Compaction ( Vibrating Table )

After concrete placement, must be eliminated or reduce unwanted air bubbles by compaction until the maximum density achieved in concrete. The amount of entrapped air depends on the efficiency of the concrete. Concrete with low efficiency, more air is trapped for this reason, for concrete with a low slump, there is a need for greater density. Air bubbles reduces concrete strength, increased permeability and decreased the strength of the bond between the steel rod and concrete.

The concrete density can be used two ways.

1. Manual density
2. The mechanical density

The most effective method of concrete density with medium performance (slump classes S2, S3) is using vibrator, because very stiff concrete are sensitive to pressure and sleazy concretes are sensitive to shake. Vibration function cause to reduce friction between the rock particles to become close to each other, and then air bubbles reach the surface. At the beginning of compaction, coarse aggregate is take away from the vibrator, because coarse aggregate mass is more than of fine aggregates. After collision the coarse aggregates, mortars started to flow between the aggregate.