Intelligent electric heat insulation formwork system for winter construction concrete and construction method

Abstract

This invention discloses an intelligent electric heating and insulation formwork system for concrete construction in winter, comprising a composite structure and an intelligent temperature control unit. The composite structure includes a steel formwork base, with an insulation layer on one side and an insulating and heat-resistant layer, a heating circuit layer, and a detachable protective panel sequentially arranged on the other side. The heating circuit layer is electrically connected to the intelligent temperature control unit. This invention proposes an integrated formwork system that integrates high-efficiency insulation materials, advanced heating elements, and steel formwork in a modular design, achieving intelligent control and high reusability, filling a gap in the industry.

Description

Technical Field

[0001] This invention relates to the field of formwork technology, specifically to an intelligent electric heating and insulation formwork system and construction method for concrete in winter construction. Background Technology

[0002] With the rapid development of infrastructure construction in my country, winter construction has become the norm in engineering projects. In the Phoenix Yellow River Avenue South Extension Project, the applicant needs to carry out concrete pouring for bridge abutments, piers, and cap beams during the winter. The low temperatures in winter severely impact concrete quality. When the ambient temperature is below 5℃, the hydration reaction rate of concrete slows down significantly; when the temperature is below 0℃, the free water inside the concrete freezes, causing the hydration reaction to stop and resulting in volume expansion, severely reducing concrete strength and even causing structural damage.

[0003] Currently, the commonly used methods for thermal insulation and curing of concrete during winter construction mainly include: 1. Heat storage and insulation method: Covering the exposed concrete surface with materials such as plastic film, cotton quilt, and straw mat for insulation. This method is simple and easy to implement, but the insulation effect is limited. Under extremely cold conditions (below -10℃), it is difficult to guarantee the core temperature of the concrete. In addition, the covering is prone to moisture, which reduces its insulation performance and requires frequent replacement, generating a large amount of waste.

[0004] 2. External heating method: This method uses hot air blowers, steam curing equipment, etc., to heat the space surrounding the concrete structure. While this method offers relatively good heating results, it is energy-intensive, has low thermal efficiency (typically below 40%), poor temperature uniformity, requires complex equipment, is difficult to arrange flexibly on-site, and poses safety hazards.

[0005] 3. Built-in electric heating method: Electric heating elements such as heating wires or electric blankets are laid in the formwork. For example, the electric heating and insulation system for steel truss floor decks disclosed in prior art CN113216482B. These methods provide an active heat source, but generally suffer from problems such as poor durability of the heating elements, poor bonding with the concrete formwork, uneven heating, low thermal efficiency, inability to reuse, or high cost of reuse.

[0006] 4. Composite formwork method: A polyurethane foam insulation layer is sprayed onto the outside of the steel formwork to form a composite insulation formwork. This method improves the insulation performance, but lacks active heating capacity and is still insufficient at extreme low temperatures, and cannot actively regulate the curing temperature of the concrete.

[0007] Existing technologies mostly focus on single-function insulation or heating. A comprehensive solution that integrates high-efficiency insulation materials, advanced heating elements, and steel formwork into a modular design, achieving intelligent control and high reusability, is still lacking. This is particularly true in large-scale linear projects like the "Phoenix Yellow River Avenue South Extension Project," where there is an urgent need for winter construction equipment that is rapidly reusable, highly reliable, energy-efficient, and environmentally friendly. Summary of the Invention

[0008] The main technical task of this invention is to address the shortcomings of the existing technology by providing an intelligent electric heating insulation formwork system and construction method for concrete in winter construction, thereby solving the problems of poor insulation effect, high energy consumption, non-reusability, and inaccurate temperature control in traditional winter concrete construction and curing techniques.

[0009] The technical solution of this invention is as follows: Intelligent electric heating and insulation formwork system for concrete construction in winter, including composite structure and intelligent temperature control unit; The composite structure includes a steel formwork base, with an insulation layer on one side and an insulating and heat-insulating layer, a heating circuit layer, and a removable protective panel on the other side in sequence. The heating circuit layer is electrically connected to the intelligent temperature control unit.

[0010] As one implementation method, the insulation layer is made of rigid polyurethane foam, which is tightly attached to the outer surface of the steel formwork substrate by high-pressure spraying or casting molding process.

