Curing device and curing method

Abstract

To provide a curing device and curing method that can make a concrete product high in strength and durability while restraining a used amount of carbon dioxide with a simple configuration.SOLUTION: A curing device 1 is used in curing of a concrete product C containing a carbonation admixture. The curing device 1 comprises a proof pressure box body 2 accommodating the concrete product C and dry ice D, a safety valve 7 for maintaining internal and external pressure difference of the proof pressure box body 2 at first predefined pressure, and an introduction valve 8 for introducing an atmosphere outside the proof pressure box body 2 into the proof pressure box body 2 by external pressure more than or equal to second predefined pressure with higher pressure than the first predefined pressure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a curing apparatus and a curing method used for curing concrete products containing an admixture that cures by adsorbing carbon dioxide.

Background Art

[0002] Conventionally, in precast concrete products, for example, an apparatus is known in which a predetermined amount of an admixture mainly composed of dicalcium silicate γ-phase (hereinafter γC2S) is contained, and this γC2S is reacted with carbon dioxide gas by carbonation curing to densify the surface layer portion of the product and exhibit high strength and high durability performance. For example, a shielding body in which a precast concrete product is housed is provided with a gas inlet connected to a carbon dioxide gas supply source and a gas outlet connected to a carbon dioxide trap mechanism, and adjustment mechanisms are provided at the gas inlet and the gas outlet, respectively. By interlocking these adjustment mechanisms, a mode of increasing the carbon dioxide gas concentration in the shielding space in the shielding body and a mode of controlling the carbon dioxide gas concentration in the shielding space to a steady state are implemented to forcibly carbonate the surface layer portion of the precast concrete product. (For example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the case of the above-described curing apparatus, since it has a large-scale and complex structure such that a carbon dioxide gas supply source and a carbon dioxide trap mechanism are connected to the curing tank via pipes, not only is the handling poor, but also when scaled up, a large amount of carbon dioxide gas is used and management is difficult, so it is not a configuration suitable for industrialization.

[0005] Furthermore, there is an increasing demand for even higher strength and durability in precast concrete products cured with carbonation.

[0006] In view of such circumstances, the present invention aims to provide a curing apparatus and a curing method that can increase the strength and durability of concrete products while suppressing the amount of carbon dioxide used with a simple configuration.

Means for Solving the Problems

[0007] The curing apparatus according to claim 1 is a curing apparatus used for curing a concrete product containing a carbonation admixture, comprising: a pressure-resistant container that houses the concrete product and dry ice; a safety valve for maintaining the internal and external pressure difference of the pressure-resistant container at a first predetermined pressure; and an introduction valve for introducing the atmosphere outside the pressure-resistant container into the pressure-resistant container by an external pressure equal to or higher than a second predetermined pressure, which is higher than the first predetermined pressure.

[0008] The curing apparatus according to claim 2 is the curing apparatus according to claim 1, wherein the pressure-resistant container separately has a main body chamber to which the safety valve and the introduction valve are connected and in which the concrete product is housed, and a charging chamber into which dry ice is charged.

[0009] The curing apparatus according to claim 3 is the curing apparatus according to claim 2, wherein the charging chamber includes a communication port that communicates with the main body chamber and an opening / closing body that opens and closes the communication port, and the opening / closing body supports dry ice in a state where the communication port is closed and operates to open the communication port when the pressure in the charging chamber becomes a third predetermined pressure that is smaller than the first predetermined pressure.

[0010] The curing apparatus according to claim 4 is the curing apparatus according to claim 1, further comprising a discharge valve for discharging condensed water in the pressure-resistant container.

[0011] The curing method according to claim 5 uses the curing device according to any one of claims 1 to 4, installs the curing device in which the internal atmosphere is filled with carbon dioxide by sublimation of dry ice contained in a pressure-resistant container in a pressure vessel for autoclave curing, and performs autoclave curing in the pressure vessel.

Effect of the Invention

[0012] According to the present invention, with a simple configuration, while suppressing the amount of carbon dioxide used, concrete products can be made to have higher strength and higher durability.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Embodiment for Carrying Out the Invention

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] In FIG. 1, reference numeral 1 denotes a curing device. The curing device 1 is used for curing a concrete product C. Here, the concrete product C is a precast concrete product and contains a carbonation admixture that cures by adsorbing carbon dioxide. The carbonation admixture has, as an example, dicalcium silicate γ-phase (γC2S) as a main component. The concrete product C is preferably a precast non-reinforced concrete product in order to prevent a decrease in the durability of the reinforcing bars due to the neutralization of concrete by carbonation curing (carbon dioxide curing) described later. For example, SUICOM (registered trademark) or the like is used as the concrete product C.

