Construction technology of polyurethane waterproof coating

Construction technology of polyurethane waterproof coating

Polyurethane waterproof coating is aging-resistant, corrosion-resistant, heat-resistant and cold-resistant, with high tensile strength, good elasticity, acid and alkali resistance, strong adhesion, and high adhesion to commercial concrete, wood, metal, ceramics and other surfaces. Then, the following is the construction technology and method of polyurethane waterproof coating I sorted for you. Welcome to read and browse.

1. Scope of application of construction technology of polyurethane waterproof coating

Polyurethane waterproof coating is aging-resistant, corrosion-resistant, heat-resistant and cold-resistant, with high tensile strength, good elasticity, acid and alkali resistance, strong adhesion, and high adhesion to commercial concrete, wood, metal, ceramics and other surfaces. Waterproof layer and base can form a whole without hollowing out. When accidental water leakage occurs, it can be scraped again with paint, saving time and effort. The construction technology of polyurethane waterproof coating compiled by Mei Cheng Coatings Company is suitable for all kinds of waterproof projects of roofs, toilets and underground buildings with protective layers.

2. Construction preparation of polyurethane waterproof coating

2. 1. main materials: component a (prepolymer) and component b (cured body)

2.2, construction tools:

Electric mixer: used to mix material A and material B.

Paint brush: used for priming paint.

Mixing barrel: used to mix material A and material B.

Roller brush: used to brush primer.

Small paint bucket: used for mixing materials.

Small trowel: used to repair the base.

Plastic scraper: used to scrape the mixture.

Oil shovel: used to clean the base.

Small iron scraper: coating and scraping mixture on complex parts.

Mop: used to clean the base.

Rubber scraper: used to scrape the mixture.

50 kg scale: used to weigh ingredients.

3. Construction technology of polyurethane waterproof coating

Basic surface treatment? Polyurethane primer? Local enhancement? Scrape polyurethane paint once, twice or three times? Surface protection or modification

4. Basic requirements and treatment

4. 1 Waterproof base shall be made of 1: 3 cement mortar according to the design requirements, and its surface shall be smooth and polished, and there shall be no defects such as unevenness, looseness, sanding and ash dropping. Drain or floor drain should be lower than the whole waterproof layer to eliminate stagnant water. The pipe with casing should be more than 20 mm above the foundation surface. Yin and Yang corners shall be made into small rounded corners with a radius of 10MM for coating construction.

4.2, all pipe fittings, sanitary equipment, floor drain or drain, etc. Must be installed firmly, with tight joints, smooth ends and no looseness.

4.3. During construction, when using traditional polyurethane waterproof coating, the waterproof base should be basically dry and the moisture content should be less than 9%. The simple measurement method is to cover the base surface with a rubber plate with an area of 1m2 and a thickness of 1.5 ~ 2.0mm, and let it stand for 2 ~ 3 hours. If there is no watermark on the covered base surface and there is no condensation watermark on the rubber sheet near the base surface, the polyurethane waterproof coating produced by Mei Cheng Coating Company has no such requirement, and construction can be carried out as long as there is no Mingshui at the base.

4.4, before construction, first with a shovel and broom will be on the surface of the grass-roots protrusions, mortar bumps and other foreign bodies to eradicate, and thoroughly clean up the dust and debris. Yin and Yang corners, pipe roots, floor drains and drains should be carefully cleaned. If oil stain and rust are found, it should be thoroughly cleaned with wire brush, sandpaper and organic solvent.

5. Construction requirements of polyurethane waterproof coating

5. 1. Priming: This process is equivalent to cold priming in traditional asphalt waterproof construction, and its purpose is to isolate the moisture of the base and prevent the waterproof coating from bulging and falling off; Strengthen the base layer, improve the bonding strength between the coating and the base layer, and prevent the coating from pinhole and other defects. Our company suggests using polyurethane primer as basic treatment.

Preparation of polyurethane primer: Polyurethane A and Polyurethane B are mixed according to the ratio of 1: 2 ~ 3 (weight ratio) (other coatings are mixed according to the ratio specified in the product manual). When the second material is thick, it can be diluted with special diluent, and it must not be diluted with acidic or oily diluent, so as not to affect the quality of the original product. When preparing, the material B is diluted and stirred for 2-3 minutes. If dilution is not needed, it can be directly mixed with group A and group B for 5- 10 minutes. It is best to lift the agitator until the uniform liquid can slowly slip from the container. At the same time, it should be noted that the materials should be covered immediately to avoid solidification and scrap, and the mixture should be prepared for use according to the actual dosage.

5.2. Local reinforcement: expansion joints, control joints, yin and yang angles, pipe joints, etc. It can be reinforced with a layer of reinforced cloth, and then the whole waterproof construction can be carried out after curing.

5.3. First coating construction: After the primer is basically dried and solidified, evenly coat a layer of coating with a plastic or rubber scraper, and the coating thickness is generally about 0.8 mm When painting and scraping, the construction retreat and painting and scraping sequence should be considered according to the size, shape and material of the construction area.

5.4. Second coating construction: After the first coating is basically solidified, the second coating is scraped on its surface, and the scraping method is the same as that of the first coating. In order to ensure the quality of waterproof engineering, the scraping direction must be perpendicular to the first layer. The interval of recoating time is determined by the temperature during construction and the curing degree of the coating (whether it is sticky by hand).

