Prefabricated Floor Slab for Concrete Houses

The prefabricated floor slab for concrete houses is a building component that is pre-fabricated in a prefabrication yard or factory and then transported to the construction site for installation. It features standardization, efficiency, and cost-effectiveness, but has limited spatial flexibility.

Types and Specifications

Commonly used prefabricated reinforced concrete slabs are classified into flat slabs, channel slabs, and hollow slabs based on their cross-sectional forms. Taking YKB3606-8a as an example, it is 3.6 meters long, 0.6 meters wide, with a characteristic thickness of 120 millimeters, 8 main reinforcement bars, and 5 holes (with a hole diameter of 76 millimeters and a center spacing of 105 millimeters). The actual width at the bottom of the slab is 59 centimeters. The specifications are designed to be standardized, with lengths typically being multiples of 300mm, widths multiples of 100mm, and thicknesses ranging from 120 to 300mm, meeting the needs of different spans.

Advantages and Disadvantages

Advantages:

1. Material Savings: The prestressing process can reduce steel usage by 30% to 50% and concrete usage by 10% to 30%, while improving crack resistance and enabling large spans with thin slabs.
2. Efficient Construction: Industrial production shortens the construction cycle, ensures stable quality, and improves material utilization.
3. Cost-Effectiveness: Standardized design reduces overall costs and is suitable for large-scale applications.

Disadvantages:

1. Spatial Limitations: The layout flexibility is poor, and the overall integrity is weaker than that of cast-in-place slabs, making it difficult to create openings or make modifications.
2. High Connection Requirements: Strict treatment of slab joints and reinforcement is required; otherwise, it may affect the overall structural integrity.

Installation Requirements

1. Support Length: The wall support should be no less than 90mm, and the beam support should be no less than 60mm. When encountering structural columns, additional slab strips should be added.
2. Slab Joint Treatment:
   • For joint widths less than 30mm: Fill with fine aggregate concrete.
   • For joint widths between 50 and 120mm: Add steel mesh and then fill with concrete; for 120mm joints, fill with bricks against the wall.
   • For joint widths greater than 120mm: Use a reinforced concrete slab strip with a steel framework. Double-toothed joints (such as channel slabs) can enhance overall stiffness.
3. Reinforcement Treatment: Before installation, seal the holes and bend the reinforcement upwards; after lifting, bend it downwards at a 45-degree angle and add continuous reinforcement. In earthquake-prone areas or on soft soil foundations, anchor reinforcement should be provided.
4. Layout Method: Choose between slab-type (directly placed on walls) or beam-slab-type (supported on beams) layouts based on the space size and specification uniformity. Calculate the number of slabs in advance and draw installation diagrams.

Applications and Prices

Application Cases: Projects such as the Oodi Central Library in Helsinki, Finland, and the V&A Waterfront Parking Garage in Cape Town, South Africa, have adopted prefabricated floor slabs, demonstrating their advantages in large-span and rapid construction scenarios.
Market Prices: A 12-centimeter-thick prestressed hollow slab costs approximately 18 yuan per meter, while a wear-resistant cement prefabricated slab costs about 49 yuan per piece. Prices vary significantly depending on specifications, materials, and uses.