How to Handle Steel Bars in Prefabricated Slab Houses

The treatment and reinforcement of steel bars in prefabricated slab houses should be selected based on specific circumstances, as detailed below:

Treatment of Exposed Steel Bars in Prefabricated Slabs

If steel bars are exposed on the prefabricated floor slab, first, cut the excess steel bars to ensure their length meets the requirements. Next, perform rust removal using tools such as wire brushes or sandpaper to remove rust from the surface of the steel bars, ensuring good adhesion with subsequent materials. Then, roughen the concrete at the location of the exposed steel bars, taking care to control the roughening depth to avoid damaging the internal structure of the prefabricated slab. After roughening, rinse the concrete surface with water to remove excess sand and gravel. Finally, perform patching. If the exposed steel bars are shallow, use a 1:2 cement mortar for patching; if the exposed steel bars are deep, first treat the interface and then fill and compact with fine aggregate concrete of a higher grade for patching.

Steel Bar Practices in Reinforcement of Prefabricated Slabs

• Section Enlargement Reinforcement Method: A reinforced concrete post-cast layer with a thickness of not less than 40mm can be added on the slab surface or slab bottom. For ease of construction, a composite layer is often cast on the slab surface. The post-cast reinforced concrete layer on the slab bottom should preferably be constructed using the spraying method. The structural reinforcement in the composite layer generally uses φ6@150–200. If a continuous slab is designed, φ8–10@150–200 steel bars should be arranged in the span direction of the slab and placed continuously. To enhance the bonding and interlocking capacity between the new and old concrete, the slab surface should be roughened, the dust blown off, and a layer of concrete interface bonding agent applied; the loose concrete in the slab joints should be chiseled out, connected with φ8@600 anchor bars, and then concrete poured.
• Fiber Fabric Reinforcement Method: Carbon fiber, glass fiber, or other fiber fabrics are pasted along the span direction of the slab on the tensile surface at the slab bottom, with reliable anchoring at the ends to improve the load-bearing capacity and crack resistance of the prefabricated slab.

Steel Bar Practices in Overall Reinforcement of Prefabricated Slab Houses

• Vertical Direction: Add external R.C. columns (240*300, with 4 steel bars of diameter 12 - 16 and stirrups of 6@200) at each span of the exterior walls to enhance the vertical stability of the house. Add columns appropriately on both sides of the gable walls, and consider setting beams in both directions at the corner column positions to form a frame structure, improving the overall rigidity of the house.
• Horizontal Direction: Set R.C. beams at both ends of the exterior walls, connected to the corner columns, to form horizontal constraints. In the middle spans, the steel bars can only be tensioned at the end, which can be tightened with bolts or clamped with steel plates from the plane and then welded, enhancing the horizontal deformation resistance of the house. Beams can also be set on the roof to further improve the overall integrity and stability of the house.