Causes and Prevention of Leakage of External Wall
The quality level of construction projects has been somewhat improved. The complaints about housing quality in the society have also increased. The external wall leakage accounts for a certain percentage, but it has caused great inconvenience to the residents' normal lives and use. According to the author's experience in the maintenance of housing quality over the past few years, I talked about my understanding and practical experience in this area.
First, the analysis of the causes of wall leakage:
1. The current infilling walls of framed residential projects are basically non-bearing sand-lime bricks or small blocks. Lime and sand bricks and small blocks are prone to damage during transportation and construction, and are free from defects such as corner dropouts. If the use of damaged or dark pipe fittings in the construction of the equipment must be chiseled, artificially caused damage to the external wall masonry, it is also easier to form a water seepage at the external wall masonry.
2. The workers did not strictly follow the construction specifications during masonry construction and the masonry mortar was not full, especially the vertical joint mortar. In addition, the strength of the mortar does not reach the standard or dry brick wall, so that the moisture in the mortar is absorbed by the brick, resulting in a low strength mortar, resulting in the separation of brick and mortar, the overall stiffness of the masonry decreased, resulting in wall cracks.
3. The temperature difference leads to the cracking of the joint between the concrete structure beam column and the infill wall.
4, the outer wall plastering layer is too thick at the same time or in order to ensure the full height of the vertical partial thickness, and did not take appropriate measures to strengthen the cracks; wall surface is too smooth, bad combination; large outer wall The area was underlayed and the base line was not lined, resulting in irregular shrinkage cracks.
5, empty brick or paving mortar facing brick is not full, the gap between the brick and mortar is easy to form a water storage container; brick joints are not dense or cracking joints, joints missing joints are to make the rain from the surface infiltration , causing water accumulation, causing leakage. In addition, there is a certain relationship between the wall seepage and the brick seam and the unevenness of the surface of the tile. The concave joints make the whole wall of the external wall not smooth, the rainwater flow rate is slowed down, the water stagnation time and the water stagnation increase, especially at the lower edge of the jointing. Stitching quality is unsatisfactory or long-term wind and rain cause micro-cracks between joints and tiles, causing leakage.
6. No slope or slope is found in the surface construction of horizontal components such as window sills, sun visors, and awnings, which may result in returning water or accumulated water, and it may easily cause water seepage on the external walls.
Second, external wall leakage prevention measures:
1. The bricks used for the masonry of the outer wall shall be provided with a wide range of edges and corners to improve the waterproof capacity of the masonry and shall not be broken during the masonry process. When the length of the wall does not match the number of bricks, Insufficient modulus is adjusted by solid bricks or primes. The masonry of the external wall shall be avoided as far as possible when the masonry is finished. If there is a prefabricated submerged pipe, the joints may be left in advance on both sides of the installation pipeline, and the joints shall be pulled and rebared at intervals of 600mm vertically. The ribs extend into the wall of 250mm, and are piled and poured with C20 fine stone concrete. At the same time, the defects of the wall caused by scaffolding eyes, cable holes, etc. must be repaired before being painted, leaving no hidden trouble.
2. Construction technicians should provide technical disclosure to workers and strengthen spot checks. It is forbidden to dry the bricks on the wall, strictly control the mix ratio of the mortar, ensure the fullness of the mortar, and horizontally lay the mortar over the horizontal joints. Carefully fill the grout with a hooking trowel to ensure the quality of the external vertical joints. The sloping joints above the inclined roof shall be inspected on the outer wall operation frame 3 days before the plastering. If the hooks are not hooked and cracked, they shall be filled. The deep cracks shall be kicked out with a width of not less than 10mm. Seams to ensure that the heavy hooks are filled.
3, cracks caused by temperature difference, first of all, should crack the bottom of the cracking chisel, plus wire mesh, and then high-grade cement mortar layered and solidified, and pay attention to conservation, and then the surface layer construction, can effectively prevent The cracks are generated to reduce the leakage of the wall. The phenomenon of cracks under the top window, vertical cracks under the window, etc., can be used to increase the stiffness and eliminate cracks by adding a long reinforcement bar at the top window sill to close the top window plate.
