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dop设计(ID:dopdesign)原创
Author丨DOP Design
Wall body armor
The importance and necessity of wall plastering in the whole construction project is self-evident, it is no exaggeration to say that it is the "body armor" of all building walls, which can enhance the moisture-proof, thermal insulation, thermal insulation performance of the building, and play a protective role in the building;
However, due to various reasons, the "body armor" on our walls eventually cracks, hollows, and even falls off (turn your head to look at the walls around you, be careful, and look for cracks or hollows on the walls)
Why do wall "body armor" cracks and hollows?
Below, we put aside the force majeure factors (earthquake, tsunami, building settlement, structural damage, etc.), and comprehensively analyze the causes and avoidance methods of wall plaster cracking from the three controllable dimensions of materials, construction, and external factors.
1. There is a problem with the material itself
2. Poor control of the construction process
3. External factors are unpredictable
01. There is a problem with the material itself
1. Lack of adhesion of base materials:
(PS: The base materials mentioned below are common wall block materials such as concrete walls, aerated blocks, cement slats, hollow bricks, gypsum blocks, etc.) )
The wall base material is too dry and damp.
Before construction, the wall surface is not swept with water, which causes the base material to absorb the moisture of the cement mortar plastering layer, so that the plastering layer shrinks too much, causing the mortar layer to crack;
The base material of the wall is too smooth,
The surface of the material is too smooth and lacks adhesion, causing the plastering layer to slip and fall.
The instability and inhomogeneity of the block base (aerated block, gypsum block, cement slat, hollow brick and other common masonry walls) lead to the quality of the wall base, which causes cracking and hollowing of the plastering layer.
The instability of the block refers to: low strength, large shrinkage, high water absorption, soft surface, easy to fall off, weak adhesion and other shortcomings.
The inhomogeneity of the block refers to: the shape of the block itself has a large deviation, the density of each piece is inconsistent, local damage, cracks, resulting in inconsistent width of ash joints during masonry.
To sum up, the reasons for the cracking of the wall caused by the wall base material can be summarized as follows: the lack of adhesion of the masonry base itself, and the unevenness and instability of the block itself lead to the mortar layer can not be strongly bonded with the wall. After a certain period of time, the mortar layer slides and shrinks, causing cracking and hollowing of the wall.
2. The water retention of cement mortar is too poor:
The raw materials of cement mortar are unqualified:
The cement is not up to standard, the sand is too fine, and the mud content is high. As a result, the water retention of the finished mortar after the ratio is poor, and the moisture is easy to be absorbed by the base wall, which in turn causes the cement mortar to harden and shrink in advance, and the modeling plastering layer cracks.
The cement mortar production process is not rigorous:
In the process of making cement mortar, it is not screened or contaminated, resulting in the presence of coarse bones or foreign objects (such as glass slag, wood slag, etc.) in the cement mortar.
Or in the process of stirring, the mixing time of the mortar is insufficient, and the stirring is not uniform, resulting in problems with the stability of the plastering material itself. For example, the plain cement layer appears in the plastering process, which reduces the strength of the plastering layer, and increases the shrinkage and water absorption of the plastering layer, so it leads to the falling off and cracking of the plastering layer.
To sum up, the improper operation in the process of raw material selection, production and mixing of mortar is a hidden factor that causes cracking and hollowing of the plastering layer in the later plastering process.
Why does the wall crack, and why does the latex paint fall off?
Why is the stone hollow, and why is the wooden floor cracked and warped?
What should I do if the ceiling is wrong? What should I do if the height of the railing is not right?
……
For more knowledge about the common problems of interior design and construction quality, material application, construction technology, etc., you can learn the "DOP Design Practical Guide"
02. Poor control of the construction process
1. The technical disclosure is not in place
Failure to construct in layers according to the national standard or the time interval between two layers of plastering is too short.
The plastering layer is formed at one time during the construction process, resulting in the plastering layer being too thick and shrinking greatly, resulting in the cracking of the plastering layer itself, causing hollowing. This type of cause is the cause of wall hollowing in the vast majority of construction sites, because of the emphasis on prevention.
The bottom ash was not marked according to the specification.
During the construction process, there is no marking treatment according to the national standard specification, resulting in the weak adhesion of the bottom mortar, which is easy to fall off and crack. This type of reason is the main reason for the weak adhesion of the plastering layer itself.
The junction of different materials on the wall is not treated with a hanging net.
Due to the different hardness and shrinkage of the material at the interface of the concrete wall and the wall of other materials, if the net is not hung during the construction process, it will lead to the difference between the plastering layer and the base wall after contact, and the effect of natural causes such as thermal expansion and cold contraction will cause cracking and hollowing. This is also a problem that is easy to be ignored on many construction sites, and it is the hardest hit area of wall cracking, so it must be paid great attention to.
The ultra-thick plastering place has not been treated with a secondary net.
