What are the preventive measures for common quality problems in construction?

It is very important to take preventive measures against common quality problems in construction. Only by understanding the measures can we make a better plan, and the handling of every detail is very important. Zhong Da Consulting will explain the preventive measures for common quality problems in construction projects.

(1) Foundation

(1) Check the pouring cushion in time after foundation excavation.

(2) Backfill and fill in layers, test the compaction coefficient of each layer, and fill the upper soil after checking that it meets the design requirements.

(3) Backfill soil is cohesive soil, and miscellaneous fill soil and domestic garbage shall not be backfilled.

(4) When backfilling, pay attention to protect the waterproof layer of basement exterior wall. Backfill by hand and tamp by layers.

(II) Major projects

(1) In order to prevent water seepage from window corner cracks, it is required that the outer window sill plate be made into a concrete strip with a thickness of not less than 90mm, and there are three φ8 long ribs with a spacing of not more than 250mm, which are welded into a net and placed in the middle of the strip, and both ends are effectively anchored with constructional columns. The concrete strength grade is not less than C25.

(2) In order to reduce the cracks in the top wall of residential projects, the top wall should be uniformly provided with full-length cast-in-place reinforced concrete strips on both sides of the window sill, the lintel at the door and the wall without doors and windows, with a thickness of ≥80mm or more, with 3 Φ 8 long steel bars and distribution bars of φ8, and the spacing is not more than 250 mm.. Should be spot-welded into a net and placed in the middle of the strip, its two ends should be effectively anchored with the constructional column, and the concrete strength grade should not be lower than C20.

(3) In order to prevent cracks in the cast-in-place slab, five φ8 radial ribs are added to the large-angle cast-in-place slab of the external wall, and the length is not less than1500mm; ; For the overlapping parts of electric tubes with a diameter greater than 30mm and two or more layers of electric tubes, steel mesh should be added locally, or double-layer two-way stiffeners should be set on the plates where individual electric tubes are concentrated. The width of the mesh should be determined according to the direction and scope of the electric conduit. Generally, the spacing between steel bars should be not less than 500mm, and the specifications should be consistent with the plate steel bars.

(4) Effective measures must be taken to ensure the thickness of the floor and the thickness of the protective layer of steel bars in the floor. Below the negative bending distance of cantilever cast-in-place slab such as balcony awning, a protective layer pad of reinforcement with a spacing of not more than 300mm shall be set, and measures must be taken to ensure that the reinforcement does not shift when pouring concrete.

(5) When the template isolation agent is painted, it is not allowed to pollute the steel bar and concrete joints.

⑥ Before concrete pouring, the position of construction joints and the lien position of post-cast strip shall be determined according to the design requirements and construction technical scheme.

All landowners without the consent of the design, shall not dig a wall or dig a horizontal slot in the wall.

When laying brick masonry, the brick should be watered and wetted in advance 1 ~ 2d. The daily masonry height should not exceed the scaffold height or1.5m.

Pet-name ruby infilled wall build by laying bricks or stones to close to the bottom of the beam, plate, should leave a certain gap, after being infilled wall masonry, should be at least 7d interval, in build by laying bricks or stones to compaction.

Attending the Rachel reinforcement position retained by the infilled wall masonry should be consistent with the number of blocks. Rachel reinforcement should be placed in mortar joint, the buried length should meet the design requirements, and the vertical position deviation should not exceed one brick high.

(3) Decoration works

(1) All the inner sides of external walls are made of mortar, and concealed acceptance shall be made as required;

② The setting time and stability of cement must be reinspected in plastering project, and medium coarse sand should be selected and screened during construction; Mix plastering mortar in strict accordance with the mixture ratio, and the field measurement shall be strictly controlled by special personnel; The base of concrete beam and column is treated with concrete interface agent to ensure the combination of base and painting layer. Before plastering the wall surface, the grass-roots treatment and watering should be done well, and the isolation agent and sundries on the concrete surface should be cleaned up.

