This video visually explains the Effect of the Vibrator Used in Concrete.

Vibrating is a critical step on many concrete construction projects. When concrete is poured, it might have hundreds or even thousands of air bubbles, which can substantially weaken the concrete structure. Concrete vibrators eliminate air bubbles by vigorously shaking the freshly poured concrete.

Most concrete is under-vibrated or improperly vibrated. The best technique with an internal vibrator is to withdraw the vibrator very slowly, at a rate of around 1 inch per second. As long as bubbles still emerge as the concrete vibrator is withdrawn, more vibration is necessary.

Verify that the specific areas of concrete have not been vibrated already by other co-workers before proceeding with vibration. Submerge the vibrator head fully into the concrete, and hold it there for at least 10 seconds. Don't turn on the vibrator until the tip is fully submerged.

Pull up the vibrator at an average rate of no more than 3 inches per second; often, 1 inch per second yields the best results. Overlap the previous radius of vibration every time you insert the vibrator. A good rule of thumb is that the radius of action is four times the vibrator tip diameter. Stop vibration when air no longer escapes from the concrete and/or the concrete surface develops a sheen.