Green construction method for fabricated prefabricated shear wall grouting sleeve in winter low-temperature environment

Abstract

The invention relates to a green construction method for a prefabricated shear wall grouting sleeve in a winter low-temperature environment. The green construction method comprises the following steps: step A, preparing a low-temperature modified grouting material; step B, construction environment control; step C, sleeve grouting process; and D, maintenance and form removal are conducted. The low-temperature modified grouting material has the beneficial effects that by using the low-temperature modified grouting material, it is ensured that the grouting material can still keep good fluidity and strength increase in the environment of-10 DEG C, specifically, the compressive strength of the grouting material in the environment of-10 DEG C within 3 days can reach 45 MPa or above, and the compressive strength in the environment of-10 DEG C within 28 days can reach 88 MPa or above, so that the performance of the grouting material in the low-temperature environment is remarkably improved, and the service life of the grouting material is prolonged. The grouting quality is ensured, and the problems of uncompacted grouting and insufficient strength caused by low temperature are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, and in particular to a green construction method for an assembled prefabricated shear wall grouting sleeve in a low-temperature environment in winter. Background Art

[0002] Prefabricated shear wall structures have been widely used in recent years as an efficient and environmentally friendly construction method. One of its core connection technologies is the grouting sleeve connection, which achieves a reliable connection between prefabricated components by embedding sleeves and injecting grouting material into the prefabricated components.

[0003] After searching, the Chinese patent number CN116733229A discloses that the invention addresses the problem that the external ambient temperature cannot meet the requirements for grouting material construction in a low-temperature environment. It provides a method for constructing a prefabricated shear wall grouting sleeve in a low-temperature winter environment. In order to meet the space requirements for heat storage and insulation, the prefabricated structure adopts a "post-grouting method" installation process. That is, after the wall is hoisted and fixed, the composite floor is installed and the top slab concrete is poured. After that, it is covered with insulation material for insulation and sealing. The door and window openings are sealed with insulation material to form an enclosed space. Heating is carried out by heating equipment such as a heater and real-time temperature data is read through pre-buried temperature measuring wires and indoor thermometers. The sleeve grouting operation is carried out when the grouting operation temperature in the sleeve reaches above -5°C, meeting the use requirements of low-temperature grouting materials and solving the problem that grouting operations cannot be carried out at low temperatures in winter. This method is used for winter construction projects of vertical wall column connections in prefabricated buildings.

[0004] The above-mentioned green construction method of shear wall grouting sleeve in low temperature environment in winter has the following shortcomings: in low temperature environment, the fluidity and strength development of ordinary grouting materials are inhibited, and it is difficult to ensure the quality of grouting, and the grouting material has poor fluidity at low temperature, resulting in loose grouting, affecting the overall performance and durability of the structure; in addition, traditional insulation methods such as greenhouse method and steam curing are complicated to construct and have high energy consumption, which does not conform to the concept of green construction. These methods require a large amount of insulation materials and energy consumption, which increases construction costs and environmental burden. Based on this, the present invention designs a green construction method of assembled prefabricated shear wall grouting sleeve in low temperature environment in winter to solve the above problems. Summary of the Invention

[0005] (1) Technical issues to be resolved In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a green construction method for assembled prefabricated shear wall grouting sleeves in low-temperature environments in winter, which solves the technical problem of limited performance.

[0006] (2) Technical solution In order to achieve the above objectives, the main technical solutions adopted by the present invention include: A green construction method for prefabricated shear wall grouting sleeves in a low-temperature environment in winter, comprising the following steps: Step A, preparation of low-temperature modified grouting material: using a composite cement-based grouting material, whose components are 45-55% of silicate cement, 20-30% of sulfoaluminate cement, 3-5% of nano-silica, 0.5-1.2% of polycarboxylic acid-based high-efficiency water reducer, 2-5% of early strength agent, 3-6% of antifreeze agent, and the balance is graded quartz sand. The water-cement ratio is 0.26-0.30, the initial fluidity is ≥320 mm, the 3d compressive strength at -10°C is ≥45 MPa, and the 28d compressive strength is ≥88 MPa.