[0016] The curing device 1 has a pressure-resistant container 2 that houses the concrete product C. The pressure-resistant container 2 has a structure that can withstand a predetermined internal and external pressure, for example, an internal and external pressure of 2.0 kgf / cm 2 and is made of, for example, steel.

[0017] The pressure-resistant container 2 is a small hollow cylindrical container. Inside the pressure-resistant container 2, a main body chamber 3 that houses the concrete product C and a charging chamber 4 that houses dry ice D, which is a source of carbon dioxide gas for curing the concrete product C, are separately formed (as separate chambers).

[0018] The main body chamber 3 is hermetically formed inside the pressure-resistant container 2. In the present embodiment, the main body chamber 3 is, for example, cylindrical with a diameter of 400 mm and a height of 600 mm, and its volume is set to approximately 75 L. Inside the main body chamber 3, a support 6 for supporting the concrete product C is arranged. As the support 6, for example, a wire mesh or the like is used.

[0019] A safety valve 7 is connected to the main body chamber 3. The safety valve 7 is for maintaining the internal and external pressure difference of the main body chamber 3 at a first predetermined pressure by opening when the pressure in the pressure-resistant container 2, that is, the main body chamber 3, becomes equal to or higher than the first predetermined pressure compared to the external pressure and releasing the atmosphere inside the main body chamber 3 to the outside. The first predetermined pressure is set to be greater than atmospheric pressure, for example, 1.5 kgf / cm 2 is set. The safety valve 7 is connected, for example, to the upper part of the main body chamber 3.

[0020] Also, an introduction valve 8 is connected to the main body chamber 3. The introduction valve 8 is for introducing the atmosphere outside the pressure-resistant container 2, that is, outside the main body chamber 3, into the pressure-resistant container 2, that is, into the main body chamber 3. The introduction valve 8 is set to open by an external pressure equal to or higher than a second predetermined pressure that is higher than the first predetermined pressure. The second predetermined pressure is set to be smaller than the maximum value of the saturated steam pressure (maximum saturated steam pressure) that is raised during autoclave curing, which will be described later, and is, for example, 2.0 kgf / cm 2 is set. The introduction valve 8 is connected, for example, to the upper part of the main body chamber 3.

[0021] Preferably, a discharge valve 9 for discharging the condensed water in the pressure-resistant housing 2, that is, in the main body chamber 3, is connected to the main body chamber 3. The discharge valve 9 is opened and closed manually or automatically when necessary. The discharge valve 9 is connected to the lower part of the main body chamber 3.

[0022] Furthermore, preferably, a pressure measuring device 10 for measuring the pressure in the main body chamber 3 and a carbon dioxide concentration measuring device 11 for measuring the carbon dioxide concentration in the main body chamber 3 are respectively arranged in the main body chamber 3.

[0023] The charging chamber 4 communicates with the main body chamber 3 and is hermetically formed in the pressure-resistant housing 2. The charging chamber 4 is set to have a smaller volume than the main body chamber 3. The charging chamber 4 is basically set to have a relatively small volume with respect to the main body chamber 3 as long as it can accommodate an amount of dry ice D that can fill the main body chamber 3 with carbon dioxide at a predetermined pressure. The charging chamber 4 is located, for example, above the main body chamber 3.

[0024] The charging chamber 4 includes a charging port 15 that communicates with the outside of the pressure-resistant housing 2 and through which dry ice D is charged from the outside of the pressure-resistant housing 2, and a communication port 16 that communicates with the main body chamber 3.

[0025] The charging port 15 can be opened and closed by a lid body 17. The lid body 17 is preferably a double-opening lid, for example, so that the carbon dioxide generated by the sublimation of the dry ice D does not leak from the charging chamber 4.

[0026] The communication port 16 can be opened and closed by an opening / closing body 18. The opening / closing body 18 is a lid that supports the dry ice D in the charging chamber 4 with the communication port 16 closed. When the pressure in the charging chamber 4 sealed by the lid body 17 and the opening / closing body 18 reaches a third predetermined pressure due to the sublimation of the dry ice D, the opening / closing body 18 opens the communication port 16 and operates to introduce the dry ice D and the carbon dioxide generated by its sublimation into the main body chamber 3 from the communication port 16. The third predetermined pressure is smaller than the first predetermined pressure and is set to, for example, atmospheric pressure (≈0.1 MPa). In the present embodiment, according to the process sequence of the curing method described later, the first predetermined pressure is set between the second predetermined pressure and the third predetermined pressure.

