The crushed materials are cleaned for the first time in the washing drum and separated from unwanted components such as wood. They then enter the screening plant, where the various aggregates are extracted and another wash takes place using water. Coarse material is sieved several times, while fine material is separated off after the first sieve. The latter is then directed to the sand screw, where it goes through a last cleaning cycle. Ultimately, the granulation, as well as the mixture, have to be right. The deviation needs to be minimal to ensure that the concrete has the required properties.