1 construction preparation ① requirements for base course: the plastering of base course has been completed and maintained for about 20 days, the alkaline PH value of base course is below 9, the base course has been dried (at least 15 days) and the humidity is below 8%; The surface of the grass-roots level is smooth, the angle of yin and yang is dense and distinct; There are no structural problems such as water seepage, cracks, hollowing and bubbles on the wall surface. No loose powder, no oil, grease and other adhesion. (2) Waterproof and airtight treatment has been made for the reserved joints of external walls. (3) The paint used has the factory certificate and meets the requirements of relevant national codes and standards through inspection. (4) The paint used is approved by the owner, and the model wall is approved by the owner, supervisor and design unit. ⑤ Decorative scaffolding has been set up. ⑥ Exposed iron parts at the grass-roots level have been treated with corresponding antirust treatment (galvanized or brushed with antirust paint. ⑦ Construction conditions: Because the exterior wall coating is water-based, it requires higher construction and maintenance conditions. Construction and maintenance require that the temperature be higher than 5℃ and the ambient humidity be lower than 85% to ensure good film formation. Low temperature will cause problems such as powdering and cracking of paint film, and the paint film will not dry for a long time due to environmental humidity, which will eventually lead to poor film formation. Weather factors must be considered in the construction of external walls. It doesn't rain 12 hours before painting, so as to ensure that the base is dry. It can't rain for 24 hours after painting to avoid the paint film being washed away by rain. 2 Construction method of exterior wall coating The coating system of exterior wall architectural coating in this project is divided into three layers, namely primer, first layer coating and second layer coating. Its functions are as follows: Primer: Primer seals the alkalinity of the wall, improves the adhesion of the top coat, and has a great influence on the painting performance and surface effect of the top coat. If the primer is not used, the adhesion of the paint film will be weakened, and the alkalinity of the wall will have a great impact on the performance of the topcoat, especially when the bottom surface of putty is used, which may cause problems such as powdering, yellowing and alkali penetration of the paint film, destroy the performance of the topcoat and affect the service life of the paint film. First topcoat: The main function of the first topcoat is to improve adhesion and hiding power, increase fullness and correspondingly reduce the amount of topcoat. Second topcoat: The second topcoat is the last coating in the system, which has decorative effect and resists environmental damage. 2. 1 Repair of construction technology → cleaning → putty filling, local putty scraping → smoothing → sticking glass fiber cloth → full putty scraping → smoothing → primer construction → first topcoat construction → second topcoat construction 2.2 Operation method A. Repair: 1: 3 Cement mortar (or polymer cement mortar) is used to coat the missing edges and corners of the matrix before painting. The specific methods are as follows: Empty drum-if it is a large area (greater than 10cm2), all the empty drum parts should be eradicated, cleaned up and re-used as grass roots; If it is a local empty drum (less than 10cm2), low viscosity epoxy resin should be injected to repair it. Cracks-tiny cracks shall be repaired with putty (thin batch is required when repairing, and thick brush is not allowed), and then they shall be smoothed with sandpaper after drying; For larger cracks, the cracks can be chiseled into V-shaped cracks, cleaned and made into waterproof layer, then embedded with 1: 2.5 cement mortar, dried and polished with cement sandpaper. Holes-the holes below 3mm below the surface of the base course shall be leveled with polymer cement putty, and the holes above 3mm shall be repaired with cement mortar, and then dried and smoothed. In addition, for the new cement mortar surface layer, if it is urgently needed to be painted, zinc sulfate or zinc oxide solution with the concentration of 15%-20% can be painted on the surface of the cement mortar base for several times, and the powder and floating sand deposited on the surface can be removed after drying. B, cleaning: dust, powder-can be washed with broom, brush, high-pressure water, grease-clean with neutral detergent; Mortar-Remove with shovel, scraper, etc. Mould-outdoor high-pressure water washing, clear water rinsing until dry. C. Fill putty, and scrape putty locally: if the wall surface is smooth, putty is not needed; Putty should have good strength and durability besides being easy to scrape and polish. In the construction of joint filling and local putty scraping, thin batch is required instead of thick brush. Putty is required to have