Concrete slump test

The slump test is used to ensure uniformity for different loads of concrete under field conditions.

The mould is carefully lifted vertically upwards, so as not to disturb the concrete cone.

If a shear or collapse slump is achieved, a fresh sample should be taken and the test repeated.

[1][3] Very dry mixes having slump 0 – 25 mm are typically used in constructing pavements or roads, low workability mixes having slump 10 – 40 mm are typically used for foundations with light reinforcement, medium workability mixes with slump 50 – 90 mm, are typically used for normal reinforced concrete placed with vibration, high workability concrete with slump > 100 mm is typically used where reinforcing has tight spacing, and/or the concrete has to flow a great distance.

It states in the procedure that when the cone is removed, it should be lifted up vertically, without any rotational movement at all.

[9] Other tests evaluating consistency are the British compacting factor test,[10] the Vebe consistometer for roller-compacted concrete (ASTM C1170),[11] Another way of determining slump is to use an automated slump meter.

Some automated slump meters can add water to the concrete mix in the delivery truck while in transit.

[12] In 2013 ASTM C94/C94M was revised to allow water additions during transit for trucks equipped with automated slump monitoring and measurement systems.