Segregation of Concrete !!!!!!

Segregation is the separation and cement paste and aggregate of concrete with each other during handling and placement. Segregation also happens due to over vibration of the concrete during compaction where cement paste comes to top of the concrete and aggregate settles at the bottom.

Segregation affects the strength and durability of the concrete. In a concrete all the aggregate is coated with cement paste and forms a homogeneous mix but due to the jerks and vibrations, aggregate gets separated from the cement paste. 

Causes of Segregation in concrete 

1. High water cement ratio. It generally happens at site due to concrete handled by unskilled labors.
2. Excessive vibration of the concrete causes aggregate to settle down while cement concrete remains at the top.
3. When concreting is done from height usually in underground foundations and rafts.

Precaution that should be applied to control segregation

1. The concrete should not be thrown from height during concreting. The vertical height should not be more than 1.5. If the height is more than 1.5 the concreting should be done by, providing inclined chutes.
2. The vibration should be done by skilled labor. Excessive vibration by needle mechanical vibrator should not be done.

Water cement ratio should be properly maintained during concreting. Low water content as well as high content in concrete results in segregation so water content should be properly checked during concrete batching.