Prefabricated Floor Slab of House
Prefabricated floor slabs of houses were commonly used concrete prefabricated components in early 20th-century construction, enabling rapid construction through factory prefabrication followed by on-site installation. They have now been replaced by modern structural systems.
Manufacturing Process and Structural Types
The core manufacturing process for prefabricated floor slabs involves: nailing a hollow wooden mold → arranging steel reinforcement inside → pouring cement and curing → removing the mold to form the finished product. Their structures fall into two categories: solid and hollow. Hollow slabs reduce the amount of non-load-bearing concrete by core extraction or pre-formed holes, achieving lightweighting while maintaining load-bearing capacity. The weight of a single hollow slab is 30%-50% lower than that of a solid slab, facilitating transportation and lifting.
Application Scenarios and Historical Significance
This technology was widely applied in residential construction during the mid-to-late 20th century, with approximately 70% of China's residential buildings using prefabricated floor slab structures before 1985. Typical applications include:
- Horizontal load-bearing components: Serving as the structural layer for floors or roofs, directly bearing live loads such as furniture and personnel;
- Functional coverings: Non-load-bearing scenarios such as highway ditch covers and roof insulation layers.
Its advantages lie in standardized production, short construction periods, and low costs, aligning with the demands of large-scale housing construction at the time.
Reasons for Obsolescence and Existing Issues
With the development of construction technology, prefabricated floor slabs have gradually been replaced by frame structures and cast-in-place reinforced concrete structures, primarily due to:
- Insufficient structural safety: Node connections rely on welding or grouting, making them prone to disconnection under seismic action. The seismic performance of existing prefabricated slab buildings generally falls below the 6-degree fortification requirement;
- Limited durability: The concrete cover thickness is insufficient (typically only 15-20mm), leading to steel reinforcement corrosion. The design service life is mostly 30-50 years, far shorter than the 100-year standard for cast-in-place structures;
- Functional defects: The hollow structure results in poor sound insulation (weighted sound insulation level < 45dB) and weak thermal insulation (heat transfer coefficient > 2.0W/(㎡·K)), making it difficult to meet modern energy-saving requirements.
Renovation Recommendations
For existing prefabricated slab buildings, it is recommended to enhance performance through measures such as adding shear walls, carbon fiber reinforcement, and upgrading external insulation systems, but these must be implemented after evaluation by a professional institution. New construction projects now fully adopt cast-in-place or prefabricated concrete structures, addressing the inherent defects of traditional prefabricated slabs through integral pouring or reliable node connections.
