Guidelines for the Prevention and Control of Common Quality Problems in Residential Project Leakage and Cracks (2017)

Guidelines for the prevention and control of common quality problems in leakage and cracks in residential projects

First, the external wall leakage prevention and control measures

1. Before the external wall is plastered, all kinds of incoming pipelines, air conditioning pipe holes, water drop pipe fixings, lightning protection leads and air conditioning brackets on the wall body should be installed according to the design requirements, and the gap should be left according to the thickness of the external insulation system. The above contents should be specially inspected and accepted, and a hidden project acceptance record should be formed.

2. The pipe through the outer wall should be casing, the casing should be high inside and low outside, the slope should not be less than 5%, and the casing should be closed with neutral silicone weathering sealant.

3. The external wall should be reliably blocked by the pull bolt hole, scaffolding tie knot and scaffolding eye. When sealing scaffolding eyes and holes, they should be cleaned, moistened with watering, and then tightly sealed with dry hard fine stone concrete. The bolt hole through the wall should be first filled with polyurethane foaming agent, and then filled with waterproof expansion dry hard cement mortar, the filling depth is not less than 50mm, and the outer surface of the hole should be waterproofed three times after sealing, and a hidden project acceptance record is formed.

4. The surface of the wall must be leveled by overall plastering before the construction of the external insulation project (the on-site polyurethane foam external wall external insulation system can not be plastered, but the interface treatment of the grass-roots wall is required). The junction of the filling wall and the concrete should be nailed according to the requirements of the hot-dip galvanized welded steel wire anti-cracking mesh, the mesh size should not be greater than 20mmх20mm, the diameter of the steel wire should not be -2-less than 1.2mm, the steel wire mesh should be fixed with steel nails or nails plus iron sheets, and the spacing should not be greater than 300mm. The width of the anti-crack net and all kinds of basic layer overlap should not be less than 100mm. Mortar bonding layers are made on the surface of the outer wall and wet with watering before the external wall plastering can be carried out.

5. The exterior wall screed plaster mortar should be made of micro-expansion waterproof mortar mixed with waterproofing agent, and the thickness of the plastering screed layer is greater than or equal to 35mm when the thickness of the plastering layer is greater than or equal to 35mm, and the strengthening measures of anti-cracking air defense drums such as hanging nets and layered plastering should be taken.

6. Protruding out of the outer wall surface of the eaves, awnings, air conditioning partitions, etc. should be poured at the same time as the wall, the plate surface is set up with a drainage slope of not less than 2%, and according to the design requirements to do a good job of waterproof treatment, when the design is not required, the board surface should add no less than a flexible waterproof layer, waterproof angle treatment and flood height should meet the requirements of the specification, to eliminate leakage to the room at the yin angle.

7. The bottom of the part that protrudes out of the wall with drainage requirements should be drip line, and there must be no climbing water and poor drainage. Drip lines should give priority to the finished drip line (groove), if the eagle beak or large slope drip line is used, the slope of the large slope should not be less than 10%.

8. Before the construction of the external wall insulation project, the same materials and processes should be used at the construction site to make a model wall, and the construction, supervision and construction general contracting unit shall check that it meets the requirements and report to the quality supervision agency of the place where the project is located to confirm the construction.

9. When the components protruding from the wall are constructed in the insulation layer, the principle of pressing the side above and the side pressing below should be followed to avoid the occurrence of seams in the sky. If the external wall insulation layer needs to be divided into seams, the location and treatment measures should be clarified by the design unit.

10. The exterior wall coating (true stone paint) finish should be made of flexible water-resistant putty and high elastic paint compatible with the insulation system. After the completion of the construction of the real stone paint screed putty, a closed primer should be applied.

11. Curtain wall and structural closing, external wall decorative closing, door and window frame around the external wall contact, pipeline and equipment support through the insulation board, wall top closing, etc., in the gap combined with the insulation layer should take reliable measures and do waterproof sealing treatment.

12. Straight pipes should be set up at the protruding parts of the wall surface such as the air conditioning plate and cornice line through which the water drop pipe passes, and the gap or hole should be reserved, and the casing should be provided when the hole is reserved; when the elbow must be used to bypass, the joint angle of the elbow should be obtuse angle.

