Prefabricated Floor Slab for Houses

Prefabricated floor slabs for houses were a commonly used floor form in early 20th-century architecture, enabling rapid construction through factory prefabrication and on-site installation, but they have limitations such as weak earthquake resistance and poor sound and thermal insulation.

Manufacturing Process and Types

Prefabricated floor slabs are produced in a factory-based mode: First, a hollow mold is made by nailing wooden boards. Reinforcing bars are then arranged inside the mold, and concrete is poured. After the concrete dries, the wooden boards are knocked off, forming standardized slabs. Depending on structural differences, they can be divided into two types: solid and hollow. Hollow prefabricated slabs achieve lightweighting by reducing the amount of concrete in non-load-bearing parts, lowering material costs while ensuring load-bearing capacity.

Application Scenarios and Advantages

In the 1970s and 1980s, a large number of five- to six-story residential buildings in China adopted prefabricated floor slabs. Their core advantage lies in high construction efficiency. Cast-in-place floor slabs require waiting for the concrete to dry completely (about 15 days), while prefabricated floor slabs can complete the construction of one floor in 3 days through on-site assembly. In addition, they have a wide range of applications. Besides residential floor slabs, they can also be used for non-load-bearing or low-load-bearing scenarios such as highway ditch covers and roof insulation layers.

Defects and Limitations

1. Insufficient structural performance: Existing prefabricated slab houses generally have the problem of weak earthquake resistance. The connection methods between slabs, such as steel bar welding or concrete filling, are difficult to withstand strong earthquake impacts. They also have poor sound and thermal insulation performance, requiring additional insulation layers or soundproofing materials.
2. Limited service life: The designed service life of prefabricated floor slabs is about 30-50 years. After long-term use, problems such as steel bar corrosion and concrete carbonation are prone to occur, leading to a decrease in structural bearing capacity.
3. Low design flexibility: The house layout needs to strictly match the sizes of prefabricated slabs (e.g., common specifications are 3.3 meters and 3.6 meters), resulting in rigid spatial layouts that are difficult to meet the needs of modern living.
4. High risk of leakage: Cracks are prone to form at the joints between slabs due to material shrinkage or construction defects, becoming the main channels for rainwater leakage.

Modern Alternatives and Policy Orientation

With the progress of construction technology, cast-in-place concrete (with strong integrity and good earthquake resistance) and prefabricated buildings (with modular design and precise construction) are gradually replacing traditional prefabricated floor slabs. Since 2022, China has implemented a policy of renovating old buildings, focusing on repairing and renovating prefabricated slab houses and only demolishing buildings identified as dangerous. The emphasis is on solving problems such as leakage and structural reinforcement to extend their service life.