Quality control in the construction of exterior wa

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Quality control in the construction of building exterior wall coating

Quality Control in the construction of building exterior wall coating

December 1, 2018

0 Introduction with the development of social economy, building exterior wall decoration has become an indispensable process. Among many building exterior wall decoration materials, coatings are widely used in building exterior wall decoration because of their advantages such as short construction period, high work efficiency, low price, light weight, convenient maintenance and so on. The decorative quality of building exterior wall paint directly affects the overall image and use function of the building. In order to control the quality of exterior wall paint construction, we can start with the following aspects of Chinese paint

1 design is the foundation of construction. As the saying goes, "if the foundation is not firm, the earth will shake", so design is particularly important. The external wall of the building is in direct contact with the external environment, and the temperature fluctuates greatly. If the separation area of the facade is large in the design, the external wall is prone to cracks when it expands and contracts under the influence of temperature. Therefore, the separation area of the facade should be as small as possible, preferably 3 ~ 5 m2. Moreover, there are many kinds of coatings, and their performance and use requirements are different. Only when the designer understands the performance of various coatings, and fully considers the factors such as the base course attached to the coating, the use position of the coating, and the natural environment in which the coating will be located in the future, can he choose a suitable coating

2 the outer wall plastering of the base course is the base course attached by the paint, and the cracking of the plastering is the main reason for the cracks in the paint. The plastered base course of the outer wall can also protect the building from the erosion of harmful media such as wind, rain, snow and atmosphere, and improve the durability of building components. The quality of plastered base course can be controlled through the following aspects

2.1 raw materials

there are many cement manufacturers, and the product quality is mixed. The author has encountered the situation of wall plastering hollowing and falling off and rework due to the use of cheap small factory cement. If the stability of cement is not good, second, when the cement hardens, it will crack due to uneven volume expansion. If the cement is stored for a long time or affected with moisture, the strength of the plastering layer will not go up

therefore, cement must be submitted for inspection. Generally, the storage period should not exceed 3 months. Cement stored for more than 6 months must be inspected before use. Cement of different varieties shall not be mixed. Sand is a local material, and the situation of sand produced in different places is different, but generally speaking, medium sand with good grading should be used. The sand grain should be hard and clean, and grass roots, clay, alkali and other harmful substances should not be too much. Before use, use sieves with different apertures according to different requirements. Lime can improve the workability of mortar, but the uncured lime will continue to mature in the mortar, causing cracks in the plastering layer due to volume expansion. Therefore, the lime used must be fully matured into lime paste

2.2 construction

the wall surface is not cleaned before plastering, the wall surface is too dry, and the local wall surface is smooth, which often leads to poor adhesion between the plastering and the base course, and is easy to bulge or fall off. Therefore, before plastering, the wall should be cleaned, the holes should be blocked, and the concrete with bulge film protruding from the wall should be chiseled flat. The concrete with pitted surface and honeycomb defects should be treated in advance. Unused holes such as scaffold holes shall be filled in advance and leveled with 1:2 cement mortar in layers

the wall should be fully watered. If it is a concrete wall, it should also be treated with slurry throwing, chiseling, etc. to increase the net profit close to the "waist cut" the combination of plastering and wall. The mix proportion of mortar is an important indicator of mortar quality control. If it is not strictly followed, it will seriously affect the strength and quality of mortar. At the construction site, workers often add water at will for the convenience of plastering construction. In this way, not only the strength of mortar is not enough, but also the excess water will shrink and cause cracks after evaporation. Therefore, it is necessary to measure accurately according to the mortar mix proportion and control the mix proportion. The mortar should not be mixed too much at one time, but should be used as soon as it is mixed. The cement mortar must be used within 3 ~ 4 hours after mixing. The mortar that exceeds the time must not be mixed again

plastering is usually divided into two or three layers. The function of the bottom layer is that the mortar can bond firmly with the wall, so it is required that the mortar should have good workability and strength. The main function of the middle layer is to trowel, sometimes it can not be done. The surface course shall be flat and smooth. The thickness of each layer shall be controlled at about 7 mm and compacted in layers. If plastered too thick, it is not easy to compact, and shrinkage cracks will also occur. Each layer shall be cured after construction, and the plastering construction of the next layer can be carried out only after the plastering layer is fully condensed. Because heat will be generated when the mortar solidifies, each layer of plastering is too tight, and the later layer of plastering affects the heat release of the previous layer of plastering, resulting in stress between each other, resulting in cracks in the plastering layer

before each layer, check whether there is local hollowing in the previous layer. If there is, cut the hollowing with a cutting machine until there is no hollowing at the edge. Each side of the hollowing edge extends at least 5 cm. The hollowing incision is processed into a notch with a drill rod, and then leveled by layers with mortar of the same grade. Flatness is an important index that should be controlled for surface plastering. Generally, it is required to check with a 2 m vertical ruler. The verticality of the facade and the surface flatness should be less than 3 mm. The dividing strip should be embedded in advance and cannot be slotted after plastering. The flatness of the separator strip shall be controlled within 5 m, and the length error shall be within 3mm

in the construction process, pay attention to the timely maintenance of plastering. Before setting, each plastering layer should be prevented from exposure, rapid drying, water washing, impact and vibration, so as to ensure that its ash layer has sufficient strength. As long as the mortar ratio is reasonable and strict construction, cracking can be completely avoided

