Exchange Platform □ Taiyuan City Construction Engineering Safety Supervision Station Huang Bin □ Beijing Zhenli High-tech Co., Ltd. Lin Yancheng Sun Guifang With the advancement of China’s energy conservation policies and standards, China’s building insulation technology has been widely developed, but due to various reasons, project quality problems Still emerging.
Whether it is the external wall interior insulation project, the sandwich core insulation project or the external wall exterior thermal insulation project with a relatively large amount of application, there are many quality problems in varying degrees. For example, lack of durability, cracks, moldy mildew, ups and downs, etc. Among them, the crack problem is the most prominent. In addition, due to the generally poor fire protection performance of our country's external wall insulation systems, the fire phenomena of external wall thermal insulation projects also occur from time to time. To control the quality of external wall thermal insulation projects, it is necessary not only to strengthen technical measures, but also to increase management efforts.
Technical measures As the thermal insulation system is composed of multiple layers of materials, the crack resistance performance should be considered in addition to the deformation capability of the materials of each layer, and the compatibility and matching of the materials should also be fully considered. The properties of crack-resistant protective layer materials in wall thermal insulation projects mainly involve the crack resistance of the screed mortar and the bond strength of the thermal insulation layer, the aging resistance, and the tensile strength, tensile elongation and alkali resistance of the reinforced mesh. And the deformability and compatibility of the finish layer (including the putty layer).
The wall thermal insulation project is a multi-layer organic composite, usually composed of an interface layer, thermal insulation layer, anti-crack protection layer, and a decorative layer, which are coordinated with each other to form an organic system. Practice has proved that the use of a single material does not guarantee the quality of the wall insulation project and must use multiple layers of composite materials at the same time. Therefore, ensuring the compatibility of materials of each structural layer is a necessary measure to control cracks.
The effective technical measure to overcome the cracks in the wall thermal insulation project is to adopt “releaseâ€
The constraining and anti-restraining capabilities of each adjacent layer of insulation material should be small enough, in which the elastic modulus and linear expansion coefficient of the material should be closely coordinated; second, the layers of the wall insulation engineering layer should have certain flexibility, ie, Certain deformation capacity, can effectively release stress under deformation conditions, and in the case of repeated deformation, will not produce fatigue damage; Third, if the adjacent layers have a large difference in deformability, flexible transition layer should be set, such as flexible Putty layer, sticky tile with flexible adhesive mortar, etc.; Fourth, rigid facing material should be provided with flexible separation joints, in the middle set with a certain deformation capacity of flexible plastic, such as flexible tile jointing glue, flexible block material joint glue; Fifth, when the area of ​​anti-crack protection layer is large and stress concentration is easily formed, stress relief joints should be provided.
Ribs (soft or hard reinforcements) to distribute stress, limit deformation, and prevent the occurrence of various stress concentrations. Reinforcement must consider its compatibility and durability. In the anti-cracking mortar, galvanized steel wire mesh can also be added. The anti-cracking mortar compounded by various fibers can also effectively absorb the expansion and contraction deformation caused by the influence of external natural conditions, and evenly spread the deformation stress to the surrounding area. To prevent cracks from occurring. The quality, alkali-resistance and retention of glass fiber mesh cloth and the location of the patch are also crucial to the system's crack resistance. The correct method is to use alkali-glass fiber-coated mesh cloth woven with alkali-resistant glass fiber to put it in a good-quality screed.
External thermal insulation works will be subject to greater thermal stress during actual use, mainly on the protective layer. Due to the better thermal insulation properties of the insulation material, the temperature of the protection layer can reach as high as 80°C in summer. The sudden change of surface temperature caused by sudden rain falling in summer can reach 50°C. The high temperature in summer will accelerate the protection layer. Ageing. Some organic binders in the protective layer are damaged by the influence of ultraviolet radiation, oxygen in the air, and moisture.
The external thermal insulation project should remain intact for at least 25 years, which requires it to withstand the long-term effects of periodic hot-humid and hot-cold weather conditions. The weather resistance test simulates the repeated action of the sudden drop of heavy rain and the temperature of day and night in the winter after high temperature and sun exposure. It is an accelerating weathering test for large-scale external insulation wall and is the most important test and evaluation of the quality of the external insulation system. Pilot project. The weather resistance test has a strong correlation with the actual project and can well reflect the weather resistance of the actual external thermal insulation project. According to the French CSTB test, from the comparison of the actual performance change of the external insulation system that has undergone several years of tests under severe climatic conditions with the laboratory weatherability test, in order to ensure the reliability of the external insulation system within the specified service life, It is very necessary to carry out the weather resistance test. Through this test, not only the long-term weatherability of the external insulation system can be inspected, but also the design, construction and material properties can be comprehensively inspected.
The following key technical factors need to be taken into account when sticking tiles on the external wall of an external wall: on the premise of protecting the insulation layer, the external insulation system shall be formed as a whole, and the load-bearing body of the facing layer of the tile shall be transferred to improve the strength of the surface layer bonded to the tile. To meet the requirements of the standard specification, prohibiting the paste of tiles in the absence of standard specifications.
It is necessary to consider the index of the external insulation material and its supporting materials, such as the ratio of crimping, bonding strength, alternating flatness, weathering stability, and the deformation of the entire external insulation system, in order to release and absorb thermal stress or other stress.