[0011] In one implementation, the heating circuit layer is bonded to the surface of the insulating and heat-insulating layer through a high-temperature curing process. The heating circuit layer uses graphene-modified polytetrafluoroethylene composite material as a flexible substrate, and a conductive circuit is formed on it using printing or etching processes.

[0012] In one embodiment, the protective panel covers the heating circuit layer and is detachably connected to the steel template base, and the surface of the protective panel is smooth.

[0013] As one implementation method, the intelligent temperature control unit includes a temperature sensor group, a microprocessor controller, a power module, and a human-machine interface; The temperature sensor group includes at least a pre-embedded sensor embedded in the concrete and a sensor attached to the inner surface of the steel formwork substrate. The microprocessor controller can dynamically adjust the power output to the circuit layer based on the preset maintenance temperature curve and the real-time temperature data through the PID algorithm.

[0014] This invention also provides a construction method for intelligent electric heating insulation formwork for concrete in winter construction, using the above-mentioned intelligent electric heating insulation formwork system, with the following specific steps: Step 1: Template assembly and sensor installation; Multiple composite insulation templates are assembled into the required large template system using standardized connectors; When tying the reinforcing bars, the water-resistant temperature sensor probe is fixed inside the reinforcing mesh beforehand, and the wire is led out. Step 2: System Connection and Preheating; After the template is installed in place, connect each wire of the temperature sensor group to the intelligent temperature control unit, and connect the heating circuit of each template to the output terminal of the temperature control unit in parallel. Step 3: Concrete pouring and curing setup; Pour concrete and set curing parameters through the human-machine interface of the intelligent temperature control unit; Step 4: Intelligent closed-loop control; During the curing period, the intelligent temperature control unit compares the measured values ​​of the sensors with the target values ​​in real time, and dynamically adjusts the output power through the PID algorithm to keep the core temperature and surface temperature of the concrete within the set range. Step 5: System shutdown and template removal; After curing is completed, the system automatically stops heating. Once the concrete strength reaches the required level, the formwork is removed, the protective panel surface is cleaned, and the concrete is transferred to the next construction section for reuse.

[0015] Preferably, in step one, temperature sensor probes are pre-embedded at different depths on the inner side of the steel mesh.

[0016] Preferably, in step two, before pouring concrete, the formwork preheating program is started to raise the temperature inside the formwork to above 5°C.

[0017] The maintenance parameters in step three include the target temperature range and the maintenance cycle.

[0018] Through the above design, the intelligent electric heating and insulation formwork system and construction method for winter construction concrete of the present invention, compared with the prior art, proposes an integrated formwork system that integrates high-efficiency insulation materials, advanced heating elements and steel formwork into a modular design, and realizes intelligent control and high reusability, filling a gap in the industry.

[0019] The template adopts a standardized design, allowing for rapid assembly and operation upon power connection, simplifying the tedious processes of covering, wrapping, and monitoring during winter construction. Intelligent temperature control reduces the workload of manual inspection and adjustment, improving construction efficiency. Furthermore, the intelligent temperature control unit achieves closed-loop control through a PID algorithm, with a temperature control accuracy of ±1℃, ensuring the quality of concrete curing.

[0020] The multi-layered structure design of the formwork system ensures electrical insulation and fire safety. The formwork can be customized in size and shape according to project requirements. It is not only suitable for structures such as bridge abutments, piers, and cap beams, but also for winter construction of concrete structures such as tunnel sidewalls, cast-in-place floor slabs, and walls.

[0021] This invention uses rigid polyurethane foam as an insulation layer on the back of the steel formwork substrate, which greatly reduces heat loss. The reusable design reduces the use of traditional disposable insulation materials such as cotton quilts and electric blankets, reducing construction waste by more than 90% and meeting the requirements of green construction. Attached Figure Description

[0022] In the attached diagram: Figure 1 This is a structural schematic diagram of the thermal insulation template system; Figure 2 A schematic diagram of the layout of a graphene-based flexible heating circuit layer; Figure 3 This is a block diagram illustrating the working principle of the intelligent temperature control unit. The components represented by the various reference numerals in the diagram are: 1. Steel formwork base; 2. Insulation layer; 3. Thermal insulation layer; 4. Heating circuit layer; 5. Protective panel. Detailed Implementation

[0023] Example 1 See Figure 1 This embodiment provides an intelligent electric heating and insulation formwork system for concrete construction in winter, including a composite structure and an intelligent temperature control unit; The composite structure includes a steel formwork base 1, with an insulation layer 2 on one side of the steel formwork base 1, and an insulating and heat-insulating layer 3, a heating circuit layer 4, and a detachable protective panel 5 sequentially arranged on the other side. The heating circuit layer 4 is electrically connected to the intelligent temperature control unit. Figure 1 The middle arrow indicates the direction of heat transfer from the heating circuit layer 4 into the concrete interior.

