Concrete cracking is a common form of disease in housing diseases, and its appearance will not only reduce the impermeability of the house and affect the use function of the house, but also cause the rust of steel bars, the carbonization of concrete, reduce the durability of materials, and affect the bearing capacity of buildings.
Wall cracks are divided into the following three categories according to the causes caused:
1. Temperature cracks
Cracks caused by changes in temperature inside and outside the concrete. It often occurs in hydraulic large-volume concrete with poor heat dissipation conditions.
2. Settlement cracks
Uneven settlement of the foundation will cause the masonry to be pulled and sheared, creating cracks in the masonry.
3. Force crack
When the internal force generated by the load on the masonry structure is greater than the bearing capacity of the masonry structure, the cracks generated in the masonry structure are force cracks.
Cracks are patched
1) Surface closure method
For individual cracks or mesh cracks with a crack width of ω≤0.2 mm, the crack channel can be closed with a repair glue with good permeability (such as XQ Xin Ball edge banding glue). For floor slabs and other parts that need to be impermeable, it is advisable to paste fiber materials on the surface of the cracks to enhance the sealing effect.
2) Pressure perfusion method
For crack widths of 0.1mm≤ω≤1.5mm, low-viscosity structural adhesives (such as XQ-GF Xin ball grout glue) can be injected by pressure perfusion method for repair. The repair of cracks is mainly completed by embedding the nozzle, sealing the cracks, and filling the crack repair glue.
3) Pressure perfusion + paste carbon fiber cloth reinforcement
For cracks with a crack width of ω≥ 1.5 mm, and the cracks appear in the trans-intermediate region, it is determined to be a structural crack, and on the basis of pressure perfusion, a carbon fiber cloth is pasted along the vertical direction of the crack to increase the tensile bearing capacity of the structure.
The repair of concrete cracks can prevent the further development of cracks, and the concrete caused by further rust of steel bars continues to deteriorate. It has a significant effect on improving the durability of concrete. As a material for crack repair, its performance is directly related to the long-term performance of crack repair.