MATERIALS INNOVATION & ENERGY SAVING IN BUILDINGS. Brief Discussion on Paste Construction of External Wall Insulation CHEN Meng-qun1, WANG Yan2 (1. Cixi City Construction and Installation Engineering Quality Supervision Station; 2. Cixi City Water Supply Company plays an important role.
China Classification No.: TU74: A Article ID: 1672-3791 With the continuous and rapid development of China's economy, improving energy efficiency, improving the indoor thermal environment, and saving energy and reducing consumption have become common goals. In the modern building, especially the high-rise building insulation system, the external wall insulation system plays a very important role.
According to the requirements of the No. 309 document issued by the Ministry of Construction, the Ministry of Construction Science and Technology Development Promotion Center has undergone extensive investigations and researches over the past four years, earnestly summarizing practical experience, relevant international standards and foreign advanced standards, and has widely solicited opinions and revised technical system programs to supplement earthquake resistance. On the basis of weathering tests, the “Technical Regulations for External Wall Thermal Insulation Engineering†was formulated.
In conjunction with the external wall insulation project actually constructed by the author in recent years, we should pay attention to understanding the issues related to the paste method in particular when using the protocol.
1 Several Problems to Be Paid Attention to when Using the Regulations 1.1 Contents of the Basic Rules Contents External thermal insulation works should not fall off from the grass-roots level when a rare earthquake occurs. This requirement is higher than the original "fortification earthquake."
The external thermal insulation project components should have physical and chemical stability. All constituent materials should be compatible with each other and should be preserved. In the event of possible biological infestation, the external thermal insulation project should also have anti-biological properties. In China, there have been reports of ants, mice destroying polyphenyl plates, and solvent-based paints destroying polyphenyl plates.
Under the conditions of proper use and normal maintenance, the service life of the external thermal insulation project shall be not less than 25 years. The external wall thermal insulation project built under the same standard technical conditions has a history of 40 years in Europe and its performance is still intact. 1.2 Performance requirements Content points The external wall insulation system should be tested for weather resistance according to the regulations.
After the weathering test of the external insulation system of the external wall, no blistering or peeling of the decorative layer, emptying or detachment of the protective layer, etc. shall occur, and no water seepage cracks shall occur. External insulation system with a thin smear layer, the tensile bond strength between the smear layer and the insulation layer shall not be less than 0.1 MPa, and the damage site shall be within the seat insulation layer. Several years and hundreds of engineering and product tests have proved that the large-scale weatherability test has a strong correlation with the overall performance of the system.
Polystyrene cast-in-place concrete external wall insulation system on-site bond strength shall not be less than 0.1MPa, and the damage site shall be located within the polystyrene board. If the damage site is located outside the polystyrene board, it proves that the system design has a weaker structural layer than the polystyrene board, and the overall structure of the system is unreasonable.
The adhesive strength of cement and cement mortar shall not be less than 0.60 MPa in dry condition, and shall not be less than 0.40 MPa after immersed in water for 48 hours; the tensile bond strength of polystyrene board shall not be less than 0.10 MPa in dry condition and 48 hours after soaking in water. And the damage site should be inside the EPS board.
The tensile strength of alkali resistance in the warp and weft directions of the glass fiber web must not be less than 750N/50mm, and the retention rate of the alkali-resistant tensile fracture strength shall not be less than 50%. 1.3 Design and construction points When designing the external insulation system, the system shall not be altered. Structures and constituent materials. It is necessary to ensure the complete supply of the system so as to ensure the performance of the system.
The external thermal insulation system shall cover the thermal bridge parts such as the outside openings of the door and window frames, the parapet walls, and the enclosed balconies; the thermal bridge shall be blocked.
For the external insulation system of mechanically-fixed polyphenylene steel wire mesh panels, the influence of thermal bridges of the fixtures and the supporting members should be taken into consideration.
During the construction period of the external thermal insulation project and within 24 hours after the completion of the construction, the base layer and the ambient air temperature shall not be lower than 5*C. In summer, the sun should be avoided. It is forbidden to work on windy weather and rainy days above Grade 5.
2 Forms of External Wall External Insulation Forms of external insulation are various and widely divided into spray method, pouring method, paste method, and dry hanging method.
The application scope of exterior insulation is relatively extensive, especially suitable for exterior wall insulation of high-rise and super high-rise buildings.
