Removal and Reinforcement of House Prefabricated Slabs

The removal and reinforcement of house prefabricated slabs should follow scientific procedures and standards, involving key aspects such as structural assessment, construction preparation, reinforcement treatment, and policy compliance.

I. Structural Safety Assessment Before Removal

1. Crack Detection: Focus on inspecting the crack width at the production points of the prefabricated slabs. If the width exceeds 0.3 millimeters, special treatment (such as grouting reinforcement or carbon fiber cloth reinforcement) is required to prevent crack propagation and structural failure.
2. Connection Status Inspection: Check the rust rate of the connecting bolts between the prefabricated slabs and the ring beams. If the rust rate exceeds 30%, replacement is mandatory to ensure the load-bearing capacity of the connection nodes.
3. Overall Safety Determination: Have the structural safety grade of the house assessed by a professional institution. If it is classified as a C-grade or D-grade dilapidated building, decisions on removal or reinforcement should be made in accordance with policies.

II. Construction Preparation and Temporary Support System

1. Support System Construction: Set up steel pipe supports every 1.2 meters along the length of the prefabricated slabs. Use H-shaped steel beams (with a cross-section of at least 200*200 millimeters) for underpinning at key nodes to ensure that the floor slab does not sink during removal.
2. Material and Equipment Preparation: Prepare tools such as No. 6 deformed steel bars, C30 fine aggregate concrete, electric welders, and cutting machines. Clear the construction area to ensure sufficient working space.

III. Reinforcement Treatment and Construction Sequence

1. Slab Joint Reinforcement: Remove the original filling materials, implant No. 6 deformed steel bars, and then pour C30 fine aggregate concrete to enhance the shear resistance of the slab joints.
2. Constructional Column Addition: Add 240*240-millimeter constructional columns at the four corners of the house. Use No. 6 and No. 8 steel bars for reinforcement and connect them to the floor slab to improve the overall seismic performance.
3. Segmented Removal Principle: Follow the principle of "removing from the middle first, then the sides, and symmetrically" with a daily removal volume not exceeding 30% of the total floor slab area to avoid local overloading.
4. Real-time Monitoring: Monitor the stress changes in the support system during removal. Prohibit the use of heavy hammers for impact removal to prevent damage to the foundation.

IV. Policy Compliance and Renovation Directions

1. Classification and Disposal Principle: According to the 2025 urban renewal policy, structurally safe prefabricated slab houses should be prioritized for reinforcement and renovation (such as functional upgrades and refurbishment). Only D-grade dilapidated buildings that cannot be repaired should be demolished and rebuilt.
2. "Preservation, Renovation, and Removal" Model: The 2026 "15th Five-Year Plan for Urban Renewal" explicitly prohibits large-scale demolition and construction. Existing prefabricated slab buildings will uniformly follow the "preservation, renovation, and removal" tripartite governance approach, with structurally intact buildings preserved and renovated, those with local hazards repaired and reinforced, and severely damaged ones included in the removal scope.

V. Precautions The construction should be carried out by qualified units and strictly comply with standards such as the "Code for Design of Building Structural Loads" to ensure that the reinforced house meets safety requirements for seismic resistance and load-bearing capacity.