Deformation and Falling of Prefabricated House Slabs
The deformation and falling of prefabricated house slabs may be caused by factors such as excessive load, moisture-induced carbonation, and weak seismic performance.
Excessive Load: The overall integrity of prefabricated slab structures is relatively poor. The floor slabs are placed piece by piece on brick walls, with no overall connection between the slabs. Although the slab joints are filled with mortar, each slab bears loads independently and cannot share the load with others. When the temporarily accumulated load on the second-floor slab exceeds the bearing capacity of the prefabricated slabs, brittle fracture of the slab may occur, leading to its falling. For example, in some old houses, residents may stack a large amount of heavy objects on the floor slabs to increase storage space, which can easily trigger such problems.
Moisture-Induced Carbonation: Once the prefabricated slabs are exposed to moisture, the problems will accelerate. The roof waterproofing layer will experience fatigue over time, and cracks may easily form in areas such as bathrooms and kitchens, allowing water to seep from one household to another. Prefabricated slabs that are exposed to moisture for a long time are prone to carbonation, and the steel bars inside will gradually rust. After the steel bars rust, their bond strength with the concrete decreases, and the effective cross-sectional area of the steel bars is reduced, resulting in a gradual decrease in the load-bearing capacity of the prefabricated slabs and ultimately possibly causing deformation and falling. For example, in some older houses that have been poorly maintained for a long time, the roof waterproofing fails, causing the prefabricated slabs to be in a humid environment for a long time, and such situations are prone to occur.
Weak Seismic Performance: Prefabricated slab structures are inherently weak in terms of seismic performance. When they were built in the past, the seismic fortification standards were mostly only 6 degrees, while newly built residential buildings now generally require seismic standards of 7 to 8 degrees. During an earthquake, the joints between the prefabricated slabs are prone to cracking and dislocation, and in severe cases, the floor slabs may fall off entirely. For example, in some earthquake-prone areas, some old prefabricated slab houses have suffered severe damage such as slab falling during earthquakes.
