Apparatus includes a signal processor or processing module configured to receive signaling containing information about a hydraulic pressure of a hydraulic fluid used or required to rotate a drum of a concrete truck having concrete contained therein; and provide corresponding signaling containing information about a slump alert of the concrete contained in the drum, based upon the signaling received. The signal processor or processing module determines the slump alert based upon a measurement of the hydraulic pressure of the hydraulic fluid used or required to rotate the drum at a specific rotation speed. The apparatus includes a memory having a look-up table containing information about reference slumps for corresponding reference concretes that are in-specification and out-of-specification based upon the hydraulic pressure measured. The signal processor or processing module may be configured to index the look-up table based upon the signaling.