What are the disadvantages of a concrete wall with a very smooth surface?

With the development of industrial and civil construction, the use of reinforced concrete is also growing rapidly, but some problems of reinforced concrete in construction should not be ignored. This paper starts with the problems of reinforced concrete in construction and analyzes the causes in detail, and finally also puts forward the detailed strategies to change these problems.

In recent years in the construction of industrial and civil building projects, reinforced concrete works, in the construction of construction to widely used, that is, the amount of reinforced concrete surface plastering project has also increased dramatically, so we are in the construction of decorative engineering, often found in the concrete surface plastering project, there are varying degrees of cracks, cracks, drums, and even peeling phenomena, become the surface of concrete plastering It has become a common quality problem in the concrete surface plastering project. In order to ensure the quality of the project, we have listed the reinforced concrete surface plastering project as a key inspection project, and achieved good results by strict control in the construction. Now will be in the construction of the project are briefed as follows;

A project construction;

Reinforced concrete surface plastering, generally using cement mortar, cement mixed mortar, cement mixed mortar bottoming lime mortar plastering, as well as the use of cement perlite mortar plastering and so on.

The smoothness of reinforced concrete surface, generally for the use of different templates and different, using steel moldboard or composite multi-layer board, and composite multi-layer bamboo template, construction of reinforced concrete load-bearing structure, the surface of the component is relatively smooth, the use of ordinary wood templates, but also according to the template surface planing or end of the planing to determine. Therefore, the surface of the concrete is smooth and relatively, some rough and relatively rough.

Reinforced concrete surface plastering engineering construction quality problems, generally more cement mortar than other mortar plaster; in the process of project construction cast-in-place concrete load-bearing structures, components, concrete shear, reinforced concrete silo structure, frame structure, concrete surface plaster surface, decorative works, prone to cracks, cracks, cracks, hollowing and other problems. Some of them occur during the construction of the project, some of the cycle is longer to occur after a longer period of time, and even after completion and after using a period of time to occur.

Two, cause analysis;

(a), drum;

1, the concrete surface is smooth, due to the use of steel mold casting concrete, demolding the concrete surface is relatively smooth, thus weakening the bond strength of the combined layer and plaster layer is prone to drumming.

2, the concrete surface adhering to the isolation agent end clean up, because the surface of the template before the concrete pouring generally shabu a layer of isolation agent, generally using oil or water powder material, but in the demolding will be bonded to the concrete surface to form a layer of isolation film gc5.com, such as can not be cleaned up will result in the concrete and the plaster layer falling off.

3, plastering using materials that do not comply with the provisions of the inappropriate, there are in the concrete surface directly coated with lime mortar. Due to the different nature of cement and lime materials, bonding strength is very poor, thus causing the plaster layer fall.

4, the grass-roots level surface is not flat, vertical not vertical, plaster layer is too thick, plaster layer mortar if too thick, due to shrinkage and deformation of a larger amount, affecting the ability of mortar bonding strength. In addition, due to the operation of the operation in a hurry, plastering operation once live its mortar bonding force is less than the contraction stress, etc., the plaster layer is prone to cavitation.

(2), cracks

1, mortar water-cement ratio is too large, plastering mortar, such as water consumption is too much water too much water evaporation of the formation of pore space is large. That will also affect the strength of the mortar, especially cement mortar is more obvious at the same time also weakened the mortar cohesion and strength, thus reducing the resistance to internal and external damage to the strength of the ability, when the mortar water-cement ratio is too large (consistency of the corresponding small) will produce another problem, that is, the plaster layer is easy to plaster the surface of the grass-roots level down, resulting in transverse cracks in the plaster layer.

2, the plaster layer is not compact, due to the uneven surface of the grass-roots level caused by the uneven thickness of the plaster layer is not uniform, uneven plastering, not compact, and therefore produce shrinkage ratio is not consistent and produce cracks.

3, due to the hollow drum and cracks gc5.com, plaster layer where there is a hollow drum parts after the impact of external forces, easy to crack.

