A mixing system comprising: a mixing drum having an inner drum wall and at least one mixing blade mounted on said inner drum wall, said mixing drum containing components for making a hydratable cementitious material; a hydraulic pressure drive operative to rotate said mixing drum at constant speed S C1 in the range of 1-25 revolutions per minute; a sensor operative to provide a sequence of values over time corresponding to the energy required to rotate the mixing drum; a computer processing unit for monitoring values provided by the hydraulic pressure sensor corresponding to the amount of hydraulic pressure required by the hydraulic drive; a data memory storage location for storing a first set of data corresponding to first sequence of values over time corresponding to the energy required to rotate the mixing drum containing a first hydratable cementitious material, said first sequence of values being monitored at a frequency of at least 10 times constant speed S C1; said computer processing unit being further operative for receiving a second sequence of values over time corresponding to the energy required to rotate the mixing drum containing a second hydratable cementitious material, said second sequence of values being monitored at a frequency of at least 10 times constant speed S C1; said computer processing unit being further operative for comparing said second sequence of values with said first sequence of values as a waveform, or as converted waveform data, and adjusting rheology or other property of said second hydratable cementitious material by introducing a liquid or other cementitious material component into said mixing drum based on said comparison. a mixing drum having an inner drum wall and at least one mixing blade mounted on said inner drum wall, said mixing drum containing components for making a hydratable cementitious material; a hydraulic pressure drive operative to rotate said mixing drum at constant speed S C1 in the range of 1-25 revolutions per minute; a sensor operative to provide a sequence of values over time corresponding to the energy required to rotate the mixing drum; a computer processing unit for monitoring values provided by the hydraulic pressure sensor corresponding to the amount of hydraulic pressure required by the hydraulic drive; a data memory storage location for storing a first set of data corresponding to first sequence of values over time corresponding to the energy required to rotate the mixing drum containing a first hydratable cementitious material, said first sequence of values being monitored at a frequency of at least 10 times constant speed S C1; said computer processing unit being further operative for receiving a second sequence of values over time corresponding to the energy required to rotate the mixing drum containing a second hydratable cementitious material, said second sequence of values being monitored at a frequency of at least 10 times constant speed S C1; said computer processing unit being further operative for comparing said second sequence of values with said first sequence of values as a waveform, or as converted waveform data, and adjusting rheology or other property of said second hydratable cementitious material by introducing a liquid or other cementitious material component into said mixing drum based on said comparison.