Waterproof thermal insulation cement board and construction method thereof

Abstract

The invention discloses a waterproof thermal-insulation cement board and a construction method thereof. The waterproof heat preservation cement board comprises a cement base material layer and a polyurethane waterproof layer. The thickness of the cement base material layer ranges from 20 mm to 50 mm, and the cement base material layer is formed by pouring cement paste with the strength grade larger than or equal to C30. The polyurethane waterproof layer is attached to the surface of the cement base material layer through a coating process, and the polyurethane waterproof layer is constructed by utilizing a polyurethane composition; the polyurethane composition is prepared from 20-30 parts by weight of polyether polyol type polyurethane, 14-26 parts by weight of an organic solvent and 1-3 parts by weight of a coupling agent; the coupling agent is a silane coupling agent KH-550; the thickness of the polyurethane waterproof layer is 0.5-1mm, the percentage of closed area is greater than or equal to 95%, and the average pore size is less than or equal to 50 The waterproof thermal insulation cement board is excellent in waterproof performance, firm in interface bonding, convenient to construct and suitable for building scenes with high requirements for waterproof performance, such as building outer walls, roofs and ground engineering in a humid environment.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to waterproof and heat-insulating cement boards and their construction methods. Background Technology

[0002] Cement-based panels, as an important structural material in the construction engineering field, are widely used in building structural systems such as walls, roofs, and floors due to their high strength, low cost, and good durability. However, traditional cement-based panels have significant performance defects due to their inherent microporous structure: they exhibit high water absorption under long-term water exposure. According to current testing standards, their water absorption rate after 30 days of immersion typically exceeds 5%, making them highly susceptible to cracking and damage under freeze-thaw cycles, thus failing to meet the performance requirements of current building energy-saving design codes.

[0003] To address the aforementioned technical bottlenecks, existing solutions generally employ a composite structural system of "cement substrate + waterproof layer." For example, an asphalt-based waterproof coating is applied to the surface of a cement board to form a waterproof barrier, and polystyrene foam board is bonded together using adhesive or mechanical anchoring methods. However, this type of technical solution has two major drawbacks: First, the interfacial bonding mechanism is weak. The waterproof coating and the cement substrate mainly rely on physical adsorption to bond, lacking chemical bonding. Under long-term service environments with alternating wet and dry conditions and temperature gradient changes, the interlayer is prone to peeling and failure. Second, the construction process lacks sufficient performance control. Existing coating processes are mostly single-layer thick coatings, which are prone to internal bubbles due to uneven solvent evaporation, resulting in poor product performance stability and making it difficult to meet the long-term use requirements of high waterproofing scenarios.

[0004] Therefore, developing a new type of composite cement-based board with high-strength interfacial bonding performance, excellent waterproof integrated function and good construction adaptability has become a key technical problem that urgently needs to be solved in the field of building materials. Summary of the Invention

[0005] The purpose of this invention is to provide a waterproof and thermal insulation cement board and its construction method to solve the problems of poor waterproof performance and insufficient bonding strength between existing cement-based materials and waterproof coatings. This invention provides a waterproof and thermal insulation cement board with excellent waterproof performance, strong interfacial bonding, simple preparation and wide applicability, as well as its construction method.

[0006] The first objective of this invention is to provide a waterproof and thermally insulating cement board, comprising: a cement substrate layer and a polyurethane waterproof layer; the thickness of the cement substrate layer is 20mm to 50mm, and the cement substrate layer is formed by casting with cement slurry of strength grade ≥ C30; the polyurethane waterproof layer is attached to the surface of the cement substrate layer by a coating process, and the polyurethane waterproof layer is constructed using a polyurethane composition; the polyurethane composition is prepared by 20 to 30 parts by weight of polyether polyol type polyurethane, 14 to 26 parts by weight of organic solvent and 1 to 3 parts by weight of coupling agent; the coupling agent is silane coupling agent KH-550; the thickness of the polyurethane waterproof layer is 0.5mm to 1mm, the closed-cell rate is ≥95%, and the average pore size is ≤50μm.

[0007] The waterproof and heat-insulating cement board of the present invention, as described above, further comprises that the organic solvent is at least one of tetrahydrofuran, acetone, and methyl ethyl ketone.

