In building engineering, interlayer cracking is a common structural disease, which widely exists in concrete structures, floors, walls and other parts. It not only affects the beauty and function of the building, but also may pose a threat to the overall structural safety. Therefore, it is of great significance to identify and deal with interlayer cracks in time and effectively for ensuring the durability and safety of buildings.

First, the cause analysis of interlayer cracking

Interlayer cracking usually refers to the phenomenon of cracks or separation between upper and lower structural layers, which is common between floor slab and leveling layer, concrete structure and plastering layer. The main reasons include:

1. Material shrinkage difference: Different materials have different shrinkage rates during hardening, which easily leads to stress concentration between layers, thus causing cracking.
2. Improper construction: If the grass-roots treatment is not clean, the adhesive is unevenly applied, and the construction temperature is improperly controlled, the bonding strength between layers will be affected.
3. Structural deformation: factors such as foundation settlement, temperature difference change and uneven load may cause local deformation of the structure, which may lead to interlayer separation.
4. Design defects: If temperature stress is not considered and expansion joints are not set, the risk of cracking will also increase.

Second, the harm of interlayer cracking

Interlayer cracking not only affects the appearance quality of buildings, but also brings a series of potential hazards:

-affecting waterproof performance and causing leakage;
-reducing the integrity and bearing capacity of the structure;
-Accelerating material aging and shortening service life;
-In extreme cases such as earthquakes, it may cause serious security risks.

Third, the treatment method of interlayer cracking

The principle of "finding out the cause, comprehensive treatment and prevention first" should be followed in dealing with interlayer cracks, and the specific measures include:

1. Fracture evaluation and classification treatment
Check the cracks in detail to determine their properties (structural/non-structural) and width. For micro-cracks with a width less than 0.2mm, surface sealing method can be used to deal with them; For wide or developing cracks, grouting method is needed to reinforce them.

2. Strengthen interlayer bonding
In the process of construction, we should ensure that the base is clean and moist, choose bonding materials with excellent performance, and strictly control the construction technology. For the cracked parts, the loose layer should be removed and the combined layer should be laid again.

3. Structural reinforcement and repair
For structural interlayer cracks, carbon fiber cloth wrapping, steel reinforcement, pressure grouting and other ways can be adopted to strengthen and repair, so as to restore the bearing capacity of the structure.

4. Set expansion joints and control joints.
Expansion joints, settlement joints and control joints should be set up reasonably in the design and construction stages to release temperature stress and structural deformation stress and prevent cracks from spreading further.

5. Strengthen daily maintenance and monitoring.
Check the structural condition of the building regularly, deal with the parts with early cracks in time, and establish a structural health monitoring system to prevent problems before they happen.

Fourth, summary

Interlayer cracking is a problem that can't be ignored in construction engineering. Its causes are complex and it is difficult to deal with. Only by comprehensive consideration and scientific management in all stages of design, construction, use and maintenance can interlayer cracking be effectively prevented and treated. Only by strengthening quality control, optimizing design, standardizing construction and strengthening post-maintenance can the safety and durability of buildings be truly improved and people's lives and property be guaranteed.