Prefabricated Hollow Slab House Construction

The construction of prefabricated hollow slab houses requires strict control over aspects such as slab selection, base treatment, slab joint support, installation and connection, and process control to ensure structural safety and performance compliance.

1. Prefabricated Hollow Slab Selection and Characteristic Adaptation

Select the appropriate type based on the house design requirements:

• Traditional Hollow Slabs: Suitable for low-rise buildings, with limited load-bearing capacity and requiring attention to span limitations.
• SP Slabs (Prestressed Hollow Slabs): Can span up to 12 meters, with a light self-weight and superior seismic performance compared to non-prestressed slabs, making them suitable for multi-story buildings.
• EHC Slabs (Extruded Prestressed Slabs): Recommended by the 2025 national standard drawings, with a maximum span of 20 meters, utilizing high-strength concrete and prestressing technology, suitable for large-span or high-rise buildings.
  Key Point: Select the slab type based on load, span, and seismic requirements to avoid out-of-range use.

2. Base Treatment and Installation Preparation

• Wall Top Surface Treatment: Wet the wall top surface one day in advance to avoid standing water; use M15 or higher cement mortar for leveling, with a thickness controlled between 20-30mm, ensuring a flatness error of ≤5mm.
• Prohibited Operations: Do not use broken bricks, wooden blocks, etc., for leveling to prevent local stress concentration leading to slab joint cracking.
• Temporary Support Setup: Within 7 days after installation, set up wooden beams or steel pipe supports at the slab bottom, with a spacing of ≤1.5 meters, and remove them after the concrete strength reaches 75% of the design value.

3. Slab Joint and Connection Reinforcement

• Slab Joint Treatment:
  • Ordinary slab joints: Fill with C20 fine aggregate concrete, with a width of ≥30mm, poured in two layers and vibrated densely.
  • When load increases: Reinforce by pasting carbon fiber sheets at the slab bottom, with a single-layer thickness of ≥0.167mm and a width covering 200mm on both sides of the slab joint.
• Integral Connection:
  • Prefabricated slab and wall: Connect by welding or binding pre-embedded steel bars (Φ8@600) and fill the gaps with C20 concrete.
  • Slab-to-slab connection: Reserve a gap of 10-15mm, embed steel mesh (φ6@300), and pour concrete.

4. Cast-in-Place Hollow Floor Process Control (Example)

1. Surveying and Setting Out: Use a laser level to determine the slab bottom elevation and mark the support positions with chalk lines.
2. Formwork Setup: Use 18mm thick plywood with wooden joists spaced at ≤300mm, and reserve 4 iron wires per square meter to fix the internal formwork.
3. Internal Formwork Placement: Bury high-strength thin-walled tubes (diameter 150-300mm) with a spacing of ≤500mm, and fix them with iron wires to prevent floating.
4. Rebar Binding and Pouring: Bind double-layer bidirectional rebars (φ10@150), control the concrete slump between 160-180mm, pour in layers and vibrate densely, and cure for ≥14 days.

5. Quality Monitoring and Precautions

• Prohibit Shoddy Workmanship: Behaviors such as failing to level the wall top or not setting up temporary supports will lead to structural safety hazards.
• Load Adaptability: If additional floors or equipment loads are required, entrust a professional institution to conduct a load-bearing capacity review.
• Standardized Construction: The cast-in-place process must strictly follow the "Technical Specification for Cast-in-Place Concrete Hollow Floor Systems" to ensure compliance with sound insulation and thermal insulation performance.