Prefabricated Housing for Secondary Structures

Prefabricated housing for secondary structures involves using prefabricated components to complete the construction of secondary structures in buildings, offering advantages such as convenient construction and controllable quality. The following provides an introduction from three aspects: types of prefabricated components, typical application scenarios, and key points for connection construction.

I. Common Types of Prefabricated Components for Secondary Structures
The mainstream prefabricated components for secondary structures on the market include steel floor slab formwork-free panels, ALC (Autoclaved Lightweight Concrete) prefabricated concrete panels, new steel structure wall panels, and lightweight partition panels. Steel floor slab formwork-free panels are factory-prefabricated with a composite structure of steel frames and concrete, eliminating the need for additional formwork during on-site installation and shortening the construction period. ALC prefabricated concrete panels (autoclaved aerated concrete panels) are made from raw materials such as cement, lime, and silica sand, featuring lightweight, high strength, and fire-resistant and heat-insulating properties. Their density is only one-fifth that of ordinary concrete, and their fire resistance limit can reach 3-6 hours. New steel structure wall panels use a composite of cold-formed thin-walled steel frames and lightweight filling materials, suitable for non-load-bearing partitions and enabling rapid assembly and disassembly. Lightweight partition panels (such as gypsum hollow panels and fiber-reinforced cement panels) reduce self-weight by adding lightweight aggregates or fiber materials while meeting requirements for sound insulation and moisture resistance.

II. Typical Application Scenarios
Prefabricated components are mainly used in two types of scenarios in secondary structures: First, formwork replacement in plastering and blocking projects, such as for structural columns and lintels. Traditional construction requires on-site formwork erection and removal, whereas prefabricated blocking panels can be directly used as formwork, reducing wet work volume. Second, floor slab and wall systems, such as using ALC panels for infill walls, steel floor slabs for inter-floor separation, and lightweight partition panels for interior partitions. These components are produced to standardized factory specifications with dimensional accuracy up to ±2mm, minimizing on-site assembly errors and effectively enhancing the overall integrity of the building.

III. Key Points for Connection Construction
Taking the connection between a prefabricated lintel and a wall as an example, construction must strictly adhere to standards such as the "Code for Acceptance of Construction Quality of Masonry Structures" (GB50203). Key processes include:

1. On-site Inspection: Check dimensional deviations of components (e.g., length ±5mm, width ±3mm), positions of embedded parts, and concrete strength (not less than 80% of the design grade).
2. Pre-treatment of Connection Areas: Clean dust from the wall surface. For masonry walls, construct up to the lintel bottom elevation in advance and reserve holes for reinforcing bar embedding.
3. Reinforcing Bar Embedding: Use HRB400 grade reinforcing bars. The hole diameter should be 4-6mm larger than the bar diameter, with a depth not less than 10d (d being the bar diameter). After injecting adhesive, embed the bars and cure for 24 hours.
4. Mortar Bedding: Lay 1:3 cement mortar on the lintel bottom surface with a thickness of 10-15mm, ensuring mortar fullness ≥80%.
5. Lifting and Positioning: Use a tower crane or manual hoist for lifting. Calibrate elevation and axis using a laser level, controlling deviations within ±3mm.
6. Sealing and Waterproofing: Seal the joint between the lintel and wall with polymer waterproof mortar and apply anti-rust paint to exposed metal parts.

Through standardized construction processes and quantitative parameter control, it can be ensured that prefabricated components for secondary structures work in coordination with the main structure, meeting building safety and functional requirements.