The present invention relates to relates to methods of making concrete from cement and, in particular, methods of making usable standard concrete from aged or otherwise substandard cement.

A cement premixer includes a treatment container having a treatment space. The treatment container has a side wall and a bottom, and at least one stirring unit at least partially projecting into the treatment space. The stirring unit is connected to a shaft having an axis of rotation. At least one ultrasonic probe projects at least partially into the treatment space. At least one ultrasonic oscillator applies ultrasound to the at least one ultrasonic probe. The cement premixer has at least one first introduction opening for the supply of cement and an outlet for the flow supply line for feeding a cement suspension provided by the cement premixer into a concrete-mixing device.

The present invention relates to relates to methods of making concrete from cement and, in particular, methods of making usable standard concrete from aged or otherwise substandard cement.

A concrete compaction system includes an unbalance exciter for concrete compaction, a compaction detection device for detecting progress of the compaction in the concrete, and a vibration device for generating a haptic feedback when a prescribed progress of the compaction has been detected by the compaction detection device. An electric motor may drive the unbalance exciter and may be powered by an electric power supply and a converter device for converting an electric current from the electric power supply to a drive current for the electric motor. The compaction detection device may comprise a measurement device for measuring the current drawn from the electric motor. The compaction detection device may also comprise an evaluation device for evaluating the current drawn measured by the measurement device, for determining therefrom the progress of the compaction in the concrete, and for detecting whether a prescribed progress of the compaction has been achieved.

A compaction system has a compaction device with an electric motor for generating a compaction movement, an energy device for providing electric energy for the electric motor, a measurement device for measuring the current drawn by the electric motor, and an evaluation device for evaluating the current draw as measured by the measurement device and for determining, from this determination, the compaction progress in the medium being compacted. The evaluation device is arranged at least partly in an external device, spatially separate from the energy device and/or from the compaction device.