A production process for precast concrete components for carbon dioxide curing

Abstract

The present invention discloses a production process for precast concrete components for carbon dioxide curing, comprising the following steps: assembling a hollow frame mold and a complementary mold to form a mold platform plane or a combined mold with an internal mold cavity; injecting mixed concrete into the complete mold cavity or onto the mold platform; curing at room temperature and 100% humidity for a certain period of time, removing the complementary mold to expose the hollowed-out area of the hollow frame mold on the surface of the concrete test block; placing the concrete test block and the hollow frame mold in a carbon dioxide curing apparatus for carbonization curing until the concrete test block reaches the demolding strength, and then removing the hollow frame mold from the surface of the concrete test block. The present invention utilizes a step-by-step demolding method, which allows the component surface to be fully exposed by removing the complementary mold before reaching the demolding strength, allowing the component to dry and fully contact with carbon dioxide. This advances the carbon dioxide curing operation from after demolding to before demolding, making the carbon dioxide curing process practical for production.

Description

Technical Field

[0001] The present invention relates to the technical field of precast concrete components, and in particular to a production process of precast concrete components for carbon dioxide curing. Background Art

[0002] Academic research on CO2-cured precast concrete components has spanned decades. This technology not only effectively improves the early strength of concrete but also consumes significant amounts of CO2, significantly contributing to the goal of carbon neutrality. However, it has yet to be widely adopted in production. This is because research and development related to production applications has focused on curing equipment, such as curing kilns and kettles. These have a significant limitation: precast components must be demolded before they can enter the curing equipment for CO2 curing. This creates a production dilemma, as factories want components to reach demolding strength as quickly as possible for demolding, ensuring rapid mold turnover. CO2 curing, which improves early concrete strength, can achieve this goal. However, demolding now requires CO2 curing, which not only renders curing ineffective but also increases the number of steps and costs. Consequently, the practical application of CO2-cured precast concrete components is rare.

[0003] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0004] In view of the above-mentioned shortcomings, the present invention provides a production process for precast concrete components cured with carbon dioxide. The step-by-step demoulding feature of the present invention allows the component surface to be fully exposed by first removing the complementary mold (the outer mold or the bottom filling mold) before the component reaches the demoulding strength, allowing the component to be dried and fully exposed to carbon dioxide. The carbon dioxide curing operation is advanced from after demoulding to before demoulding, making the carbon dioxide curing process practical for production.

[0005] In order to achieve the above object, the present invention provides a production process for carbon dioxide-cured precast concrete components, comprising the following steps:

[0006] Step 1: Assemble the hollow frame mold and the complementary mold to form a mold table plane or a combined mold with a mold cavity inside;

[0007] Step 2: Pour the mixed concrete into the complete mold cavity or onto the mold platform;

[0008] Step 3: Curing at room temperature and 100% relative humidity for a certain period of time, removing the complementary mold to expose the hollow area of the concrete test block surface corresponding to the hollow frame mold;

[0009] Step 4: Place the concrete test block together with the hollow frame mold into the carbon dioxide curing equipment for carbonization curing, so that the concrete test block reaches the demoulding strength, and remove the hollow frame mold on the surface of the concrete test block.

[0010] According to one aspect of the present invention, before step 4, the method further includes: performing drying pretreatment on the concrete test block together with the hollow frame mold.

[0011] According to one aspect of the present invention, in step 4, the carbonization curing is specifically as follows: carbon dioxide concentration is 100%, air pressure is 1 standard atmosphere, temperature is 60° C., and relative humidity is 60%.

[0012] According to one aspect of the present invention, the drying pretreatment is specifically carried out in an air circulation environment; the specific parameters of the drying pretreatment are: temperature of 60°C, air circulation speed of 1m / s, humidity of 20%, and drying for 1.5-2h.

[0013] According to one aspect of the present invention, the hollow frame mold is assembled by a detachable mechanical connection, such as a slide connection, an extrusion connection, a bolt connection, a clamp clamp, etc.

[0014] According to one aspect of the present invention, a groove is provided on the inner wall of the complementary mold, and the hollow frame mold is embedded in the groove of the complementary mold.

[0015] According to one aspect of the present invention, the hollow frame mold corresponding to the mold cavity and the complementary mold are assembled and placed in a square box.

[0016] According to one aspect of the present invention, the inner wall of the mold cavity or the upper surface of the mold table plane is flat or has a height difference.