4, raw material selection with improper, such as the selection of poor cement stability, sand selection does not comply with the provisions of the specification, sand crushed diameter too fine, etc., easy to produce cracks in the plaster layer.

5, belonging to the design reasons, such as foundation, foundation, uneven settlement, structural deformation, structure, components, deflection, displacement, etc. will lead to wall or ceiling cracks in the plaster layer.

Third, take technical measures;

Plastering works before construction of grass-roots or substrate, must be cleaned, cleaned up must be in line with the provisions of the construction acceptance specification and the provisions of db-23. Construction drawings should be reviewed before construction, review of architectural construction drawings and structural construction drawings, geometric dimensions, elevation, detail dimensions, and nodes and so on. As far as possible to consider to meet the construction requirements, and decorative engineering construction and construction, engineering quality requirements and specifications, should also meet the following requirements.

(I), concrete surface cleanup and grass-roots level wetting;

1, grass-roots level cleanup;

Plastering before the concrete surface must be cleaned up will be bonded dust, residual mortar, etc. clean up, on the surface of the concrete in the pouring of isolating agent, etc. should be according to the different kinds of different measures taken to clean up, scrub. Such as the use of waste engine oil as isolating agent, should be washed with kerosene water solution, and then must be rinsed with water.

2, wet grass-roots level;

Plastering before the grass-roots level wetting is a very important, construction operation process must be done. According to the construction experience generally take the night watering wet grass-roots level (i.e., plastering project construction the day before watering wet grass-roots level). Grass-roots watering and wetting generally to make the water penetrate into the concrete surface 2-3 mm appropriate, to be slightly dry after the concrete surface in the plastering, the purpose is to prevent early dehydration of plastering mortar, and so that the plastering mortar to the grass-roots level of the surface with a certain degree of stress absorption, even if the plastering mortar is quickly bonded and stabilized, so that plastering layer and the concrete surface bonded firmly.

(2), concrete surface and grass-roots level of several treatment methods;

1, chiseling;

generally used for smooth concrete surfaces, concrete demolding in the concrete structure, components of the strength of the lower, can be chiseling treatment, so that need to be plastered concrete surface chiseled into a rough surface is appropriate. In order to increase the bond between the concrete surface and plaster layer, in the operation of the treatment should pay attention to the depth of chiseling and smashing suitable for uniformity, in general, this method is often used in the construction of the project.

2, scraping or sprinkling slurry; (i.e., paste bone slurry)

Pre-plastering before the concrete surface gc5.com with cement paste, that is, cement paste water-cement ratio of 0.37-0.47 is appropriate, a thin layer of scraping the thickness of 1-2 millimeters is appropriate to wait until the cement paste is slightly dry to carry out the operation of plastering. Or use the cement paste to the concrete surface sprinkle, throw, make the concrete surface rough, to be dry after the cement paste piggyback in the plastering operation.

3, combined layer method;

In the plastering mortar mixed with a certain measure of latex water solution or polyvinyl alcohol formaldehyde gel 107 glue solution to enhance the adhesion with the grass-roots level. Smear thickness is generally 2-3 millimeters appropriate. Such as a large area of concrete surface plastering, or concrete slab project, or large template project, the project uses this method more, if the concrete grass-roots level surface is relatively flat, can also be used once the smoothing and calendaring A work.

3, mechanical slurry bottoming;

In the concrete surface to be plastered first sprayed 2-3 mm thick primer gray, because the mechanical slurry has a certain pressure, can increase the bond between the concrete and plastering mortar, and then in the middle layer and the surface layer of plastering.

(3), the choice of materials and basic requirements;

1, the use of good stability of the cement, the construction of coarse sand or sand should not be used in fine sand.

2, the water-cement ratio should be in accordance with the specification, the consistency of the mortar is prepared according to the requirements of grading to ensure the strength of the mortar.

3, the consistency of plaster mortar, easy, water retention, must comply with the construction acceptance specification.

4, in the construction process should be strictly controlled, the thickness of the plaster layer.