Systems and methods for pouring sprayed concrete

Abstract

To provide a system and method for realizing a spraying method that offers high utilization efficiency of ready-mixed concrete and enables the sequestration of large amounts of carbon dioxide. [Solution] This system includes a transport pump, a carbon dioxide supply source, and a quick-setting agent additive device. The transport pump is configured to transport ready-mixed concrete to a nozzle via a delivery hose. The carbon dioxide supply source is configured to supply carbon dioxide-containing gas. The quick-setting agent additive device is configured to supply a quick-setting agent to the delivery hose or nozzle.

Description

Technical Field

[0001] One embodiment of the present invention relates to a system and method for placing sprayed concrete on tunnel inner walls, cliff faces, slope faces, etc.

Background Art

[0002] As a method for covering the inner walls of tunnels, cliff faces, and slope faces, the spraying method is used. The spraying method is a method in which compressed air is applied to ready-mix concrete to which a quick-setting agent has been added, and the ready-mix concrete is sprayed from the tip of a nozzle onto an excavation face, a cliff face, a slope face, etc., and rapidly cured. (See Patent Documents 1 to 8). By using the spraying method, it is possible to prevent the collapse of rock masses, natural ground, slope faces, etc. after tunnel excavation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Summary of the Invention

Problems to be Solved by the Invention

[0004] One embodiment of the present invention aims to provide a new system and method applicable to spraying methods. Alternatively, one embodiment of the present invention aims to provide a system and method for realizing a spraying method that has high utilization efficiency of ready-mixed concrete and is capable of fixing a large amount of carbon dioxide. [Means for solving the problem]

[0005] One embodiment of the present invention is a system for pouring sprayed concrete. This system includes a transport pump, a carbon dioxide supply source, and a quick-setting agent dispenser. The transport pump is configured to transport ready-mixed concrete to a nozzle via a delivery hose. The carbon dioxide supply source is configured to supply carbon dioxide-containing gas. The quick-setting agent dispenser is configured to supply a quick-setting agent to the delivery hose or nozzle.

[0006] One embodiment of the present invention is a method for placing sprayed concrete. This method includes supplying ready-mixed concrete to a nozzle via a delivery hose, adding a quick-setting agent to the ready-mixed concrete in the delivery hose or nozzle, and supplying compressed carbon dioxide-containing gas to the ready-mixed concrete in at least one of the delivery hose and the nozzle. [Brief explanation of the drawing]

[0007] [Figure 1] A block diagram of a system for pouring sprayed concrete, which is one embodiment of the present invention. [Figure 2A] A schematic diagram illustrating the process of pouring sprayed concrete into a tunnel using a sprayed concrete pouring method, which is one embodiment of the present invention. [Figure 2B] A schematic diagram illustrating the process of pouring sprayed concrete into a tunnel using a sprayed concrete pouring method, which is one embodiment of the present invention. [Figure 3A]A schematic diagram illustrating the process of pouring sprayed concrete into a tunnel using a sprayed concrete pouring method, which is one embodiment of the present invention. [Figure 3B] A schematic diagram illustrating the process of pouring sprayed concrete into a tunnel using a sprayed concrete pouring method, which is one embodiment of the present invention. [Modes for carrying out the invention]

[0008] The embodiments of the present invention will be described below with reference to the drawings and other materials. However, the present invention can be implemented in various forms without departing from its spirit, and is not to be interpreted as being limited to the embodiments described below.

[0009] While drawings may schematically represent the width, thickness, shape, etc., of each part compared to the actual embodiment in order to clarify the explanation, these are merely examples and do not limit the interpretation of the present invention. In this specification and each figure, elements having the same function as those described in previously shown figures are denoted by the same reference numeral, and redundant explanations may be omitted. This reference numeral is used to represent multiple identical or similar structures collectively, and when representing them individually, a hyphen and a natural number are added after the reference numeral.

