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Segregation means separation of designed fresh concrete ingredients from each other resulting in the non-uniform mix. More specifically, this implies the separation of coarse aggregates from the mortar because of differences in size, density, shape and other properties of ingredients in which they are composed. Because of segregation honey comb is created in the concrete and it basically affects the strength of the concrete and its porosity.
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During concrete work, segregation in concrete can occur on site and it affects the durability of your structures. If you are constructing your own house, you have to understand about segregation in concrete.
In good concrete all the ingredients are properly distributed and make a homogeneous mixture. If a concrete sample exhibits a tendency for separation of coarse aggregates from the rest of the ingredients, it indicates segregation in concrete.
Depending upon the dryness or wetness of the concrete mix, there may be two types of segregation.
01. The coarser and the heavier particles tend to separate out or setting down from the rest of the matrix because they tend to travel faster along a slope or settle more than finer materials. This type of segregation may occur if the concrete mix is too dry.
02. Grout (water+cement) separating out from the rest of the material because of lowest specific gravity. This type of segregation may occur if the concrete mix is too wet. i.e. there is excess water. i.e. water-cement ratio is more.
A well designed concrete does not segregate if rightly mixed and batched. The causes of segregation are:
01. The difference in the specific gravity of the mix constituents i.e. fine aggregates and coarse aggregates.
02. The difference in the size of aggregate
03. Improper grading of aggregates.
04. Improper handling of aggregates.
05. Bad practices in handling and transporting of concrete.
06. Too much vibration of concrete.
07. Concrete that is not proportioned properly and not mixed adequately or too workable a mix.
08. Placing of concrete from a greater height.
09. Concrete is discharged from a badly designed mixer or from a mixture with worn out blades.