Section 3: Concrete Slump Test Overview

Review of key concepts related to the Concrete Slump Test.

When the concrete contains aggregate larger than allowed for the slump test, the larger aggregate must be …..

Wet screened over 1- ½ inch sieve

The mold for making slump test is in the shape of …..

The frustrum of a cone

What is the height of the slump mold?

12 inches.

True or False: The interior surface of the slump mold is allowed to have minor irregularities.

False.

For use in the slump test, the tamping end or both ends of the tamping rod must be …..

The ends must be rounded to a hemispherical tip.

True or False: The slump mold should be dry before starting the test.

False

What type of surface should the slump mold be placed on?

Flat, level, damp, nonabsorbent, and rigid.

How many layers does the slump mold get filled with?

Three layers.

What is the volume of each layer when filling the slump mold?

Each layer should fill approximately one third the volume of the mold.

How many times should each layer be rodded?

25 times uniformly over the cross section.

How deep should the tamping rod penetrate into each layer?

Rod each layer to its depth, on the second and final layer, the rod should penetrate approximately 1 inch.

What must be done if the concrete drops below the top of the slump mold during rodding?

Add additional concrete to keep an excess above the top of the mold.

What must be done around the base of the mold before lifting it?

Concrete must be removed from the area surrounding the base of the mold.

True or False: The sides of the slump mold should be tapped after final rodding.

False.

True or False: The slump mold should not be rotated or twisted when being lifted.

True.

How much time is allowed for lifting the slump mold?

5 +- 2 seconds

Where is the measurement for slump made?

To the displaced center

What is the accuracy to which the slump of the concrete is measured and reported?

To the nearest ¼ inch.

How much time is allowed to conduct the slump test from start to finish?

Two and a half minutes.