13. The construction unit shall organize the construction and supervision units to conduct water tests on all external walls, and make inspection records and retain image data.

Second, the external window leakage prevention and control measures

1. The construction contract of the door and window project should clarify the quality standards. The professional construction unit of doors and windows shall deepen the design of the details and structure of doors and windows according to the design requirements, prepare a special construction plan for doors and windows projects, and submit it to the construction, design, construction general contracting and supervision unit for review.

2. After the doors and windows enter the site, the construction, construction, supervision units should carry out joint acceptance, verify the consistency of the quality certification documents with the physical object, and check the quality of the doors and windows, and after meeting the requirements, witness sampling in accordance with the regulations, and re-examine the air tightness, water tightness, wind pressure resistance and thermal conductivity, etc., and can be used only after passing.

3. The installation of doors and windows must be firm. When using hollow bricks and lightweight blocks as masonry materials, the fixed position of doors and windows should be constructed with solid concrete blocks or solid bricks. Installation of doors and windows on masonry is strictly forbidden to be fixed with projectile nails.

4. The construction general contractor shall accurately retain the doors and windows and openings. For holes that do not meet the requirements, the repair thickness of more than 35mm should be reinforced with reinforcement mold pouring C20 or more fine stone concrete repair, and the repair thickness of less than 35mm should be used polymer mortar layered plastering. Door and window special -4- the owner of the construction unit should prepare the door and window sample drawings, and the opening according to the sample drawings to check one by one, the hole location, size, verticality in line with the specifications and installation requirements, the construction general contracting unit and the door and window installation unit to handle the handover acceptance procedures.

5. The installation of external doors and windows should be equipped with a frame. The material, variety, specification of the frame, the connection method between the frame and the structural opening, the anti-leakage and other structural measures should be specified in the design documents, and there is a node detail. The frame and the opening, the window frame and the frame should be sealed with neutral silicone weathering sealant, and the frame installation should be accepted as a hidden project.

6. The outer doors and windows around the opening should be flattened with micro-expansion waterproof mortar mixed with waterproofing agent, and then the frame can be fixed.

7. The root of the outer window sill should be increased with self-adhesive waterproof membrane or coated waterproof material. The outer window sill should make an outward flowing water slope, the slope is not less than 10%, and the inner window sill should be higher than the outer window sill by 10mm. The drip line (groove) of the top of the door and window should be given priority, and if the eagle's beak or large slope drip line is used, the slope of the large slope should not be less than 10%.

8. The frame under the window should be installed and fixed by the fixing sheet method, and it is strictly forbidden to use long-legged expansion bolts to penetrate the profile to fix the door and window frames. The fixed piece should be galvanized iron sheet, the thickness of the galvanized iron sheet should not be less than 1.5mm, the fixed point spacing: 150 ~ 200mm at the corner, and the edge of the frame is not more than 500mm. After the window side and top surface are punched, the process hole cap should be sealed with sealant before installation.

9. The patchwork material of the combined outer window should be connected by socket or lap, and should be extended into the upper and lower base layers of not less than 15mm. The splicing should be spliced with glue, and the outer seam should be sealed with sealant. The connection part of the frame fan member and the assembly part of the hardware should be sealed with a sealing material. -5-Member connection should be connected by notch and mortise to ensure that the corners are dense and the junction seams are full of sealant. The gap between the boxes is not more than 0.1mm and is crowded with sealant, and the connection screw fixing point between the box and the box must be sealed with sealant. The sealing strip should be made of THERMOPLASIC elastic seals such as EPDM rubber, neoprene rubber, silicone rubber and so on. Sliding door and window frame fans should be sealed with siliconized plus pieces of wool, and the sealing rubber strips and sealing tops should be continuous to form a sealing structure around them.

10. The location, quantity and specifications of the drainage holes of the outer doors and windows should be set according to the type of doors and windows to meet the drainage requirements. Drainage holes should be set up in the sills under doors and windows to ensure that there is no water in the retaining tank, and the spacing between drainage holes is not more than 1m, and not less than 2.

11. The gap between the outer door and window frame and the opening should be filled with polymer cement waterproof mortar or foamed polyurethane. When filled with foamed polyurethane, a special limit should be set to ensure that it does not overflow outside the frame, and the foam should be formed at one time, filled and full, and must not be cut.

