mixed.

[0047] Then, the air content of the cement-based spraying material M is increased, for example, until the volume ratio to the total volume of the cement, fine aggregate, and water when mixed becomes 40%. At this time, for example, a foaming agent may be mixed into the cement-based spraying material M to increase the air content of the cement-based spraying material M (a step of mixing a foaming agent, a step of increasing the air content).

[0048] Next, the cement-based spraying material M is sprayed onto the outer surface 11b of the core material 11 from a material spraying device equipped with, for example, a hose H1 and a nozzle H2 (step of spraying the cement-based spraying material). As described above, the cement-based spraying material M is a thick material and can be sprayed thickly. For example, the cement-based spraying material M is sprayed onto the outer surface 11b of the core material 11 so that the thickness F is 10 cm or more.

[0049] The covering portion B1 of the structure B is constructed by continuously spraying the cementitious spraying material M (a process of constructing the covering portion). Then, the surface of the cementitious spraying material M is smoothed with a trowel (a process of finishing the cementitious spraying material with a trowel). After that, the cementitious spraying material M is hardened to complete the covering portion B1 of concrete (a process of hardening the cementitious spraying material).

[0050] At this time, the air contained in the cement-based spraying material M is diffused by spraying the cement-based spraying material M, and the volume ratio of the air in the cement-based spraying material M after spraying is set to 7% or less of the total volume ratio of the cement-based spraying material M (step of reducing the air volume). Then, when the core material 11 is an air tube 3, the core material 11 is removed, and a reinforcing bar cage G is placed as shown in Fig. 6(b) (step of placing reinforcing bars).

[0051] At this time, for example, a reinforcing bar cage G including a plurality of main reinforcements G1 extending in the vertical direction and a plurality of tie bars G2 arranged so as to surround the plurality of main reinforcements G1 is placed inside the covering portion B1. After that, as shown in Fig. 6(c), concrete J is poured inside the covering portion B1 and hardened, and then the structure B, which is a concrete structure, is completed.

[0052] Next, the effects obtained from the cement-based spraying material M and construction method according to this embodiment will be described in detail. The cement-based spraying material M contains 80 parts by weight or more and 200 parts by weight or less of fine aggregate and 30 parts by weight or less of water per 100 parts by weight of cement. Therefore, by containing 80 parts by weight or more of fine aggregate and 30 parts by weight or less of water, the fluidity of the cement-based spraying material M can be appropriately maintained.

[0053] Furthermore, by including 200 parts by weight or less of fine aggregate, the cement-based spraying material M can be prevented from becoming too hard, and therefore the cement-based spraying material M can be efficiently pumped. Furthermore, the cement-based spraying material M includes air in an amount of 40% or less of the total volume when mixed. By including air in an amount of 40% or less by volume, the pumpability and fluidity of the cement-based spraying material M can be maintained, and the cement-based spraying material M can be prevented from becoming too soft, thereby improving its self-supporting ability after being sprayed.

[0054] The cement-based spraying material M according to this embodiment is mixed with a foaming agent that promotes the formation of air. Therefore, the amount of air in the cement-based spraying material M can be secured by mixing the foaming agent, so that the amount of air in the cement-based spraying material M can be increased by the foaming agent while improving the self-supporting property, and the amount of air can be easily adjusted.

[0055] The foaming agent according to the present embodiment contains, for example, any one of an alkyl sulfate surfactant, an alkyl aryl sulfonic acid surfactant, and an alkyl ether compound complex. Therefore, the addition of a small amount of foaming agent can increase the air content of the cement-based spraying material M, and can easily adjust the air content.

[0056] In the construction method according to this embodiment, the covering portion B1 of the structure B is constructed by spraying the cement-based spraying material M. Therefore, the cement-based spraying material M, which has high pumpability and self-supporting property, is sprayed onto the core material 11, so that the cement-based spraying material M can be efficiently sprayed to a certain degree of thickness F. Therefore, the spraying of the cement-based spraying material M onto the core material 11 and the construction of the structure B can be efficiently performed.

