WORKABILITY OF CONCRETE AND ITS TYPES
Workability is the property of concrete that determines the amount of useful internal work, necessary to produce full compaction i.e., it is the amount of energy needed to overcome friction while compacting concrete. Also defined as the relative ease with which concrete can be mixed, transported, molded, and compacted without any segregation. Workability is an important property of concrete and linked with compaction as well as the strength of the concrete. The desired workability for different grades of concrete is not the same.
Greater workability is preferred for a thin inaccessible section or heavily reinforced section rather than for mass concreting. Hence, we cannot set standard workability for different concrete casting works. Compaction and workability are somehow related to each other. Workability is also defined as the amount of useful internal work necessary to produce full compaction of concrete.
Types of Workability of Concrete
Workability of concrete can be classified into following three types:
- Unworkable Concrete: An unworkable concrete also known as harsh concrete, is a concrete with a very little amount of water. The hand mixing of such concrete is difficult. Such type of concrete has high segregation of aggregates. and it is very difficult to maintain the homogeneity of concrete mix.
- Medium Workable concrete: Medium workable concrete 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.
- Highly Workable Concrete: This type of concrete is very easy to mix, transport, place and compact. It is used where effective compaction of concrete is not possible. The problem is that there are high chances of segregation and loss of homogeneity in highly workable concrete.
Methods of Improving Workability of Concrete
- Increasing water/cement ratio
- Using larger aggregate
- By using well-rounded and smooth aggregate instead of irregular shape
- Increasing the mixing time and mixing temperature
- By using non-porous and saturated aggregate
- With the addition of air-entraining admixtures
- Adding appropriate admixtures in concrete
