Prefabricated Floor Slab for Housing

Prefabricated floor slabs for housing are commonly used concrete prefabricated components in early 20th-century architecture. They are produced through standardized factory manufacturing and then assembled on-site, featuring simple structures and efficient construction. However, they have limitations such as weak earthquake resistance and poor sound and thermal insulation.

I. Definition and Manufacturing Process of Prefabricated Slabs

Prefabricated slabs are concrete components pre-fabricated in a factory. The manufacturing process involves first nailing wooden boards to create a hollow mold, placing steel reinforcement bars inside the mold, and then pouring concrete. After drying, the wooden boards are removed to form the finished product. Their core advantage lies in standardized production, enabling mass manufacturing and direct installation at construction sites, significantly shortening construction periods.

II. Types and Specifications of Prefabricated Slabs

1. Classification by Structure:

   • Solid Prefabricated Slabs: Made entirely of solid concrete, these slabs have strong load-bearing capacity but are heavy, suitable for areas requiring high structural strength.
   • Hollow Prefabricated Slabs: These slabs reduce the amount of non-load-bearing concrete through internal hollow designs, achieving lightweight while maintaining sufficient strength. They are more commonly used.

2. Dimensions:

   • Length: Standard lengths range from 3 meters to 4.2 meters, increasing in increments of 30 centimeters. The longest commonly used in ordinary residences is 4.2 meters, with custom lengths available for longer spans.
   • Width: Mostly 500 millimeters or 600 millimeters, facilitating tight joints during assembly.
   • Thickness: The standard thickness is 120 millimeters. If water pipes or electrical wires need to be embedded, a thickness of at least 150 millimeters is required to avoid damaging the structure.

III. Load-Bearing Grades and Application Scenarios of Prefabricated Slabs

Prefabricated slabs are classified into different grades based on their load-bearing capacity:

• Grade I Slabs: Have lower load-bearing capacity and are suitable for static load areas such as bedrooms.
• Grade II Slabs: Have higher load-bearing capacity and can be used in areas that may experience dynamic loads, such as living rooms and kitchens.
  In addition, prefabricated slabs are widely used in non-residential scenarios such as ditch covers beside highways and roof insulation layers.

IV. Limitations and Policy Orientation of Prefabricated Slabs

With the development of construction technology, prefabricated slabs are gradually being replaced by cast-in-place concrete and prefabricated buildings, mainly due to:

• Weak Earthquake Resistance: Their poor integrity makes them prone to fracture or displacement during earthquakes.
• Poor Sound and Thermal Insulation: The hollow structure results in insufficient sound insulation and thermal insulation performance.
• Limited Service Life: Typically lasting 30 to 50 years, they require regular maintenance.

Since 2022, China has implemented renovation policies, focusing on repair and renovation of prefabricated slab buildings and only demolishing those that meet the criteria for dangerous buildings, aiming to balance safety needs with resource utilization.