[0057] The construction method according to the present embodiment includes a step of preparing a cement-based spraying material M by kneading cement, fine aggregate, and water so that the volume of air is 40% or less relative to the total volume of the cement, fine aggregate, and water, prior to the step of constructing the covering portion B1, and in the step of constructing the covering portion B1, the cement-based spraying material M is sprayed so that the volume of air is 7% or less relative to the volume of the sprayed cement-based spraying material M. Thus, by preparing the cement-based spraying material M containing air at a volume ratio of 40% or less, the cement-based spraying material M can be efficiently pumped. In addition, by spraying the cement-based spraying material M so that the volume ratio of air in the cement-based spraying material M is 7% or less, the self-supporting property of the cement-based spraying material M after spraying can be further improved.

[0058] In this embodiment, a construction method for forming the outer shell of a structure has been described, which includes a step of installing a core material 1, a step of spraying a cement-based spraying material M onto the outer peripheral portion 1b of the core material 1 in a plan view, and a step of hardening the sprayed cement-based spraying material M to construct the outer shell S1. This construction method makes it possible to eliminate the need for formwork, so that the construction work of the structure can be carried out efficiently. As a result, even in a situation where there is a shortage of workers such as carpenters, the construction work of the structure can be carried out efficiently.

[0059] The above describes the embodiments of the cement-based spraying material and the construction method according to the present disclosure. However, the present invention is not limited to the above-mentioned embodiments. In other words, it is easily recognized by those skilled in the art that various modifications and changes are possible within the scope of the present invention without changing the gist of the claims. For example, the composition of the cement-based spraying material and the contents and order of the steps of the construction method are not limited to the above-mentioned contents and can be appropriately modified.

[0060] For example, in the above-mentioned embodiment, an example was described in which the surface of the cement-based spraying material M was finished with a trowel after the covering portion B1 was constructed. However, it is not necessary to finish the surface of the cement-based spraying material with a trowel after the covering portion is constructed. In addition, in the above-mentioned embodiment, an example was described in which the outer shell S1 of the structure S was constructed by spraying the cement-based spraying material M. However, the cement-based spraying material and construction method according to the present invention can be applied to other than the construction of the outer shell structure. In addition, the cement-based spraying material and construction method according to the present invention can be applied to the construction of concrete structures as described above, and can also be applied to the construction of structures other than concrete structures. For example, the present invention can be applied to repair work of members by spraying materials, and can be applied to various sites. [Explanation of symbols]

[0061] 1,11...core material, 1b...periphery, 2...steel, 2b...H steel, 2c...L steel, 2d...periphery, 3...air tube, 3b...first air tube, 3c...second air tube, 3d...periphery, 11b...outer surface, A,B,S...structure, B1...cover, C1,C2...set, D1...vertical direction, D2...first direction, D3...second direction, G...reinforcing bar cage, G1...main bar, G2...hoop, H1...hose, H2...nozzle, J...concrete, M...cement-based sprayed material, S1...outer shell, S2...hollow portion, S3...concrete.

Claims

1. A method for constructing a concrete structure using a cement-based sprayed material sprayed onto an object, comprising the steps of: The cement-based spraying material is Cement and 80 parts by weight or more and 200 parts by weight or less of fine aggregate per 100 parts by weight of the cement; 30 parts by weight or less of water per 100 parts by weight of the cement; Air having a volume ratio of 40% or less to the total volume of the cement, the fine aggregate, and the water when mixed; having A certain thickness of the cement-based spraying material is sprayed onto the outer periphery of a core material formed into a frame shape in a plan view, and the hardened cement-based spraying material becomes the outer shell of the structure, The core material includes a steel material and an air tube, and the steel material includes an H-shaped steel and an L-shaped steel. A plurality of the steel materials are arranged so as to be aligned along a first direction and a second direction intersecting the first direction, The air tubes are disposed between the web of the H-shaped steel and the inner surface of the L-shaped steel, and between the webs of a pair of the H-shaped steels arranged along the first direction, A step of constructing a covering portion of the concrete structure by spraying the cement-based spraying material onto the core material, How to build it:

2. a step of preparing the cement-based spraying material by kneading the cement, the fine aggregate and the water so that the volume of air relative to the total volume of the cement, the fine aggregate and the water is 40% or less, prior to the step of constructing the covering portion; In the step of constructing the covering portion, the cement-based spraying material is sprayed so that the volume of air relative to the volume of the sprayed cement-based spraying material is 7% or less. The method of claim 1 .

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