Fabricated foam concrete pipeline thermal insulation structure and preparation method thereof

Abstract

The invention relates to the technical field of pipeline heat preservation, and discloses an assembly type foam concrete pipeline heat preservation structure which comprises at least two assembly type pipeline sections, each assembly type pipeline section comprises prefabricated heat preservation units which are symmetrically spliced, the prefabricated heat preservation units are spliced through a stepped lap joint structure, an elastic buffer layer is arranged on the lap joint face, and the prefabricated heat preservation units are arranged on the elastic buffer layers. According to the thermal insulation structure, the foam concrete thermal insulation units doped with basalt fibers are modularized and batched, and are fixed in a stepped lap joint mode and a stainless steel hoop with a rubber pad, so that the thermal conductivity coefficient of the thermal insulation structure is remarkably reduced, and the thermal insulation performance is improved; by the adoption of the assembly type heat preservation structure, frost heaving and cracking of the pipeline caused by soil freezing and thawing circulation due to shallow burying of the pipeline can be reduced, the engineering maintenance cost is reduced, the construction time is long, and remarkable economic benefits and environmental benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline insulation, and in particular to an assembled foam concrete pipeline insulation structure and a preparation method thereof. Background Art

[0002] In some large-diameter water pipeline projects in cold and arid regions, shallow-buried pipelines are often used to adapt to complex mountainous terrain and reduce construction difficulties. However, this approach faces significant challenges. Shallow-buried pipelines are typically buried above the permafrost line. When the soil frost heaves, the heave force squeezes the pipeline, and the temperature difference between the top and bottom of the pipeline causes localized uplift or bending deformation. Long-term accumulation can lead to fatigue fracture. When the soil thaws and settles, the higher soil temperature beneath the pipeline causes it to settle faster than the surrounding soil, creating a suspended section and exacerbating pipeline stress. Furthermore, the interaction between fluctuating water temperatures within the pipeline and the extremely low external temperatures induces fatigue stress in the pipe wall due to thermal expansion and contraction, accelerating pipeline aging and cracking. However, existing insulation materials (such as polyurethane or conventional foam concrete) are weak in strength and freeze-thaw resistance, making them incapable of withstanding frost heave deformation and thermal stress shocks. This can lead to pipeline leakage or structural failure, seriously threatening water transmission safety and the life of the project.

[0003] Current pipeline insulation technology has significant drawbacks: organic materials (such as polyurethane) are flammable and prone to aging, resulting in a short lifespan under freeze-thaw cycles; cast-in-place foam concrete has poor frost resistance (strength loss ≥30% after 25 freeze-thaw cycles), and low-temperature construction is limited on-site; and conventional prefabricated insulation structures lack insulation at joints, increasing heat flux and causing significant thermal bridging. While existing patented technologies (such as CN218063967U) propose prefabricated modular designs, metal hinges are susceptible to corrosion in salt spray environments and rely on hinge bolts for shear resistance, making them prone to failure.

[0004] Therefore, in response to the special needs of shallow buried water pipelines in cold regions, there is an urgent need for a new type of pipeline insulation project that can effectively deal with the heat loss and frost heave damage of shallow buried pipelines in the freeze-thaw environment of cold and arid areas, so as to improve construction efficiency, increase overall stability, extend service life, and reduce maintenance costs. Summary of the Invention

[0005] The object of the present invention is to provide an assembled foam concrete pipe insulation structure to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: an assembled foam concrete pipe insulation structure, comprising: At least two prefabricated pipe sections, each comprising symmetrically joined prefabricated insulation units, each of which is joined by a stepped overlap structure, each having an elastic buffer layer on its overlap surface, and each of which is formed from a foamed concrete matrix comprising cement, a foaming agent, basalt fiber, calcined coal gangue, and silty clay; The inner wall of the prefabricated insulation unit is sequentially covered with a graphite lubricating layer and an anti-corrosion and wear-resistant layer, and the outer wall is sequentially covered with a glass fiber mesh reinforcement layer and a waterproof and antifreeze layer; A stainless steel clamp is coated on the outside of the overlapped portion of the prefabricated thermal insulation unit, and a thermal insulation rubber gasket is provided between the stainless steel clamp and the prefabricated thermal insulation unit; A stainless steel flexible locking belt is embedded in a reserved groove on the outer wall of the prefabricated thermal insulation unit through a nylon insulation sleeve bolt, and is used to connect adjacent prefabricated pipe sections; The joints between adjacent assembled pipeline sections are filled with nano-aerogel felt and covered with HDPE waterproof membrane.

