Precast concrete product manufacturing method and precast concrete product manufacturing device

Abstract

To provide a method for producing a precast concrete product in which the exhaust of carbon dioxide from a production site of a precast concrete product is suppressed, a production device for a precast concrete product, and a precast concrete product produced using the method.SOLUTION: A method for producing a precast concrete product comprises: a curing step in which a flask of a precast concrete product installed with concrete is arranged at the inside of a curing tank, and the concrete is heated while feeding water vapor into the curing tank; and an exhaust gas feeding step in which a carbon dioxide-containing exhaust gas is fed to the concrete or the raw material of the concrete.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a precast concrete product, an apparatus for manufacturing a precast concrete product, and a precast concrete product manufactured using the method. [Background technology]

[0002] Technological developments have been made for reducing emissions of carbon dioxide, a greenhouse gas. For example, in the field of civil engineering and construction, a technology has been developed for absorbing carbon dioxide into concrete structures, as disclosed in Patent Document 1, and a technology for producing carbonated concrete by reacting carbon dioxide with gamma belite, as disclosed in Patent Document 2. The former involves absorbing carbon dioxide from the air into a concrete structure, while the latter involves reacting carbon dioxide contained in the exhaust gas from a thermal power plant with gamma belite. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4829017 [Patent Document 2] Patent No. 4822373 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the need to reduce carbon dioxide emissions has become increasingly important, partly due to the widespread adoption of the Sustainable Development Goals (SDGs) adopted by the United Nations. In particular, in the civil engineering and construction sector, where large amounts of carbon dioxide are emitted during the manufacturing process of clinker, the raw material for cement, there is great significance in developing technologies to reduce carbon dioxide emissions. In view of the above circumstances, an object of the present invention is to provide a method for manufacturing a precast concrete product, which suppresses carbon dioxide emissions from a manufacturing site of the precast concrete product; and, Precast concrete product manufacturing equipment Place The purpose is to provide. [Means for solving the problem]

[0005] (1) A method for manufacturing a precast concrete product according to at least one embodiment of the present invention includes: Formwork in which concrete has been poured vapor Place in a curing tank vapor The concrete is heated while supplying steam into the curing tank. vapor The curing process, an autoclave curing step in which the concrete removed from the formwork after the steam curing step is placed in an autoclave and the concrete is heated while supplying steam into the autoclave; an exhaust gas supplying step of supplying exhaust gas containing carbon dioxide to the concrete or raw materials of the concrete; Equipped with 、 In the exhaust gas supplying step, the exhaust gas is supplied into the steam curing tank so as to supply the exhaust gas containing carbon dioxide to the concrete in the formwork placed in the steam curing tank during the steam curing step. do.

[0006] According to the above configuration (1), the exhaust gas is Inside the formwork placed in the steam curing tank Concrete To By supplying carbon dioxide in the exhaust gas, To Therefore, carbon dioxide is absorbed into the precast concrete product, and carbon dioxide in the exhaust gas can be prevented from being released into the atmosphere.

[0007] (2) In some embodiments, in the above configuration (1), Mix cement, aggregate and water Cast into the formwork A mixing step for preparing the concrete is provided, In the exhaust gas supplying step, before the mixing step , mixed with the cement and the aggregate In the water The exhaust gas Dissolve.

[0008] According to the above configuration (2), by supplying the exhaust gas to water, the carbon dioxide in the exhaust gas dissolves in the water, reacts with the water, and is absorbed. Here, the carbon dioxide that has dissolved in the water and reacted with the water also reacts with the cement when the water and cement are mixed, and is absorbed into the concrete. Therefore, the carbon dioxide in the exhaust gas mixed with water dissolves in the concrete, reacts with the concrete, and is absorbed, just as when the exhaust gas is mixed with the concrete. As a result, it is possible to suppress the release of carbon dioxide in the exhaust gas into the atmosphere.

