Vibration is a mechanical process to achieve well compacted concrete. During compaction process, it is the main concern for supervisor or vibrator operator is to provide through vibration to concrete mix without segregation. In a well proportioned too or not too much vibration does not hamper the placing process of concrete. But in case of concrete having gap graded aggregate having large quantity of mortar than void in relatively large coarse aggregate i.e. not well proportioned or where due to reinforcement congestion or for any other unexpected condition high workability of concrete is required, over vibration results segregation.
This process produces accumulation of lighter constituents to the surface of concrete. The way how over vibration can be diagnosed are listed below:
a. Mortar comes out through the faulty joints in forms after application of vibration.
b. Coarse aggregate are found settled beneath finished surface.
c. Laitance on the surface.
d. Numerous air bubbles are appeared on the surface.
e. Foamy appearance of concrete.
An experience supervisor or vibrator operator can easily determine the over vibration with the above mentioned physical appearance of concrete.