Concrete formwork installation is a crucial process for ensuring structural quality and construction safety. Its construction must strictly adhere to the technical process of "support first, formwork second, alignment first, reinforcement third," and implement full-process quality control.
I. Construction Process and Installation Sequence
Formwork installation generally follows the principle of "vertical first, horizontal second." The specific process is: surveying and setting out → erecting the support system → assembling the formwork → correcting verticality and flatness → reinforcement and locking → acceptance.
1. Vertical Components (Columns, Walls): First, tie the reinforcing steel, then install the formwork around the perimeter, and finally correct and reinforce the verticality using diagonal braces and through-wall bolts. For continuous columns, install the formwork at both ends first, and then use a straight line to align the formwork in the middle column.
2. Horizontal Components (Beams, Slabs): First, erect a full-span support frame, install the bottom formwork of the beam, tie the beam reinforcing steel, and then install the side formwork of the beam and the floor slab formwork. For beams and slabs with a span ≥ 4m, the formwork should be cambered according to design requirements. The camber height should be 1/1000 to 3/1000 of the span to offset the downward deflection caused by the concrete's own weight.
II. Key Quality Control Points
1. Joint Treatment: Formwork joints must be tight and leak-proof. Wooden formwork should be moistened with water before pouring, but there should be no standing water. Sponge strips should be pasted at the joints or rigid joints should be used to ensure a smooth concrete surface without misalignment.
2. Support System: A base plate should be placed at the bottom of the support uprights. Direct support on uncompacted backfill is strictly prohibited. The spacing between uprights, the step distance of horizontal bars, and the installation of scissor braces must meet the requirements of the construction plan to ensure overall stability. The uprights of the upper and lower support layers should be aligned and base plates should be laid.
3. Verticality and Flatness: Strict regulations govern the allowable deviations for cast-in-place structure formwork installation, such as axial position deviation ≤ 5mm, floor height verticality deviation ≤ 6mm (when floor height ≤ 5m), and surface flatness deviation ≤ 5mm. During installation, plumb bobs, levels, and other tools must be used for repeated checks.
III. Safety Operating Procedures
1. Personal Protective Equipment: Workers must wear safety helmets. When working at heights (above 2m), safety belts must be worn, and non-slip shoes must be worn. Climbing or walking on the support system is strictly prohibited.
2. Edges and Openings: Guardrails must be installed at edges. Pre-reserved openings, elevator shafts, etc., must be covered with plates or protective netting to prevent falls.
3. Material Stacking: Formwork and connectors should be stacked neatly and categorized. They must not be piled together on the operating platform or scaffolding to prevent overloading. Throwing materials during formwork installation is strictly prohibited; personnel must be present at the top and bottom to catch them.
4. Process monitoring: During the concrete pouring process, a designated person should be assigned to observe the formwork and support system. If any abnormalities such as deformation or displacement are found, pouring should be stopped immediately and reinforcement measures should be taken.
