Transverse Cracks in Prefabricated House Slabs
Transverse cracks appear in the prefabricated slabs of the house, and different treatment measures need to be taken according to the crack conditions.
The appearance of transverse cracks in the prefabricated slabs of the house may be related to horizontal stress. Common causes include uneven foundation settlement, expansion and contraction caused by temperature changes, or the influence of horizontal loads (such as wind loads and seismic effects). In horizontal members such as beams and slabs, transverse cracks may also be caused by bending moments.
If there are few cracks and the gaps are small, and there is no liquid leakage on the floor, repairs can be temporarily postponed. Such cracks usually have limited impact on the structural safety of the house, but their development still needs to be regularly observed. If the cracks do not continue to expand or deepen, the current situation can be maintained; if there are abnormal changes, further measures need to be taken in a timely manner.
If the cracks are slightly larger and there is liquid leakage, immediate repairs are required, with the following specific steps:
- Chiseling the cracks: Chisel open the cracks in the slab, 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 side of the slab to ensure that the repair material fully adheres to the original structure. Finally, clean up the chiseled debris and dust.
- Pouring fine aggregate concrete: Brush a layer of pure cement mortar inside the slab cracks, with a water-cement ratio controlled between 0.4 and 0.5. Immediately pour fine aggregate concrete, pouring it to half the depth of the slab cracks for the first time; after the fine aggregate concrete absorbs water for a moment, pour it for the second time until it is compacted and leveled 1 centimeter from the floor surface to ensure a flat and dense repair surface.
- Curing and protection: After the repair is completed, cure it for at least 2-3 days. During this period, no one is allowed to tread on it or apply loads to ensure that the fine aggregate concrete fully hardens and reaches the design strength.
The following matters need to be noted when dealing with cracks: Avoid drilling holes in the prefabricated slabs to prevent damaging the load-bearing structure of the floor slab and affecting overall safety; if ceiling construction or other work needs to be carried out on the prefabricated slabs, ensure that the hanging rods are installed in the joints between two prefabricated slabs and take reinforcement measures to prevent local stress concentration from causing crack expansion.