[0008] The waterproof and heat-insulating cement board of the present invention, as described above, further comprises an organic solvent being a mixture of acetone and tetrahydrofuran, wherein the volume ratio of the mixture is tetrahydrofuran:acetone = (1-2):1.

[0009] The waterproof and thermal insulation cement board of the present invention, as described above, further comprises that the polyether polyol type polyurethane is at least one of polyethylene oxide type polyurethane, polypropylene oxide type polyurethane, polytetrahydrofuran type polyurethane, and polyethylene glycol glycidyl ether type polyurethane.

[0010] The second objective of this invention is to provide a construction method for waterproof and thermally insulated cement boards, comprising the following steps: Step 1, preparing the cement substrate layer: mix cement paste according to the mix ratio, pour the cement paste into a mold, and cure for 7 days until the compressive strength is ≥30MPa to form the cement substrate layer; preferably, in step 1, the water-cement weight ratio of the cement paste is 0.35 to 0.45, and the mixing time is 3 to 5 minutes.

[0011] Step 2, Applying the polyurethane waterproof layer: Dissolve polyurethane in an organic solvent, add silane coupling agent KH550, stir evenly, and then apply it to the surface of the cement substrate layer by scraping. Apply in 2 to 3 coats, with an interval of ≥4 hours between each coat. After curing at room temperature for 24 to 48 hours, the polyurethane waterproof layer is formed. Preferably, in Step 2, the thickness of the first coat is 0.2 mm to 0.3 mm, and the thickness of each subsequent coat increases by 0.2 mm to 0.3 mm. During the coating process, the ambient temperature is not lower than 5°C and the relative humidity is not higher than 85%.

[0012] Step 3, Composite Curing: The composite board formed by the cement substrate layer and the polyurethane waterproof layer is cured for 14 days at an environment of 15-30℃ and 40-65% relative humidity to obtain a waterproof and heat-insulating cement board. Preferably, in Step 3, the ambient temperature is preferably 18℃-22℃ and the relative humidity is 55%-62%.

[0013] The waterproof and heat-insulating cement board and its construction method according to the above embodiments of the present invention are applicable to building exterior walls, roofs and ground projects in damp environments, and are especially suitable for food processing workshops, seafood processing plants and other scenarios with high requirements for waterproof performance.

[0014] This invention uses polyether polyol-type polyurethane. Through the hydrolysis reaction of KH550, its three ethoxy groups combine with the hydroxyl groups of polyurethane and the abundant hydroxyl groups on the surface of cement substrate, thereby forming a strong chemical bond between the polyurethane waterproof coating and the cement substrate, solving the defect of poor interfacial bonding between the waterproof layer and the cement substrate.

[0015] The beneficial effects of this invention are: (1) Excellent waterproof performance: The present invention significantly improves the impermeability of cement board by using the high closed-cell rate (≥95%) and small pore size (≤50μm) of polyurethane waterproof layer, combined with the quantitative index of ≤1.2% water absorption rate after 30 days of underwater immersion. It can effectively resist long-term erosion in a humid environment.

[0016] (2) Strong interface bonding: Adding 1-3% silane coupling agent KH-550, the silanols formed by the hydrolysis of silane ethoxy groups react with a large number of hydroxyl groups on the surface of cement substrate and hydroxyl groups in polyether polyol type polyurethane, so that the polyurethane waterproof layer and cement substrate layer form a stable chemical bond interface with an interface bonding strength ≥2.8MPa, which solves the technical pain points of easy delamination and separation of traditional coatings and significantly extends the service life of composite board.

[0017] (3) Convenient and efficient construction: The construction process of 2-3 coats is adopted. The thickness of each coat is controllable and the interval time is clear (≥4 hours). It can be cured at room temperature without special equipment. The composite curing conditions (20±2℃, relative humidity 60±5%) are easy to achieve and suitable for industrial mass production.

[0018] (4) Wide range of applications: The product can be directly applied to building exterior walls, roofs and ground projects in damp environments. It is especially suitable for food processing workshops, seafood processing plants and other scenarios with extremely high requirements for waterproof performance. It also has strong material compatibility and can be seamlessly integrated with existing building construction systems, and has good engineering practicality. Detailed Implementation

[0019] The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the invention, and are illustrative and exemplary, and should not be construed as limiting the implementation or scope of the invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0020] The performance testing methods in the following embodiments of the present invention are as follows: Closed-cell ratio: Characterized according to GB / T10799-2008 "Determination of open-cell and closed-cell volume percentage of rigid foamed plastics".

