Consistence tolerance - slump test

Consistence, measured using the slump test (BS EN 12350-2), is either specified as a class or target. Although a supplier will endeavour to provide the required value or range, deviations in production and sampling apply. The following tables give the maximum allowable deviation based on a spot sample taken from the initial discharge of a ready-mixed concrete truck.

For a slump class S2 or S3 you could expect a measured slump (spot sample from initial discharge) to fall within the range of 30 - 120mm and 80 - 180mm respectively, whereas for target slumps of 80mm and 120mm, the ranges will be 40 - 130mm and 70 - 180mm respectively.

Class Slump range

Max. allowable deviation on range limit (mm)

S1 10 - 40 -10, +30

S2 50 - 90 -20, +30

S3 100 - 150 -20, +30

S4 160 - 210 -20, +30

Target slump (mm)

Max. allowable deviation on target value (mm)

<40 -30, +40

50 - 90 -40, +50

> 100 -50, +60

Acknowledgement: The Concrete Society

The information contained in this nugget has been provided by The Concrete Society technical staff.

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4/6/2011http://www.concrete.org.uk/services/print_fingertips.asp?docid=800