Thermal insulation construction method for aqueduct
By using rigid foam polyurethane spray and composite insulation structure in the aqueduct project, the problem of water seepage caused by temperature changes in the aqueduct was solved, and the stability and waterproofness of the aqueduct under cold wave conditions were improved.
Patent Information
- Application Number
- CN202511128130.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-13
- Publication Date
- 2025-09-23
AI Technical Summary
The problem of water leakage in the expansion joints of the aqueduct body concrete caused by temperature changes is difficult to solve effectively, especially during the cold wave period in winter.
On-site sprayed rigid foam polyurethane is used as the core insulation material, combined with a composite structure of rubber powder particle leveling layer, anti-cracking polymer mortar and glass fiber mesh cloth, plus an insulation cover to form full-section protection, reduce heat exchange and adapt to thermal expansion and contraction deformation.
It effectively reduces the heat exchange between the aqueduct and the outside world, improves its crack resistance and waterproofness, reduces water seepage in expansion joints, and ensures that the structure remains stable under extreme cold wave conditions.
Smart Images
Figure CN120683837A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of thermal insulation construction, in particular to an aqueduct thermal insulation construction method. Background Art
[0002] Since the aqueduct project began operating, the thermal expansion and contraction of the concrete in the aqueduct has caused leakage in numerous expansion joints. Despite years of treatment with SK hand-scraped polyurea waterproofing, replacement of waterstops, and drilled elastic epoxy grouting, some expansion joints still experience moisture and water seepage during winter. To investigate the correlation and impact of adding insulation on the opening and closing of aqueduct expansion joints and water seepage, a new aqueduct insulation construction method was urgently needed. Summary of the Invention
[0003] In view of this, in order to solve the technical problem in the prior art caused by the temperature influence on the concrete of the aqueduct body, the present invention provides an aqueduct insulation construction method, which adopts on-site spraying rigid foam polyurethane as the core insulation material, which has the characteristics of low thermal conductivity and high strength, and can effectively reduce the heat exchange between the trough body and the external environment; at the same time, through the composite structure of the rubber powder particle leveling layer, the anti-cracking polymer mortar and the glass fiber mesh cloth, the crack resistance, waterproofness and durability of the insulation system are improved, which adapts to the thermal expansion and contraction deformation requirements of the aqueduct concrete structure.
[0004] To achieve the above object, the present invention provides the following technical solutions:
[0005] An aqueduct insulation construction method comprises the following steps:
[0006] Step (1), base surface cleaning;
[0007] Step (2), spraying rigid foam polyurethane;
[0008] Step (3), a rubber powder particle leveling layer, applying an interface agent on the polyurethane surface, and after the interface agent solidifies, applying the rubber powder particles on the polyurethane surface;
[0009] Step (4), the anti-cracking polymer mortar and the glass fiber mesh cloth are glued together. After the rubber powder particles solidify, the anti-cracking polymer mortar is constructed as the bottom layer, and the glass fiber mesh cloth is pressed into the anti-cracking polymer mortar;
[0010] Step (5), construction of the anti-cracking polymer mortar surface layer: after the bottom layer of anti-cracking polymer mortar is initially solidified, another layer of anti-cracking polymer mortar is applied on the surface to form a plastering layer.
[0011] Preferably, it also includes:
[0012] Step (6): applying thermal insulation material on the outer surface of the aqueduct.
[0013] Preferably, the thermal insulation material is thermal insulation cotton, and the external application thickness is 10mm to 50mm.
[0014] Preferably, the external application thickness is 50 mm.
[0015] Preferably, it also includes:
[0016] Step (7): adding a heat-insulating cover plate above the aqueduct water body.
[0017] Preferably, the thermal insulation cover is a PC sun panel with a density of 1200 kg / m 3 , the specific heat capacity is 1172J / (kg·K), the thermal conductivity is 0.2W / (m·K), and the thickness is 20mm.
[0018] Preferably, in step (2), the thickness of the sprayed polyurethane is 3 cm to 5 cm.
[0019] Preferably, in step (3), the thickness of the leveling layer is not less than 15 mm.
[0020] Preferably, in step (5), the thickness of the finishing layer is 5 mm to 7 mm.
[0021] Preferably, in step (4), the length of a single glass fiber mesh cloth is not greater than 6m, and when paving and overlapping, the transverse overlap width is ≥100mm, and the longitudinal overlap width is ≥80mm.