[0007] Step B, construction environment control: After the prefabricated wall is hoisted, the work area is enclosed with a double-layer flame-retardant tarpaulin + 50mm rock wool insulation board to form an insulated space. The temperature field distribution in the space is monitored in real time using an infrared thermal imager to ensure that the temperature in the sleeve area is ≥-4°C and the gradient is ≤16°C / h. A variable frequency air source heat pump and carbon fiber infrared radiation panels are used for composite heating to maintain the temperature of the enclosed space at 4-10°C.

[0008] Step C, sleeve grouting process: Before grouting, a pre-buried Pt100 temperature sensor is used to monitor the temperature of the inner cavity of the sleeve to ensure that the sleeve temperature is ≥3°C during grouting. A screw grouting machine is used for grouting, and the grouting flow rate is controlled at 0.8-1.5L / min. The grouting material outlet temperature is ≥15°C. The fullness of the single sleeve grouting is verified by an ultrasonic detector, and the wave velocity difference is required to be ≤4%.

[0009] Step D, curing and demolding: Immediately after grouting, cover with nano-aerogel composite insulation felt and maintain the ambient temperature ≥ 4°C for 72 h. Use MATLAB numerical simulation software to analyze the temperature stress field and control the cooling rate to ≤ 10°C / h. Remove the insulation measures after the grouting body reaches 92% of the design strength.

[0010] Preferably, in step A, the mass ratio of sulphoaluminate cement to silicate cement is 1:2, the molar ratio of calcium nitrate to calcium formate in the early strength agent is 1:1.2, and the mass ratio of sodium nitrite to urea in the antifreeze agent is 1:0.8.

[0011] Through the above technical solutions, it can be seen that: the performance optimization and action mechanism of the low-temperature modified grouting material, in a low-temperature environment, the fluidity and strength development of the grouting material are significantly inhibited. The present invention significantly improves the low-temperature performance of the grouting material through the synergistic effect of the composite cement-based system and nano-silica. The rapid hydration characteristics of sulphoaluminate cement can still maintain a high reaction activity at low temperatures, and nano-silica refines the pore structure through the filling effect and volcanic ash effect, reducing the porosity to 8-12%, thereby improving the density and frost resistance of the grouting material. In addition, the combined use of polycarboxylic acid-based high-efficiency water reducers and antifreeze agents further improves the fluidity and low-temperature adaptability of the grouting material, ensuring that the 3d compressive strength is ≥45MPa and the 28d compressive strength is ≥88MPa at -10°C.

[0012] Preferably, the thermal calculation of the enclosed space in step B is simulated by EnergyPlus software, requiring the comprehensive heat transfer coefficient of the enclosure structure K≤1.2W / (m 2 ·K), the thickness of the additional insulation layer at the thermal bridge location shall not be less than 1.6 times the thickness of the main insulation layer.

[0013] Through the above technical solutions, it can be seen that: the refinement of construction environment control and thermal optimization, and the temperature control of the construction environment are the key to ensuring the quality of grouting. The present invention adopts a double-layer flame-retardant tarpaulin combined with a 50mm rock wool insulation board to form a closed insulation space, and uses an infrared thermal imager to monitor the temperature field distribution in real time to ensure that the temperature of the sleeve area is ≥-4°C and the temperature gradient is ≤16°C / h. The composite heating system of the variable frequency air source heat pump and the carbon fiber infrared radiation panel can efficiently and evenly maintain the temperature of the enclosed space within the range of 4-10°C. The radiation efficiency of the carbon fiber infrared radiation panel is ≥85%, the wavelength range is 2-10μm, it can respond quickly and heat evenly, and reduce heat loss. The thermal performance of the enclosure structure is simulated by EnergyPlus software to ensure that the comprehensive heat transfer coefficient K is ≤1.2W / (m 2 ·K), the thickness of the additional insulation layer at the thermal bridge location shall not be less than 1.6 times that of the main body insulation layer, thereby effectively avoiding the local thermal bridge effect.

