Low temperature resistant exterior insulation system in severe cold area

Mianchun Mangchun 1 (1. Jilin Provincial Architectural Design Institute Co., Ltd., Changchun 130051, China; 2. Jilin Kelong Decoration Engineering Co., Ltd., Changchun 130022, China) The low temperature resistance, low temperature resistant materials and low temperature construction technology of plaster exterior insulation system, aiming at the climate characteristics of severe cold regions, put forward a set of low temperature construction technology and supporting materials to solve the low temperature construction of thin plaster exterior wall insulation in severe cold regions. The problem is to ensure the quality of low temperature construction.

External thermal insulation system; low temperature resistance; low temperature construction; polymer modified mortar in the north of the three regions (cold and cold regions), the winter temperature can be as low as -30C40C, the freezing period is as long as 4 to 7 months, and the construction period is very short ( 5 4 months). Therefore, in the severe cold area, the design and construction of the thin plastering exterior insulation system has its particularity.

1 Characteristics of chilling area 126-2000 exterior wall facing brick construction and acceptance procedures Appendix A Building climate zoning indicators: l, VI, VI area average temperature S5C for more than 90d. Among them, Area I is located in the northeast of Heilongjiang Province and Jilin Province, most of Liaoning Province, Inner Mongolia Middle and North, Shaanxi, Shanxi, Hebei, and northern Beijing. The average temperature of S5C is over 145d, and the annual rainfall is 200mm "800mm. It is a low-temperature general wet area; the VI area covers the whole territory of Qinghai Province, most of the northwest, southwestern Sichuan, southern Gansu, southern Xinjiang, and the average temperature of S5C is 90d~285d, which is a low-temperature dry area; Most of them, northern Gansu and western Inner Mongolia, the average temperature of S5C is 110d480d and above, which is a long-term low-temperature dry area. These three areas cover most of the northern and western China, and are cold regions in northern China with long heating period. It is the main winter heating area and a key area for building energy conservation.

The cold regions in the north are cold in winter, most of them are relatively dry, and some areas have certain rainfall. In addition to the requirement that the external thermal insulation system has low temperature resistance (such as -30C~40C), the system also requires low temperature construction performance, which can be low. Construction under 5C temperature conditions will extend the construction period and meet the engineering needs. To this end, Jilin Kelong Decoration Engineering Co., Ltd. carried out a large number of experimental research. After engineering tests, it summed up a complete set of supporting technologies for low temperature resistant external insulation systems.

2 In the cold area, the external wall insulation system requires materials for the external wall insulation system: base treatment materials (base layer reinforcement and repair mortar), adhesive (adhesive polystyrene board), polystyrene (EPS) board, plastering Pulp, alkali-resistant glass fiber coated mesh cloth and various decorative materials.

21 base treatment materials and adhesive (adhesive benzene board glue) base treatment materials and adhesives (adhesive polystyrene board glue) are inside the external insulation system, even in the coldest winter, such as -40C, the treated base The temperature is also higher than 5C. Therefore, the base treatment materials and adhesives (adhesive polystyrene board) used in the exterior and exterior insulation systems in severe cold and cold areas are the same as those in other areas. However, the construction period in the cold regions of the north is short, and many projects require completion in the same year. Therefore, it is required that the materials must be strong and not return to alkali, and can adapt to construction below 5C.

EPS parts can be used for a long time under very low temperature conditions. Even under -180C ultra-low temperature conditions, the EPS material itself will not undergo structural changes, but it should be considered for dimensional changes. The EPS plate has a thermal expansion coefficient of 0.05 mm/cm, and the EPS plate size changes by about 0.1% (1 mm/m). If the temperature is as low as -40C, the inside of the external thermal insulation system is 5C, the temperature difference is 45 °C, and the theoretical difference between the outer and inner dimensions of the EPS plate is 4, and stress is generated on both sides of the EPS plate. In addition, insufficient storage time of the EPS board (less than 42d) will also increase the shrinkage deformation of the EPS board. Therefore, the outer wall thermal insulation project in the northern cold area requires the storage period of the EPS board to be >42d, otherwise it will shrink by 0.3%~0.5% due to insufficient storage period, which is equivalent to the inner and outer dimensions of the EPS board under the thermal expansion and contraction of 45mm/m. It is easy to cause cracking.

In addition, the point-viscosity-cavity structure should be used to disperse the stress, and 500mm500mm EPS board should be selected to reduce the effect of thermal expansion and contraction, reduce thermal stress, reduce shrinkage deformation and prevent cracking.

The 8th phase of building energy-saving 2.3 reinforced glass fiber mesh cloth commonly used reinforced glass fiber mesh cloth has two types of medium-alkali glass fiber coated mesh cloth, alkali-resistant glass fiber coated mesh cloth. The function is to enhance the crack resistance of the polymer mortar surface layer, and to resist the calcium strontium oxide (alkaline) produced by the cement dissolution. The alkali resistance determines the service life of the outer wall outer insulation surface layer, which is very important.