[0027] Preferably, the pressure-resistant housing 2 is divided into a plurality of housing parts. In the present embodiment, the pressure-resistant housing 2 is divided into a first housing part 20 and a second housing part 21. The first housing part 20 and the second housing part 21 are configured to seal the main body chamber 3 in a state of being fixed to each other by fixing means 22 such as a detachable mechanism fastener.

[0028] The first housing part 20 is a lower housing part (lower housing structure) in the present embodiment. The first housing part 20 has a cylindrical outer wall 25, a circular bottom part 26 that closes the lower end part of the outer wall 25, and a leg part 27 that extends from the outer wall 25.

[0029] The outer wall 25 constitutes the lower part of the side part of the main body chamber 3. A support body 6 is disposed at a position near the lower part inside the outer wall 25 and above the bottom part 26.

[0030] The bottom part 26 constitutes the bottom of the main body chamber 3. The bottom part 26 is curved so as to gradually sink downward from the peripheral part toward the central part. A discharge valve 9 is connected to the bottom part 26. For example, the discharge valve 9 is located at the central part of the bottom part 26.

[0031] The leg part 27 is for supporting the pressure-resistant housing 2 on the installation part. The leg part 27 also has a function as a protection part (lower protection plate) that is positioned to cover and protect the outside of the discharge valve 9.

[0032] The second housing part 21 is an upper housing part (upper lid structure) in the present embodiment. The second housing part 21 has a cylindrical outer wall 30, a circular lid part 31 that closes the outer wall 30, and a protection part 32 that extends from the outer wall 30.

[0033] The outer wall 30 constitutes the upper part of the side part of the main body chamber 3. It has a diameter dimension equal to or substantially equal to that of the outer wall 25 of the first housing part 20. The lower end part of the outer wall 30 of the second housing part 21 and the upper end part of the outer wall 25 of the first housing part 20 are butted against each other and fixed to each other by the fixing means 22, so that the main body chamber 3 is sealed.

[0034] The lid portion 31 forms the upper part of the main body chamber 3. The lid portion 31 is curved so as to gradually project upward from the peripheral portion toward the central portion. A safety valve 7, an introduction valve 8, a pressure measuring device 10, and a carbon dioxide concentration measuring device 11 are connected to the lid portion 31. For example, the safety valve 7 is located at the central portion of the lid portion 31. Further, a partition portion 35 that partitions the charging chamber 4 inside is connected to the lid portion 31. The partition portion 35 is formed in a cylindrical shape, for example, and is disposed so as to penetrate the lid portion 31. That is, the upper portion of the partition portion 35 extends above the lid portion 31, and the lower portion of the partition portion 35 extends below the lid portion 31. The upper end portion of the partition portion 35 is the charging port 15, the lower end portion of the partition portion 35 is the communication port 16, and a lid body 17 and an opening / closing body 18 are attached inside the partition portion 35.

[0035] The protection portion 32 is located so as to cover the outside of the safety valve 7, the introduction valve 8, the pressure measuring device 10, the carbon dioxide concentration measuring device 11, and the partition portion 35 to protect them.

[0036] And the curing device 1 can be installed in a pressure vessel 40 for autoclave curing. The pressure vessel 40 is a large openable and closable container, also called an autoclave body, and is a hermetically sealed pressure-resistant container that can withstand the pressure during autoclave curing. The pressure vessel 40 encloses saturated steam and can control the internal pressure and temperature. Further, the pressure vessel 40 is provided with a pressure gauge, a safety valve, and the like. The curing device 1 and the pressure vessel 40 constitute a curing system.

[0037] In the present embodiment, the pressure vessel 40 is formed in a cylindrical shape having a diameter dimension capable of accommodating the entire curing device 1. The pressure vessel 40 has, for example, the axial direction as the longitudinal direction and is installed with the axial direction in a horizontal state. For example, the pressure vessel 40 is set to a diameter of 3 m and a length of 31 m. Further, inside the pressure vessel 40, a conveying device such as a rail for sending a placing object on which an object to be cured is placed into the pressure vessel 40 or carrying it out from the inside of the pressure vessel 40 is arranged along the axial direction at the lower part.

[0038] Next, a curing method according to an embodiment will be described.

[0039] First, place the pre-formed concrete product C in the pressure-resistant container 2 of the curing device 1. The pressure-resistant container 2 removes the second container part 21 from the first container part 20 and places the concrete product C on the support 6 in the first container part 20.

[0040] Next, cover the first container part 20 with the second container part 21 and fix the first container part 20 and the second container part 21 with the fixing means 22 to seal the main body chamber 3 containing the concrete product C.