[0009] (3) At least one embodiment of the precast concrete product manufacturing device of the present invention is A mold in which concrete has been poured can be housed and the mold can be heated by steam. vapor A curing tank; an autoclave capable of accommodating the concrete that has been heated in the steam curing tank and then removed from the formwork, and heating the concrete with steam; an exhaust gas supply means for supplying exhaust gas containing carbon dioxide to the concrete or raw materials of the concrete; Equipped with The exhaust gas supply means is capable of supplying the exhaust gas containing carbon dioxide into the steam curing tank in order to supply the exhaust gas to the concrete in the formwork placed in the steam curing tank. the law of nature, The exhaust gas supply means is further configured to dissolve the exhaust gas in water that is mixed with cement and aggregate to prepare the concrete that is poured into the formwork. .

[0010] According to the above configuration (3), the exhaust gas is Inside the formwork placed in the steam curing tank Concrete To By supplying carbon dioxide in the exhaust gas, To Therefore, carbon dioxide is absorbed into the precast concrete product, and carbon dioxide in the exhaust gas can be prevented from being released into the atmosphere.

[0012] The above configuration ( 3According to the study, by supplying exhaust gas to water, the carbon dioxide in the exhaust gas dissolves in the water, reacts with the water, and is absorbed. When the water and cement are mixed, the carbon dioxide that has dissolved in the water also reacts with the cement and is absorbed into the concrete. Therefore, the carbon dioxide in the exhaust gas mixed with water dissolves in the concrete, reacts with the concrete, and is absorbed, just as when it is mixed with concrete. As a result, it is possible to prevent the carbon dioxide in the exhaust gas from being released into the atmosphere. [Effects of the Invention]

[0015] According to the present invention, there is provided a method for producing a precast concrete product, which suppresses carbon dioxide emissions from a production site of the precast concrete product. and, Precast concrete product manufacturing equipment Place Provided. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a flowchart illustrating a general procedure of a method for manufacturing a precast concrete product according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram for explaining a mixing step. [Figure 3] FIG. 1 is a schematic diagram for explaining a concrete pouring process. [Figure 4] FIG. 1 is a schematic diagram for explaining a steam curing process. [Figure 5] FIG. 1 is a schematic diagram for explaining an autoclave curing step. [Figure 6] FIG. 2 is a schematic diagram for explaining an example of an exhaust gas supply means. [Figure 7] FIG. 2 is a schematic diagram for explaining an example of an exhaust gas supply means. [Figure 8] FIG. 2 is a schematic diagram for explaining an example of an exhaust gas supply means. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, several embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0018] Figure 1 is a flowchart illustrating the general steps of a method for manufacturing a precast concrete product (hereinafter simply referred to as the manufacturing method) according to one embodiment of the present invention. As shown in Figure 1, the manufacturing method includes a weighing step S1, a mixing step S3, a reinforcing bar assembling step S5, a formwork arranging step S7, a concrete pouring step S9, a steam curing step S11, a form stripping step S12, an autoclave curing step S13, and an exhaust gas supplying step S15. In the weighing step S1, the raw materials for concrete, that is, water, cement, and aggregate, are weighed. Note that the raw materials may also contain admixtures. In the mixing step S3, the raw materials for the concrete are mixed using a mixer 1 as shown in FIG. 2 to prepare concrete (ready-mixed concrete).

[0019] In the reinforcing bar assembly process S5, the reinforcing bars are assembled into a reinforcing bar assembly of a predetermined shape. Note that the raw materials for the reinforcing bar assembly may include deformed reinforcing bars, etc. In the formwork placement step S7, the reinforcing bar assembly is placed in the formwork.