[0022] Compared with the prior art, the present invention has the following beneficial effects:
[0023] (1) Strong adaptability of material properties
[0024] Use on-site sprayed rigid foam polyurethane as the core insulation material, with a thermal conductivity of ≤0.024W / (m·k) and an apparent density of ≥35kg / m 3 It has the characteristics of low thermal conductivity and high strength, which can effectively reduce the heat exchange between the trough body and the external environment; at the same time, through the composite structure of rubber powder particle leveling layer, anti-cracking polymer mortar and glass fiber mesh cloth, the crack resistance, waterproofness and durability of the insulation system are improved, adapting to the thermal expansion and contraction deformation requirements of the aqueduct concrete structure.
[0025] (2) Differentiated design and precise optimization
[0026] In view of the differences in heat loss in different spans (20m span, 30m span) and different positions (sunny side, shady side, bottom of the base plate) of the aqueduct, a graded thickness design (3cm~5cm) is adopted to ensure the insulation effect of key parts such as the shady side and base plate, avoid material waste, and achieve a balance between insulation performance and economy.
[0027] (3) Construction technology is efficient and controllable
[0028] Mechanized spraying construction: Using a polyurethane sprayer for on-site spraying can quickly cover the complex surface of the aqueduct, ensuring a continuous and seamless insulation layer, thereby improving construction efficiency;
[0029] Layered process ensures quality: through the standardized process of base surface cleaning → spraying polyurethane → leveling layer → anti-cracking mortar (including mesh cloth), each layer of process must be supervised and accepted, combined with the "three inspections system" to strictly control the construction quality and reduce hidden dangers such as hollowing and cracking.
[0030] (4) Targeted solutions to engineering pain points
[0031] By adding an external insulation system that directly acts on the outer surface of the aqueduct, the temperature fluctuations of the aqueduct during cold waves can be effectively reduced, the opening and closing of expansion joints and water seepage can be reduced, providing data support for subsequent research on the impact of insulation measures on structural stability, and targeted solutions to the problem of water seepage treatment in winter over the years.
[0032] (5) Composite insulation design significantly improves cold resistance
[0033] A composite solution combining spray-coated rigid polyurethane foam and an insulated cover effectively slows water temperature drops under extreme cold wave conditions (-18°C, 1.9 m / s, and no sunlight). Numerical simulations show that without insulation measures, the water at the aqueduct outlet would drop below 0°C and freeze within 24 hours. However, the composite insulation solution maintained water temperatures above 0°C during the three-day cold wave, with only the water temperature nearing freezing at the outlet by the 84th hour, significantly reducing the risk of ice jams and waterlogging.
[0034] (6) Material properties and thickness optimization balance insulation effect and economy
[0035] Core material properties: The thermal conductivity of the selected rigid polyurethane foam is ≤0.024W / (m·K), and the apparent density is ≥35kg / m 3 , with both low thermal conductivity and structural stability, it can effectively block the heat exchange between the tank and the outside world;
[0036] Precise thickness design: By simulating the effects of insulation cotton of different thicknesses (10mm, 20mm, 30mm, 50mm), 50mm was finally selected as the thickness of the outer insulation layer. This not only meets the requirements of the "Technical Specifications for Rigid Foam Polyurethane Thermal Insulation and Waterproofing Engineering" but also reduces material costs while ensuring thermal insulation performance.
[0037] (7) Full-section insulation system enhances structural protection
[0038] The insulation system comprises a multi-layered structure consisting of sprayed rigid polyurethane foam, a leveling layer of rubber powder particles, a crack-resistant polymer mortar, and a fiberglass mesh. Combined with a 20mm-thick PC polycarbonate insulation cover and external cladding, it provides full-section protection. This structure not only enhances the aqueduct's surface crack resistance and water resistance, but also further reduces heat convection between the water and the outside world through the air dielectric layer, adapting to the complex heat transfer environment during cold snaps.
[0039] (8) Numerical simulation to verify the scientific feasibility of the scheme
[0040] Based on the coupled multi-physics theory of heat conduction, convection, and radiation, a three-dimensional model of the aqueduct, water body, and insulation material was established, systematically simulating the temperature field distribution under different operating conditions (ambient temperature, wind speed, and solar radiation). The results showed that the composite insulation solution can increase the minimum temperature of the aqueduct from -6°C (without insulation) to -1°C (with 50mm of insulation), and the insulation cover effectively blocks direct contact between cold air and the water, verifying the effectiveness of the solution from a thermodynamic perspective. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Figure 1 The temperature field of the aqueduct outlet section covered with insulation materials of different thicknesses;
[0042] Figure 2 The temperature field of the aqueduct outlet body covered with insulation materials of different thicknesses;
[0043] Figure 3 This is a schematic diagram of the thermal insulation cover setting;
[0044] Figure 4 This is the model diagram after adding the insulation cover;
[0045] Figure 5 is the water outlet temperature field. DETAILED DESCRIPTION
[0046] 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 some embodiments of the present invention, not all 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.
