Construction quality control measures for exterior

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Quality control measures for coating construction of building exterior walls

quality control measures for coating construction of building exterior walls

March 6, 2019

0 Introduction in recent years, exterior wall coatings have been widely recognized and applied in the decoration of building exterior walls because of their rich colors, low cost, simple construction, good decoration and protection of buildings and other characteristics. At the same time, the quality requirements of exterior wall coating engineering have also been continuously improved, At this stage, the quality of many exterior wall coating projects is not up to standard, so the construction unit has improved the quality control technology of exterior wall coating projects, and discussed and studied it. This paper takes the housing reconstruction project of Taiyuan retired office of Beijing Military Region as an example to elaborate the quality control measures of exterior wall coating

the housing renovation project of Taiyuan retired cadre Office of Beijing military region is a housing project built by the Beijing Military Region to improve the quality of life of retired cadres. It covers an area of 32 mu, and consists of 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 temperature nails, hung with glass fiber grid cloth, plastered with crack resistant mortar, primed and leveled with waterproof putty on the outer wall twice, primed once, and painted twice with Chinese paint

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1 purpose of quality control of exterior wall coating engineering in the past, it was generally believed that the quality of exterior wall coating engineering was determined by the quality of exterior wall coating products. However, after physical verification, we found that even if the same quality of exterior wall coating materials were used on the exterior walls of the same type of buildings, if the construction technology level was uneven, the quality of exterior wall coating engineering was also quite different, This shows that the quality of exterior wall coating engineering is not only determined by the quality of exterior wall coating products, but also has a direct relationship with coating construction technology. In order to ensure that the quality of exterior wall coating engineering meets the relevant specifications and standards, while selecting qualified exterior wall coating products, we should also improve the construction technology level. The two complement each other and are indispensable. Therefore, in order to ensure satisfactory acceptance results and long-term decorative effects, we must strictly implement quality control of exterior wall coating engineering

2 content of quality management and control of exterior wall coating engineering quality control of exterior wall coating engineering is a step-by-step process, including materials, design, construction and many other aspects

2.1 material selection and quality control

the main types of exterior wall coatings include solvent based thin exterior wall coatings, lotion thin exterior wall coatings, lotion elastic exterior wall coatings, lotion sand exterior wall coatings and multilayer exterior wall coatings. According to the use requirements of the area and the type of building, select the appropriate coating varieties. Many factors need to be considered in the actual selection of exterior wall coating, such as stain resistance index, estimated service life, artificial aging resistance index, etc. lotion thin exterior wall coating is used in this project according to the design and the owner's requirements. Because the weather resistance of the same kind of exterior wall paint is also different according to the color, this factor should be fully considered when selecting pigments. 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 exterior wall coating. The project department requires the coating supplier to provide supporting putty materials according to the actual situation of the on-site project

in view of the current situation of the paint market, when choosing paint, we must choose merchants with good reputation and big brands. We can carry out material inspection from the following points:

① can opening effect: high quality paint has good can opening effect, without mildew, rust, starch and water separation

② construction effect: there are no brush marks and roll marks, 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 painted on the wall surface to ensure that its background color is no longer present, expressed in grams/square meters. The smaller the value, the smaller the amount per unit area. The original national standard of our country is 250g/m2, and the Ferris paint used on site is 220~230g/m2

③ coating film: qualified coating film should not lose powder. Even if it is dirty, it can be wiped with water, which undoubtedly puts forward high requirements for the washability of the coating film. Relevant national specifications and standards require that first-class products should be able to be washed more than 300 times, and qualified products should be able to be washed more than 100 times. However, at present, the phenomenon of uneven coating quality in the market is serious. Some coating products can be washed for more than 2000 times with almost no change, while some coating products have been damaged after only washing for several times. Special attention should be paid to the selection. The field test data of Ferris coating 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 best to choose products with national environmental protection marks. Since those enterprises with good brands usually have the characteristics of large scale, high output and strict management, which can effectively ensure the product quality of domestic cobalt related listed companies driven by the rise of cobalt price, the project department selects large brands that the country can trust

⑤ check the trademark: the important marks and data related to the product should be displayed on the packaging barrel of latex paint, such as the trademark, production date, weight, etc., and the actual data can also be queried according to the interconnection information on the barrel

2.2 quality control of exterior wall coating engineering design

① the characteristics of exterior wall coating engineering should be fully considered in the design of exterior wall facade, specifically: first, the quality requirements of exterior wall base must meet the requirements of exterior wall coating to avoid cracks to the greatest extent; Second, corresponding measures should be formulated for the walls designated to use paint to adapt to the characteristics of architectural paint

② when selecting exterior wall coating products in the design, in addition to the above factors, the construction environmental conditions are also an essential consideration. For example, when the temperature is lower than 5 ℃, it is best not to use lotion exterior wall paint, because it is difficult to form a film at low temperature. The exterior wall coating construction of our project department was carried out in August and September, and the temperature factor was also taken into account

