In 2009, the CCTV new site fire, the Shanghai Jiaozhou Road apartment fire in 2010, and the Shenyang Imperial Wanxin Hotel fire in 2011, the fire caused by the building exterior insulation materials pushed the doubts about the fire insulation performance of the building exterior to the cusp.
Whether the external wall insulation material has fireproof function, whether we are to put the building in the fire hazard in order to achieve the building insulation and energy saving goal, what kind of external wall insulation system can be used to achieve both energy conservation and fire prevention. What materials are selected to meet the dual functional requirements of the building for insulation and fire resistance have become a problem for many construction, design and construction units. The inorganic thermal insulation mortar with Class A combustion performance provides a practical solution for the thermal insulation and fire resistance of the building exterior wall insulation system with its excellent flame retardancy and excellent heat preservation.
This paper takes a residential community in East China as an example to introduce and explain the three main aspects of the material properties, construction technology and quality common disease prevention and control of the exterior wall inorganic thermal insulation mortar insulation system with the facing brick as the facing layer, for the majority of construction technicians. And use.
A residential area in East China has a construction area of ​​140,000 hours. It consists of 19 12-storey buildings and 2 18-storey high-rise buildings. The height of the 12-storey building is 42m, and the height of the 18-storey building is 51.5m. The outer insulation is made of vitrified beads. Inorganic thermal insulation mortar system, the outer facing material is a decorative brick on the outer insulation finish surface.
2 Main features of inorganic thermal insulation mortar external wall insulation system 2.1 Inorganic thermal insulation mortar system for inorganic thermal insulation mortar external wall system: wall base layer, interface mortar, vitrified micro-bead inorganic insulation mortar insulation layer, anti-crack mortar composite resistance Alkali fiberglass mesh protective layer, exterior wall facing brick surface layer. See the basic structure and Table 1. Basic structure. 2 Inorganic thermal insulation mortar material properties and characteristics Inorganic thermal insulation mortar, is a surface of vitrified closed pores made of fired lava mineral material by heating and expansion, vitrified cooling, irregular spherical globular vitrified beads, anti-cracking agent, inorganic glue Coagulant and various additives, inorganic dry powder insulation prepared according to scientific ratio has the following characteristics: it has good fireproof, heat insulation, weather resistance and fire resistance performance can reach Class A standard; Effectively control quality problems such as hollow drums and cracking; it has less water absorption than expanded perlite, is not easy to incinerate, and has low shrinkage of material slurry; it has better fire resistance than polystyrene board insulation materials, and is not annoying to insects; The high strength, the pull test when using the veneer bricks can generally exceed the basic requirements of 0.4MPa, and the polystyrene board itself has low strength, it is difficult to meet the requirements of 0.4MPa; the construction is simple, the process is mature, and the quality is easy to control. 3Inorganic thermal insulation mortar insulation system construction process and characteristics of the base layer acceptance a basic treatment of a bomb thickness, verticality control line brush interface mortar inorganic thermal insulation mortar construction crack protection
Wall engineering: the screed plastering of the external wall surface is completed, and the construction quality meets the requirements of the National Standard for the Acceptance of Building Decoration Engineering (GB50210-2001), and the base of the wall is dry.
The embedded parts of the external wall surface, such as fire ladders, downpipes, inlet pipes, and exterior wall trims, have been installed without any omissions.
Door and window project: The door and window frame have been installed according to the design requirements, and the cement mortar at the side of the door and window is finished.
Table 1 Inorganic thermal insulation mortar external wall system basic structure table base wall basic structure interface layer insulation layer cover layer facing layer concrete wall and masonry wall + cement mortar leveling interface mortar vitrified micro-bead inorganic insulation mortar anti-crack mortar + resistance Alkali-reinforced mesh cloth + anchor bolt brick adhesive + tile + tile joint agent base layer should be dry, clean, oil stains, loose objects, etc. with steel brush.
If the base level is uneven, the cement mortar can be used to fill in advance.
3.4 Measurement of thickness and verticality Control vertical and square elastic thickness control line: The plastering control line shall be ejected according to the insulation thickness requirement at the side wall and the top plate.
The report of the elastic line is issued, which indicates that the protruding parts of the wall are not treated in accordance with the requirements, and the convex part of the concrete shear wall is cut out. The exposed steel bar needs to be brushed with zinc-rich primer for anti-rust treatment and the surface is brushed with HB40 rock. Together to ensure the quality of the concrete wall.
2) Punching and smashing: use the thermal insulation mortar to make the thickness of the gray cake, the spacing is less than 2m, the pulling ribs are the same, the vertical direction is the same rib, to ensure the leveling, and the pre-made polystyrene insulation board of the same thickness can be used instead of the ash cake.