3 exterior wall coating construction 3.1 construction preparation

the coating construction can only be carried out after the base course is fully cured and reaches the corresponding indicators. If the moisture content is too high, the alkali seepage of the wall surface, peeling and falling off of the coating and even mildew can be caused after the coating construction. Affect the overall image of the building, and even rework it seriously. After a period of maintenance, the surface of the base course often has attachments such as soil, dust, oil, etc., so cleaning is an essential process. Neutral detergent can clean grease, dirt, dust, etc. can be washed with high-pressure water, or can be cleaned with brooms, brushes, etc

problems such as lack of edges and corners caused by poor protection of finished products can be repaired with cement mortar. Smaller cracks can be directly repaired with putty, and larger cracks can be chiseled into a "V" shape and repaired with cement mortar. In case of old building maintenance, if the old coating is intact, it can be painted directly after cleaning the surface; In case of peeling and Chalking of the old coating, the old coating must be removed and re painted with one primer and two finishing coats

3.2 raw materials

putty used in coating engineering plays a connecting role. The paint film is connected with the base by putty as an intermediary material. As the ancients said, "if the skin doesn't exist, how can the hair be attached?". Paint film and putty are just like the relationship between hair and skin; Without skin, hair naturally loses its basis for existence; Without putty, the paint film also loses the prerequisite for adhesion to the substrate

in addition, putty can also fill matrix defects, level and reduce paint consumption

the putty requires good bonding strength, so as to ensure that the putty layer does not bulge, explode and peel off, and also maintain a good bonding force with the coating layer to ensure that the surface coating does not peel off. Putty with water resistance must be used for exterior wall painting, and interior wall putty cannot be used for exterior wall construction. If the putty used in the construction of external walls has poor bonding strength, alkali resistance, water resistance and other properties, it often fails to play the connecting role that the putty should play, resulting in quality problems such as falling off and cracking of the coating layer. If necessary, the supporting putty provided by the paint manufacturer can be used. After the putty is dry, it should be polished smooth and cleaned

the coating directly contacts the external natural environment, improves its appearance value through the beautification of the building, including color, pattern, gloss, three-dimensional pattern and conceptual design, and can also protect the building from the direct impact and damage of the environment, such as mold resistance, scrub resistance, waterproof, etc. Since the dead fish has reached more than a thousand kilograms, the quality of this paint itself is the key to the quality of exterior wall decoration

architectural coatings are mainly composed of base materials (also known as main film-forming substances and adhesives), pigments and fillers, solvents or water, and various supporting additives. According to the main film-forming substances, it can be divided into three types: organic coatings, inorganic coatings and composite coatings. For architectural coatings, products produced by regular manufacturers with product quality certification or green environmental protection products should be preferred. To prevent the use of fake and inferior products, carefully check whether the variety, performance and color of the incoming materials meet the design requirements, and check whether the certificate of conformity and test report are complete and consistent with the incoming materials. A special person is responsible for the incoming materials, and mark and store them according to different varieties, performance and colors, so as to avoid the confusion and misuse of similar coatings

3.3 construction factors

the exterior wall coating should follow the principle of first up and then down, from the roof, gutter, column top, beam and rafter to the order of walls, doors, windows and baseplates. Each part shall also be painted from top to bottom. To achieve good coating effect, skilled operation level is necessary. During the painting process, it is not allowed to stop at will. If it is necessary to stop, it must be selected at the junction of the separator strip or component, so as to avoid obvious handover marks

viscosity is an important indicator of paint brushing, which should be strictly controlled. Excessive dilution will make the paint not cover the bottom and powdered, and glossy paint will lose light and have different colors. The operation shall be carried out according to the requirements of the instruction manual, and the dilution ratio shall be accurate. The paint shall be stirred evenly before use, and no color or water shall be added arbitrarily. It shall be used within the specified time, otherwise the coating quality will be affected. When using the multi-component coating, it should be strictly controlled according to the instructions, mixed in batches, and used in time. The construction by times cannot be followed too closely, and the next construction can be carried out only after the surface is dry

each coat should be applied evenly, and the thickness should not be too thick. The coating has high requirements for the construction environment. When working in an outdoor environment, the temperature and humidity change greatly, and rain, fog and other weather may also be encountered. This requires the construction management personnel to strengthen their minds, accumulate construction experience, and understand the weather conditions before construction to avoid. 80% is the most suitable relative humidity for the coating. Construction can be carried out when the temperature is 10 ~ 35 ℃. Direct sunlight shall be avoided during construction, and exposure shall not be allowed during transportation and storage

with the progress of science and technology, coatings will continue to develop new products, and the performance and construction requirements of different products will be different. The construction personnel should strengthen the study of new products and carry out the construction according to the requirements of different coatings. They should not carry out the construction subjectively based on previous construction experience

4 conclusion at present, different kinds of coatings have different requirements and uses. Therefore, the construction personnel should have a certain knowledge of building materials and have a good grasp of the performance and scope of application of the coating. If the coating is inadvertently used during construction, it will not only increase the construction cost, but also cause the trouble of rework and delay the construction period

in short, as long as the architectural design is reasonable, the processing technology and zero cover valve port construction are properly organized, and the construction scheme of "safety first and quality-oriented" is resolutely implemented to ensure good progress

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