5.5. After the second coating is cured, the third coating is carried out according to the above method.

5.6. Laying protective layer or facing material: When the third coating construction is completed and not completely solidified, a small amount of clean sand particles (with a diameter not greater than 2MM) can be sprinkled on the surface to increase the bonding ability between the coating and the cement mortar to be covered. When the coating is completely cured and passes the inspection and acceptance, the construction of cement mortar protective layer or decorative layer such as ceramic tile and mosaic can be carried out.

5.7. Construction technology of "two cloths and three coats": This technology has not been widely used in the market at present. The operation method of this technology is: after the first coating, the glass fiber grid cloth is evenly spread on it and firmly bonded by the adhesion of polyurethane. After the first drying, the second drying is carried out in the same way. After all drying, the polyurethane waterproof coating shall be painted again according to the above requirements. The construction methods of toilet, kitchen and roof are consistent. It should be noted that the glass fiber grid should be laid flat. Because the space in the bathroom is relatively small, it is necessary to carry out pretreatment when laying grid cloth. Other requirements are consistent with the traditional polyurethane construction technology.

6. Precautions for Construction of Polyurethane Waterproof Coatings

6. 1. When the viscosity of the coating is too high to carry out scraping construction, a small amount of special thinner can be added for dilution to reduce the viscosity, and the addition amount shall not be greater than 10% of Party B's. (Note: If users need to dilute the polyurethane waterproof coating, they must use the thinner matched by Mei Cheng Coatings Company. If we buy other diluents such as xylene and gasoline in the market, we will not be responsible for the quality problems caused. )

6.2. Pores and bubbles: The mixing mode and time of materials did not make the materials mix evenly; During construction, a stirrer with low power and low rotation speed should be adopted. Another reason is that grassroots treatment is not clean. Before painting, the base should be carefully cleaned, and there should be no floating sand and dust, and there should be no air holes on the base. The air holes in each coating should be treated according to the process requirements to prevent leakage caused by coating damage.

6.3. Bumping: peeling, sanding, cracking and non-drying at the grass-roots level make the coating film poorly bonded; Grass-roots construction should be carefully operated and maintained. After drying at the grass-roots level, primer should be applied first. After curing, it should be painted layer by layer according to the waterproof layer construction technology.

6.4. Edge warping of coating: the edge of waterproof layer and the lap joint of sub-brush fall off from the base and become warped. The main reasons are that the base is not clean or dry, the closing operation is not careful, the sealing is not good, and the adhesion of the primer is not strong, which leads to the edge tilting. Therefore, the grassroots should be clean and dry, and the operation should be meticulous.

6.5. Damage: During the layered construction of coating waterproof layer or after all coating construction, before coating curing, someone operates activities or places tools and materials, resulting in coating damage. Scratch. The integrity of the coating should be protected during construction.

6.6, fire prevention should be paid attention to during construction, construction personnel should take protective measures, the construction site should be well ventilated to prevent solvent poisoning.

6.7. If the amount is found to be precipitated, stir it evenly before use, so as not to affect the quality.

6.8. Both materials A and B are packed in iron drums, which are flammable and toxic. Storage should be sealed and placed in a cool and dry place without strong direct sunlight.

6.9, the construction temperature should be above 5℃.

7. Quality records

7. 1, factory certificate (warranty) of various materials used and re-inspection record of entry;

7.2, take cover engineering inspection data and quality evaluation data of each process;

7.3. Data handover between processes;

7.4, roof water storage test records;

7.5, special construction scheme and technical disclosure;

7.6, construction log.

8. Analysis of Waterproof Failure of Polyurethane Waterproof Coatings

8. 1. Poor quality of materials: Due to the price competition of waterproof materials in the market, many domestic manufacturers of polyurethane materials cut corners on waterproof materials, which will reduce the physical properties of waterproof materials and lead to waterproof failure.

8.2. There is moisture on the bottom layer: As the polyurethane waterproof coating is oily waterproof material, it is necessary to confirm whether the plain surface is dry before construction, otherwise the moisture will be wrapped in it after waterproof, which will be transformed into powerful steam through sunlight, causing the peeling of the polyurethane waterproof layer.

8.3, the foundation is not clean: because before the waterproof construction, the plain floor must be clean, try not to have dust and loose substances, otherwise the waterproof layer and the base are not firmly bonded, leaving a hidden danger of leakage.

8.4. The waterproof layer of polyurethane waterproof coating is too thin: the polyurethane waterproof layer must reach a certain thickness to have waterproof effect, because the polyurethane material itself still has the characteristics of low water absorption. If the thickness of the waterproof layer is insufficient, the rain will penetrate the polyurethane waterproof layer to the bottom after several days of heavy rain. In good weather, after the sun shines, water vapor will still be generated at the bottom, causing the waterproof layer to peel off. It is best to stick glass fiber grid cloth at all corners for reinforcement to prevent leakage caused by rupture of polyurethane waterproof layer.

8.5. Lack of construction experience: waterproof construction is best operated by waterproof professional construction team, and you can't go to the hardware and building materials store to buy some waterproof materials for painting. Before waterproof construction, it is necessary to carefully judge the cause of leakage and then solve it.

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