[0007] According to the above technical solution, the friction coefficient of the graphite lubricating layer is ≤0.1, and the allowed axial sliding displacement of the pipeline is ≤5mm; The anti-corrosion and wear-resistant layer is an epoxy resin coating or a polyurethane elastomer layer with a thickness of 0.1-0.5 mm; The fiberglass mesh reinforcement layer has a mesh density of 4-8 meshes / inch; The waterproof and antifreeze layer is a HDPE film or a sprayed polyurea layer, and the thickness of the HDPE film is 1.0-1.5 mm.

[0008] According to the above technical solution, the surface of the stainless steel clamp is coated with a ceramic coating, the coating composition includes Al2O360-70wt%, SiO220-30wt%, and the thickness is 30-80μm.

[0009] According to the above technical solution, the step height of the stepped overlapping structure is 10-25 mm, the overlapping length is ≥50 mm, and the step inclination angle is 30°-45°.

[0010] According to the above technical solution, the width of the stainless steel flexible locking belt is 80-100 mm, the thickness is 1.5-2.0 mm, and the surface is coated with a ceramic coating. The coating composition includes Al2O3 60-70 wt%, SiO2 20-30 wt%, and the thickness is 30-80 μm.

[0011] According to the above technical solution, the elastic buffer layer is a closed-cell rubber or silicone rubber gasket.

[0012] A method for preparing an assembled foam concrete pipe insulation structure comprises the following steps: S1, Preparation of prefabricated insulation units S11, raw material ratio: mix 20-30 parts of calcined coal gangue, 10-20 parts of silty clay, 0.5-2.5 parts of basalt fiber and 50-55 parts of cement, add 3-6 parts of polymer composite cement foaming agent, and the water-binder ratio is 0.4-0.55; S12, mixing and foaming: dry mixing for 3 minutes, adding water and wet mixing for 5 minutes, and injecting into the foaming machine to generate foamed concrete slurry; S13, mold forming: pouring the slurry into a steel mold with a pre-prepared anti-corrosion layer on the inner wall, and vibrating and compacting it; S14, steam curing: curing for 28 days at a constant temperature and relative humidity >95% to form a prefabricated insulation unit with an absolute dry density of 750-850 kg / m³ and a compressive strength ≥2.0 MPa; S2, processing of stepped mortise and tenon joint structures S21, mortise and tenon forming: Process stepped mortise and tenon joints at both ends of the prefabricated insulation unit, with a step height of 10-25mm, an inclination angle of 30°-45°, and an overlap length of ≥50mm; S22, buffer layer installation: embed closed-cell rubber or silicone rubber pads on the mortise and tenon contact surfaces to absorb frost heave displacement energy and block thermal bridge transmission; S23, lock slot reservation: mill a lock belt installation slot with a width of 85mm and a depth of 10mm along the outer wall of the prefabricated insulation unit; S3, stainless steel flexible locking system assembly S31, locking belt fixation: insert the stainless steel flexible locking belt into the reserved groove. The stainless steel locking belt has a thickness of 1.5-2.0mm and a width of 80-100mm. Insert the nylon insulation sleeve bolt. S32, preload control: applied torque 18N·m, axial displacement allowed ±5mm, and a flexible locking system to compensate for thermal expansion and contraction of the pipe; S4, Joint thermal bridge blocking and sealing S41, aerogel filling: fill the joints between adjacent units with nano-aerogel felt to block heat flow transfer; S42, HDPE film coating: using 1.0-1.5mm thick HDPE waterproof film for hot melt welding; S43, external wall spraying: The external wall of the entire pipeline is sprayed with polyurea elastomer with a thickness of 2.5mm to enhance the waterproof and anti-freeze performance.

[0013] According to the above technical solution, in step S3, after the stainless steel flexible locking belt is installed, it is surface treated by spraying an Al2O3-SiO2 ceramic coating with a thickness of 30-80 μm to improve corrosion resistance.

[0014] According to the above technical solution, in step S41, the nano aerogel felt has a thickness of 10-20 mm and a thermal conductivity of ≤0.018 W / (m·K).

[0015] According to the above technical solution, in step S42, the HDPE waterproof membrane is welded at a temperature of 200°C, covering the seam with a weld width of 25 mm to prevent moisture intrusion.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) Improve thermal insulation performance: Foam concrete has low density, high porosity and good thermal insulation performance, which can reduce the damage to pipelines caused by soil freeze-thaw cycles.

