Concrete slump test or slump cone test is to determine the workability or consistency of concrete mix prepared at the laboratory or the construction site during the progress of the work. Concrete slump test is carried out from batch to batch to check the uniform quality of concrete during construction.
The slump test is the most simple workability test for concrete, involves low cost and provides immediate results. Due to this fact, it has been widely used for workability tests since 1922.
The slump is carried out as per procedures mentioned in ASTM C143 in the United States,
IS: 1199 – 1959 in India and EN 12350-2 in Europe.
Generally concrete slump value is used to find the workability, which indicates water-cement ratio, but there are various factors including properties of materials, mixing methods, dosage, admixtures etc. also affect the concrete slump value.
Factors which influence the concrete slump test:
- Chemical admixtures dosage, type, combination, interaction, sequence of addition and its effectiveness,
- Air content of concrete,
- Concrete batching, mixing and transporting methods and equipment,
- Temperature of the concrete,
- Sampling of concrete, slump-testing technique and the condition of test equipment,
- The amount of free water in the concrete, and
- Time since mixing of concrete at the time of testing