On the construction quality control of concrete construction

[Abstract] are widely used in concrete construction, water conservancy, transportation and other projects of construction, the project plays an important role in the structure, its quality and the quality of the entire construction process is closely related to the concrete construction, often appear some common general quality issues, this paper analyzes the causes of these problems, and then give the appropriate control measures.

[Keyword] concrete, quality, control

An impact on the quality of coagulation factor
As we all know, to be able to control the construction quality of concrete, we must first understand the factors affecting the quality of the concrete itself to be able to find appropriate ways to improve the quality up, the following factors affecting the quality of several aspects of concrete to give elaborate.

1.1 The impact of raw materials
Construction of concrete raw materials for construction quality has a direct impact, good or bad quality of raw materials will directly determine the quality status of the building, so the good quality of raw materials is particularly important raw materials of concrete, mainly from the following aspects to grasp:
1.1.1 yellow sand for sand-clay for its volume and fineness modulus is the primary factor affecting its quality, whether the sand is too fine or too much clay content will increase the concrete shrinkage cracks, and from another side, if the sand in its high clay content, may affect its frost resistance, durability, impermeability, and the overall strength of the concrete. Therefore, the choice of gravel concrete, they should choose organic matter and clay content are to meet the specification in the sand.

1.1.2 stones. On the stone is mainly to control the value of its crushing, grading and the flakiness of the content, they are the main factors affecting the quality of stones, now according to some market research found that many building stones of values ​​are not graded or crushed to meet the requirements of construction quality, so the purchase of building materials gravel gravel grading to pay attention to their crushing values.

1.1.3 cement. Cement soundness and strength of will directly affect the quality of concrete, when the difference between soundness of cement, the expansion will result in concrete or cracks, and concrete strength will fluctuate up and down to follow the fluctuations in concrete .

Ratio of 1.2 with
Concrete is a series of raw materials are mixed together according to certain proportion of the complex, the quality of concrete, it's flat water, water-cement ratio and sand percentage constitutes a mix of three basic elements of influence, they are between the various properties of concrete has a very close association in the use of this principle to be followed: to meet the requirements of the workability of concrete, based on the coarse aggregate according to the specifications to determine the concrete unit of water consumption, and in the meet the durability and strength of the concrete foundation, concrete water-cement ratio is determined, in the aggregate amount of sand should be to fill the gaps between the stones even after a slight surplus of principles to determine.

1.3 Concrete pouring
Concrete pouring of the concrete impact on the quality of the main branch is located and vibrated from the template are two major implications when using plug-in vibrator concrete vibrator, when to do fast pull slowly pounding, the vibration time should controlled in a certain range.'s branch is located on the template control is necessary to stand firm, and the template will have to clean the surface dirt, joints between the template and the template to be tight.

1.4 Maintenance
After the concrete forming the conservation of the quality of concrete has a direct relationship between the concrete surface after the condensate is good, still in the further hydration of cement, concrete strength at this time is constantly increasing, so in dry weather, a timely manner for watering, let the concrete surface wet enough to prevent cracks.

2 concrete construction quality problems and cause analysis
2.1 Drain ribs
Reinforced concrete in some or all of the bare, exposed naked and exposed steel, which is a manifestation of the quality of concrete, it causes may be pouring in the design of components, design appropriate Debu too close to make steel, pouring concrete in the lack of adequate protective layer, making the steel mold can only close to live, another reason may be improper concrete mix based on the pound vibration inappropriate, artificially reinforced displacement, deformation resulting in a reinforced of leakage.

2.2 Ma and cellular surface
Another quality of the concrete performance of the local emergence of concrete mortar less crisp, more stones, gravel and stone as if the gap between the honeycomb of holes, and lack of local surface pulp, pits, and many small pits, the formation of rent rough surface but not exposed steel and so on. According to some research found that the causes of these phenomena are: (1 concrete in the mixing process is uneven or insufficient time, making the poor workability of concrete (2 of concrete between the various raw materials with the proportion of inappropriate , making the proportion of sand and gravel and other uneven sand and gravel less than more (3) more than two meters below the time expected, there is no time to even string string tube tube, allowing segregation between mortar and stone.

2.3 lack of concrete strength, poor homogeneity
In the course of discovery, the same batch of concrete strength is not expected strength or the strength of strong design, it produces may be due to the following aspects: (1 degree allowed concrete composition, and optionally in the operation random water, making higher than the gray (2 in the final setting of inadequate maintenance, coupled with the concrete problems of the production itself (3 cement raw materials stored too long or too humid storage locations, allowing cement viscosity condensate function is impaired, and in the amount of blending, the use of disproportionate. Links to free download http://www.hi138.com
2.4 holes and holes appear
In the final setting of concrete always such a phenomenon occur within the larger concrete structure of the gap, thus having holes of the case, it causes are: (1 mortar separation, accumulation of piles of stones, but a serious run pulp vibration is not timely for pound (2 steel embedded in some of the more intensive office or place under the concrete material was put to live but have not found or found but turned a blind eye, but no trace in the case of vibration to continue to upper pouring concrete.

3 ensure quality of construction of concrete measures
A good grasp of the conservation system 3.1 strict
In the concrete quality assurance, it is extremely important conservation areas, many of the problems in the concrete, according to research to analyze the reasons is not a single problem of raw materials, the ratio of technical and other improper influence or pounding vibration, and maintenance aspects of the operation improper construction quality of concrete is constantly increasing, the main cause of this problem is the construction to be completed more quickly, significantly reducing curing time, so that the concrete and cement hydration is not sufficient, according to the Experts test results show that its conservation is stronger than all wet 28d, full wet curing is 3d, air conservation of 28d. So, for those large volume of concrete pouring volume conservation programs should be designed from the beginning to the conservation of maintenance must be ending corresponding experts, both from a subjective or from technical maintenance personnel must have sufficient knowledge of conservation. from water conservation programs, personnel, cover, day and night and other aspects to consider, prioritize grasp the details, to strengthen the conservation period supervision. the conservation measures taken and on-site maintenance situation, and its track record, the timely detection of problems in order to ensure the conservation effectiveness.

3.2 pairs of quality control of raw materials
Composed of various raw materials for concrete, make a good quality, more specifically, in the purchase of various materials to choose a regular factory, and there must be other products like cement, certification, and no agglomeration is fresh, and in placement process, a variety of materials to choose, depending on the material properties of different physical environments depot, for example, the cement should not be stored in moisture.

3.3 good grasp of the concrete mix
Concrete mix in strictly on the basis of good quality raw materials must be strictly design, concrete mix should be controlled strictly in accordance with the proportion to be stirred frequently Hing check the accuracy of measurement in concrete, mixing is uniform of concrete mix if the project in its own capacity is inadequate to determine, if necessary, to seek expert to solve them, not blindly self-creation.

3.4 Reinforced concrete grasp
When casting concrete, reinforced protective layer to ensure the correct thickness and location, on this basis to strengthen the inspection and investigation, steel-intensive, should be appropriate to reduce the size of stones, concrete mix in order to ensure accurate and good workability, The height of more than 2m of water when the application string tube, or chute for the next feed controls to prevent segregation of reinforced concrete vibrator impact is strictly prohibited.

4 Conclusion:
The building of concrete construction quality control, in control of the main factors affecting the concrete and in reality, mainly in the quality of the concrete behind, and these issues cause analysis, to capture the overall macroeconomic solve some of these issues measures, then the building of concrete construction quality control easier to grasp.

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