[0017] (2) Enhanced mechanical properties: The addition of basalt fiber can effectively improve the ability of foam concrete to resist freeze-thaw and enhance its overall durability and stability.

[0018] (3) Strong structural stability: The stepped mortise and tenon structure can resist frost heave shear force, and the stainless steel locking belt allows ±5mm axial displacement, provides flexible displacement compensation, and reserves space for thermal expansion and contraction of the insulation unit.

[0019] (4) Save material costs: Use calcined coal gangue, an industrial waste material, to replace more than 30% of cement as filler, reducing the consumption of traditional materials, lowering project costs, and improving resource utilization, meeting the requirements of green building materials.

[0020] (5) Efficient and convenient construction: Factory-prefabricated units are combined with mechanical lifting, which greatly shortens the construction period and reduces construction costs compared to ordinary foam concrete or deep-buried pipeline solutions.

[0021] (6) Adapt to cold areas: It is specially designed for shallow buried pipeline projects in cold areas, taking into account multiple functions such as insulation and waterproofing to improve the durability of water supply projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a three-dimensional schematic diagram of the present invention; Figure 2 is a schematic cross-sectional view of the prefabricated thermal insulation unit of the present invention; Figure 3 is a side schematic view of the present invention; Figure 4 It is a schematic flow chart of the preparation method of the present invention; Figure 5 is a schematic diagram of data parameters according to an embodiment of the present invention; In the figure: 1- prefabricated insulation unit, 101- foam concrete matrix, 102- graphite lubrication layer, 103- anti-corrosion and wear-resistant layer, 104- glass fiber mesh cloth reinforcement layer, 105- waterproof and antifreeze layer, 2- stepped overlap structure, 3- elastic buffer layer, 4- stainless steel clamp, 5- thermal insulation rubber gasket, 6- stainless steel flexible locking belt, 7- nano aerogel felt, 8- HDPE waterproof membrane. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] See also Figure 1-4 The present invention provides a technical solution: an assembled foam concrete pipe insulation structure, comprising: At least two prefabricated pipe sections, each comprising symmetrically spliced prefabricated insulation units 1, each of which is spliced together by a stepped overlap structure 2, with an elastic buffer layer 3 provided on the overlap surface. The prefabricated insulation units 1 are composed of a foamed concrete matrix 101, which contains cement, a foaming agent, basalt fiber, calcined coal gangue, and silty clay; The inner wall of the prefabricated thermal insulation unit 1 is sequentially covered with a graphite lubricating layer 102 and an anti-corrosion and wear-resistant layer 103, and the outer wall is sequentially covered with a glass fiber mesh reinforcement layer 104 and a waterproof and antifreeze layer 105; A stainless steel clamp 4 is wrapped around the outside of the overlapped portion of the prefabricated thermal insulation unit 1, and a thermal insulation rubber gasket 5 is provided between the prefabricated thermal insulation unit 1; Stainless steel flexible locking belt 6, embedded in the reserved groove of the outer wall of the prefabricated thermal insulation unit 1 through nylon insulation sleeve bolts, used to connect adjacent assembled pipeline sections; The joints between adjacent assembled pipe sections are filled with nano-aerogel felt 7 and covered with HDPE waterproof membrane 8; Specifically, the friction coefficient of the graphite lubricating layer 102 is ≤ 0.1, and the allowed axial sliding displacement of the pipeline is ≤ 5 mm; The anti-corrosion and wear-resistant layer 103 is an epoxy resin coating or a