What are the key points of prevention and control of quality accidents in reinforced concrete projec

First of all, it is necessary to prepare the prevention and control plan, from the man, machine, material, method, environment five control, focusing on the balcony and other negative moment reinforcement of the protective layer of the protective layer, such as the addition of steel stools, the bottom plate reinforcement should be added concrete cushion block, to prevent the steel bar from rusting, the control of different marks of concrete parts of the pouring, and another is the control of concrete cracks, such as the control of the construction progress, the preparation of 4 layers of templates, the weather is cold plus antifreeze and early strength agent, strictly control the concrete floor health time, concrete strength can not reach 5mpa, prohibit the master to put the line, when the next layer is constructed, To prevent dumping when hoisting, the material should not be stacked centrally, it should be placed in a small room, the upper and lower support frame pipes should be in the same vertical line, and it is recommended to cover it with plastic cloth after beating the concrete.

Prior prevention and control mainly in: the test of steel bars and concrete raw materials to ensure that the raw materials can meet the design and specification requirements; The control in the construction is mainly in: the specification and quantity of the steel bar, the length of the weld and the welding quality, the lap length, the anchorage length, the protective layer, etc., the formwork should ensure that the formwork has sufficient rigidity and stability, and the concrete quality prevention and control should pay attention to the concrete mix ratio, slump, whether segregation or water leakage, warehousing mode, warehousing temperature, vibration mode and light collection methods; After-the-fact control is mainly in:

Concrete maintenance method, time, temperature, etc., mold removal time, mold removal sequence and method, defect repair, finished product protection, etc.

In fact, for such problems, it is already very common. If you want to find information, I recommend that you collect it in the library, but my personal opinion is that these things are all about how to manage all aspects of the construction site well, right? In the whole management system, the management system plays an auxiliary role

More important is the improvement of site management methods.

A few days ago, China Construction 3rd Bureau and Metropark Technology reached a cooperation agreement to jointly create a dynamic supervision and management model. Handheld 3G monitoring is the core support system. Create a remote real-time management and control site management mode.

It is said that managing ten construction sites a day is no longer a hassle. At home, on a business trip, in the office. You don't need to go to the construction site to view the scene in real time.

To be honest, I really admire this designer who really solves a lot of problems for managers. You can find out.

Rebar; 1. Location.

2. Model. 3. Quantity.

4. Anchorage length.

5. Lap length.

6. a protective layer.

Concrete. 1. Slump on the spot.

2. Whether the vibration is uniform.

3. The most important thing is maintenance.

1. The classification of engineering quality accidents can generally be divided into several types There are many classification methods for construction engineering quality accidents: they can be divided according to the severity of the losses caused; It can also be divided according to the cause of its occurrence; It can also be distinguished according to the consequences caused by it or the responsibility for the accident. 1. Classification according to the degree of loss caused by the accident (1) A particularly serious accident refers to an accident that causes more than 30 deaths, or more than 100 serious injuries, or direct economic losses of more than 100 million yuan; (2) Major accidents refer to accidents that cause the death of between 10 and 30 people, or the serious injury of 50 to 100 people, or the direct economic loss of between 50 million and 100 million yuan; (3) Relatively large accidents refer to accidents that cause the death of 3 to 10 people, or the serious injury of 10 to 50 people, or the direct economic loss of between 10 million and 50 million yuan; (4) General accidents refer to accidents that cause the death of less than 3 people, or the serious injury of less than 10 people, or the direct economic loss of between 1 million and 10 million yuan.

The above includes this number, and the following does not include this number. 2. Classification according to accident responsibility (1) Guidance responsibility accident refers to the quality accident caused by engineering guidance or leadership error. (2) Operation liability accident refers to the quality accident caused by the operator's failure to implement the operation in accordance with the regulations or standards during the construction process.

3) Natural disaster accidents refer to quality accidents caused by force majeure such as sudden and serious natural disasters. 3.Classification according to the causes of quality accidents: (1) Accidents caused by technical reasons refer to quality accidents caused by technical errors in design and construction in the implementation of engineering projects.

2) Accidents caused by management reasons refer to quality accidents caused by imperfections or mistakes in management. (3) Accidents caused by social and economic reasons refer to quality accidents caused by economic factors and social malpractices and unhealthy practices that lead to wrong behaviors in construction. 2. Qualitative engineering quality accident 1, unqualified quality According to the provisions of China's GB T19000-2000 quality management system standard, where the engineering product does not meet the requirements of a certain provision, it is called unqualified quality; Failure to meet a requirement for intended use or a reasonably expected requirement is called a quality defect.

