The Slump Cone has Little to Do with Vibration

When the research began into controlling vibration frequency issues that plagued the surfaces of concrete structures, we correlated matching vibration energy to concrete workability that was measured in inches of slump. In examining several controlled vibrators frequency at pre-construction, we could not map a progression from the Static Yield Stress (SYS) value to the results in controlling forced water bleeding from varied fixed frequencies.

Thanks to the initial research by Iowa State University and the follow-up research into vibrator frequency transfers by Oklahoma State University it is evident that a static measure is inaccurate. With the addition of water reducing agents to pavement, bridge, or any pumpable mixtures, the more accurate measure of concrete workability is in reading the Dynamic Yield Stress (DYS) value. The DYS is not proportionately tied to the SYS of slump for plastic concrete that is subject to mechanical energy.

The DYS is the value that is necessary to initiate and maintain concrete flow where consolidation occurs. The more workable the concrete is made by WRAs the less you need the shear stress rate to reach concrete flow. The more you go over the DYS value with vibrator frequency, the more you separate material.

That Bingham was a smart guy.