[0047] An aqueduct insulation construction method comprises the following steps:
[0048] Step (1), base surface cleaning, specifically: two plans are formulated for cleaning the aqueduct base surface, and the appropriate plan is selected for construction according to the actual situation on site.
[0049] 1) Use a high-pressure water gun to flush the surface of the aqueduct, and use a handheld angle grinder to grind the parts of the surface that are difficult to flush, to ensure that the surface of the aqueduct is free of dust, slag and other debris.
[0050] 2) Use a handheld angle grinder to grind off impurities such as surface slag and cement slurry that are difficult to remove, and then use a high-pressure air blower to clean the dust, cobwebs and other debris on the surface of the aqueduct.
[0051] After the base surface is cleaned, notify the supervision unit for acceptance and proceed to the next construction process after passing the acceptance.
[0052] Step (2), spraying rigid foam polyurethane, specifically, can be as follows: after the concrete base surface is cleaned, the spraying equipment can be placed on the ground or on an aerial work platform of suitable height according to the height of the spraying surface, and the pipeline and spray gun are pulled to the work surface for construction. The polyurethane is transported from the pipeline to the spray gun through the high pressure of the equipment for spraying. When spraying, two layers of foundation are first laid in a certain order to increase the adhesion between the base surface and the polyurethane insulation layer. After spraying the base layer, continuous spraying can be performed until the required thickness is reached. At the same time, a thickness measuring ruler made of steel wire can be used to pierce the polyurethane foam to measure the thickness. If the thickness is not reached locally, it can be sprayed again until the required thickness is reached.
[0053] Step (3), the rubber powder particle leveling layer, brush the interface agent on the polyurethane surface, and after the interface agent solidifies, apply the rubber powder particles on the polyurethane surface. Specifically, it can be as follows: first, brush the interface agent on the polyurethane surface, and at the same time make vertical and straight fixed points. After the interface agent solidifies, the rubber powder particles can be constructed. Add the corresponding water according to the preparation standard to the rubber powder particles and mechanically stir them. The stirring time should not be less than 10 minutes to ensure that the stirring is uniform. Apply the stirred rubber powder particles on the polyurethane surface in multiple times. The thickness is based on the fixed points. Ensure the surface is flat.
[0054] Step (4), anti-cracking polymer mortar and glass fiber mesh cloth are pasted together for construction. After the rubber powder particles are solidified, the anti-cracking polymer mortar is constructed on the bottom layer, and the glass fiber mesh cloth is pressed into the anti-cracking polymer mortar. Specifically, the anti-cracking polymer mortar can be constructed only after the rubber powder particles are solidified. The anti-cracking polymer mortar plastering is divided into a bottom layer and a surface layer. The bottom layer is 2-3mm thick and has a uniform thickness. The glass fiber mesh cloth is pressed into the anti-cracking polymer mortar. The surface layer is required to be kneaded out of slurry and to be flat and compacted. It is strictly forbidden to wrinkle the glass fiber mesh cloth. The length of a single mesh cloth is not more than 6m. When paving and overlapping, the horizontal overlap width is ≥100mm and the vertical overlap width is ≥80mm.
[0055] Step (5), construction of the anti-cracking polymer mortar surface layer, after the bottom layer of anti-cracking polymer mortar is initially solidified, another layer of anti-cracking polymer mortar is applied on its surface to form a plastering layer. Specifically, after the bottom layer of anti-cracking polymer mortar is initially solidified, another layer of anti-cracking polymer mortar is applied on its surface with a thickness of 2-3mm. It is advisable that the mesh cloth is evenly covered and the outline of the mesh cloth is slightly visible. The total thickness of the anti-cracking polymer mortar is controlled within 5-7mm, and the surface mortar must not be rubbed continuously to avoid forming hollows. The mortar plastering construction should be intermittent at natural disconnections to facilitate the overlap of subsequent construction. In order to intermittently construct on a continuous surface, the surface mortar should not completely cover the laid mesh cloth, and should be left in a step-shaped manner with the mesh cloth bottom layer mortar to avoid the flatness of the mesh cloth overlap exceeding the deviation.
[0056] The operation requirements of the aqueduct insulation construction method provided by the present invention are as follows:
[0057] (1) During construction, strictly abide by the "Technical Specifications for Rigid Foam Polyurethane Thermal Insulation and Waterproofing Engineering" (GB50404-2017) and other current national and industry standards, specifications, and regulations.