[0017] According to one aspect of the present invention, the complementary mold corresponding to the mold cavity is a mold with an open top.

[0018] According to one aspect of the present invention, an opening is provided on any side surface of the square box.

[0019] Beneficial effects of the present invention:

[0020] The step-by-step demoulding feature of the present invention allows the component surface to be fully exposed by first removing the outer mold (complementary mold) before the component reaches the demoulding strength, allowing the component to be dried and fully exposed to carbon dioxide. The carbon dioxide curing operation is advanced from after demoulding to before demoulding, making the carbon dioxide curing process have practical production significance. Compared with existing solutions, the present invention simplifies the process of carbon dioxide curing prefabricated components. Taking composite floor slabs as an example, the demoulding time is shortened from 18 to 24 hours of natural curing in a mild climate to 8 to 12 hours. While maintaining a similar carbon fixation amount, the entire process cycle for achieving carbon fixation of prefabricated components is shortened from 30 to 36 hours to 8 to 12 hours. The mold turnover rate is increased exponentially, the carbon fixation efficiency is significantly increased, and the production cost is greatly reduced. The first step-by-step demoulding is done before the component is finally set, and the mold surface is moist, making demoulding easy. The second demoulding, that is, when the entire component is completely demoulded, the contact area between the component and the mold is small, the adsorption force is low, the demoulding strength requirement is low, and demoulding is also easy. While this method involves an additional step compared to traditional one-shot demolding, the overall demolding difficulty is significantly lower. This allows for earlier demolding, reduces the load requirements on lifting equipment, minimizes the use of forceful demolding during production, and reduces the risk of component damage during demolding, ultimately lowering production costs. The height difference between the two mold layers allows for the creation of relief patterns on the component surface, eliminating the need for an additional pattern base mold compared to other processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the process for producing precast concrete components for carbon dioxide curing according to the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a combined mold with a mold cavity inside after the hollow frame mold and the complementary mold are assembled according to an embodiment of the present invention;

[0023] Figure 3 It is a structural expansion diagram of the mold platform plane after the hollow frame mold and the complementary mold according to an embodiment of the present invention are assembled.

[0024] 1. Inner hollow frame mold; 2. Outer outer mold; 3. Square box; 4. Upper frame mold; 5. Bottom filling mold. DETAILED DESCRIPTION

[0025] To make the present invention easier to understand, the present invention is further described below with reference to specific examples. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, the professional terms used below are consistent with the meanings understood by professional and technical personnel in this field; unless otherwise specified, the raw materials and reagents involved in this article can be purchased from the market or prepared by known methods.

[0026] Because research and development related to production applications has focused on curing equipment such as curing kilns and kettles, these have a significant limitation: precast components must be demolded before entering the curing equipment for CO2 curing. This creates a production dilemma, as factories want components to reach demolding strength as quickly as possible for rapid mold turnover. CO2 curing, which improves concrete's early strength, can achieve this goal. However, demolding has become a prerequisite for CO2 curing, rendering curing ineffective and increasing both process steps and costs.

[0027] In order to solve the above problems, the present invention provides a production process for precast concrete components for carbon dioxide curing, the flow diagram of which is shown in FIG. Figure 1 As shown, the following steps are included:

[0028] Step 1 (molding): Assemble the hollow frame mold and the complementary mold to form a mold table plane or a combined mold with a mold cavity inside;

[0029] Step 2 (Pouring): Pour the mixed concrete into the complete mold cavity or onto the mold platform;

[0030] Step 3 (removing the outer mold): curing at room temperature and 100% relative humidity for a certain period of time, removing the complementary mold to expose the hollow area of the concrete specimen surface corresponding to the hollow frame mold;

[0031] Step 4 (CO2 curing and removing inner frame mold): The concrete test block together with the hollow frame mold is placed in the CO2 curing equipment for carbonization curing, so that the concrete test block reaches the demoulding strength, and the hollow frame mold on the surface of the concrete test block is removed.

[0032] It should be noted that the demoulding strength is determined by the structure, weight, and size of the prefabricated component. For example, 10 MPa can meet the requirements of composite slabs, but this value may not be the case for other types of components, and in many cases, the demoulding strength is lower than that of composite slabs.

[0033] Preferably, before step 4, the method further includes: pre-drying the concrete test block together with the hollow frame mold. It should be noted that this step is not a necessary step, and the test block together with the inner frame mold can be pre-dryed according to the requirements of the concrete formula and the carbonization degree of carbon dioxide.

