Reinforcement and Renovation of Prefabricated Slab Houses
The reinforcement and renovation of prefabricated slab houses can be achieved through measures such as structural assessment, roof renovation, exterior wall treatment, temporary support, slab joint treatment, adding structural columns, standardizing construction sequence, and adding beams under the slabs. Details are as follows:
1. Structural Safety Assessment and Treatment Before renovation, a comprehensive structural safety assessment of the house is required, focusing on inspecting the crack width and connection status of the prefabricated slabs. If the crack width exceeds 0.3 millimeters, pressure grouting or carbon fiber cloth reinforcement should be used. If the rust rate of the connecting bolts between the prefabricated slabs and the ring beams exceeds 30%, they should be replaced with high-strength bolts to ensure the stability of the connection nodes.
2. Roof Renovation Remove the original wooden roof and, while maintaining the original building height, recast a concrete roof. The concrete should have a grade of C30 or above and be equipped with a double-layer bidirectional steel reinforcement mesh to enhance the overall integrity of the roof. After renovation, the roof can meet the requirements for waterproofing and thermal insulation, while providing a stable base for subsequent laying of tiles, photovoltaic panels, etc.
3. Exterior Wall Treatment After removing the original exterior wall tiles, two-step treatment is required: Reinforcement with Embedded Bars and Grouting, where No. 6 threaded bars are embedded every 500 millimeters along the height of the wall, with a depth of not less than 150 millimeters, and high-strength grouting material is poured; Re-plastering, where anti-crack mortar is used for leveling, followed by hanging a steel wire mesh and applying waterproof coating to improve the tensile strength and durability of the wall.
4. Temporary Support System Construction Before construction, steel pipe supports should be installed every 1.2 meters along the length of the prefabricated slabs, with key nodes supported by H-section steel beams with a cross-section of not less than 200×200 millimeters. The support system should be reliably connected to the original structure and monitored in real-time with stress monitoring equipment to ensure structural safety during construction.
5. Slab Joint Treatment After removing the original filling material from the slab joints, No. 6 threaded bars (spaced 200 millimeters apart) should be embedded, and C30 fine aggregate concrete should be poured. The concrete should be added with a micro-expansion agent to reduce shrinkage cracks and covered with moisture-retaining curing for not less than 14 days to improve the shear resistance of the slab joints.
6. Adding Structural Columns Add structural columns at key locations such as the corners of the house and stairwells, with a cross-section of 240×240 millimeters. The longitudinal reinforcement should be a combination of No. 6 and No. 8 bars, with stirrups spaced 200 millimeters apart. The structural columns should form an integral frame with the floor slabs and ring beams, significantly improving the seismic performance of the house.
7. Construction Sequence and Demolition Methods Demolition should follow the principle of 'middle first, then sides', with a daily demolition volume not exceeding 30% of the total floor slab area, and symmetric demolition should be maintained to reduce eccentric loads. The use of heavy hammers for impact demolition is prohibited to avoid impacting the foundation; after demolition, the debris should be immediately cleared to prevent local overloading.
8. Adding Beams Under the Slabs If the load increase is small, carbon fiber cloth (200 millimeters wide, spaced 300 millimeters apart) can be pasted under the hollow slabs; if the load increase is large, steel beams (such as H200×100×6×8) should be added, which are connected to the wall with chemical anchors to change the force mode of the hollow slabs and improve their load-bearing capacity.
