Production Flowchart of House Prefabricated Slabs

The production process of house prefabricated slabs is divided into two typical processes: traditional hollow prefabricated slabs and modern foam-core prefabricated slabs. The specific processes are as follows:

I. Production Process of Traditional Hollow Prefabricated Slabs

1. Model Making
   Use wooden planks to nail together a hollow model. The model dimensions must strictly conform to design requirements, with common specifications being a span of 4.2 meters, a width of 500/600 millimeters, and a thickness of 120/150 millimeters. The model must reserve space for the installation of the steel reinforcement framework to ensure compatibility with subsequent processes.

2. Steel Reinforcement Layout
   Lay out the steel reinforcement framework (distribution bars) in the hollow part of the model. The diameter and spacing of the steel bars must be determined based on design load calculations. The steel bars must fit snugly within the model space to prevent displacement during pouring.

3. Concrete Pouring
   Pour the prepared cement concrete into the model, filling the hollow part. During pouring, the concrete must be vibrated to ensure it is compacted and to prevent internal voids that could affect structural strength.

4. Curing and Demolding
   After the concrete has initially set, knock away the surrounding wooden planks to complete demolding. Traditional processes rely on natural curing, requiring the concrete to be left undisturbed for several days until it reaches the design strength.

Characteristics: The process is simple, but the hollow structure can lead to insufficient load-bearing capacity, and the natural curing period is long. It has gradually been replaced by cast-in-place structures.

II. Production Process of Modern Foam-Core Prefabricated Slabs

1. Mold Preparation
   Use steel plates to form a mold, tighten the screws to secure it, and then spray a release agent to prevent the concrete from sticking to the mold. The mold dimensions must be precisely controlled to ensure uniform finished product specifications.

2. Steel Reinforcement Framework Installation

   • Laying the First Layer of Distribution Bars: Hoist the steel bars from mid-air to ensure they fit tightly against the bottom of the mold.
   • Placing Foam Boards: Place large foam boards (occupying half the volume of the slab and 15 centimeters thick) on the steel bars. The foam boards are fixed with iron hooks to prevent them from floating during pouring.
   • Installing the Second Layer of Steel Bars and Steel Strands: Lay a second layer of steel reinforcement framework on the foam boards and thread high-strength steel strands (load-bearing bars) through them to form a composite load-bearing system.

3. Pretensioning Construction
   Use specialized equipment to stretch the steel strands to their ultimate strength (prestressed construction) before pouring the second layer of concrete. Prestressing technology can significantly enhance the slab's crack resistance and load-bearing capacity.

4. Vibration and Curing

   • Vibration to Remove Air Bubbles: Use a vibrator to remove air bubbles from the concrete to prevent honeycombing and pitting.
   • Steam Curing: Send the slab to a basement for 4 hours of steam curing to accelerate concrete hardening and shorten the production cycle.

5. Demolding and Finishing

   • After curing is complete, loosen the steel strands and lift the slab with a gantry crane.
   • Use an angle grinder to cut off the excess steel bars at both ends to complete the finished product.

Characteristics: The use of foam reduces the self-weight, and prestressing technology strengthens the structure, making it suitable for large-span buildings. However, the process is complex, and the equipment cost is high.