2. Quality problems: All those who do not meet the quality requirements and the quality of the project must be repaired, reinforced or scrapped, which causes direct economic losses of less than 5,000 yuan called quality problems. 3. Quality accidents: If the quality of the project is unqualified, it must be repaired, reinforced or scrapped, resulting in direct economic losses and losses of more than 5,000 yuan to become quality accidents. Article 137 of the Criminal Law: Where a construction unit, design unit, construction unit, or project supervision unit violates the provisions of the State and lowers the quality standards of the project, causing a major safety accident, the person directly responsible shall be sentenced to fixed-term imprisonment of not more than five years or short-term detention and shall also be fined;

Are you asking about quality accidents, or are they common quality problems?

Quality accidents are serious consequences and have a relatively large impact, such as formwork expansion or even collapse when pouring concrete, collapse of the support system, large holes in the concrete, and so on.

The common quality problems belong to the defects in construction, such as honeycomb and hemp surface on the surface of concrete, surface cracks that occur due to untimely maintenance, and shortening due to the lack of construction measures in winter.

In terms of prevention and control, formwork problems: the support system of concrete in important parts must be calculated, and the quality of formwork construction must be ensured, and reliable reinforcement must be ensured. Concrete pouring problems:

Full vibration, layered vibration, etc. Maintenance problems: timely maintenance, winter construction should have thermal insulation measures.

Honeycomb, hemp surface, strength can not meet the requirements.

Common quality problems in steel reinforcement engineering.

1. Raw materials:

1) The material inspection and storage do not meet the requirements.

2) Corrosion and pollution of steel bars.

Second, steel processing:

1. The specification is wrong;

2. The cutting length is not enough;

3. The stirrup size is wrong, the hook degree is wrong, and the length of the straight hook section is not enough;

4. The length of the hook does not meet the anchorage requirements;

5. The thread length of the sleeve connection is not enough;

6. The height of the stool is not enough;

7. Lofting the relationship between complex nodes without comprehensive spatial intersection;

8. The size and angle are poor, not straight and smooth, the bending point is not accurate, and the hook is short;

9. Different key grade steel bars and imported steel bars do not pay attention to the requirements of different bending forming radius;

10. The deformation has not been corrected during transportation and stacking.

Third, the common problem of steel binding and installation.

1. The deviation and spacing of the main reinforcement are not standardized;

2. The thickness of the protective layer of the main reinforcement is not enough. or the protective layer is too thick;

3. The lap position of the main reinforcement is wrong, the lap length is not enough, and the lap rate in the lap section exceeds the standard;

4. The welding is not standardized, and the lap welding length is not enough;

5. The specifications and models of the main reinforcement are incorrect, or small or the strength level is not enough;

6. The length of the infill area of the beam and column is insufficient; Blind stool.

7. The anchorage length of the cantilever reinforcement is not enough, and the direction of the cantilever reinforcement is wrong;

8. The place where the bending steel bar is added is not added, and the additional encryption hoop needs to be added on the side of the beam;

9. The beam waist bar is not placed, and the anchorage length of the beam torsion waist bar is wrong;

10. The column stirrups at the beam-column node are not placed;

11. The horizontal reinforcement of the shear wall is not placed at the intersection of the shear wall and the structural beam or the dark beam;

12. The spacing of multiple ribs is incorrect;

13. The negative reinforcement of the plate is not fully tied and formed into a figure-eight buckle;

14. For intersecting beams and columns with the same cross-sectional size, the main reinforcement of the beam is not bent into the column, resulting in the effective cross-sectional size of the beam becoming smaller;

15. The column reinforcement is not bent when entering the foundation such as the cushion cap, and the column reinforcement in the foundation is not placed stirrups;

16. The stirrups at the lap joint of the beam-column reinforcement are not encrypted;

17. The anchorage of the steel bar does not meet the requirements of the specification:

18. The main reinforcement is not tied in place (the main reinforcement at the four corners is not attached to the stirrup corner, and the middle main reinforcement is not attached to the stirrups);

19. The position of the main reinforcement is reversed (reversed under tension and compression, especially the cantilever beam and plate);

