Concrete Slump Test Demonstration

Concrete slump test is one of the must have testing especially for the fresh concrete. Every batch of newly mixed concrete produced at the plant shall be tested before it is recommended for concreting. One of the most watchful properties of concrete slump testing is the workability. The test of concrete slump would be perform either during the preparation of concrete trial batches or as the quality control check during the construction period of any structures.

Workability is the relative ease or difficulty of placing and consolidating concrete. The good workable mix will produce concrete, which allow it can be well compacted, transported and replaced without segregation. The workability of the fresh concrete mix are often used as an indirect check on the water content and therefore on the water/cement ratio of concrete. Thus, the success in concrete slump test is pretty much depends on the water-cement ratio in the mixture.

The technical standards used upon slump test for concrete in concreting works are as follows:

  • BS 1881: Part 2: 1983
  • C143-90a of ASTM

Equipment used in concrete slump testing is pretty much simpler compare to other type of equipment. The concrete slump test apparatus which are commonly used as follows:

  • Mould consisting of the frustum of a metal cone.
  • Standard 16mm diameter and 600mm long steel (galvanized) rod.
  • Rigid metal sheet (square shape).
  • Measuring scale (tape in m unit).

Performing the concrete slump test should be done every time the newly mixed of fresh concrete produced. The testing of slump can be performed at the batching plant or at the concreting site. It can be done by one person as the method of test can be followed easily. The easy to follow and perform of concrete slump test procedures are as stated below:

  • Place the cone on the rigid metal sheet which is on top of smooth and flat surface area.
  • Fill the mould with 3 layers of concrete approximately of the same thickness each.
  • Compact each layer of concrete mix by tamping it 25 times with the galvanized steel rod.
  • Level the top surface of the fresh concrete with the trowel – removal of excess concrete.
  • Lift the slump cone slowly in vertically position and by allowing the fresh concrete to subside.
  • Measure the difference in level between the subsided concrete. This difference in height measured in mm unit is taken as slump of concrete in fresh state.

There are 3 types of slump that might occur during the concrete slump testing and that is:

  • True Slump – It can be used for concrete structure project. The slump would be between 15mm to 150mm for an excellent quality.
  • Shear Slump – This type of slump cannot be used for construction. It is considered as Failed and repeating the concrete slump test is recommended.
  • Collapse Slump – Same goes to this type of slump; cannot be use for construction. Repeating the test is necessary or not, and noted as total failure in fresh concrete mixed.

The effectiveness of concrete slump testing would satisfy the below statement:

  • Suitable for detecting the changes in workability of rich concrete.
  • The difficulty in detecting the changes in dry concrete would be minimal.
  • Suitable for detecting the materials proportion from time to time while at the construction site.

The concrete in fresh state would be tested as to achieve the desired workability. Therefore, the concrete slump test should be perform upon the newly mixed concrete in order ensure the concrete mix satisfies that specification of works.

PolySteel Concrete Slump Test Demonstration Video

30th August 2011