Determine the consistency of concrete by slump test where the nominal maximum size of the aggregates does not exceed 38mm
Test Appratus :
- Slump cone
- Tamping rod steel of 16mm diameter, 600mm long rounded at one end
- Fresh concrete
Slump test shall be conducted as per the procedure below:
- The internal surface of the mould shall be thoroughly cleaned and freed from superfluous moisture and any set concrete before commencing the test.
- The mould shall be placed on a smooth, horizontal, rigid and non-absorbent surface, such as a carefully levelled metal plate, the mould being firmly held in place while it is being filled.
- The mould shall be filled in four layers, each approximately one-quarter of the height of the mould. Each layer shall be tamped with twenty-five strokes of the rounded end of the tamping rod.
- The strokes shall be distributed in a uniform manner over the cross-section of the mould and for the second and subsequent layers shall penetrate into the underlying layer.
- The bottom layer shall be tamped throughout its depth. After the top layer has been rodded, the concrete shall be struck off level with a trowel or the tamping rod, so that the mould is exactly filled. Any mortar which may have leaked out between the mould and the base plate shall be cleaned away.
- The mould shall be removed from the concrete immediately by raising it slowly and carefully in a vertical direction. This allows the concrete to subside and the slump shall be measured immediately by determining the difference between the height of the mould and that ofthe highest point of the specimen being tested.
- The above operations shall be carried out at a place free from vibration or shock, and within a period of two minutes after sampling.
Read more Test:
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