polyurethane elastomer layer with a thickness of 0.1-0.5 mm; The fiberglass mesh reinforcement layer 104 has a mesh density of 4-8 meshes / inch; The waterproof and antifreeze layer 105 is a HDPE film or a sprayed polyurea layer, and the thickness of the HDPE film is 1.0-1.5 mm; Specifically, the surface of the stainless steel clamp 4 is coated with a ceramic coating, the coating composition includes Al2O360-70wt%, SiO220-30wt%, and the thickness is 30-80μm. Specifically, the step height of the stepped overlapping structure 2 is 10-25 mm, the overlapping length is ≥50 mm, and the step inclination angle is 30°-45°; Specifically, the stainless steel flexible locking belt 6 has a width of 80-100 mm and a thickness of 1.5-2.0 mm, and is coated with a ceramic coating on the surface. The coating composition includes Al2O3 60-70 wt%, SiO2 20-30 wt%, and a thickness of 30-80 μm. Specifically, the elastic buffer layer 3 is a closed-cell rubber or silicone rubber gasket; A method for preparing an assembled foam concrete pipe insulation structure comprises the following steps: S1, preparation of prefabricated insulation unit 1 S11, raw material ratio: mix 20-30 parts of calcined coal gangue, 10-20 parts of silty clay, 0.5-2.5 parts of basalt fiber and 50-55 parts of cement, add 3-6 parts of polymer composite cement foaming agent, and the water-binder ratio is 0.4-0.55; S12, mixing and foaming: dry mixing for 3 minutes, adding water and wet mixing for 5 minutes, and injecting into the foaming machine to generate foamed concrete slurry; S13, mold forming: pouring the slurry into a steel mold with a pre-prepared anti-corrosion layer on the inner wall, and vibrating and compacting it; S14, steam curing: curing for 28 days at a constant temperature and relative humidity > 95% to form a prefabricated insulation unit 1 with an absolute dry density of 750-850 kg / m³ and a compressive strength ≥ 2.0 MPa; S2, processing of stepped mortise and tenon joint structures S21, mortise and tenon forming: Process stepped mortise and tenon joints at both ends of the prefabricated insulation unit 1, with a step height of 10-25 mm, an inclination angle of 30°-45°, and an overlap length ≥50 mm; S22, buffer layer installation: embed closed-cell rubber or silicone rubber pads on the mortise and tenon contact surfaces to absorb frost heave displacement energy and block thermal bridge transmission; S23, lock buckle groove reservation: mill a lock buckle belt installation groove with a width of 85 mm and a depth of 10 mm along the outer wall of the prefabricated thermal insulation unit 1; S3, stainless steel flexible locking system assembly S31, locking belt fixing: insert the stainless steel flexible locking belt 6 into the reserved groove. The thickness of the stainless steel locking belt is 1.5-2.0mm and the width is 80-100mm. Insert the nylon insulation sleeve bolt; S32, preload control: applied torque 18N·m, axial displacement allowed ±5mm, and a flexible locking system to compensate for thermal expansion and contraction of the pipe; S4, Joint thermal bridge blocking and sealing S41, aerogel filling: filling the joints of adjacent units with nano-aerogel felt 7 to block heat flow transfer; S42, HDPE membrane coating: using 1.0-1.5mm thick HDPE waterproof membrane 8 hot melt welding; S43, external wall spraying: the external wall of the entire pipeline is sprayed with polyurea elastomer with a thickness of 2.5mm to enhance waterproof and anti-freeze performance; Specifically, in step S3, after the stainless steel flexible locking belt 6 is installed, it is surface treated by spraying an Al2O3-SiO2 ceramic coating with a thickness of 30-80 μm to improve corrosion resistance; Specifically, in step S41, the nano-aerogel felt 7 has a thickness of 10-20 mm and a thermal conductivity of ≤0.018 W / (m·K); Specifically, in step S42, the HDPE waterproof membrane 8 is welded at a temperature of 200°C, covering the seam with a weld width of 25 mm to prevent moisture intrusion.