(3) The plastering thickness of each layer (base layer and surface layer) shall not exceed the thickness stipulated in the specifications and procedures. When the total plastering thickness is greater than or equal to 30mm, it must be reinforced with mesh, and it is forbidden to survive again. The ash layer should not be too tight. After the plastering layer construction is completed, water shall be sprayed immediately.

(4) The most effective method for concrete slab bottom is not to plaster, strictly control the quality of cast-in-place slab, especially the flatness and template flat-fell seam, and directly polish, batch putty and paint the slab bottom;

⑤ The grade of ground cement mortar should not be too low, and the grade of plastering mortar should generally not be lower than 1: 2.5. During construction, the calendering time should be well controlled and medium-coarse sand should be selected. Cement floor shall not be sprinkled with dry ash or sprinkled with water to collect light during trimming; After the floor survives, the finished products must be protected, and walking and construction on the newly completed cement floor are not allowed. After plastering, the surface should be watered and maintained in time.

(4) Prevention of roof leakage

In order to prevent the leveling layer from cracking and hollowing, after the base is cleaned, the leveling layer should be carried out immediately after the final set of concrete at the base; At the same time, control the setting of frame joints and calendering time, and cover the leveling layer in time after final setting. Control the drainage slope of the gutter to make the drainage smooth. The construction quality of roof pipes, flues, eaves gutters and parapets should be strictly controlled to prevent water accumulation around them. At the junction and corner of the base and protruding roof structure, the leveling layer should be made into an arc. A waterproof measure should be added to the place where water leaks easily here.

(5) the kitchen, bathroom leakage prevention

During structural construction, the cast-in-place floor slab of kitchen and bathroom is 40-50mm lower than that of other indoor rooms. Ensure that the coordinate position of the reserved hole is correct and avoid digging holes; The present situation of reserving holes for large reserves and small reserves. The smooth outer wall of the upper and lower water pipes passing through the floor should be chiseled, and then a layer of 404 plastic glue should be evenly coated, and then the medium and coarse sand should be evenly sprayed. The joints should be poured with HLC anti-cracking and impermeability agent (70% of cement dosage) and fine stone concrete twice. After the construction of waterproof material for kitchen and bathroom floor is completed, the water storage test should be done seriously. The water storage depth is 20-30mm, and it is qualified if there is no leakage for 24 hours, and the concealed acceptance record shall be made.

(6) External wall surface leakage prevention

(1) Before painting, repair the wall surface, fully water and wet the foot and hand holes, and repair the inner side with half brick first; The outer side was repaired twice with high-grade fine stone concrete. 1-2d metope should be fully watered and wet before painting, and the mortar should be leveled in strict accordance with the mixture ratio. The exterior wall coating should ensure the coating quality, and give priority to the exterior wall coating with fine particles, strong adsorption, alkali resistance and washing resistance, so as to better seal the decorative plastering surface of the exterior wall and improve the impermeability of the exterior wall.

(2) The fineness modulus of sand for exterior wall painting should be greater than 2.5.

(7) window frame leakage

1. The window was made in the factory. After entering the site, the product certificate shall be provided, and its specification, model, production size and drainage hole position shall be accepted.

2. Before installation, random sampling shall be sent to testing institutions to test its technical performance indicators such as air tightness, water tightness, wind resistance and strength. Only after obtaining the qualified test report can it be used.

3. The position of the reserved hole in the window should be correct, and the gap between the window frame and the wall should be even, controlled at 20-30 mm ..

4, window frame and the hole should be elastic connection is firm, window frame shall not be directly buried in the wall.

5, window frame fittings and the mouth of the cave should be reliable connection. The connector shall be fixed outside the window frame. When setting, the upper and lower ends of the edge are set at the point of 180mm, and the interval between them is not more than 500 mm.

6. The windowsill slab fine stone concrete is formed by qualitative formwork at one time to ensure the consistency of concrete density and thickness and meet the design requirements and specification requirements.

7. When polyurethane foaming agent is applied around, it should be connected evenly without swelling. It is forbidden to cut with a knife, and the outside is sealed with waterproof sealant to ensure the appearance.

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