Common knowledge of coating: how to avoid cracks of external wall putty

Core tip: polymer dry mixed plastering mortar and external wall putty play an important role in building external wall decoration The cracking of external wall putty is the most headache for many real estate developers, construction engineering companies, decoration personnel, property management and maintenance personnel, and building materials manufacturers The reasons for the formation of cracks in the outer wall are relatively complex It is necessary to master the performance of relevant materials, construction technology, the relationship between materials and technical principles, and select and use materials scientifically to ensure product quality and project construction quality 1、 Advantages of polymer dry mixed plastering mortar and external wall putty Polymer dry mixed plastering Shenyang steel structure fireproof coating construction expert punde Building Fire Engineering Co., Ltd Recommended introduction: since its establishment, Shenyang punde Construction Fire Engineering Co., Ltd has cultivated a group of professional construction teams with excellent equipment, rich experience and serious responsibility with advanced and scientific management methods and strict engineering quality assurance and after-sales service system It has undertaken a number of fire system installation projects, which has been praised by customers Every idea and special requirement of you will be fully considered by us and fully realized in the construction technology, which will become the cornerstone of our successful long-term development We are looking forward to your invitation, to provide you with quality services and high-quality technical support! All construction coatings have passed ISO9001 Paint Home News: polymer dry mixed plastering mortar and external wall putty play an important role in building external wall decoration The cracking of external wall putty is the most headache for many real estate developers, construction engineering companies, decoration personnel, property management and maintenance personnel, and building materials manufacturers The reasons for the formation of cracks in the outer wall are relatively complex It is necessary to master the performance of relevant materials, construction technology, the relationship between materials and technical principles, and select and use materials scientifically to ensure product quality and project construction quality 1、 Advantages of polymer dry mixed plastering mortar and exterior wall putty polymer dry mixed plastering mortar and exterior wall putty are widely used in exterior wall decoration engineering They have the following advantages: 1 Excellent quality They adopt specialized and standardized production in factories, with stable and reliable quality It avoids the quality problems caused by the blind self purchase of materials and the random deployment of construction personnel 2 Fast construction It can be used by mixing with water The product has good workability, strong water retention, no sagging and easy adhesion, which can improve work efficiency and reduce the labor intensity of construction personnel 3 High bond strength Due to the full function of polymer in the product, it can promote the cement to be fully hydrated, improve the ability of cement mortar to make full use of natural conditions to realize self maintenance, increase the later strength and stability of cement, control and prevent the occurrence of cracks, hollows and falling off caused by dry shrinkage 4 Green environmental protection The product does not contain volatile and harmful substances, and is harmless to the environment and human body It is a green ecological building material product 2、 The main causes of cracks in plastering mortar and external wall putty are cracks and cracks in cement-based mortar and putty, which is a universal problem After years of research and practice, the insiders believe that the cracks and cracks of plastering mortar and external putty are mainly caused by "internal" and "external" factors 1 In the aspect of "internal cause", the internal cause is mainly caused by the large drying shrinkage and fast drying shrinkage of some plastering mortar and putty products, resulting in the large internal stress damaging the mortar structure, and the crack is generally irregular crack, which is often called turtle crack Tortoise cracks are mainly caused by the fact that some manufacturers do not fully understand the properties, functions and technical principles of raw materials, the raw materials used do not meet the requirements, and the formula is not scientific, resulting in unstable product quality and poor crack resistance Soon after construction, large area cracks, hollowing and falling off appear The strength and anti crack effect of cement mortar are closely related to water The hydration and setting hardening of cement are a gradual and continuous process The results of hydration first, then setting, and setting hardening depend on the hydration conditions The more sufficient hydration, the better water curing, the longer curing time, the higher the strength, the smaller the shrinkage, and the better the anti crack effect The rate of hydration and setting and hardening of mud is obviously affected by the ambient temperature, that is, the rate of hydration and hardening is fast when the ambient temperature is high; the rate of hydration and setting and hardening of cement is slower when the ambient temperature is low Early dry, early hard and early strong cement mortar, due to poor water conservation and poor self-care ability, will produce too fast shrinkage, too strong shrinkage force, and easy to produce large area cracks In the research and practice, the late