[0021] 30-day underwater immersion water absorption rate: The water absorption rate was tested by directly immersing the sample in water at room temperature for 30 days.

[0022] Interfacial bond strength: determined according to GB / T19250-2013 "Polyurethane Waterproof Coatings" standard.

[0023] Example 1 Material preparation: C30 cement paste was selected for the cement substrate layer, with a water-cement ratio controlled at 0.35. It was thoroughly mixed by mechanical stirring for 3 minutes. The polyurethane waterproof layer adopted a polyether polyol type polyurethane system (in this embodiment, the polyether polyol type polyurethane is polyethylene oxide type polyurethane, 20 parts by weight), with 1 part by weight of silane coupling agent KH550 added as an interface modifier, and dispersed with 20 parts by weight of tetrahydrofuran as an organic solvent.

[0024] Construction process: The cement substrate layer is poured to a thickness of 20mm. After 7 days of standard curing, its compressive strength reaches 32MPa. The polyurethane waterproof layer is applied using a step-by-step scraping process. The initial application is 0.2mm thick, followed by a second application of 0.4mm thick after a 4-hour interval. The construction environment is controlled at 20℃ and 60% relative humidity. After 24 hours of curing at room temperature, a 14-day composite curing period is required (curing conditions: 20℃, 60% humidity).

[0025] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 96%, an average pore size of 45μm, and a total thickness of 0.5mm. After a 30-day underwater immersion test, the water absorption rate is 1.0%. The interfacial bonding strength is 3.0MPa.

[0026] Example 2 Material preparation: The cement substrate layer uses C35 cement paste with a water-cement ratio adjusted to 0.40 and a stirring time extended to 4 minutes; the polyurethane waterproof layer uses a polyether polyol type polyurethane system (in this embodiment, the polyether polyol type polyurethane is polypropylene oxide type polyurethane, 30 parts by weight), with 2 parts by weight of silane coupling agent KH550 added as an interface modifier, and dispersed with 14 parts by weight of acetone as an organic solvent.

[0027] Construction process: The cement substrate layer is poured to a thickness of 35mm, and after 7 days of standard curing, the compressive strength reaches 35MPa; the polyurethane waterproof layer is applied in three coats, with the first coat being 0.2mm thick, followed by two more coats after a 5-hour interval, for a total thickness of 0.7mm. The construction environment is 25℃ and 70% relative humidity, with a curing time of 36 hours at room temperature, followed by a composite curing time of 14 days at 22℃ and 55% humidity.

[0028] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 97%, an average pore size of 40μm, and a thickness of 0.8mm; the water absorption rate after 30 days of underwater immersion is 0.9%; and the interfacial bonding strength is 3.2MPa.

[0029] Example 3 Material preparation: The cement substrate layer uses C40 cement paste with a water-cement ratio of 0.45 and a mixing time of 5 minutes; the polyurethane waterproof layer uses a polyether polyol type polyurethane system (in this embodiment, the polyether polyol type polyurethane is polytetrahydrofuran type polyurethane, 28 parts by weight), with 3 parts by weight of silane coupling agent KH550 added as an interface modifier, and dispersed with 26 parts by weight of butanone as an organic solvent. In this embodiment, the polytetrahydrofuran type polyurethane is generated by reacting polytetrahydrofuran as a soft segment with isocyanate.

[0030] Construction process: The cement substrate layer is poured to a thickness of 50mm, and the compressive strength reaches 38MPa after 7 days of standard curing; the polyurethane waterproof layer is applied in two coats, the first coat being 0.3mm thick, and the second coat being 0.7mm thick after a 4-hour interval. The construction environment is 15℃ and 80% relative humidity, with a curing time of 48 hours at room temperature, followed by a composite curing time of 14 days at 18℃ and 65% humidity.

[0031] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 98%, an average pore size of 35μm, and a thickness of 1.0mm; the water absorption rate after 30 days of underwater immersion is 0.8%; and the interfacial bonding strength is 3.5MPa.