[0058] (2) The construction environment temperature for spraying rigid foam polyurethane should not be lower than 10℃; the wind force should not be greater than level three; when spraying rigid foam polyurethane, the relative humidity of the air should be less than 85%. It is strictly prohibited to construct on rainy or snowy days. When it rains or snows during construction, the working surface should be covered.
[0059] (3) The base layer meets the following requirements:
[0060] The wall base is solid, flat, dry and clean;
[0061] (4) When spraying rigid foam polyurethane, shielding measures should be taken for the water surface in the aqueduct and the areas outside the working surface that are easily contaminated by flying materials.
[0062] (5) The thickness of the leveling layer in the sprayed rigid foam polyurethane external insulation system shall not be less than 15 mm; the finishing layer shall completely cover the insulation material, the thickness of the finishing layer shall be 5 mm to 7 mm and shall be fully covered with glass fiber mesh cloth.
[0063] (6) The performance indicators of anti-cracking polymer plaster mortar, rubber powder particle leveling layer and glass fiber mesh are shown in the table below.
[0064] (7) Strengthen fire prevention management during the construction process. During the spraying construction, welding, cutting and other hot work are strictly prohibited. If there are no reliable fire prevention measures on the polyurethane insulation layer, hot melting or hot bonding methods shall not be used on it. Electrical lines should not pass through or be laid in rigid foam polyurethane insulation materials.
[0065] (8) The rigid polyurethane foam external insulation system has the ability to adapt to the normal deformation of the base layer, withstand its own weight, wind load and repeated effects of outdoor climate without cracking, falling off or hollowing, and has anti-seepage properties and the ability to prevent the spread of fire.
[0066] In the present invention, the thickness of the sprayed polyurethane is preferably 3cm to 5cm. In one embodiment of the present invention, based on the principle of taking into account both 20m spans and 30m spans, 22 to 24 spans are selected for the 20m span section, and 41 to 46 spans are selected for the 30m span section. An on-site spraying of rigid foam polyurethane is adopted as the external insulation measure for the aqueduct. The insulation layer thickness of the sunny side (south side) side wall of spans 22 to 24 and 41 to 42 of the aqueduct is designed to be 3cm, and the insulation layer thickness of the shady side (north side) and the bottom surface of the base plate is 4cm. The insulation layer thickness of the sunny side (south side) side wall of spans 43 to 46 of the aqueduct is 4cm, and the insulation layer thickness of the shady side (north side) and the bottom surface of the base plate is 5cm.
[0067] The physical properties of the rigid polyurethane foam provided by the present invention meet the indicators in Table 1 below:
[0068] Table 1 Physical properties of rigid foam polyurethane
[0069] project unit index Apparent density <![CDATA[kg / m 3 ]]> ≥35 Thermal conductivity (average temperature 25°C) W / (m·k) ≤0.024 Dimensional stability (70℃, 48h) ％ ≤1.5 Tensile bond strength (with cement mortar, room temperature) MPa ≥0.10 Water absorption ％ ≤3.0 Combustion performance grade - <![CDATA[Not less than Class B2]]>
[0070] The plastering layer should completely cover the insulation material. The thickness of the plastering layer should be 5mm to 7mm and fully covered with glass fiber mesh. The performance indicators of the anti-cracking polymer mortar, rubber powder particle leveling layer and glass fiber mesh should meet the indicators shown in Table 2:
[0071] Table 2 Performance index of anti-cracking polymer mortar
[0072]
[0073]
[0074] Table 3 Performance index of rubber powder particle leveling layer
[0075]
[0076] Table 4 Glass fiber mesh performance index table
[0077]
[0078] The present invention also includes:
[0079] Step (6): applying a heat-insulating material on the outer surface of the aqueduct. The heat-insulating material is preferably heat-insulating cotton, and the thickness of the heat-insulating material is preferably 10 mm to 50 mm, and more preferably 50 mm.
[0080] The present invention also includes:
[0081] Step (7): Add a heat-insulating cover plate above the aqueduct water body. The heat-insulating cover plate material is PC sun board with a density of 1200kg / m 3 , the specific heat capacity is 1172J / (kg·K), the thermal conductivity is 0.2W / (m·K), and the thickness is 20mm.
[0082] The calculated results of the temperature field at the aqueduct outlet and the aqueduct body with different thicknesses of insulation materials are as follows: Figure 1 and Figure 2 shown.
