Application of EPS board exterior wall insulation technology in cast-in-place concrete engineering

External wall thermal insulation technology has developed rapidly in recent years in China, especially the external thermal insulation technology of expanded polystyrene foam board (referred to as EPS board). It is one of the external insulation technologies introduced from abroad.

EPS board external wall insulation technology has good insulation effect. The insulation effect of the 60mm thick EPS board with a density of 18~20kg/m3 is far greater than that of the clay brick masonry 370mm thick wall.

Solved the thermal bridge problem. The traditional external wall temperature measures, one is to thicken the outer wall, and the other is to carry out the external wall insulation. The first measure obviously has the problem of stupid thick wall, which wastes resources; the second measure is serious due to the thermal bridge phenomenon, causing serious condensation, frosting and even frost heaving between the structural outer wall and the thermal insulation layer, reducing the inner wall surface. The life span or directly damage the inner wall.

It has a good protection for the structural external walls. Because the EPS board has good thermal insulation performance, it not only buffers the thermal conduction of the structural external wall when the external temperature suddenly changes, but also strengthens the crack resistance of the structural external wall in the high heat and cold area. Due to the influence of high heat and cold, many buildings are at the mouth of the gully, and cracks are easily generated on the wall with severe sun exposure. After the EPS board is installed, the temperature rise rate of the structural wall is slowed down, the temperature is relatively stable, and the temperature stress is greatly reduced. Therefore, the possibility of generating temperature cracks is greatly increased.

Increased the use area of ​​the building.

The EPS board is a foamed plastic panel composed of a completely closed honeycomb polyhedron. The honeycomb has a diameter of 2 to 5.5 mm and the honeycomb wall thickness is O. OOlm. The foam is composed of about 98% air and 2% polystyrene. It is the unique structure inside the EPS that makes the air completely enclosed in the honeycomb a good insulator. The thermal insulation properties of an EPS board depend entirely on its density. According to the relevant information, when the density is 3050kg/m3, the thermal conductivity is minimized. When the temperature is 10, the thermal conductivity is 0.0290.033W/(mk)D. The most used in domestic construction engineering design is density. For the 18~20kg/m3 plate, the thermal conductivity is relatively high, 0.013~0.036W/(mk), but it is much more economical than the 30~50kg/m3 sheet.

3 auxiliary material expansion bolts. At present, the expansion bolts commonly used in engineering, the chrome (zinc) rod with a screw length of 110 mm, the expansion tube is a nylon tube, and the reinforcing cover is a nylon cover with a diameter of 70 mm.

Glass fiber mesh cloth (referred to as mesh cloth). It is a reinforcing material for the outer wall insulation layer and has strong alkali resistance. The elongation of the mesh cloth should be as low as possible so that it does not wrinkle when applied. The elongation should be controlled between 3% and 5%. The mesh size of the mesh cloth is also very important. When the side length of the mesh is 3.5~5nim, it can be used to paste the mortar into the mesh during the pasting process, and the shrinkage stress of the surface mortar can be evenly distributed. Apportioned to the grid.

Polyphenyl anti-cracking mortar. It consists of a certain proportion of colloid, cement, short fiber and medium sand.

4 Construction and construction process: lashing the outer wall, column steel bar - installing EPS board - upper expansion bolt - vertical vertical formwork 4 pouring concrete - processing door and window opening, deformation joint - doing wall surface division part paste mesh cloth strengthening wipe Once again, the polystyrene crack-resistant mortar - pressed against the mesh cloth - wipe the second pass polyphenyl anti-crack mortar.

Lash the outer wall and column reinforcement. It is required to tie the forming steel bar, the outer wall surface is vertical, flat, and the knot is upward or downward, and the plane is not warped. The pad area of ​​the steel protective layer is slightly larger than usual, and the distribution is even and cannot be leaked.

Install EPS board. The EPS board must be arranged in advance according to the designed floor height, facade shape, and the like. The plate thickness currently used is 60mm in Beijing. Since the EPS board is installed, it takes a long time to cover the surface of the EPS. In order to resist the ultraviolet radiation, the EPS board must be evenly surfaced before leaving the factory. Spray a layer of anti-UV glue. The EPS board must also be spaced apart from the groove on the side of the concrete surface. The goal is to make the board more firmly bonded to the cast-in-place concrete. The groove depth is generally lmm, the groove width is 100mm, and it can be opened into a flat groove or a dovetail groove. In order to connect the adjacent sides of the board, the periphery of the board should be opened into a tongue.

The loading plate should start from the negative or positive angle. The yin and yang slats can be shaped according to the design requirements. The width of the gusset flange depends on the wall condition, generally 200~300mm. The relative independence of each wall panel is installed from the deformation joint, the middle of the window partition, and the like. The bonding of the seams uses a special adhesive for the EPS board. First apply glue to the finished board, then apply glue to the joint of the board to be installed. After a little drying, paste the two boards together.