12. The outer door and window frame should be surrounded by neutral silicone weatherproof sealant, and should be completed before the exterior wall painting paint, the glue should ensure that the base layer is dry, no cracks, bubbles, smooth corners, tight. When the outer doors and windows are aluminum alloy doors and windows, the inside of the door and window frames should also be sealed.

13. After the installation of external doors and windows, the insulation layer or the external wall finish construction is closed, the installation quality should be concealed engineering acceptance, and a record should be formed.

14. After the installation of external doors and windows is completed, the construction unit shall organize the construction, supervision, and door and window installation units to conduct water tests on all external windows, and make inspection records, and retain photos and video materials for archiving.

Third, the bathroom floor leakage prevention and control measures

1. The waterproofing project construction contract should clarify the quality standards. The waterproof professional construction unit shall deepen the design of the details and structure according to the design requirements, prepare a special construction plan for the waterproof project, and report it to the construction general contracting unit, the supervision unit and the construction unit for review.

2. After the waterproof material enters the site, the construction, construction and supervision units should conduct joint acceptance, verify the consistency of the quality certification documents with the physical object, and check the appearance quality of the material, and after meeting the requirements, witness sampling according to the regulations, and use it after passing the sampling inspection.

3. The concrete of the bathroom floor slab should be poured at one time and vibrated densely. Around the floor slab, in addition to the door opening, there should be cast-in-place reinforced concrete on the platform, and poured at the same time as the floor slab, the height is not less than 150mm. The perimeter of the exhaust (smoke) duct reserved opening should be turned up to a cast-in-place concrete retaining platform with a height of 150 mm and a width of 50 mm, and poured at the same time as the floor slab.

4. The water stop section should be given priority at the place where the pipeline passes through the floor. When the reserved opening is adopted, the coordinate position of the reserved opening such as the water supply and sewerage pipes and exhaust (smoke) channels should be correct, and the shape of the opening is large and small. Before the opening is sealed, the side wall of the cave should be chiseled, and the opening should be cleaned, watered and moistened, and brushed with glue cement slurry as a bonding layer, and the bottom is supported with a template, and the template should be fixed firmly and must not sag. When sealing the opening of the cave, the strength should be increased by one level, and the fine stone concrete mixed with micro-expander is poured and pounded in two batches, and the first pour is 1/2 of the thickness of the floor slab, and then poured to the surface of the floor slab after reaching a certain strength. After the opening of the hole is sealed, a 24-hour water containment test should be done at the root of the pipeline to ensure that there is no leakage before the next process is constructed.

5. Through the root of the floor pipe should be set up a water barrier platform, and the water barrier platform should not be directly on the ground surface layer, the height of the water barrier table should be reserved in advance, to ensure that the higher than the finished ground is not less than 20mm.

6. The leveling layer should be flat and smooth, and the pubic corners should be smeared into small arcs. When applying the waterproof layer, the base layer should be cleaned, and the upper return height should meet the design requirements and not less than 300mm. The root of the pipe, the root of the exhaust (smoke) channel, the root of the wall and other parts should be made as waterproof additional layers.

7. For the water supply and heating pipes laid along the ground, at the entrance to the bathroom, it should be raised along the outside of the bathroom partition wall to the height of the waterproof layer, and then enter through the partition wall to avoid damaging the waterproof layer.

8. When the toilet is used as a bathroom, the waterproof layer of the wall shall not be less than 1800mm; the waterproof material at the entrance of the door should be extended to 300mm wide.

9. The difference between the ground surface layer at the entrance of the bathroom door and the ground surface layer of the connected outdoor room should meet the design requirements and should not be less than 15mm. The slope of the floor of the bathroom should meet the design requirements (1% to 1.5% when the design is not required), and the elevation of the floor drain installation should be 3 to 5mm lower than the adjacent ground, and there shall be no pouring water and stagnant water.

10. The bathroom should do a water storage test, at least once when the construction of the waterproof layer is completed, once when the waterproof layer is completed, the water storage time is not less than 24 hours, the water storage height is not less than 20-30mm, and do a good job of inspection records, keep photos and video data for archiving. Water should also be stored during pre-completion inspections (except for winter construction).