The advantage is that the generation of cold (hot) bridges can be avoided, the thermal insulation effect of the external wall is improved, and the comfort of the house is improved; the comprehensive efficiency is good, the indoor use area of ​​the house is increased, the investment return rate is increased, and the insulation is reduced Material thickness and consumption. With the same insulation effect, 40-50% of the insulation material is saved compared to the internal insulation and the sandwich insulation; the service life is long, and the maintenance cost of the building is low; the difficult problem of the interior insulation wall surface being difficult to be renovated is solved; it is applicable to newly-built energy-saving buildings. It also applies to energy-saving renovation of existing buildings.
The disadvantage is that the construction process is complicated, which increases the manual and mechanical consumption of the project construction; the application time is short, the practice is not uniform, and some common defects such as surface cracking and shedding often occur; the one-time investment is large, and the grid cloth is increased. , wire mesh and other expenses investment.
At present, the more common practices are polystyrene powder pellet insulation forms, paste-type EPS panels (polystyrene sheets), external wire mesh EPS board insulation forms, and paste-type extruded board insulation forms.
Since the external thermal insulation system is placed on the outside of the wall and covers the entire external wall surface, it can effectively reduce the influence of the cold (thermal) bridge and avoid the direct contact of the wall with the outdoor atmosphere. Therefore, the energy-saving effect is good; at the same time, it can be avoided. Or reduce wall cracks caused by excessive changes in temperature and humidity; due to the waterproof effect of the insulation system, it will help improve the waterproof and impermeability of the wall; does not occupy indoor space; applies to both new construction and both There are energy-saving reconstructions of buildings, and therefore the external walls of energy-saving buildings should use exterior insulation systems as much as possible. In a variety of exterior insulation systems, the thermal insulation system of pasted polystyrene board and paste extruded board is an ideal form of insulation and energy saving. It should be actively promoted and applied.
3 Paste method design, construction of technical points Paste method of construction Exterior wall insulation system is mainly composed of insulation board, wiping surface layer, decorative layer, insulation board by adhesive (anchor bolt if necessary) fixed on the base wall.
For the convenience of construction workers, the length of the insulation board should not be greater than 1200mm, and the width should not be greater than 700mm. For safety reasons, when the insulation board is affixed to a building height of 30m or above, anchor bolts should be added on the basis of the adhesive to assist fixing.
Paste construction external wall insulation projects must pay attention to the design of sealing and waterproof structure, important parts must ensure that water does not penetrate into the insulation layer and the base layer.
The exterior wall external insulation system shall be well-prepared for the edge treatment of the external insulation system at the mouth and at the foot; the construction joints, the corners of doors and windows, and the yin and yang angles shall be well-prepared for the local reinforcement mesh; waterproof and heat-preservation structures shall be prepared at the deformation joints. deal with.
When the decorative layer of the insulation board is a facing brick, a galvanized steel wire mesh should be used instead of the alkali-resistant glass fiber mesh cloth, and the weight of the tile should be effectively transmitted to the main structure by calculating the number and distribution of the anchoring elements according to the load-bearing needs. To avoid the polyurethane rigid foam insulation layer to withstand the weight of the tile.
The base wall surface should be clean and free of oil, dirt, etc.
The main precautions when sticking insulation boards; paste the insulation board should adopt the dot frame method, that is, apply the appropriate width and thickness of adhesive on the entire back of the insulation board, and then evenly apply a certain amount, a certain thickness, and a diameter of about 10 in the middle part. 0mm round sticking point, the total paste area is not less than 40%; when the building height is 60m and above, the total paste area is not less than 60%. The paste of thermal insulation board should be carried out from the bottom up, the horizontal direction should be from the corner and doors and windows Paste to both sides; paste the insulation board should be gently and evenly squeezed, and tap the board surface, if necessary, should be used to help anchor fixed; row plate should be up and down the wrong seam, yin and yang angle should be erroneous lap.
When sticking the insulation board around the door and window openings, the whole insulation board should be applied. The joints of the insulation board must not be left at the corners of the door and window openings. The minimum size should be more than 200mm when laying the insulation board at the corner of the wall. When the mechanical anchor is used to assist the fixing of the insulation board according to the design requirements, it should be done after the adhesive is cured for 24 hours; the depth of the anchorage into the wall is not less than the design (or node diagram) ) Requirements, the number and type of anchors are determined according to design requirements.
When the insulation board is transported or installed on the wall, the operating site wind power should not be greater than 5 levels.
At present, according to the growing demand for external wall insulation systems, a series of procedures and guidelines will soon be promulgated. It is believed that through the joint efforts of a large number of scientific and technical personnel and construction units, external wall insulation will have a promising future in energy conservation and consumption reduction.
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