[0034] Preferably, the concrete test block needs to be processed as a finished product after the frame mold is hollowed out. The finished product processing mainly involves watering and curing at room temperature. In addition, in some cases, the surface of the component needs to be polished, and the exposed steel bars need to be rust-proofed.

[0035] It should be noted that the concentration, pressure, temperature, humidity, and duration of carbonization oxidation are determined based on actual production requirements for strength and carbonization degree. Preferably, in step 4, the carbonization curing is specifically as follows: a carbon dioxide concentration of 100%, an air pressure of 1 standard atmosphere, a temperature of 60°C, and a relative humidity of 60%.

[0036] Preferably, the drying pretreatment is performed in an air-circulating environment; the specific parameters of the drying pretreatment are: temperature of 60°C, air circulation speed of 1 m / s, humidity of 20%, and drying time of 1.5-2 hours. The purpose is to reduce the free water in the concrete by 30%-40%, thereby increasing the depth and speed of carbon dioxide curing.

[0037] In some embodiments of the present invention, the hollow frame mold and the complementary mold are assembled to form a combined mold with a mold cavity inside. Figure 2 As shown, the combined mold includes an inner hollow frame mold 1, an outer shell mold 2 and a square box 3.

[0038] In some embodiments of the present invention, the hollow frame mold and the complementary mold are assembled to form a mold table plane such as Figure 3 As shown, the mold platform plane includes an upper frame mold 4 and a bottom filling mold 5.

[0039] It should be noted that the formwork plane is a steel platform used to produce prefabricated concrete slab components. It can flow on the assembly line or be placed on the ground. When in use, the upper frame mold and the bottom filling mold are assembled to form the formwork plane, and then the side mold of the slab component (a mold commonly used in production) is assembled on the formwork plane, and then it can be cast into shape. Before carbon dioxide curing, the bottom filling mold needs to be removed.

[0040] Preferably, the hollow frame mold and the complementary mold are spliced together by the pressure of the square box or the gravity of the upper frame mold.

[0041] Preferably, the hollow frame mold is joined by detachable mechanical connection or hot melt adhesive connection. The detachable mechanical connection includes: slide connection, extrusion connection, bolt connection, clamp clamping, etc.

[0042] Exemplarily, the hollow frame mold includes a bottom frame and a side frame. Holes are provided at the four corners of the bottom frame and the side frame. When assembling, fine nails are used to connect them through the positions of the holes.

[0043] Preferably, the inner wall of the complementary mold is provided with a groove, and the hollow frame mold is embedded in the groove of the complementary mold.

[0044] Preferably, the hollow frame mold corresponding to the mold cavity and the complementary mold are assembled and placed in a square box. It should be noted that the square box is used to wrap the assembled mold to prevent the assembled mold from deforming after pouring concrete.

[0045] Preferably, the inner wall of the mold cavity or the upper surface of the mold base plane is flat or has height differences. It should be noted that the purpose of a flat surface is to produce a flat component surface; the purpose of a surface with height differences is to produce a relief texture or a rough surface. The rough surface facilitates plastering during renovation.

[0046] Preferably, the complementary mold corresponding to the mold cavity is a mold with an open top, which is convenient for introducing the mixed concrete into the mold cavity.

[0047] Preferably, any side surface around the square box is provided with an opening, the purpose of which is to facilitate the subsequent removal of the square box.

[0048] Example 1

[0049] First, the molds are assembled. A release agent is sprayed on the hollow frame mold (inner hollow frame mold or upper frame mold) and the complementary mold (outer mold or bottom filling mold). After the molds are installed, concrete is poured normally. After pouring, the complementary mold (outer mold or bottom filling mold) is removed, leaving the hollow frame mold (inner hollow frame mold or upper frame mold) exposed on all sides and the bottom of the concrete test block. A pre-drying treatment is performed in an air-circulating environment (drying oven) (temperature 60°C, air circulation speed 1m / s, humidity of approximately 20% for 2 hours). For example, after the upper frame mold and bottom filling mold are assembled and concrete is poured to prepare a composite floor slab, the test block and the inner frame mold are placed in a carbon dioxide curing equipment for carbonization curing. Curing is carried out in a curing room at 100% carbon dioxide concentration, 1 standard atmosphere, temperature 60°C, and relative humidity of 60% for 4 hours. The test block reaches a compressive strength of approximately 10 MPa, meeting the demoulding requirements. In this embodiment, the total curing time is 8 hours before demoulding.

