Workability of concrete test

Workability of concrete

Workablity of concrete is the property of freshly mixed concrete which determines the ease and homogeneity with which it cab be easily mixed,placed,consolidated and finished.

We knew that what is concrete, it is a mixture of fine aggregate , course aggregate ,cement and water.
When these proportions are mixed it forms concrete, this concrete should in such a way that it should easily make any shape and spread without loosing water in it.

The workablity of concrete depends on many factors like, Cement content Water content , Mix proportions,Size of aggregates, Grading of aggregates etc. Workability is directly proportion to water cement ratio, water to cement ratio is inversely proportion strength of concrete, that means higher the water cement ratio lesser the strength of concrete, lesser the water cement ration higher the strength in concrete.

Types of Workability of concrete: 

Workability of concrete can be divided into following three types ;

1.  Unworkable Concrete

2.   Medium Workable

3.   Highly Workable Concrete

1.  Unworkable Concrete - Harsh Concrete:

An unworkable concrete can also be called as harsh concrete. It is a concrete with very little amount of water.The hand mixing of such concrete is not easy.

Such type of concrete has high segregation of aggregates as cement paste is not lubricated properly to stick to the aggregates.It is very difficult to maintain the homogeneity of concrete mix and compaction of concrete requires much effort. Water cement ratio of such concrete is below 0.4

2. Medium Workable Concrete:

This type of concrete workability is used in most of the construction works.This concrete is relatively easy to mix,transport,place and compact without much segregation and loss of homogeneity.

This type of concrete workability is generally used in all concrete construction with light reinforcement.Water cement ratio for medium concrete is 0.4 to 0.55

3. Highly Workable Concrete:

A highly workable concrete is very easy to mix, transport,place and compact in structures. Such concrete is used where effective compaction of concrete is not possible or in mass concrete. Such concrete flow easily and settle down without much effort. But there is high chances of segregation and loss of homogeneity in this case.

The coarse aggregates tend to settle at the bottom and the concrete past comes up.Such concrete is used in case of heavy reinforcement is used where vibration of concrete is not possible.
Example of highly workable concrete is self - compacting concrete. Water cemnt ratio of such concrete is more than 0.55.

|The concrete slump test measures the consistency of fresh concrete before it sets. It is performed to check the workablity of freshly made concrete,and therefore the ease with which concrete, and flows.It can also be used as an indicator of an improperly mixed batch.

Tests for Workability of Concrete:

Workabity of concrete mixture is mesured by:

a) Vee-bee consistometer test

b) Compaction factor test

c) Slump test