Cracks in Prefabricated House Slabs

When cracks appear in the prefabricated slabs of a house, different treatment measures should be taken according to the condition of the cracks.

If there are few cracks, the gaps are small, and there is no liquid flowing on the floor, no repair may be necessary. Cracks of this degree have little impact on the structural safety of the house and do not pose a substantial threat to the overall stability and safety of the building. Therefore, no special repair work is required, and it is only necessary to regularly observe whether there are any changes in the cracks.

If the cracks are slightly larger and there is liquid leakage, immediate repair should be carried out. The specific repair steps are as follows:

• Chiseling the cracks: Chisel open the slab seams of the cracks, and chisel away 5 centimeters from each side of the surface layer to make the joint surface slope. At the same time, appropriately chisel the surface of the prefabricated floor slab and the sides of the slab to increase the bonding force between the newly poured material and the existing structure and improve the repair effect.
• Cleaning work: Clean up the debris and dust generated after chiseling the cracks to ensure that there are no foreign objects in the slab seams, creating good conditions for subsequent repair work.
• Applying cement mortar: Apply a layer of pure cement mortar inside the slab seams, with a water-cement ratio controlled between 0.4 and 0.5. Cement mortar can play a role in bonding and sealing, enhancing the strength and airtightness of the slab seams.
• Pouring and tamping fine aggregate concrete: Pour for the first time to half the depth of the slab seams. After the fine aggregate concrete absorbs water for a moment, carry out the second pouring until it is tamped and leveled 1 centimeter from the floor surface. During the pouring and tamping process, pay attention to vibrating it thoroughly to avoid defects such as cavities.
• Curing work: After the repair is completed, cure it for at least 2 - 3 days, and strictly prohibit others from stepping on it during this period. Curing allows the fine aggregate concrete to fully hydrate, improving its strength and durability.

There are also some precautions when dealing with cracks in prefabricated slabs. Avoid drilling holes in the prefabricated slabs to prevent affecting the load-bearing structure of the floor slab and reducing the safety of the house. If ceiling construction or other work needs to be carried out on the prefabricated slabs, pay special attention to construction safety and ensure that the hanging rods are installed in the seams between two prefabricated slabs. In addition, when renovating an old house, special attention will be paid to the issue of cracked prefabricated slabs in the later stage, such as applying mesh to enhance the overall integrity and crack resistance of the prefabricated slabs.