Before the construction, first check the thickness, verticality and flatness of the gray cake on the wall to check the size.
During the construction, stir evenly according to the ratio, no fine particles and powder clusters. The stirred materials should be allowed to stand for 5 minutes, then stirred again, and used up within 2 hours.
The interface mortar is evenly coated twice to ensure the thickness.
The thermal insulation mortar is stirred for 35 minutes according to the ratio, so that the slurry can be used as a uniform paste. The prepared slurry should be completed within 2 hours and must not be used twice.
The construction of inorganic thermal insulation mortar for mortar painting should be applied before the interface mortar is solidified. If the interface mortar has been dried, it can be watered and wet to avoid affecting the strength of the thermal insulation mortar.
The inorganic thermal insulation mortar should be applied at least twice, and the interval should be more than 24 hours. The thickness of each painting should be no more than 15mm. When the first insulation layer is applied, firstly use the trowel to thin the insulation mortar 1-2mm on the base layer. Then paint again to a thickness of about 15mm. Generally, it is carried out after 2448 hours (depending on the ambient temperature), and then it is applied in this process every time until the design thickness is reached.
In order to ensure that the thermal insulation mortar and the anti-crack protection layer are firmly bonded, in the last construction of the thermal insulation mortar, the surface should be finely drawn and scraped to improve the adhesion.
After the final setting of the thermal insulation mortar, watering should be carried out in the summer, and the curing time is 57 days to prevent the insulation layer from cracking.
3.6 Anti-cracking protective layer and facing brick facing layer Before the construction of crack-resistant mortar, the acceptance of inorganic thermal insulating mortar insulation layer should be qualified and fully solidified before proceeding.
The crack-resistant mortar is stirred for 35 minutes according to the ratio, and allowed to stand for 35 minutes to enhance workability. Stir again before use, and no need to add water and other materials when re-stirring.
The thickness of the crack-resistant mortar is controlled at 46mm, and the thickness of the first pass is 23mm. The reinforced stencil is pressed into the crack-resistant mortar with a trowel. The saturation of the mesh mortar should reach 100°%. The alkali-resistant mesh cloth can not be reinforced. Connected, the joint is made of 160 wide standard mesh cloth at the joint, the joint is strictly prohibited from lap joint, the joint is placed in the center of the standard net, and the joint between the male corner and the corner is not less than the paving. At the same time of mesh cloth, anchor bolt reinforcement is carried out. The height is less than 30m, 4 per m2, and the height is more than 30m, 6 per m2. The corners of the corners and doors and windows are partially strengthened. The anchor bolt has an effective anchoring depth of more than 25mm. After anchoring the standard anchorage capacity of a single anchor bolt, the crack-resistant mortar is initially leveled, and the grid cloth is basically buried in the crack-resistant mortar. After 24 hours, the second road is applied, and the flatness is required. Straight, fine hair.
Check the verticality and flatness of the crack-resistant mortar layer with a 2m ruler, and control it within 3mm. After the maintenance and acceptance, the brick paving construction can be carried out.
The starting and closing parts between the heat-insulating part and the non-insulated part, such as the door and window opening, the parapet wall, the provocative lower mouth, the awning, the lower part of the air-conditioning board, etc.: pre-burying the package before the interface mortar construction Alkali-resistant mesh cloth, the width of the mesh cloth is 50mm+the thickness of the insulation layer is +100mm, and the buried width is not less than 50mm. After the construction of the insulation layer is completed, the package is turned over, and the alkali-resistant mesh cloth is turned over on the wall insulation mortar. The width is 100mm to enhance the resistance to cracking and impact.
The external wall insulation system should be combined with the façade design. The gaps should be reasonably set in the facing layer and the facing layer. The spacing of the horizontal dividing seams should not be greater than 6m, and the spacing of the vertical dividing seams should not be greater than 12m to ensure that the rain does not penetrate. Insulation layer and base layer.
The raw materials of the insulation system should meet the relevant requirements, the certificate of conformity and the test report are complete; the transportation, loading, unloading and storage should be moisture-proof, rain-proof and anti-exposure; the interface mortar, inorganic thermal insulation mortar and anti-crack mortar have a shelf life of 3 months; The alkali resistance of the mesh cloth should meet the requirements, and the sampling retest can be witnessed on site if necessary.
