General knowledge of coating: quality control measures for coating construction of building exterior wall

Core tip: in recent years, the exterior wall coating has been widely recognized and applied in the exterior wall decoration of buildings due to its rich color, low cost, simple construction and good decoration and protection effect on buildings Meanwhile, the quality requirements of the exterior wall coating project have been continuously improved, At present, the quality of many exterior wall coating projects is not up to the standard, so the construction company has the responsibility to improve the quality control technology of exterior wall coating projects, and to explore and study it In this paper, the quality control measures of exterior wall coating are described by taking the housing renovation project of Taiyuan Xiugan Institute of Beijing Military Region as an example Housing renovation project of Taiyuan Xiugan Institute of Beijing Military Region Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Home of coatings news: recent external walls Due to its rich color, low cost, simple construction and good decoration and protection effect on buildings, the coating has been widely recognized and applied in the decoration of the outer wall of buildings At the same time, the quality requirements of the outer wall coating project have been continuously improved At present, the quality of many outer wall coating projects is not up to standard, so the construction unit has the responsibility to improve the quality control technology of the outer wall coating project To explore and study it In this paper, the quality control measures of exterior wall coating are described by taking the housing renovation project of Taiyuan Xiugan Institute of Beijing Military Region as an example The housing reconstruction project of Taiyuan rest and dry Institute of Beijing military region is a housing project built by Beijing Military Region for retired cadres to improve their quality of life It covers an area of 32 mu, four 30 story high-rise buildings, with a building area of 117264m2 The outer wall is designed with 80mm thick extruded insulation board, pasted with mortar, anchored with insulation nails, hung with glass fiber mesh cloth, plastered with anti crack mortar and waterproof putty for the outer wall Priming and leveling for 2 times, primer for 1 time and finish for 2 times 1 purpose of quality control of exterior wall coating engineering In the past, it was generally believed that the quality of exterior wall coating works was determined by the quality of exterior wall coating products However, through the solid verification, we found that even if the same quality of exterior wall coating is used on the same type of building exterior wall, if the construction technology level is uneven, the quality of exterior wall coating works also has great difference, which shows that the quality of exterior wall coating works is not only It is determined by the quality of exterior wall coating products, and also has a direct relationship with coating construction technology In order to ensure that the quality of the exterior wall coating project meets the relevant standards, the construction technology level should be improved while selecting the qualified exterior wall coating products, which complement each other and are indispensable Therefore, in order to ensure the satisfactory acceptance results and long-term decoration effect, the quality control of the exterior wall coating project must be strictly implemented The quality control of exterior wall coating engineering is a step-by-step process, including materials, design, construction and many other aspects 2.1 the selection and quality control of materials The main types of exterior wall coatings include solvent based thin wall coatings, emulsion type thin wall exterior coatings, emulsion type elastic exterior wall coatings, emulsion molding sand wall exterior wall coatings and complex exterior wall coatings According to the use requirements of the area and the building type, select the appropriate coating variety Many factors need to be considered in the actual selection of exterior wall coatings, such as stain resistance index, estimated service life and artificial aging index This project uses emulsion type thin wall exterior paint according to design and owner requirements Due to the different colors of the same kind of exterior wall coating, the weatherability of the coating is also different, so this factor should be fully considered when choosing the pigment In addition, it is necessary to ensure that the materials selected in the exterior wall coating project are compatible with the performance of the exterior wall base and the exterior wall coating The project department requires the coating supplier to provide matching putty materials according to the actual situation of the site project In view of the present situation of the paint market, when choosing the paint, we must choose the merchants with good reputation and big brand We can carry out the material inspection from the following points: ① the effect of opening the pot: the effect of opening the pot of high-quality paint is good, without mildew, rust, starch and water ② Construction effect: there is no brush mark or roller mark, the unit painting area is large, the covering power is good, and the construction effect is good The covering power refers to the minimum amount of paint evenly applied on the wall surface to ensure that its background color is no longer present, expressed in grams per square meter The smaller the value is, the smaller the unit area is China's original national standard is 250G / m2, and the value of skyscraper coating used on site is 220-230g / m2 ③ Coating: the qualified coating shall not lose powder, even if it is dirty, it can be scrubbed with water, which undoubtedly puts forward high requirements for the washability of the coating The relevant national standards require that the first-class products shall be able to wash more than 300 times, and the qualified products shall be able to wash more than 100 times But at present, the paint quality in the market is seriously uneven Some paint products can be washed for more than 2000 times without any change, while some paint products have been damaged only after washed for several times Special attention should be paid to the selection The field test data of skyscraper paint selected for the project is 295-320 times ④ Choose famous brand products: try to choose products with good brands Among similar products, it is better to choose products with national environmental protection marks Because those enterprises with good brands usually have the characteristics of large scale, high output and strict management, which can effectively guarantee the product quality, the project department selects the big brands that the state can trust ⑤ Trademark check: the important marks and data related to the