2.3 quality control in the construction process

2.3.1 quality pre inspection

before the construction of exterior wall coating engineering, the project department shall strictly inspect the construction quality of the pasting of insulation board and the application of anti cracking yarn slurry, and carefully check the variety and color of the paint entering the site

the following points must be done well before the formal construction:

① ensure that all preparations before the construction are ready, such as the construction measures of drip line at the cornice and the bottom of the window panel according to the technical standards

② ensure that the insulation board and anti crack yarn pulp have passed the quality acceptance

③ determine whether the construction should be formally carried out by checking the moisture content and pH value of the plastered surface base. The specific standard is that the moisture content is less than 10%, and the pH value of the base is more than 10. The anti crack yarn sizing layer can reach the above indicators at room temperature for more than 7 days

④ recheck the variety, specification, color and coating engineering grade of the repair putty, primer and surface coating products according to the design requirements

⑤ before formal construction, relevant personnel should be arranged to make a "template" according to the requirements of the scheduled construction process, which should be accepted by the supervisor and the owner. Large scale construction can be carried out only after it is qualified

2.3.2 quality control of construction process

every process in the construction process must be strictly controlled. Take this project as an example, because the deposition strength of the surface of laser deposited parts becomes uniform, the general construction process is shown in Figure 1

construction process drawing of building exterior wall coating

for each process, the quality control is as follows:

① wall cleaning

check the flatness of the base course to ensure that it meets the relevant specifications and standards, and lay a good foundation for sticking insulation boards

② stick insulation board

1) check the flatness of the base surface, and the surface shall be free of garbage, oil, floating ash and other dirt; 2) When pasting the insulation board, the frame bonding method is used. The bonding is usually also known as the boundary lubrication area is greater than 40%. The joints are compact and flat. Through joints are strictly prohibited. The number and position of insulation nails are set in strict accordance with the requirements

③ hang and plaster anti crack mortar

the thickness of the first coat of anti crack yarn paste is 2~3mm, then hang it, press it into the mortar, and then apply the second coat of anti crack yarn paste, the thickness is 3~4mm, and the plastering should be uniform and flat

④ flatten and compact

1) scrape the bottom putty with a certain strength and polish it with sandpaper; 2) The cleanliness of the base surface shall be ensured

⑤ apply primer

1) ensure the construction quality and eliminate peeling, micro cracking, missing brushing and other phenomena; 2) Ensure that the coating is dry, and only in this way can the construction of the next link be carried out

⑥ brush the first coat of paint

1) check the construction quality, and there shall be no missing brushing, falling, bumps, brush lines and other phenomena. 2) Check the dryness of the coating. When applying lotion coating, the coating should be dry before the next process

⑦ brush the second coat of surface paint (i.e. the final quality acceptance project)

check the construction quality, put an end to peeling, micro cracking, missing painting and other phenomena, and ensure that the construction quality meets the relevant specifications and standards. In addition, it is also required to have consistent colors and clean doors and windows. At the same time, for advanced exterior wall coating engineering, in addition to meeting the above requirements, it is also required to have no sand holes, no brush lines, straight color separation lines, and the deviation is not greater than 1mm

3 quality defects and quality pre control of exterior wall coating engineering through the analysis of this exterior wall coating engineering, we found that once there are quality problems of exterior wall coating engineering, such as peeling, missing brushing, falling, etc., it needs to consume a lot of human and financial resources to repair it, resulting in a great waste of resources. The best way to ensure that the exterior wall coating project can pass the acceptance and be beautiful for a long time is to adopt 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

refers to the lack of adhesion between the film and the base, resulting in the falling off of small pieces or the whole film

pre control method: first, the surface of the base must be clean before construction; Then ensure that the surface of the base course is dry and free of mildew and stains; The thickness of the coating layer shall be strictly controlled during the coating process; Strictly control the moisture content and pH value of the base; Putty and primer with good adhesion to the base shall be selected

3.2 powder dropping

refers to that the dried coating is easy to drop powder

pre control method: it is necessary to ensure that the base course is dry, and the moisture content of the lotion coating must be less than 10%; It is better to construct under the condition of above 10 ℃; The age of base material must comply with relevant specifications and standards; The paint shall be stirred evenly before application, and it is forbidden to dilute the paint with water or solvent

3.3 efflorescence

refers to the phenomenon that the surface coating of concrete and plaster reveals white alkaline substances, forming uneven surface color

pre control method: control the water content of concrete and plastering surface. The water content of lotion coating must be less than 10%, and the pH value should be below 10; The surface coating with good alkali resistance shall be adopted

3.4 missing coating and bottom penetration

refers to that the color of the coating surface is obviously uneven and there is bottom exposure

pre control method: when reviewing the coating, pay attention to whether its coverage is qualified; Operate in strict accordance with the construction process to avoid missed coating

3.5 brush marks

refer to the brush marks left on the surface of the coating film

pre control method: firstly, paint varieties with good leveling performance and paint brushes with appropriate specifications should be selected; On this basis, ensure that the painting technology meets the relevant specifications

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