Assembly Joints of Rural Prefabricated Houses

The assembly joints of rural prefabricated houses need to be comprehensively addressed from four aspects: material selection, treatment process, connection method, and effect issues, as detailed below:

Joint Material Selection

When assembling prefabricated panels, non-shrink epoxy structural assembly adhesive is preferred. If mortar or epoxy mortar is used, shrinkage can easily lead to cracks in the prefabricated panels, resulting in high remediation costs later. For example, in Henan, the joints of prefabricated houses are rigidly connected through secondary pouring of C40 concrete, with a 70-year lifespan commitment based on the standards of epoxy resin coating and concrete impermeability grade P8. However, due to the chloride ion corrosion rate in the Yellow River basin being 1.8 times faster than in the laboratory, additional attention to durability is required.

Joint Treatment Process

1. Crack Repair:
   • Use a wall planer to plane off the surface plaster by more than 10 centimeters, chisel out an inverted V-shaped groove, and clean the dust with a blower;
   • Apply repair adhesive for leveling, and use an angle grinder to polish uneven areas until flat;
   • Apply carbon fiber impregnating adhesive, paste carbon fiber cloth after applying the base coat, use a scraper to remove air bubbles in a unidirectional manner to avoid voids, and finally apply modified epoxy impregnating adhesive on the surface.
2. General Treatment:
   • Mix adhesive in a 2:1 ratio and apply it to the joints of structural components before positioning and assembling;
   • When treating gaps, fill and scrape the overflowing part flat, and allow it to stand for 12 hours after construction for curing.

Joint Connection Method

According to the 03SG435-1 Atlas of Prestressed Concrete Hollow Slabs, the connection between the end of the prefabricated panel and the transverse joint should follow the specifications, but the specific structure should be determined in combination with design requirements, such as enhancing integrity through steel bar anchoring or reserved slots.

Joint Treatment Effect and Issues

1. Effect:
   • Japanese seismic experiments show that due to the stress dispersion characteristics of modular buildings, the displacement in a magnitude 7 earthquake is 40% less than that of brick-and-mortar structures;
   • A detection of a 5-story experimental building in a factory in Kaifeng shows that the vertical bearing capacity reaches 12kN/㎡, meeting rural residential standards.
2. Issues:
   • Low-temperature environment shrinkage: Monitoring of a project in Northeast China in 2023 shows that the joint sealant shrinks by 0.3mm per year at -30℃, requiring the selection of low-temperature-resistant materials;
   • Temperature difference condensation: Farmers in Qixian reported condensation at the joints when the indoor-outdoor temperature difference was 15℃ in winter, but this can be effectively solved with electric heating adhesive strips provided by the manufacturer.

Conclusion: The joint treatment of rural prefabricated houses should take into account material performance, construction specifications, and environmental adaptability. Through scientific material selection, precise construction, and targeted remedial measures, the structural safety and durability can be significantly improved.