product shall be displayed on the packaging barrel of latex coating, such as trademark, production date, weight, etc., and the actual data can also be queried according to the Internet information on the barrel 2.2 design quality control of exterior wall coating engineering ① the characteristics of exterior wall coating engineering shall be fully considered in the design of facade of exterior wall, specifically: first, the quality requirements of the base layer of exterior wall must meet the requirements of exterior wall coating to avoid cracks to the greatest extent; second, corresponding measures shall be formulated for the walls designated to use coating to adapt to the characteristics of architectural coating ② In addition to the above factors, the construction environment is also an essential factor in the selection of exterior wall coating products For example, when the temperature is below 5 C, it is better not to use emulsion type exterior wall paint, because the coating is difficult to form film at low temperature The exterior wall coating construction of our project department is actually in August and September, and also considering the temperature factor 2.3 construction process quality control 2.3.1 quality pre inspection before the construction of exterior wall coating works, the project department shall strictly inspect the construction quality of the sticking of heat preservation board and plastering of anti crack yarn slurry, and carefully check the type and color of the coating entering the site The following points must be done before the formal construction: ① ensure that all preparations before the construction are ready, such as cornice, the bottom of the window panel according to the technical standards to complete the construction measures of the drip line ② Ensure that the insulation board and anti crack yarn pulp have passed the quality acceptance ③ By checking the moisture content and pH value of the base course of the plastering surface, it is determined whether the construction should be carried out formally The specific standard is that the moisture content is less than 10%, and the pH value of the base course is more than 10 At room temperature, the above indexes can be achieved in the anti cracking layer for more than 7 days ④ Review the type, specification, color and coating engineering grade of the putty, primer and surface coating products according to the design requirements ⑤ Before the formal construction, relevant personnel shall be arranged to make a "sample" according to the predetermined construction process requirements, which shall be accepted by the supervisor and the owner, and large-scale construction can be carried out only after it is qualified 2.3.2 the quality control of the construction process must strictly control each process in the construction process Taking the project as an example, the general construction process is shown in Figure 1 For each process, the quality control is as follows: ① wall cleaning Check the flatness of the base course to ensure that it conforms to the relevant specifications and standards, and lay a good foundation for pasting the insulation board ② Stick insulation board 1) Check the flatness of the base course surface, and there shall be no garbage, oil, floating ash and other dirt on the surface; 2) when pasting the insulation board, use the frame bonding method, the bonding area is more than 40%, the joint is compact and flat, no through joint is allowed, and the number and position of the insulation nails shall be set in strict accordance with the requirements ③ Hang net and plaster anti crack mortar The thickness of the first anti crack yarn slurry is 2-3mm, then hang the net, press the net into the mortar, and then apply the second anti crack yarn slurry, the thickness is 3-4mm, and the plaster surface shall be even and flat ④ Grind and compact 1) The putty with a certain strength shall be polished with sandpaper; 2) the cleanliness of the base surface shall be ensured ⑤ Apply primer 1) Ensure the construction quality, and put an end to peeling, micro cracking, missing brush and other phenomena; 2) ensure the coating is dry, only in this way can the next link of construction be carried out ⑥ Apply the first coat 1) Check the construction quality, and there shall be no missing brush, sagging, pimple, brush pattern, etc 2) test the degree of dryness of the coating When applying emulsion type coating, the coating should be dried before proceeding to the next process ⑦ Apply the second coat (i.e final quality acceptance project) Check the construction quality, put an end to peeling, micro cracking, missing brush and other phenomena, ensure that the construction quality meets the relevant specifications and standards, in addition, it is required to have the same color and clean doors and windows At the same time, for the high-grade exterior wall coating project, in addition to meeting the above requirements, it is also required that there is no sand hole, no brush pattern, the color separation line is straight, and the deviation is not more than 1mm 3 quality defects and quality pre control of exterior wall coating engineering through analysis of the exterior wall coating engineering, we found that once there are quality problems of exterior wall coating engineering, such as peeling, missing brush, sagging, etc., it needs to consume a lot of human and financial resources to repair it, resulting in a great waste of resources In order to ensure that the exterior wall coating project can be accepted, and can be beautiful for a long time, the effect of post control is very little, the best way is to use the method of quality pre control The following are the corresponding pre control methods for different exterior wall coating engineering problems: 3.1 falling off means that there is no adhesion between the coating and the base, resulting in the falling off of small or whole film Pre control method: first, the base surface must be clean before construction; then, the base surface shall be dry and free from mildew; during the painting process, the thickness of the painting layer shall be strictly controlled; the moisture content and pH value of the base shall be strictly controlled; putty and primer with good adhesion to the base shall be selected 3.2 powder removal refers to the easy powder removal of dry coating Pre control method: it is necessary to ensure that the base is dry The moisture content of the emulsion coating must be less than 10% It is best to construct at the condition of above 10 C; the age of the base material must comply with the relevant standards and standards; before the application, the coating should be evenly stirred and water or solvent should not be used to dilute the coating 3.3 efflorescence refers to the phenomenon that the surface coating of concrete and plastering reveals white alkaline substance, forming uneven surface color Pre control method: control concrete and plastering