[0010] In this specification, concrete refers to a hardened material that does not exhibit fluidity, formed when cement, one of the raw materials, reacts with water to produce hydrates. Concrete may contain fine aggregate with a diameter of 5 mm or less and coarse aggregate with a diameter greater than 5 mm (for example, greater than 5 mm and 20 mm or less, or 10 mm or more and 20 mm or less). On the other hand, concrete before hardening, that is, concrete in a state in which the mixture containing cement and water has not completely hardened and retains fluidity, is called ready-mixed concrete (also called fresh concrete). In addition to cement, water, and aggregate, ready-mixed concrete may contain additives such as air-entraining agents (aerosols), fluidizers, and thickeners.

[0011] 1. System for pouring sprayed concrete Figure 1 shows a block diagram of the configuration of a system 100 for pouring sprayed concrete (hereinafter simply referred to as the pouring system) according to one embodiment of the present invention. As shown in Figure 1, the pouring system 100 comprises a tank 102 for storing ready-mixed concrete, a transport pump 104 for pumping the ready-mixed concrete, a pressure-resistant delivery hose 106 connected to the tank 102 via the transport pump 104, a nozzle 108 connected to the end of the delivery hose 106, and a carbon dioxide supply source 130 for supplying carbon dioxide-containing gas. The pouring system 100 may further include one or more compressors 132 for compressing the carbon dioxide-containing gas and supplying it to the delivery hose 106 or the nozzle 108. The pouring system 100 further includes a quick-setting agent adder 120 for adding a quick-setting agent.

[0012] In the concrete placement system 100, ready-mixed concrete stored in tank 102 is sprayed onto the tunnel excavation face, cliff face, slope face, etc., via nozzle 108. The ready-mixed concrete may be supplied directly to tank 102 from a ready-mixed concrete manufacturing plant near the site where the sprayed concrete is placed, or it may be transported from any ready-mixed concrete manufacturing plant by an agitator truck and supplied to tank 102.

[0013] The transport pump 104 is a device for pressurizing the ready-mixed concrete in the tank 102 to the delivery hose 106. Any type of pump can be used as the transport pump 104, such as a piston pump, a swing valve pump, or a cylinder swing pump. In Figure 1, the tank 102 and the transport pump 104 are shown in different configurations. However, a concrete pump having the functions of these configurations may also be used. Although not shown, the concrete pump is composed of a hopper for charging ready-mixed concrete, one or more pumps for pumping ready-mixed concrete, a pumping cylinder for injecting ready-mixed concrete into the delivery hose 106, and the like.

[0014] In order to spray the ready-mixed concrete more efficiently, a compressor 110 for supplying compressed air may be provided. The compressor 110 may be a reciprocating type or a rotary type. The compressor 110 may be connected to the delivery hose 106 as shown in FIG. 1, but the compressor 110 may be further connected to the nozzle 108 to configure the placing system 100 such that compressed air and ready-mixed concrete are mixed within the nozzle 108.

[0015] The delivery hose 106 is connected to the tank 102 via a transport pump 104 (or a concrete pump; the same applies hereinafter), and transports the ready-mixed concrete pumped from the transport pump 104 to the nozzle 108. The delivery hose 106 is a hose having both flexibility and pressure resistance. For example, the inner diameter is about 30 mm to 65 mm, and the outer diameter is about 45 mm to 90 mm. Examples of the hose include a hose containing synthetic fibers such as aromatic polyamide and polyimide. The nozzle 108 is a metal tube-shaped member provided at the tip of the delivery hose 106, and a spray gun type or a ring gun type can be adopted according to the supply amount of the ready-mixed concrete, the spray area, and the like.

[0016] The carbon dioxide supply source 130 is configured to supply a carbon dioxide-containing gas containing carbon dioxide at a concentration higher than that of the atmosphere, specifically, at a concentration higher than 400 ppm and 100% or less. The carbon dioxide-containing gas may contain major components of the atmosphere such as nitrogen and oxygen, or may contain noble gases such as argon. Further, the carbon dioxide-containing gas may contain water (water vapor). The carbon dioxide supply source 130 may be a cylinder filled with carbon dioxide. When a cylinder is used, a carbon dioxide-containing gas whose pressure is adjusted by a regulator attached to the cylinder is used. When a facility (such as a chemical plant, a waste incineration facility, a thermal power plant, or various other factories) that emits a large amount of carbon dioxide is already installed near the site where the sprayed concrete is placed, these facilities may be used as the carbon dioxide supply source 130. In the latter case, the exhaust gas of the facility, or a purified gas obtained by performing dust removal, desulfurization, denitration, etc. on the exhaust gas may be used as the carbon dioxide-containing gas. Thus, by using the exhaust gas from the facility, the cost for transporting the carbon dioxide-containing gas is reduced, and the emission of carbon dioxide associated with transportation is prevented.

