Patent ID: 8764272

Claim:
A method for monitoring thixotropy of concrete, comprising: (A) rotating a concrete mix, or the components of a concrete, in a concrete mixing drum at a first mixing speed (S 1 ) to mix completely the concrete mix components or otherwise to maintain the concrete in a completely mixed state; and (B) measuring the thixotropy of the concrete mix by monitoring the reversible, time dependent change in viscosity occurring after rotational speed of the concrete mix in the mixing drum is altered by changing to another speed (S 2 ) that is different from S 1 ,said concrete mix thixotropy measuring being accomplished by increasing the speed of the mixing drum to a faster constant mixing speed S 2 such that S 2 is at least one half revolution per minute faster than S 1 ; monitoring the energy required to rotate the mixing drum (E R ) at constant speed S 2 until after E R levels off over time; and storing in computer memory a first value corresponding to the maximum energy required to rotate the mixing drum (E R-MAX ). after increasing the mixing speed from S 1 to S 2 and also storing in computer memory a second value corresponding to the average energy required to rotate the mixing drum during a predetermined time period wherein the energy required to rotate continuously the mixing drum at constant speed S 2 begins to level off to a minimum level (E R-MIN ); (C) comparing said E R-MAX and E R-MIN values to at leas one set of predetermined target values stored in computer memory; and (D) adjusting yield stress, plastic viscosity, or thixotropy of said concrete mix contained in said rotating mixing drum using a liquid component,based on comparing said E R-MAX and E R-MIN values to at least one set of predetermined target values stored in computer memory.