Plastering engineering is divided into general plastering and decorative plastering according to different surface layers, and decorative plastering pays more attention to decorative effect. Except for different surface construction methods, other construction techniques and quality requirements are basically the same as general plastering. General plastering can be divided into ordinary plastering, intermediate plastering and advanced plastering according to operating procedures and quality requirements.
Plastering usually consists of bottom layer, middle layer and surface layer. Ordinary plastering consists of bottom layer and surface layer, and can also be completed at one time without layering, which is suitable for general buildings; Advanced plastering consists of a layer of bottom ash, several layers of intermediate layers and one layer, which is suitable for large public buildings, advanced houses and cold drinks machines.
Plastering shall be carried out at different levels, because it is beneficial to firm plastering, control screeding and ensure quality. If the coating is too thick at one time, it is easy to crack, bulge and fall off due to the different water collection speeds inside and outside. The function of the bottom layer is to make the plastering firmly combine with the base layer and preliminarily smooth it; The function of the middle layer is to smooth the wall, and the surface layer makes the surface smooth and meticulous, which plays a decorative role. The plastering thickness of each layer is generally 5-7mm for cement mortar and 7-9mm for lime mortar or mixed mortar. When the surface layer is made of paper reinforced ash and gypsum ash, the thickness after leveling and compaction shall not be greater than 2mm. The total thickness of plastering should also be controlled. Too thick will easily cause shrinkage cracks. Generally, the interior wall is not more than 18mm, and the exterior wall is not more than 20 mm. Because the ceiling plastering is in a suspended state, it requires higher cohesive force, and the thickness should be controlled within 15 mm.
4. Construction preparation
(1) Material preparation. For the materials used in plastering engineering, most design drawings and standard atlas have clear requirements, and some need to be customized on site. The location of materials should consider the requirements of location and function, for example, the external wall is open-air and requires certain waterproof performance. It is best to choose cement mortar or mixed mortar instead of lime mortar; Skirting board, dado, foot wrap, etc. , often wet or easy to collide, waterproof and firm, it is best to use cement mortar. Plastering sand is preferably medium sand or a mixture of coarse sand and medium sand, and the sand should be screened before use. Lime plaster shall be white and delicate, and shall not contain immature particles. The texture of the surface material should be fine and uniform.
(2) Machine preparation. In addition to the mortar machine, vertical transportation, scaffolding and other construction conditions, plastering engineering should also prepare team operating tools and quality inspection tools. There are many operating tools for plastering, such as wood plastering, iron plastering, internal plastering and external plastering. Because plastering, as the content of decoration project, requires higher details such as the angle of yin and yang, so many tools are used for detailed structure. The quality inspection tools for plastering are similar to those used in wall-building projects, including bracing plates, guiding feet, feelers, square feet and small hammers.
(3) Preparation for acceptance. The acceptance of organizational structure before plastering is the requirement of construction quality management procedure, which is equivalent to the acceptance of concealed works. Mainly check whether the water and electricity pipelines and distribution boxes are installed, whether the door and window frames are completely installed, whether the elevation is accurate, and whether there are any omissions in the buried wooden bricks or iron pieces.
3. Basic treatment
The function of basic treatment is mainly to improve the cohesive force between plastering layer and basic layer and prevent plastering layer from hollowing out. The content of base treatment includes: removing dust and dirt from the surface of brick walls, concrete and other bases, chiseling off the smooth concrete surface or brushing a layer of pure cement slurry or interfacial agent on the wall surface to increase the cohesive force. There are too many uneven places in the wall, which should be chiseled away or filled with mortar in advance. The gap between the door and window frame and the wall should be filled with mortar, and the toe of the wall, the hole through the wall of the pipe, the groove left by digging the wall and installing the pipe should be blocked with cement mortar. Where the wall meets the concrete, cracks are easy to appear after painting because of the temperature change at the grass-roots level and the different thermal expansion and contraction. It is required to lay steel mesh, and the lap width shall not be less than100 mm. Before plastering the precast concrete ceiling, fine stone concrete shall be filled in the slab joints. Water the wall before plastering, and the humidity should be appropriate, which is the same as watering the brick before building a wall.
