Concrete Slump Calculator
Determine workability and consistency class
Understanding Concrete Slump
The slump test is the most common method used to measure the consistency and workability of fresh concrete before it sets. It determines the flow of concrete and its ability to be handled, transported, and placed without segregation.
How to Measure Slump
To perform the test, a metal cone (usually 300mm tall) is placed on a flat, non-absorbent surface. It is filled with fresh concrete in three layers, each rodded 25 times. The cone is then carefully lifted vertically, allowing the concrete to subside. The difference between the height of the cone and the height of the collapsed concrete is the slump.
Slump Classifications
Different construction projects require different slump values. Here is a general guide based on standard measurements (in millimeters):
- S1 (10-40mm): Dry/Stiff. Used for foundations with heavy reinforcement or road construction.
- S2 (50-90mm): Medium/Plastic. The most common class for general reinforced concrete work.
- S3 (100-150mm): Wet/Flowable. Used for normal workability where easy placing is required.
- S4 (160-210mm): Very Wet. Used for sections with congested reinforcement or narrow spaces.
- S5 (>220mm): Self-Compacting. Flows under its own weight, requiring little to no vibration.