Pouring The physical act of depositing wet, mixed concrete directly from a transit mixer truck, buggy, or wheelbarrow into the prepared formwork.
Pouring concrete is a time-sensitive step that requires a highly coordinated crew. The wet mix must be deposited evenly to avoid air pockets and segregation (separation of water and gravel). In NYC, the concrete must meet a minimum compressive strength of 3,000 to 4,000 PSI, and it must be placed continuously to avoid weak points known as "cold joints".
Frequently Asked Questions About Pouring
What happens during a concrete pour?
Wet concrete is deposited from the mixer truck, buggy or wheelbarrow into the prepared forms, then spread and consolidated evenly.
Why must a pour be continuous?
Interruptions create cold joints, weak planes where one batch has begun setting before the next is placed.
What is segregation?
Separation of the mix, where water and fines rise and coarse aggregate settles, usually from over-handling or dropping the concrete too far. It weakens the finished slab.
What strength is specified?
Sidewalk mixes are typically specified in the several-thousand PSI range depending on the DOT detail and use. Follow the approved specification for the project rather than a generic value.