[0032] Example 4 Material preparation: The cement substrate layer uses C30 cement paste with a water-cement ratio of 0.38 and is stirred for 3.5 minutes; the polyurethane waterproof layer uses a polyether polyol type polyurethane system (in this embodiment, the polyether polyol type polyurethane is polyethylene glycol glycidyl ether type polyurethane, 26 parts by weight), with 1.5 parts by weight of silane coupling agent KH550 added as an interface modifier, and dispersed in a mixture of 20 parts by weight of tetrahydrofuran and acetone (volume ratio 1:1) as an organic solvent.

[0033] Construction process: The cement substrate layer is poured to a thickness of 25mm, and after 7 days of standard curing, the compressive strength reaches 33MPa; the polyurethane waterproof layer is applied in two coats, the first coat being 0.25mm thick, and the second coat being 0.45mm thick after a 4.5-hour interval. The construction environment is 10℃ and 50% relative humidity, with a curing time of 30 hours at room temperature, followed by a 14-day composite curing at 20℃ and 60% humidity.

[0034] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 96%, an average pore size of 48μm, and a thickness of 0.7mm; the water absorption rate after 30 days of underwater immersion is 1.1%; and the interfacial bonding strength is 3.1MPa.

[0035] Example 5 Material preparation: C35 cement paste with a water-cement ratio of 0.42 was selected for the cement substrate layer and stirred for 4.5 minutes; the polyurethane waterproof layer adopted a polyether polyol type polyurethane system (in this embodiment, the polyether polyol type polyurethane is polyethylene glycol glycidyl ether type polyurethane, 30 parts by weight), with 2.5 parts by weight of silane coupling agent KH550 added as an interface modifier, and dispersed with 20 parts by weight of a mixture of acetone and butanone (volume ratio 2:1) as an organic solvent.

[0036] Construction process: The cement substrate layer is poured to a thickness of 40mm, and after 7 days of standard curing, the compressive strength reaches 36MPa; the polyurethane waterproof layer is applied in three coats, with the first coat being 0.2mm, followed by coats of 0.3mm and 0.4mm after a 5-hour interval. The construction environment is 22℃ and 75% relative humidity, with a curing time of 40 hours at room temperature, followed by a composite curing time of 14 days at 21℃ and 58% humidity.

[0037] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 97%, an average pore size of 42μm, and a thickness of 0.9mm; the water absorption rate after 30 days of underwater immersion is 0.95%; and the interfacial bonding strength is 3.9MPa.

[0038] Comparative Example 1 Material preparation: The cement substrate layer uses C30 cement paste with a water-cement ratio controlled at 0.35, and is thoroughly mixed by mechanical stirring for 3 minutes; the polyurethane waterproof layer uses a polyether polyol type polyurethane system (in this example, the polyether polyol type polyurethane is polyethylene oxide type polyurethane, 20 parts by weight), dispersed with 20 parts by weight of tetrahydrofuran as the organic solvent. Compared with Example 1, no silane coupling agent KH550 was added.

[0039] Construction process: Same as in Example 1.

[0040] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 95% and an average pore size of 48μm; the water absorption rate after 30 days of underwater immersion is 2.1%; and the interfacial bond strength is 1.1MPa.

[0041] Comparative Example 2 Material preparation: Same as in Example 2 Construction process: The cement substrate layer is poured to a thickness of 35mm, and after 7 days of standard curing, the compressive strength reaches 35MPa; the polyurethane waterproof layer is applied in one coat with a thickness of 0.7mm. The construction environment is 25℃ and 70% relative humidity, and it is cured at room temperature for 36 hours, followed by composite curing at 22℃ and 55% humidity for 14 days.

[0042] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 86%, an average pore size of 75μm, and a thickness of 0.7mm; the water absorption rate after 30 days of underwater immersion is 3.7%; and the interfacial bond strength is less than 0.1MPa. (After the waterproof layer has cured, air bubbles appear, causing detachment at the interface, resulting in almost no bond strength.) Comparative Example 3 Material preparation: C30 cement paste was selected for the cement substrate layer, with a water-cement ratio controlled at 0.35. It was thoroughly mixed by mechanical stirring for 3 minutes. The polyurethane waterproof layer adopted a polyether polyol type polyurethane system (in this embodiment, the polyether polyol type polyurethane is polyethylene oxide type polyurethane, 20 parts by weight), with 5 parts by weight of silane coupling agent KH550 added as an interface modifier, and dispersed with 20 parts by weight of tetrahydrofuran as an organic solvent.

[0043] Construction process: exactly the same as in Example 1.

