MATERIALS, WORKMANSHIP, INSPECTION AND TESTING
Basic Terminology Of Workable Concrete
•A Concrete is said to be workable if it is easily transported, placed, compacted and Finished without any segregation.
•Workability is a property of mixed concrete, and a concrete is mixture of cement, aggregate, water & admixture.
•Due to this all the properties of concrete, whether in fresh state or hardened state, it is affected by these ingredients and their proportions.
•The most important nature of workable concrete is its lubricating nature.
•Advantages of more lubricating nature is
1) It will show little internal friction between particle and particle.
2) It will control the frictional resistance offered by the surface of the formwork and reinforced contain in the concrete.
3) It can be consolidated with minimum compacting effort.
•The factors which is help concrete to have more lubricating effect to reduce internal friction for easy compaction is
1) Water Content
2) Aggregate/Cement Ratio
3) Size Of Aggregate
4) Shape Of Aggregate
5) Grading Of Aggregate
6) Surface Texture Of Aggregate
7) Use Of Admixture
1)Water Content :-
Workability of concrete increases with increase in water content.
a) Increases quantity of water may cause bleeding in concrete.
b) Cement slurry also escapes through the joints of formwork
c) Strength of concrete may reduced.
2)Aggregate/Cement Ratio :-
Higher the Aggregate/Cement Ratio Poor Workability.
Lower Aggregate/Cement Ratio Give Better Workability.
3)Size Of Aggregate :-
Bigger size of aggregate give higher workability because a) less surface area b) Required less amount of water for wetting surface c) required less amount of paste for lubricating the surface.
4)Shape Of Aggregate :-
Workability of aggregate is also affected by shape of aggregates.( Angular, Flaky, Elongated, Rounded, Sub-rounded Cubical Etc.)
a) Angular, Flaky & Elongated Aggregate reduces the workability of concrete.
b) Rounded & Sub-rounded Aggregates high workability compare to other.
5)Grading Of Aggregate :-
Grading of aggregate have maximum influence on workability. The better is grading, the less amount of void in it. When total voids are less, excess paste is available to give better lubricating effect.
6)Surface Texture Of Aggregate :-
Porous and non-saturated aggregate will require more water than a non absorbent aggregate.
7)Use Of Admixtures :-
This is one of the commonly used method to enhance workability of concrete.(Plasticizer, super plasticizer, Pozzolanic materials improve more workability)
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Author & Editor Of This Blog.
Founder Of “KPSTRUCTURES”