Placing and Working Concrete
Placing concrete in forms is much more complicated than just pouring the concrete into the form. If the concrete falls too great at height, the large gravel particles will separate from the fine particles when the concrete reaches the bottom. In order for concrete to dry strong, several conditions must be met after the concrete is placed. For one, the concrete needs to be consolidated. Consolidating is accomplished with the use of a concrete vibrator. A vibrator works out the air that is trapped in the concrete.
On concrete work where the end product will be flat, the concrete must first be leveled off with a screen board. This smooths and further consolidates the surface of the concrete. After the concrete has firmed up a little, it is then finished with a steel trowel. This leaves a smooth finish.
Care must be exercised while the concrete is curing. The concrete must not be allowed to free or cure too fast as this producing concrete that is weak and will not hold up to traffic (foot or otherwise) and various weather conditions. Reinforcement steel can also be a useful tool in placing concrete.
