What is the flow table test?
The flow (Dutch: schudmaat) is a measure of the consistence (workability) of fresh concrete. It is determined with the flow table test according to EN 12350-5. The concrete is placed in a conical mould on a flat table. After the mould is lifted, the table top is raised to a fixed height and dropped fifteen times. This makes the concrete spread out. The average diameter of the spread concrete, in millimetres, is the flow value. It is sometimes also called the spread.
The cone for this test is different from the one used for the slump test: it is 200 mm high, with an internal diameter of 200 mm at the bottom and 130 mm at the top.
Flow or slump?
- The slump test measures how far a cone of concrete sinks. This test suits stiffer, “ordinary” concrete.
- The flow table test measures how far the concrete spreads. This test is more suitable for soft and fluid concrete, where the slump test makes less distinction.
- For self-compacting concrete, yet another test is used (the slump-flow, without dropping the table).
Application
The concrete standard EN 206 defines flow classes F1 to F6 (F for flow). The higher the number, the more fluid the concrete:
| Class | Flow diameter (mm) |
|---|---|
| F1 | ≤ 340 |
| F2 | 350 – 410 |
| F3 | 420 – 480 |
| F4 | 490 – 550 |
| F5 | 560 – 620 |
| F6 | ≥ 630 |
Practical tips:
- Order by consistence class: state the required class when ordering ready-mixed concrete. The plant will adjust the mix accordingly.
- Do not add water on site: extra water does make the concrete more fluid, but it raises the water/cement ratio and reduces strength and durability.
- Match the class to the job: densely reinforced structures and pumped concrete need a softer mix than, for example, a simple foundation that is well vibrated.
- Have it measured if in doubt: on larger jobs the flow is checked when the truck arrives.
Related Terms
- Consistence class
- Consistence range
- Fresh concrete
- Reinforced concrete
- Curing concrete
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