PUF (polyurethane foam), EPS, XPS are all superior thermal insulation materials, and their insulation systems are superior and inferior. The author combines the practice of PUF insulation engineering for many years to make a comprehensive comparison of the three for the industry colleagues.
Polyurethane (PUF) insulation system; EPS insulation system; XPS insulation system; compared with foreign countries, polyurethane foam (PUF) is applied to building wall insulation, which can be traced back to several decades ago. And commercial building wall insulation and residential roof insulation renovation, and China is mainly used for refrigeration insulation and heating insulation. With the development of the petroleum industry, the cost of PUF raw materials has decreased relatively, PUF has been applied in building insulation, and the price gap between EPS (expanded polystyrene) and XPS (extruded polystyrene) has been narrowing, combined with other comprehensive Factors, in recent years, PUF has emerged in China's energy-saving building exterior wall insulation. The author combines the practice of PUF insulation engineering in the company in recent years, and comprehensively compares the three, and puts forward a hole, so please.
The basic physical properties of 1PUF, XPS and EPS materials are compared. The basic physical properties of the materials are shown in Table 1. Table 1. Comparison of basic physical properties of PUF, XPS and EPS materials. Thermal conductivity of the sprayed sheet. Compressive strength (kPa) Rate (%.) Flame retardant degree Self-extinguishing combustion stage dimensional stability From the comparison of basic physical properties of materials, PUF has advantages in thermal conductivity, compressive strength and temperature resistance. XPS has compressive strength and moisture resistance. Advantages, EPS has no advantage in all aspects.
2 actual engineering insulation system comprehensive comparison 21 overall insulation performance table 2PUF, XPS, EPS overall insulation performance comparison project remarks spray plate thermal conductivity gap correction coefficient material thickness ratio low layer no 7 layers below auxiliary nail heat loss multi-layer no small 7-layer high-rise There is no gap correction coefficient for convection heat transfer of more than 60m: because the actual engineering insulation layer has cavities (point sticking) and gaps (slab joints, especially winter shrinkage is more obvious), under positive and negative wind pressure and temperature difference There is a certain convective heat transfer, so according to the actual experience, a certain material thickness is added to make up for the heat loss, and the degree of the increase is expressed by the theoretical multiple of the material design thickness.
From the comparison of thermal insulation performance, PUF insulation system has obvious advantages, followed by XPS system and EPS system.
22 overall bond strength insulation system overall bond strength comparison see Table 3. Table 3 PUF, XPS, EPS overall bond strength comparison project remarks spray plate bond strength (MPa) (self-destruction) bond form full-stick point bond The initial strength of the area is excellent. The anchoring aid needs (more than one layer). The outer sheath is less stressed. From the perspective of bond strength, XPS is the best on the data, followed by PUF and EPS. However, the PUF spray insulation layer is full-adhesive, and the bonding area is 2 times larger than XPS, so its overall strength is still greater than XPS; plus the initial strength of PUF is good, no anchor fixing is needed, and PUF is still in the first place. . When the EPSXPS board is bonded, the initial strength is poor, and it is easily affected by wind, human collision, and self-gravity, and it is easy to cause bonding failure (virtual adhesion). 3Comprehensive comparison of construction comprehensive comparison See Table 4. Table 4 PUF, XPS, EPS construction comprehensive comparison project Remarks Spraying board sticking per shift construction amount (m1/d) 3 people/group operation input cost size Spraying machine technical level requirement is higher High comprehensive management level General environmental enclosure requirements High general operating temperature (C) Operating wind (level) Safety requirements Same scaffolding requirements Same to wall error requirements Not limited to special-shaped wall construction Easy to be difficult PUF sheet insulation system with EPS, XPS insulation The system process is the same, so the work efficiency is the same. However, the PUF spray insulation system is not the same. Under the same working conditions (3 people per shift), PUF can be sprayed with 200m2/d300m2/d per group. If the two sprayers work alternately, it can reach 500m2/d, which is EPS and XPS. The pasting method is several times more effective.