[0020] In the concrete pouring step S9, the concrete prepared in the mixing step S3 is poured into the formwork 3 in which the reinforcing bar assemblies are arranged, as shown in Fig. 3. The precast concrete product of this embodiment is a box culvert. In the steam curing step S11, as shown in FIG. 4, the formwork 3 in which the concrete has been poured is placed in a curing tank. (Steam curing tank) The curing tank 5 is then placed in the formwork 3. Steam generated by a boiler 7 is supplied to the curing tank 5 to harden the concrete in the formwork 3 to a predetermined strength. The boiler 7 generates steam using heat generated by burning fuel, but the fuel is not particularly limited, and light oil, heavy oil, coal, etc. can be used. In the demolding process S12, after the steam curing process S11, it is confirmed whether the concrete has the required strength, and the intermediate precast concrete product is demolded from the formwork 3. The intermediate precast concrete product is composed of the rebar assembly and concrete that have undergone the steam curing process S11, and is the contents of the formwork 3 that have undergone the steam curing process S11.

[0021] In the autoclave curing step S13, as shown in Figure 5, an intermediate precast concrete product 11 is placed in an autoclave (pressure-resistant vessel) 9. The intermediate precast concrete product 11 is made up of a rebar assembly and concrete that have undergone the steam curing step S11, and is the contents of the formwork 3 that has undergone the steam curing step S11. Steam is then supplied from a boiler 7 into the autoclave 9, and the intermediate precast concrete product 11 is cured at a higher temperature and pressure than in the steam curing step S11. This hardens the concrete in the intermediate precast concrete product 11 to a predetermined strength, and a precast concrete product is obtained as the final product.

[0022] In the exhaust gas supply process S15, exhaust gas from the boiler 7 is supplied to the concrete or concrete raw materials that will make up the precast concrete product as shown in Figures 2 to 5 during the above-mentioned weighing process S1, mixing process S3, concrete pouring process S9, steam curing process S11, and autoclave curing process S13.

[0023] According to the above configuration, by supplying the exhaust gas discharged from the boiler 7 to concrete or concrete raw materials, the carbon dioxide in the exhaust gas dissolves in, reacts with, and is absorbed by the concrete or concrete raw materials. Therefore, the carbon dioxide is absorbed into the precast concrete product, and it is possible to prevent the carbon dioxide in the exhaust gas from being released into the atmosphere.

[0024] In some embodiments, in the exhaust gas supplying step S15, before the mixing step S3, the exhaust gas from the boiler 7 is dissolved in water, which is a raw material of concrete. According to the above configuration, by supplying the exhaust gas discharged from the boiler 7 to water, the carbon dioxide in the exhaust gas dissolves in the water, reacts with the water, and is absorbed. Here, when the water and cement are mixed, the carbon dioxide that has dissolved in the water also reacts with the cement and is absorbed into the concrete. Therefore, the carbon dioxide in the exhaust gas mixed with water dissolves in the concrete, reacts with the concrete, and is absorbed, just as when the exhaust gas is mixed with concrete. As a result, it is possible to suppress the release of carbon dioxide in the exhaust gas into the atmosphere.

[0025] The absorption of carbon dioxide by concrete and its raw materials can be thought of as being represented by the following general reaction formula: Note, however, that xCaO·ySiO2 in the formula represents calcium silicate, such as tricalcium silicate or dicalcium silicate (belite, γC2S), and the consistency of the number of moles on the left and right sides of the formula is ignored. As shown in the formula, calcium silicate, water, and carbon dioxide react to produce calcium carbonate. xCaO・ySiO2+H2O→vCaO・wSiO2・H2O+Ca(OH)2 Ca(OH)2+CO2→CaCO3+H2O The absorption of carbon dioxide by water is expressed by the following general reaction formula: As shown in the formula, carbon dioxide reacts with water to produce carbonic acid. CO2+H2O→H2CO3

[0026] Hereinafter, a manufacturing apparatus for precast concrete products (hereinafter also simply referred to as a manufacturing apparatus) according to one embodiment of the present invention will be described. The manufacturing apparatus includes a curing tank 5 and an exhaust gas supply means. As shown in Fig. 4, the curing tank 5 is configured to accommodate a form 3 for a precast concrete product in which concrete has been poured, and to be able to heat the form 3 for the precast concrete product with steam from a boiler 7. The exhaust gas supply means is configured to supply the exhaust gas from the boiler 7 to the concrete or raw materials for the concrete that will constitute the precast concrete product.

