Installation of Precast Slabs for Prefabricated Houses

The installation of precast slabs for prefabricated houses should follow these key steps and considerations:

I. Preliminary Preparation and Surveying and Setting Out

Construction personnel should first conduct surveying and setting out, adjusting the height of independent supports according to design drawings, placing wooden beams as temporary supports, and using a tape measure to measure boundary dimensions and draw control lines to ensure accurate installation positions. This step is the foundation for subsequent installation and requires strict verification of dimensions to avoid cumulative errors.

II. Lifting and Positioning Installation

The precast slab is connected to the lifting device via hooks. Under the unified command of a signalman, it is slowly lifted to about 50 cm above the installation position and paused. After checking the stability of the lifting device, it is lowered further. Installation requirements include:

• Support Length: The support length on walls should be ≥ 90 mm, and on beams, it should be ≥ 60 mm to ensure safe load transfer.
• Slab Joint Treatment: When the joint width is ≤ 30 mm, it should be filled with fine aggregate concrete. When the joint width is > 30 mm, steel mesh reinforcement should be implanted, and anchor bars should be used to enhance overall integrity.
• Node Connection: For nodes between precast hollow slabs and bay beams, horizontal through-bars and X-shaped diagonal bars can be set in slots at the slab ends, and fine aggregate concrete can be poured to form a rigid connection. For modern pre-stressed concrete hollow slabs, nodes are reinforced by embedding steel bars to improve seismic performance.

III. Material Selection and Specification Adaptation

The type of precast slab should be selected according to project requirements:

• Flat Slabs: Suitable for areas with small spans and no special load requirements.
• Channel Slabs: Provide additional rib support to enhance flexural capacity.
• Hollow Slabs: The mainstream choice due to their light weight and cost-effectiveness. The standard span is up to 4.2 meters, with widths mostly being 500 mm/600 mm and common thicknesses of 120 mm/150 mm. Before materials enter the site, their certificates of conformity and performance test reports should be checked to ensure that their strength and durability meet design requirements.

IV. Construction Process Control

Taking pre-tensioned pre-stressed concrete hollow slabs as an example, the process includes:

1. The prefabricated pedestal should be made with a flatness error ≤ 2 mm.
2. After installing steel strands and reinforcing bars, pre-tensioning should be carried out to eliminate elastic deformation.
3. The formwork should be tightly sealed to prevent concrete leakage.
4. After concrete pouring, it should be covered and cured for ≥ 14 days, and the release of pre-stressed tendons should be completed in stages.
5. When moving and stacking slabs, the number of layers should not exceed 3, and the integrity of components should be checked before lifting.

V. Advantages, Disadvantages, and Improvement Directions

Advantages: The construction period is shortened by 30%-50%, quality stability is improved (with errors controlled within ± 2 mm), and material utilization is increased by 15%-20%. Disadvantages: Traditional precast slabs have relatively weak seismic performance, are prone to cracking and leakage due to temperature shrinkage, and have limited flexibility in spatial layout. Improvement Measures: Modern pre-stressing techniques can be used to enhance node connections, post-pouring strips can be set to solve leakage problems, and BIM technology can be combined to optimize the layout plan of precast slabs and improve spatial adaptability.