After the EPS board is installed with a relatively independent panel, it is perforated with a steel brazing material at a suitable location, and the EPS board is attached to the steel mesh panel by passing the wire from the hole. When tying, it is not advisable to be too tight. The steel mesh and the EPS board can move slightly to avoid over-tightening. If the external force is slightly affected, the board will be broken or the EPS board will be deformed. After the EPS board is fixed, wear the expansion bolts. The expansion bolt should be pre-screwed into the expansion tube, so that the end of the expansion tube is flared, and the perforation is rotated by a steel with a taper of 1:7 or larger than the diameter of the expansion bolt, and then the expansion tube is inserted into the hole. The tying wire tied the bell of the tube and tied it to the mesh.

Close the mold. Lightly press the wall template against the EPS board, pierce the bolt hole position by the above method, and then wear the pull bolt and the bushing (do not mix debris between the template and the EPS board), just like the ordinary mold , tighten the template and fix the position.

Pouring concrete. When pouring concrete, the height difference of the first wall concrete should not be too large, so as to avoid pushing or destroying the EPS board due to the height difference of the concrete. Do not allow the vibrating rod to directly vibrate the EPS board.

Modification. The hole that appears on the wall of the EPS board after demoulding must be refurbished. It is a big problem related to the success of the entire outer insulation. 1 exterior door, window renovation. Since the EPS board cannot be installed at the same time as the formwork during concrete construction, the insulation board here must be pasted after the mold is removed. 2 repair of the gap and the hole. Cut the gap and reserved hole in the construction into a rectangle with a side length of not less than 60mm (depending on the size of the original hole), and then repair it with polystyrene mortar (the ratio of polystyrene mortar is: mortar: granule) =1: 0.7 (weight ratio)). Repair to make the hole full, the surface is flush with the surrounding polystyrene board. If there are holes and gaps filled with concrete, the concrete of the holes and gaps should be removed and cleaned with polystyrene granules as described above.

Verticality and flatness control. The control of the verticality generally depends on the verticality of the structural construction. When the structure is required to be constructed, the verticality of each layer shall not exceed 5 mm, and the vertical deviation between the layers shall not overlap. In this way, the polystyrene mortar can be controlled to a thickness of 5 mm at the thinnest part and a thickness of about 10 mm at the thickest point. If there is a partial stagger between the EPS boards, use a special brush to flatten them.

The wall is divided into seams. The wall joints can be divided according to the architectural design and construction drawings. The width of the general joints is 12~20mm and the depth is 8~10mm. When the last polystyrene mortar is finished, the joints are popped on the surface. Embed a grid of stripes on the seam. Installed grids should be straight, flat, and labor-intensive. The grid strips shall be pressed into the grid joints on both sides, and then the polystyrene strips shall be used to adhere, stick and smooth the sides of the grid strips.

Polystyrene mortar is generally provided by the EPS board manufacturer, and a high-strength short fiber is added to the mortar, and the effect is better. After the mortar reaches the site, according to the proportion of the instructions, the mortar can be mixed on the wall to be applied to the wall. The construction procedure is to wipe the mortar once, apply a layer of mesh cloth, and wipe the mortar again. The base layer must be cleaned before the first pass of the mortar, leaving no oil stains. The thickness of the polystyrene crack-resistant mortar in the first pass is about 3mm. The mortar should be spread evenly and the thickness is the same. When the mortar is slightly dry (but still wet), the alkali-resistant mesh cloth is pressed into the mortar with a trowel. The cloth shall not be exposed to the mortar surface and shall not be beaten while pressing. When the mesh cloth is paved, it should be stretched without wrinkles. When it meets the edge and the seam is to be reversed, the overlap length of the reverse wrapping width >60mm mesh cloth is generally 60~80mm. Waiting for the first sand The wedge thickness is 矣3mm), so that the mesh cloth is completely covered. The surface treatment of the second mortar is divided into two cases: the surface is directly painted, and the surface of the mortar should be calendered; when the surface is made of a block, the surface of the sand should be bristled. Strengthen the mesh cloth before the first pass of polystyrene mortar construction, and paste with polystyrene glue.

5 Quality assurance measures In the deformation joints, division joints, and the edges of various holes, the polystyrene glue must be used to block the joints to avoid frost heaving after entering the water, so that the insulation system is destroyed.

There must be a 5mm gap between the perimeter of the door and window frame and the EPS board, and the appliance and the elastic sealing glue are tightly sealed. If you do not leave a seam, in fact, there will be thin seams, but the plugging will not be strict, and there will be a seepage channel, causing a breach of the breach.

When constructing the structure, it is necessary to control the verticality of the wall surface. Otherwise, a very thick polyphenylene mortar will be applied to find the vertical, so that the mortar surface is easy to crack. The verticality of each layer should be strictly controlled, and no deviation should occur.


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