[0014] Preferably, in step C, the ratio of the sleeve inner cavity diameter to the steel bar gap is controlled at 1.25-1.45, and the grouting pressure P and the sleeve length L satisfy the relationship: P=0.2L+0.6.

[0015] Through the above technical solutions, it can be seen that the core of the grouting process for precise control and quality assurance of the sleeve grouting process is to ensure the density of the grouting material and the temperature uniformity of the inner cavity of the sleeve. The present invention adopts a pre-buried Pt100 temperature sensor to monitor the temperature of the inner cavity of the sleeve in real time to ensure that the sleeve temperature is ≥3°C during grouting. The grouting pressure fluctuation range of the screw grouting machine is ≤±0.1MPa, and the grouting flow rate is controlled at 0.8-1.5L / min to ensure that the grouting material is evenly filled in the sleeve. The outlet temperature of the grouting material is ≥15°C, and the fullness of the single sleeve grouting is verified by an ultrasonic detector, requiring a wave velocity difference of ≤4%. In addition, X-ray tomography (CT) technology is used to verify the density of the grouting and ensure that the porosity is ≤1.5%, thereby ensuring the overall performance of the grouting body.

[0016] Preferably, in the curing stage in step D, a wireless temperature and humidity recorder is used to collect data every 30 minutes, and the equivalent age is required to satisfy ∑(T+10)Δt≥800°C·d.

[0017] Through the above technical solutions, it can be seen that: temperature stress control and strength development prediction during the curing stage, after grouting is completed, temperature stress control during the curing stage is the key to avoiding cracking of the grouting body. The present invention uses nano-aerogel composite insulation felt to cover the grouting body, which has a thermal conductivity of ≤0.018W / (m·K) and a tensile strength of ≥80kPa, and can effectively maintain an ambient temperature of ≥4°C for 72 hours. The temperature stress field is numerically simulated by MATLAB and ANSYS software, and the cooling rate is controlled to be ≤10°C / h to ensure that the maximum temperature stress is ≤2.5MPa. At the same time, a wireless temperature and humidity recorder is used to collect data every 30 minutes, and the Weibull distribution model is combined to predict strength development. The equivalent age is required to meet ∑(T+10)Δt≥800°C·d, so as to accurately control the curing cycle and ensure that the insulation measures are removed after the grouting body reaches 92% of the design strength.

[0018] Preferably, the specific surface area of ​​the nano-silicon dioxide in step A is ≥200m 2 / g, particle size distribution D50≤50nm, the porosity of the grouting material is reduced to 8-12% after addition, and the hydration heat peak is advanced to 4-6h at -10℃ environment, and the peak temperature is ≥35℃.

[0019] Preferably, the water vapor permeability of the double-layer flame retardant tarpaulin in step B is ≤0.5g / (m 2 h), the compressive strength of the rock wool insulation board is ≥40kPa, the temperature uniformity in the space is required to be ≤±2℃, and the energy efficiency ratio of the heat pump system is ≥3.5.

[0020] Preferably, in step C, the grouting pressure fluctuation range of the grouting machine is ≤±0.1 MPa, the water bleeding rate of the grouting material is ≤0.5%, and the grouting density of the sleeve inner cavity is verified by X-ray tomography, requiring a porosity of ≤1.5%.

[0021] Preferably, the thermal conductivity of the nano-aerogel composite insulation felt in step D is ≤0.018W / (m·K), and the tensile strength is ≥80kPa. During the curing period, the temperature stress field simulation is performed using ANSYS software, and the maximum temperature stress is required to be ≤2.5MPa to avoid cracking of the grouting body.

[0022] Preferably, the carbon fiber infrared radiation plate in step B has a radiation efficiency of ≥85%, a wavelength range of 2-10 μm, a heating uniformity of ≥90%, and a thermal response time of ≤10 min.