[0044] Performance test results: The polyurethane waterproof layer has a closed-cell rate of 95%, an average pore size of 38μm, and a total thickness of 0.5mm. After a 30-day underwater immersion test, the water absorption rate is 1.3%. The interfacial bonding strength is 0.3MPa.

[0045] Performance Comparison Analysis: Comparative Example 1, lacking the silane coupling agent KH550, exhibited lower interfacial bonding strength and significantly increased water absorption compared to Example 1. Comparative Example 2, employing a one-time coating process, resulted in an excessively thick polyurethane layer. The evaporation of the organic solvent tetrahydrofuran generated bubbles, reducing interfacial strength. Comparative Example 3 utilized an excessive amount of KH550; unreacted small-molecule KH550 further reduced interfacial bonding strength. These results fully demonstrate the crucial role of KH550 dosage and coating process in enhancing the interfacial bonding between polyurethane and cementitious substrates and improving waterproofing capabilities. These results fully validate the key role of KH550 in enhancing interfacial bonding and improving waterproofing performance.

[0046] The technical features disclosed above are not limited to the combinations of the disclosed features with other features. Those skilled in the art can also make other combinations of the technical features according to the purpose of the invention to achieve the purpose of the invention.

Claims

1. A waterproof and heat-insulating cement board, characterized in that, include: The system comprises a cement substrate layer and a polyurethane waterproof layer; the cement substrate layer has a thickness of 20mm to 50mm and is constructed by casting cement slurry with a strength grade ≥ C30; the polyurethane waterproof layer is applied to the surface of the cement substrate layer by a coating process and is constructed using a polyurethane composition; the polyurethane composition is prepared by 20 to 30 parts by weight of polyether polyol type polyurethane, 14 to 26 parts by weight of organic solvent and 1 to 3 parts by weight of coupling agent; the coupling agent is silane coupling agent KH-550; the polyurethane waterproof layer has a thickness of 0.5mm to 1mm, a closed-cell rate ≥ 95%, and an average pore size ≤ 50μm.

2. The waterproof and thermal insulation cement board according to claim 1, characterized in that, The organic solvent is at least one of tetrahydrofuran, acetone, and butanone.

3. The waterproof and thermal insulation cement board according to claim 1, characterized in that, The organic solvent is a mixture of acetone and tetrahydrofuran, and the volume ratio of the mixture is tetrahydrofuran:acetone = (1~2):

1.

4. The waterproof and thermally insulating cement board according to claim 1, characterized in that, The polyether polyol type polyurethane is at least one of polyethylene oxide type polyurethane, polypropylene oxide type polyurethane, polytetrahydrofuran type polyurethane, and polyethylene glycol glycidyl ether type polyurethane.

5. A construction method for a waterproof and thermally insulating cement board, characterized in that, Includes the following steps: Step 1, prepare the cement substrate layer: mix cement paste according to the mix ratio, pour the cement paste into the mold, and cure for 7 days until the compressive strength is ≥30MPa to form the cement substrate layer; Step 2, apply the polyurethane waterproof layer: Dissolve the polyurethane in an organic solvent, add the silane coupling agent KH550, stir evenly, and then apply it to the surface of the cement substrate layer by scraping. Apply in 2 to 3 coats, with an interval of ≥4 hours between each coat. After curing at room temperature for 24 to 48 hours, the polyurethane waterproof layer is formed. Step 3, Composite Curing: The composite board formed by the cement substrate layer and the polyurethane waterproof layer is cured for 14 days at an environment of 15-30℃ and 40-65% relative humidity to obtain a waterproof and heat-insulating cement board.

6. The construction method of the waterproof and thermal insulation cement board according to claim 5, characterized in that, In step 1, the water-cement weight ratio of the cement paste is 0.35 to 0.45, and the mixing time is 3 to 5 minutes.

7. The construction method of the waterproof and thermal insulation cement board according to claim 5, characterized in that, In step 2, the initial coating thickness is 0.2mm to 0.3mm, and the thickness increases by 0.2mm to 0.3mm with each subsequent coating. During the coating process, the ambient temperature is not lower than 5℃ and the relative humidity is not higher than 85%.

8. The construction method of the waterproof and thermal insulation cement board according to claim 5, characterized in that, In step 3, the ambient temperature is preferably 18℃~22℃ and the relative humidity is 55%~62%.