4, for the grass-roots cracks, we must first ensure that the base of the outer wall should not be too thick, to the local thick to strengthen the use of steel mesh, followed by the outer wall should be sub-divided, stratification, rendering before the final condensation to prevent Exposure or rain, strengthen conservation. Do a good job of dividing line, especially in the decorative surface for the non-lined tiles, mosaics and Other walls should also be placed in place in the appropriate part of the grid line, with ointment after caking, before the upper layer. Thirdly, for a relatively smooth structural layer such as a concrete column and a beam, the polymer mortar is used for “grossing†treatment (the ratio of the polymer mortar can be 107 glue:water:cement:sand=1:4:10:10 and the mixing is evenly measured. ), coated on a smooth surface layer, wet curing 7d, so that the "growth" to enhance the adhesion, and then fully back to the bottom, to avoid hollowing, poor bonding and other defects.
5. For the building with external wall tiles, technical disclosure must be made in advance before the construction of the external wall. In the process of paving, there must be squeezing process, and thoroughly check the condition of emptying before jointing. The degree of compaction should be ensured during the jointing. After the jointing is completed, we should pay attention to moist curing. The joints must not be missed. It is recommended to strictly control, concave degree should not be too large, it is best hook into a circular flat seam. Quality management should establish a multi-level review control system to ensure the quality of each procedure.
6. Horizontal components such as window sill, sun visor and awning shall be slope-sloped and slope-finding direction shall be correct according to the requirements. The contact with the wall surface shall be treated as a pan-water arc angle to prevent pouring of water or stagnant water. The perimeter of the window frame should be raised and glued. After the window, the fortress should be tightly closed. The drip groove should be made above the window hole (the depth and width should not be less than 10mm). During the construction of the roof, special attention should be paid to the root position of the girl's wall and the wall should be poured 10-15mm more than the roof to ensure that the root construction joint of the daughter's wall is higher than the roof, and then the wall of the parapet is built, so even if the construction joint is tiny The cracks will not cause root leakage of the daughter's wall, ensuring the appearance of the building.
7, 2 kinds of new materials can be used to prevent the leakage of the external wall: 1 In the external wall plastering cement mortar by adding Dura fiber; 2 using waterproofing leak-proof color caulking material for external wall tile caulking. Compared with plaster cement mortar without Gadura fiber, its crack resistance is increased by more than 80% and impermeability is improved by more than 60%. Mixing cement mortar, the original mixing equipment and technology, mixing ratio unchanged, the mixing time is not less than 3min and visual observation of the bundled fiber is not accurate, the amount of dura fiber considering packaging (1kg / bag) and Mortar machine capacity (200L), taking 0.714 kg/m3, is divided into 7 packets per packet, 1 packet per slot. Plastering mortar cement construction, according to conventional methods of construction. Before plastering, add 300mm wide mesh wire mesh at the junction of beam bottom and wall column. After the surface of cement mortar put on the surface is dry, grind the surface with wooden trowel and pure cement slurry. After the cement mortar is solidified, it is poured. Water conservation for 1 week. Water-proof and leak-proof color caulking material adopts black tile caulking material produced by Foshan Jianneng Material Factory. Its product performance has been tested. The bending strength is 6.4MPa, the compressive strength is 30.8MPa, the water absorption rate (24h) is 5.1%, and the water seepage rate is 0.293 . The requirements for the construction conditions are: After 24h of external wall tiles are glued, the seam width is 5-15mm, the mixing ratio is 1:3, and the well-mixed caulking compound is allowed to stand for 5 minutes before use. And it should be used within 3 hours; about 20 minutes after caulking, the surface of the external wall should be cleaned, and the joints should be repaired incompletely. The above two kinds of new materials are applied in actual construction, and the seepage prevention effect can achieve the intended purpose, and the operation is simple, safe and convenient, and has a wider application prospect.
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