A method of regenerating and reactivating inactive cement is disclosed. The method is performed in a disintegrator which includes a pin mill having beating pins arranged on two parallel counterrotating grinding disks in concentric alternating rings of increasing diameter. Inactive cement particles of a grain size of 7 to 10 mm are subjected to 3 to 8 mechanical beats within a time period of 0.01 to 0.001 seconds in the disintegrator and broken into separate particles of the original fineness or finer. In this manner, the separate particles are released from hydrated surface layers the cement particles thereby liberating non-hydrated layers.