[0050] Comparative Example 1

[0051] The composite floor slab of the same size as Example 1 is prepared using the production process of precast concrete components actually produced in the existing production, specifically: curing for 24 hours under normal temperature conditions above 15°C, and then demoulding; when the evaporation rate is high, it is necessary to sprinkle water on the surface of the component, and when the temperature is too low, it is necessary to cover it with geotextile for heat preservation and water retention. Precast concrete can be steam cured to shorten the demoulding time. The general process is to stand still for 4-6 hours at normal temperature, and then enter the curing kiln for steam curing. The steam curing temperature generally does not exceed 65°C, the humidity is 100%, and curing for 8 to 12 hours can achieve demoulding. That is, the time to reach the demoulding strength of the above-mentioned normal temperature curing and steam curing (18 to 24 hours) is relatively long. And when standing still in a normal temperature environment, it is necessary to combine the evaporation rate to carry out water sprinkling or heat preservation on the surface of the component, that is, the process is complicated. Carbon dioxide curing is a process after demoulding.

[0052] Comparative Example 2

[0053] The composite floor slab of the same size as Example 1 was prepared using the existing laboratory carbon dioxide curing concrete test block process, specifically: after pouring the concrete, it was cured at room temperature of 25°C and humidity of 50% for 5 hours, and the mold was removed after final setting (this is completely different from the demoulding in the production sense. At this time, the test block has no compressive strength and the mold is carefully removed from the test block by hand); drying pretreatment (temperature of 25°C, air circulation speed of 1m / s, humidity of about 50% for 5 hours); carbonization curing for 12 hours under 100% concentration of CO2 and 5 standard atmospheres; 4. Moist curing in an environment of 25°C and humidity of 95% until the required compressive strength test is carried out. The above experimental demoulding cannot be used in actual production, and carbon dioxide curing is performed after demoulding.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A production process for precast concrete components for carbon dioxide curing, characterized in that: The following steps are involved: Step 1: Assemble the hollow frame mold and the complementary mold to form a mold table plane or a combined mold with a mold cavity inside; Step 2: Pour the mixed concrete into the complete mold cavity or onto the mold platform; Step 3: Curing at room temperature and 100% relative humidity for a certain period of time, removing the complementary mold to expose the hollow area of the concrete test block surface corresponding to the hollow frame mold; Step 4: Place the concrete test block together with the hollow frame mold into the carbon dioxide curing equipment for carbonization curing, so that the concrete test block reaches the demoulding strength, and remove the hollow frame mold on the surface of the concrete test block.

2. The production process of precast concrete components for carbon dioxide curing according to claim 1, characterized in that: Before step 4, the method further includes: performing drying pretreatment on the concrete test block and the hollow frame mold.

3. The process for producing precast concrete components cured with carbon dioxide according to claim 1, characterized in that: In step 4, the carbonization curing is specifically as follows: carbon dioxide concentration is 100%, air pressure is 1 standard atmosphere, temperature is 60° C., and relative humidity is 60%.

4. The production process of precast concrete components for carbon dioxide curing according to claim 2, characterized in that: The drying pretreatment is specifically carried out in an air circulation environment; the specific parameters of the drying pretreatment are: temperature of 60° C., air circulation speed of 1 m / s, humidity of 20%, and drying for 1.5-2 hours.

5. The production process of precast concrete components for carbon dioxide curing according to claim 1, characterized in that: The hollow frame mold is assembled through a detachable mechanical connection.

6. The production process of precast concrete components for carbon dioxide curing according to claim 1, characterized in that: The inner wall of the complementary mold is provided with a groove, and the hollow frame mold is embedded in the groove of the complementary mold.

7. The production process of precast concrete components for carbon dioxide curing according to claim 1, characterized in that: The hollow frame mold corresponding to the mold cavity and the complementary mold are assembled and placed in a square box.

8. The production process of precast concrete components for carbon dioxide curing according to claim 1, characterized in that: The inner wall of the mold cavity or the upper surface of the mold table plane is flat or has a height difference.

9. The production process of precast concrete components for carbon dioxide curing according to claim 1, characterized in that: The complementary mold corresponding to the mold cavity is a mold with an open upper end.

10. The production process of precast concrete components for carbon dioxide curing according to claim 7, characterized in that: Any side surface of the square box is provided with an opening.

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