[0027] According to the above configuration, by supplying the exhaust gas discharged from the boiler 7 to concrete or concrete raw materials, the carbon dioxide in the exhaust gas dissolves in, reacts with, and is absorbed by the concrete or concrete raw materials. Therefore, the carbon dioxide is absorbed into the precast concrete product, and it is possible to prevent the carbon dioxide in the exhaust gas from being released into the atmosphere. In this embodiment, the case where the exhaust gas discharged from the boiler 9 is used has been described, but the present invention is not limited to the boiler 9 and may be any device that discharges exhaust gas containing carbon dioxide.

[0028] In some embodiments, as shown in FIG. 2, the exhaust gas supply means comprises a pump 13 capable of supplying the exhaust gas of the boiler 7 to a mixer 1 for preparing the concrete. In some embodiments, as shown in FIG. 3, the exhaust gas supply means includes a pump 17 that supplies the exhaust gas from the boiler 7 to a supply pipe 15 for the concrete being poured into the formwork 3.

[0029] In some embodiments, as shown in FIG. 4, the exhaust gas supply means includes a pump 19 that supplies exhaust gas from the boiler 7 into the curing tank 5. According to the above configuration, by supplying exhaust gas into the curing tank 5, the heat of the steam, the heat of the exhaust gas, and the reaction between the concrete and carbon dioxide allow the concrete to be cured at a high temperature, and the concrete can quickly attain the desired strength. Furthermore, since the greater the moisture content, the greater the amount of carbon dioxide absorbed, if exhaust gas is supplied to the curing tank 5 together with steam, a greater amount of carbon dioxide can be absorbed by the precast concrete product.

[0030] In some embodiments, as shown in FIG. 5, the exhaust gas supply means includes a pump 21 that supplies the exhaust gas of the boiler 7 into the autoclave 9. According to the above configuration, by supplying exhaust gas into the autoclave 9, the heat and pressure of the steam, as well as the heat and pressure of the exhaust gas and the reaction between the concrete and carbon dioxide, allow the concrete to be cured at high temperature and pressure, and the desired strength can be achieved quickly. Furthermore, since the greater the moisture content, the greater the amount of carbon dioxide absorbed, if exhaust gas is supplied to the autoclave 9 together with steam, more carbon dioxide can be absorbed into the precast concrete product.

[0031] In some embodiments, the flue gas supply means is configured to dissolve the flue gas of the boiler 7 in water for mixing with cement and aggregate to prepare concrete. According to the above configuration, by supplying the exhaust gas discharged from the boiler 7 to water, the carbon dioxide is mixed with the water, and the carbon dioxide in the exhaust gas dissolves in the water, reacts with the water, and is absorbed. Here, the carbon dioxide that has dissolved in the water and reacted with the water also reacts with the cement when the water and cement are mixed, and is absorbed into the concrete. Therefore, the carbon dioxide in the exhaust gas mixed with water dissolves in the concrete, reacts with the concrete, and is absorbed, just as when the exhaust gas is mixed with the concrete. As a result, it is possible to suppress the release of carbon dioxide in the exhaust gas into the atmosphere.

[0032] FIG. 6 is a diagram schematically showing the configuration of an exhaust gas supply means according to one embodiment of the present invention. 6, the exhaust gas supply means has an ultrasonic nozzle 23 with an ultrasonic vibrator, and supplies the exhaust gas to the water or concrete supply pipe 15 via the ultrasonic nozzle 23. By using the ultrasonic nozzle 23, the exhaust gas can be supplied in the form of microbubbles, which allows the exhaust gas to be efficiently mixed and reacted with the water or concrete.

[0033] FIG. 7 is a diagram schematically showing the configuration of an exhaust gas supply means according to one embodiment of the present invention. 7, the exhaust gas supply means has an ultrasonic nozzle 25 with an ultrasonic vibrator, and supplies the exhaust gas to a tank 27 storing water via the ultrasonic nozzle 25. By using the ultrasonic nozzle 25, the exhaust gas can be supplied in the form of microbubbles, which allows the water and the exhaust gas to be efficiently mixed and reacted with each other.