Fourth, roof leakage prevention and control measures

1. The construction unit of the roof waterproofing project shall organize the drawing review before construction, and shall not change the roof waterproofing grade and waterproof material without authorization, and if it is really necessary to change, it shall be reviewed and approved by the original construction drawing review body. For the daughter wall, high and low spans, upper manholes, deformation joints and out of the roof pipe, well (smoke) road and other nodes should be designed anti-seepage structure details, out of the roof well (smoke) around the perimeter should be poured together with the roof structure of a reinforced concrete waterproof circle.

2. Roof waterproofing must be constructed by professional construction units with corresponding qualifications, and the construction contract should clarify the quality standards. Professional construction units should deepen the design of details and structures according to design requirements, prepare special construction plans, make construction models, and report to the general contractor, supervision, and construction units for review before construction.

3. After the waterproof material enters the site, the construction, construction and supervision units should conduct joint acceptance, verify the consistency of the quality certification documents with the physical object, and inspect the appearance quality of the materials, and after meeting the requirements, witness sampling according to the regulations, and use them only after passing the sampling inspection.

4. The drainage slope of the screed layer should meet the requirements. The slope of the flat roof using the structure should not be less than 3%, the slope of the material should not be less than 2%; the longitudinal slope of the gutter and the cornice should not be less than 1%, and the water drop at the bottom of the ditch shall not exceed 200mm. At the junction and corner of the base layer of the membrane waterproof roof and the daughter wall, gable wall, skylight wall, deformation joint, smoke (well) road and other protruding roof structures, the leveling layer should be made into a circular arc of not less than R50. Slightly lower pits should be made around the water drops for internal drainage.

5. The insulation layer of the inverted insulation roof should adopt insulation materials with low water absorption and long-term immersion without deterioration.

6. The paving of the plate-like insulation material should determine the paving direction according to the calibration slope line, and the paving and filling seam should be carried out in layers and segments. When paving, the gaps between the upper and lower plates should be staggered with each other, and the thickness of the two adjacent plate edges on the surface is consistent. After the construction of the insulation layer is completed, the leveling layer should be laid in time to reduce moisture and water ingress, especially in the rainy season, and measures should be taken in time.

7. The exhaust pipe should be set on the structural layer, vertical and horizontal penetration, not blocked, the spacing should be 6m, and communicate with the exhaust port connected with the atmosphere. Through the insulation layer of the pipe wall should be equipped with a vent hole to ensure the smooth flow of the exhaust pipe, the roof area every 36m2 should be set up an exhaust outlet, the exhaust outlet should be located at the intersection of the exhaust pipe.

8. The gutter and the cornice should be added to the additional layer, and when the asphalt waterproofing membrane is used, a layer of membrane should be added; when the polymer modified asphalt waterproofing membrane or synthetic polymer waterproofing membrane is adopted, the waterproof coating film reinforcement layer should be used. The additional layer at the junction of the gutter, the gutter and the roof should be empty, and the width of the empty shop should not be less than 200mm; the end of the gutter and the cornice membrane should be sealed and fixed.

9. When the daughter wall adopts cast-in-place reinforced concrete structure, the spacing of the expansion joint should not be greater than 12m. The top of the daughter wall and gable should drain inward with a slope of not less than 5%. When the daughter wall is a brick wall, the coil end can be directly pressed under the concrete pressure of the daughter wall, such as when the daughter wall is higher, a groove can be left on the brick wall, and the coil end should be pressed into the groove and fixed with a compression strip nail, and the infill sealing material is closed, and the height of the groove from the roof surface layer should not be less than 250mm. When the daughter wall is concrete, the end of the coil is fixed by galvanized steel plate press or stainless steel strip, the nail spacing is ≤ 900mm, and it is sealed tightly with sealing material.

10. The roof deformation seam should be pre-filled with non-combustible insulation materials, and the upper part should be filled with padding materials and covered with coils. The top of the contour deformation seam should be buckled reinforced concrete or metal cover, and the joints of the concrete cover should be sealed with sealing materials; the metal cover should be firmly paved, and the lap joints should be in the direction of flowing water, and anti-rust treatment should be done. The waterproof membrane cover and metal cover of the high-height span deformation seam on the high-span wall surface are fixed by metal compression strip nails and sealed with sealing material.