[0023] (3) Beneficial effects 1. The present invention ensures that the grouting material can maintain good fluidity and strength growth in a -10°C environment by using a low-temperature modified grouting material. Specifically, the compressive strength of the grouting material can reach more than 45 MPa in 3 days and more than 88 MPa in 28 days in a -10°C environment. This significantly improves the performance of the grouting material in a low-temperature environment, ensures the grouting quality, and avoids the problems of loose grouting and insufficient strength caused by low temperature.

[0024] 2. This invention uses a double-layer flame-retardant tarpaulin and 50mm-thick rock wool insulation panels to enclose the work area, creating an insulated space. An infrared thermal imager monitors the temperature distribution in the space in real time, ensuring that the sleeve area temperature is ≥ -4°C and the gradient is ≤ 16°C / h. A composite heating system, combining a variable-frequency air-source heat pump and carbon fiber infrared radiation panels, automatically adjusts the temperature based on real-time monitoring data, maintaining the temperature within the enclosed space between 4°C and 10°C. This insulation measure is simple, energy-efficient, and consistent with green construction principles, significantly reducing construction costs and environmental impact.

[0025] 3. The present invention ensures the stability and uniformity of the grouting process by precisely controlling the temperature of the inner cavity of the sleeve before grouting and the temperature of the grouting material out of the machine. The screw grouting machine performs grouting at a flow rate of 0.8-1.5L / min, ensuring uniform filling of the grouting material. The use of an ultrasonic detector verifies the grouting fullness of a single sleeve, and the wave velocity difference is controlled within 4%, ensuring the grouting quality. These measures significantly improve construction efficiency and shorten construction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart for preparing the low-temperature modified grouting material of the present invention; Figure 2 This is a flow chart of the construction environment control of the present invention; Figure 3 This is a flow chart of the sleeve grouting process of the present invention; Figure 4 This is a flow chart for maintenance and demoulding. DETAILED DESCRIPTION

[0027] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below with reference to the accompanying drawings and through specific embodiments. Figure 1 The orientation is referenced.

[0028] The technical problem of limited performance raised in the embodiments of the present invention is solved by using a low-temperature modified grouting material. The present invention ensures that the grouting material can still maintain good fluidity and strength growth in an environment of -10°C. Specifically, the compressive strength of the grouting material can reach more than 45 MPa in a 3-day environment at -10°C, and the compressive strength can reach more than 88 MPa in a 28-day environment. This significantly improves the performance of the grouting material in a low-temperature environment, ensures the grouting quality, and avoids the problems of loose grouting and insufficient strength due to low temperature.

[0029] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Instead, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0030] Example 1; See also Figures 1-4, a green construction method for prefabricated shear wall grouting sleeve in low temperature environment in winter, comprising the following steps: Step A, preparation of low temperature modified grouting material: using composite cement-based grouting material, the components of which are 45-55% silicate cement, 20-30% sulphoaluminate cement, 3-5% nano-silicon dioxide, 0.5-1.2% polycarboxylic acid series high-efficiency water reducer, 2-5% early strength agent, 3-6% antifreeze agent, and the balance is graded quartz sand, the water-cement ratio is 0.26-0.30, the initial fluidity is ≥320mm, the 3d compressive strength is ≥45MPa at -10℃, and the 28d compressive strength is ≥88MPa; Step B, construction environment control: after the prefabricated wall is hoisted, the working area is enclosed with double-layer flame-retardant tarpaulin + 50mm rock wool insulation board to form an insulation space, and the temperature field distribution of the space is monitored in real time by an infrared thermal imager to ensure the sleeve The regional temperature is ≥-4℃ and the gradient is ≤16℃ / h. A variable frequency air source heat pump and carbon fiber infrared radiation panel are used for composite heating to maintain the temperature of the enclosed space at 4-10℃; Step C, sleeve grouting process: Before grouting, a pre-buried Pt100 temperature sensor is used to monitor the temperature of the sleeve cavity to ensure that the sleeve temperature is ≥3℃ during grouting. A screw grouting machine is used for grouting, and the grouting flow rate is controlled at 0.8-1.5L / min. The grouting material outlet temperature is ≥15℃. The fullness of the single sleeve grouting is verified by an ultrasonic detector, and the wave velocity difference is required to be ≤4%; Step D, curing and demolding: After the grouting is completed, the nano aerogel composite insulation felt is immediately covered, and the ambient temperature is maintained at ≥4℃ for 72h. The temperature stress field is analyzed using MATLAB numerical simulation software, and the cooling rate is controlled to be ≤10℃ / h. The insulation measures are removed after the grouting body reaches 92% of the design strength.

