What is V-funnel flow time?
V-funnel flow time is the time in seconds that fresh concrete takes to flow completely out of a standardised V-shaped funnel. It is a measure of the viscosity of the mix: the more viscous the concrete, the longer the flow time. The test is described in EN 12350-9 and is mainly used for self-compacting concrete (SCC), which fills formwork without vibration. In Dutch the result is called trechtertijd, “funnel time”.
How the test works
- The V-funnel is placed on a level base with the trapdoor at the bottom closed.
- The funnel is filled with fresh concrete in one go and struck off level.
- The trapdoor is opened and timing starts.
- Timing stops as soon as you can see down through the opening at the bottom. That is the flow time.
The test is not suitable when the maximum aggregate size exceeds 22.4 mm.
What the result tells you
- Short flow time: the concrete is very fluid and fills quickly, but the risk of segregation increases: coarse aggregate settles while water or fines rise.
- Long flow time: the concrete is viscous and stays homogeneous, but fills more slowly and may struggle to pass through congested reinforcement.
- Rising time on repeat: if the flow time increases after the concrete has stood in the funnel briefly, this can indicate blocking or segregation.
The concrete standard EN 206 includes viscosity classes for self-compacting concrete. The required class depends on the element, formwork shape and amount of reinforcement, and is specified by the structural engineer or concrete technologist.
In practice
For ordinary DIY concrete pours, flow time plays no role; what matters there is the consistence class you order from the ready-mix plant. Flow time is mainly a quality-control tool for ready-mix plants, precast factories and contractors working with self-compacting concrete.
Related terms
- Fresh concrete
- Consistency class
- Consistency range
- Flow table test
- Aggregates
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