The exterior wall tiles shall be light, small and thin external wall ceramic tiles. The outer wall tiles used in this project are 195mmx45mm ceramic tiles, the mass per unit area is 20kg/hour, the thickness is 7mm, and the water absorption rate is <0.5%. Frost resistance > 10 times. At the construction site, the sampling and re-inspection work of the water absorption rate and frost resistance of the tile should be done well.
Face brick bonding mortar and grouting agent are important components to ensure the bonding strength of facing bricks. It is strictly forbidden to use ordinary cement mortar to paste bricks or joints. The performance of bonding mortar should meet the requirements of C/T547-2005, the performance index of jointing agent Should meet the requirements of C/T1004-2006.
The ambient temperature of the construction site and the temperature of the base wall shall not be lower than 5C, and the wind shall not be greater than 5.
The construction surface should be protected from direct sunlight for a long time, and the insulation layer and crack-resistant layer should be maintained in summer.
4.3 Bonding brick bonding strength control The bonding strength of the on-site pasting exterior wall facing bricks shall comply with the G110-2008 construction engineering facing brick bonding strength inspection standard requirements: the bonding strength of the facing brick sample parts shall be checked before construction. In this project, different base wall bases, namely concrete base layer and aerated concrete block base layer, were selected in the first room. The supervisor randomly selected one person from the construction workers who attached the facing bricks, and each paved 1m2 sample. The pull-out test was carried out after 28 days of curing, and the two sample pieces were each taken from three sets of facing bricks for bonding strength samples. The system requires that the average bond strength of each sample should not be less than 0.4MPa, and the bond strength of one sample in each group should be less than 0.4MPa, but should not be less than 0.3MPa. The bond strength of the sample is Mpa; Sample bonding - sample cross-sectional area) 5 exterior wall facing bricks falling off and prevention 5.1 outer wall facing bricks falling off causes the facing layer pasting facing bricks fall off as an inorganic thermal insulation mortar insulation system as the main quality common problem, which has long plagued the Large-scale promotion and application of insulation systems.
There have been reports of bricks falling from the sky and damaging cars, which led some local governments to issue documents to limit the use of exterior wall tiles in the building's upper floors. There are two main reasons for the falling of the tiles.
Bond strength: Even without the external insulation system, the detachment of the exterior wall tiles is a common quality problem, and the bond strength is critical. For the external thermal insulation system, the shear strength of the thermal insulation layer cannot withstand the shear stress generated by the load of the self-weight of the tile layer, and under the action of the negative wind pressure, the brick will fall off.
Weather resistance: Due to the change of temperature difference between day and night and freezing and thawing in winter, the durability of the external insulation system is destroyed. The thermal expansion coefficient of the adjacent interface of the three different materials of the exterior insulation system is larger, and the difference of the elastic modulus is also larger. It is easy to cause the interface shear stress to have a large relative deformation with the change of the temperature difference, causing the tile to fall off. .
Waterproof and breathable: A good insulation system should have good air permeability, good thermal conductivity and water resistance, but it is really difficult to do. The exterior wall tile should be covered to reduce the gap and be seamed with a grouting agent. However, it is inevitable that the lower brick will be stuck in the gap during construction. The external water penetrates into the gap of the tile, because the outer wall is not absorbent. The water accumulates in the gap, and even causes the insulation layer to pulverize after seeping water. With the temperature difference between day and night and the freeze-thaw cycle, the gap is gradually enlarged, forming an empty drum and shelling, causing serious damage.
In summary, the prevention and control of water is particularly important. The basic structure of the external thermal insulation bonding brick must be strict, and each link cannot be ignored. In order to effectively reduce the interfacial shear stress and water seepage caused by the temperature difference, the rubber layer of the facing brick should have a certain thickness, and the adhesive mortar with flexible water resistance must be used. The grouting agent should also use good waterproof performance and certain flexible hook. Sewing powder. Due to the greater lateral deformation of the flexible agent material, the lower the elastic modulus, the smaller the interface shear stress, that is, the bonding strength is improved, and the good water resistance can effectively prevent the penetration of external rain and snow water. The anti-cracking protective layer of the thermal insulation system should also be waterproofed, and a waterproofing agent should be added to the anti-cracking mortar.
In order to effectively control the problem of the outer wall brick falling off, the Ministry of Construction abolished G110-97 in 2008, released the G110-2008 building engineering facing brick bonding strength inspection standard, and added the external wall exterior insulation system to paste the exterior wall facing brick. The requirements of the seam are added, and the requirements for the standard block paste diagram with the insulation system are added. The construction unit should carefully adopt the practice of external thermal insulation paste facing bricks in high-rise buildings. Before the construction, the construction unit shall do a special construction plan, a model guide and other technical measures to implement the project under the premise of ensuring effective control.
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