Installation of Prefabricated Slabs for House Chimneys

The installation of prefabricated slabs for house chimneys should follow the steps below to ensure construction standards and structural safety:

I. Prefabricated Platform Construction

Construct a prefabricated platform in the chimney prefabrication yard using 100×100mm wooden beams and composite steel formwork, with platform dimensions of 10×20m. The platform must meet load-bearing capacity requirements to ensure no settlement or deformation occurs during prefabrication. Prefabricate 19 slabs each time, completing all 38 slabs (including 4 irregularly shaped slabs) in two batches. After platform construction, check the flatness, with an error tolerance of ±2mm, to prevent slab thickness deviations due to uneven bases.

II. Prefabricated Slab Construction Process

1. Lay Prefabricated Bottom Formwork: Lay steel formwork on the platform as the bottom formwork, and use sealing strips at the joints to prevent concrete leakage.
2. Projection Layout: According to the design drawings, mark the outline and reinforcement positions of the prefabricated slabs on the bottom formwork to ensure accurate dimensions.
3. Reinforcement Binding: Bind the reinforcement framework according to design requirements, with main reinforcement diameter not less than Φ10mm and stirrup spacing ≤150mm. Adjust the reinforcement layout for irregularly shaped slabs based on their shape.
4. Formwork Installation and Reinforcement: Install side formwork and reinforce with tie rods. The side formwork height should be 10mm higher than the slab thickness to reserve space for concrete vibration.
5. Concrete Pouring: Use commercial concrete with a strength grade of C30 or above, and vibrate in layers to ensure compactness and avoid honeycombing and pitting.
6. Surface Treatment: Smooth and polish the concrete surface before initial setting to ensure surface flatness ≤3mm.

III. Curing and Formwork Removal Requirements

After slab pouring, cover with plastic film and water cure for 14 days to keep the surface moist. During formwork removal, the concrete strength should reach 80% or more of the design strength (detected by a rebound hammer), using a 20t crane with lifting fixtures. Continue curing until 28 days after formwork removal. When stacking, use wooden beams as spacers, with each stack height not exceeding 6 slabs to prevent cracking due to self-weight.

IV. Mechanical Hoisting Installation

Use a 20t truck crane to hoist the prefabricated slabs from the flue opening to the installation position. Before hoisting, verify the internal dimensions of the chimney to ensure alignment between the prefabricated slabs and the smoke wall slots. Follow the installation sequence of "bottom-up, straight-first, irregular-last," and precisely position irregularly shaped slabs according to their numbers. Designate a person to direct during hoisting to avoid collision with the chimney inner wall, and check the verticality deviation ≤5mm after installation.

Precautions: Prepare a special work instruction before construction to clarify technical parameters for each step; operators must be certified and strictly adhere to safety regulations; suspend hoisting operations in windy, rainy, or snowy weather.