A building material apparatus includes at least one building material transport part which follows a building material drum, wherein the building material transport part is designed to transport building material which is to be at least partially cured, and at least one part sensor. The part sensor is arranged on and/or in the building material transport part and is designed to detect at least one intensive variable, or at least one variable which corresponds at least to the intensive variable, of the building material in the building material transport part.

A system features a combination of an acoustic sensor and a communication transmitter. The acoustic sensor is arranged on a rotating container or drum having a slurry contained therein, including concrete, and configured to provide an acoustic signal to sense an acoustic signal containing information about a characteristic of the slurry, and provide acoustic sensor signaling containing information about the acoustic signal sensed. The communication transmitter is arranged on the rotating container or drum, and configured to receive the acoustic signal, and provide the acoustic signal received from the rotating container or drum for further processing.

A mixer and a method for the mixing of a cementitious slurry, configured to calculate the volume of the cementitious slurry in the mixer in order to produce an improved mixing process and/or an improved cementitious product. The mixer comprises a sensor to measure a parameter of the slurry in the mixer that is used to calculate the volume of slurry in the mixer.