Segregation in concrete means separation of concrete ingredients as concrete mix is not homogeneous.A good picture of cohesion of the concrete mix is obtained by flow test. If the concrete is not cohesive the larger particles of aggregate will separate out and will move towards the edge. Another form of segregation happen if concrete mix carried out on a sloppy surface. A cement particle tends to run away from the center of the concrete mix and leaving the coarser material behind. Segregation cannot be measured in qualitative terms but can be detected by an expert eye.
A segregated concrete is a concrete of a variable strength and is relatively prone to cracking and leakages from the concrete. Therefore, it is very important to avoid segregation in concrete to make your structure long lasting.
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Here are some tips that are useful to avoid or reduce segregation. They are as follows:
01. The concrete mix should be properly designed with optimum quantity of water i.e. not too wet nor too dry.
02. Make sure the concrete is properly mixed at the correct speed in a transit mixture for at least two minutes. Regularly check the performance of mixer with respect to adequate uniformity of distribution of constituents in each batch.
03. Transport the concrete mix correctly. Choose the shortest route for transportation of concrete mix.
04. Place the concrete in its final position as soon as possible. Never place a concrete fromlarge heights.
05. Formwork should be water tight so that paste should leakage from the forms. Do not vibrate formwork.
06. Do not allow concrete to flow.
07. Use the vibrator correctly and never use the vibrator to spread a heap of concrete over a large area.
08. Vibrate the concrete for just the right time-not too long, not too less.
09. Use chemical admixtures such as air entraining agent in the mix. Entrained air reduces the danger of segregation.
10. If any segregation is observed in concrete, remixing should be done so to make it homogeneous again.