Workability of concrete is defined as that property of fresh concrete which determines the ease and homogeneity with which concrete can be mixed, placed, compacted and finished is lastly.
Workability of fresh concrete is a complex system which involves different parameters such as flowability, mobility, stability, pumpability, compactability and resistance to segregation bleeding.
Through workability of a fresh concrete is a complex system of two critical parameter:
- Consistency
- Homogeneity
1. Consistency of workability
Firstly consistency is the ability of a fresh mixed concrete to flow. Thus Slump cone test, compaction factor test is used for measuring consistency of concrete
2. Homogeneity
Means uniform and stable distribution of ingredients such as cement, aggregate and water and also provide resistance to segregation. Reduction in viscosity increases flow and improve the consistency is lastly.
Factor affecting of workability:
- Water content’
- Shape
- Size
- Texture
- Mix proportion
- Grading
- Use of admixture
- Time
- Temperature
1. Water content
The water content decrease with decrease in slump and hence to p[roduce durable concrete water used in concrete must be minimum. Higher the water content per m3 of concrete, higher will be fluidity of concrete, which affects workability is lastly.
2. Shape
Firstly rounded aggregate requires less cement paste and water content for given workability.
Rounded aggregate will give a more workable concrete. angular, elongated or flaky aggregate makes the concrete harsh is lastly.
3. Size of aggregate:
For larger size aggregate the surface area is less and hence less amount of water and cement paste is required to cover the surface area.
4. Surface texture of aggregate
Aggregates having rough surface texture will require more cement paste to cover them. Hence smooth textured aggregate gives more than rough textured aggregate
5. Mix proportion:
Firstly aggregate cement ratio is an important factor influencing its. Rich concrete with lower aggregate cement ratio more paste is available to mix cohesive and fatty to give better of its finally.
6. Grading of aggregate:
Firstly it is concrete is directly proportional to grading of the aggregate. Thus it increases if the aggregates are well graded.
7. Use of admixture in workability
Admixture such as air entraining agent, pozzolana cement and plasticizers increase the workability of concrete without affecting its strength adversely is lastly.
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