When the flatness of the base layer is seriously insufficient (mainly the deviation of the civil wall), and the wall finishing material has extremely high requirements for the flatness of the foundation wall (latex paint, wallpaper, etc.), it involves the construction of ultra-thick plaster, and the so-called ultra-thick plastering is "the area with a plastering thickness of more than 35mm".
If the thickness of the plaster is too thick, it needs to be treated with a net to increase the adhesion of the plastering layer and reduce the shrinkage of the mortar layer.
After the plastering was completed, the sprinkling and maintenance were not carried out on time.
After the plastering is completed, it will gradually solidify and harden, a process that is mainly achieved by the hydration of cement, which must be completed under the appropriate temperature and humidity conditions. This means that if the cement is not cured without sprinkling after completion, the cement curing is not guaranteed, and due to the lack of water, the plastering layer will dry out and crack.
2. There are hidden dangers in the operation process:
Before plastering, the base wall was not thoroughly cleaned.
There are floating dust, particles, oil stains, pollutants and other residues on the wall that have not been cleaned up. As a result, the plastering layer is not firmly bonded, so that the adhesion of the wall base layer itself decreases, and eventually leads to cracking and hollowing of the wall.
Before plastering, the base layer of the wall was not repaired.
In the actual plastering process, the masonry wall plaster joints on the construction site are often not full and dense. If it is not repaired, start the plastering work immediately, the plastering surface will definitely be due to the adhesion of the wall base layer is not enough, and the penetration of the ash joint is not full, thus causing hollowing.
In the plastering process, the mortar layer is not compacted, and the density of the mortar layer is not enough.
Due to the improper proportioning, the plastering layer itself has low density and strength, and the plastering layer is not compacted in the construction process, and the plastering layer shrinks significantly after completion, which leads to the cracking of the plastering layer and produces hollowing.
When the net is hung on the wall, the grid is not firmly posted and not nailed.
At the junction of the base wall of different materials, the hanging net is not installed firmly, and the steel mesh will rebound due to the force in the later plastering construction, resulting in the cracking of the wall.
Door and window holes, equipment openings and other reserved holes and wire box parts around the perimeter are not edge-closed.
After plastering the bottom ash, there is no edge closing and compaction treatment for key parts such as reserved holes, and then when other types of work are carried out later, due to the vibration and bump generated during construction, as well as the improper contact between the finished equipment and the hole, it is easy to cause the surrounding plastering layer to be damaged, and over time it leads to the cracking and hollowing of the plastering layer.
If you think about the cracking and bulging of the distribution box, door and window frames of your own home, you can understand it as the consequence of compaction and edge closing.
03. External factors are unpredictable
1. The protection of the finished product is not timely
2. Brutal construction
The construction site is a mess and dusty;
The parts that are easy to bump are not protected by the finished product;
The junction with the door and window frame is not densely impacted as required;
In the work of transporting materials, dismantling the scaffolding, etc., after accidentally touching and scratching the plastering layer, it is repaired;
3. Chaotic construction
When multiple types of work are operated at the same time, they are not coordinated, resulting in errors in the construction process and mutual interference, resulting in the completion of the plastering layer of the wall being shaken, impacted, fractured and cracked by the surrounding construction operations.
4. The construction environment is difficult to meet
5. The construction time cannot be satisfied
Now many engineering sites, due to various reasons, the normal construction time can not be satisfied, resulting in the situation of rushing to work; and because the plastering project is the front line in the decoration project and takes a long time, so the construction personnel can only compress the construction time of plastering with various measures. Finally cause the interval time between plastering plastering ash and plastering plastering is too short, and the sprinkling curing time can not be guaranteed, resulting in the plastering layer is not dry to carry out the face ash construction, and the face ash is not dry to carry out the finishing construction;
6. Construction is carried out in extreme environments
The national standard stipulates that when the ambient temperature is lower than 5 °C, all wet work construction is prohibited, that is, tiling, plastering, putty and other projects with moisture participation are not allowed to be constructed.
Brief summary.
The reasons for the cracking of the wall plastering surface analyzed above are simply summarized, and it is enough to remember the following three points:
1. The performance of the material itself is not good
As a result, the adhesion of the wall base is insufficient, and the cement mortar has poor water retention and is easy to shrink.
2. Poor control of the construction process
As a result, the technical disclosure is not in accordance with standard practices, and the supervision in the construction process is not effective, resulting in low-level errors.
3. It is difficult to prevent external factors
Factors outside the construction process cause damage to the wall plastering layer.
The above is a highly generalized three aspects, which can basically explain 90% of the reasons for wall cracking in the interior decoration;
Why does the wall crack, and why does the latex paint fall off?
Why is the stone hollow, and why is the wooden floor cracked and warped?
What should I do if the ceiling is wrong? What should I do if the height of the railing is not right?
What should I pay attention to in interior design?
What is the difference between grout, beauty sewing agent, porcelain sewing agent, and glass glue?
……
For more knowledge about common problems in interior design and construction quality, material application, construction technology, drawing deepening, etc., you can learn the "DOP Design Practical Guide"
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