strength, stability and crack resistance of early dry, early hard and early strong cement mortar are worse than those of late dry, late hard and late strong cement mortar, which is also determined by the particularity of cement as inorganic hydraulic cementitious material The occurrence of turtle cracks is mainly related to cement No matter what type of cement, there is a problem of dry shrinkage From the test situation, the strength, stability and crack resistance of sulphoaluminate cement, white cement and other cement varieties in the later stage are not as good as ordinary portland cement The main reason is that these products have large shrinkage, fast dry shrinkage, strong shrinkage and easy to produce turtle cracks Ordinary portland cement is widely used in construction projects in our country It has a history of several decades, and its performance is very good As long as the hydration is sufficient and the water conservation conditions are good, its strength will be improved in a few years or even ten years At present, polymer mortar and cement putty are still mainly made of ordinary portland cement, and the models used are 32.5R or 42.5R The formula of polymer mortar and cement putty must be well controlled 2 In terms of "external cause", it is mainly caused by construction technology, foundation and natural environment Generally, unscientific and unreasonable architectural design and construction, foundation settlement and deviation, too thick one-time plastering during construction, obvious cracks in the basement before construction, stress caused by earthquake, large wind pressure, continuous high-temperature and dry weather after construction, etc will cause cracks Cracks and cracks are usually manifested in the form of transverse and vertical lines Or irregular There are different sizes of cracks Large cracks can be easily seen Small cracks may not be visible to the naked eye, but as long as water is poured on the dry wall, the micro cracks can be clearly seen There are basically no reliable materials and technical means to completely repair cracks and cracks, which will result in building decoration, decoration and waterproof The project and the future maintenance work cause great difficulties, because when the external wall cracks and cracks change with the external environmental conditions (foundation settlement, earthquake, etc.), temperature difference and dry humidity, the size and shape of the cracks will change constantly, that is, the size of the cracks will change at low temperature in winter and high temperature in summer, that is to say, the cracks will be large on rainy and sunny days in the same season Small can also change, which is also the most headache of cracks in roof, wall, underground waterproof engineering and maintenance practice Often after repair, within a year or even a few months, leakage begins again 3 Methods and technical measures to control and prevent cracks The above analysis shows that the generation of crack mainly comes from two aspects of "internal cause" and "external cause" The solutions of "internal cause" mainly focus on the production of products and the technical performance of raw materials, "external cause" is relatively complex, involving many aspects such as architectural structure design, construction technology and technical level, engineering quality supervision and management, natural environment condition, etc 。 1 For the crack resistance of polymer plastering mortar and cement putty, we should focus on the selection of raw materials, select high-quality raw materials, fully understand and understand the properties and mechanism of various raw and auxiliary materials, make scientific formula, and select high-quality products with strong functionality and stable and reliable performance, which can better prevent the occurrence of cracks 2 In architectural design, especially in the design of thermal insulation structure of external wall, the problems of foundation settlement, earthquake resistance, wind pressure resistance, stress release and environmental impact should be fully considered 3 In terms of construction technology, in order to avoid large dry shrinkage caused by plastering mortar and external wall putty, each plastering shall be thin and not thick Each plastering of plastering mortar shall not exceed 2.5mm layer thickness, and each plastering of external wall putty shall not exceed 1mm layer thickness 4 In dry mixed plastering mortar, external wall putty or common cement, adhesive with strong sealing property such as polyvinyl alcohol and latex should not be used excessively Such adhesive can quickly form film and seal cement micropores, and aggravate the dry shrinkage of cement, forming "hard shell" phenomenon, forming a large strength difference with the base course, that is, the strength of the surface course greatly exceeds the strength of the base course, which is easy to cause turtle Cracking, hollowing and falling off In addition, once the micropores of cement mortar are completely closed, it will not only affect the full hydration of cement, but also make the cement mortar lose the function of "free breathing" and self curing If the bad components in the wall can't come out with the water through the micropores, the service life of the wall will be poor 5 The design and construction of external wall insulation layer do not consider the release of internal stress in the insulation layer The whole wall is from the top to the bottom, dozens of floors high, without expansion joints Once there is a large stress, the whole insulation layer is plastering mortar, external wall putty, coating layer will inevitably produce cracks Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire 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