Based on the above comparison, PUF spraying construction has high investment, high efficiency and high output. The investment in equipment in the early stage is not a problem, and it can be solved both at present and in China. The key issue is the training of qualified sprayers. It is not necessary to add 10,000 square meters of work practice for half a year. Therefore, it is recommended that domestic specialized institutions should be established, from theory to practice, to train a large number of spray technicians to meet future development needs. At the same time, the EPS and XPS insulation systems have low initial investment and easy entry, resulting in fierce competition and uneven system quality, which is one of the causes of quality accidents in many projects.
4Comprehensive comparison of engineering costs with high-rise cast-in-situ concrete wall insulation in Shenyang area, 50% energy-saving standard, price level in the first half of 2006 as an example. The comprehensive comparison of engineering costs is shown in Table 5. From the perspective of overall construction cost, energy-saving 50% standard building The external wall spraying PUF has a higher price, which is 20% higher than XPS and 30% higher than EPS. If the PUF is painted on the exterior wall of the building according to the 65% energy saving standard, the cost is about 10% higher than the XPS. The EPS may not be selected due to the excessive thickness and other properties (at least the northern region, high-rise buildings, and parts of the coastal winds). ).
Table 5 PUF, XPS, EPS insulation system engineering cost comprehensive comparison (yuan / m2) project remarks spraying board adhesive base surface cleaning, line bonding adhesive insulation material fixed auxiliary nail grid cloth cracking mortar average thickness 4 surface labor cost management Fei Li tax total 5 other aspects 51 - times construction surface flatness PUF spray molding, the surface flatness is worse than the sheet bonding surface, need to manually smooth or use light aggregate insulation mortar leveling, increase working hours and costs. However, under normal circumstances, the surface error of newly built walls exceeds 20mm. Both XPS and EPS systems need to be leveled or cut with cement mortar, which also increases certain working hours and costs. Compared with the two, the economic difference is not big.
52 fire performance å© 1, at 8, ugly 8 are high-molecular organic materials, are all ugly combustible materials. Burning level PUF, EPS can achieve B1 level (oxygen index>32), XPS can only achieve B2 level (oxygen index>26).
When XPS and EPS encounter fire, the temperature begins to shrink and melt when the temperature is >80C. After combustion, a cavity is formed and there is a dripping phenomenon, which is likely to cause a large area to overfire and spread. PUF does not melt and shrink, and forms a carbon skeleton after combustion. The cavity is small and does not drip, which can hinder the spread of fireworks.
The concentration of smoke and the amount of heat released after burning are almost the same.
53 Overall Waterproof Performance One of the fatal problems of the XPS and EPS sheet bonding system is that once the surface layer is cracked (this is almost a common problem in China's buildings), the rainwater will penetrate into the insulation layer through the seams under wind pressure. If this phenomenon occurs during the spring, autumn and winter alternation in the northern region, there will be freezing and thawing alternation damage, and the consequences are unpredictable.
Spraying PUF insulation layer is generally applied in multiple passes, and each layer of PUF surface layer has a dense skin, which can play a waterproof (seepage) effect.
Even if the surface protective layer is cracked, it will not seep into the inside of the insulation layer, greatly reducing the damage caused by the freeze-thaw interaction. Therefore, the PUF can be directly sprayed on the top of the layer to form a heat-insulating and waterproof integrated surface layer, and only one protective layer can be used thereon. The process is simple, the construction is rapid, the performance is reliable, and the foreign country has been applied on a large scale. At present, the country has also formed a certain scale of application, and has relevant industry standards.
5.4 Diversion performance The vapor permeability of all foams is related to the closed cell ratio of the internal cells. The higher the closed cell ratio, the worse the vapor permeability. The closed cell ratio of PUF cells can be adjusted freely between 95% and 25%. The closed cell ratio is controlled at about 90%, which can meet the requirements of water vapor permeation of general walls, and the thermal conductivity and dimensional stability can be kept within the optimal range.
The XPS closed cell ratio is relatively high, almost 100%, and cannot be adjusted due to process limitations. Excellent water resistance, but extremely poor vapor permeability. The insulation system can only be immersed in water vapor by the seams or openings.