[0034] FIG. 8 is a diagram schematically showing the configuration of exhaust gas supply means according to still another embodiment of the present invention. In some embodiments, as shown in Fig. 8, the exhaust gas supply means includes a high-pressure tank 29 and a spray 31. In this case, water is sprayed via the spray 31 into the high-pressure tank 29, which is filled with exhaust gas and has a pressure higher than atmospheric pressure, to mix the water and exhaust gas. By spraying water under a pressure higher than atmospheric pressure, the water and exhaust gas can be efficiently mixed and reacted with each other.

[0035] A precast concrete product according to at least one embodiment of the present invention is manufactured using the manufacturing method described above. In this case, a precast concrete product is produced using the above-described method for producing a precast concrete product, and the concrete absorbs carbon dioxide. The concrete that has absorbed carbon dioxide and been carbonated in this manner has greater strength than conventional non-carbonated concrete, improving the performance of the precast concrete product. On the other hand, it is preferable to use stainless steel, which has high oxidation resistance, or steel that has been treated with anti-rust coating for the raw materials that make up precast concrete products, such as reinforcing bars. This is because carbonation of concrete reduces the alkalinity of precast concrete products, which reduces their oxidation resistance. Anti-rust coatings such as epoxy resin coatings and plating such as zinc plating can be used.

[0036] Finally, the present invention is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications. For example, precast concrete products are not limited to box culverts, but may also be road products (sidewalk slabs, etc.), pipes (RC pipes, etc.), sewerage and irrigation and drainage products (ridge blocks, etc.), retaining wall and embankment products (RC sheet piles, retaining walls, etc.), poles and piles (PC piles, etc.), PC products (PC sleepers, etc.), landscaping products (decorative panels, etc.), other civil engineering products (wave-dissipating blocks, etc.), and building products (hollow concrete blocks, etc.). [Explanation of symbols]

[0037] 1 Mixer 3 Formwork 5 Curing tank 7. Boiler 9. Autoclave 11 Intermediates for precast concrete products 13, 17, 19, 21 Pump 15 Supply pipe 23,25 Ultrasonic nozzle 27 Tank 29 High-pressure tank 31 Spray

Claims

1. a steam curing process in which the formwork in which the concrete has been poured is placed in a steam curing tank, and the concrete is heated while supplying steam into the steam curing tank, thereby hardening the concrete in the formwork to a predetermined strength; an autoclave curing step in which the concrete removed from the formwork after the steam curing step is placed in an autoclave and the concrete is heated while supplying steam into the autoclave; an exhaust gas supplying step of supplying exhaust gas containing carbon dioxide to the concrete or raw materials of the concrete; Equipped with In the exhaust gas supplying step, the exhaust gas is supplied into the steam curing tank so as to supply the exhaust gas containing carbon dioxide to the concrete in the formwork placed in the steam curing tank during the steam curing step. A method for manufacturing a precast concrete product.

2. A mixing step of mixing cement, aggregate, and water to prepare the concrete to be poured into the formwork, In the exhaust gas supplying step, the exhaust gas is dissolved in the water to be mixed with the cement and the aggregate before the mixing step.

2. The method for manufacturing a precast concrete product according to claim 1.

3. a steam curing tank that can accommodate a formwork in which concrete has been poured and heat the formwork with steam; an autoclave capable of accommodating the concrete that has been heated in the steam curing tank and then removed from the formwork, and heating the concrete with steam; an exhaust gas supply means for supplying exhaust gas containing carbon dioxide to the concrete or raw materials of the concrete; Equipped with the exhaust gas supply means is capable of supplying the exhaust gas into the steam curing tank in order to supply the exhaust gas containing carbon dioxide to the concrete in the formwork placed in the steam curing tank, The exhaust gas supply means is further configured to dissolve the exhaust gas in water that is mixed with cement and aggregate to prepare the concrete that is poured into the formwork. A manufacturing device for precast concrete products.

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