[0017] One or more compressors 132 are configured to compress carbon dioxide-containing gas supplied from a carbon dioxide supply source 130 and supply it to at least one of the delivery hose 106 and the nozzle 108. The compressors 132 may be reciprocating or rotary. By providing the carbon dioxide supply source 130 and the compressors 132, high-pressure carbon dioxide-containing gas is mixed with the ready-mixed concrete in the delivery hose 106 and / or the nozzle 108. As a result, pressure is obtained for spraying the ready-mixed concrete from the nozzle 108, and a reaction between carbon dioxide and the ready-mixed concrete can be triggered, for example, the reaction between calcium hydroxide in the ready-mixed concrete and carbon dioxide to produce calcium carbonate. As a result, ready-mixed concrete can be efficiently sprayed onto excavation surfaces, cliff faces, slopes, etc., as will be described later. Note that if a cylinder is used as the carbon dioxide supply source 130, the compressor 132 may be omitted, and the carbon dioxide-containing gas regulated by a regulator may be supplied directly to the delivery hose 106 or the nozzle 108.

[0018] As an optional configuration, as shown in Figure 1, a temperature controller 134 for controlling the temperature of the carbon dioxide-containing gas mixed with the ready-mixed concrete, and a humidifier 136 for controlling the humidity may be installed between the carbon dioxide supply source 130 and the delivery hose 106 or nozzle 108, between the carbon dioxide supply source 130 and the compressor 132, between the compressor 132 and the delivery hose 106, and / or between the compressor 132 and the nozzle 108. In this case, a concentration meter 138, a thermometer 140, and a hygrometer 142 for measuring the carbon dioxide concentration, temperature, and humidity of the carbon dioxide-containing gas may be appropriately installed in the concrete pouring system 100. The concentration meter 138, thermometer 140, and hygrometer 142 may also have communication functions. Specifically, each may be equipped with a battery and configured to measure the carbon dioxide concentration, temperature, and humidity as needed or periodically, and transmit this information wirelessly or via wired connection to the carbon dioxide supply source 130, temperature controller 134, humidifier 136, etc. By mixing a carbon dioxide-containing gas with controlled carbon dioxide concentration, temperature, and humidity with ready-mixed concrete, it becomes possible to control the reaction rate between carbon dioxide and ready-mixed concrete. As described later, this allows for more precise control of the viscosity of the ready-mixed concrete sprayed from nozzle 108, suppression of rebound phenomena, and efficient carbon dioxide fixation.

[0019] The quick-setting agent additive device 120 is connected to the delivery hose 106 or nozzle 108 and is configured to supply the quick-setting agent to the delivery hose 106 or nozzle 108. As the quick-setting agent, solid quick-setting agents such as alkali metal carbonates or silicates, sodium aluminate, and calcium aluminate, as well as solutions or suspensions containing water, can be used. When the quick-setting agent supplied from the quick-setting agent additive device 120 is mixed with the ready-mixed concrete, the hydration reaction of the ready-mixed concrete is promoted, the viscosity of the ready-mixed concrete is increased, and the sprayed ready-mixed concrete can be solidified in a short time. As a result, the rebound phenomenon can be effectively suppressed.

[0020] As an optional configuration, the concrete casting system 100 may further include a compressor 122 connected to the quick-setting agent addition device 120. By providing the compressor 122, the quick-setting agent can be supplied to the delivery hose 106 or nozzle 108 at a higher speed. Alternatively, instead of, or in conjunction with, the compressor 122, a compressor 132 for compressing carbon dioxide-containing gas may be connected between the quick-setting agent addition device 120 and the delivery hose 106 or between the quick-setting agent addition device 120 and the nozzle 108 (see Figure 1). Or, if a cylinder is used as the carbon dioxide supply source 130, the concrete casting system 100 may be configured to supply carbon dioxide-containing gas, which has been regulated by a regulator, to the quick-setting agent addition device 120.

