In recent years, glass curtain wall construction has risen rapidly in China, the glass curtain wall has the advantages of strong integrity, light structure, good elastic connection, good seismic performance, easy to construct and easy maintenance. At present, China's glass curtain wall is mainly open frame, semi-hidden frame, hidden frame and all-glass curtain wall, etc. The materials used in the glass curtain wall are mainly aluminum alloy profiles and sealant two parts. Selection of materials according to the local climate, taking into account the beauty, practicality, durability and other factors, are described as follows:
2 glass curtain wall with aluminum alloy profile quality requirements
Aluminum alloy profiles have ordinary grade, high precision grade and ultra-high precision grade points, curtain wall with aluminum alloy profiles should be used in the high-precision grade should be the quality of the surface, wall thickness, thickness, hardness and other inspections.
2.1 Surface quality inspection of aluminum alloy profile surface quality inspection, should be in the natural scattered light conditions, observation and inspection, should not use magnifying glass, the surface quality should be in accordance with the following provisions.
2.1.1 The surface of the profile should be clean and the color should be uniform.
2.1.2 The surface of the profile should not have wrinkles, cracks, skinning, corrosion spots, bubbles, electric burns, flow marks, sticky and film (coating) layer shedding and other defects.
2.1.3 According to the provisions of the national standard "aluminum alloy building profiles" (GB5237-2004), the surface quality of aluminum alloy profiles, allowing the depth of longitudinal extrusion marks due to molds and the presence of minor craters, bruises, abrasions and scratches, etc., which in the decorative surface should be no greater than 0.06mm, in the non-decorative surface should be no greater than 0.10mm.
2.2 Wall thickness of the test glass curtain wall force rod using aluminum alloy profiles wall thickness should be in accordance with national standards "aluminum alloy building profiles" (GB5237-2004) and "Technical Specification for Glass Curtain Wall Engineering" (JGJ102-96) of the relevant provisions of the implementation. Inspection, not installed on the wall of the aluminum profiles available vernier ruler to select different parts of the measurement, has been installed on the wall of the aluminum profiles available metal thickness gauge for measurement.
2.2.1 For beams, columns and other major stress bars of the cross-section stress parts of the aluminum alloy profile wall thickness measured value shall not be less than 3 mm.
2.2.2 wall thickness inspection, should be used with a resolution of 0.05 mm of the vernier calipers or a resolution of 0.1 mm of the metal thickness gauge in the bars of the same cross-section of different parts of the measurement, measurement points should not be less than 5, and take the Minimum value.
2.3 film thickness test aluminum alloy profiles of various film not only decorative, but more importantly, to prevent the corrosive effect of harmful factors in nature on the aluminum alloy, therefore, the film thickness should not be too thin, but not too thick, on the one hand, to increase the cost of aluminum alloy, on the other hand, the film is too thick there is a possibility that the film and the aluminum alloy adhesion is reduced to make the film occurring bulging, cracking or even fall off phenomena, aluminum alloy profiles, film thickness test should comply with the following provisions Aluminum alloy profiles, the inspection of the film thickness should be in accordance with the following provisions.
2.3.1 According to the provisions of "aluminum alloy building profiles" (GB5237-2004), the minimum average thickness of anodic oxidation film should not be less than 15 μm, and the minimum partial thickness should not be less than 12 μm.
2.3.2 According to the provisions of "powder electrostatic spraying aluminum alloy building profiles" (YS/T407-1997), the average value of the thickness of powder electrostatic spraying coating should not be less than 60 μm. The average value of the thickness of the powder electrostatic spraying coating shall not be less than 60μm, and its local thickness shall not be greater than 120μm and shall not be less than 40μm.
2.3.3 According to the provisions of "Electrophoretic Coating of Aluminum Alloy Architectural Sections" (YS/T100-1997), the local thickness of electrophoretic coating composite film shall not be less than 21μm.
2.3.4 According to the provisions of "Fluorocarbon Paint Coating of Aluminum Alloy Architectural Profiles" (GB5237-2004), the local thickness of electrophoretic coating composite film shall not be less than 21μm. GB5237-2004), the average thickness of fluorocarbon spray coating shall not be less than 30μm, and the minimum local thickness shall not be less than 25μm.
2.3.5 Inspection of the film thickness shall be carried out by a film thickness detector with a resolution of 0.5μm. Each rod in different parts of the decorative surface of the measurement point should not be less than 5, the same measurement point should be measured 5 times, take the average, trimmed to the nearest whole number.