[0025] The present invention is particularly suitable for pipeline construction in cold regions. Through reasonable selection of insulation materials and joint design, it provides an efficient solution for balancing pipeline insulation and strength. It makes full use of industrial solid waste and cheap silty clay to replace cement, which is environmentally friendly while also reducing costs. The use of prefabricated insulation units and modular assembly of insulation layers effectively reduces construction difficulty and subsequent maintenance costs. The prefabricated foam concrete insulation composite structure of the present invention includes the following components: Prefabricated insulation unit 1: A foam concrete matrix made of cement, calcined coal gangue, silty clay, basalt fiber and foaming agent. The core insulation adopts low-density and low thermal conductivity materials to achieve efficient thermal insulation. The 28-day compressive strength is ≥2.0Mpa, which can fully resist the frost heave soil pressure and achieve the role of compressive support. Coal gangue is used to replace 30% of cement to dispose of industrial solid waste and achieve the purpose of carbon reduction.

[0026] Stepped lap joint structure 2: It consists of a stepped mortise and tenon structure processed at the unit ends and embedded with a closed-cell rubber buffer layer 3. It resists the lateral shear force caused by frost heave through mechanical interlocking. The rubber layer is used to absorb the frost heave displacement energy and block the transmission of thermal bridges.

[0027] Stainless steel flexible locking belt 6 and flexible locking system: It consists of a stainless steel flexible locking belt 6 covering the overlapped part, combined with an axial flexible locking belt and a nylon insulation sleeve; the clamp is used to provide radial restraint force for the pipeline to prevent the unit from detaching; the flexible locking belt provides displacement compensation (±5mm) for the insulation unit, allowing the pipeline to expand and contract due to heat.

[0028] Joint thermal bridge blocking system: It is composed of nano-aerogel felt 7 and HDPE waterproof membrane 8. Aerogel is used to fill the joints to block heat flow; HDPE membrane is used for hot-melt welding to prevent moisture intrusion and frost heave. Composite protective layer of inner and outer walls: composed of a graphite lubricating layer 102, an anti-corrosion and wear-resistant layer 103, a glass fiber mesh cloth reinforcement layer 104 and a waterproof and antifreeze layer 105. The inner wall anti-corrosion and wear-resistant layer 103 is made of epoxy resin to reduce the friction coefficient of the pipeline and prevent corrosion of the water pipe wall; the outer wall waterproof and antifreeze layer 105 is made of sprayed polyurea or HDPE film to block external water vapor penetration; the glass fiber mesh cloth reinforcement layer 104 is made of 4-8 mesh / inch glass fiber mesh to inhibit frost heave and cracking of the outer wall and improve the overall tensile strength.

[0029] In the following embodiments of the present invention, the technical solution of the present invention is illustrated in detail using calcined coal gangue from an industrial park in the northern Xinjiang Uygur Autonomous Region and silty clay commonly found in the mountainous areas of Xinjiang, a polymer cement foaming agent produced by a company in Weihai, Shandong, PO 42.5 ordinary Portland cement produced by Tianneng Cement Co., Ltd., and basalt fiber provided by a new materials company in Xinjiang as examples.

[0030] Example 1

[0031] The product is made from the following raw materials in parts by mass: 20 parts of calcined coal gangue, 20 parts of silty clay, 0.5 parts of basalt fiber, 54.5 parts of cement, 5 parts of polymer composite cement foaming agent, and a water-cement ratio of 0.4.

[0032] Example 2

[0033] The product is made of the following raw materials in parts by mass: 30 parts of calcined coal gangue, 10 parts of silty clay, 0.5 parts of basalt fiber, 54.5 parts of cement, 5 parts of polymer composite cement foaming agent, and a water-binder ratio of 0.55.

[0034] Example 3

[0035] The product is made of the following raw materials in parts by mass: 20 parts of calcined coal gangue, 20 parts of silty clay, 0.5 parts of basalt fiber, 54.5 parts of cement, 5 parts of polymer composite cement foaming agent, and a water-cement ratio of 0.55.

[0036] In summary, the pipeline insulation material provided in Examples 1-3 of the present invention utilizes silty clay and calcined coal gangue as alternative raw materials, maintains a certain strength while still having good thermal insulation performance, and is a green, inexpensive, and cost-effective insulation material.

[0037] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0038] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An assembled foam concrete pipe insulation structure, characterized in that: include: At least two assembled pipe sections, the assembled pipe sections comprising symmetrically spliced prefabricated insulation units (1), the prefabricated insulation units (1) being spliced together via a stepped overlap structure (2), the overlap surface being provided with an elastic buffer layer (3), the prefabricated insulation units (1) being composed of a foamed concrete matrix (101), the foamed concrete matrix (101) comprising cement, a foaming agent, basalt fiber, calcined coal gangue, and silty clay; The inner wall of the prefabricated thermal insulation unit (1) is sequentially covered with a graphite lubricating layer (102) and an anti-corrosion and wear-resistant layer (103), and the outer wall is sequentially covered with a glass fiber mesh reinforcement layer (104) and a waterproof and antifreeze layer (105); A stainless steel clamp (4) is wrapped around the outside of the overlapped portion of the prefabricated thermal insulation unit (1), and a thermal insulation rubber gasket (5) is provided between the prefabricated thermal insulation unit (1); A stainless steel flexible locking belt (6) is embedded in a reserved groove on the outer wall of the prefabricated thermal insulation unit (1) through a nylon thermal insulation sleeve bolt, and is used to connect adjacent assembled pipeline sections; The joints between adjacent assembled pipeline sections are filled with nano-aerogel felt (7) and covered with HDPE waterproof membrane (8).

