Disclosed are method and system for treating concrete in mixing drums of delivery vehicles having automated rheology (e.g., slump) monitoring systems programmed to dose fluids into concrete based on the monitored rheology. The present invention takes into account a Revolution-To-Discharge value (“RTD”) which reflects drum rotations needed to move concrete towards and through the mixing drum opening from which concrete is discharged, and also takes into consideration a Volume-Per-Revolution-Upon-Discharge (“VPRUD”) value which reflects the relation between the rate of discharge and rheology (e.g., slump) of concrete upon discharge. The invention is especially useful for reclaiming concrete in the drum after delivery and can confirm rheology based upon peak (maximum) discharge pressure. The present inventors found surprisingly that discharge pressure readings are useful for recalibrating automated rheology monitoring systems as well as for reporting and/or treating the remainder concrete.