[0041] With this sealing confirmed, open the lid 17 on the second container part 21, put dry ice D into the charging chamber 4 from the opened charging port 15, and close the lid 17 while supporting the dry ice D on the opening / closing body 18 that closes the communication port 16. Note that the dry ice D to be charged expands in volume by about 750 times due to sublimation. In this embodiment, in order to make the pressure in the main body chamber 3 (volume about 75L) 1.5 kgf / cm 2 Therefore, 75 / 750×2 = 0.2L = 200cc of dry ice D is charged.

[0042] When the dry ice D sublimates in the charging chamber 4 and the pressure in the charging chamber 4 exceeds a third predetermined pressure, for example, 0.1 MPa, the opening / closing body 18 that supports the dry ice D operates to open the communication port 16, and the dry ice D is introduced into the main body chamber 3 through the communication port 16. By making the opening / closing body 18 open at such a small pressure, the partition part 35 and the like constituting the charging chamber 4 do not require the function of a pressure-resistant container, and the cost can be suppressed. The introduced dry ice D falls on the support 6 and continues to sublimate.

[0043] When the pressure of the carbon dioxide gas generated by the sublimation of the dry ice D in the main body chamber 3 reaches a first predetermined pressure, for example, 1.5 kgf / cm 2When the pressure exceeds atmospheric pressure by a small amount as described above, the safety valve 7 opens. First, the air present in the main body chamber 3 escapes to the outside of the main body chamber 3, and then carbon dioxide gas begins to escape to the outside of the main body chamber 3. At this point, the main body chamber 3 is filled with carbon dioxide gas at a first predetermined pressure, and the initial carbonation curing has started. The processes up to this point are basically carried out under atmospheric pressure.

[0044] In this state, the curing device 1 is transported into the pressure vessel 40 and installed, the pressure vessel 40 is sealed, and high-temperature saturated steam is sent in to start autoclave curing within the pressure vessel 40.

[0045] In autoclave curing, a temperature increase process, a pressure increase process, a holding process, a pressure reduction process, and a temperature reduction process are carried out. An example of the conditions for each process of autoclave curing is shown in FIGS. 2 and 3. In FIG. 3, P indicates the change in pressure, and T indicates the change in temperature.

[0046] In the pressure increase process, when the pressure inside the pressure vessel 40 exceeds a second predetermined pressure, for example, 2.0 kgf / cm 2 the inlet valve 8 of the curing device 1 opens, and the pressure inside the pressure vessel 40 and the above are introduced into the main body chamber 3 of the curing device 1 through the inlet valve 8. Therefore, the same autoclave curing conditions are set between the inside of the main body chamber 3 of the curing device 1 and the inside of the pressure vessel 40. Inside the main body chamber 3, the partial pressure of carbon dioxide gas decreases slightly as part of the carbon dioxide gas is absorbed by the water vapor, and for example, the partial pressure of carbon dioxide gas is about 1 atm, the partial pressure of water vapor is about 9 atm, and the total pressure is about 10 atm. Therefore, in the main body chamber 3, carbonation curing by carbon dioxide gas and autoclave curing are carried out simultaneously.

[0047] When the autoclave curing is completed, the pressure vessel 40 is opened, the curing device 1 is taken out, and further, the fixing by the fixing means 22 is released to remove the second container part 21 from the first container part 20, and the concrete product C is taken out from the main body chamber 3. Also, the discharge valve 9 is opened to discharge the condensed water that has condensed inside the pressure-resistant container 2 and has collected on the bottom 26.

[0048] Thus, according to this embodiment, a pressure-resistant container 2 for accommodating a concrete product C and dry ice D is provided with a safety valve 7 for maintaining the internal and external pressure difference thereof at a first predetermined pressure, and an introduction valve 8 for introducing the atmosphere outside the pressure-resistant container 2 into the pressure-resistant container 2 by an external pressure equal to or higher than a second predetermined pressure higher than the first predetermined pressure. By doing so, since it is not necessary to connect piping or the like for supplying and discharging carbon dioxide to the pressure-resistant container 2, the configuration becomes simple, not only is the handling of the curing device 1 improved, but also the safety valve 7 can be efficiently operated using dry ice D to fill the pressure-resistant container 2 with only the necessary amount of carbon dioxide. Therefore, it becomes possible to perform carbonation curing while suppressing the amount of carbon dioxide used.

[0049] The introduction valve 8 sets the second predetermined pressure to, for example, 2.0 kgf / cm 2 (≈0.2 MPa), thereby enabling the autoclave curing atmosphere to be realized early and allowing the autoclave curing to be simultaneously started promptly from the initial carbonation curing.

