Slump Test

In Site conditions, an engineer has different types of responsibility. Among them, an engineer has to ensure concrete strength properly. On the other hand, an Engineer has to ensure the workability of concrete for his worker. It is a balance between workability and strength. On-Site an engineer can easily balance this proportion by a simple test with some simple tools. Slump test is a test that can help an engineer to balance this workability as well as strength.

Slump Test:

A slump test is used to determine workability and it is a measure of the resistance of concrete to flow under its own weight. To check the workability of freshly mixed concrete slump tests is used on site. By doing this test engineer can maintain the water-cement ratio as well.

Apparatus Needed to Perform Slump test:

1.   Cone-shaped mold (On-base 8-inch dia, On top 4-inch dia and height of 12 inches)

2. A taming rod with 16mm Dia

3   3. Measuring tape

Procedure:

1. First of all, mark the cone. Divide the cone into three-part.

2. Fill the first part of cone with concrete and tamp the concrete 25 times with the tamping rod

3. Then fill the 2^nd part of the cone with concrete and tamp the concrete 25 times with tamping rod.

4. And lastly, fill the 3^rd part of the cone with concrete and tamp the concrete 25 times with the tamping rod again.

5. Now nicely complete the fill up the cone.

6. Now Pull the slump cone vertically upward and observe the change in concrete.

7. Measure the concrete length and get the result of the slump.

Types of Slump:

Image: Four types of Slumps

·        Four Types of slump are commonly Formed. Among them according to ASTM-C143 True slump is permissible. In true Slump concrete remains intact as well as retains a symmetric shape.

·        Zero Slump and Collapsed slump both out of range of Workability as well strength. According to ASTM C143 Specifically caution for ½” <test result and 9”> test result.

·        If test result form a shear collapse the test must be repeated with a different sample of concrete. A concrete that exhibits a shear slump in a second test is not sufficiently cohesive and should be rejected completely.

Measurement of Workability with slump:

Measurement	Denotation	Uses
0”-2”	Stiff	Massive Section with Little rebar
2”-5”	Medium	Column, Beams, Retaining walls
5”-7”	Fluid	Heavily reinforced sections, Flow able concrete

Resource: Engineering Materials By E.R Latifee