[0031] The working principle of the embodiment of the present invention is: by accurately proportioning and mixing a variety of materials, a composite cement-based grouting material suitable for low-temperature environments is prepared. The synergistic effect of silicate cement and sulphoaluminate cement provides basic strength and durability, while the addition of nano-silica significantly improves the density and early strength development of the grouting material. The polycarboxylic acid-based high-efficiency water reducer ensures the high fluidity of the grouting material at a low water-cement ratio, while the addition of early strength agent and antifreeze agent further improves the performance of the grouting material under low temperature conditions. Through this optimized material combination, the grouting material can still maintain good fluidity and strength growth in an environment of -10°C, ensuring the reliability of construction and the safety of the structure.

[0032] After the prefabricated wall was hoisted, the work area was enclosed with a double-layer flame-retardant tarp and 50mm-thick rock wool insulation panels to create an insulated space. Infrared thermal imaging cameras monitored the temperature distribution in the space in real time, ensuring that the temperature in the sleeve area remained ≥ -4°C with a gradient ≤ 16°C / hour. A hybrid heating system combining a variable-frequency air-source heat pump and carbon fiber infrared radiant panels automatically adjusted the temperature based on real-time monitoring data, maintaining the enclosed space between 4°C and 10°C, providing ideal environmental conditions for grouting operations.

[0033] Before grouting, a pre-embedded Pt100 temperature sensor monitors the temperature of the sleeve cavity in real time, ensuring it remains above 3°C during grouting. A screw grouting machine injects grout at a flow rate of 0.8-1.5 L / min, ensuring uniform grouting. The grouting material's exit temperature is controlled above 15°C, further ensuring fluidity. An ultrasonic detector verifies the grouting fullness of each sleeve, keeping the wave velocity difference within 4% to ensure grouting quality.

[0034] Immediately after grouting, the nano-aerogel composite insulation felt was applied to maintain the ambient temperature above 4°C for 72 hours. MATLAB numerical simulation software was used to analyze the temperature stress field and precisely control the cooling rate to within 10°C / hour, preventing cracking of the grouting caused by rapid temperature changes. When the grouting reached 92% of its design strength, the insulation was removed.

[0035] Example 2; See also Figures 1-4 In step A, the mass ratio of sulphoaluminate cement to silicate cement is 1:2, the molar ratio of calcium nitrate to calcium formate in the early strength agent is 1:1.2, and the mass ratio of sodium nitrite to urea in the antifreeze agent is 1:0.8. The thermal calculation of the enclosed space in step B is simulated by EnergyPlus software, requiring the comprehensive heat transfer coefficient of the enclosure structure K≤1.2W / (m 2 ·K), and the thickness of the additional insulation layer at the thermal bridge site must be no less than 1.6 times the thickness of the main insulation layer. In step C, the ratio of the sleeve inner diameter to the rebar gap must be controlled between 1.25 and 1.45, and the grouting pressure P and sleeve length L must satisfy the relationship: P = 0.2L + 0.6. During the curing phase in step D, a wireless temperature and humidity recorder should be used to collect data every 30 minutes, with the equivalent age requirement of ∑(T+10)Δt ≥ 800℃·d.

[0036] The specific surface area of ​​nano-silicon dioxide in step A is ≥200m 2 / g, particle size distribution D50≤50nm, the porosity of the grouting material is reduced to 8-12% after addition, and the hydration heat peak is advanced to 4-6h at -10℃ environment, and the peak temperature is ≥35℃.