[0050] Then, for example, the curing device 1 filled with carbon dioxide is installed in a pressure vessel 40 for autoclave curing, and autoclave curing is performed in the pressure vessel 40. Thus, the autoclave curing atmosphere can be introduced into the pressure-resistant container 2 by the introduction section 8 via the introduction valve 8. Therefore, carbonation curing and autoclave curing can be simultaneously performed on the concrete product C. Accordingly, the concrete product C can be efficiently cured in a short time, and the use of unnecessary carbon dioxide can be avoided by performing carbonation curing by piggybacking on the autoclave curing flow.

[0051] That is, using the large pressure vessel 40 itself as a carbonation curing container would result in the use of a large amount of carbon dioxide or exhaust gas, and management would not be easy. On the other hand, by enabling carbonation curing for the small pressure-resistant container 2 using dry ice D, autoclave curing can also be easily achieved by installing the pressure-resistant container 2 in the pressure vessel 40.

[0052] The concrete product C manufactured according to this embodiment can achieve, due to the strength increase by carbonation curing and the strength increase by autoclave curing (pozzolanic reaction), for example, a large compressive strength compared to the compressive strength (40 - 50 N / mm 2 ) when the concrete product C is normally cured, such as a compressive strength about 1.5 times as large, for example, a compressive strength of 60 - 80 N / mm 2 ), which can be developed early. Therefore, it is possible to manufacture a concrete product C with higher strength and higher durability.

[0053] Also, by increasing the size of the pressure - resistant container 2 to a size that can be placed in the pressure vessel 40, it is possible to increase the size of the concrete product C.

[0054] By separately forming the main body chamber 3 for accommodating the concrete product C in the pressure - resistant container 2 and the charging chamber 4 into which dry ice D is charged, the timing of closing the main body chamber 3 by the fixing means 22 and the timing of starting carbonation curing by carbon dioxide generated by the sublimation of dry ice D can be managed separately.

[0055] Since the charging chamber 4 is a small chamber with a smaller volume than the main body chamber 3, it is possible to keep the degree of sublimation of dry ice D in the chamber to a minimum.

[0056] Furthermore, by making the communication port 16 connecting the charging chamber 4 and the main body chamber 3 openable and closable by an opening - closing body 18, supporting dry ice D in a state where the opening - closing body 18 closes the communication port 16, and operating such that the opening - closing body 18 opens the communication port 16 when the pressure in the charging chamber 4 becomes a third predetermined pressure smaller than the first predetermined pressure, it becomes possible to safely and surely charge dry ice D into the main body chamber 3 of the pressure - resistant container 2.

[0057] By providing a discharge valve 9 for discharging the condensed water in the pressure - resistant container 2, the condensed water generated at the stage when the autoclave curing is completed can be easily discharged from the pressure - resistant container 2 (main body chamber 3) by the discharge valve 9.

Explanation of Reference Numerals

[0058] 1 Curing device 2 Pressure-resistant housing 3 Main body chamber 4 Feed chamber 7 Safety valve 8 Introduction valve 9 Discharge valve 16 Communication port 18 Closing body 40 Pressure vessel C Concrete product D Dry ice

Claims

1. A curing device used for curing a concrete product containing a carbonated admixture, a pressure-resistant container for housing the concrete product and dry ice, a safety valve for maintaining the internal and external pressure difference of the pressure-resistant container at a first predetermined pressure, an introduction valve for introducing the atmosphere outside the pressure-resistant container into the pressure-resistant container by an external pressure equal to or higher than a second predetermined pressure higher than the first predetermined pressure, and characterized by comprising the above.

2. The pressure-resistant container has a main body chamber to which the safety valve and the introduction valve are connected and in which the concrete product is housed, and a charging chamber into which dry ice is charged, separately, The curing device according to claim 1, characterized by the above.

3. The charging chamber has a communication port communicating with the main body chamber, and an opening / closing body for opening and closing the communication port, The opening / closing body supports dry ice in a state where the communication port is closed, and operates to open the communication port when the pressure in the charging chamber becomes a third predetermined pressure smaller than the first predetermined pressure. The curing device according to claim 2, characterized by the above.

4. and characterized by comprising a discharge valve for discharging condensed water in the pressure-resistant container. The curing device according to claim 1, characterized by the above.

5. Using the curing device according to any one of claims 1 to 4, installing the curing device in which the internal atmosphere is filled with carbon dioxide by sublimation of dry ice housed in a pressure-resistant container into an autoclave curing pressure vessel, and performing autoclave curing in the pressure vessel. A curing method characterized by the above.

Images