Pouring Requirements for Prefabricated Slab Houses
The pouring requirements for prefabricated slab houses must be strictly controlled from four aspects: slab joint treatment, installation and connection, composite layer construction, and quality control, as detailed below:
I. Slab Joint Filling Requirements
Slab joint treatment is a core aspect of pouring, directly affecting the structural integrity. First, thoroughly clean the debris, dust, and loose particles from the slab joints, and moisten them with water 24 hours in advance to ensure strong adhesion between the concrete and the prefabricated slabs. The filling material should be fine aggregate concrete with a particle size ≤15mm and a strength grade not lower than C20. If the joint width exceeds 40mm, reinforcement should be installed according to design requirements (typically φ6-φ8@200-300mm) to enhance crack resistance. Pouring should be done in two stages: first, fill to 10-20mm below the slab surface, then fill flat after initial setting, and reserve a 5mm deep groove on the top surface to prevent hollowing of the subsequent leveling layer. After filling, cover and maintain moisture for at least 7 days, and proceed to the next process only after the strength reaches C15 or above.
II. Installation and Connection Requirements for Prefabricated Slabs
During installation, strictly control the gap and bonding quality. A 20-40mm expansion joint should be reserved between two prefabricated slabs, and the bottom end of the slab should be treated with 1:2 cement mortar, with a thickness controlled at 10-15mm to enhance friction. The holes at both ends of the wall prefabricated slabs must be filled solid with C20 concrete, and the use of bricks is strictly prohibited to prevent cracks caused by inconsistent material shrinkage. For roof prefabricated slabs, first lay a φ4@150mm bidirectional steel mesh, then pour 6-8mm thick crushed stone concrete to form a waterproof and anti-permeable layer.
III. Composite Slab Construction Requirements (Combination of Prefabricated and Cast-in-Place)
Composite slabs achieve overall load-bearing capacity through the collaborative work of the prefabricated layer and the cast-in-place layer. The standard thickness of the prefabricated PC slab is 60mm, using concrete with a strength grade above C30, and truss reinforcement is configured inside to improve flexural stiffness. The thickness of the cast-in-place layer should be ≥70mm. Before construction, bind a φ8@150mm bidirectional steel mesh and weld it firmly with the truss reinforcement of the prefabricated slab. The joint width should be controlled at ≤20mm, filled with high-strength special joint filling mortar, and the reinforcement of the cast-in-place layer should be continuously arranged across the joint to ensure a smooth load transfer path.
IV. Quality and Safety Considerations
Material and construction specifications are the foundation of safety assurance. Prefabricated slabs must be purchased from qualified and reputable manufacturers, with a concrete strength not lower than C30, and the specifications and quantity of reinforcement must comply with the design drawings. During construction, it is strictly prohibited to arbitrarily cut holes or slots in the prefabricated slabs. If pipeline embedding is required, the path should be planned in advance and mechanical cutting should be used. Before pouring, focus on checking the cleaning of slab joints, the anchorage length of reinforcement (≥35d), and the positioning error (<5mm) to ensure compliance with the Technical Specification for Prefabricated Concrete Structures JGJ1-2014 standard.
