Prefabricated Floor Slab for House Construction

A prefabricated floor slab for house construction is a concrete prefabricated component produced and processed in a prefabrication yard, which is directly transported to the construction site for installation as a floor structure. Here is a detailed introduction to prefabricated floor slabs:

I. Definition and Production
Prefabricated floor slabs were a commonly used floor form in early 20th-century architecture, belonging to engineering modules or panels. The production process involves first nailing a hollow mold with wooden planks, arranging steel bars in the hollow part of the mold, filling the hollow part with cement, knocking off the wooden planks after drying, and finally forming a prefabricated floor slab. This industrial production method gives it standardized characteristics.

II. Types and Specifications
Prefabricated floor slabs are divided into two types: solid and hollow. The hollow structure achieves lightweighting by reducing the concrete in non-load-bearing parts. Their size specifications have the following characteristics:

• Span: The longest for residential use is 4.2 meters, and customization is required for spans exceeding this length.
• Width: Mainly 500mm and 600mm.
• Thickness: Commonly 120mm and 150mm.
• Length: Produced according to a 300mm modulus, such as 3000mm, 3300mm, etc. Special specifications like 3800mm and 4000mm can also be customized.
• Load-bearing grade: Generally, Grade I slabs (1kN/m²) and Grade II slabs (2kN/m²) are used for residential buildings. In the southwest region, the minimum is specified as Grade IV slabs (4kN/m²).

III. Advantages and Disadvantages Analysis
Advantages:

• Construction period and cost advantages: Industrial production shortens on-site construction time and reduces overall costs.
• Application flexibility: Can be used in various scenarios such as highway ditch covers and roof insulation layers.

Disadvantages:

• Insufficient structural safety: The spliced design lacks integrity, and the steel bar distribution in the hollow structure is not as reasonable as that in cast-in-place buildings. During earthquakes, the joints are prone to loosening, which may even lead to building collapse.
• Poor durability: With a service life of about 30-50 years, aging can lead to problems such as cracks and water leakage, with high repair costs.
• Performance defects: Poor thermal insulation results in cold winters and hot summers, poor sound insulation, and walls are prone to cracks due to thermal expansion and contraction.

IV. Development Status
Prefabricated floor slab buildings originated in the early 20th century. In China, most residential buildings constructed before 1985 used this type of structure. With the advancement of building technology, cast-in-place concrete and prefabricated buildings have gradually replaced traditional prefabricated floor slab houses. Since 2022, China has implemented a renovation policy, focusing on repairing and renovating prefabricated floor slab houses and only demolishing those that meet the criteria for dangerous buildings.