[0021] 2. Method for placing sprayed concrete using a concrete placement system The following describes a method for spraying ready-mixed concrete using the placement system 100. Here, as an example, we will describe a method in which ready-mixed concrete is sprayed onto the inner wall of a tunnel formed by excavating bedrock using the spraying method, and then lining concrete is formed. Note that sprayed concrete is sometimes called primary lining concrete, and in this case, the lining concrete placed on its surface is also called secondary lining concrete.

[0022] First, ready-mixed concrete is prepared. Ready-mixed concrete is prepared by adding water to a mixture of cement and aggregate and mixing it. At this time, additives such as air-entraining agents (aerosols), fluidizers, and thickeners may be added as appropriate. The prepared ready-mixed concrete is filled into tank 102.

[0023] Next, the ready-mixed concrete filled in tank 102 is transported to transport pump 10 The mixture is pumped into the delivery hose 106 using 4. Furthermore, carbon dioxide-containing gas supplied from the carbon dioxide supply source 130 is supplied to the delivery hose 106 and / or nozzle 108. The pressure of the carbon dioxide-containing gas may be adjusted using a regulator (not shown) or a compressor 132. Simultaneously, a quick-setting agent is supplied from the quick-setting agent additive device 120 to the delivery hose 106 and / or nozzle 108, and the quick-setting agent and ready-mixed concrete are mixed in the delivery hose 106 or nozzle 108. The quick-setting agent may be supplied using a transport pump (not shown) or by supplying compressed air from the compressor 122 to the quick-setting agent additive device 120. In addition, data from the concentration meter 138, thermometer 140, and hygrometer 142 may be acquired as needed, and the flow rate of the carbon dioxide-containing gas, the temperature and humidity of the carbon dioxide-containing gas may be adjusted as appropriate using the compressor 132, temperature controller 134, and humidifier 136.

[0024] Subsequently, ready-mixed concrete is sprayed from nozzle 108 onto the tunnel inner wall 150 shown in Figure 2A. The sprayed ready-mixed concrete is fluid, but hardens rapidly due to the presence of a quick-setting agent. Furthermore, carbon dioxide-containing gas is supplied to the ready-mixed concrete, causing the calcium hydroxide in the ready-mixed concrete to react with carbon dioxide, resulting in the precipitation of calcium carbonate, which has extremely low solubility in water, as a solid. This reaction further increases the viscosity of the ready-mixed concrete. As a result, the sprayed ready-mixed concrete hardens rapidly, forming sprayed concrete 152 on the tunnel inner wall 150. The reaction rate between ready-mixed concrete and carbon dioxide is affected by the carbon dioxide concentration in the carbon dioxide-containing gas, temperature, and humidity. Therefore, the hardening rate of the ready-mixed concrete can be controlled by appropriately controlling and adjusting the carbon dioxide concentration in the carbon dioxide-containing gas, temperature, and humidity.

[0025] Next, lining concrete is poured onto the surface of the sprayed concrete 152. Specifically, as shown in Figure 2B, an arch-shaped formwork 154 is formed after the sprayed concrete 152 is poured, and ready-mixed concrete is poured between the formwork 154 and the sprayed concrete 152 and allowed to harden. This forms the lining concrete 156 that covers the sprayed concrete 152 (Figure 3A). After this, the formwork 154 is removed, completing the pouring of the concrete wall onto the tunnel inner wall 150.

[0026] In conventional spraying methods, sprayed ready-mixed concrete may bounce off excavation surfaces, cliff faces, or slopes, or it may adhere but then flow off without settling. These phenomena are called rebound phenomena. When rebound phenomena occur, it becomes difficult to efficiently set and harden the ready-mixed concrete. In contrast, in the spraying concrete placement method according to one embodiment of the present invention, not only the rapid-setting agent but also the precipitation of calcium carbonate due to reaction with carbon dioxide contributes to increasing the viscosity and hardening speed of the ready-mixed concrete. Therefore, the rebound phenomenon can be effectively suppressed, and ready-mixed concrete can be used efficiently.