2.4 Hardness test according to "aluminum alloy building profiles" (GB5237-2004), aluminum profile mechanical properties can be done in the hardness test and tensile test only one (arbitration test for tensile test), aluminum profile hardness test is generally carried out with the Vickers hardness tester, because it is not easy to test on-site, so it is mainly used at present, the "Aluminum alloy Wechsler hardness test method" ( YS/T420-2000) clamp hardness tester for on-site testing.
2.4.1 Glass curtain wall project using 6063TS profile Wechsler hardness value, shall not be less than 8; 6063AT5 profile Wechsler hardness value shall not be less than 10.
2.4.2 When using Wechsler hardness to measure the surface hardness of profiles, the coating on the surface of the profile should be cleared cleanly, the measurement point should not be less than 3, and should be at least 3 points of the measured value, take the average value.
3 Quality requirements for sealants for glass curtain walls
Sealants mainly include architectural sealants (weathering adhesive) and structural sealants (structural adhesive) two categories. They have many performance requirements are similar, but the building sealant (weathering adhesive) more emphasis on resistance to atmospheric changes, ultraviolet resistance, aging resistance, etc.; and structural sealant (structural adhesive) is more important is the strength, extensibility, adhesive properties, such as mechanical performance requirements. Both should be selected according to the purpose of use.
3.1 The main performance of the building sealant (weathering adhesive) aluminum alloy glass curtain wall with building sealant (weathering adhesive) is mainly silicone sealant. Weather-resistant silicone sealant must be a one-component neutral adhesive, acidic and alkaline adhesive can not be used, otherwise it will give the aluminum alloy and the structure of the silicone sealant to bring adverse effects. The adhesive can react with water vapor in the air and harden gradually, therefore, contact with water should be avoided during storage to avoid deterioration, but the adhesive can be adapted to sunlight, rain, snow, ice, ozone and high and low temperatures after curing. Silicone sealant has a variety of colors, light-colored sealant UV resistance is weak, only for indoor projects, aluminum alloy glass curtain wall embedded joints should be dark. According to the "Technical Specification for Glass Curtain Wall Engineering" (JGJ102-96), the performance of weatherproof silicone sealant should meet the provisions of Table 1.
3.2 The main performance of the structural sealant (structural adhesive) aluminum alloy glass curtain wall with structural sealant (structural adhesive) is mainly silicone sealant. Because it connects glass and glass, glass and aluminum, bear wind, seismic action, self-weight and temperature changes, etc., in the curtain wall plays an important structural role, so its mechanical properties have high requirements. As a structural sealant should have two functions: (1) excellent sealing performance; (2) and the bonded material has good tensile bonding properties.
The tensile strength of dumbbell type can only reflect the function (1); tensile strength of H-type, function (1), (2) can be reflected, so only H-type bonding tensile strength to meet the actual needs of structural silicone sealant. Structural silicone sealant is divided into two kinds of single-component and two-component, according to the "Technical Specification for Glass Curtain Wall Engineering" (JG102-96), the performance of structural silicone sealant should meet the provisions of Table 2.
3.3 Select the use of construction sealant (weathering adhesive) and structural sealant (structural adhesive) should pay attention to several issues.
3.3.1 The two shall not be used in place of each other. In particular, the structural adhesive shall not be used as a weathering adhesive. Although the price of structural adhesive is expensive, more advanced, down to the weathering adhesive is a big instead of a small, but the weathering adhesive is mainly used for external building sealing, weathering has higher requirements, which is difficult to structural adhesive is competent.
3.3.2 Both must use neutral adhesive, should be used within the validity period, expired weathering adhesive and structural adhesive shall not be used.
3.3.3 Most of the weathering adhesive and structural adhesive currently used is imported, there are a small number of domestic, either imported or domestic, must hold the national certificate of conformity and a variety of performance test reports, when used in curtain wall projects, should also be in accordance with the provisions of Table 1 and Table 2, the two kinds of adhesive for the second performance test.
3.3.4 For the structural adhesive, in addition to various performance tests, should also be done with the compatibility of the contact material test, the so-called compatibility refers to the structural adhesive and these materials in contact, only play a bonding role, does not affect the bonding performance of any chemical changes.
3.3.5 In the construction of what kind of adhesive, according to the use of purpose and parts, construction conditions, batch size and other factors to determine the comprehensive economic and technical comparison.
4 Conclusion
The material is to ensure the quality and safety of the material basis of the curtain wall. The main materials in the curtain wall --- aluminum alloy profiles and sealants, etc. are not working alone, but are often interlinked, mutual constraints, mutual security. Most of these materials can be produced domestically, but due to the difference in production technology and management level, different manufacturers, the quality difference is still large. But as a curtain wall materials used should be in line with national or industry standards for quality indicators, unqualified materials are strictly prohibited. Because the curtain wall is on the outside surface of the building, the material will directly affect the durability and safety of the curtain wall.