11. The buried height of the water drop mouth cup should be correct, the slope -10- degree within the 500mm range around the water drop mouth should not be less than 5%, and should be coated with waterproof paint first, the thickness of 2mm is appropriate, and the waterproof layer and additional layer should not be less than 50mm into the water drop cup. A 20 mm wide and 20 mm deep groove should be reserved at the contact between the water drop cup and the base layer to be embedded with neutral silicone weather-resistant sealant.

12. The reserved position of the back beam over the water hole should be correct, and its pipe diameter shall not be less than 75mm. The holes of the water holes should be covered with waterproof paint, and grooves should be left at the contact between the two ends of the buried pipe and the concrete, and sealed with neutral silicone weathering sealant.

13. The base of the roofing facility should be directly set on the roof structure, and the additional waterproof and flooding structure treatment should be done according to the requirements.

14. Within 500mm of the root of the pipe protruding from the roof, the mortar leveling layer should be smeared with a height of not less than 30mm arc, and a waterproof additional layer should be made around the root of the pipeline, and the width and height should not be less than 300mm. The height of the waterproof layer laid on the pipe should not be less than 250mm, and the end is tightened with a metal hoop and sealed with a sealing material.

15. The waterproof protective layer should be provided with compartmentalization seams. The compartment area of the cement mortar protective layer should not be greater than 1㎡, the compartment area of the plate material protective layer should not be greater than 100㎡, and the compartment area of the fine stone concrete protective layer should not be greater than 36㎡. The width of the compartment seam should be 20 ~ 30mm, the depth is the same as the thickness of the protective layer, the seam is embedded with asphalt horseshoe grease and other waterproof sealing materials, the flexibility and toughness of the sealing material should meet the requirements, and it should not flow at high temperature, and should not be brittle when low temperature. Between the rigid protective layer and the daughter wall and the gable wall, there should be a gap with a width of 30mm, the depth is the same as the thickness of the protective layer, and the gap inlaid waterproof sealing material is the same as the method of compartment seam.

16. Pipes, equipment or embedded parts protruding from the roof should be installed before the construction of the waterproof layer. After the roof waterproof layer is completed, no holes or heavy objects must be made on it. When roofing solar energy, fire protection and other facilities, equipment, pipelines are installed, effective protective measures should be taken to avoid damaging the waterproof layer.

17. After the completion of the roofing project, the construction unit shall organize the construction and supervision units to do water storage tests or water tests to check whether the roof drainage is smooth, whether there is water accumulation and leakage, and retain photos and video data for archiving. The flat roof should be tested for water storage, the water storage time is not less than 24 hours, the shallowest part of the water storage is not less than 20mm, and the deepest part should be lower than the water penetration height of the waterproof layer. For the slope roof, after rain or after 2 hours of continuous water, observe and check whether there is leakage, and should make a record. The flat roof should also be water-filled during pre-completion inspection (except for winter construction).

Fifth, floor heating ground leakage prevention and control measures

1. The construction unit shall prepare a special construction organization design or construction plan, and the construction shall be carried out only after approval by the construction and supervision unit.

2. The main materials, equipment components, accessories, insulation materials, etc. used in the radiant heating system must have quality certification documents, and their performance technical indicators, specifications and models should meet the requirements of the current national standards and design documents, and have the inspection report provided by the national authorized agency within the validity period. After entering the site, the construction, construction and supervision units should conduct joint acceptance, verify the consistency of the quality certification documents with the physical object, and conduct appearance quality inspection, and after meeting the requirements, witness sampling in accordance with regulations, and use it after passing the sampling inspection.

3. The original working surface of the insulation layer should be flat, dry and free of debris, and the root of the corner junction surface should be straight and free of ash accumulation. The laying of the insulation layer should be flat, and the seams between the insulation layers should be tight.

4. The ambient temperature of the heating pipe laying facility should not be lower than 5 °C. When constructing in an environment below 5 °C, heating measures should be taken on site.

5. The heating pipe cutting should use special tools, the incision should be flat, and the fracture surface should be vertical to the axis of the pipe.

6. The heating pipe should be installed to prevent the pipe from twisting. The bending radius of the plastic pipe should not be less than 8 times the outer diameter of the pipeline, the bending radius of the aluminum-plastic composite pipe should not be less than 5 times the outer diameter of the pipeline, and the bending radius of the copper pipe should not be less than 5 times the outer diameter of the pipeline (the copper pipe should use a special mechanical elbow). The heating pipe is fixed to the insulation layer with a plastic card or a steel wire card with a plastic sleeve on the surface, and the spacing of the fixed point should be 500~700mm, and the curved pipe section should be 200~300mm.

