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High workability concrete

A concrete that can be readily compacted is termed ´workable´. However, to refer to a concrete as ´workable´ does not adequately describe its ease of placement or resistance to segregation. Workability depends on the means of compaction i.e. a concrete may be workable when using poker vibrator, but less so for hand ramming.

Workability can therefore be defined as the amount of internal work needed to fully compact fresh concrete. High workability concrete requires little compactive effort, yet does not segregate. High workability can be achieved in many ways but in general it will require the use of a plasticising admixture.

The measurement of workability, now referred to as consistence in Standards, is undertaken using consistence tests such as slump, flow or slump-flow tests.

Acknowledgement: The Concrete Society

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TR18 A guide to the selection of admixtures for concrete