good cohesiveness, durability and water resistance. The putty used is a mixture of 107 white cement slurry and 159d-20M fine sand. Construction technology when scraping putty: ① Grasp the inclination of tools when scraping and coating, and apply force evenly to ensure the putty is full. (2) In order to avoid the putty from shrinking too much, cracking and falling off, a scraping coating should not be too thick. According to the characteristics of different putty, the thickness should be 0.5 mm Don't scrape too much, so as to avoid peeling or squeezing the rubber sealing surface in the putty, which is not easy to dry. (3) Fill and fill with putty knife. When there are holes and cracks at the grass-roots level, press the blade with your forefinger, and push the putty into the defect, and scrape the putty around to make it leave no trace as far as possible. D. Polishing: ① Wet grinding is not allowed, and it must be done after the base or putty is dried, so as not to affect the operation by sticking sandpaper. ② The thickness of sandpaper depends on the hardness of the ground surface. Coarse sandpaper will produce sand marks, which will affect the final decorative effect of the coating. (3) When manually polishing, the sandpaper (cloth) should be wrapped on the polishing pad: block and pushed back and forth by the pad factory. It is not allowed to press the sandpaper with only one or two fingers, which will affect the smoothness of grinding. Mechanical polishing adopts electric grinder, sandpaper is clamped on the grinder and gently pushed on the base. It is forbidden to press hard to avoid motor overload and damage. (4) When polishing, first use coarse emery cloth or grinder to polish, and then use fine emery cloth to polish; Pay attention to the smoothness of surface. Even if the flatness of the surface meets the requirements, we should also pay attention to the roughness of the base surface and the texture after grinding. If these two situations occur, the gloss of the surface layer will cause the illusion of different shades due to light and shadow, which will affect the effect. This requires local re-leveling, and it will be used for re-leveling if necessary to achieve the same roughness. 5 For the uneven surface, the protruding part can be leveled, filled with putty, and polished with sandpaper after drying. It is required that the smoothness of the polished base should be no obvious scratches, no rough feeling, and the surface is smooth under side illumination. ⑥ Immediately after grinding, remove the surface dust to facilitate the construction of the next procedure. E, glass fiber cloth should have uniform mesh density, don't use too dense glass fiber cloth to pave; When paving, use high-concentration 107 glue from top to bottom, and scrape it off with a scraper, and scrape it off at the same time; When the glass fibers meet and rub, they should be staggered for 2-3 cm. After being leveled, it should be cut with a knife. When cutting, it must be uniform, and the glass fiber cloth should be close together to enhance the adhesion. F, scraping putty and then smoothing: polymer putty is used to smooth, the main purpose is to smooth the unevenness caused by sticking glass fiber cloth and prevent capillary cracks on the surface. Use No.0 emery cloth or grinder to smooth the surface, so that the roughness is consistent and the texture is uniform. This process requires repeated inspection and polishing until the surface looks and feels the same. G. Painting: When painting, the moisture content of the base surface shall not be greater than 8%, and the surface coating shall not be painted in case of strong wind, rain or fog. During construction, it is required to make a model wall according to the design requirements until the completion acceptance. (1), the deployment of architectural coatings All the coatings used in this project are finished products after color matching by professional manufacturers according to the colors selected by color cards. In terms of coating degree, if the coating is found to be precipitated, it must be stirred evenly. The paint shall be stirred with an electric mixer, and the stirring time shall be controlled at 8- 10 minute. (2) Painting method: During construction, the corner between the Yin and Yang wall and the downpipe shall be taken as the dividing line, and the same batch of paint shall be used for the same wall. Each layer of paint shall not be painted too thick, and the painting shall be uniform and of the same color. During coating construction, the requirements for construction and maintenance conditions are higher. The construction and maintenance temperature is higher than 5℃ and the ambient humidity is lower than 85% to ensure good film formation. Low temperature will cause problems such as powdering and cracking of paint film, and the paint film will not dry for a long time due to environmental humidity, which will eventually lead to poor film formation. Weather factors must be taken into account when building external walls. It