What Is Workability of Concrete?
The term workability indicates the ease or difficulty with which the concrete is handled, transported and placed.
The amount of water present in concrete should be in the proper ratio. Generally, a higher water-cement ratio is required for good workability.
In the actual function of water is to lubricate the concrete. The concrete which is easy for handling and placing is a workable concrete.
There are various test to measure the workability of the concrete mixture. The test such as flow test, compacting test and slump cone test is done to determine the workability of the concrete mixture.
Factors Affecting The Workability of Concrete
- Water Content
- Size of Aggregate
- Shape of Aggregate
- Grading of Aggregate
- Surface Texture of Aggregate
If the water content is more, it will result in an increase in workability of concrete, If the water content is less than required, it will result in difficulty to handle the concrete and place it in the proper place. So water is added in the concrete according to water-cement ratio.
The ratio of the amount of water to the amount of cement by weight is termed the water-cement ratio. The strength and quality of concrete depend on this ratio.
The quantity of water is usually expressed in litre per bag of cement. if water required for one bag of cement is 30 litres, the water-cement ratio is equal to 30/50 = 0.6.
The water-cement ratio should be such that it should impart a reasonable degree of workability to concrete, excess water affects the durability and strength of the concrete.
Lesser water-cement ratio makes the concrete unworkable while the excess water-cement ratio is liable to segregation. keeping the quality and quantity of ingredients the same, it is the water-cement ratio that determines the strength of concrete.
Size of Aggregate
If the size of aggregate is small that means more is the surface area which required more water as well as more cement paste or vice versa. So the bigger size of aggregates for the given quantity of water and cement paste will give higher workability.
Shape of Aggregate
The workability of rounded or cubical size aggregate is more than angular or flaky aggregates. As angular or flaky aggregates give the concrete very harsh.
Due to the round size of aggregates, the frictional resistance between the aggregates is greatly reduced. So, as well as possible the aggregates should not be angular or flaky in the shape for getting more workable concrete.
Grading of Aggregate
If aggregates are well graded, that means less will be the void content and higher will be the workability, so as well as possible, the aggregate should be the well-graded.
Surface Texture of Aggregates
If the surface of the aggregates is smooth or glassy texture, it will produce less surface area and will give better workability.
The frictional resistance between the smooth particle is reduced and which will produce higher workability. So this is an important factor for workability.