Prefabricated Floor Slab in Building Architecture

Prefabricated floor slabs were widely used as modular floor forms in early 20th-century architecture. Manufactured off-site and assembled on-site, they offered high construction efficiency and low costs but faced limitations in earthquake resistance, durability, and flexibility, gradually being replaced by cast-in-place concrete and prefabricated buildings.

I. Types and Manufacturing Process of Prefabricated Floor Slabs

Prefabricated floor slabs come in two main types: solid slabs and hollow-core slabs. Hollow-core slabs achieve lightweighting by reducing non-load-bearing concrete, lowering material costs and structural deadweight. Their manufacturing process involves:

1. Formwork Fabrication: Wooden planks are nailed together to create hollow molds with reserved spaces for steel reinforcement.
2. Reinforcement Placement and Pouring: Steel bars are laid in the hollow sections of the molds, followed by cement pouring and compaction.
3. Stripping and Curing: After the cement sets, the wooden planks are removed, resulting in standardized prefabricated components.

II. Technical Characteristics and Limitations

1. Earthquake Resistance:
   • Some prefabricated slab buildings survived the Tangshan Earthquake, but joint areas were prone to cracking under vibration, requiring regular inspections for steel corrosion and joint sealing.
   • Traditional prefabricated slabs had poor integrity, making them susceptible to displacement during earthquakes. Modern prefabricated buildings enhance seismic performance through steel-concrete monolithic pouring.
2. Durability:
   • Existing prefabricated slab houses have a lifespan of approximately 30-50 years, commonly suffering from poor sound and thermal insulation, which can be improved with additional insulation layers or soundproofing materials.
   • Joints are prone to water leakage due to material aging, necessitating treatment with waterproof tape or sealants.
3. Construction Constraints:
   • Rigid Unit Design: Strict matching with prefabricated slab dimensions limits complex spatial layouts.
   • Reduced Construction Cycle Advantage: Early prefabricated slab buildings could assemble one floor in three days, while cast-in-place floors required半个月 of cement drying. However, modern prefabricated construction reduces the cycle by 30% compared to traditional methods, offering greater flexibility.

III. Application Scenarios and Replacement Trends

1. Traditional Applications:
   • Non-load-bearing structures such as roadside ditch covers and roof insulation layers.
   • Mainstream floor form for five- to six-story residential buildings in the 1970s-80s due to rapid construction speeds.
2. Modern Alternatives:
   • Cast-in-Place Concrete: Offers strong integrity, suitable for high-rise buildings and scenarios with high seismic requirements.
   • Prefabricated Buildings: Utilize factory-prefabricated components like CMC composite modules, enhancing structural stability through steel-concrete connections and improving construction efficiency.
3. Policy Guidance:
   • Since 2022, China has implemented renovation policies focusing on repairing and upgrading prefabricated slab houses, demolishing only those meeting hazardous building standards, with a focus on addressing sound and thermal insulation and water leakage issues.

As a representative of early building industrialization, prefabricated floor slabs hold significant historical value, but their technical limitations have driven the industry toward more efficient and safer modern construction methods.