Treatment of Cracks in the Joints of House Prefabricated Panels

The treatment method for cracks in the joints of house prefabricated panels should be determined based on the crack conditions and the stage of renovation.

Treatment of Horizontal Cracks

• Observe the crack conditions: When horizontal cracks appear in the joints of prefabricated panels, if the number of cracks is small, the gaps are narrow, and there is no liquid flowing on the floor, such cracks have little impact on the structural safety of the house and may not require repair. This is because cracks of this degree usually do not cause substantial damage to the overall stability and load-bearing capacity of the house and do not affect its normal use.
• Immediately repair larger cracks: If the cracks are slightly larger and there is liquid leakage, they should be repaired immediately. The repair steps are as follows:
  • Chisel the joint: Chisel open the joint with the crack, remove 5 cm of the surface layer on both sides to make the joint surface slope, and appropriately roughen the surface of the prefabricated floor slab and the side of the panel, then clean it up. The purpose of this is to increase the contact area between the newly poured material and the existing structure and improve the bonding strength.
  • Brush cement mortar: Brush a layer of pure cement mortar inside the panel joint, with a water-cement ratio controlled between 0.4 and 0.5. Cement mortar can serve as a bonding and transitional layer, providing a good foundation for the subsequent pouring of fine aggregate concrete.
  • Pour fine aggregate concrete: Pour the fine aggregate concrete to half the depth of the panel joint for the first time. After the fine aggregate concrete absorbs water for a moment, pour it a second time until it is compacted and leveled 1 cm from the panel surface. Pouring in two batches can make the fine aggregate concrete denser, reduce internal voids, and improve the repair quality.
  • Curing: After the repair is completed, cure it for at least 2-3 days, during which no one is allowed to step on it. Curing is to allow the fine aggregate concrete to fully hydrate and reach the designed strength. At the same time, when dealing with cracks in prefabricated panels, avoid drilling holes in the prefabricated panels to prevent affecting the load-bearing structure of the floor slab. If ceiling installation or other construction work needs to be carried out on the prefabricated panels, pay special attention to construction safety and ensure that the hanging rods are installed in the joints between two prefabricated panels.

Crack Treatment during Re-renovation

During later re-renovation, for cracks in the joints of prefabricated panels, only Dacron cloth or mesh cloth can be used for treatment. First, fill the gaps as much as possible, and then add carbon fiber cloth on the outside. This can enhance the tensile strength at the crack location, prevent the cracks from expanding again, and also serve a certain decorative function, making the renovation effect more aesthetically pleasing.