7. The heating pipe buried in the filling layer should not have a joint. When the pipe is damaged, leaked and other phenomena in the process of laying, it should be replaced in its entirety and must not be spliced and used.

8. In the water separator, water collector near and other heating pipe arrangement is more densely arranged, when the pipe spacing is less than 100mm, the heating pipe outside the flexible casing should be provided; the ring arrangement of the heating pipe should not cross the expansion joint of the filling layer, and when it must be crossed, the length of the expansion joint should be provided with a flexible sleeve of not less than 200mm.

9. When the concrete filler layer is constructed, the protection of the frame plate should be added to avoid damaging the heating pipe, and the concrete vibrating equipment is strictly prohibited from using plug-in mechanical vibrating equipment. In the construction of the filling layer, the pouring should be carried out with pressure, and the water pressure should not be lower than O.6MPa; During the maintenance of the filler layer, the water pressure should not be lower than O.4MPa.

10. During and after the maintenance of the filling layer and after the expiration of the period, protective measures should be taken, and no heavy load, high-temperature baking, direct placement of high-temperature objects and high-temperature equipment, etc., the area where the construction is completed shall not be used as an operation processing area or living area, and no culling, chiseling, cutting, drilling and nailing the filling layer shall be removed, chiseled, cut, drilled and nailed, and no objects shall be wedged into the filling layer.

11. The pressure test of the concrete-filled ground radiant heating indoor system should be carried out twice, before pouring the concrete fill layer and after the expiration of the maintenance period of the filler layer. The water pressure test pressure should be 1.5 times the working pressure and should not be less than 0.6MPa. Under the test pressure, the pressure is regulated for 1h, and the pressure drop should not be greater than 0.05MPa, and it is not leaky or leaky. When the water pressure test is carried out in winter, in the case of freezing, reliable antifreeze measures should be taken, and the water in the pipe should be blown clean and dried in time after the pressure test is completed to prevent the pipeline system from freezing and cracking.

12. During the pre-completion inspection, the ground radiant heating indoor system should maintain the working pressure when the weather permits.

Sixth, cast-in-place reinforced concrete floor crack prevention and control measures

1. The general contractor of construction shall formulate a special construction plan for the prevention and control of cracks in cast-in-place concrete floor slabs.

2. The supervision unit shall formulate the implementation rules for the supervision of the side station of the construction of the cast-in-place concrete floor slab, and clarify the key points of crack prevention and control monitoring.

3. When supplying ready-mixed concrete, the ready-mixed concrete production unit should provide the "Ready-mixed Concrete Product Specification" to the construction unit to clarify the precautions for the prevention and control of concrete crack construction: (1) the initial and final condensation time of the concrete; (2) the expected age of the concrete strength of more than 75%; (3) the construction load time of the concrete from the pouring to the lifting of the steel bar, formwork and other construction loads;(4) the concrete maintenance method and time suggestion; (5) other construction precautions that may cause cracks caused by the concrete's own characteristics.

4. The selection of the formwork and its bracket must be calculated, in addition to meeting the strength requirements, it must also have sufficient stiffness and stability to reliably withstand the self-weight of the poured concrete, the lateral pressure, the load generated during the construction process and the load generated during the construction of the superstructure. The distance between the side support pole and the wall shall not be greater than 300mm, the middle should not be greater than 800mm, and the bottom of the pole should be provided with a pad; the support system directly supported on the ground must take measures to fully consider the deformation that may occur after the ground load of the support system foundation. The number of turnover sets of the template system should not be less than 4 sets.

5. Strictly control the thickness of the cast-in-place plate and the thickness of the steel protection layer in the cast-in-place plate. Balconies, awnings and other cantilevered cast-in-place plates under the negative bending moment of the steel bar, should be set up with a spacing of not more than 300mm steel protection layer horse stool, in the pouring of concrete to ensure that the steel bar does not displace.

