Requirements for Cement Prefabricated Reinforcement Houses

The following core requirements must be followed for the reinforcement of cement prefabricated houses:

I. Criteria for Reinforcement Assessment

According to the new regulations of the Ministry of Housing and Urban-Rural Development in 2026 and practical operational norms, the reinforcement of houses should be comprehensively assessed based on hazard levels and cost-effectiveness:

1. Grade C/D Dangerous Houses: Houses identified as Grade C (partially dangerous) or Grade D (overall dangerous) by a Class A institution, and in compliance with urban area planning, may apply for original demolition and reconstruction; Grade D houses must be forcibly evacuated and prioritized for reconstruction.
2. Economic Assessment for Grade C Houses: If the cost of reinforcement exceeds 50% of the reconstruction cost, an application for demolition and reconstruction can be made; otherwise, a professional reinforcement plan must be adopted.
3. Houses Below Grade B: Only routine maintenance is required, such as painting exterior walls, replacing pipelines, and waterproofing, as part of old building renovations.

II. Prerequisites for Reinforcement

A structural safety assessment report must be issued by a Class A institution. Developing a reinforcement plan without completing the assessment is a violation that may lead to structural safety hazards or resource waste. The assessment report serves as the legal basis for subsequent design, construction, and acceptance.

III. Reinforcement Methods and Technical Parameters

1. Carbon Fiber Sheet Reinforcement:

   • Suitable for scenarios where the flexural capacity of floors and beams is insufficient.
   • Carbon fiber sheets have a tensile strength of 4052.3 MPa and are pasted onto the tensioned surface of components without increasing the cross-sectional size or affecting the usable space.
   • The normal tensile bond strength of the accompanying impregnating adhesive must be ≥ 3.8 MPa (according to GB 50728) to ensure concrete cohesive failure rather than adhesive layer failure.

2. Steel Plate Bonding Reinforcement:

   • Addresses weak node connections, such as at the junction of panels and walls.
   • Steel plates are bonded with structural adhesive to achieve steel-concrete collaborative loading, with the shear strength of the bonding adhesive needing to be ≥ 22.5 MPa, significantly enhancing the overall integrity of the nodes.

3. Rebar Planting Reinforcement:

   • Used for adding new components (such as ring beams and structural columns) to enhance seismic performance.
   • The splitting tensile strength of the rebar planting adhesive must be ≥ 20.11 MPa to ensure effective connection between new and old concrete, preventing pull-out failure.

4. BFRM Basalt Fiber Tough Mortar:

   • Specifically designed for seismic reinforcement of masonry walls, with a single-sided plastering thickness of only 15-30 mm and a self-weight of 30-50 kg/㎡. It reaches design strength after 7 days of curing.
   • Compared to traditional 8 cm thick panel wall reinforcement, it reduces space occupation by 60%, making it suitable for scenarios with limited floor height or historical building preservation.

In practical applications, the combined solution of 'carbon fiber + steel plate bonding + rebar planting' is the most common, addressing issues such as insufficient load-bearing capacity, weak nodes, and poor overall seismic performance simultaneously, forming a three-dimensional reinforcement system.