[0037] The working principle of the embodiment of the present invention is as follows: the mass ratio of sulphoaluminate cement to silicate cement is 1:2, the molar ratio of calcium nitrate to calcium formate in the early strength agent is 1:1.2, and the mass ratio of sodium nitrite to urea in the antifreeze agent is 1:0.8. These precise proportions further optimize the performance of the grouting material, ensuring its fluidity and strength development in low temperature environments. In addition, the specific surface area of ​​nano-silica is ≥200m 2 / g, particle size distribution D50 ≤ 50nm, the porosity of the grouting material is reduced to 8-12% after incorporation, and the hydration heat peak is advanced to 4-6 hours at -10°C, with a peak temperature ≥ 35°C. These characteristics significantly improve the early strength and durability of the grouting material.

[0038] Example 3; See also Figures 1-4 The moisture permeability of the double-layer flame retardant tarpaulin in step B is ≤0.5g / (m 2 ·h), the compressive strength of the rock wool insulation board is ≥40kPa, the temperature uniformity in the space is required to be ≤±2℃, and the energy efficiency ratio of the heat pump system is ≥3.5. In step C, the grouting pressure fluctuation range of the grouting machine is ≤±0.1MPa, the water bleeding rate of the grouting material is ≤0.5%, the grouting density of the sleeve cavity is verified by X-ray tomography, and the porosity is required to be ≤1.5%. In step D, the thermal conductivity of the nano-aerogel composite insulation felt is ≤0.018W / (m·K), the tensile strength is ≥80kPa, and the temperature stress field simulation is performed using ANSYS software during the curing period. The maximum temperature stress is required to be ≤2.5MPa to avoid cracking of the grouting body.

[0039] The carbon fiber infrared radiation plate in step B has a radiation efficiency of ≥85%, a wavelength range of 2-10 μm, a heating uniformity of ≥90%, and a thermal response time of ≤10 min.

[0040] The working principle of the embodiment of the present invention is: the moisture permeability of the double-layer flame retardant tarpaulin is ≤0.5g / (m 2 h), the compressive strength of the rock wool insulation board must be ≥40kPa, the temperature uniformity within the space must be ≤±2°C, and the heat pump system energy efficiency ratio must be ≥3.5. These parameters ensure the stability and uniformity of the insulation space and further improve the controllability of the construction environment. The carbon fiber infrared radiation panel has a radiation efficiency of ≥85%, a wavelength range of 2-10μm, a heating uniformity of ≥90%, and a thermal response time of ≤10 minutes. These characteristics ensure the efficiency and uniformity of the heating system.

[0041] The grouting pressure fluctuation range of the grouting machine is ≤±0.1MPa, the water bleeding rate of the grouting material is ≤0.5%, and the grouting density of the sleeve cavity is verified by X-ray tomography, with a porosity requirement of ≤1.5%. These precise control measures ensure the stability of the grouting process and the reliability of the grouting quality.

[0042] The thermal conductivity of the nano-aerogel composite insulation felt is ≤0.018W / (m·K) and the tensile strength is ≥80kPa. During the curing period, ANSYS software was used to simulate the temperature stress field, requiring the maximum temperature stress to be ≤2.5MPa to prevent cracking of the grouting. These measures ensure the stability and ultimate performance of the grouting during the curing period.