6. The conduit should be laid on the board and the middle of the lower two layers of steel bars, and the horizontal spacing should not be less than 50mm; it is strictly forbidden to stagger and stack the three layers and more of the line pipe, and if necessary, along the direction of the pipeline, a φ4@100 wide 600mm steel wire mesh piece is added as a reinforcement measure.

7. When the ready-mixed concrete enters the site, the construction and supervision unit must check the slump degree of the mold according to the inspection batch, and when there is segregation, the secondary mixing should be carried out, and the mixing time should be determined by the laboratory. It is strictly forbidden to add water to the concrete transported to the pouring site. The concrete slump of high-rise residential floor slabs and roof panels should not be greater than 180mm, and the concrete slump of other residential floor slabs and roof panels should be controlled at 120~150mm, and should meet the requirements of design slump.

8. Add fiber measures can be used to increase the tensile strength of concrete and control the cracks of concrete in cast-in-place floor slabs and roof panels. Concrete pouring should try to avoid the high temperature period of the day, and reasonably determine the pouring sequence and the retention of construction joints.

9. Secondary vibration should be carried out before the initial condensation of concrete, and secondary smearing should be carried out before final coagulation.

10. Strengthen the maintenance and insulation of cast-in-place concrete floor slabs, and control the structure and the external temperature gradient within the range of 25 °C. After the concrete is poured, it should be covered and watered within 12 hours, and the maintenance time shall not be less than 7 days; for concrete mixed with retarded admixture, it shall not be less than 14 days. In summer, the maintenance time should be appropriately extended to improve the ability to resist cracking. In winter, the heat preservation and demoulding time should be appropriately extended to prevent sudden temperature changes and excessive temperature differences from causing cracks.

11. The position of the rear pouring belt should be strictly in accordance with the design requirements and construction plan. The rear pouring belt should be located in the part where the structure is less affected by the force, and the width should not be less than 800mm. The post-pouring belt concrete pouring should be carried out after the age of the concrete on both sides is at least 60 d, the strength level should be one grade higher than the concrete on both sides, and the compensatory shrinkage concrete should be used for pouring, and its maintenance time is not less than 15 days.

12. Strictly control the time of people on the board and loading. Set up a bulletin board at the landing of the stairwell on the current floor to clarify the time of the upper person and the upper load. The release time of the person on the plate surface shall not be earlier than 18 h (April to November) and 24 h (December to March) after the final condensation of the concrete; the time for lifting the formwork, steel bars and other materials on the board surface shall not be earlier than 36 h (April to November) and 48 h (December to March) after the concrete final coagulation. The lifting material should be less hanging and light, and the rush-16-hit caused by the lifting load on the floor slab should be reduced. Materials shall not be stacked centrally, wooden cushion boards shall be laid at the stacking place, the position shall avoid the middle part of the floor slab, and the temporary load shall not exceed the load limit specified in the design document.

13. Strictly control the time of mold removal of floor slabs. After the maintenance test block of the floor concrete with the same conditions reaches the strength value specified in the specification, the support formwork can be removed.

14. Reasonably set the duration of the main structure. The floor construction speed of the main structure stage should be controlled in 6 to 7 days to ensure the maintenance time of the floor concrete.

15. Cracks found in the floor slab during the construction process should be treated according to the following procedures:

(1) The construction unit shall organize the design, construction, supervision and ready-mixed concrete production units to find out the distribution and width of the cracks in the floor slab.

(2) Comprehensive analysis of the nature of cracks and the causes of their occurrence.

(3) When the crack is found or the scratch is too large, the corresponding part of the damage state, concrete strength, diameter, spacing and location of the steel bar should be tested to meet the design requirements, and the original design unit or a qualified unit should be entrusted to issue a handling opinion according to the test results, and the corresponding qualified unit should be selected according to the processing opinion, and a record should be formed.

(4) After the crack treatment of the floor slab, special acceptance should be organized and a data archive should be formed.

Seventh, fill the wall wall crack prevention and control measures

1. Autoclaved (raised) bricks, concrete small hollow blocks, autoclaved aerated concrete blocks of wall materials can be maintained for at least 28 days before the wall masonry; blocks should be stored in a special protective shed, there are reliable moisture-proof, rain-proof measures; broken, lack of edges and corners and other blocks shall not be used.

