Effect of good compaction of concrete.ppt

Concrete compaction methodology, How to use vibrator in concrete.

9. In general, it is imperative to vibrate the concrete before it has set.
The vibration technique must be adapted to the structure and the type of
concrete.
The rules of good practice mainly concern the vibration time and the
position of the vibrators.
 The vibration time depends on the characteristics of the concrete (grain
size, consistency), the volume to be vibrated, the type of vibrator and its
power.
Precautions for using a vibrating needle :
         ·Concrete and vibrate in successive layers of 35 cm to 60 cm and in any
case to a thickness less than the length of the vibrating needle used.
        ·Quickly plunge the needle vertically into the concrete (if it is immersed
slowly, the concrete at the top will be compacted, which will prevent the
bubbles from rising from the mass concrete).
        ·Insert the needle about 10 cm into the previous layer, to bind the two
layers.
        ·Vibrate only for as long as is strictly necessary for tightening, otherwise
there is a risk of segregation.