It is necessary to consider the impermeability of the external insulation material and the respiration and vapor permeability of the insulation system to prevent freezing bricks from falling due to freeze-thaw damage.
Improve the fire protection rating of the external thermal insulation system to avoid the occurrence of cavities after accidents such as fire. The loss of integrity of the external thermal insulation system is caused by large-area collapse under the influence of self-gravity gravity of the tile facing.
It is necessary to improve the seismic and wind pressure resistance of the external thermal insulation system in order to avoid the great damage to the external thermal insulation system in the horizontal direction after the occurrence of an accidental accident.
In certain developed countries in foreign countries, fire protection requirements for buildings over 18-20m in height prohibit the use of polystyrene boards as insulation materials. At present, under the condition that there are no perfect control standards in China, many high-rise buildings still use a single polystyrene board as the external insulation material, which brings about a certain degree of fire safety hazards to the buildings.
In order to make up for the poor fire resistance of domestic polyphenylene board and other organic insulation material external insulation systems and the potential for easy digestion under high temperature environment, organic insulation materials should be avoided in high-rise buildings. The best way is to use inorganic insulation material system. Such as rock wool board insulation system, or the use of high fire safety grade polystyrene powder particle insulation system. When non-organic insulation material systems are used, at least 10mm thick polystyrene powder particles should be applied to the surface of the organic insulation material to increase the fire protection rating of the entire insulation system. Large-scale fire simulation tests have confirmed that this practice is very reliable and can effectively delay the destruction of organic insulation materials caused by large fires. Generally, it can be delayed for about 50 minutes. This provides sufficient time for escape and rescue during fires.
Management measures 1. Strengthen external wall insulation construction technology training Currently, more and more categories of external wall thermal insulation materials, no matter which kind of thermal insulation materials, in order to achieve the desired energy-saving effect, and in line with national energy conservation standards and requirements, must strengthen the construction Special training for construction workers' insulation construction. Because the exterior wall insulation construction is different from the ordinary concrete mortar construction in addition to the material itself, there are many construction procedures, materials (products), the preparation of complex and high construction process requirements. If not according to the material's performance, characteristics and technological process to the construction, there will be many quality problems, which not only affect the quality of insulation, but also delay the construction period, resulting in economic waste. Therefore, strengthening the special training for external wall insulation construction personnel is the key to ensuring the quality of external wall insulation projects.
The external wall insulation construction technology is a systematic project, and technical training should be provided from the aspects of structural design, system and material properties, construction technology, site management, and quality supervision and management.
2. Formulation and Improvement of Related Laws, Regulations, and Technical Standards China's "Energy Conservation Law of the People's Republic of China" has issued a comparative principle of regulations for building energy conservation, with poor operability, and there is no specific law for the energy saving of civil buildings. Therefore, it is virtually impossible to promote energy efficiency in buildings.
The external wall insulation industry urgently needs to quickly establish a set of product standards, construction technical regulations and acceptance specifications. At present, the product standards of the external wall insulation system are only “Expanded polystyrene board thin plaster external wall insulation system†(JG149-2003), “Technical Specification for External Wall External Thermal Insulation Engineering†(JGJ 144-2004), and “Polystyrene Polystyrene Particlesâ€. External wall insulation system (JG158-2004), external insulation construction technical regulations are only part of the local standards, and construction acceptance standards and building energy conservation inspection standards are in the process of preparation. In short, the external insulation industry is still an emerging industry in China, and all kinds of standards are not complete enough. Some external wall insulation systems do not have any technical standards, and the market is still not standardized. Therefore, for relatively mature products, technical standards should be formulated in a timely manner and advanced patented technologies should be included in the technical standards so as to rapidly improve the overall technical level of the industry.
3. Standardize exterior wall thermal insulation market and implement external insulation system certification access system With the increasing demand for exterior wall thermal insulation products in the construction market, some foreign external wall thermal insulation products have also entered the domestic market one after another. As a result, some companies only aim for profit. They do not consider how to improve product quality and performance in their operations. They do not consider how to improve their own service systems and apply unqualified external wall insulation products to the project. This has led to a lot of project quality problems. The emergence of. The emergence of these problems has brought a great negative impact on the development of building energy conservation.
Therefore, in order to improve the quality of external wall thermal insulation projects, we must standardize the external wall thermal insulation market, mobilize the strength of all sectors of society, all departments and enterprises to form a joint force, strengthen the supervision and management of the administration and technology, standardize the operation of the market, crack down on counterfeit and shoddy products, adhere to the The wall insulation system supplier shall implement the principle of complete supply of system materials and implement the certification system of the external insulation system. It is required to provide perfect production technology, perfect quality standards and reliable quality management system for exterior wall insulation technology and materials. The engineering supervision unit shall supervise the materials and technical quality of the regulations and the quality of the construction units' work procedures as required. The external wall insulation project has not been signed by the supervision engineer and shall not be accepted. Effectively strengthen the protection of intellectual property rights, increase investment in research and development of advanced products, processes, and applied technologies, encourage and support technological innovation, and increase the promotion of high-quality products and technologies and take effective measures based on the current status of market economy. Protection and incentives.
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