4. Procedures and requirements
(1) Wall plastering: Take the advanced plastering of the interior wall of the room as an example. The main working procedures are: finding the corner of yin and yang, erecting the standard bar of ash cake, protecting the corner, leveling in layers, trimming and surface calendering.
For rooms with square floor tiles on the ground, it is particularly important to find the corner of yin and yang. For a small room, you can use a wall as the baseline and square it with a square ruler. For example, if the room area is large, the reticle will be popped up on the ground as the corner plastering line. When it is about 10cm away from the corner, hang it straight with a hammer, play a vertical line on the wall, and then play the line inward according to the reticle and the flatness of the wall, pop up the corner plastering line, pop up the dado or skirting board line.
Ash cake is used to control the thickness of plastering layer. First, check the flatness and verticality of the wall with a pallet, roughly determine the thickness of the plastering layer (the thinnest part is not less than 7mm), and then make a standard gray cake with a size of 5cm square on the upper corner of the wall according to the thickness, and then lift the two gray cakes vertically with a line hammer, and make two standard gray cakes at the lower corner of the wall (high and low positions are generally catchy at the skirting line). Then tie a small thread with nails in the gap near the left and right ash cakes, and add several standard ash cakes every 1.2- 1.5m according to the thread. After the tip of the ash cake is dry, the mortar screed with a width of about 10cm shall be spread between the upper and lower ash cakes, and it shall be leveled with a wooden scraper as the standard for plastering the bottom ash. Before plastering, the external corners of indoor walls, cylinders, doors and windows should be protected with corner protectors, because these places are most likely to be damaged by collision, so there are special requirements for strength. If there is no provision in the design, the corner protector can be plastered with 1:2 cement mortar, with a height of not less than 2m and a width of not less than 50mm on each side. The method is: plaster according to the thickness of the ash cake, then stick a figure-eight guide rule and try to hang it straight.
After the mortar screed-coat is slightly dry, it should be primed. If the leveling layer is dry, it will appear higher than the wall due to the shrinkage of the mortar on the wall. Use a wood trowel to lean the bottom ash edge against the screed on both sides, smooth it from bottom to top, and then smooth it with a wood trowel. After the primer is dried by 50% to 60%, it is polished. After calendering, in order to make the wall smooth, you can brush it in the same direction with a brush pen dipped in water.
When cement mortar surface is used in toilet and kitchen, the surface of base ash must be painted or scraped flat, the surface should be smooth and smooth, and the surface should be calendered not less than twice, and the surface should be sprayed with water the next day.
In the process of plastering, if the skirting board should be straight, use the guiding rule to rely on the line, use the iron trowel to cut, trim and clean it up.
External windowsill, lintel, awning, balcony, roof, etc. A running water edge shall be provided above and a drip line or drip tank shall be provided below. The depth and width of the drip tank should not be less than 10mm, and should be neat and consistent. The drip tank generally adopts aluminum alloy or plastic "U"-shaped strip, which is more beautiful.
(2) ceiling plastering
Because the ceiling is far away from people's field of vision, the smoothness and smoothness of plastering are generally lower than the requirements of walls, and ash cakes are generally not required. Its construction method is to pop up a horizontal line on the wall near the ceiling as the basis for plastering and leveling the ceiling. Then start from the corner of the ceiling, along the ceiling, and level the surroundings. In order to avoid falling ash, the first layer of ash should generally be smeared thin. After wiping the base ash, then wipe the leveling layer, level it with a ruler, and rub it flat with a wooden trowel. When the leveling layer is sixty to seventy percent dry, it should be covered; After the cover ash is slightly flat, it shall be compacted and polished with an iron trowel, and the surface shall be smooth. Outdoor barbecue should be smooth and free of scratches and bubbles. The internal angle at the intersection of ceiling and wall should be straight and clear.