can't rain 12 hours before painting, so as to ensure the substrate is dry. After painting, corresponding measures should be taken to prevent the paint film from being washed away by rain within 24 hours. Brush coating and roller coating are mainly used: among them, brush coating is carried out with a special brush, which is mainly used for the construction of corners, behind water pipes and other parts that are not easy to roll coating. During painting construction, it is required that the previous layer of paint be dried before the next layer of paint can be applied, and the time interval between the two layers of painting should be less than 2 ~ 4 hours. Brush coating method: in order to facilitate cleaning after use, first soak the bristles with water or thinner, spin them dry, and then dip them in paint. Don't immerse the bristles in the paint too deeply. After dipping, scrape off the excess paint on the edge of homogenizer or dissolver, and then brush it on the base in sequence. The included angle between the brush and the coated surface is about 50-70 degrees when distributing cloth, and it is reduced to 30-45 degrees when decorating. When painting, the action should be fast, and each painting segment should not be too wide, so as to ensure that the edges are not dry and there will be no seam marks when they are connected with each other; When painted on doors, windows, corners and other parts, in order to avoid sticking, the parts that are not easy to paint should be brushed with a small brush first, and then painted on a large area. This technique is often referred to as "card edge". The width of the card edge is generally 5-8cm. Roller coating adopts manual roller coating, and the tool is a roller made of wool, which is mainly used for coating large-area walls. During construction, dip a little paint on the roller, and then roll it gently and smoothly back and forth on the wall, straight up and down, without twisting and snaking, to ensure the consistency of coating thickness, color and texture. Roller coating method: Before roller coating construction, wet the roller brush with water or thinner, roll off the excess liquid on the waste paper and dip it in paint. When dipping the material, only half of the roller needs to be immersed in the material, and then it rolls on the uniform plate to make the content of the material uniform. Roll coating from top to bottom and then from top to bottom, roll coating on the base layer in a W shape, and then roll coating horizontally and evenly. After the roller is dried, smooth the surface that has just been roller-coated, and the width of each roller coating shall not exceed 4 times the width of the roller. At the same time, it is required to overlap one third of the rollers in the roller coating process to avoid the formation of paint marks at the intersection. In the process of roller coating, the force should be uniform, slightly lighter at first and then gradually increased. In the process of painting, it is required that the speed of the roller should not be too fast to avoid the coating flying test. (3) Painting Skills In order to achieve good painting effect, skilled operation level is necessary. First of all, the requirements for the substrate should be clean, dry and firm, and the coating conditions should be suitable and the dilution ratio should be accurate according to the instructions. Excessive dilution will make the coating uncovered and powdery, and the shiny coating will lose its luster and appear different colors. Secondly, good construction equipment is also necessary. Exterior wall painting sequence should be from top to bottom, from cornice, column top, horizontal top, door and window openings. Each part should be brushed from top to bottom in turn. When drawing each part, you can't give up halfway. If it is necessary to stop, we should also choose the original connection parts of the building structure, such as the connection between the wall and the window frame. This will avoid unsightly seams. When drawing the cornice line, it should be divided into the following two steps: first brush the bottom of the cornice, and then brush the sunny part. When brushing several cornices at the same time, brush along the wall in turn, move quickly during the brushing process, and brush back and forth at the wet-dry joint from time to time to avoid leaving overlap or seams. (4) After the post-treatment construction is completed, the tools should be cleaned immediately, and at the same time, the doors and windows that are accidentally polluted should be cleaned immediately, otherwise the paint will damage the tools, and it is difficult to remove the stains on the doors and windows after drying; The remaining paint should be kept clean and sealed. ⑤ Quality requirements: After painting, it is required that the coating shall be free from coating leakage, powder dropping, peeling, alkali reaction, color biting, uniform color, uniform density, sagging, pimples, brush marks and pollution to doors and windows.