[0043] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0044] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0045] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0046] In the description of this specification, the terms "one embodiment", "some embodiments", "embodiments", "examples", "specific examples" or "some examples" refer to the specific features, structures, materials or characteristics described in conjunction with the embodiment or example and included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0047] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A green construction method for prefabricated shear wall grouting sleeve in low temperature environment in winter, characterized in that: The following steps are involved: Step A, preparation of low-temperature modified grouting material: using a composite cement-based grouting material, the components of which are 45-55% silicate cement, 20-30% sulfoaluminate cement, 3-5% nano-silica, 0.5-1.2% polycarboxylic acid-based high-efficiency water reducer, 2-5% early strength agent, 3-6% antifreeze agent, and the balance is graded quartz sand, the water-cement ratio is 0.26-0.30, the initial fluidity is ≥320 mm, the 3-day compressive strength at -10°C is ≥45 MPa, and the 28-day compressive strength is ≥88 MPa; Step B, construction environment control: After the prefabricated wall is hoisted, the work area is enclosed with a double-layer flame-retardant tarpaulin and 50mm rock wool insulation board to form an insulated space. The temperature field distribution in the space is monitored in real time using an infrared thermal imager to ensure that the temperature in the sleeve area is ≥ -4°C and the gradient is ≤ 16°C / h. A variable frequency air source heat pump and carbon fiber infrared radiation panels are used for combined heating to maintain the temperature of the enclosed space at 4-10°C. Step C, sleeve grouting process: Before grouting, a pre-buried Pt100 temperature sensor is used to monitor the temperature of the sleeve cavity to ensure that the sleeve temperature is ≥3°C during grouting. A screw grouting machine is used for grouting, and the grouting flow rate is controlled at 0.8-1.5L / min. The grouting material outlet temperature is ≥15°C. The fullness of the single sleeve grouting is verified by an ultrasonic detector, and the wave velocity difference is required to be ≤4%; Step D, curing and demolding: Immediately after grouting, cover with nano-aerogel composite insulation felt and maintain the ambient temperature ≥ 4°C for 72 h. Use MATLAB numerical simulation software to analyze the temperature stress field and control the cooling rate to ≤ 10°C / h. Remove the insulation measures after the grouting body reaches 92% of the design strength.

2. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: In step A, the mass ratio of sulphoaluminate cement to silicate cement is 1:2, the molar ratio of calcium nitrate to calcium formate in the early strength agent is 1:1.2, and the mass ratio of sodium nitrite to urea in the antifreeze agent is 1:0.

8.

3. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: The thermal calculation of the enclosed space in step B is simulated by EnergyPlus software, and the comprehensive heat transfer coefficient of the enclosure structure is required to be K≤1.2W / (m 2 ·K), the thickness of the additional insulation layer at the thermal bridge location shall not be less than 1.6 times the thickness of the main insulation layer.

4. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: In step C, the ratio of the sleeve inner cavity diameter to the steel bar gap is controlled at 1.25-1.45, and the grouting pressure P and the sleeve length L satisfy the relationship: P=0.2L+0.

6.

5. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: During the curing phase in step D, a wireless temperature and humidity recorder is used to collect data every 30 minutes, and the equivalent age is required to satisfy ∑(T+10)Δt≥800°C·d.

6. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: The specific surface area of ​​the nano-silicon dioxide in step A is ≥200m 2 / g, particle size distribution D50≤50nm, the porosity of the grouting material is reduced to 8-12% after addition, and the hydration heat peak is advanced to 4-6h at -10℃ environment, and the peak temperature is ≥35℃.

7. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: The moisture permeability of the double-layer flame-retardant tarpaulin in step B is ≤0.5g / (m 2 h), the compressive strength of the rock wool insulation board is ≥40kPa, the temperature uniformity in the space is required to be ≤±2℃, and the energy efficiency ratio of the heat pump system is ≥3.

5.

8. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: In the step C, the grouting pressure fluctuation range of the grouting machine is ≤±0.1MPa, the water bleeding rate of the grouting material is ≤0.5%, and the grouting density of the sleeve cavity is verified by X-ray tomography, and the porosity is required to be ≤1.5%.

9. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: The thermal conductivity of the nano-aerogel composite insulation felt in step D is ≤0.018 W / (m·K), and the tensile strength is ≥80 kPa. During the curing period, the temperature stress field is simulated using ANSYS software, and the maximum temperature stress is required to be ≤2.5 MPa to avoid cracking of the grouting body.

10. The green construction method for prefabricated shear wall grouting sleeve in winter low-temperature environment according to claim 1 is characterized by: The carbon fiber infrared radiation plate in step B has a radiation efficiency of ≥85%, a wavelength range of 2-10 μm, a heating uniformity of ≥90%, and a thermal response time of ≤10 min.

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