8.5 : 浇筑混凝土

Concrete should be placed close to its final position in uniform horizontal layers.

After laying, the concrete layer is fully compacted to expel the entrapped air, and the next layer is laid above it while still in a plastic state to form a monolithic structure.

For horizontal or sloping surfaces, concrete is placed vertically against the existing layer. Forms are filled at a minimum rate of 6 feet per hour for a consistent finish on vertical surfaces.

Traditionally, concrete is placed using a chute, buggy, pipe, or conveyor belt.

Specialized methods, such as tremie concreting, use a smooth, vertical pipe with water-tight joints to place highly workable concrete in deep forms or underwater.

The concrete within the pipe flows under gravity as it is gradually lifted, ensuring its end stays submerged in concrete, preventing water intrusion.

Another specialized method for continuously placing and compacting low-workable concrete is the slip-forming technique, using forms that can be advanced horizontally or vertically at a steady rate once the concrete poured has been set.