The EPS microbeads have a relatively high closed cell ratio (almost 100%) and cannot be adjusted due to process limitations. However, there is a certain small gap after the foaming between the beads is formed twice, and the water vapor is infiltrated by this small gap. The gap size is related to the EPS density and the secondary foam fusion degree, so the relative vapor permeability is good. In addition, the slats also bear a certain water vapor permeability.
The steam permeability can also be adjusted from the wall and insulation system structure. If the insulation material over-emphasizes this function, it will affect its main function insulation performance.
6 Preliminary conclusions EPS insulation system is suitable for low-rise building exterior insulation with low energy-saving standards, low wind resistance and simple shape. The system has low construction efficiency, low technical requirements for workers, simple tooling, and lowest engineering cost. New construction and reconstruction projects can be used.
The PUF system is suitable for multi-layer and high-rise buildings with high energy-saving standards (more than 50%) and complex exterior insulation. New construction and renovation projects are not limited. The comprehensive cost is high, the construction efficiency is high, the tooling investment is large, and the technical requirements for workers are relatively high.
Due to the new materials and new processes, the XPS system has only been used for 5 years in China, and the industry has been controversial. However, XPS has been approved by the industry for insulation with high humidity (such as underground parts) and rigid requirements (such as the ground and roofs). Other aspects (especially the exterior wall) still require actual large-scale engineering applications and years of inspection.
The development of PUF spray insulation system is inseparable from professional and socialized cooperation. It is necessary to form an industrial chain in the production of basic raw materials, special foaming materials, spray personnel training, foam machinery and parts supply, technical consultation and research and development. Improve efficiency, reduce costs, and promote its large-scale application.
Mechanization of construction insulation construction site is the future development direction. On-site construction is affected by human factors, and quality is difficult to control. The low input, low level and low starting point of the page are likely to cause a spurt of enthusiasm, resulting in continuous engineering quality accidents. On the contrary, the project has high investment and high starting point. As long as it is properly managed, the quality is guaranteed, and there will be high returns in the short term to achieve a win-win situation for enterprises, users and society. 23 Harbin introduces two new technologies for external thermal insulation. This newsletter, near Harbin Municipal Civil Engineering Society and Harbin Tianshuo Building Materials Industry Co., Ltd. jointly held a new technology exchange meeting for building insulation.
At the meeting, Kang Yufan, chairman of Harbin Tianshuo Building Materials Industry Co., Ltd. introduced two new thermal insulation technologies to the conference.
TS dry hanging insulation waterproof decorative integrated external insulation complete technology, using a variety of decorative materials and PU, EPS, XPS and other insulation materials combination, can be cast on-site polyurethane, can also produce composite panels in the factory, dry construction on site, The whole process of non-wet operation has realized the factory production and assembly construction of the external thermal insulation system. TS mold-cast polyurethane external thermal insulation complete technology, using anti-adhesive template casting rigid foam polyurethane, to solve the floating loss, pollution, surface unevenness, poor line angle accuracy, uneven thickness of the insulation layer, volume shrinkage, etc. problem. The technology can be applied to paint finishes, tile finishes, fourth-generation real stone paint finishes, etc. It can also be used in conjunction with glass curtain walls, molybdenum-plastic panel curtain walls, stone curtain walls, etc. It is widely used in new houses and public buildings in the north and south. Energy-saving standard exterior wall insulation project. The side pressure template strengthens the good bonding performance of the polyurethane, thereby forming a 100% cavityless bonding, so that the technology can be directly constructed in the existing building energy-saving renovation project such as tile facing.
The two technologies can not only meet the standard requirements of energy saving of 65%, but also meet the needs of various types of building exterior insulation in areas such as severe cold regions and coastal windy and rainy areas in construction technology, etc., which have been successively in Liaoning, Heilongjiang, Shandong, Inner Mongolia and Zhejiang. Shanghai, Shanghai and other places have become a number of external thermal insulation projects, which have been widely praised. Among them, on-site mold-casting polyurethane technology has been used as the basic technology, and it has been incorporated into the Polyurethane Energy-saving Technology Promotion Working Group of the Ministry of Construction.
1 Qi Xiaodong. The choice of external thermal insulation polystyrene board. New building materials, (2006.5)
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