Bleeding & Segregation in Concrete | Types-Causes-Prevention

Bleeding and Segregation in Concrete | Types, Causes & Prevention

Segregation and Bleeding of Concrete
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Bleeding and Segregation both are the types of most common error in freshly placed concrete.

In case if you forget, Fresh concrete means the wet mixture of concrete that can be moulded in various shape.

Sometimes it is known as Green Concrete. [Learn more about 'Green Concrete']

Okay, Back to the topic!

We all know that concrete is a mix of Cement, Aggregates, water. 

And the character of ideal concrete is where all the components of concrete are properly distributed and categorized.

That's the issue we face in Segregation and Bleeding of concrete.

Segregation and bleeding can be defined as the problem of fresh concrete in which concrete compounds separate from each other.

But there is a slight difference between them.

~ Know more about: Properties of concrete

➠ After completion of this article, You will be able to answer about :

1. What are Segregation and Bleeding in concrete?
2. Types of Segregation.
3. Causes.
4. How to prevent this?

Now let's start from the basic so that you won't have any doubt on this topic.

What is Segregation of concrete?

A good example of fresh concrete is a type of concrete in which all the compounds are properly distributed to make the concrete a homogenous mixture.

Segregation of concrete can be described as the separation of concrete materials.

Let's take an example, If a concrete sample shows a tendency of separation for a say cement paste from the rest of the ingredients- Then we may consider the concrete sample showing a tendency of Segregation.

This type of concrete shows all the undesirable features in the hardened concrete.

As the specific gravity of different ingredients of concrete is different, it is more common that the materials show a tendency to fall apart.

[ Eg: specific gravity of coarse aggregate is much higher than cement. ]

Types of Segregation

Depending upon "which materials (eg. cement paste, water, aggregates) separates from rest of the concrete", Segregation can be divided into three parts.

1. In the first type, the coarse aggregates separate or settle down from the rest of the ingredient of concrete.
2. Secondly, The cement paste separating away from the coarse aggregate.
3. And lastly, Some amount of water isolating from the entire concrete paste being a material of the lowest specific gravity.

Bleeding of concrete

BLEEDING OF CONCRETE

In simple words, bleeding of concrete is a form of Segregation in which water from concrete comes out to the surface.

It is also referred to the 'Water gain'.

One thing I will make you clear about that bleeding and segregation both are different in some aspects.

First of all, segregation is a common error for only freshly placed concrete whereas Bleeding is a type of segregation.

Secondly, Segregation is the separation of constituent materials from each other-it could be the separation of coarse aggregate, cement-paste or even water.

But for Bleeding of concrete, it is only water that pushed upwards due to the coarse aggregate and cement.

Water being the lowest specific gravity of water comes towards the surface of freshly placed concrete.

In general, Bleeding can be two types of -

1.  Normal Bleeding- Where water comes uniformly towards the entire surface of the concrete.
2. Channel Bleeding- Here seepage of water follows a particular path.

You must remember that water will not only rise towards the surface but sometimes water may also get trapped under the Coarse aggregates.

Channel bleeding is more harmful than the normal one, as this weakens the bond b/w cement paste and aggregate.

➠ Causes of Segregation and bleeding :

• Uses of High water-cement ratio in concrete.
• Overuse of vibrator helps heavier particle (such as Aggregates) to settle down, which means concrete loses its homogeneity.
• Poor selection of grade of aggregate.
• Inappropriate mixing of concrete ingredients.

How to prevent Bleeding and segregation of concrete-

CONCRETE ERROR DUE TO 'SEGREGATION OF CONCRETE'

1. Uses of Finer cement.
2. uses of Air-entraining admixtures.
3. Minimum water-cement ratio while taking care of other design parameters.
4. Application of more Fine aggregates.
5. Using other supplementary cementitious materials (eg.Fly-ash).
6. Proper design mix.
7. Increasing the amount of cement.

I hope you liked this article. Comment below if you have any question.

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