Basic knowledge of metal roof steel structure waterproofing
The development of waterproof materials can be various today. The flexible waterproof materials of metal roofing and steel structures are classified in the form of attaching to the waterproof base layer, and are roughly divided into two categories: coil waterproofing and coating waterproofing. However, when the waterproof material is converted into a waterproof layer, a key link in the middle is construction - that is, the secondary processing of the waterproof material.
What are the characteristics of coiled material waterproofing and coating waterproofing?
The traditional waterproof coiled material should be considered as paper based asphalt felt. When the asphalt felt is used as the waterproof layer, the construction asphalt must be used as the bond to pave the sand and gravel: the general practice is three asphalt two felt or four asphalt three felt. Due to the high labor intensity of the above method, it is difficult to support the construction technology. A large amount of waste gas generated during the preparation of asphalt seriously pollutes the environment. It is impossible to construct in places where fire cannot be used. Fire and accidents are easy to occur. The secondary maintenance of the steel structure roof is difficult. Because of the above reasons, the asphalt felt waterproof layer is basically eliminated.
The new generation of waterproof materials are developing in the direction of light weight, convenient construction, no pollution to the environment, durability and beautiful color. Therefore, waterproof coiled materials include paper based asphalt felt, rubber coiled materials, membrane modified asphalt coiled materials and various synthetic polymer waterproof coiled materials. The coating waterproof materials are developed from modified emulsified asphalt plastic ointment polyurethane waterproof coating to environment-friendly synthetic polymer color waterproof coating.
Up to now, waterproof materials can be developed in a wide range of varieties. In a word, the emergence and application of various waterproof materials have their own advantages, either easy to obtain materials, or low cost, or not cheap but durable, or different waterproof occasions with different uses. In addition to cost, climate, region, building function and environmental protection, the structure of buildings is an important factor in the selection of waterproof materials for metal roof steel structures. If it is suitable to use waterproof coiled materials, it is not suitable to use coating for waterproof, and it is not necessarily suitable to use coiled materials where it is suitable to use coating. For another example, it is not suitable to use coiled materials for waterproofing: wet base course, parts with poor drainage or perennial water accumulation, uneven base course, many protruding embedded parts base course, back surface waterproofing, water tank waterproofing, and areas with large and more typhoons all year round. For example, the base course is not suitable for coating waterproof: the bottom course of wooden slope tile house is waterproof.
The disadvantages of waterproof coiled materials are as follows: during waterproof construction, the waterproof coiled materials should be cut according to the shape of the waterproof base course. For the base course with complex shape, multiple pieces of waterproof coiled materials need to be spliced. It is difficult to bond the overlapping parts of waterproof coiled materials. Because multiple pieces of splicing affect the beauty of the waterproof layer. In addition, complete sealing will become the main problem, and the overlapping part of coiled materials is the one with more water hazards and opportunities. Moreover, the waterproof roll has decades of durability, but at present there are few adhesives matching it in China. Because of the environment and the bonding material itself and other factors, the bonding function is often lost in advance, and the resulting waterproof failure will be self-evident.
The protection and maintenance of waterproof coiled materials after construction are also difficult problems. The exposed waterproof layer is very important to prevent external mechanical damage. The bonding between the waterproof coiled material and the base course, whether full paving, spot paving, strip paving or empty paving, will be a water layer between the coiled material and the base course, regardless of any part λ The entire waterproof function of the layer connected with it will be completely lost due to the penetrating damage, degumming and gluing (even if there is only one place). If the damaged and defective parts cannot be found, the local repair is impossible, and the waterproof layer must be redone.
For those waterproof layers with concrete protective layer, although external mechanical puncture is no longer possible, it is not suitable to make protective layer along the trench. In addition, there is a high possibility of long-term ponding along the trench due to sewer blockage and other reasons, and the water tightness of the waterproof layer shall not have any defects. Therefore, there is less chance of successful waterproofing of coiled materials along the ditch. Due to the complex shape along the ditch, it is difficult to seal the overflow tunnel, water outlet and other parts, and the waterproof coiled material has also become the key technology. Moreover, due to the agglomeration of domestic and production wastewater along the ditch, harmful ingredients accelerate the decomposition, aging and even failure of coiled material bonding materials.