20. The stirrups are not set, and the main reinforcement runs seriously;

21. The rebar binding flower buckles, missing buckles, and loose buckles do not meet the requirements of the specification;

22. The stirrup spacing is uneven, the binding is not firm, and the main reinforcement is not attached;

23. The hook of the main reinforcement of the column and the hook of the main reinforcement of the plate are facing the wrong direction;

24. The steel bar joint is not badly opened;

25. The thickness of the protective layer of the steel bar does not meet the requirements;

26. The steel bars with welding requirements have not been welded test;

27. The welder does not have a special operation personnel post certificate, or the welder does not meet the welding conditions;

28. Failure to intercept test specimens at the site of the polishing brigade in accordance with the specifications.

29. Welding rod and flux do not meet the requirements

30. The welding quality does not meet the requirements;

31. The welded joint does not meet the requirements;

32. The threaded joint does not meet the requirements.

Cement, sand, superplasticizer and other raw materials after the inspection of the following supplements:

1. Strict inspection of on-site mix ratio.

2. Control the slump of concrete.

3. The construction in the rainy season and winter is done strictly according to the special plan.

4. Supervise its vibrating in place.

5. Lay a special walkway when dusting to reduce the damage of steel bars.

6. Supervise its timely maintenance.

The template can only be dismantled after the 7th age is reached.

I'll give you a brief outline:

Beforehand: construction organization, construction plan, quality management system, team disclosure, raw material testing, mechanical equipment preparation, emergency plan.

During the event: construction side station, perception inspection, process acceptance, raw material sampling inspection: perception evaluation, concrete strength test, structural testing, finished product protection.

Quality assurance measures for concrete works.

1. Commercial concrete is divided into different situations and different parts to make technical disclosures to commercial concrete manufacturers.

2. Concrete pouring: the structure is poured first column and then beam plate. The continuous pouring of the beam and plate is completed at one time, and the intermittent time for eating in the middle is not more than 40 minutes. When pouring the wall columns, the layers (within 50cm) vibrate and compact.

3. Concrete construction joints: floor construction joints, which are left in the parts of the structure that are less sheared. The following provisions should be observed when continuing to pour and pound the construction joints:

1) The compressive strength of the poured concrete should be greater than.

2) On the hardened concrete surface, the cement film and loose stones or weak concrete layers should be removed, and fully moistened and rinsed without water accumulation.

3) Before pouring, the construction joints should be covered with cement slurry or a layer of cement mortar with the same composition as the concrete for grouting.

4. The concrete should be carefully tamped so that the new and old concrete are tightly combined.

5. When the mud content of sand and stone exceeds the specified level, it must be washed.

6. The mix ratio of concrete composition materials should be used according to the data provided by the laboratory. When the material changes, the test mix ratio should be done in time: when the water content of sand and stone changes, it should be adjusted in time according to the actual situation.

All kinds of materials should be weighed accurately, and should not be converted by volume ratio. The measurement error is strictly controlled within the allowable range.

7. In order to prevent the change of slump and the loss of cement slurry, the transportation materials must be tight and do not leak water and slurry. And in use, the concrete residue hard block is often removed.

8. Before pouring concrete, the debris in the formwork must be removed, and the surface of the steel mold must be put on the demoulding oil before each turnover before using the formwork. The vibrating tamping concrete is used, and the vibration time of each point is appropriate to vibrate the concrete to the surface to show floating slurry and no longer settle. The upper layer of concrete is inserted into the vibrator before the initial setting of the lower layer, and direct contact with the steel bar should be avoided.

9. Concrete curing: In order to ensure the quality of concrete, we must do a good job in curing, when the concrete is finally set, before hardening, start to carry out sprinkling curing, pay attention to the water flow can not directly pour the concrete surface, should make the water flow spray in the form of fog. When the concrete strength is reached, lay a layer of straw bales, and regularly sprinkle water on the straw bales to keep the concrete surface of the floor slab wet.

Before the concrete is strong, people cannot trample on the concrete. Watering and maintenance should not be less than 14 days in summer and not less than 7 days in winter. When the roof is removed, the concrete strength must reach 75% of the design number, and attention should be paid not to damage the concrete surface when removing the formwork.

10. In the process of pouring concrete, the concrete test block must be carefully done according to the requirements of the specification and according to each team and quantity. Concrete test blocks must be randomly sampled on site and cured according to standards.