[0024] In this embodiment, the steel formwork base 1 is a standardized flat or curved steel plate with a thickness of 4-6mm. It has a grid-shaped reinforcing rib welded to the back and standardized connecting slots or bolt holes on the edges for rapid assembly and locking of multiple formwork panels. The steel formwork base provides structural support for the entire system.

[0025] The insulation layer 2 is made of rigid polyurethane foam, which is tightly attached to the outer surface of the steel formwork substrate 1 through high-pressure spraying or casting. The thickness is 30-50mm, and the thermal conductivity is ≤0.024W / (m·K), forming an efficient external insulation barrier and reducing heat loss.

[0026] In this embodiment, the insulating and heat-insulating layer 3 is a high-temperature resistant silicone coating or mica sheet layer, which is applied to the inner surface of the steel template substrate 1. Its main function is to isolate the heating circuit layer 4 from the steel template substrate 1, so as to ensure electrical safety and long-term thermal stability.

[0027] In this embodiment, the heating circuit layer 4 is bonded to the surface of the insulating and heat-insulating layer 3 through a high-temperature curing process. The heating circuit layer 4 uses graphene-modified polytetrafluoroethylene composite material as a flexible substrate, on which a conductive circuit is formed by printing or etching. Graphene material endows it with excellent electrothermal conversion efficiency (>95%), uniform surface heating characteristics, and good mechanical flexibility and chemical stability. Its layout schematic diagram can be found in [reference needed]. Figure 2 As shown, the circuit employs a serpentine wiring design, divided into four independent zones (A, B, C, and D). Each zone can be controlled independently, achieving uniform temperature distribution and zoned temperature regulation. The positive and negative terminals are used to connect to the intelligent temperature control unit.

[0028] In this embodiment, the protective panel 5 is an anodized aluminum plate or fiberglass reinforced resin plate with a thickness of 2-3mm. It is connected to the steel template base frame by peripheral magnetic strips or quick-release screws, covering and protecting the internal heating circuit layer 4. The panel has a smooth surface, which can serve as a contact surface for concrete, making it easy to demold and clean.

[0029] In this embodiment, the intelligent temperature control unit includes a temperature sensor group, a microprocessor controller, a power module, and a human-machine interface.

[0030] The temperature sensor group includes at least a pre-embedded sensor embedded in the concrete and a sensor attached to the inner surface of the steel formwork substrate 1.

[0031] The microprocessor controller can dynamically adjust the power output to the circuit layer using a PID algorithm based on a preset curing temperature curve and real-time temperature data. See details... Figure 3 As shown, Figure 3 The working principle of the intelligent temperature control unit was demonstrated. A group of temperature sensors collects internal and surface temperature data of the concrete, which, along with parameters set by the user through a human-machine interface, is input into a microprocessor controller. The controller calculates the control input using a PID algorithm, and adjusts the electrical power supplied to the composite heating template via the power output module, forming a closed-loop control to ensure that the concrete curing temperature remains stable within the set range.

[0032] Compared with the prior art, the present invention has the following advantages: High efficiency and energy saving with precise temperature control: The polyurethane insulation layer 2 greatly reduces heat loss (thermal conductivity ≤0.024W / (m·K)), and the graphene heating circuit has a thermal efficiency >95%. The intelligent temperature control unit achieves closed-loop control through a PID algorithm, with a temperature control accuracy of ±1℃, ensuring the quality of concrete curing.

[0033] Integrated and reusable: Insulation, heating, and formwork functions are integrated into a single standard module. The formwork uses a robust steel base and durable materials, and can be reused more than 300 times. The cost per use is only 2.7 yuan / m² (calculated based on an initial investment of 800 yuan / m²), which is more than 85% lower than the traditional method (120 yuan / m²).