2. Masonry mortar should be prepared mortar, masonry in stages, each masonry height should not exceed 1.5m, the daily masonry height should not be greater than 2.8m. -

3. At the vertical junction of the infill wall and the surrounding concrete structure, it is advisable to leave a wide gap of 15 to 20 mm. After the completion of the wall masonry, the secondary cauldron of dry hard cement mortar mixed with an expanding agent of not more than 5% of the cement weight is used, and the embedded is densely packed.

4. When the infill wall masonry is close to the bottom of the beam plate, a certain gap should be left, at least 14d intervals to be settled after the settlement is basically stable, and then squeeze it tightly. When using the top "rolling brick" to repair, the two ends and middle of the "rolling brick" should be repaired with prefabricated triangular concrete blocks, and the slope of the rolling brick should be controlled at about 60 degrees; when the fine stone concrete is used to fill, the bottom of the beam (plate) should be reserved for 30 to 50mm gaps, filled with dry hard C20 or more expanded fine stone concrete, and squeezed with anti-corrosion wood wedges (spacing is not more than 600mm).

5. When filling the wall with holes and slots, apply special tools to avoid hammering and chiseling. The depth of groove removal should ensure that the outer surface of the line pipe wall is not less than 15mm from the base layer of the wall surface, and is smeared with 1:3 cement mortar. The dense parts of the conduit should be filled with fine stone concrete.

6. Reinforced concrete girders should be added to the upper part of the temporary opening of the wall, and 2Ф6 knot ribs should be reserved on both sides of the wall, with a spacing of 500mm, and the connection should be wet and solid when repairing.

7. The vials on the reserved holes such as fire boxes, distribution boxes, water meter boxes, switch boxes, etc., should be reserved for holes and grooves in the position where their line pipes cross, and must not be chiseled afterwards.

8. The junction of different substrate materials, the groove part, the sides of the temporary opening, the back of the watch box, etc. should be nailed to hang the steel wire mesh. The lap width of the wire mesh with different substrates is not less than 100mm on each side. The mesh size should not be greater than 20mmх20mm, the diameter should not be less than 1.2mm, and the steel wire mesh should be made of post-hot-dip galvanized welded mesh after galvanizing. The wire mesh shall be fixed by steel nails or projectile nails and iron sheets, and the spacing shall not be greater than 300mm.

9. Wall plastering should be prepared mortar. After the bottom layer plastering is completed, the entire wall should be covered with alkali-resistant glass fiber mesh cloth before plastering layer ash-18-, and the mesh cloth should be accepted according to the concealment project.

10. Wall plastering should control the thickness of each layer of plastering. When the total thickness of plastering exceeds 35mm, anti-cracking measures such as adding steel wire mesh should be taken.

Eighth, the ground cracking prevention and control measures of the floor heating building

1. The ground concrete of the floor heating building should give priority to low-grade concrete with small slump, strictly control the amount of fly ash, and incorporate a certain amount of UEA micro-expanding agent.

2. In order to prevent the floor from cracking, a layer of anti-crack steel wire should be added to the surface of the floor heating pipeline. The steel wire mesh shall not be close to the coil, and the protective layer shall not be less than 20mm; the steel wire mesh must be disconnected at the boundary grid, the edges are neat and laid in place; when the local lap is used, the lap width should not be less than 200mm, and each point must be tied firmly.

3. During the concrete pouring process, the heating pipe and steel wire mesh shall not have the phenomenon of warping, so as not to affect the thickness of the protective layer on the heating pipe and the phenomenon of leakage of the net.

4. Floor concrete pouring is suitable for secondary molding, after the secondary plastering of concrete, immediately covered with plastic film and other materials, strengthen early maintenance, maintenance time is not less than 7 days.

5. The concrete filling layer should be equipped with expansion joints:

(1) When the ground area exceeds 30m2 or the side length exceeds 6m, the expansion joint should be set according to the spacing of not more than 6 meters; the junction of the ground and the vertical components such as the inner and outer walls and columns and the doorway, the narrow corridor and the ground intersection of the large room should be set up, and the width of the expansion joint should not be less than 8mm; the expansion joint should be made of high foam polyethylene foam plastic board, or the preset wooden slats should be removed after the completion of the construction of the filling layer, and the seams should be filled with elastic expansion paste.

(2) The expansion joint should be from the upper edge of the insulation layer to the upper edge of the filling layer.