2. The assembled foam concrete pipe insulation structure according to claim 1, characterized in that: The graphite lubricating layer (102) has a friction coefficient of ≤0.1 and allows an axial sliding displacement of the pipeline of ≤5 mm; The anti-corrosion and wear-resistant layer (103) is an epoxy resin coating or a polyurethane elastomer layer with a thickness of 0.1-0.5 mm; The fiberglass mesh reinforcement layer (104) has a mesh density of 4-8 meshes / inch; The waterproof and antifreeze layer (105) is a HDPE film or a sprayed polyurea layer, and the thickness of the HDPE film is 1.0-1.5 mm.

3. The assembled foam concrete pipe insulation structure according to claim 1, characterized in that: The surface of the stainless steel clamp (4) is coated with a ceramic coating, the coating composition includes Al2O3 60-70wt%, SiO2 20-30wt%, and the thickness is 30-80μm.

4. The assembled foam concrete pipe insulation structure according to claim 1, characterized in that: The step height of the stepped overlapping structure (2) is 10-25 mm, the overlapping length is ≥50 mm, and the step inclination angle is 30°-45°.

5. The assembled foam concrete pipe insulation structure according to claim 1, characterized in that: The stainless steel flexible locking belt (6) has a width of 80-100 mm and a thickness of 1.5-2.0 mm, and is coated with a ceramic coating on the surface. The coating composition includes Al2O3 60-70 wt%, SiO2 20-30 wt%, and a thickness of 30-80 μm.

6. The assembled foam concrete pipe insulation structure according to claim 1, characterized in that: The elastic buffer layer (3) is a closed-cell rubber or silicone rubber gasket.

7. The method for preparing an assembled foam concrete pipe insulation structure according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1, Preparation of prefabricated insulation unit (1) S11, raw material ratio: mix 20-30 parts of calcined coal gangue, 10-20 parts of silty clay, 0.5-2.5 parts of basalt fiber and 50-55 parts of cement, add 3-6 parts of polymer composite cement foaming agent, and the water-binder ratio is 0.4-0.55; S12, mixing and foaming: dry mixing for 3 minutes, adding water and wet mixing for 5 minutes, and injecting into the foaming machine to generate foamed concrete slurry; S13, mold forming: pouring the slurry into a steel mold with a pre-prepared anti-corrosion layer on the inner wall, and vibrating and compacting it; S14, steam curing: curing for 28 days at a constant temperature and relative humidity >95% to form a prefabricated insulation unit (1) with an absolute dry density of 750-850 kg / m³ and a compressive strength ≥2.0 MPa; S2, processing of stepped mortise and tenon joint structures S21, mortise and tenon forming: processing stepped mortise and tenon at both ends of the prefabricated insulation unit (1), with a step height of 10-25 mm, an inclination angle of 30°-45°, and an overlap length ≥50 mm; S22, buffer layer installation: embed closed-cell rubber or silicone rubber pads on the mortise and tenon contact surfaces to absorb frost heave displacement energy and block thermal bridge transmission; S23, lock slot reservation: mill a lock belt installation slot with a width of 85 mm and a depth of 10 mm along the outer wall of the prefabricated insulation unit (1); S3, stainless steel flexible locking system assembly S31, locking belt fixing: embed the stainless steel flexible locking belt (6) into the reserved groove, the stainless steel locking belt has a thickness of 1.5-2.0mm and a width of 80-100mm, and inserts the nylon insulation sleeve bolt; S32, preload control: applied torque 18N·m, allowable axial displacement ±5mm, and compensate for thermal expansion and contraction of the pipe through a flexible locking system; S4, Joint thermal bridge blocking and sealing S41, aerogel filling: filling the joints of adjacent units with nano-aerogel felt (7) to block heat flow transfer; S42, HDPE membrane coating: using 1.0-1.5mm thick HDPE waterproof membrane (8) hot melt welding; S43, external wall spraying: The external wall of the entire pipeline is sprayed with polyurea elastomer with a thickness of 2.5mm to enhance the waterproof and anti-freeze performance.

8. The assembled foam concrete pipe insulation structure according to claim 7, characterized in that: In step S3, after the stainless steel flexible locking belt (6) is installed, it is surface treated by spraying an Al2O3-SiO2 ceramic coating with a thickness of 30-80 μm to improve corrosion resistance.

9. The assembled foam concrete pipe insulation structure according to claim 7, characterized in that: In step S41, the nano aerogel felt (7) has a thickness of 10-20 mm and a thermal conductivity of ≤0.018 W / (m·K).

10. The assembled foam concrete pipe insulation structure according to claim 7, characterized in that: In step S42, the HDPE waterproof membrane (8) is welded at a temperature of 200°C, covering the seam with a weld width of 25 mm to prevent moisture intrusion.

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