Precast Slabs in Housing Architecture

Precast slabs were commonly used floor components in early 20th-century architecture, prefabricated in factories and assembled on-site. They were widely applied in residential buildings, insulation layers, and infrastructure but have gradually been replaced by cast-in-place structures due to issues such as poor earthquake resistance.

Definition and Manufacturing Process of Precast Slabs

Precast slabs are concrete modules prefabricated in factories or on-site prefabrication yards, primarily used as floor or roof slabs. The manufacturing process involves first nailing wooden hollow molds, arranging steel bars inside the molds, and then pouring cement. After the concrete solidifies, the wooden boards are knocked off, forming precast slabs with hollow or solid structures. The hollow structure achieves lightweighting by reducing non-load-bearing concrete, lowering material costs and减轻 (lightening, here it should be 'reducing') the self-weight of the floor slabs. However, it is essential to ensure that the hollow positions do not bear structural loads.

Types and Applications of Precast Slabs

Precast slabs are divided into two types: solid and hollow. Hollow precast slabs, due to their light weight and low cost, were widely used in urban residential floor slabs and roof insulation layers from the 1970s to the 1990s. Solid precast slabs are mostly used in scenarios with high load-bearing requirements. In addition to residential buildings, precast slabs are also applied in infrastructure such as highway ditch covers and temporary building insulation layers. Precast slab houses are a form of architecture with precast slabs as the main components. The walls are mostly brick or prefabricated concrete wall panels, with a brick-concrete structure. They feature fast construction speed and low cost and were once the mainstream choice for affordable housing.

Limitations of Precast Slab Buildings

With the development of architectural technology, the defects of precast slab buildings have gradually become apparent:

1. Weak Earthquake Resistance: The connection nodes between precast slabs and walls are prone to damage during earthquakes, leading to floor slab collapse. The earthquake resistance of existing precast slab houses generally does not meet standards.
2. Poor Sound Insulation and Thermal Insulation: The hollow structure results in insufficient sound insulation performance. The poor thermal conductivity of concrete leads to heat accumulation in summer and heat dissipation in winter.
3. Limited Service Life: Precast slab houses are designed with a service life of approximately 30-50 years. After long-term use, problems such as structural aging and component corrosion are prominent.
4. Low Spatial Flexibility: The fixed size of precast slabs makes it difficult to adapt to the modern architectural demand for large spans and personalized spaces.

Alternative Technologies and Existing Issues

Cast-in-place concrete structures significantly improve the overall integrity and earthquake resistance of buildings through on-site integral pouring and have become the mainstream choice. Prefabricated buildings adopt modular prefabricated components (such as steel-concrete composite modules), shortening the construction period by 30% and improving quality stability through standardized design. Currently, some regions have initiated the demolition of precast slab houses, focusing on renovating old residential buildings built before 1985 to eliminate safety hazards.