[0083] The results show that after a day of cold wave, when the aqueduct is covered with 10mm, 20mm and 30mm thick insulation cotton to transport water, the lowest temperature of the aqueduct body at the outlet can reach -4, -3 and -2℃ respectively, and the water in the aqueduct will still reach 0℃ and freeze before reaching the aqueduct outlet; when the aqueduct is covered with 50mm thick insulation cotton to transport water, the lowest temperature of the aqueduct body near the outlet can reach -1℃, but the water temperature will still reach 0℃ before reaching the outlet, and ice will still occur at the outlet.
[0084] The results show that although the aqueduct covered with thermal insulation materials can alleviate the heat loss problem of the aqueduct body, the water surface is still prone to ice formation during cold waves due to the direct contact between cold air and the water body. Therefore, it is recommended to add a thermal insulation cover above the aqueduct water body while covering it with thermal insulation materials, such as Figure 3 shown.
[0085] The temperature change of the aqueduct after it is covered with insulation cover and insulation material is numerically simulated. The model and grid division are as follows: Figure 4 As shown, there is air medium between the water body and the cover plate.
[0086] Without considering solar radiation, the temperature field results of the Caohe aqueduct covered with thermal insulation cover and thermal insulation material are as follows: Figure 5 As shown (factors such as solar radiation are not considered in the calculation):
[0087] The results of numerical simulations show that after the Caohe Aqueduct adopted the composite protection scheme of external insulation cover and polyurethane spraying, its internal water body still showed good thermal insulation performance even when it encountered extreme cold wave conditions (-18℃ / 1.9m / s / no sunshine). By comparison, under the same working conditions, when the Caohe Aqueduct did not take insulation measures, after a 24-hour cold wave, the outlet water body was below 0℃ and ice would occur; after adopting the insulation scheme, the water body maintained a temperature field above the critical value of 0℃ during the 3-day cold wave. Until the 84th hour, only the water temperature in the local side wall area at the outlet reached 0℃ and was expected to be close to freezing. Therefore, the insulation scheme of the present invention can effectively delay the cooling time of the water body and alleviate the freezing of the aqueduct. The calculation results verify the theoretical feasibility of the composite insulation scheme from a thermodynamic perspective.
[0088] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical scope disclosed in the present invention and who makes equivalent substitutions or modifications based on the technical solutions and improved concepts of the present invention shall be covered by the scope of protection of the present invention.
Claims
1. A method for heat preservation construction of aqueduct, characterized in that: The steps include: Step (1), base surface cleaning; Step (2), spraying rigid foam polyurethane; Step (3), a rubber powder particle leveling layer, applying an interface agent on the polyurethane surface, and after the interface agent solidifies, applying the rubber powder particles on the polyurethane surface; Step (4), the anti-cracking polymer mortar and the glass fiber mesh cloth are glued together. After the rubber powder particles solidify, the anti-cracking polymer mortar is constructed as the bottom layer, and the glass fiber mesh cloth is pressed into the anti-cracking polymer mortar; Step (5), construction of the anti-cracking polymer mortar surface layer: after the bottom layer of anti-cracking polymer mortar is initially solidified, another layer of anti-cracking polymer mortar is applied on the surface to form a plastering layer.
2. The aqueduct insulation construction method according to claim 1, characterized in that: Also includes: Step (6): applying thermal insulation material on the outer surface of the aqueduct.
3. The aqueduct insulation construction method according to claim 2, characterized in that: The insulation material is insulation cotton, and the external application thickness is 10mm to 50mm.
4. The aqueduct insulation construction method according to claim 3, characterized in that: The external application thickness is 50mm.
5. The aqueduct insulation construction method according to claim 2, characterized in that: Also includes: Step (7): adding a heat-insulating cover plate above the aqueduct water body.
6. The aqueduct insulation construction method according to claim 5, characterized in that: The thermal insulation cover is a PC sun panel with a density of 1200 kg / m 3 , the specific heat capacity is 1172J / (kg·K), the thermal conductivity is 0.2W / (m·K), and the thickness is 20mm.
7. The aqueduct insulation construction method according to claim 1, characterized in that: In step (2), the thickness of the sprayed polyurethane is 3 cm to 5 cm.
8. The aqueduct insulation construction method according to claim 1, characterized in that: In step (3), the thickness of the leveling layer is not less than 15 mm.
9. The aqueduct insulation construction method according to claim 1, characterized in that: In step (5), the thickness of the finishing layer is 5 mm to 7 mm.
10. An aqueduct insulation construction method according to any one of claims 1 to 9, characterized in that: In step (4), the length of a single glass fiber mesh cloth is not greater than 6m, and when paving and overlapping, the horizontal overlap width is ≥100mm and the vertical overlap width is ≥80mm.