Bingham Fluids

While a flow of cement powder may not seem like a real fluid, it does share several fluid characteristics, one of which is behaving like a Bingham Fluid.

Bingham Fluids typically resist motion after being stored for a period of time, taking on gel-like properties (e.g. ketchup ).  Depending on the fluid, the storage period can range from milli-seconds to weeks.  Once these fluids start to flow, their thick/gel-like property can rapidly disappear and they will flow like water, sometimes faster.  For cement, this initial movement is short, estimated to be 25-100 microns occurring in a brief 25 to 250 milliseconds.  The energy required to achieve this initial movement (or shear) is referred to as the 'Bingham Energy Gap', which is characteristic that is typical of fine powders.

 When PMT is applied to cement silos equipped with air slides, it provides complex and/or multiple frequency pulses into the air flow generate micro-shear at the airslide/powder interface to bridge the ‘Bingham Energy Gap’.

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