The medium-alkali glass fiber coated mesh cloth is woven into a mesh cloth with medium alkali glass fiber, and the surface is coated with various alkali-resistant organic polymer materials (such as furan resin, epoxy resin-silicone, polyphenyloxane, Phenolphthalein resin, polyvinyl acetate-zinc salt, vinylidene chloride-zinc salt and other materials, under normal conditions, have good alkali resistance. However, due to the thin organic polymer coating on the surface of the mesh cloth, the coating becomes brittle under the action of low temperature. Under the action of the thermal expansion and contraction stress of the EPS board-coating layer, the coating layer will produce cracks and the surface layer. The alkaline calcium sulphate produced by the dissolution of cement can penetrate from the cracks, corrode the glass fiber, and the glass fiber will quickly fail, causing the surface layer to crack. Therefore, the outer wall insulation system in the cold regions of the north cannot use medium-alkali glass fiber coated mesh cloth.

The alkali-resistant glass fiber coated mesh cloth is obtained by drawing a glass containing zirconia having an alkali resistance content of 14.5% or more and titanium oxide of 6% or more. The material itself has excellent alkali resistance and has been recognized by domestic and foreign experts. The surface is also coated with a flexible organic polymer coating, which has excellent low temperature resistance and alkali resistance. Even if the surface coating is damaged, the fiber itself has strong alkali resistance. Alkali-resistant fiberglass mesh fabrics must be used for exterior insulation systems in severe cold and cold areas. In the region, when the ambient temperature is about 30C in summer, the temperature of the direct sunlight is about 50C, and the inside of the external thermal insulation system is about 24C. The temperature difference is only about 25C, and the stress caused by thermal expansion and contraction is small. The summer temperature is high, and the alkali-resistant glass fiber coated mesh cloth is flexible and can improve its anti-expansion force without causing cracking and breaking.

In addition, considering the low temperature resistance of the external thermal insulation system of the northern cold region, the standard mesh should use an alkali-resistant glass fiber coated mesh cloth with a base fabric weight of 160g/m2 or more, and the tensile strength is greater than 1250N/50mmX200mm to increase the wipe. The crack resistance of the surface layer.

The outermost 3mm 5mm thick surface coating layer of 24 plastering exterior wall insulation system is a polymer modified GRC protective layer composed of polymer mortar-alkali-resistant glass fiber coated mesh cloth made of plaster and cement. The inner side is affixed with the EPS board, and the surface coating material is the key material that determines the life and performance of the exterior insulation system. The layer material should have flexibility, gas permeability, water resistance, impact resistance, durability, low temperature freeze-thaw resistance and adhesion (for EPS board, alkali-resistant glass fiber coated mesh cloth and facing materials), The base surface of the facing material must also have strength.

The polymer modified GRC protective layer is located at the outermost side of the external thermal insulation system, and the surface is a very thin veneer layer, that is, it is almost directly in contact with the atmosphere, and is in a low temperature environment during the severe winter season, requiring the protective layer to have better resistance. Low temperature, the protective layer should have certain flexibility under low temperature (such as -30C40C), with low temperature crack resistance, impact resistance and low temperature freeze-thaw resistance. This is proposed for the external thermal insulation system in the cold regions of the north. Special requirements are very important. Since the temperature in the cold regions of the north reaches -40C when it is coldest, we have improved the freeze-thaw test requirements for the surface layer. The test temperature is adjusted from the standard -20C0C to -40cc, and the number of freeze-thaw cycles is from the original. 10 times to 100 times, after 100 freeze-thaw cycles, the test piece did not change. The summer temperature difference is small, but the temperature is high, and the protective layer (the surface layer polymer mortar-glass fiber mesh) has good flexibility, so there is no cracking problem.

At the same time, the low-temperature construction performance of this kind of product is excellent, mainly reflected in two aspects. One is the material aspect. The common material requires the construction temperature to be above 5C to be constructed, and the product we developed uses a special film-forming auxiliary. And special admixtures can shorten the construction period; second, the construction process, after special construction process to ensure the completion and quality of the project on time, such as the Changchun Jilin Institute of Architecture and Engineering, the family building, Changchun Wuhuan Golf Home, Changchun Regal Garden, etc. In the project, the outdoor temperature during construction has been lower than -5C, and the above method has been used for construction. So far, there have been no problems in the past seven or eight years.

In addition, the protective layer must be strong and alkalinized, which is the basis for ensuring a high quality finish.

25 matching facing materials The finishing layer on the base surface of the protective layer of the outer wall thermal insulation system in the northern cold region, in addition to the performance, decorative and service life of the facing materials, special emphasis on low temperature construction performance and resistance Low temperature. Generally, materials with better flexibility should be selected. The multi-layer elastic decorative layer can meet the needs of the base decoration of the protective layer of the external thermal insulation system in the cold and cold regions. The multi-layer elastic decorative layer refers to a thick coating, a embossed coating, a large floating point real stone paint, an elastic paint, a sealed alkali elastic large sand + paint, and the like.

In addition, there is also a low-temperature coating for the facing materials for external thermal insulation. It is a provincial-level scientific research project undertaken by Kelon. The film is resistant to -40C freeze-thaw 30 cycles and other performances have reached national standards. Has passed the provincial results appraisal. The product was tested by Heilongjiang Provincial Engineering Quality Supervision and Inspection Center. The coating passed the -40C low temperature freeze-thaw cycle 30 times, and the -40C~+50C coating was resistant to temperature change 10 times. The product performance reached the domestic leading level and won the Ministry of Construction Huaxia Technology. The third prize of the results.


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