[0034] Convenient construction and improved efficiency: The standardized design of the formwork allows for rapid assembly and immediate operation upon power connection, simplifying the tedious processes of covering, wrapping, and monitoring during winter construction. Intelligent temperature control reduces the workload of manual inspection and adjustment, increasing construction efficiency by over 40%.

[0035] Safe and reliable: The multi-layered structure design ensures electrical insulation and fire safety. The heating circuit operates at a safe voltage (DC24V), and the intelligent system has multiple protection functions such as over-temperature, over-current, and short-circuit protection, ensuring safe and reliable operation.

[0036] Significant environmental benefits: The reusable design reduces the use of traditional disposable insulation materials such as cotton quilts and electric blankets, reducing construction waste by more than 90%, which meets the requirements of green construction.

[0037] Wide range of applications: The size and shape can be customized according to the project requirements. It is not only suitable for bridge abutments, piers, cap beams and other structures, but also for winter construction of concrete structures such as tunnel sidewalls, cast-in-place floor slabs and walls.

[0038] Example 2 This invention also provides a construction method for intelligent electric heating and insulation formwork for concrete in winter construction, using the intelligent electric heating and insulation formwork system in Example 1, with the following specific steps: Step 1: Template assembly and sensor installation; Multiple composite insulation templates are assembled into the required large template system using standardized connectors; When tying the reinforcing bars, the water-resistant temperature sensor probe is fixed inside the reinforcing mesh beforehand, and the wire is led out.

[0039] Preferably, temperature sensor probes are pre-embedded at different depths on the inner side of the steel mesh.

[0040] Step 2: System Connection and Preheating; After the template is installed in place, connect the wires of the temperature sensor group to the intelligent temperature control unit, and connect the heating circuit of each template to the output terminal of the temperature control unit in parallel.

[0041] Preferably, before pouring concrete, the formwork preheating program is started to raise the temperature inside the formwork to above 5°C.

[0042] Step 3: Concrete pouring and curing setup; Concrete is poured, and curing parameters are set through the human-machine interface of the intelligent temperature control unit.

[0043] The curing parameters include the target temperature range and the curing period. The target temperature range is designed to be (10~15℃)±2℃, and the curing period is determined according to the concrete grade and is about 3-7 days.

[0044] Step 4: Intelligent closed-loop control; During the curing period, the intelligent temperature control unit compares the actual values ​​of the sensors with the target values ​​in real time, and dynamically adjusts the output power through the PID algorithm to keep the core temperature and surface temperature of the concrete within the set range.

[0045] Step 5: System shutdown and template removal; After curing is completed, the system automatically stops heating. Once the concrete strength reaches the standard, the formwork is removed, the surface of the protective panel 5 is cleaned, and the concrete is transferred to the next construction section for reuse.

[0046] This invention is the first to apply graphene electrothermal technology to the field of winter construction and curing of concrete. The graphene heating circuit has advantages such as high thermal efficiency (>95%), uniform heating, good flexibility, and long life (up to 300 cycles or more), solving the problems of uneven heating and short life of traditional heating wires. The intelligent temperature control unit realizes closed-loop control based on PID algorithm to ensure accurate and stable concrete curing temperature.

[0047] The following uses the winter construction of bridge piers in the Phoenix Yellow River Avenue South Extension Project as an example to illustrate the specific implementation of this invention: The pier column has a cross-sectional dimension of 1.8m × 1.6m and a height of 8m. The composite thermal insulation formwork system of this invention is used for winter construction and maintenance. The specific steps are as follows: Based on the pier dimensions, 24 standard template units (each measuring 1.5m × 1.0m) are assembled into a pier template system and connected by standardized bolts.

[0048] When binding the steel bars of the pier column, temperature sensors were pre-embedded at depths of 50mm, 100mm and 150mm from the inner surface of the formwork, for a total of 12 monitoring points.

[0049] After the template is installed, connect the temperature sensor wires and the template heating circuit to the intelligent temperature control unit. Start preheating 2 hours before pouring to bring the inner surface temperature of the template to 8°C.

[0050] When pouring C40 concrete, the temperature upon placement should be controlled above 10℃. After pouring, set the curing parameters on the intelligent temperature control unit: target temperature 12℃±2℃, curing period 5 days.