[0027] Furthermore, the placement method using the placement system 100 allows for the placement of sprayed concrete 152 containing a high concentration of calcium carbonate, which is produced by the reaction between calcium hydroxide generated during cement hydration and carbon dioxide. Therefore, compared to sprayed concrete placed without using carbon dioxide-containing gas, sprayed concrete 152 containing a high concentration of calcium carbonate has a higher density and greater compressive strength. In fact, the inventors found that approximately 20% (60 kg / m³) of the cement is present. 3 It has been confirmed that fixing carbon dioxide in concrete increases the compressive strength of the concrete by approximately 8% to 10%. Therefore, by applying the casting method according to one embodiment of the present invention, it is possible to form sprayed concrete 152 with higher strength than conventional sprayed concrete.

[0028] Furthermore, cement, a raw material for concrete, releases a large amount of carbon dioxide during its manufacture. However, by applying this placement method, the sprayed concrete 152 can have a high concentration of calcium carbonate, thus fixing a large amount of carbon dioxide. Although it depends on the type of cement and the composition of the ready-mixed concrete, the inventors' calculations suggest that up to 120 kg of carbon dioxide can be fixed per cubic meter of sprayed concrete 152. Therefore, the sprayed concrete placement system 100 and placement method according to the embodiment of the present invention can be used to fix a large amount of carbon dioxide, and can be said to contribute to the reduction of carbon dioxide and the mitigation of global warming.

[0029] The embodiments described above as examples of the present invention can be combined and implemented as appropriate, insofar as they do not contradict each other. Additions, deletions, or design modifications of components based on these embodiments, made by those skilled in the art, are also included within the scope of the present invention, as long as they retain the essence of the invention.

[0030] Any effects or benefits other than those brought about by the embodiments described above, if they are clear from the description herein or easily predictable to those skilled in the art, are naturally understood to be brought about by the present invention. [Explanation of Symbols]

[0031] 100: Placement system, 102: Tank, 104: Transport pump, 106: Delivery hose, 108: Nozzle, 110: Compressor, 120: Quick-setting agent addition device, 122: Compressor, 130: Carbon dioxide supply source, 132: Compressor, 134: Temperature controller, 136: Humidifier, 138: Concentration meter, 140: Thermometer, 142: Hygrometer, 150: Tunnel inner wall, 152: Sprayed concrete, 154: Formwork, 156: Lining concrete

Claims

1. A transport pump for delivering ready-mixed concrete to a nozzle via a delivery hose. A carbon dioxide source that supplies carbon dioxide-containing gas, and A system for pouring sprayed concrete, including a fastening agent additive device for supplying a fastening agent to the delivery hose or the nozzle.

2. The system according to claim 1, further comprising a first compressor connected to the carbon dioxide source, which compresses the carbon dioxide-containing gas and supplies it to at least one of the delivery hose and the nozzle.

3. The system according to claim 1, wherein the carbon dioxide concentration in the carbon dioxide-containing gas is higher than 400 ppm and 100% or less.

4. The system according to claim 1, further comprising a second compressor for supplying compressed air to the delivery hose.

5. The system according to claim 1, further comprising a temperature controller for adjusting the temperature of the carbon dioxide-containing gas.

6. The system according to claim 1, further comprising a humidifier for adjusting the humidity of the carbon dioxide-containing gas.

7. To supply ready-mixed concrete to a nozzle via a delivery hose, Adding a quick-setting agent to the ready-mixed concrete in the delivery hose or nozzle, and A method for placing sprayed concrete, comprising supplying compressed carbon dioxide-containing gas to the ready-mixed concrete in at least one of the delivery hose and the nozzle.

8. The concrete casting method according to claim 7, wherein the carbon dioxide concentration in the carbon dioxide-containing gas is higher than 400 ppm and 100% or less.

9. The concrete casting method according to claim 7, further comprising supplying compressed air to the ready-mixed concrete in the delivery hose.

10. The concrete casting method according to claim 7, further comprising controlling the temperature of the carbon dioxide-containing gas using a temperature controller.

11. The concrete casting method according to claim 7, further comprising controlling the humidity of the carbon dioxide-containing gas using a humidifier.

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