[0051] During the curing period, the intelligent temperature control unit automatically adjusts the heating power based on temperature feedback. On day 1, during the rapid heating phase, the heating power is higher; on days 2-4, during the constant temperature curing phase, the power is stable; and on day 5, during the slow cooling phase, the power gradually decreases.

[0052] After curing, once the concrete strength reaches more than 85% of the design value, the formwork is removed. The formwork is then cleaned and transferred to the next pier for reuse.

[0053] Main materials and equipment: By successfully applying this technology during winter construction of the Phoenix Yellow River Avenue South Extension Project, the challenge of curing concrete piers at -10℃ was solved. The concrete developed normally, with no frost damage or cracks, and the quality fully met the design requirements. Compared with traditional insulation methods, it saves approximately 75% in curing costs and shortens the construction period by approximately 20%.

Claims

1. A smart electric heating and insulation formwork system for concrete construction in winter, characterized in that, Includes a composite structure and an intelligent temperature control unit; The composite structure includes a steel template base (1), with a heat insulation layer (2) provided on one side of the steel template base (1), and an insulating and heat-insulating layer (3), a heating circuit layer (4), and a detachable protective panel (5) provided on the other side in sequence. The heating circuit layer (4) is electrically connected to the intelligent temperature control unit.

2. The intelligent electric heating insulation template system according to claim 1, characterized in that, The insulation layer (2) is made of rigid polyurethane foam and is tightly attached to the outer surface of the steel template substrate (1) by high-pressure spraying or casting molding process.

3. The intelligent electric heating insulation template system according to claim 1, characterized in that, The heating circuit layer (4) is bonded to the surface of the insulating and heat-insulating layer (3) by a high-temperature curing process. The heating circuit layer (4) uses graphene-modified polytetrafluoroethylene composite material as a flexible substrate, and a conductive circuit is formed on it by printing or etching processes.

4. The intelligent electric heating insulation template system according to claim 1, characterized in that, The protective panel (5) covers the heating circuit layer (4) and is detachably connected to the steel template base (1). The surface of the protective panel (5) is smooth.

5. The intelligent electric heating insulation template system according to claim 1, characterized in that, The intelligent temperature control unit includes a temperature sensor group, a microprocessor controller, a power module, and a human-machine interface; The temperature sensor group includes at least a pre-embedded sensor embedded in the concrete and a sensor attached to the inner surface of the steel formwork substrate (1). The microprocessor controller can dynamically adjust the power output to the circuit layer using a PID algorithm based on a preset maintenance temperature curve and real-time temperature data.

6. A construction method for intelligent electric heating insulation formwork for concrete in winter construction, characterized in that, The intelligent electric heating insulation template system according to any one of claims 1-5 comprises the following specific steps: Step 1: Template assembly and sensor installation; Multiple composite insulation templates are assembled into the required large template system using standardized connectors; When tying the reinforcing bars, the water-resistant temperature sensor probe is fixed inside the reinforcing mesh beforehand, and the wire is led out. Step 2: System Connection and Preheating; After the template is installed in place, connect each wire of the temperature sensor group to the intelligent temperature control unit, and connect the heating circuit of each template to the output terminal of the temperature control unit in parallel. Step 3: Concrete pouring and curing setup; Pour concrete and set curing parameters through the human-machine interface of the intelligent temperature control unit; Step 4: Intelligent closed-loop control; During the curing period, the intelligent temperature control unit compares the measured values ​​of the sensors with the target values ​​in real time, and dynamically adjusts the output power through the PID algorithm to keep the core temperature and surface temperature of the concrete within the set range. Step 5: System shutdown and template removal; After the curing is completed, the system will automatically stop heating. Once the concrete strength reaches the standard, the formwork will be removed, the surface of the protective panel (5) will be cleaned, and the concrete will be transferred to the next construction section for reuse.

7. The construction method according to claim 6, characterized in that, In step one, temperature sensor probes are pre-embedded at different depths on the inner side of the steel mesh.

8. The construction method according to claim 6, characterized in that, In step two, before pouring concrete, the formwork preheating program is started to raise the temperature inside the formwork to above 5°C.

9. The construction method according to claim 6, characterized in that, The maintenance parameters in step three include the target temperature range and the maintenance cycle.

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